i \ K^^■^ ■■^V'•'//'V' " v^ ■/*:>-^:^:- pi9 -'r^>-:^.T' «gr (Thr D. H- litll IGibrani North (Taroliita S-tate Imopratta Textiles TP913 C2 1905 THIS BOOK IS DUE ON THE DATE INDICATED BELOW AND IS SUB- JECT TO AN OVEJRDUE FINE AS POSTED AT the" CIRCULATION DESK. Digitized by the Internet Arciiive in 2010 witii funding from NCSU Libraries littp://www.arcliive.org/details/syntlieticdyestufOOcain THE SYNTHETIC DYESTUFFS THE INTEEMEDIATE PRODUCTS FEOM WHICH THEY ARE DERIVED. C. GRIFFIN & CO.'S TECHNOLOGICAL PUBLI CATIONS. SECOSD KIiiriDS. l.arif br„. Ilandmnnf Cloth. In Prepnratim. A MANUAL OF DYEING: For the Use of Practical Dyers, Manufacturers. Students, and all Interested in the Art of Dyeing. HV E. KNECHT, I'll. I), K.I.e., Cllll It.WVSOX, Y.lX.. K.CS., .iiul KK'llAKU LOEWEXTH.*.!., Ph.D. "The MOST KXIIAUSTIVE Hiid COMi'LKTK woKK oil the subject extaiit.'—r«/i7< Reeorder. Cotnjianinii Viiliime lit tht ahnre. In Larnr Sro. Ilaml/nmr Cloth. 16s. »><•'. A DICTIONARY OF DYES, MORDANTS, AND OTHER COMPOUNDS Used In Dyeing and Calico Printing. BY CHRISTOPHER RAW.SOX. F.I.C, F.C.S.. WAI.XKR M. l^AHHNER, KC.S., and \V. K. I,AYri>l.'K, I'h.l)., K.C'.S. "Turn to the book as one may on any subject, or any substance in connection witli the trade, and i reference is sure to be found. The authors have apparently left nothing out." — Ttxtite Mercuri/. In Lanif Srn. Uandtowe Cloth. With unmerom lllnntratiom. 9s. »'•'. TEXTILE FIBRES OF COMMERCE. A Handbook of the Occurrence, Distribution, Preparation, and Industrial Uses of the Animal, Vegetable, and Mineral Products used in Spinning and Weaving. liY WILLIAM I. UANSAN, Lecturer on Botany at the Ashtou Municipal Technical .School, cU-. '•UsEFDL i.NFORMATION ADMIRABLK ILLUSTRATIONS The information is not easily attain- able, and in its present convenient form will be valuable." — Textile Recorder. In .M,;liuin s™. Ilaniisonir- Cli'th. inili li;i Itluslrafionx. 16s. net. THE SPINNING AND TWISTING OF LONG VEGETABLE FIBRES (Flax, Hemp, Jute, Tow, and Ramie.) BV HERBERT R. CARTKR (BcUiisl, Ulient, and Lille). " We must highly commend the work as representing up-to-date practice."— JITatt/re. In Larrte ivo. With I llxistrationt and Pritited Patterns. 21s, TEXTILE PRINTING. A Practical Manual. Including the Processes Used in the Printing of Cotton, Woollen, Sillt, and Half-Silk Fabrics. BY C. F. .SEV.MOirR RDTIUVELL, F.CS. " By far the bkst and most fbactical book on tkxtii.k I'Kintixq which has yet been brought out.' Textile Mercuri/. Lome aro. Ilnnd.'iome Clot/,. |2s. 6d. BLEACHING AND CALICO PRINTING. A Short Manual for Students and Practical Men. BY GEORGE Dl'ERR, assisted by WILLIAM TrR.NIUl.L. ' When a ready way out of a ditttculty is wanted, it is in books likk this that it is found." -Textile In Lanie SCO. With numerous Illustrations. Tuo Voluuies. sold separately. TECHNICAL MYCOLOGY: The Utilisation of Micro-Organisms in the Arts and Manufactures. By Dk KRANZ LAKAIt. Translated by C. T. t". .SALTER. Vol. I.— ScnizoMYCKTic Fkkmf.ntation. 15s. Vol. II Part I.— Ei'MVCKTic Fermentation. 7s. 6d. Beautijtillii Illuslnited u-ilh Plates and IHa.tranis. 2ls. net. TRADES WASTE: Its Treatment and Utilisation. Br W. NAYLOR, F.C.s., A.M.Inst.C.E. ' There is proliably no person in England to-day better fitted to deal rationally wltli such a subject." — Briluh Sanitarian. WORKS BY GEORGE HURST, F.C.S., M. S.C.I. SIiCO.\I) KlilTlltX. llerised and F.idae.ied. Willi inniieri.us I II usi rations. 4s. 6d. GARMENT DYEING AND CLEANING. A Practical Book for Practical Men. " An important work, the more so that several of the lirancbcs of the craft here treated upon are almost entirely without Enj-iish manuals for the Kniilanee of workers.' -A"'r and Calieu Printer. PAINTERS' COLOURS, OILS AND VARNISHES. THE PAINTERS' LABORATORY GUIDE. By GEO, IIIRST, F.C.S Third EditioTj. Revised I By GKO. HURST, F.C.S. In Crown Svo. Ilandsome and Eidarged. Illustrated. 12s. 6d. I Cloth With Illustrntlons. 5s. London: CHAHLE.S GKIFFIN & CO., LTD., Exeteis Street, Strand. PREFACE. This book is not intended to be an exhaustive treatise on the subject, but is designed to serve the purposes of a laboratory text-book for the use of students in the chemical laboratories of technical schools, and of colleges where technical subjects, connected with this branch of higher organic chemistry, are taught. It is also hoped that matter will be found in it of use to chemists employed in works dealing with the synthetic dyestufFs. The need for such a book has been repeatedly pointed out to us by teachers who have control of laboratories where the usual course, only, of organic prepara- tion is carried out, and who have realised the incompleteness of such a course. It is hardly necessary to say that those students who wish to rise to a position of any importance as chemist in works where the organic dyestuffs are in any way used, must be thoroughly conversant with the ordinary facts of organic chemistry, and in this book we have assumed that such theoretical knowledge has been acquired. "With such grounding, we maintain that the average student can, without much trouble, master the main principles of the chemistry of the organic dye- stuffs, the one most important point for him to remember being that it is not necessary for him to attempt the impossible task of remembering the technical name and constitution of every existing dyestuff. Every dyestuff belongs to some group of organic compounds, the other members of which have analogous properties and analogous reactions; and if the student knows the reactions and characteristics of one member of the group, he will be able to infer, with certain reservations which he will learn by experience, the properties of the other members of the same group. In the first part of this book, therefore, we give a detailed theoretical descrip- tion of the intermediate products and the dyestuffs. In the second part we have described the preparation of one or more typical members of each of the groups of the intermediate products and dyestuffs. Methods of. preparation are described and quantities are recommended which will enable the ordinary apparatus of the laboratory to be available, but the materials employed are only such as would be used by a chemist actually experi- menting in a chemical works. Thus the use of ether is avoided except where absolutely necessary. By tliis means we hope to enable the student to pass from tlie college laboratory to the lalioratory of the works without that serious loss of time which he now often experiences before he can adapt himself to the totally different nature of his surroundings. Preceding the portion of tiie book dealing with the preparation of the dyestuffs will be found a short description of experimental d3'eing, in which will be found methods for producing quantitative dyeings on the fibre, in the laboratory. The complex nature of many of the commercial dyestuffs renders any chemical analysis of them extremely uncertain, and for the most part manu- facturers and others rely upon the comparative dye-trial for an appreciation of any jsroduct with which they may have to deal. A knowledge therefore of the methods by which the various dyestuti's can be quantitatively fixed upon the fibres is essential to those who intend ultimately to work with them. We have also described the various methods by which the value of any dye- stutf may be determined in respect to its behaviour on the fibre, towards reagents, and towards conditions which it is liable subsequently to meet with, and these data should not only be found of use to chemists investigating the nature of any new commercial product, but also to the research chemist, who, by this means, will be enabled to estimate the value of any new product which he may have isolated. In the preparations dealing with the raw materials and dyestuffs, the plan has been adopted of arranging so that each preparation is, as far as possible, a reduced facsimile of the corresponding preparation in the chemical works. Certain of the intermediate products will have to be subsequently used in the preparation of the dyestuffs, and in cases where such raw materials are not in ordinary use and readily obtained, we have given instructions for preparing them on a sufficiently large scale, to enable the student to obtain enough of them for future use. In the third part we deal with tiie identification and analysis of intermediate products and dyestuffs. In this case, also, we have described the actual processes in use in the chemical works. Many of these must necessarily be somewhat empirical, and we have only described those which, from our own experience, yield the most satisfactory results. Some of them — as, for example, Knecht's process for the titration of azo-dye- stuffs — have not, to our knowledge, yet been applied technically, but we have inserted them because we are of the o])inion that they are certain to be used in this connection in the future. The student will find by experience that the onlj' means of obtaining a knowledge of the reactions of the dyestuffs, both in the solid form and upon the fibre, is to possess a thorough knowledge of their constitution, ami tiiat if PREFACE. VU such knowledge is lacking no tables of reactions of whatever nature will be of any use. Such knowledge can only be obtained by studying the tlieory of the subject, and investigating for himself the properties and reactions of one or two members of each group. The need of chemists in works, connected with the dyeing industry, possess- ing means of ascertaining the purity and character of the products with which they have to deal, cannot surely be over-rated, and we hope that this book will enable students to gain an insight into, and a practical knowledge of, the pro- cesses adopted in commerce, which are not usually gained during a course of ■organic preparations under existing conditions. Many of the tables and matters dealing with the application of the dyestufts have been adapted from the excellent handbooks issued by the various German dye-works, especially those of the Farbwerke vorm Meister Lucius &■ Briining, Hijchst a/M., Messrs Leopold Cassella &, Co., Frankfort a/M., and of the Actien Gesellschaft fiir Anilinfabrikation, Berlin. We are also indebted to i\Iiss L. Drey, of the Manchester University, for the •careful manner in which she has repeated many of the preparations. J. C. CAIN. J. F. THORPE. Manchester, Ma)/ 1905. THIS WORK CONSISTS OF THREE PARTS: I'AUT [.—Theoretical. — A Theoketical De^^chiptiox ok the Intehmediaib Products and Dyestuffs. I'AIIT II. PraHical. — Methods for riiErAHixc the More Important Inter- mediate Products and Dyestuffs ox the Laboratory Scale. PART III. — Analytit-al. — The Analysis and 1dentific.\tiox of Intermediate Products and Dyestuffs, together with Methods for Detecting Dyestuffs ox the Fibre. .\PPEX!)I.\. — Containing Tables of Spkcific (Juavities of Solution.^, etc. CONTENTS. PAET L— THEORETICAL. g \.— INTERMEDIATE PRU DUCTS. PAO! CHAPTER I.— COAL-TAR : ITS OCCURRENCE AND PURIFICA- TION, 1- CHAPTER II.— NITRATION. Benzene series : General methods ; Orientation of the nitro-compounds — Naphthalene series : General Methods ; Orientation in the Naphthalene series, . . 5-i CHAPTER III.-SULPHONATION. Benzene series : General methods ; Benzene sulphonic acids, etc. —Naphthalene series : General methods ; Naphthylamine sulphonic acids — Naphthol sulphonic acids — Amidonaphthol sulphonic acids, ...... 9-1 f CHAPTER IV.— AMIDO-COMPOUNDS. Benzene series : Motiamines \ General methods — Diamines ; General methods and description — Reactions of the amido-group^Naphthalene series : General methods and description — Preparation of diazo-salts — Constituiion of diazo-salts, 19-2( CHAPTER v.— HYDROXYL COMPOUNDS. Benzene series : General methods — Reactions of the hydroxyl group — Naphthalene series : General methods and description, ..... 27-25 CHAPTER VI.— CARBOXYL COMPOUNDS AND ALDEHYDES. Other imjiortant conijiounds used as intermediate products — Carboxyl compounds — Ketones — Aldehydes — Aliphatic derivatives, ..... 29-32 § 2.— THE DYESTUFFS CHAPTER VII.— APPLICATION OF THE DYESTUFFS. Their classification — Theories of dyeing — Acid dyestuifs— Basic or tannin dyestuH's — Direct or substantive cotton dyes — Ingrain colours— llordant dyestuifs — Vat dyes — Developed dyes, ........ 33-37 CHAPTER VIII.— CLASSIFICATION OF THE DYESTUFFS. Chromophore, chromogen, and auxoiliruiuc — C'liiumi)|iliures ixM'uniiig in tin- cliivf dyestulf groups — Relation betwueti constitution and lake-forming properties, . CHAPTER IX.— THE NITROSO-DYESTUFFS. (Quinoneozimes.) Constitution, properties, and general methods of formation, ... 42-43 CHAPTER X.— THE NITRO-DYESTUFFS, Their constitution, properties, and principal methods of preparation — The Stilbene or Azoxy-dyestutfs, ......... 44-40 CHAPTER XL— THE AZO-DYESTUFFS. General methods of formation— Laws regulating their formation — Abnormalities — Constitution — The influence of groups upon their colour — Substantive cotton dyes— Historical — Division of the azo-dyestutl's- .iVoHasu : (1) Amidoazo-com- pounds; (2) O.xyazo-dyestufl's— Z)isn:o : (1) Primary disazo-dyestutfs ; (2) Secondary disazo-dyestufl's— DyestulTs from tetrazo-salts — Trisazo-dycstujfs— Tetrahisazo-dyestujfs, ........ 47-75 CHAPTER XII— HYDRAZONE DYESTUFFS. Tartrazine — Its mode of production and constitution, ..... 76 CHAPTER XIII.— AURAMINE. Preparation and constitution, ........ 77-78 CHAPTER XIV.— TRIPHENYLMETHANE DYESTUFFS. 7'lic Malachite green series (Diamidotriphenylmethane) : Suli>honic acids of the Malachite green series — Patent blues— The Eosaniline Series (Triamidotri- phenylmethane) : Introductory ; Laws regulating the formation of Triphenyl- methane dyestutls ; Formation of the dyestuli' from the dye-base ; Constitution of the Ro.saniline dyestulls ; General methods of formation ; General descrip- tion of the Kosaniline dyestuft's ; Phenyl and tolyl derivatives of Rosauiline ; Sulphonicacids of the Rosaniline dyestulls — Hosolic acid series (Trioxytrii>henyl- methane) : Aurine, etc. ; The influence of groups and constitution upon the colour of dyestulls of the Triphenylmethaue .series, .... 79-96 CHAPTER XV.— PYRONINE DYESTUFFS. (1) Diphenylviethcine derirotifcs: The Pyroniues ; General methods of formation and constitution — (2) Triphaiyl methane derivatives : The Phthaleins— Rhodamines and Eosiues— Galleine and Ca>ruleine -The constitution of the Pyronines, . 97-111 CONTENTS. XI PAGE CHAPTER XYL— ACRIDINE DYESTUFFS. General methods of formation, and description of the more important members, . 112-113 CHAPTER XVII.-OXYKETONE DYESTUFFS. (1) Munokctoiies : Preparation and description — {2) Diketones : Alizarine; Historical; Constitution ; llode of formation ; Polygenetic and Monogenetic dyestuffs ; Derivatives of Alizarine ; Alizarine blue ; Isomerides of Alizarine ; Trioxy- anthraquinones ; Tetraoxyanthraquinones ; Peutaoxyanthraquinones ; Hexaoxy- anthraquinones ; Indanthrene, ....... 114-123 CHAPTER XVIII.— DIPHENYLAMINE DYESTUFFS. Introductory. — Indophenols — Thiazines— Oxazines— Indaraines — Azincs : (a) Eurho- dines ; (6) Aposafranines ; (c) Safranines ; Constitution and history ; Forma- tion ; (d) Indulines and Nigrosines ; The mode of formation of Induliue dye- stuffs from amidoazo-compouuds ; Nigrosines from Nitrobenzene ; Aniline black, .......... 124-150 CHAPTER XIX.— QUINOXALINE DYESTUFFS. Their preparation and constitutiou, . . . . . . . 151 CHAPTER XX.— THIAZOL DYESTUFFS. Primuline : its preparation, constitution, and projierties — Other dyestuffs of the series, 152-153 CHAPTER XXI.-QUINOLINE DYESTUFFS. Quinoline yellow : its formation and constitution, ..... 154 CHAPTER XXIL— INDIGO. Introductory — History of Baeyer's synthesis — Other syntheses and their commercial application — Indigo blue, ....... 155-165 CHAPTER XXIII —THE SULPHUR OR SULPHIDE COLOURS. Their history and methods of preparation, ...... 166-167 CHAPTER XXIV.— XANTHONE DYESTUFFS. Indian yellow — flavones and Flavonoles ; description, constitution, and synthetic CHAPTER XXV.-A SHORT HISTORY OF THE SYNTHETIC COLOURING MATTERS, i74-i76 Xll CONTENTS. PAOI TAKT 11— riLVCTICAL. CHAPTER XXVI.— THE TECHNICAL LABORATORY. Debcription of apjiai-atus — Library — General operations — Heating — Heating under pressure — Work with fuming sulphuric acid — Distillation — Distillation under diminished jiressure — Distillation with steam — Filtration — Salting out — Indicators and Reagents — Tables of important molecular weights — Principal processes in the technical laboratory for the preparation of raw materials, . 177-191 CHAPTER XXVIL— PREPARATION OF INTERMEDIATE PRODUCTS. Benzene series : (1) Nitrobenzene — (2) Aniline— (3) Acetanilide — (4) ju-Nitracetanilide — (5) jj-Nitraniline — (6) ^-Araidoacetauilide — (7) p-SuIphanilic acid — (8) Dimethylaniline — (9) Nitrosodimethylaniline hydrochloride— (10) Dietliyl-Hi- amidophenol — (11) TO-Dinitrotoluene — (12) m-Toluylenediamine — (13) Benzidine— (14) Thiocarbanilide — (15) Benzal chloride — (16) Benzaldehyde — (17) a-Dinitrophenol, ........ 199-21! CHAPTER XXVIII.— PREPARATION OF INTERMEDIATE PRODUCTS. Napldhalcnc series: (IS) Naphthalene /3-sulphonic acid — (19) 3-Naphthol — (20) j8-Naphthol-6-sulphouic acid (Schaffer's salt)— (21) 6-Naphthol-3 : 6-disul- phonic acid (R salt)— (22) a-Nitronajihthalene- (23) o-Na]>hth}ianiine — (24) Naphthionic acid — (25) a-Naphthol sulphonic acid (1:4) (Neville & M'inther's acid) — (26) o-Naphthylamiue trisu][)honic acid— (27) Amidonaphthol disul- jihonic acid H — (28) /3-Naphthylamine — (29) 3-Naphthylamine disulphonic acid G — (30) Amidona]ihthol sulphonic acid 7 — Anthracene series: (31) Anthraquinone— (32) Anthrai|uiaont' sulphonic arid. .... 213-22i CHAPTER XXIX.— PREPARATION OF DYESTUFFS, ETC. (1) Fast green (Dinitrosoresorcin)— (2) Naphthol yellow S— (3) Chrysoidine R — (4) Orange II. — (5) Fast red B— (6) Fast red A— (7) Chrysamine G— (8) Benzopurpurine 4B— (9) Diamine fast red — (10) Benzo -sky blue— (11) Diamine black RO— (12) Naphthol blue black— (13) Naphthol black B— (14) Isodiphenyl black — (l.'i) Auramine — (16) Malachite green — (17) Magenta —(18) Methyl violet B— (19) Aniline blue (si)irit soluble)— (20) Alkali blue— (21) Soluble blue— (22) Fluorescein— (23) Eosine— (24) Rhodamine B— (25) Benzoflavine — (26) Alizarine yellow A — (27) Alizarine— (28) Indophenol — (29) Meldola'sblue— (30) Gallocyanine— (31) Methylene blue— (32) Safranine — (33) Induline (spirit soluble) — (34) Induline(water soluble)— (35) Primuline — (.■56) Indigo (Sandmeyer's synthesis)— (37) Sulphur black T, . . 225-26! I-AIIT III.— ANALYTICAL. CHATTER XXX. INTERMEDIATE PRODUCTS. Inorganic products : Methods of analysis of inorganic substances — Fuming sulphuric acid — Zinc dust — Lead jieroxide — Sodium sulphide — Sodium nitrite — AUphatic compounds : Formaldehyde; Methyl alcohol — Aromatic compounds : Benzene ; Toluene ; Nitrobenzene ; Aniline ; Diniethylaniline ; Diethylaniline ; Naphthylamine ; Nitranilines ; Suliilianilic acid ; Xylidine ; o-Toluidine ; Hi-Phenylenedianiine ; Benzidine ; Tolidine and Dianisidine ; Phenol ; Re- soreinol ; Benzaldehyde ; Benzoic acid ; Salicylic acid ; Phthalic anhydride ; Naphthols; Naphthol sulphonic acids; Naphthylamine sulphonic acids: Anthracene ; Turkey-red oil, ....••• CHAPTEK XXXI. -THE APPLICATION OF THE COLOURING MATTERS. (1) The behaviour of the {irincipal fibres towards reagents— (2) Experimental dyeing ; General remarks ; Standard solutions ; The dye-bath— IFool dyeing : Purification; Acid dyestuffs ; Basic dyestulls ; Mordant dyestuffs — Silk dyeing: Preparation of silk ; Acid dyestuH's ; Basic dyestuffs— CoHo» dyeing: Substantive cotton dyes ; Diazotising and developing— Dyes developed directly on the cotton fibre — Hasic dyestuH's on tannin and tartar emetic mordant; Acid dyestuffs ; The sulphur colours on cotton ; The vat colours on cotton and wool ; The mordant dyestuH's on cotton ; Turkey-red ; The modes of producing the various mordants on cotton ; Alumina mordants ; Iron mordants ; Chrome mordants and tin mordants ; Colours produced on the fibre by oxidation ; Aniline black, ......... 283-295 CHAPTEE XXXII.— THE VALUATION OF A COLOURING MATTER. Determination of solubility in water — Enualising power— Its behaviour on tlie fibre towards reagents — Fastness to light — Fastness to washing and milling — Fastness to alkalies — Fastness to acids — Fastness to carbonising — Fastness to stoving — Fastness to bleaching, ....... 296-29 CHAPTEE XXXIII— THE QUANTITATIVE AND QUALITATIVE ANALYSIS OF DYESTUFFS. Quantitative : Azo-dyestuffs — 'Witt's reduction method — The action of concentrated sulphuric acid on the azo-dyestufi's — Titration with titanous chloride — Methylene blue — Indigo — 'Various methods of estimation — Titrations with Night blue — Qualitative : Estimation of the dyestuffs in powder form ; Detection of impurities ; Estimation of the nature of a dyestuff ; Tables giving the reactions of typical dyestuffs in powder form, ...... 300- CHAPTEE XXXIV.— INVESTIGATION OF DYESTUFFS ON THE FIBRE. Reactions of the more important dyestuH's on the fibre— Separation of mixture of dye- stuffs on the fibre by means of amyl alcohol — Titanous chloride as a reagent for testing dyestuffs on the fibre — Spectroscopic investigation of the dyestuffs — Tables giving the reactions of typical dyestuffs on the fibre, . . . 350-378 XIV CONTENTS. l-AOB APPENDIX. International atomic weiglits— Tables : S|iicilic gravity of solutions of acetic acid, Hydrochloric acid, Nitric acid ; Caustic soda ; Sulphuric acid ; Ammonia ; Tannic acid ; Sodium carbonate ; Common salt ; Sodium sulphate ; Sodium bisulphite ; Sodium acetate ; Chloride of lime ; Aluminium sulphate ; Alu- minium acetate ; Tartar emetic ; Copper sulphate ; Iron acetate (pyrolignite of iron) ; Chromium acetate ; Ferrous sulphate — Comparative hydrometer scale, specilic gravity, Twaddell and Bauine, ..... 379-390 ERRATA AND ADDENDA, ....... 391 INDEX, ... 392 ABBREVIATIONS. E.P., . A.P., . D.P., . F.P., . Ann., . A. Ch., Bcr., . Brit. A. Rcj.^ Chem. Zcit., Diagl. pol. ./, . J.C.S., J.S.C.I., . J. Soc. Dyers, Zeit. Farb. Ch English Patent American Patent. Oei'man Patent. French Patent. Anna/en I I + ^ ! , ^ H, CH CH CH CH CH CH n CH \x \.- -■ C^' CH CH CH CH CH 3 mols. benzene. 2 mols. naphthalene, acetylene. acetylene. (Berthelot, A. Ch., [4], ix. 469.) Anthracene can also be formed from naphthalene and acetylene : — ,H CH CH -.C/xC^ , ^CH ■c-c^^^ - CH CH CH anthracene. The purification of coal-tar is effected by distillation. The crude tar, which contains a considerable quantity of ammonia water, is first freed from this bj' gravitation. It is then transferred to the stills, which are vertical, and con- nected with a worm surrounded with water, which can be either cooled or warmed as occasion requires. The tar in the stills is kept in motion by means of mechanical stirring apparatus, or by passing in a current of superheated steam. The first operation consists in separating the distillate into four fractions: — I. The liijld oil, which consists of that portion which passes over up to 150° C, and contains benzene, toluene, etc. (this fraction floats on water, hence its name). CH CH CH^^/^CH CH\ A /CH CH CH CH CH CH CH naphthalene. 2 mols. acetylene. COAL-TAR : ITS OCCURRENCK AND PURIFICATION. 3 II. The middle oil, B.P. 150-200° C, consistiui,' of phenol, naphthalene, etc. (has sp. gr. of about 1). III. The heavi/ oil, B.P. 'iOO-'SlO" C, consisting of najihthalene, phenols, quinoline bases, etc. (sinks in water). IV. The anthracene oil, B.P. 300-400° C, which contains anthracene, etc. This fraction, from its colour, is also termed "green oil." The residue in the retort is run out and is known as " pitch." These four fractions are now subjected to further purification. Each fraction is first washed with dilute acids, and then with alkalies — in the first case to remove the bases, in the second to remove the phenols, etc' It is finally washed with strong sulphuric acid and then again subjected to careful frac- tional distillation, one or other of the various fractionating columns being employed in order to effect complete separation. In this way benzene and toluene are obtained pure. The three xylenes, which owing to the similarity in the boiling-points cannot be separated by fractional distillation, are not separated, but are used as commercial .xylene. According to Brunck, the total output of benzene and toluene for the year 1900 amounted to 2.5,000 to 30,000 tons, of which about four-fifths must be taken as representing benzene. This quantity of benzene and toluene is not all derived from coal-tar, since, of late years, a considerable quantity of these substances has been recovered by using the closed coke ovens instead of the open ones formerly employed. It has been stated that the German coke factories produced upwards of 7000 tons of benzene in this way during the year 1900. Naphthalene is deposited from the fractions which pass over between 180° and 250°, and is purified by first pressing, then washing with alkali and acid (if necessary), again pressing, and finally subliming or distilling. In spite of the enormous quantity of this substance used for the preparation of the various and important sulphonic acids of the naphthols and naphthylamines, the supply of naphthalene produced in this way from coal-tar was always greater than the demand, and consequently a considerable quantity was yearly burnt to lamp-black. The discovery by the Badische Anilin and Soda Manufactory, that naphthalene could be easily converted into phthalic anhydride by distilling with fuming sulphuric acid in the presence of mercury, and the elaboration of their commercial process for the manufacture of artificial indigo, using phthalic anhydride and lience naphthalene as a starting-point, has caused this substance to become one of the most valuable products of the distillation of coal-tar. Anthracene is deposited from the anthracene oils as a green slimy mass, which is partially purified by pressing ; in this state it contains about 12 to 14 per cent, of anthracene. There are a number of processes by which the crude anthracene may be purified sufficiently for conversion into anthraquinone, in which state it finds its most important application, namely, in the preparation of artificial Alizarine. I. The crude anthracene is extracted with creosote oil (heavy oil), which dis- solves out the impurities and leaves a product containing about 40 per cent, of anthracene. This is usually not further purified, but is directly oxidised to anthraquinone, a process which causes the various impurities to be eliminated. The crude anthracene contains other hydrocarboui?, such as phenanthrene, fluorene, pyrene, etc., which on treatment with bichromate of potash and sulphuric acid remain for the most part unaltered, whilst the anthracene is ' Latterly it has become more general to begin with alkaline washing, follow with sulphuric acid, and finish with a weak solution of caustic soda. 4 SYXTHKTIC DYKSXrFFS. oxidised completely to antliraquinoue ; on treating the oxidised mixture with moderately strong sulphuric acid the anthraquiuone remains unaltered, but the hydrocarbons are converted into sulphouic acids. On pouring the solution into water the sulphonic acids dissolve and the anthracjuiuone is deposited. This is finally purified by sublimation with super- heated steam. II. Another method consists in heating the crude anthracene with sulphurous acid, whereby the bulk of the impurities pass into solution and a product is left containing about 85 to 90 per cent, of anthracene. III. Other solvents which have been found advantageous for this purpose are acetone oils and pyridine ; by this last solvent a product containing from 95 to 98 per cent, of anthracene can be obtained. Phenol is recovered from the alkaline washings of the various distillates on acidifying, for which purpose carbonic acid, in place of a mineral acid, has lately found a wide application. The chief quantity of phenol is obtained from the " creosote oils," which form the intermediate, running between the light and the middle oils. It is purified by distillation. Altogether more than one hundred substances have been isolated from coal-tar. The average percentages of the more important are : — Average yield ]>er cent, of the weight of tar. Benzene, .... O-G-OS Toluene, Xylenes, Phenols, . Cresols, Naphthalene, Anthracene, 0-2-0-4 0-2-0-3 0-2-0-3 0-5-0-8 2-10 0-2-0-4 1. 2. 3-0 2-0 per cent. 1-5 0-8 „ 35-0 250 „ 500 co-0 „ 10-5 12 2 „ The following table shows the average percentage of the products obtained from 100 tons of coal-tar (Roscoe): — Naphtha, .... Light oils and carbolic acid. Heavy oils, naphthalene, anthracene, Pitch, ..... Water and loss, . . . • 1000 1000 „ Colson (Neicbigf/in>i, p. 407) obtained from one ton of tar : — Crude naphtha, 30 per cent, at 120° C, . 6-79 gallons. Carbolic acid, crude, 60° C, . . . 350 „ Heavy naphtha, 20 per cent, at 160° C, . . 3-55 „ Creosote, ...... 5804 Ammoniacal liquor, 10 oz., . . . • 500 „ Naphthalene, ..... 33-91 lbs. .\nthracene, 33 per cent., .... 13-60 „ I'itch, ...... 12-67 cwts. The most favourable temperature for the production of aromatic hydri' carbons is 700-800° C. (jtrivate communication from W. A. Bone). CHAPTEK II. NITRATION. (Berizme Series.) Speaking generally, the nitro-groiip (NO^) is introduced into the aromatic nucleus by the direct action of nitric acid. This action, which is characteristic of aromatic compounds, may be repre- sented by the equation CeH,. + NO.,OH -> C6H-,N0., + H.,0, the further action of nitric acid producing bodies containing two or more nitro- groups, according to the equation CbHsNO. + NO.jOH -5. CsH,(NO.j),. + HoO. Not only do the aromatic hydrocarbons yield nitro-derivatives, but also the many derivatives of these hydrocarbons made by substituting the hydrogen atoms by the hydroxyl (OH), amino (NHj), aldehyde (CHO), carboxyl (COOH), etc., groups, the formation of the nitro-compound talcing place with greater or less ease according to the nature of the substance nitrated. Thus, in cases where the compound is very easily nitrated, the action of nitric acid diluted with water is sufficient to bring about the formation of the nitro-compound, whilst in other cases the presence of sulphuric acid is necessary before nitration can be effected. In nitrating with nitric acid in the presence of sulphuric acid it is usually advisable to add the substance to be nitrated gradually to a well-cooled solution of nitric and sulphuric acids (e.ij. naphthalene), although in special cases the reaction may be varied with advantage by dissolving the substance in con- centrated sulphuric acid, and gradually adding the nitric acid to this solution (e.g. nitro sulphonic acids), or also by adding the mi.xture of acids to the pure substance {e.g. benzene, etc.). In many cases nitration can be carried out by adding powdered sodium nitrate to the solution of the substance to be nitrated in sulphuric acid. On the large scale the operation is effected in an iron pan fitted with a stirrer. The pan is so arranged that it can be cooled by a stream of cold water on the outside, as nitrations are usually carried on between 0° and 40°. If the nitric acid or mixture of this with sulphuric acid is to be added to the substance contained in the pan, it is measured in a stoneware vessel placed at a convenient height above the pan. The product of nitration is worked up either by allowing it to settle and decanting, or (if a liquid) by pouring upon ice. If the substance nitrated is a sulphonic acid, the product is usually diluted with water and isolated by means of its calcium salt. Reactions of the nitro-groiip. — The nitro-compounds of the hydrocarbons are indifferent neutral substances like the hydrocarbons themselves, but the entrance of the nitro-group into tiie aromatic nucleus, already containing either an acid or a basic group, modifies the reactions of these groups. 6 SYNTHETIC DYESTUFFS. Thus phenol (C,H.OH), which is a sufficiently strong acid to form a stable sodium salt with caustic soda, but not acid enough to decompose carbonates, becomes, on conversion into trinitropheuol (picric acid), C,.H.,(N0.,)30H, a strong acid which readily reacts with carbonates. The same change is produced in the conversion of a-naphtliol into Naphthol yellow (see page 45). Conversely, aniline, Ci^HjNH.,, is converted on nitration into nitro-aniline, CgH^(NO.,)NH„, a substance which is very much less basic than aniline itself. The chief reaction of the nitro-group. and the one which causes it to be of so much importance in the preparation of the dyestuffs and the intermediate products of the dyestuft' manufacture, is its beliaviour on reduction. When treated with nascent hydrogen, ^ it is converted into the amino-group according to the scheme R. N0., + 3H., -> R. NHl, r2H„0. (See p. 19.) Orii>nfation of the nitro-cumpoundx.—Ow'nv^ to the symmetrical nature of the benzene ring only one nitrobenzene is formed by the nitration of benzene. When an alkyl group is present the nitro-group enters in the ortho- and para-, but not the Wf^a-position. Thus — R. R. R. A ^ l^lNO. and 1^1 \y \y \y NO., The same position is taken up when the benzene ring contains an hydroxyl group. Thus (iriho- and ^ja/'a-nitrophenol are formed bv the nitration of phenol, C,H,(OH). When eitiier the aldehyde (CHO), carboxyl (COOH), or cyanogen (CN) group is present in the benzene ring, the ?«e/(i-nitro-compound is produced on nitration. Thus benzaldehyde (C,;H-CHO), benzoic acid (C.-.H^COOH), and benzonitrile (C^^HjCN) yield on nitration CHO COOH CN X\ /'\ /-x V^V '\/^o., I^'uo, ?n-iiitrobenzaldehyde, ?/i-nitrobenzoic acid, //(-nitrobenzonitrile, respectively. The )i(e/((-position is also taken up when a benzene derivative already contain- ing a nitro-group is further nitrated. Thus nitrobenzene on further nitration yields ?rte/a-dinitri)benzene N0„ NOj /\ , \ "^ N NO., and o)-//jo-nitrotoluene and ci;, so that the use of an excess of sulphuric acid is adopted in the example on p. L'17. NH._, I I I + a.o The fact that the sulphonic acids are mostly soluble in water renders it necessary that some method should be adopted In- which they can be separated from the excess of sulphuric acid used in the sulphonation. Here, again, the special experimental methods have to be used in special cases. Those usually found most effective being — (1) Precipitating the sulphonic acid from its solution by means of a saturated solution of some salt, such as sodium chloride, potassium cidoride, etc. (2) Treating the mixture of sulphuric acid and the sulphonic acid with either calcium, barium, or lead carbonates and filtering. Since in many instances sulphonic acids form soluble salts with these metals, they pass through in solution whilst the sulphates remain on the filter. The calcium salt is usuallj' made on the large scale. (3) In some cases the sulphonic acid is insoluble in cold sulphuric acid, and it is only necessary to filter the solution through asbestos or glass-wool in order to obtain it pure. The orientation of the sulphonic acids is the same as that indicated in the case of the nitro-compounds. Thus benzene sulphonic acid on further sul- phonation, is converted into mefn-hcn/.ene disul]>houic acid l^lsOjH lieactioHf. — The most iuiportant reaction of the sulphonic acid group is its conversion into the hydroxyl grou|> (OH) on fusion with caustic soda. Thus benzene sulphonic acid under these conditions is converted into " phenol, CsHsSOjH + NaOH -» CcHjOH + NaHSOj. (See p. -27.) Anotiier important reaction, and one that is sometimes used in preparing compounds relating to tiie dyestuffs, is the production of the nitriles by fusing the sulphonic acid with potassium cyanide, thus : — R. SO3H-1-KCN -> K. CN I KHSO3. Tiie introduction of the sulphonic acid group is also of considerable import- ance ill the case of finished dyestuffs themselves, since, by its means, a dycstuflf insoluble in water may be made soluble, and a .soluble dyestuff more soluble. This, however, will be dealt with under its own head. SULPHONATION. {Xaphthalene Series.) tl ; 1 ligh temperatures. aULrnuWAllUW. (.Mijmuiaiene aenes.) According to the law discovered by Armstrong and Wynne, the sulphonic acid group enters the a-position at low temperatures, but the ^-position at hieh temperatures. SDLPHONATION. I i Thus on treating naphthalene with strong sulphuric acid at 80° C, a-naphtha- lene sulphonic acid 00 is produced; whilst at 180° C, ^-naphthalene sulphonic acid is the chief product The same law holds on further sulphonation. Thus the second sulphonic acid group enters the most remote a-position at low temperatures, and the most remote ^-position at high temperatures. Thus the sulphonic acid SO^H SO,H I I I gives, on further sulphonation in the cold, I J J as chief product, and at higher temperatures the sulphonic acid SO3H sod.J\J whilst the /3-sulphonic acid gives, on further sulphonation at 160° C, the acids 2 : 6 and 2 : 7 as chief products. The following table shows the production of the technically important sulphonic acids of naphthalene {Heumann) : — 4 ^./„i 00, W sOO^ s \ I / s s 12 SYNTHETIC UYESTUKFS. The sulphonic acids of naphthalene are of considerable importance, since from them are produced the valuable naphthols on fusion with caustic soda. Of much greater importance, however, are the various sulphonic acids derived from the naphthylamines and iiuplithols, made either by treating them directly with sulphuric acid or by iudirect means. These substances find an extensive application in the preparation of the azo- dyestuffs, and the special methods of preparation and the properties of the more important of them must therefore now be given. Naphthylamine Sulphonic Acids. These are obtained In- the following general methods : — ( 1 ) By sulphouatiug an amido-eompound. (2) By sulphonatiug a nitro-compound and sul)sequent reduction. (3) By nitrating a sulphonic acid and subsequent reduction. The last two methods will be first considered, and as the general operations of nitration and sulphonation have been already discussefd, the different products formed are best explained by the following table (Hewnann) : — Chief product is represented by > Bye-product is represented by > S = SO3H. Nitronaphthalene mnnosulphonic acids. CO' 00 CO-c6WcO3 00^ > s NO2 NO; NO2 Nitronaphthalene disulphonic acids. S CO, sCO, WOOsCp^ CO ooo-co soa«o CO soo^ S S NO; S In carrying out the first method, both a- and ^-naphthylamine are used on the large scale. SULPHONATION. T3 Table showing the sulphonic acids derived from a-naphthylamine by sulphonation (Heumann) : — NH2 JnHj ,,-''''|n: /NH: s/V ^ S, s • NH2 JnH2 s s s s Sulphonic acids derived from /i-n:iphthylamiue by sulphonation {Heumann) :- ^CO s^^Y>"^ ^rry^^ ^(Yy-^ s s s The following is a short description of the more important naphtbylamine sulphonic acids ; for a more detailed and complete description a larger work must be consulted (see Green, Organic Colouriiig Matters, 1904 ; Tiiuber and Norman, Derivate des Naphtalins, 1896, etc.) : — Naphthionic acid NH., L ' J s6^ prepared on the large scale by roasting a-naphthylamine acid sulphate mixed with about 3 per cent, of its weight of oxalic acid, to 170-180°. The free acid is difficultly soluble in cold water, more easily in hot. The sodium salt " naphthionate " crystallises with four molecules of water. The diazo-compound is yellow and insoluble in water. 14 SYNTHKTir DYESTUFFS. By hcatinj; the sodium salt with four parts of tuiphtlialenc, a molecular rearrangement takes place and "ortho-napluhionic acid" is formed NH., NH, SO3H This acid is made on the large scale, but not to any great extent. By the cold nitration of naphthalene a-sulphonic acid and subsequent reduction of the product, two acids are obtained, viz. : — S acid (a-naphthylamine sulphonic acid 1 : 8, fcjchoellkopf), and L acid (a-naphthylainine sulphonic acid 1 : 5, Laurent). The 1 :8 acid is the more important and is the chief product. The free acid is nearly insoluble in cold water. When naphthalene /S-sulphonic acid is nitrated and reduced, the three so- called " Cleve's " acids are obtained, viz., a-naphthylamine sulphonic acids I : 6, 1 : 7, and 1 : 3. Tlie first two are formed in about equal proportions and form the bulk of the product, the last being present in traces only. The reduction mixture is u.sually directlj- combined with diazo-compounds in the production of black polyazo-dyes for cotton (direct). By salting out the reduction mixture, or acidifying, the 1 : 6 acid is pre- cipitated. This gives rather better shades than the 1 : 7. The more important of the monosulphonic acids of /3-uaphtliylaniine are the 2 : 6 and the '2 : 7 acids. The former (Bronner's acid) is obtained from "Schaffer's acid" (p. 16) by heating it with strong aqueous ammonia in an autoclave to 180°. The free acid is difficultly soluble in cold water; the sodium salt easily soluble. The 2 : 7 or " F " acid is similarly obtained from the corresponding yS-naphthol sulphonic acid (p. 16). The acid is more soluble in hot water than the preceding one, and the sodium salt is easily soluble in water. Of the polysulphonic acids of the two naphthylamines, the following are the technically important: — l-Naplithi/lamine-4 : 7 -dii-ulphonif arid (Dahl's No. III. acid). — When naphthionic acid is further sulplionated, a mixture of two disulphonic acids is obtained, viz., about 66 per cent, of the above Hcid and about 33 per cent, of the 1:4:6 acid (Dahl's No. II.). The latter is worthless for the preparation of azo-colouring matters; the former, however, is used in the ])reparation of wool blacks. The acid is easily soluble in hot water, sparingly soluble in cold. 2-Naj>hthyt(imhie - 3 : 6 - (Jisulphonir ari R. NH., + 2H.,0. Practically any acid-reducing agent may be used for this purpose, and it is usual on the laboratory scale to employ tin and hydrochloric acid ; but owing to its cheapness iron generally replaces the tin technically. Furthermore, the use of iron has another advantage, since, by its means, considerably less (about J^j) hydrochloric acid than that theoretically required can be used. This is explained in the following way : — The first action of the iron and hydrochloric acid is represented by the equation R. NOj + SFe + eHCl -> sreCl, + 2H.3O + R. NH.. The nitro-corapound now oxidises the ferrous chloride, and is at the same time reduced thus : — R. NO,, + 6FeCl., + 4H.p -^ R. NHj + 4FeCL + 2re(OH)3. The excess of iron at once reduces the ferric chloride to ferrous chloride, and the above reaction goes on again, a small initial quantity of ferrous chloride thus carrying on the reduction to the end. From the various nitro-derivatives of benzene the corresponding amido- bodies may be prepared by reduction, although special methods have to be adopted to suit special conditions. Another method of introducing the amido-group, and one frequently em- ployed, consists in reducing an azo-compound. A good instance of this, and one which serves to explain the process, is the following : — o-Toluidine is a bye-product in tlie manufacture of Magenta, and on treatment with nitrous acid in the presence of a small quantity of mineral acid is converted into amidoazotoluene \yCH, N CH^ which, on reduction, splits up iu the manner indicated by the line, giving a 20 SYNTHKTIC DYRSTrKFS. mixture of o-tohiidiue and ^)-tohiylenediamine a J, I^^ H.JI^>NH., Tlie mixture of these two bases is subsequently used in the preparation of Safninine (see p. 2G1). An iiltogether different method is one which is used in tlie preparation of /j-nitraniliue (Chiytou Aniline Co.; D.P. 148,749). This consists in heating ^)-chloronitrobenzeue with eicess of aqueous ammonia at 1.30-1 SO'. Diainines. The chief diamines of the benzene series which are used in the manufacture of dyestufts are ?n-phenylenediamine, ?».toluj'lenediamine, and j)-phenj'leuediaminc (in the form of its monoacctyl derivative). The meta-diamines are used chiefly as components in tlie preparation of azo-dj'es and Bismarck brown, while the para-derivative is used as a diazo- (or tetrazo) compound. Both //(-plienylene and //i-toluylenediamine are obtained by the reduction of the corresponding dinitro-coinpounds with iron and a little hydrochloric acid. Nitrous acid converts them into Bismarck brown, although by acting on ?M-phenylenediamine with nitrous acid, which is added to it suddeuly, nitroso-7n-[)henylenediamine is formed as well as Bismarck brown (Tiiuber and Walder, Ber., 1900, xxxiii. 2116). As ^-phenylenediamine itself cannot be satisfactorily diazotised, it is usually prepared in the form of its monoacetyl compound by reduction of /'-nitracet- anilide with iron boiings and acetic acid (see example, p. 20.'i). The amido- acetanilidc or acetyl-/;-phenylenediamine is casilj' and quantitatively diazotised, and may be coupled with any component. If now the product be heated with alkalies, the acetj'l group is split of!', and the second amido-group may now, in like manner, be converted into the diazo-group. Another way of producing the same end-product, althoigh not so conveniently carried out, is to start from /j-nitraniline and to diazotise it and couple with a component. Tlie product is now reduced carefully (so as to leave the azo-group -N = N- unattacked) with sodium sulphide, and the resulting amido-group diazotised as before. A most important class of diamines is that belonging to the diphenyl series, for a large niunber of these when tctrazotised and coupled with suitable com- ponents yield dyestuffs capable of dyeing immordanted cotton direct. This property is, indeed, not confined to the diphenyl derivatives, but is possessed by ;)-phenylene diamine itself, and by diamines of the diphcnylaminc series and others. The simplest member of tliis group is jt)-;'-diamidoiliphonyI or benzidine NH., u A I J NH AMIDO-COMPOUNDS. 2 1 This is prepared by the alkaline reduction (Zn and NaOH) of nitrobenzene by which hydrazobenzene, C,.H^NH - NH.C,.Hr,, is obtained, and then by dissolving this in hot hydrochloric acid a remarkable molecular change takes place, whereby benzidine is produced, CfiHjNH -NHCoHj -5. NH,.CsHj.C(,H4.NH2. The reduction to hydrazobenzene has also been brought about of late years electrolytically. (See Elbs' Electrolytic Preparations, 1903, p. 82; also D.P. 116,467 and 116,871.) By subjecting o-nitrotoluene to the same process (alkaline or electrolytic reduction), hydrazotoliiene is produced, which is, in like manner, by the action of acids, transformed into ^j-^j-diamidoditolyl or tolidine NO, CH., CH, •JCuHj " -5. C„H^( )C,.H4 ^ CH , ^NH - NH-' and NH„ \y \/ NH -*• I I /\ I' |CH:, ij-H„ \y This base gives azo-colouring matters very similar in dyeing properties to benzidine Other bases are : — Dianisidine, obtained in an exactly similar way to tolidine from o-nitroanisol, NO., NHo NH I I /\ \ /OCH3 ^|0CH3 1^^ This base gives azo-dyes which dye cotton a much bluer shade than the above bases, and Dichlorobenzidine, obtained by chlorination and subsequent saponification of diacetylbenzidine, and also by the above-described process, from o-nitrochloro- benzene NH, On - '> - Kf NO2 NH I NH I I, 'CI The only example of au unsymmetric base which is used on the large scale is ethoxybenzidine, which is obtained as follows : — 2 2 SYNTHKTIO DYESTUFFS. ( 1 ) IMienol is sulphonated to the ;;-sulphonic acid OH OH - V S03H (2) diiizobenzone chloride is combined with this OH OH C.,H,N,C1 + (^ ^ l-'^lNAHs SOyH SO..H and (3) the product is ethylated, yielding benzeueazophenetol sulphonic acid OC-jHj An.ah, SO.,H This by alkaline reduction yields the hydrazo-compound OC,H, ^NHNHC,;H, SO,H and, with acids, ethoxybenzidinc nionosulphonic acid NH., SO3HI |OCoH, which, on heatiny: with water to 170° C, yields ethoxybenzidinc OCA J—, . I- H.SO, NH,(^ \-<^ />NH, Reactions of the anii R. N,C1 + 2H._,0, and will be fully dealt with later. AMIDO-COMPOUNDS. 23 The following reactions of these diazo-salts are important : — (1) R. N.,Cl + H20(hot)-5- R. OH + HCl + N,. on heating (2) R. N.J ■> R. I + N.,. (3)fR. NoCl + CHjOH-* R. OC„H, + HCl + N„. or I R. n",C1 + C JH^OH -> R. H + N, + CH.CHO + HCl. (4) R. NoCl -*• R. C1 + n',. -1, ,, f., ,. ^ ' -_ „ ,- f lu the presence of the corresponding ^'' ^-^.W "'^•nx^^r f cuprous salt. (6) R. N,,CN -^ R. CN + N2. J ' Reactions 4, 5, aud 6 are known as the Sandmeyer reactions and are of general application. The amido-compounds may be converted into nitro-compounds on nitration, or into sulphonic acids on sulphonation. Thus aniline, C^H^NHj, on nitration as acetanilide, CuHjNH.COCHj, yields 0- and j>nitracetanilide, which give the corresponding nitranilines on hydrolysis. By nitrating benzylideneaniline, C^HgN : CHC^Hj, the para-derivative is almost exclusively formed. ;/»-nitraniline is produced from m-dinitrobenzene by reduction with a mixture of sodium sulphide and sulphur. The most important sulphonic acid of aniline is the para-compound NH., and this is prepared by the direct treatment of aniline with sulphonic acid, or, better, by the action of heat on aniline sulphate (see p. 204). By the action of methyl alcohol and hydrochloric acid on aniline, the important dimethylaniline C,;HjN(CH3)o is produced, which on treatment with nitrous-acid is converted into ^-nitrosodimethylaniline N.(CH3), NO largely used in the preparation of dyestuffs. The considerable importance which has recently been acquired by those sulphur colours which are prepared from diphenylamine and its derivatives cause this substance to be of great technical interest. Diphenylamine is prepared by heating aniline with aniline hydrochloride under pressure, C6H5NH2.HC1-1-C6H5NH2 -» CgH^NHCeHs-i-NHiCl, and derivatives of it may be prepared by heating together any nitro-compound containing a halogen atom in the ortho-position to the nitro-group with a primary amine in the presence of sodium acetate, thus NO„/~Nci + HJl/^OH -> 0,N<;^~N— NH— /~\0H + HCl I n NO, NO, 24 SYNTHETIC DYESTUFFS. AMIDO-COMPOUNDS (NH,). {Naphthalene Series.) The remarks already made concerning the formation of the amido-compounds of the benzene series ap])ly also to the derivatives of naphthalene. Since by the nitration of naphthalene only a-derivatives are formed, a-naphthylamines alone can be formed by their reduction. Thus anitronaphthalcne yields a-uaphthylamine, NO.J NHj + 3H.,^ 111 + 2H,0 /3-naphthyl amine must therefore be made by other means, and is formed by heating /j-naphthol with ammonia, Both these amines yield, on treatment with nitrous acid, diazo-salts which are of considerable importance in the dyeing industry. Preparatiini of diazo-salts. — The preparation of solutions of diazo-salts on the small scale is fully described in the examples giren on pp. i'L'G-2-tO, but there are a few points which may be with advantage indicated regarding the diazotisation of amines and diamines as carried out technically. The first stage of the process consists in bringing the amine into solution, or at any rate into a finely divided state. In the case of such substances as aniline, toluidine, etc., this is easily attained by adding the right quantity of hydrochloric acid and water. Solids, such as the najihthylamines, benzidine, tolidine, etc., are mixed with liot water at 50-60°, and easily dissolve on adding the calculated amount of hydrochloric acid. In the case of a few other substances, e.;/. diauisidine, it is usual to take boiling water. In many cases the addition of the further (piantity of hydrochloric acid necessary for diazotisation produces a precipitate of the hj'drochloride of the base (as a rule the hydrochloride is much more soluble than the sulphate, so that hydrochloric acid is generally used), and for this reason such addi- tion is postponed till the solution has been cooled for the diazotising process. Addition of acid now precipitates the hydrochloride, but in a much more favourable condition for being acted upon by nitrous acid than if it were brouglit down while still liot. In the case of aniline and bases whose hydrochlorides arc easily soluble in water, the whole of the acid necessary may be added at once. In whatever way the solution of the liydroohloride is prepared, it must be considerably cooled before conversion into the diazo-salt. Even in the prepara- tion of diazo-salts which are very stable the solution must be cooled, in order to prevent the escape of nitrous acid. Generally speaking, when diazo-salts are relatively unstable, e.g. the diazo- chlorides of benzene, toluene, xylene, etc., the solution should be cooled to C. and not allowed to rise above 4-5° C. A considerable amount of heat is evolved when the sodium nitrite is run into the acid solution, so that lumps of ice should always be present during the process. In the case of more stable salts, such as the diazo-chlorides prepared from benzidine, tolidine, diauisidine, etc., the AMIDO-COMPOUNDS. 25 starting temperature may be 8-10° C, and the final point 15° C.^ The amount of hydrochloric acid which is necessary for diazotisation is, according to the equation X. NH., + 2HCl + NaN02=X. N„C1 + NaCl + 2H.,0, two molecules to one of the base. A considerable excess of this quantity is, however, taken in practice, as otherwise a diazoamido-compound is formed. The usual quantity is two and a half to three molecules to one of the base (or NH„ group), but occasional!}' sis or seven molecules of acid are necessary to prevent the formation of the precipitate of diazoamido-compound (as in the case of /(-nitraniline). The actual diazotising process is very simple ; it only consists in running in a solution of the calculated quantity of sodium nitrite till a reaction is obtained with iodide-starch paper after the solution has been stirred for five to ten minutes. The diazo-solution should be quite clear and free from foam. In certain cases where an insoluble base has to be diazotised, it is usually stirred for a long time with acid and excess of nitrite solution till the diazotisation is complete. This is not, of course, ascertained by the use of test paper, but by observing the change of colour, solubility, etc., of the substance under treatment. The diazo-compound is then usually coupled with a component, as in the preparation of azo-dyes ; or is added slowly to a boiling solution of sulphuric acid (in the decomposition of the diazo-salt prepared from naphthionic acid, the filtered yellow diazo-compound is stirred up with water before running into the hot acid), in order to replace the group N.,C1 by the OH group. Constitution of dia::o-salts.- — The first theory of the constitution of the diazo- salts, and one which has held its ground till quite recently, is that proposed by Kekule (1866), according to which the constitution of diazobenzene chloride is CsH,.N-:N.Cl. The chief arguments in favour of this mode of writing the diazo-salt being (1) its simplicity and (2) its easy explanation of the formation of hydrazines by reduction, thus : — CsHjNiNCl-f 4H = CeH5N - NCI. H H3 In the year 1894 the discovery of metallic diazo-derivatives by Scbraube and Schmidt gave a new impetus to work in this field, and it was soon found that two classes of metallic diazo-oompounds of the formula CsH^N.jOK exist. These were at first considered to be structurally difTerent, but the researches of Hantzsch leave little doubt that such compounds are geometrically isomeric and representable by the formulse CeH^N II and CoH.N II KO.N N.OK S2/?i-diazo-oxide a?j<«-diazo-oxide. The increased attention given by chemists to this branch of organic chemistry, and the study of the whole range of diazo-compounds, led to the re- ' For a comparison of the stabilities of ditfereut diazo-salts used technically, see Cain and Nicoll, J.C.S., 1902, Ixxxi. 1412 ; 1903, Ixxxiii. 206, 470 ; also J. Sor. Dyers, 1902, April No. ''Morgan, "Our Present Knowledge of Aromatic Diazo-Compounds," Brit. Ass. Reports, 1902. Hantzsch, Die Diazoverbindungen, 1902. Eibner, Ziir Geschichte der aromcUisclieii Diazoverbindungen, 1903. 26 SYNTHKTir DYESXrFFS. introduction (by Hantzsch) of the formula for cliazo-sa//s which had been advocated by lilonistraud (1869), Strecker (1671), and Krlenmeyer, sen. (1874), in which the resemblance to the ammonium compounds is emphasised, viz. : — /^Hj N C^^r -> CoH,N, \C1 CI (aniline hydrochloride) benzene diazonium phenyl ammonium chloride, chloride, the name diazonium being used to indicate the analogy with the ammonium compounds. The above theory demands the existence of three varieties of diazocompounds, which, in the case of the cyanides of diazotised j:>-anisidine, have all been pre- pared in the pure state by Hantzsch, thus: — R. N.CN R. N R. N Hi II II N CN.N N.CN diazonium cyanide .s-^/K-diazocyanide a;(//-diazocyanide. According to Hantzsch the combination of the diazonium salt with a component with formation of an "anti " azo-colouring matter involves the formation of the intermediate, labile, .-.v/ji-colouring matter, tliu.s : — R CsHj.OH R C.Hj.OH R N=N + -^ N = N -> N = N CI H Cl-H C,Hj.OH. The diazonium theory of diazo-saUs may l)e said to have slow!}- replaced that due to Kekule, although many text-books of recent date retain tlie old method of writing the formula of these compounds.' ' It has recently been suggested (Cain, " The Constitution of the Ammonium Compounds," Mttiieh. Memoirs, 1904) that diazobenzene chloride should be written CeH,N< I ^•01 corresponding to a new formula for ammouiuni chloride, viz., H3N-CIH. CHAPTEE V. HYDROXYL COMPOUNDS (OH). (Beiizene Series.) The hydroxyl group may be introduced into the benzene nucleus in a number of ways, of which the following two are the most important : — (1) By fusing the sulphonic acid, or its alkali salt, with caustic soda, R. S03Na + 2NaOH -> R. ONa + NaoSOa + ILO, giving rise to the alkali salt of the phenol, sodium sulpliite and water. (2) By boiling the diazo-salt of the amine with water, R. NaCl + HjO -> R. OH + N^ + HCl. An example of the first method is the production of resorcinol (??«-dihydroxy- benzene) by fusing benzene Hi-disulphonic acid with caustic soda. The second method is used for the preparation of Neville and Winther's acid (a-naphthol-4-sulphonic acid) from naphthionic acid NH., By the nitration of phenol, nitro-phenols are formed, which, on reduction, give the corresponding amidophenols. The most important of these are the dialkyl ?»-amidophenols OH /\ which are largely used in the preparation of the Rhodamines. Phenol, on treatment with sulphuric acid, is converted into the phenol sulphonic acids, the ortho- and para-derivatives OH OH SO^^H being formed. These find employment in the manufacture of several azo-dyestufts. Reactions of the hijdroxyl group. — CJnlike the aliphatic hydroxyl group, the phenol group possesses marked acid properties. Thus with dilute caustic soda it is converted into a sodium salt, stable in aqueous solution. It is not, however, a sufficiently strong acid to decompose carbonates, and it is only by 28 SYNTHETIC DYESTUFFS. increasing the negative nature of the phenyl (C^Hj) group by the entrance of, for example, nitro-groups that the hydrogen of the hydroxy 1 becomes sufficiently acid for this purpose. Thus picric acid, (C^H.,(NOo))-jOH, made by the nitration of phenol, decom- poses carbonates. The hydroxyl group, together with the amido-group, forms a constituent of almost every dyestuff, and it sometimes happens that tiie acidic nature of this group has a bad effect upon the ch;iracter of a dyestuff in which it occurs. This defect is remedied by converting the phenol group (in the finished dye) into its alkyl salt, which can be readily done by treating ite sodium salt with alkyl halogen compounds. HYDROXYL COMPOUNDS (OH). (NaiMhalene Series.) The introduction of the hydroxyl group in the naphthalene series is also brought about by fusing the sulphonic acid with caustic soda. Thus the a- and ^-naphthalene sulphonic acids give a- and /3-naphthol OH I I I and f I P^ when fused with caustic soda. Like phenol, both a- and ;8-naphthol are weak acids, and react with caustic alkalies, forming stable alkali salts. By sulphonation they pass into sulphonic acids, an account of which has already been given. CHAPTER VI. CARBOXYL COMPOUNDS (COOH). The carbosylic acids of chief importance in the dyeing industry are those belonging to the benzene series. The carboxyl group may be introduced in a variety of ways, of which the two following are of importance : — (1) Oxidation of a benzene hydrocarbon containing a side chain. Thus toluene on oxidation with manganese dioxide and sulphuric acid yields benzoic acid, CsH-CHs + SO -* C^HjCOOH + aO. (2) The hydrolysis of the nitrile group. Thus benzonitrile gives benzoic acid (ammonium salt) C6H5CN + 2H2O -> O6H5COONH4 The most important carboxylic acids are : — benzoic acid, salicylic acid, gallic acid, phthalic acid, and tannic acid ; and since no general method can be applied for their production they will be described in detail. Benzoic acid, CgHjCOOH, is obtained either by method (1) or from benzotrichloride, CgHjCClj, on heating with water in the presence of an iron salt. Salicylic acid, C,;H4(OH).COOH (1 : 2), is prepared by Kolbe's method, that is, by passing carbon dioxide over heated sodium phenate, according to the following equations : — I. CjHsONa + CO., -> CiHjOCOONa. OH II C,iH,.O.COONa -> C,iH/ ^COONa ,0H /ONa III. C,;Hj< + CHsONa -^ CsH 4< +C6H,0H. \C00Na ^COONa A modification of this synthesis, which permits of the immediate conversion of all the phenol into salicylic acid, is known as Schmitt's synthesis. According to this method, the sodium phenyl carbonate is heated in an autoclave under pressure to 140°,. when it is completely converted into sodium salicylate accord- ing to equation II. Gallic acid is recovered by boiling gallotannic acid with dilute sulphuric acid. This latter, also known as tannic acid or tannin, is obtained from gall-nuts by extracting the powdered nuts with ether and alcohol, and dissolving the tannic acid from the extract by shaking it with water. 30 SYXTHKTIC DYESTUFFS. Fhthalic acid X3i COOH OOH was formerly produced by oxidising iKiiiiitlialciie or its derivatives with nitric acid or cliromic acid. It is now, however, prepared by treating naphthalene with sulphuric acid in the presence of mercury. The sulphuric acid plays the part of an oxidising agent, and is itself reduced to sulphurous acid (D.P. 91,202), and the phthalic acid is obtained in the form of its anhydride. Phthalic anhydride is extensively used in the preparation of the phthaleines (see p. 250), and also in the preparation of artificial indigo (see p. 163). KETONES (CO). Very few of the aromatic ketones find any application in the preparation of dyestufFs. Probably the most important are those derivatives of benzophenone which are used in the production of the compounds of the triphenylmothaue series, of which tetramethyldiamidobenzophenone ^CsHjNlCH.).. C0< NjeH^NCCH,), is a tj'pe. This substance is prepared by the action of phosgene (COCL) on dimethyl- aniline. The first product formed in this reaction is evidently dimethylamidobenzoyl chloride ^Cl C„H,N(CH3)„ . C„H,N(CH3).. co< + " -> co< \C1 \C1 ^HCl which reacts further with dimcthylaniline to form the ketone (1) (1) /CeHjNCCHj)., CiH.NiCH,)., CO< " -V C0( ■ , HCl. \C1 + CeH^N^CH,)., ^C^.NiCS.,).. (1) (4) " Tetramethyldiamidobenzophenone on red\iction yields tetramethyldiamido- benzhydrol (1) (■)) ,CoH^N(CH,)., CHOH< \C„H,N(CH3\, (1) (4) " which is also used in the preparation of compounds of the triphenylmethaue series. This secondary alcohol may be also (and better) prepared by the oxidation of tetramethyldiamidodiphenylmethane CH.,( "\0,H,N(CH3), CARBOXYL COMPOUNDS. 31 which is formed by the condensation of formaldehyde and dimethylanihne (1) (4) CeH5N(CH3)., yCeH.JS[{CH.s]. ch:.o+ " -* CH.< '+H„0 CgH^NlCH..).. ■\C,;HjN(CH3)., (1) (J) ALDEHYDES (CHO). The most important aromatic aldehyde used in the manufacture of the dye- stuffs is hemaldeliyde. It is prepared by heating benzyl chloride with lead nitrate and water (1), or by heating benzal chloride containing benzotrichloride, CgHjCClj, with milk of lime (2) (1) C,;H5CH.,Cl + -5. CeHjCHO + HCl (2) CfiHsCHCL + CaCOH)., -* CgHsCHO + CaCl, + H.p and is used for the preparation of Malachite green. The nitro-dcrivatives of benzaldehyde are of considerable importance. m-Nifrobemiildeht/de /NO., (3) \CH0(1) is the only one easily prepared by direct nitration, and gives, on reduction, ?7i-amidobenzaldehyde, which, on diazotisation and boiling with water, is con- verted into m-oxybenzaldflnjde /OH (1) c,h/ ^CHO (3) used in the preparation of dyestufFs of the Patent blue type (see page 80). o-Nitrobenzaldelujde is utilised in the preparation of artificial Indigo (M.L.Br.). It is prepared [Homolka) by condensing o-nitrobenzyl chloride ,.CH,C1 (1) \nO„ (2) with aniline to form the benzyl derivative ^CH.,.NHC^H,(1) CfiH/ \nO; (-2) which, on oxidation, is converted into o-nitrobenzylidene aniline /CH:N.CsH5(l) CcH/ \NOo (2) giving, on hydrolysis with acids, o-nitrobenzaldehyde and aniline ,CH : NCeH, /CHO aH,< +H,0 -> C^h/ -hC,H,NH, \nO., " ^NOo The Gattermann processes for the preparation of aldehydes are of exceptional interest. One of these consists in passing dry carbon monoxide and hydrochloric acid gas (at 60-70° C.) through a mixture of cuprous chloride and aluminium 32 SYNTHETIC DYESTDFFS. cliloride witli the aromatic hj'drocarboii into which it is desired to introduce the aldehyde group. The mixture of carbon monoxide and hydrogen chloride apparently reacts as the non-existent forniyl chloride, which, like other acid chlorides, reacts on the hydrocarVion according to the equation : H : C.H.:H + • .01 -> C,H,CH0 + HC1 " ; ■ CO Another process consists in treating phenols witii hydrocyanic acid and hj'drochloric acid in the presence of aluminium chloride. The products first formed are aldimidcs (containing the group - CH : NH), which are dissociated by the action of hydrolytic agents into the aldehyde and ammonia. This method gives better results in the naphthalene series than in the benzene series, and has been used by its inventor in the preparation of a number of important aldehyde derivatives of uaiihthalene. It has also been found (B.A.S.P'.) that the aldehyde group can be introduced by the oxidation of the methyl group (CH3) contained iu aromatic hj'drocarbons. Thus toluene can be converted into bonzaldehyde by oxidation with manganese dioxide and sulphuric acid. The ortho-sulphonic acid of benzaldebyde /CHO (1) cm/ \S0,H (2) is used in the manufacture of dyestuffs of tlie patent blue class. It is prepared by oxidising stilbenc sulplionic acid ,CH : CH-CuHiSO.,H C,;H/ \SO3H with potassium permanganate. Formahlphyilf, CH.,0, owing to the many reactions into which it enters, is the most important aliphatic compound used as an intermediate product. It is also used under the name of formalin (40 per. cent, solution) as a disinfectant. The method of preparation consists in oxidising the vapours of methyl alcohol by atmospheric oxygen, in the presence of an oxygen carrier. Plwsijenn, COCl.,, is formed by passing carbon monoxide and chlorine over animal charcoal in the presence of a cooling mixture It is used in the preparation of the ketones described on p. 30, which are employed in the manufacture of dyestuffs of the triphenylmethane series. § 2.~THE DYESTUFFS. CHAPTER VII. APPLICATION OF THE DYESTUFFS. Many theories have, from time to time, been brought forward having for their object the ehicidation of the nature of dyeing. Among these may be mentioned : — (I.) The mechanical theory. (II.) The chemical theory. (III.) The solid solution theory. (IV.) The absorption theory. None of these, however, satisfaotiirily explain the facts, and the nature of dyeing must be regarded as still but little understood. The viefhaniccd theory supposes a purelj' mechanical absorption of the dyestutf by the "pores" of the fibres, which, on being closed by astringents, retain the colour. The chemical theory supposes a direct combination between the dye-base and the fibre, which is (in the case of wool) presumed to possess both acid and basic properties. One of the chief facts in support of this theory was that discovered by Knecht, who found that, when Magenta (hydrochloride) was boiled in aqueoiis solution witli wool, the whole of the hydrochloric acid remained in the bath, whilst the dye-base (colourless) combined with some acid constituent of the wool to form the colour. Since then, however, it has been shown that the rosaniline base in one of its forms is coloured, and that the dissociation of the rosaniline hydrochloride is completely brought about by boiling its aqueous solution with such inert substances as glass, etc. As a matter of fact, the laws of chemical combination are not followed in dyeing, and the theory cannot be regarded as adequately expressing the facts. The solid sohdion theory supposes that the fibre plays toward the dyestuff the part of a solid solvent. Here, again, however, the laws of solution are not generally obeyed, and the theory must be regarded as inadequate. The absorption theory, recently proposed by v. Georgievics, states that "dyeing is a phenomenon of absorption, the dye being retained on, and in, the fibre by adhesion." For an account of this theory the reader is referred to Prof. v. Georgievics' Chemicid Technoloijy of the Textile Fittret', translated by Ch. Salter, p. 130. The classification of the dyestutfs from the practical standpoint, as mentioned in the previous chapter, is best considered from the point of view of their behaviour towards the various fibres. 34 SYNTHETIC DYESTUFFS. colours fixed bro by I albu- n, etc.). 1 .S O *^ a Group V stuffs cau! here mecha the fibre. Albumen (dyestulV on the fi means of men, casei >■ >>'is S' 00 1 — a S. •< 1 n3 o o 13 a" o 1 2 2 -o II 1 3 o g <£5 1 Metals. 1 Insoluble com]iounda 1 Mineral col 1 Indigo and phenol. 1 Aniline bla "1 6 cs Ig Q ail Cft O ri (N CO ^ C- SS 2. 2- Si (N -§ _c stuffs etc.). enyl- iill's. none- stuffs Thi- lines, s rg-S ;o-dye dine, triph 1 dyest he qui dye nes, Oxas 3tC.). ■^4 a 3 < jl « ji Basic az (Chrysoi Di- and methane Mostoft imide (Indami; azines, Azines, ( 3 V ;5 >> c-o 3 a 3 .5 s s>> o » r^ Q ^^ -'■' — ^ * — Ii from (deri- benzi- estuffs tc.). atural Bitters, tuffs. s 2 :^.i Dyestuffs tetrazo-salts vatives of dine, etc.). Thiazole dy (Primuline, e Certain n colouring mi sulphine dyes < 2 ii C 3 ° OO kt S? «" S" c -— ^-' -— _ estuffs ■ollow, ellow, and dye- eimide Gallo- o-a ^ o ^ o (2 -S ""^ - o - c o If 3 - '?'H A 7 1 .s X o U - 3 c N *3 a; -^ — .. > (U ^ >i ^ 3* ^ 5 =■^■3" go 5<^ --. § = |1 ■O 3 1 Gro Dyestuffs metallic Certain (Alizari Diamor Azarine Oxyquin quinone stuffs. Some dyestufi cyanine Oxyketo and stuffs. .2 :.> a-a 3 a 3 o" a> < i ' 1 "^ v_^ ^— ' ' ' '—' i estuffs zoxy-, tulis). of the ne, In- noline ndigo- 3l c 1 !-;.£•- ;o-dy dyes cids letha [Qui - I ^ Nitro-dyest Most az (amidoazo- and disazo- Sulphonic a trii)henylni duline, anr; dyestulls ■ carmine. 1 CJ P3 ^ .Si 1 <5" Hydrazonc azolone d. Chromotro belong t group). Ct N m 1 ^^ >^ APPLICATION OF THK DYRSTUFFS. 35 They may in this way be divided into six classes : — (1) Acid dyestuffs. (2) Basic or tannin dyestufts. (3) Dye-salts or substantive cotton dyes. (i) Mordant dyes. (.5) Vat dyes. (6) Developed dyes. The term substantive dyes means that the dye possesses direct affinity for the particular fibre to which it is substantive. The term adjective means that it has no direct affinity for the particular fibre, but that it can be affixed to it by the acid of some third substance, i.e. a mordant. (1) Acid dyestuffs are the sodium salts of the sulphonic acids, as well as of such dyes as certain phenol groups associated with nitro-groups. They are substantive to wool, upon which they affix themselves from a bath acidified with potassium hydrogen sulphate or dilute sulphuric acid. They form lakes with tannin, and hence can readily be distinguished from the basic or tannin dyes. They have little affinity for cotton, and are rarely used for dyeing this fibre. (2) Basic or tannin dyestuffs, — These are mostly colour bases with hydro- chloric acid or zinc chloride. Although they are substantive to wool and can be readily affixed to this fibre, yet they are, at the present day, almost ex- clusively used for the printing of cotton on a tannin mordant. Wool takes up the basic dyes in a very uniform manner witliout the aid of any addition to the dye-bath. Cotton. — The basic dj'estuffs are to a certain extent substantive to cotton, but the colours obtained are extremely fugitive, and of little practical importance. The best method of dyeing cotton with these colouring matters is first to prepare the material with either (a) Tannic acid and tartar emetic, (/j) A fatty acid salt of alumina. In either case the colour is produced by heating the mordanted cotton in a bath of the dyestuff' at 60° C. for half to one hour. The use of a fatty acid salt of alumina instead of tannic acid and tartar emetic in some cases produces a very marked difterence in the colour of the dyed material. Thus the Rhodamines, when dyed on a fibre mordanted with tannin, produce a dull lilac shade ; whereas the corresponding dyeings on a cotton impregnated with a fatty acid are of an extremely brilliant shade of pink, closely resembling the colour produced by the action of the Rhodamines on wool. The fatty acid used for this purpose is known as Turkey-red oil, a description of which will be given luider the head of the uiordant colours. (3) Direct or substantive cotton dyes (salt colours). — The discovery of the direct cotton dyes in 1SS4 by Bottiger caused a revolution in the cotton- dyeing industry. They are for the most part azo-compounds derived from benzidine I CeH^NHj or from bases which are similar to benzidine in tlieir constitution. 36 SYNIHKTIC DYESTUFFS. A further description of them will be given under the head of the azo-dyes, and it is only necessarj' to mention here that the relation between the property of a dyestuff of aftixing itself directly on the cotton fibre and its constitution is not yet clearly defined. The substantive cotton dyes are surpassed in brilliance by the basic dyes and in fastness by the mordant colours ; moreover, they are more susceptible than these to impurities in the material and to injury during the finishing processes. Many of the substantive cotton dyes are better adapted for the dyeing of wool than of cotton. The method of their application is the same as that of the acid dyestuffs. (t) Ingrain colours. — It frequently happens that the substantive dj'estufT employed for the dyeing of the cotton libre contains a free amido-group, which is, in many instances, capable of further diazotisation. When this is the case, the absorbed dye may be treated directly on the fibre with nitrous acid, which, con- verting the amido-group into the diazogroup, causes it to combine with any naphthol or amine capable of serving as a second comiioncnt. In this way fast shades of colour can be produced. (5) The mordant dyes consist of a largo number of very dill'crcnth' consti- tvited dyes, all uf wliich possess an acid character, and are indebted to the presence in their molecule uf hydroxyl or carbo.xyl groups for their property of forming lakes with mordants. The methods by which the mordant colours can be affixed to the fibres are very diverse, depending (1) upon the natureof the dyestuff and (2) upon the fibre. It is proposed here to deal merely with a few typical exami)les. ]\'(jo/. — It is in the dyeing of wool that the mordant dyestuffs receive their most important application. Rotighly speaking the methods are of two kinds: — (a) Dyeing previously mordanted wool. {b) Dyeing in a single bath. Coiton. — The most important application of the mordant dye to cotton is iu the dyeing of Tmkey-rcd. This colour, which has been kuuwn from the earliest times, is produced on the cotton Kbre by the interaction of alizarine, ahuuina, lime, and fatty acid. The exact chemical nature of the process is not yet dclinitely understooil, although it has been fomid {liofenstield) that the formation of the lake from alizarine and alumina cannot take place except in the presence of lime, a fact which was confirmed by Liechti and Suida, who found that all Turkey-red dyeings contain lime. The part played by the Turkey-red oil is still obscure. (6) Vat dyes. — To this class belong Indigo, Indophenol, and to a certain extent the sulphur colours. The dyestufls are insoluble in water, and therefore cannot be used directly for dyeing. However, on reduction, they are converted into " leuco "'-compounds, which are soluble in dilute alkali, have (in this condition) a marked affinity for the fibre, and further possess the property of being nadily reconverted into the dyestuff by the action of weak oxidising agents. Consequently, in order to dye with these compounds it is only necessary to impregnate the fibre with the reduced dye in alkaline solution, and by ex- posing it to the action of the air to cause the reoxidation of the leuco-compound to the insoluble dyestufi", which then remains firmly fixed in and on the fibre. APPLICATION OF THE DYESTUFFS. 37 (7) The developed dyes, as their name implies, are developed on tlie fibre by the interaction ot the constituents which produce them. They may be divided into two classes : — (a) The ice-colours. (6) Aniline black. (a) The ice-colours are produced on the cotton fibre by the interaction of some second component (witli which the fibre has been impregnated) with a solution of a diazo-salt cooled with ice. The nature of the amine varies the colour considerably, as is shown by the following list : — With /3-naplithol. /-nitraniline .... 02N<^ /NH.^ Scarlet. a-naphthylamine Bordeaux (claret). Benzidine Brown. Dianisidine ^OCH, Blue. /'OCH, (b) Aniline black is the black formed by the oxidation of an aniline salt, and may be produced either by oxidising a fibre impregnated with an aniline salt, or by heating the fibre with a solution of an aniline salt containing an oxidising agent. The Jird and older method is performed by padding the fibre with a solution of aniline hydrochloride containing the oxidising agent (potassium chlorate) with ammonium chloride and a salt of vanadium (oxygen carrier), the black being developed by the process known as ageing, which consists in subjecting the impregnated fibre to the action of air at a moderately high temperature. The second mefJiod consists in dyeing the fibre in a bath containing aniline hydrochloride, potassium bichromate, and either hydrochloric or sulphuric acid. CHAFTEI! VI 11. CLASSIFICATION OF THE DYESTUFFS. TuK largo iiuiiiber of ortratiic liycstiitt's wliicli have liecn syiuhetically ]>repared show tliat tlie dyeing property is dependent ii[ion structure, and that the dye- stuffs belong to certain well-deHncd classes of organic compounds. This has been expressed by (). N. AVitt in the following way : — (I.) The character of a dyestuft is derived from some group contained in it, which he calls the " chromophore." (11.) The fundamental substance containing the chromophore lie calls the " chromogen." (III.) The "chromogen" is not a dyestufl", but is converted into this by the entrance of some salt-forming group which destroys the chemically inert character of the chromogen. The best example illustrating this generalisation by AVitt is aniidoazo- benzene, C^-H.,N : N.C.H^NH.^. Here the chromophore group is the azo-grou]), -N = N- ; the chromogen is azobeuzene, CuH^N : N.C,.,H.,, which is not a dyestuff, but becomes the base of one by the introduction of the amido-group, which confers salt-forming properties upon it. The groups which confer salt-forming properties upon the chromogen are usually tlic amido-group (NH._,) and the hydroiyl group (OH), and these are termed by Witt the "auxochromes." Speaking generally, only those organic compounds which contain either acid or basic grou|)s can be dyestuffs. Furthermore, they are " unsaturated " compounds, and are readily reduced by nascent hydrogen, passing cither into " leuco "-compounds, which yield the dj'estuff again on oxidation, or breaking up into bodies of lower molecular weigiit, which are not reconverted into the dyestull' by oxidation. This important behaviour of the dyestull's will be again referred to, since it is used as a means of identifying them, both on the fibre and in their solid state. The theoretical classification of the dyestufTs is based u])on the generalisation by Witt above referred to, that is to say, according to the chromophore group occurring in them. For practical purposes, however, it is far more convenient to classify them according to their behaviour on dyeing the textile fibres, and this method will be adojited in dealing with their experimental a]iplication in a later chapter. CLASSIFICATION OF THE DYESTPFFS. 39 The classification, according to structure, divides them into the following chief groups : — Name of Dyestuff Group. Chromophore. Typical Dyestutf, O (1) Nitroso or oxime (2) Nitro =o- NO, \/=0 II NOH (Resorcin green). OK SO^Kj^^NO., NO., (Naphthol yellow S). (3) Azo («) N = N- -N;N-/ (salt). (b) = / N— NH-N=/ \=0 (free) (^-oxyazobenzene). (4) Triphenyhnethane /^ >NH., /^ = NH.HC1 (Magenta). (5) O.xyketone (mordant) CO OH CO (6) Pyronines Cl(R)J!f.> /\/\/^/N(R)2 I I I I C I^OOOH (Rhodaniine). 40 SYNTHETIC DYESTUFFS. Name uf DyestuH' Group. Cliromophore. Typical Dyestuff. (7) Diphenj'lainine (ii) Indamiues . H^^^O^, NH.HCl (Phenyleiie blue). (c) Tliiaziues ('/) Oxaziues . . I I I I (/') Indopheiiols . ' j ' ' (CH,i,JN ^ ^~'~0 (ludopheiiol blue). (Methylene blue). (Meldola's blue). CIH.HN ^^ if ^/ I (Safranine). Mordant dyestufFs. — The term monlant is applied to some substance which will form coloured /rt/re.< with dyesturt's. Thus the basic dyestuff Maf,'enta, which is readily absorbed by wool, has little or uo affinity for the vegotal)le fibres, but possesses the property of forming with tannic acid an insoluble coloured lake. Hence by steeping the cotton fibre in a solution of tannic acid, and subsequently fi.xing it in the fibre by means of tartar emetic (which forms an insoluble compound with tamiic acid), a veiretable fibre impregnated with a salt of tannic acid can be obtained, which, on boiling in a solution of Magenta hydrochloride, becomes coloured with the tannic lake of Magenta. Hence tannic acid is, strictly speaking, a mordant. The term, how- ever, has a somewhat more restricted mca;iing, and is applied to cerUiin metallic oxides which possess the property of forming coloured lakes with certain well- defined classes of organic compounds. It has been found {Liohprmann and i\ Ko.4'in>cH) that only those derivatives of anthraquinone which contain the hj'droxyl groups in the oitho-iiosition to themselves, and to one of the carboxyl groups of the chromophore, possess the property of forming lakes with the oxides of various metals, such as iron, tin, aluminium, chromium, etc. CLASSIFICATION OK THE DYESTUFFS. 4 1 The formation of these lakes can be brought about by steeping the cotton fibre in a solution of the acetate of tiie metal, which, on steaming, becomes impregnated with the oxide (owing to the decomposition of the acetate). The cotton thus mordanted, when boiled in an aqueous solution of the dyestuff, becomes dyed with the lake. The law of Liebermann and v. Kostaneoki is not of general application, and many instances are known which do not conform to it. Thereare, however, many ortho-derivatives, outside the alizarine series, which form lakes with mordants. Thus azo-compounds such as C^H-N : N.C|H,(OH)COOH prepared from salicylic acid and diazobenzene chloride, form lakes with metallic oxides, and thus compounds of this type, which are already dyestutt's, can be converted into lakes by treatment on the fibre with metallic mordants. This property is also possessed bj' certain of the nitroso-phenols ; thus naphthol green B (Cassella) is the iron compound of nitroso-/8-naphthol sulplionic acid /SOsNa SOoNa. / ' ^ \ C,„H,^0 0-C,oH5 \ 'NO-Fe-ONl / (See page 42.) CHAPTER IX. THE NITROSO-COMPOUNDS. (Uuimmoxiims.) Thb uitroso-phenols are produced liy the action of nitrous acid on tlie phenols, according to the equation H0<^\ + NOOH -> N0<^ ^OH . H.,0 The fact, however, that the same nitroso-phenol is produced by the action of hydroxylamine on p-quinone according to the equation = /~\ = + H2NOH -> = ^ ^ = NOH r KO quinone quinoneoxime shows that in all probability these substances can react as quinoneoximes, which better accounts for their behaviour as dyeing agents, since the quinone ring occurs in many dyestuffs as a chromophore. The value of the nitroso-dye more especially depends upon the property of the ortho-compounds of forming lakes (green) with iron. Tims Fa^t green or Resornn (jrein is dinitrosoresorcinol, which is produced by the action of nitrous acid on resorcinol, and therefore possesses the formula /\=NOH II NOH Xaphthvl gront B (Cassella) is the nitroso-conipound of sodium /J-iiaplithul mono-sulphonatc, and has the formula Other dyestuffs of this group are : — Gambin R [HI . o nitroso-a-naphthol. THE NITROSO-COMPOUNDS. 43 Gambin G or Y [H] ( Alsace green (J) ( ' I I a-nitroso-/3-naphthol. NOH Dioxin [L] Gambin B [H] nitrosodioxy naphthalene. These dyestuft's are only sparingly soluble in cold water, and are found in commerce either in the solid form or suspended in water (paste). CHAITER X. THE NITRO-COMPOUNDS. The entrance of the nitro-group into the molecule of the aromatic phenols causes them to become more or less pronounced d3'estufTs. The nitro-dyestufi's are, witliout exception, acid-dj-estuflfs ; that is to say, tliey are the salts of the various nitm-fiheiiols and nitro-naj)hthols (or their sulphonic acids) formed by the action oF alkalies on the strongly acid hydroxyl compounds containing nitro-groups in the same nucleus. Many of the nitro-phenols, as, for example, /Miitrophenol, are colourless, but in the form of their salts are coloured. o-Nitrophenol, on the other hand, is itself a coloured substance. It has been suggested {Aniistro7ig) that this diirerence between the ortho- aiid para-derivatives might possibly be due to a difference in structure. Thus for para-nitrophenol (colourless) he proposes the ordinary nitro - formula, OH.C.^H^.NOjj but for the yellow ortho-compound he considers the quiuoiie structure O OH the more probable one. The formation of coloured salts from /*-nitrophenol would, however, seem to indicate that this substance in the form of the free acid has the ordinary nitro- structure ; but that in the form of its salts it possesses a quinone structure represented by the formula O O CiH, N ONa The close analogy that exists l)ctwccn the nitro-ciimpounds and the so-called nitroso-dyestuffs renders it ])robable that a similar structure is possessed by both, and that the nitro dyestuffs are derivatives of quinone having for their cliromo- phore the quinone ring There is not, however, at present sufficient direct evidence to warrant this assumption, and it is better to consider the nitro-compounds as possessing the chromophore - NO,,, which, in conjunction with the salt-forming (auxochrome) group OH, furnishes the acid of which the dyestufl' is the salt. The nitrocompounds belong to the older artiiicial dyestuffs, and wore at one time very largely used by the dj'cr for the purjiose of dyeing wool and silk. Their fugitive character has, however, led in recent times to their replacement by the yellow azo-dyes. Most of them possess the proj)ertics characteristic of aromatic nitro-com- pounds; that is to say, their more or less pronounced yellow culour, liie ex- plosive nature of their salts, and their poisonous character. THE NITRO-COiMPOUNDS. 45 Typical examples of the nitro-dyestuffs are : — Picric acid, OH NO., which is the oldest dyestuff of the group, and is prepared by treating phenol sulphonic acid witli concentrated nitric acid. Although at one time of consider- able importance, it is at the present time but little used. iMartius yeltoio, the sodium, calcium, or ammonium salt of dinitro-a-naphthol OH NO, is prepared by the nitration of l-naphtliol-2 : 4-disulphonic acid, and was at one time largely used for the dyeing of wool. At the present time it is employed merely as a pigment colour. Naphthol yeUow S is the potassium (or sodium) salt of-2 : 4-dinitro-l-naphthol- 7-sulphonic acid OK and is the most important dyestuff of the group.^ It is prepared either (1) By the nitration of l-naphthol-2: 4 : 7-trisulphonic acid, or (2) By the oxidation of nitroso-a-naphthol disulphonic acid. Naphthol yellow is much faster than the other nitro-dyestuflFs, and is exten- sively used for dyeing the animal textile fibres. Another dyestuff of this group is : — Aurantia, NO.j|-^^|NO., NO.,!-^ '|N02 NO.^ -r* NO., NHj ammonium salt of hexanitrodiphenylamine. THE STILBENE DYESTUFFS. A;Mxy-di/esfuJfs. — To this group belong certain yellow to brown dyestufFs whose composition is not known with a very great degi'ee of certainty, but which are considered to be derivatives of Stilbene C,;H5.CH II C,iH,.CH and to contain the azoxy-group as chromophore •N— N- \/ O ' See Knecbt and Hibbert, Her., xxxvii. 3475. 46 SYNTHETIC DVESTUFFS. The method of preparation is to heat />-nitrotohiene sulphonic acid or dinitrodibenzyl disulphoiiic acid with caustic soda under various conditions of temperature, concentration, etc., either alone or together with amines, oxidising agents, etc. The most important dyestuffs of this group are Curcumine S, Sun yellow, tlie Mikado coloui-s, Stilbene j-ellow, and Direct yellow. The first two are obtained by boiling ;:<-nitrotulueiie sulphonic acid with caustic soda solutiun By using concentrated alkali, Curcumine S is obtained, while Suu yellow results by the action of dilute alkali. The Lonstitution of the latter is considered to be (See Green, J.C.S., 1904, Ixxxv. 14J4, 1432.) CHAPTER XI. THE AZO-DYESTUFFS. The azo-dyestuffs form a well-detiiied group of compounds which possess as chromophore the group - N = N - This divalent group attaclied to two aromatic nuclei forms the chromogen R. - N = N - R., which, by the entrance of tiie auxochrome (NH., or OH), Itecomes the base or acid of which the dyestuft" is the salt. I. General methods of formation. — Generally speaking, the azo- compounds are prepared by the interaction of a diazo-salt (first component) with an aromatic hydroxy-compound or amine (second component), the reaction proceeding according to the equation OH or /OH or R. N„C1 + R. -* R. N, R./ +HC1. NHo ■ NH„ (0.\;yazo- or amidoazo-compouiid.) The two chief methods of formation are as follows : — (1) The second component is a phenol (naphthol). The aqueous solution of the salt (hydrochloride) of a primary amine is first treated with sodium nitrite and hydrochloric acid in the presence of ice, whereby a diazo-salt is formed, CBH5NH,HCl + NaN02 + HCl -* CoHsNoCl + NaCl + 2H,0. The solution of the diazo-salt is next " coupled " with the phenol by allowing the solution of the former to run gradually into an alkaline solution of the latter. It is necessary to keep the solution alkaline throughout the addition, since the formation of the azo-compound is retarded by the jiresence of free mineral acid. When the dissolved diazo-compound has been mixed with the phenol, the whole is left for the reaction to attain completion, a point which is ascertained by testing a portion of the mixture for unchanged phenol by means of a solution of diazobenzene chloride. The dyestuff in some cases settles down as a sparingly soluble alkali compound ; in others it remains in solution, and can be recovered as a salt by precipitation with sodium chloride, or in the free state by the addition of acid. (2) The second component is an amine. The principle of the method is the same, except that the combination of the diazo-salt with the dissolved amine is brought about in neutral or faintly acid solution. 4^ SYNTHETIC DYESTUFFS. When the second component contains both a hydroxy! and an aniido- group, the constitution of the azo-compouiid obtained varies according as the coupling takes place in acid or alkaline solution. Thus in the case of amido- naphthol sulphonic acid y OH if diazotised benzidine be the first component, one obtains — In acid solution . . . Diamine violet. In alkaline solution . . . Diamine black. (See, however, p. .'il.) In the case of dihydroxy-compounds the coupling is often carried on in weak acid solution in order to avoid the formation of a disazo-compound (coupling with reference to both OH groups). The formation of the azo-compound is usually quantitative, and in the prepara- tion the calculated quantity of the constituents is used. The best method for preparing the solution of the diazo-salt is to take 1 mol. of the amine, 1 mol. of sodium nitrite, and 2A mols. of hydrochloric acid, the J mol. in excess being subsequently destroyed by the addition of the requisite quantity of sodium acetate, the free acetic acid tlius formed having no deterrent effect upon the formation of the azo-dyc. The stability of the diazo-salts varies considerably. In some cases they readily decompose into nitrogen and the corresponding phenols at temperatures above 10° C, and in these cases the diazotisation has to be effected in the presence of ice. Hence when working with aniline, toluidine, and other bases of this type ice must be used in their diazotisation. The diazo-sulphonic acids, such as diazo-sulphanilie acid and diazonaphthionic acid, are more stable, and can in many cases be prepared at ordinary tempera- tures (cp. J.C.S., 1902, Ixxxi. 1412 ; 1903, Ixxxiii. 206, 470). The diazo-coujpound of o-dianisidine is remarkably stable, and can be heated for a long time at 100° C. without undergoing complete decomposition (cp. J.C.S., 1903, Ixxxviii. 688). Stable diazo-compounds which can be stored in the solid state, and which can be easily used by the dyer, find considerable application, since they are used in the preparation of the " developed "' or " ice " colours. Many methods have been devised for their preparation. (1) The Badische Aniline and Soda Fabrik treat the diazo-chloride of para nitraniline NOj ,C1 with alkali, which converts it into a stable so-called nitrosamine salt (anti-salt), according to the equation /NO., NO., CjHZ ■ t 2NaOH -> CeHj< ' iNaCl + H.,0. ^NXl ^N.^N ONa THE AZO-DYESTUFFS. 49 This sodium salt they introduce under the name nitrosamine red in pade. It is quite stable luider ordinary conditions, and is quantitatively converted into the diazo-chloride on treatment with dilute hydrochloric acid /NO., .NO., CeH/ " +2HC1 -> C,;H/ ' +NaCl + H.,0. \N.=N,ONa \N.,C1 (2) The Hochst Farbwerke (M.L.Br.) obtain stable diazo-compounds by evaporating their strongly acid solutions at 45° C, and mixing them with indifferent materials. Azophor red PN is diazo-j)-nitraniline ; Azophor blue D, diazo-o-dianisidine. The diazo-solution can also be brought into the solid condition by mixing it with anhydrous aluminium sulphate. (3) L. Cassella & Co. (Frankfort-am-Main) effect diazotisation of ^;-nitraniline in concentrated sulphuric acid, and mix with sufficient anhydrous sodium sulphate to form bisulphate (nitrazol ('). II. Laws regulating' the formation of azo-compounds. — in coupling diazo-salts with phenols and amines of the benzene series, it appears to be a law that the diazo-group enters the para-position with regard to any hydroxyl or amido-group present. Should this position be occupied, the diazo-group enters the ortho-position to the OH or NH., ; and if this also is occupied, then either, as is most frequently the case, no formation of azo-couipound takes place, or the group occupying the para-position is displaced by the diazo-group. When phenols containing free ortho- and para-positions are coupled with diazo-salts in caustic alkali solution, a small quantity of an orthoazo-compound is formed in addition to the paraazo-compound. Diamido- and dioxy-derivatives of benzene also combine with diazo-salts to form azo-compounds ; but it has been found that this formation only takes place when the diamido- and dioxy-derivatives belong to the meta-series. Thus only wi-phenylenediamine and resorciiiol react with diazobenzene chlnride to form azo-compounds. The dyestuff produced from the former is named " Chrysoidine," and hence this generalisation is known as the "Chrysoidine law." This "law," however, only applies to the coupling of the diazo-salt under ordinary conditions, since it has been found {Witt and Johnson) that both pyro-catechol and hydroquinone can furnish azo-compound.s with diazobenzene chloride under suitable conditions. Speaking generally, the formation of ortho-, oxy-, and orthoamidoazo-compounds is desirable when the product is required for use as a dyestuff, since the paraazo-compounds are not so well adapted for this purpose. If, however, it is desired to prepare polyazo-com]iounds by the further diazotisation of an amidoazo-compound, then the combination must be effected in the para-position, since amido-groups in the ortho-position to the azo-gronp are for the most part incapable of reacting with nitrous acid to form diazo-salts. The laws regulating the formation of azo-compounds in the naphthalene series are as follows : — (I.) A hydroxyl group or an amido-group is in the a-position (1). Combination takes place in the position (4). If this is occupied, or if the positions (3) or (5) are occupied by sulphonic acid groups, combination takes place in the position (2). The cross indicates the position of the entering azo-group in the following compounds : — 50 SYNTH KTIC DYESTUKFS. The presence of tlie sulphoiiic acid group in any position otlier tlum (3), (4), and (5) causes tlie combination to take place in (4). This also applies to the disulphonic acid derived from a- and /i-naplithol and naphthylamine. (II.) A hydroxyl jrroup or amido-group is in the /J-position (2). Combination takes place in the jiosition (1) ; if this position is occupied, then no formation of azo-compound takes place. Thus /3-naphtliol and /^-naphthylamine combine with diazo-salts in the position indicated bv the cross. I ^ U\/^ Whereas diazo-salts only enter once into the molecule of /?-naphthol, a-naj)hthol combines with two molecules to form a "disazo-compound." In the compound thus formed the second azo-group enters in [losition ("J), forming a substance of the formula OH In many respects these " disazo-conijiounds " are similar to the substantive cotton dyes derived from benzidine and deacribod on p. 69. As in the benzene series, the ortlioamidoazo-componnds of the naphthalene series are of importance only as dyestuffs, the amido-group being incapable of further diazotisation. The amidugroup in the paraamidoazo-compounds can be further diazotised, and these are therefore largely' used for the preparation of dyestuffs containing more azo-groups. They are themselves, however, of little use as dyestufts, since they are readily acted upon by acids and alkalies with alteration of the colour. Both /3-naphtholiydroqiiinone OH OH I I [OH and its sulj)luuiic acid on trl I 1^^ form azo-dyestull's with diazo-salts. THK AZO-DYESTUFFS. 51 The amidonaphthol sulphonic acids in many cases react in different ways with diazo-salts, according as the coupling is carried out in acid or alkaline solution. Thus, for example, y-aniidonaphthol sulphonic acid OH gives in acid solutions an azo-comnound of the formula OH N = N-R. ^NH, whereas in alkaline solution the compound OH SO^H'xy^^ is formed. If, however, in this case, the combination of one molecule of diazo-compound has been effected (whether in acid or alkaline solution), it is impossible to intro- duce a second molecule of the diazo-compound. Such a formation of a disazo- dyestufF is, however, easily brought about in the case of the 1 : 8 acids, e.g. : — NH> NH^ SOjH'x /\ /SO H /SO3H SO; '^\ ) I, 'SO,H All these react with two molecules of a diazosalt, which combine in the position adjacent to tlie NH^ or OH group in each case. Diamido-, dioxy-, and oxyamidonaphthalenes and their sulphonic acids react in the following way with diazo-salts. The position into which the azo-group enters is in each case marked with a cross. 1 : 8-diamido- or Jioxynaphthalene OH OH NH, NH, '^ I I I |-^|^|NH, 0^/^|/^|0H NH/ I I- iNH, in acid or alkaline solution. 1 : S-diamido- or dioxynaphthalene 4-sulphonic acid OH OH XH, NHj 52 SYXTHKTir PVKSTUFFS. 1 : S diamido- or dioxyiiaphtlialene-3 : 6-disulphonic acid OH OH NH, NH. SO^n'-^^-'^y'sO.H SDH ^jx^'so^ The conditions ure various in the case of the aniidonaphthol sulphonic acids. Billow (C'heiii. Zli/., xix. 1011) divides them into the following classes: — (1) Such as are either incapable of being coupled at all, or, if so, only under special conditions. To these belong the sulphonic acids of the 1 : 2 and 2 : 1 amidonaphthols. (2) Such as are readily coupled and invariably yield the same product, e.ff. : — 1 : S-amidona]ihthol-5 : 7-disulphonic acid. (3) Such as give orthoamidoazo-compounds in acid solution, and ortho- oxyazo-dj'estufTs in alkaline solution, e.g. : — 1 : 8-amidonaplitiiol-3 : 6-disul])lionic acid (H acid) ; 2 : 8-amidonaphthol-6-sulphonic acid (y acid) ; and 2 : .5-araidonaphthol-7-sulphonic acid. Some of them — for example, 1 : 8-amidonaplitiiol 4- and 5-snlphonic acids — yield "disazo-dyestuffs " in alkaline solution. III. Abnormalities. — The reaction between diazo-salts and phenols or amines sometimes pursues an abnormal course. (1) Thus when diazobeuzene chloride reacts with aniline, the product does not consist of a true amidoazo compound, but, owing to the chlorine of the diazo salt interacting with a hydrogen of the amido-group, a diazoamido- compound is formed accoi-ding to the cipiation C,.H,N,, CI i H HNC.H, -; C„H,N : N.NHC.H^ + HCl. The same behaviour is exhibited by o-toluidine and by m- and 7)-xylidine. Diazoamidobenzene can, as Kekulc found, be readily converted into amido- azobenzene by heating it with aniline and aniline hydrochloride, the reaction proceedin;j: according to the equation C„H,N ; N ; NHCoHj + H i CsH^NH, -> C,H,N : N.C„H,NH, C,;H,NH,. The formation of diazoamido-componnds during the diazotisation of amines can usually be prevented by using a slightly acidified solution of nitrite. (2) Phenols containing nitro groups, and therefore of a strongly acid character, react in a similar way with diazo-salts. Thus picric acid, C|.,H„(NO.,);,OH, combines with diazobeuzene chloride to form the diazooxy-com))ound of the formula CjH.N ; N.O.C,iH,(NO,,),. (3) The interaction of diazo-sulphanilic acid and aniline hydrochloride pro- ceeds to a certain extent normally with the formation of the true auiidoazo- compound SO. SOH, CcHZ 1 +CcH5NH,.HCi -* ajax \N., " ^ N : N - C„H,NH., HCl At the same time, however, a curious molectilar rearrangement takes place with the formation of auiidoazobenzene. THE AZO-DYESTUFFS. 53 The equations repi'esenting the abnormal reaction are evidently the following : — SO, /SO,H \n.. ■ \nh„ (2) C„H5N.,Cl + C,iH5NH2 -> CgHsN : N.CsH^NH^.HCl. (4) lu the case of some derivatives of the amidonaphthols, an internal forma- tion of azo-compounds can be brought about by treating the diazo-salt with alkalies. Thus 2 : 8-amidonaphthol-6-sulphonic acid reacts in the following way : — OH OH / Y \jjjj diazotisation / N/\ti so^h'^^I ' " SO3: SO,H IV. Constitution. — The constitution of the azo-compoimds is mainly deter- mined by their behaviour on reduction. When treated with nascent hydrogen they split up at the point of union of the two nitrogen atoms forming one molecule of the base from which the azo- compouud was derived, and one molecule of the amido-derivative of the second component containing the amido-group in the position formerly occupied by the azo-group. Thus amidoazobenzene gives, on complete reduction, aniline and ^'-phenylene- diamine <^\n:N<' NnH„ -^ <(~^NH, + NH2^~\nh, This property, which is taken advantage of in the analysis of the azo-dye- stuflfs, will be found more fully described on p. 300. The action of concentrated sulphuric acid on the azo-compounds produces characteristic colours, which are apparently dependent upon the constitution. These colours are the same as those formed by the action of concentrated sulphuric acid on the azo-hydrocarbou which is the basis of the d3estuff. Thus azobenzene, CijHjN : N.Ci^H,-, dissolves in concentrated sulphuric acid, giving a brownish-yellow solution, and the same coloration is produced by the action of the concentrated acid in both amidoazobenzene, CijHjN : N.C^HjNH.,, and oxyazobenzene, C,.H,-N : N.C,;HjOH. a-azonaphthalene, Cj.jHjN : N.C,|jHj, dissolves in concentrated H^SO^, furm- ing a blue solution, and the same coloration is produced by its oxy- and amido- derivatives. In azo-dyestuffs containing both a benzene and a naphthalene ring, the behaviour towards concentrated sulphuric acid is the same. The presence of a sulphonic acid group, however, causes the substance to give different colorations according as the sulphonic acid group is in the benzene or naphthalene ring. Thus benzene-azo-^-naphthol, C,;H^N : N - Cj|,H,;(OH)/3, gives a red-violet coloration with concentrated sulphuric acid, presumably that of the azo-hydro- carbon, Cj.HjN : N.CjuHj. The same colour is produced when a sulphonic acid group is contained in the benzene ring. If, however, this group is in the naphthalene ring a yellow coloration is produced ; that is to say, the same as is formed by the action of sulphuric acid on azobenzene. 54 SYNTHKTTP DYESTTTFFS. With the polyazo-dyestiiffs similar cliaracteristic colours are produced. For example : — The azo-dyestuffs from give Amidoazobeiizenc sulphonic acids + ^-naphtho! .... green. Amidoa'zobenzene and honiologues + /i-iiiiphthol sulpiionic acids . red-violet. Amidoazobenzene sulphoiiic acids + /3-iiaphthol sul]ihonic acids . blue. Beuzeue-azo-a-naphthol, which is prepared Ity the combination of diazo- benzene chloride and a-naphthol, has presumablj- the forunila C,H5N:N.C,^0H, but identically the same coQipound is produced when a-naphthoquinone is treated with phenylhydraziue, which, from its method of formation, should have the formula Similarly, R. Meyer {Ber., 1888, xxi. 118; 1891, xxiv. 1243) prepared an azo-compound of malonic acid in the following way : — COOC0H5 COOC0H5 1 " ! CHNa T CIN.N.C.H, -> CH.N:N.C,H. ; NaCl I 1 coocja, coocSi ethyl sodio-malonate. 1 hjdiolN-sis COOH I CH.N ; N.C^Hs I COOH which was found to be identical with the hydrazone of mesoxalic acid prepared by Fischer and Elbers (Ann., 1885, ccxxvii. 355) COOH COOH 1 I CO -r- H.N.NHCfiH5 -> C ; N NH.C,H, - HO ! ■ I COOH COOH mesoxalic acid. Other instances of the same kind have also been noticed by Bernthseu (Ber., 1888, xxi. 743), and by Japp and Klingemann {A7171., 1888, ccxlvii. 190). The question therefore arises : Are the azo-dyestuffs true azo-compounds, or are they derivatives of quinone ? Taking oxy- and amidoazobenzene as two typical azo-dyestuffs, the two forms would be represented in the following way : — Azo-fonii. Qiiiiiiiiio or liylrazoiic fmni. C,.H,N : N - C„H.OH C,;H, NH. N : C„H, : O oxyazobenzene. phenyllij'drazone of benz(>i|uinonc. C„H,N : N CeH.NH, C,.H, NH N : C,;H^ : NH amidoazobenzene. phenylbydrazoue of quinoneimide. Whilst the oxj-azo-compounds, which cimtaiu the hydro.xyl group in the para-position to the azo-group, show all the properties of phenols, the corre- sponding derivatives containing the hydroxyl group in the ortho-position exhibit properties which are more in accordance with a liydrazone structure. THE AZO-DYESTUFFS. 55 Thus the azo-dyestuffs derived from /3-naphthol, and which contain the hydroxy! group in tlie ortho-position, are insokible in alkahes, and, therefore, do not possess phenoHc properties. In the same way, only the paraamidoazo-compounds behave as true azo-bodies containing a primary amido-group, for they can readily be diazotised, which is not the case with the corresponding orthoamidoazo-derivatives. For these reasons many chemists consider that the paraazo-compounds possess the true azo-structure, whereas the ortho-derivatives react as hydrazones, and although this assumption has much in its favour, yet it cannot be accepted as a true representation of the facts. Orthoazo-compounds frequently react as true oxyazo-derivatives, whilst, as mentioned above, an azo-compound is formed from a-naphthol (and therefore contains the azogroup in the para-position to the hydroxyl), which is identical with the corresponding hydrazone from a-naphthoquinone. Also acetyl and benzoyl derivatives can be formed from orthoazo-compounds which contain the acid radical combined witli the nitrogen atom (Goldschmidt, Ber., XXV. 2300 and 1324). On the other hand, Weinberg {Ber., xx. 3171) finds that acetylation of the hydroxyl group occurs in the case of the orthoazo-derivatives. From these divergent opinions it is evident that the two forms are tautomeric, and that both the ortho- and para-derivatives can react in either form. The question has been finally decided by Hautzsch [Ber., xxsii. 3089), accord- ing to whose researches both the ortho- and paraoxj'azo-compounds are hydrazones in the free state ; whereas their salts are true derivatives of oxyazobenzene. In the ensuing pages the azo-formula will always be the one adopted. V. The influence of groups and constitution upon the colour of azo-COmpoundS. — The simplest azo-dyestuflfs are yellow. Either by the increase in the number of chromophore groups, or by the increase in molecular weight, the colour deepens, pa.ssing either through red to violet or into brown. Azo-dyestufi's which contain only benzene rings are mostly yellow, orange- yellow, or brown. By the entrance of naphthalene luiclei reds are formed, and azo-dyestuffs containing only naphthalene rings are violet, blue, or black. Green azo-dj'estuffs seem only to be formed when nitro-groups enter into the molecule of the azo-compound. Mordant dyestuffs forming green lakes with chromium salts are, however, formed by coupling salicylic acid with the diazo- salts derived from certain compounds of the triphenylmethane series. Thus azo-green (By) is m-amidotetramethyldiamidotriphenylcarbinol azo- salicylic acid /CeH.NlCHj), C;^ C„H,N(CH,), 'j'°°^ OH - The sulphonic acid group entering into the molecule of an azo-dyestuff does not appreciably alter the nature of the colour ; it naturally, however, not only increases the solubility of the compound in water, but also causes it to become an acid dyestutf forming stable salts with alkalies. The introduction of sulphonic acid groups is sometimes effected in the finished dyestuff, but more usually they are present in the components which form the azo- compound. The position of this group is not altogether without influence on the colour of 56 SYNTHKTir DYESTUFFS. the dyestuff, as is shown by comparing the three isomeric compounds given below, which give three distinct shades of red : — OH Croceiu scarlet. Brilliant crocein. (1) SOjNav^ >N:N upon the colour of the azo-dyestuffs is clearly shown in tlie benzidine series (see iSiihstaiiHve cotton dyednff,, p. 70). Tetrazobenzidine ' salts combined with amidonaphthalcne sulphonic acids ' By tetrazubeuzidiiie salt is undei-stood ii tetrazo-salt of diphenyl, e.g. NoCl /<^ \ I \y I /\ I I \y N,,C1 wliich is, of course, derived from benzidine. This nouienclatuie is more customary than the more correct one, which, as in tlie case of the name " diazobenzene chloride," indicates the hydrocarbon from which the diazo-salt is dciivcd. THE AZO-DYESTUFFS. 57 yield red dyestuffs, with iiaphthol sulphonic acids blue dyestutl's, and in mixed combination (see p. 70) with both naphthylamine and naphthol sulphonic acids dyestutFs which are a mixture of red and blue, i.e. violet. Thus :— Tetrazobenzidine chloride + naphthionic acid (Na salt) give Congo red <^> Tetrazobenzidine chloride + Neville and Wiuthers acid (Na salt) give a reddish-blue dyestuff. SOjNa^ \0H OH<' NSOjNa <:> <_> Tetrazobenzidine chloride + 1 mol. naphthionic acid and 1 mol. Neville and Wiuther's acid give Congo Corinth (violet) ^ The entrance of quite indifferent groups — such as, for example, the methoxy- group — frequently has a marked influence on the colour. Thus dyestuffs derived from dianisidine /OCB., I wh:, are very much bluer than those from benzidine using the same second com- ponent. SUBSTANTIVE COTTON DYES. Up to the year 1885 it was always necessary to put the cotton fibre through a preparatory treatment before the artificial dyestuffs could be applied to it. In that year the " Actiengesellschaft fiir Anilinfabrikation " in Berlin introduced into commerce the dyestuff Congo, which had been discovered in the previous year by Bcittiger, and which possessed the property of affixing itself on to the cotton fibre without the aid of any mordant. Congo is made by the combination of tetrazobenzidine salts with sodium naphthionate, and therefore possesses the formula C,;H,N : N.C,„H,(NH:,)SO,Na i CjHiN : N.Ci,;H:5(NH;,)S03Na 1 The same difference is well illustrated by the three dyestuffs derived from tolidine in place of benzidine. 58 SYNTHETIC DYKSTCPFS. The property of this dyestuff of fixing itself directly on the cotton fibre is apparently due to the presence of the diplienyl residue in its molecule, since other dyestuft's derived in the same way from benzidine and its homologues possess this property. Benzidine is di-p-diamidodiphenyl of the formula and it appears tiiat one condition of tiie formation of substantive cotton dyestuffs is that the base from wiiiuh they are derived must bo a diamine, since the monoamido-dcrivatives of diplienyl do not yield azo-compounds substantive to cotton. Further, tlie two amido-groups must be in the para-position to the coupling bond, since it has been found that other amido-derivatives of diphenyl do not yield dyestuft's possessing this pro|ierty. To the presence, therefore, of the ^v-diamidodiphcnyl rest, in the molecule of Congo red, must be attributed its pro|)erty of affi.\ing itself to the cotton fibre. Homologues of benzidine containing the substituting group in the ortho- position to the amido-group also possess this property. Thus o-tolidine CH3 CH 1 r . dianisidine OCH3 OCH diphenetidine OCB, OCJH, and ethoxybenzidino OC3H. 1 are all valuable bases for the preparation of the azo-dyestutts substantive to cotton. Tiic same applies also to derivatives of benzidine containing halogen groups in the ortho-position to the amido-group. Thus odichlorobenzidine CI CI L, J NBL,<^ y-(^ ^NH., and y-dilironiobcn/.idine Br Br L J nh/ \-<^ \nh., yield azo-dyestull's substantive to cotton. If, however, substituting groups enter the benzidine molecule in the ortho- position to the coujjliiig bond, and therefore in the meta-position to the amido- group, the compounds formed do not yield azo-dyes substantive to cotton. Thus, ?)i-dichlorobenzidine THE AZO-DYESTTTFFS. 59 CI CI I <^_^NH, »i-diamidodiphenic acid COOH COOH J L NH.,<^ y <^ ^NHj benzidine-»(-disulphonic acid SOJH SO,H I L tolidiue disulphonic acid SO3H SO,H J l_ r 1 CH3 CH3 yield azo-corapounds which possess no affinity for the vegetable fibre. If, however, ring-formation takes place in the ortho-position to the coupling bond, then the bases yield substantive azo-dyestufts. Thus, diamidocarbazol < >-<_>^ NH, -<~> benzidine sulphone and diamidofluorene NH,^ y / NnH2 ^CH./ yield azo-dyestuti's substantive to cotton. It is not, however, only the derivatives of benzidine and its homologues that yield azo-dyestuffs substantive to cotton. There are a niuiiber of other bases which are also para-diamines, but in which the two benzene rings are not directly combined together. Thus the following bases yield important substantive cotton dyes : — diamidoazobenzene NH./ Nn : N<^ ^NH, ; ^)-phenylenediamine-azo-|)-xylidine CH3 I _^ NH.,<^\n ; N<^ ^NHs ; CH, 6o SYNTHETIC I)YKSTri''l'S. (li.iiMidocliplR'iiylaiiiine H c]i;iniidodii)lR'iiyluroii H H NH,/ ")-N— CO-N<^ \NH, ' diainidodiphenylthiourca H H NH2<^ \N— CS— N<( >NH., ' diamidostilbene diainidostilbenc disidplioiiic acid SOH SOH 4 " L" On the ullier hand : — /(-diaraidodiphenylniethane NHj/ \_CH._,— / NnHj ; and y/-diamidodibenzyl NH.,v^ \CH, . CH./ NnH„ do not yield azo-dyestuffs substantive to cotton. The sinijjlest ^'-diamine, viz., j)-plienylenediamine also gives substantive azo-dycstutts, whereas ?H-phenylenediamine docs not. Also certain diamines in the naphthalene series, as, for example, 1 : 5-dianiid(inaphthalenc, 1 : 4-diamidonaphthalciie NH, NH., ill III NH, NH., and 1 : -J-dianiidonaphthalenc-.'i : 7-ilisnlphouic acid NHe NH., yield azo-dyestuffs substantive to cotton. It therefore follows that although a lar^e nnnilicr nf dillorent bascH yield azo- dyestuffs which possess the property of directly dyeing the vegetal)le tilirc, yet they all have a very similar constitution. THE AZO-r>YKSTUFF.S. 6 I (1) They are all //diamines. (2) The amido-groups are in the para-position either to a bond joining two benzene rings, or to the point of juncture of a chain uniting two benzene rings. (3) This chain is unsaturated. (•4) In the case of derivatives of diphenyl, the ortho-position to the coupling bond must be free. If this position is occupied, then substantive cotton dyestufts are only formed when ring-formation takes place between the ortho-position in one benzene ring and that in the other. There is, however, a characteristic relationship between the colour of the disazo- compounds formed from diamines and their property of dyeing unmordanted cotton, by which it can always be ascertained whether any given base will yield substantive azo-dyestuU's. Those bases which yield these dyestufts give with naphthol sulphonic acids blue and violet compounds, and with naphthylamine sulphonic acids red dyestufts. The isomeric compounds which do not yield substantive cotton dyes give with naphthol sulphonic acids red, and with naphthylamine sulphonic acid orange- yellow dyestufFs. HISTORICAL. In 1864 Peter Griess {An/i., 1866, cx.xxvii. 60) showed that by the action of diazo-compounds upon amines, amidoazo-compounds were formed. The oxyazo-com pounds were first prepared in 1870 by Kekule and Hidegh (Ber., 1870, iii. 233) by the interaction of diazo-compounds with phenols. The first azo-dyestuff, amidoazobenzeue, had already been prepared by Griess in 18.59 {Ann., 1862, cxxi. 262) by the rearrangement of diazoamido- benzene, without, however, his realising the nature of the reaction. It was manufactured in 1863 by Simpson, Moule, and Nicholson under the name of Aniline yellow, and its constitution was determined three years later by Martins and Griess (Zeif.-'chi:, 1866, ii. 132). In 1865 Martins discovered Phenylene brown (Bismarck brown) and intro- duced its manufacture in 1866. This dyestuff, which was identified by Caro and Griess (Zeitschr., 1867, iii. 278) as triamidoazobenzene, still finds considerable application in the dyeing industry. Chrysoidine (diamidoazobenzene) was discovered at the end of 1875 by Caro, and immediately afterwards (January 1876) by Witt {Bei:, 1877, x. 654), and was technically prepared in 1876 by Williams, Thomas, and Dower of Brentford. Shortly afterwards Roussin prepared the first azo-dyestuffs from the naph- thols, which were introduced into commerce in the spring of 1877 by Poirrier under the names of Orange 1. and Orange II. In 1876 Griess prepared a number of azo-dyestuffs by the interaction of /j-diazobenzene sulphonic acid on various bases, which, in the same year, were independently prepared by Witt, and later named the Tropaolines. In 1877 Griess patented a large number of azo-dyestuffs in England, amongst others being a vellow dvest\iff prepared from diazodinitrophenol and phenol, and which were manufactured by Joseph Storey, of Lancaster, under the name of Lancaster yellow. The same patent includes the first red azo-dyestuff prepared by the inter- action of diazophenol sulphonic acid and /i-naphthol. In 1878 the firm of INIeister Lucius and Briining, of Hochstam-Main, patented the dyestuffs known as Pouceaux and Bordeaux, this being the first instance of the use of the disulphouic acids of the naphthols. 62 SYNTHETIC DYESTUFFS. The first (secondary) disazo-dyestuff was the Biebrich scarlet, prepared in 1879 by Xietzki (/J--;-., 1880, xiii. 800, 1838); and the first (primary) disazo-dye- stuff was the Eesorcin brown discovered by Wallach in 1881 (D.l'. 18,861). In 1884 Paul Hiittiger took out a patent (D.l'. 28,753) for the preparation of the first substantive cotton dye — Congo red — jirepared liy the interaction of tetrazobenzidine and sodium uaphthionate, a discovery which gave a consider- able impetus to the azodyestuff industry, and caused the preparation of a vast number of other dyestufts of similar constitution. The first satisfactory black azo-dyestuff was >i'aphthol black, discovered in 1885 by Hotliuann and Weinberg (D.P. 39,029, 3/7 85). In 1887 Green found that Priniulinc, previously discovered by him, ](ossessed the property of dyeing cotton direct, and that such dyeings could be diazotised on the fibre and developed with various second components, yielding dill'ereut colours. This discovery gave rise to the preparation of many azo-compounds contain- ing free amido-groups, which could be diazotised and developed in the same way on the fibre, yielding colours particularly fast to light and washing. The year 1889 marked the discovery by tians of the first direct cotton black (Diamine black RO), and this was followed by the many varieties of Columbia black (A). In 1891 Hotfniann and Daimler prepared the first direct-dyeing green colour (Diamine green). In recent jears considerable advance has been made in the production of insoluble azo compounds directly on the fibre. Thus Nitrauiliue red, prepared by treating cotton impregnated with /S-naph- thol with a solution of diazo-/)-nitraniliue, is a dyestuff of very considerable importance. Owing to the great ease with which the azo-colouring matters can be applied to the fibre, the question of their fastness to washing, light, etc., was perhaps formerly, to some extent, overlooked. The continued use, however, of the faster mordant dj-estuflfs. Aniline black and even some of the natural dyestuffs, has stimulated research in the field of azo-dyes, and since about 1894 many new compounds have been pressed into the service of producing dyestutl's particularly distinguislied by their powers of with- standing light and the usual reagents. DIVISION OF THE AZO-DYESTUFFS. The azodyestufTs can be divided into four chief classes: — (1) Those containing one azo-group — nionoazo-dyestufTs. (2) Those containing two azo-grouii.s -disazo-dyestutl's. (3) Those containing three azo-groups — trisazo-dyestuffs. (4) These containing four azo-groups — tetrakisazo-dyestuffs. Each chief division can be subdivided into other divisions, thus: — (1) (a) Amidoazo-compounds. (/<) Oxj-azo-compounds. (2) (a) Primary disazo-compounds. (i) Secondary disazo-compounds. (c) Dyestutfs from tetrazo-salts with two similar or two dilferent molecules of an amine or phenol. (3) Are not subdivided. (4) Are usually produced as such on the fibre by development. THE AZO-liYESTUFFS. 63 A short description of each subdivision will be foinid in the following pages, together with one or two examples from each ; for a more detailed description of the azo-compounds the reader is referred to larger works on the subject, e.g. : — Schultz, Cliemie -nitro- benzene a7j-iiitrobeuzene diazonium chloride), which is then available for the use of the dyer to prepare /)-nitraniline red (Nitrosamine red). The nitrosamine jjaste admixed with /3-naphthol can also be printed on the fibre, when, on passing the printed material through dilute acid, the dye will be developed. Dyestuffs similar in composition to j)-nitraniline red can also be prepared by the diazonaphthylamines and from diauisidine. The soluble o.xyazo-compounds are the sodium salts of the various sulphonic acids, and are jirepared by combining sulpho-acids of phenol and naphthols witli diazo-salts. The Ponrcaux are compounds prepared by the interaction of various diazo- salts with the naphthol sulphonic acids. Two typical instances are : — Ponceau 401". [A] /0H3 CeH^N : NC„,H ,< SO.,Na prepared from diazol)enzene chloride and /j-naphthol monosulphonic acid (SchiifFer's acid), and Cnjstal Ponceau [B], crystal I'onceau 6B [C] /OH ((3) C,hH-.N : NC,„H/ \(SO;,Na),, prepared from dia/.dnaplithalcno chloride and /3-naphlliol disulphonie acid G. They arc acid dyestufi's and are well adapted for tiie dyeing of wool. Fa-^/ n-il A [1!] is an instance of a dyestufY of this group which contains two naphthalene rings ; it is ,SO.,Na C,„H,/ ^N : N ~ C,„H,;OH and is prepared from dia/.o-naphthionic acid and /i-naplithdl. There arc also certain dyestull's belonging to this series which arc made by the use of salicylic acid OH (1) CaH/ ^COOH (2) as second cumpduent. THE AZO-DYESTUFFS. 65 Such are : — Alizarine yelloio GG [M] CfiHj NO., ^N : N.C6H,< ^COOH prepared from )/j-iiitraniline and salicylic acid, and Diamond yelloio G [By] ,COOH CsH/ on ^COOH prepared from the diazo-salt of ?K-amidobenzoio acid and salicylic acid. Owing to the presence of the OH and COOH groups in the ortho-position in the salicylic acid residue, these compounds are mordant dyestufts, and find considerable application as such in the textile industry. In this respect, also, the azo-dyestufFs derived from chromotropic acid are interesting. This acid is 1 : 8-dioxyuaphthalene-3 : 6-disu!phonic acid .'SO^H and its sodium salt gives, on combination with diazo-salts, the dyestufFs known as the Chromotropes. Here, again, the pen-position of the hydroxyl groups in the chromotropic acid causes the azo-dyestuffs derived from it to form lakes with metallic salts. They may be applied as follows : — Wool is dyed red in an acid bath containing a Chromotrope, and, on subsequent treatment with potassium bichromate solution, becomes dark blue to black. The dyeings thus produced are exceptionally fast ; owing, however, to their cost of production the Chromotropes are not used to any considerable extent technically. Other dyestuffs of this gi Sudan G [A] Sudan I. [A] Ponceau 2G [A] . Grange G [A] Chromotrope 2R [M] Alizarine yellow (JG [M] Chromotrope 2B [M] . Alizarine yellow K [By] . Victoria violet 4BiS [M] . Chromotrope 615 [M] Cochenille scarlet 2K [Scii] Orange GT [By] . Azofuchsine B [By] Sudan II. [A] Azococcine 211 [.A] Wool scarlet R [Sch] . Palatine scarlet [P>] roup are : — Aniline -I- resorciiiol. Aniline + yS-naphthol. Aniline -t- /?-naphthol disiilphonic acid E. Aniline -f/3-naphthol disulphonic acid G. Aniline + chromotropic acid. 7/«-nitraniline -f- salicylic acid, p-nitraniline + chromotropic acid, jj-nitraniline -t- salicylic acid. Alkaline reduction of Chromotrope 2B. //-amidoacetanilide -t- chromotropic acid. Toluidine + a-naphthol sulphonic acid C. Toluidine -I- /J-naphthol sulphonic acid S. Toluidine -I- dioxynaphthalene sulphonic acid S. Xylidine + /3-naphthol. Xylidine -H a-naphthol sulphonic acid NW. Xylidine -I- a-naphthol disulphonic acid Sch. »(-xylidine H- a-naphthol disulphonic acid EG. 5 r 66 SYNTHETIC DYKSTUFFS. Xylidine + ^-naphthol sulphonic acid S. Xylidino + /3-iiaphthol disulphonic acid R. i/^-cumidine + ZJ-naphthol disulphonic acid R. a-naphthylamiue + a-naphthol. a-naphthylamine + a-naphthol disiili)honic acid RG. a-napliUiylamine + ^-naphthol sulphonic acid S. a-naphthjlamine + ^-naphthol disulphonic acid R. a-uaphthylaniinu + chromotropic acid, o-anisidiue + a-naphthol sulphonic acid NW. o-anisidino + a-naphthol disulphonic acid Sch. Tetrazobenzidine -f 1 mol. salicylic acid, boiled.' Dehydro-thio- ?«-xylidine + a-uaphthol-t-disul- phonio acid. Sulphanilic acid + resorcinol. Sulphanilic acid + a-naphthol. Sulphanilic acid -f /3-naphthol. Sulphanilic acid -f dioxynaphthalene sulphonic acid S. Naphthionic acid -i- a-naphthol. Naphthionicacid 4- a-naphthol sulphonicacid NW. Naphthionic acid -f/3-naphthol sulphonic acid S. Naphthionic acid -l-/?-naphtholdisulphonio acid R. Naphthionicacid +/8-naphthol disulphonic acidCi. Naphthionic acid -t- /i-naphthol trisulphonic acid. Naphthionic acid + chromotropic acid. Naphthionic acid -f /J-naphthol. /j-naphthylamine sulphonicacid Br-f/i-naphthol. /J-naphthylamine monosulphonic acid Rr + salicylic acid. y8-naphthylaniine disulphonic acid G -f- salicylic acid. Primuline + salicylic acid, o-amidobenzoic acid -t- salicylic acid. 7;j-aniidobenzoic acid -(-salicylic acid. _^;-amidoacctanilide -I- a-naphthol -3 : 6-disulphoiiic acid. Safranine + /8-naphthol. 1 : 8-amidonaphthol-3 : 6 disulphonic acid H -i- 1 : 5-amidonaphth()l. Primuline -I- a-naphthol sulphonic acid NW. DisazO-dyestuffs. — (l) Pn'man/ — These are the azocompounds which are formed by the successive action of two similar or different diazo-salts — obtained by the diazotisation of a monamine — on an amino or phenol, whereby the two diazo groups enter on different carbon atoms of the phenol or amine used. The first example of this class was Aniline disazophenol CuH^N : N. NCeHpH CeHjN : N/ prepared in 1864 by Griess, by the action of potassium carbonate on diazobenzene nitrate, and called by him oxytetrabenzene or phenolbidiazobenzene {Ah7i., 1806, cxxxvii. 84). ' Tlie second diazo-groiip is tluis ooiivortcd into the OH group. ISrilliant orange R [M] Ponceau 2R [A] . Ponceau 311 [A] . Sudan brown [A] . Palatine red [H] . Fast red P.T [By] . Fast red B [By] . Chromotrope lOB [M] Azoeosine [By] Azocochenille [By] Diamond flavine [By] Erika B [A] . Chrysoine [B] Orange I. [M] Orange 11. [B] . Azofuchsine G [By] Naphthylamine brown [1!" Azorubine [Lev] . Fast red [A] Fast red D [B] . New coccine [B] . Ponceau 6R [M] . Chromotrope SB [M] . Fast red A [A] . Double brilliant scarlet (J [A] Chrome yellow D [By] . Crumpsall yellow [Lev] . Cotton yellow R [Bl Diamond yellow R [By] Diamond yellow G [By] Sorbine red [Kj Lanafuchsine [C] . Indoine blue R [B] Lanacyl blue BB [C] . Rosoplicnine SG [CI Co] THE AZO DYESTUFFS. 67 The followiug two dyestuffs are typical members of this serisi?, and are of considerable importance : — Resorcin brown OH CH3 /\N: n/\ l^OH '\/'cH3 N : N^ \sO3Na or H;-xylidine ^ ^resorcin ol, sulphanilic acid^ is prepared by the action of diazoxylene chloride in alkaline solution on Eesorcin yellow /^ N : N / ^SOjNa Naphthol blue black [C] OH NH., CiHjN : N| \^\N : NCsHjNOj SO,Na\ /'x^/'SOjNa or p-nitraniline^ yamidonaphthol disulphonic acid H. aniline^ Other dyestuffs of this group are : — Terracotta F [G] . Primuline ^ ^y;i-phenylenediamine. Naphthionic acid^ Cotton orange R [B] Primuline ^ /?;i-pheuylenediamine disulphonic acid. Metanilic acid'^ Fast brown [By] . Naphthionic acid. ^resorcinol. Naphthionic acid^ Fast brown G [t. M] Sulphanilic acid. ^a-naphthol. Sulphanilic acid-^ Wool black 6B [A] . Sulphanilic acid (in. acid solution) ^1:8- amidonaphthol - 4 - sulphonic a-naphthylamine (in-''^ acid, alkaline solution) (2) Secondary. — These are compounds made by the combination of diazotised amidoazo-dyestuflfs with amines and phenols. The series contains many important dyestuffs, which find their chief applica- tion in the dyeing of wool. 68 SYNTHETIC DYESTUFFS. Tlie following are typical examples : — Bieliricli scarlet. — This dyestuir is prepared from the diazo-corapoiind of F;ist yellow combined with /3-naphtiiol. It therefore consists of two compounds, one made from the monosulphonic acid of Aniline yellow, and having the formula ,SO;,Na *\n : NCoH.N : N. CioH^OH ' and another made from the disulphonic acid and having the composition .SOoNa CeH,< ^N : N.aH, /SO.Na The disulphonic acid, however, usually predominates. y.i/ihthol iiknk [C] contains three naphthalene rings CioH- (SO,Na),, ^N : N - C,(,H,; - N : N - C.Mi that is SOjNa ■pra. XSOjNa), SOjNa'-s^', SONa It dyes wool black from an acid bath. Other dyestuft's of this seri Sudan III. . Cloth red G [By] Brilliant crocein [.M] I'unceau 511 [.M] . Cloth red 3B [By] Cloth red B [By Crocein 3B [Sch Cloth red B [0] . Bonlcaux BX [By] Union fast claret [Lev] Cloth scarlet G [K] Ponceau -iRB [A] Crocein scarlet extra [K Fast Ponceau 2B [B] . Crocein scarlet 8B [By] Fast violet (reddish) [By] Anthracite black B [C] Amidoazobenzene + /J-uaphthol. Amidoazobenzene + a-naphthol siilphonic .acid NW. Amidoazobenzene + /3-naplithol disulphonic acid G. Amidoazobenzene + /?-naphthol trisulphonic acid. Amidoazotoluene + /i- naphthylamine -S - monosul- phonic acid. Amidoazotoluene + a-u iphthol sulphonic acid N W. Amidoazotoluene + a-uaphthol disulphonic acid Sch. .Vmidoazotoluene + y8-naphthol disulphonic acid II. Amidoazoxylene + y3-naphthol sulphonic acid S. Aniidoazoxylene + /^-naphtholdisulpiionic acid K. Amidoazobenzene sulphonic acid -l-/3-naphthol. Amidoazobenzene sulphonic acid + /8-naphthol sulphonic .acid (2:8). Amidoazobenzene disulphonic acid + /3-naphthol sulphonic acid B. Amidoazobenzene disulphonic acid + /:J-naphthol disulphonic acid R. Amidoazotoluene sulphonic acid + /i-naphthol sulphonic acid B. Sulphanilicacid-azo-a-naphthylaraine + /3-naphthol sulphonic acid S. a-uaphthylamine disulphonic acid-azo-a-naphthy- lamine + diphenyl-m-pheuylenediamine. THE AZO-OYESTUFFS. 69 Naphthylamine black D [C] a-naphthylamine disulphonic acid-azo-a-naphthyl amine + a-naphthylamine. Naphthol black 6B [C] . a-naphthylamine disulphonic acid-azo-a-naphthyl- amine -1- /iJ-naphthol disulphonic acid R. Diamond green [By] . . Amidosalicylic acid-azo-a-naphthylamiue + dioxy- naphthalene monosulphouic acid S. Diamond black [By] . • Amidosalicylic acid - azo - a - naphthylamine + a- naphthol sulphonic acid NW. Diaminogen black [C] Acetyl-1 : 4-naphthylenediamine 6 or 7 sul- (for cotton) phonic acid - azo - a - naphthylamine -f amido- naphthol sulphonic acid y. (The end pro- duct saponified.) Naphthyl blue black N [C] . a-naphthylamine disulphonic acid (4:7)-azo- a-naphthylamine ethyl ether -I- a-naphthyl- amine. Janus red [M] . . . »i-amidophenyltriniethylammonium-azo-)»- tolu- idine + ^-naphthol. DyeStuffs from tetraZO-saltS are prepared by combining a tetrazo- salt obtained from a primary diamine, with two similar or different amines or phenols. The most important members of this class are those which are derived from benzidine and its homologues, which, as previously mentioned, possess the property of directly dyeing the cotton fibre. The formation of the disazo-dyestnff is brought about in the usual way. The diamine is treated with nitrous acid and converted into the tetrazo-salt, a process which in the case of benzidine and its homologues proceeds very smoothly. The only difference, then, between the formation of the azo-compound and the disazo-compound is that in the case of the latter two molecules of the amine or phenol used as second component have to be employed. The formation of the disazo-dyestuffs takes place in two distinct stages. In the first place one molecule of the second component combines with the tetrazo- salt, forming a well-defined intermediate product which still contains a free diazo-group. These intermediate products may be in most cases isolated, and are well- characterised, often crystalline, compounds. By boiling with water the diazo-group is replaced by hydroxyl, and dyestuffs are formed which are, however, of little technical value.' If the intermediate product is further combined with another molecule of the same amine or phenol, the simple benzidine dyestuffs are produced, and if a molecule of some other amine or phenol is employed, the mixed bunzidine colours are formed. Thus : — Tetrazobenzidine chloride aHjN.Cl I C.H,N.,C1 combines Immediately with 1 mol. of sodium naphthionate in acid solution to form the intermediate compound /NH, (1) CsH.NiN-C.oH/ i ^SO^H (4) C6H4N.,C1. ' With the exception, however, of Diamond flavine. 70 SYXTHKTIC DYESTUFFS. This diazo-salt, on combination with a further molecule of sodium naphthiouate, vields the acid of which t'ougo red is the sodium salt CeH,N:N.C,<^< CeH5N:N.CK;H, /NHj (1) NH; (1) SOjNa (4) The entrance of the second molecule of the second component takes place, however, slowly, and in some cases it is necessary to allow two to three days to elapse before combination is complete. If the above intermediate compound is combined (in alkaline solution) with, for example, 1 niol. of Neville and Winther's acid (1 : 4-naphthol sulphonic acid), a mixed benzidine dyestuff — Conyo Corinth — is produced C„H^N ; N.C,„H, I CsH,N:N.C,,H, nh:. (1) SO.,Na (4) OH (1) SOjNa (4) A variety of bases used in the preparation of tlie substantive cotton dyes have been already mentioned on pp. 58 ef seq., and it is easy to understand that these bases, both in mixed and simple combination with the large number of naphthol and naphthylamiue sul[)honic acids available for the purpose, render the number of the azo-dyestuffs substantive to cotton, which have been prepared and which are in daily use, very considerable indeed. The following list gives the more important disazo-dyestuffs derived from the /)-diamines : — /Salicvlic acid. Cotton vellow (! Brilliant Congo Diamine fast red F Diamine black RO Chrysaminc O Diamidodiphenylnrea /' Benzidine Benzidine Benzidine- Benzidine salicylic acid. 78-naphthylamine disulphonic acid R. /3-naphthylamine niouosuljihonic acid Br. •salicylic acid. ^-amidonaphthol sulphonic acid (in acid olution). /■y-amidonaphthol sulphonic acid. ^-amidonaphthol sulphonic acid. /Salicylic acid. \ Benzopurpurine IB . Tolidine- \, salicylic acid. ^naphthionic acid. uaphthionic acid. Benzopurpurine B Rosazurine B Azo blue Benzoazurine G Benzo fast pink 2BL [By] Diamine brown M [C] . Benzidine< Pyramine orange 3G [B] . Benzidine/ Benzo violet R [By] . Benzidine<^ Diamine black BH [C] . Benzidine<^ Benzopurpurine 10 B [By] Dianisidine THE AZO-DYESTUFFS. 7^ //3-naphthylamine sulphonic acid Br. ^/iJ-naphthylamine sulphonic acid Br. /ethyl-;8-naphthylamine sulphonic acid F. "^ethyl-ZJ-naphthylamine sulphonic acid V. ytt-naphthol sulphonic acid NW. ^a-naphthol sulphonic acid NW. .a-naphthol sulphonic acid NW. Dianisidine/ ^a-na]jhthol sulphonic acid NW. y2 mols. amidonaphthol Di-p-amidodiphenylurea/ sulphonic acid y (in disulphonic acid ^ neutral or acid solu- tion). Tolidine< Tolidiue< Tolidine< Chicago blue 6B [A] Carbazol yellow [B] . Diamine sky blue Naphthylene red Dianisidine: Diamidocarbazol Dianisidine /Salicylic acid. ^amidonaphthol sulphonic acid y (alka- line solution). /nitro-?rt-phenylenediamiue. ^??j-phenylenediamiue disulphonic acid. /Neville and Wiuther's acid. '^a-naphthol-3 : 6-disuIphonic acid. /amidonaphthol sulphonic acid y. ^amidonaphthol disulphonic acid H. naphthionic acid. naphthionic acid. 2 mols. of 1 : 8-amidonaphthol-2 : 4- disulphonic acid, salicylic acid ^salicylic acid. amidonaphthol disulphonic acid H. ■amidonaphthol disulphonic acid H. naphthionic acid. 1:5- diamidonaphthalene< ^naphthi acid. 72 SYNTHETIC DYEtSTUFFS. /^-naplitliylaiuine. Hessian purple X . Diamidostilbeiie disulphonic acid/ V^-naphthylauiine. yplicnol. Chrysojihenine . . Diamidostilbene disulplioiiic acid<^ ^phenetol. Sulphoiiaziirine yphei)yl-/3-naphthylamiiie. Benzidincsulphone disulplionic acid^ ^plienyl-/3-naphthylamine. ,a-iiaplitliol sulphonic acid NW. St Denis red . . Diamidoazoxytoluene<^ ^a-naplithol sulphonic acid NW. Bismarck bmcn is derived from Hz-phenyleuediamine on treatment with nitrous acid. It is one of the oldest azo-dyestulFs, having been discovered in 1864 by Martiu.s, and prepared technically by Roberts, Dale, & Co. in 1866. It is formed by the combination of 2 mols. of 7;i-phenylenediamine with tetrazo-OT-phenylenediamine, and therefore has the fonuida (3) /NH., (I) / ^NH., (3) \(1) /NH., (1) ^NH., (3) It is a basic dyestuff, dyeing wool a red-lirown shade. It has no affinity for the eotton fibre, and can only be affixed to it with the aid of tannin. Trisazo-dyestuffs. — These dycstuffs can be prepared by a variety of methoils, one of wliich consists in so arranging that one of the second components in a benzidine colour contains a diazotisable amido-group. Thus : — Benzo (jreij [By] is /Salicylic acid. benzidine((' ^a-naphthylaminc + a-naphtliol sulphonic acid NW. Diamine bronze G [C] is , salicylic acid, benzidine^ \amidonapiithul sulphonic acid H + 7?^-phenylenedian■line. Benzo indigo blue [By] is /dioxynaphthalcne sulphonic acid S. tolidino/^ \i-naplithylaniine + dinxynaphtlialene Rul])honic acid S. Columbia blarl; K [A] is <" ^ ^amidonapiitliiil disul|ihonic arid y + »(-toluylencdiamine. ym-toluylcnediamine. tolidine< THE AZO-DYESTUFFS. 73 Another method for the preparation of these dyestuffs consists in allowing a diazo-salt to react on one of the components of a benzidine dyestuff. Thus : — Diamine green B [C] is ^salicylic acid. benzidine<^ ^amidonaphthol disulphonic acid H. p-nitraniline^ Congo hrown G [A] is /Salicylic acid, benzidine/ ^resorcinol. sulphanilic acid^ Columbia green [A] is /Salicylic acid, benzidinec^ ^amidonaphthol sulphonic acid 1:8:4. sulphanilic acid^ Other dyestuffs of this group are : — Benzo olive [By] /Salicylic acid. Benzidine(f ^a-naphthylamine + amidonaphthol disulphonic acid H. Benzo black blue R [By] /tt-naphthol sulphonic acid NW. Tolidine/ ^a-naphthylamine + a-naphthol sulphonic acid NW. Benzo black blue G [By] ,a. - naphthylamine + a - naphthol sul- Benzidine disulphonic aoid<^ phonic acid NW. ^a-naphthol sulphonic acid NW. Benzo black blue 5G [By] /a-naphthylamine + dioxynaphtlialene ISenzidine disulphonic acid<^ sulphonic acid S. Mioxynaphthalene sulphonic acid S. Congo brown R [A] a-naphthylamine sulphonic acid L\ ~^resorcinol. Tolidine/ ^amidophenol sulphonic acid III. Alizarine yellow FB [DH] . . Magenta + salicylic acid. Columbia black FB [A] /a-naphthylamine sulphonic acid (Cleve). ;>phenylenediamine<^ ^amidonaphthol sulphonic acid y + OT-pheny- lene diamine. 74 SYNTHETIC DYKSTIKKS. Tetrakisazo-dyestufTs. — For the most part, the dj-estufTs of this group are produced directly on the fibre by the diazotisation and development of material dyed with some substantive cotton dye contaiuing two diazotisable amido-groups. The colours produced are known as " Ingrain colour," and the method was first introduced by Green, who applied it to Primuline (see p. 153). There are, however, a few dyestuffs of this group which are introduced into commerce in the finished state. Thej' may be divided into two classes : — (1) Those from two monaraiues and one diamine, of which two typical e.\:imples are — Denzo brown G [By] Sulphanilic acid^ ^»i-phenyleiiediamine JH-phenyienediamine/^ ^?«-phenylenediamine Sulphanilic acid''^ prepared from Bismarck brown by treatment with two molecules of diazo- sulphanilic acid ; and Hessian brown BE [L] Sulphanilic acid^ ^resorcinol. Benzidine<^ ^resorcinol. Sulphanilic acid^ (2) Those from two diamines, of which two examples are — Mekong yellow G [DH] ySalicylic acid. Eenzidine<^ y^dioxydiphenylmethane. Benzidine/^ ^salicylic acid. and Azo orange R [DH] yUaphthionic acid. Tolidine<^ ydioxydiphenylmethane. Tolidine/ ^naphthionic acid. Both these dyestuffs are prepared by the action of two molecules of the diazo intermediate product upon one molecule of dioxydipheuylmethane. Other dyestufTs of this group are : — Benzo brown B [By] . . 2 mols. naphthionic acid + 1 niol. Bismarck brown. Direct brown J [J] . . 2 mols. »(-ainidobenzoic acid + 1 mol. Bismarck brown. THE AZO-DYESTUFFS. 75 Toluylene brown [By] Naphthionic acidx Toluylenediamine sulphonic acid< Hessian brown MM [L] Naphthionic acid^ SulphauiHc acidy Tolidine^ >?»-phenylenediamine. )//f-phenylenediamine. >resorcinol. >resorcinol. Mekong j-ellow E [DH] Sulphanilic acid^ ^naphthionic acid. Tolidine< Tolidiue< >dioxydiphenylmethane. Miaphthionic acid. CHAl'TKi; XII. HYDRAZONES. TuE close relationship between the hydrazones and the azo-compounds has already been commented >i])on. There is, however, one dyestiill', 'J'arfrazine, which from its method of prepara- tion should belong to the hydrazones, but which later researches has shown to possess a different constitution. Tartrazine was discovered by Zieglcr in 1884 (Ber., 1887, xx. 834), who prepared it by the action of phenylhydrazine sulphonic acid upon sodium dioxytartrate. The formula of dioxytartarie acid in its hydrated condition is evidently COOH.C(OH)o.C(OH)..COOH ; but, like similar compounds containing two hydroxyl groups on the same carbon atom, it reacts as the diketone COOH.CO.CO.COOH. Ziegler therefore considered the formation of Tartrazine to take place in the following manner : — COOH COOH I I CO H N NH.C,H,SO Na C : N NH.C,H,SO Na \ >■ ~ -> I - :;h.,o CO KN NH.C,3H,S0Na C : N NaCH^SO^Na I " " I COOH COOH Tartrazine. Jlore recent researches bj' Anschiitz {Ann., ccxciv. 219) have shown, however, that this substance is only an intermediate product in the formation of Tartrazine, and that the dycstutl' is formed by the elimination of one molecule of water from the above dihydrazono. Tartrazine is therefore proliably a pyrazolone derivative, its formation being represented by the scheme COONa COONa I ' \ C:N.N Hi.CjH^SOsNa C :N I : i I I S03NaC6H,.NH.N:C -SO Na.C,H,.NH.N : C CO OH: CO. NC,JI,.SONa ..i Tartrazine. Although many dyestuflTs belonging to this groiip have been prepared and patented, Tartrazine is the only one of any commercial importance. It is a handsome yellow wool dye, extremely fast to light, in which respect few other dyestufls are superior to it. 76 CHAPTER XIII. AURAMINE. H. Caro and A. Kern in 1883 (E.T. 5512**-') prepared a dyestuft" by fusing tetratnethyldiamidobenzophenone with ammonium chloride and zinc chloride at 150-160°, which was introduced by the Badische Aniline and Soda Fabrik under the name of Auramine. Its method of preparation can be represented by the following equation : — /CsH,N(CH3), / C0< + NH, -^ C^=NH + H.,0 tetramethyldiamidobenzoplienone. Auramine base. At the present day, however, this dyestuff is prepared by a method suggested by Sandmeyer in 1889 (E.P. 12,549^9, and 16,666'^°), which consists in heating tetramethyldiamidodiplienylniethane with sulphur, ammonium chloride, and common salt in a current of ammonia gas. In this reaction tlie thioketone ^.CeH,N(CH3)„ \c,HjN(CH,,)., is formed as an intermediate product. Auramine is a basic wool dyestuff or tannin cotton dye, and is most frequently met with as its hydrochloride. It is exceptionally fast to light, but, unfortu- nately, is readily hydrolysed by boiling water. Hence in its use care must be taken not to allow the dye-bath to exceed a temperature of 60-70° C. It is in its properties closely allied to the compounds of the triphenyl- methane series to be mentioned later. Thus, on reduction, it is converted into a " leiico " or colourless compound, which is retransformed into the dyestuff on oxidation. The constitution of the Auramine base given above is that suggested by Graebe. Stock {J. })val\ Chem., xlvii. 401, 1893), however, considers that the quinone structure represented by the formula * /C6H,N(CH3)2 \c,;Hj = N(CH3)2Cl best represents the constitution of Auramine hj'drochloride. 78 SYNTHETIC DYESTUFFS. He bases his opinion upon the presence of an imino - group in phenyl- auriunine iiydrochloride C^NH.C,H5 ^C6Hj = N(CH.,).,Cl Tliis formula represents Auramine hydrochloride as a triphenylmethane derivative, in which one of the phenyl groups has been replaced by an amido- group. Auramine G [B] is prepared by heating sym-dimethyldiamido-di-o-tolyl- methane with sulphur in a current of ammonia gas. Its constitution is represented by the formula CH. J " ,/ NHCH; C^ NH., > = NHCH, CI CHAPTER XIV. TRIPHENYLMETHANE DYESTUFFS. The hydrocarbon triphenylmethaue C,jH-, H \CeH5 is the basis of a large number of important dyestufis, which can all be considered as anhydro-derivatives of triphenylcarbinol. These dyestuffs are the salts of the bases or acids formed by the entrance of amido- or hydroxyl groups iuto the molecule of triphenylcarbinol, which salt- formation always takes place with elimination of water. One, two, or three amido- or hydroxyl groups may enter, but only the di- and tri-derivatives are of importance as dyestuffs. Furthermore, it is necessary that these groups should enter into different benzene rings, and in the ^ar«-position to the methane carbon atom. The triphenyl methane dyestuffs will therefore be considered under the following heads : — («) Those containing two amido-groups — The Malachite green series. (b) Those containing three amido-groups — The Rosaniline series. (c) Those containing three hydroxyl groups — The Rosolic acid series. (a) The Malachite Green Series. The older members of this group are green, and it was not until the year 1888 that blue members — the Patent blues — were prepared. Malachite green usually appears in commerce as the zinc chloride double salt of the formula / + 2ZnCL, + HjO ■^C,;H4 = N(CH..).,Cl/ and is prepared by a method fully described on p. 242. It is one of the oldest of the artificial colouring matters, and was discovered by 0. Fischer in 1877 (Ber., 1877, x. 1624), who prepared it by the method used for its commercial production at the present day. Brilliant gree?i is the corresponding tetraethyl derivative of the formula (sulphate) \C6H4 = N(C,H,).,SOjH Its method of preparation is analogous to that of Malachite green. 8o SYNTHKTIC DVESTUFFS. Victoria green 3B [Bv] /CoH,Cl, O^C,H,N(CH,), \o^, = N(CH3).,Cl is interesting as showing the influence on the colour of a compound of this series by tlie entrance of chlorine atoms into the uiisubstituted lienzene ring. It is prepared from dichlorbenzaldehyde (CHO : CI : CI -> 1:2:5) and dimethyl- aniline, with subsequent oxidation of the leuco-base formed. The shade of green of this dj-estuff is very much bluer than that of Malachite ttreen. Sulphonic acids of the Malachite green series.— The production of siilphonic acids from members of the tri]ihenylmetluine series will be more fully discussed under the head of the suljihonic acids derived from dyestuffs of the Uosaniline series, since these arc of more importance than those derived by the sulphonation of dyestufTs of the Malachite green series. Helvetia green, which is the sodium salt of the sulphonic acid prepared by the direct sulphonation of Malachite green, is no longer manufactured, and has been replaced by Arid green (OG) [By], or Light green (SF yellowish) [B], prepared by sul- phonalint,' the condensation product of benzaldehj'de with benzylethylaniline, and therefore (as sodium salt) possessing the constitution /C6H,S0,Na Cc^ C«Hj( C.,H,)CH:,C. H,SO Na 1 OH ^C„H,{C.>H,)CH._,C,.H,S03Na Another interesting dyestuff of this series is : — F(ut gn-en [By], which is prepared by first condensing 77!-nitrobcnzal- dehyde with dimethylaniline ; then reducing the nitro-group to the amido-group ; and finally, after converting the amido compound into its dibenzyl derivative, producing the disulphonic acid by sulphonation. Its formula (sodium salt) is therefore (1) (1) /CcH.NlCH,)., ' (4) OH C C,HjN(CH,\, \C,H,N CH.,C,H,SO,Na).., Patent blues.-— In 1888 it was discovered by the lirm of Meister Lucius & Briining, of lloclist (Herniiaiin ; D.P. 4G,38-t, etc.), that by the condensation of ?/(-o.\ybinzaldehyde with symmetrically or unsymmetrically alkylated derivatives of aniline, leuco-compouiids were produced, which could be converted into valuable greenish-blue dycstufts on sulphonation and subsequent oxidation. The same compounds can also be produced by starting with the corresponding ??i-nitro- or ?»-amido-derivativo of benzaldehyde, and converting the nitro- or amido-group into hj-droxyl by the usual methods, after condensation with the dialkj'lated aniline. TRIPHENYLMETtrAXE DYESTUFFS. 01 A typical member of the series is : — Patent blue V, which, according to Erdmann (Ant/., 1897, ccxciv. 376), possesses the constitution /C.H.NCC.JH.)., q/ (Cai)03sV\so,, 1^ It is prepared by either of the following methods : — (1) Condensation of 1 mol. ??i-nitrobenzaldehyde with 2 mols. of diethyl- aniline. Conversion of the ;«-amidotetraethyldiamidotriphenylmethane thus pro- duced into the corresponding hydrosy-derivative by means of nitrous acid. Sulphonatiou. Conversion into the calcium (or magnesium) salt. Oxidation. (2) Condensation of )/;-oxybenzaldehyde with diethylaniline. Sulphonatiou of the 7«-oxytetraethyldiamidotriphenylmethane thus formed. Conversion into the calcium salt. Oxidation. It is an important wool dye, particularly fast to light and alkali. Other dyestuffs of this group are : — Gyanol (Weinberg, 1891) or Acid blue 6G, prepared by using monoethyl- o-toluidine instead of diethylaniline in either of the above methods for preparing Patent blue V. Patent hlite A, prepared by using ethylbenzylaniline instead of diethylaniline. Azn green belongs both to the azo- and triphenylmethane dyestuffs, and is prepared by diazotising »i-amidotetramethyldiamidotriphenylmethane ,-. C,iH,N(CH3), \-/ I \CeH,N(CH3), NHl, H and combining the diazo-compound thus formed with salicylic acid. This leuco- base is finally oxidised. It is an important green mordant dj-estuff. Other dyestuffs belonging to the Malachite green series are ; — Glacier blue [J] Guinea ijreen B [A] /C6H3(CH3)NH.CH3 ^CjHjlCHs) = NHCH.Cl /CsHjN(C,H5)CH.AHjS03Na HO-C::^C6H5 \c6HjN(C,H5)CH,.,CoHjS03Na Cyauol extra [C] /CsHslCHJNH.CjHj HO-C(^ CfiHUjOHXSOjNa),. '\C6H3{CH.,)NHC,,H5 •arsenic iicid. L trobenzcne. 82 SYNTHETIC DYKSTl'KKs. (i) The Rosaniline Series. In 1859 Prof. Verguin, of Lj'ons, made the discovery that a red dyestiitf is formed when aniline is oxidised by tin chloride. This product he named Fuclisin, and introduced its commercial manufacture in conjunction with the firm of Kdnard Brothers, of Lyons. The production of this important dyestuft" led to the investigation of the action of other oxidising agents upon aniline, with the result that between 1859 and 1861 a large number of patents were taken out for the production of Fuchsin from aniline by the aid of various oxidising agents. Chief amongst these are : — Broomann .... mercuric chloride. Medlock . Nicholson . Gerard de Laire . Lauth Laurent . Castelhaus Coupler At the same time numerous chemists were engaij;ed elucidating the con- stitution of Fuchsin (MaL;enta),' and also its method of formation, amongst these being A. W. Hofmann, 0. and E. Fischer, Rosenstiehl, Dobner, Caro, Dale, Schorlemmer, and others. The first important scientific research on the subject was that published by A. W. Ilofmann in 1862 (/. pr. Cliem., 1862, Ixxxvii. 226), who found this substance to be the salt of a base named by him rosaniline, which, on reduction, was converted into a base — leucaniline — characterised by forming colourless salts with acids. The successful elucidation of the constitution of Magenta is due to Otto and Emil Fischer (Ber., 1880, xiii. 2204), who found that leucaniline is a primary triamine, which, on treatment with nitrous acid and boiling with absolute alcohol, is converted into triphenylmethane. They further found that this hydrocarbon, on treatment with fuming nitric acid, is converted into a trinitro-derivative, which is reducible to leucaniline. Thus :— /C0H5 /C„HjNO,, 0^-— C„H. + 3HN0 -> C^ aH.NO.. H ^CoHs H \c„H,NO.. (triphenylmethane). (trinitro-derivative). /CeHjNO,, /CcH^NH., Ce^-CoHjNO., reduction C-^ C.-H^NH, I \ I X H \CoHjNO., H ^CoH.NH., Also (leucaniline). /C,;H,NH, C,Hj I \ niul alcohol i ^ H \C„H^NH., H ^C„H5 ' .Magi'iita, the En,'lisli muiie for tliis (lyostulV, is used in tliis work. I''uclisiii is the (lermaii iiamo. TRIPHKNYLMETHANE DYESTUFFS. 83 Consequently, leuoaniline is a triamidotriphenylniethane, and the rosaniline base obtained from it, on oxidation, is a triamidotriphenylcarbinol /C,;H4NH., /CiHjNH., H \CbHjNh., oh ^CoHjira, (leucaniline). (rosaniline base). The determination of the positions of the amido-groups in the three phenyl rests was carried out in the following way : — When benzaldehyde is condensed with aniline in the presence of zinc chloride, diamidotriphenylmethane is produced /C,;H, H.C,.,HjNH„ / CsHjCHiO + -^ C( — C„H,NH„ H.;C6H4NH„ I \. H ^CeHjNHj In the same way ^>amidobenzaldehyde condenses with aniline to form a triamidotriphenylniethane (leucaniline), in which the position of one amido- group in reference to the methane carbon atom follows from the method of formation (4) /NH., CsH/ ' : \CHO HCsHjNHj H.CiHjNH, /C„H,NH, (1)/ -5. C:^ C„H,NH, H ^C H NH (leuoaniline). This amido-group is not either of those contained in the diamidotriphenyl- methane mentioned above, and it is therefore only necessary to determine the positions of the two amido-groups in this substance in order to elucidate the constitution of leucaniline. This was done in the following way : — Diamidotriphenylmethane, on treatment with nitrous acid and boiling with water, is converted into dihydroxytriphenylmethane /CcHj /C^Hj _/ _,„ nitrous acid and _/ _____ C^ CsH^NH, T— p — — ~> C( — C6H4OH I \ " ^ - boiling with water 1 \ " * H ^CoH^NH, H \Co,H,OH (dihydroxytriphenylmethane) which, on fusing with caustic potash, is converted into dipara-dioxybon'/ophenone according to the equation /CijHs / /CsH.OH 0( CfiH,OH + -s. C0< + C,H„ I \ \C,jH,OH H \c,;H,OH This substance had previously been prepared by Diibner {Ber., 1879, xii. 1466), and in it the para-position of the two hydroxyl groups to the ketone group had been clearly established. 84 SYNTHKTIC DYKSTUFFS. It therefore follows that the two nmido-groups in the diamidotriphenyl- methaue are in the para-positions to the methane carbon atom, and hence that the three amido-groups contained in leucaniline are also in the para- position. The formulae, therefore, of leucaniline and the rosaniline base are H \<^NH, OH \<^NH, (leucaniline). (rosaniline base). Shortly after the discovery of M.igenta, Hofmaun (Ann., 1864, cxxxii. 296) showed that pure aniline did not give this dyestufF on oxidation, but that the presence of ^-toluidine is necessary for its formation. This is explained on the assumption that the oxidising agent first acts on the methyl group of the /(-toluidiue, converting it into the aldehyde group, which then condenses with 2 mols. of aniline to foiTn the base of the dyestuff. Thus : — (4) (4) (1) /CsHjNHl, (1) .C^.NH: (1) CH3/ +0., -^ C( HO 1 ^O (;>toluidiiie) H (4) . .C.H.NH.. (1) /CcH^NHo ! H. C,H,NH:, / (2) 04 : "■ + " -» C'^— C.HjNH., ^ HO I ^:0 H. C,.H,NH, I \ H H ^CgH^NHa \r (rosaniline base). In actual practice an equimolecular mi.\ture of aniline jwra- and ortho- toluidine are always used for the production of Magenta ; consequently there !•< always present a second rosaniline formed according to the equation Z"^^.*^... HC,H,NH, (J C-W. C^O + CH. (1) -* C C,H,NH, + HO \ '■ : HC,,H,>: I ^CH, (3) H "^NHo (4) (homorosaniline base). The name homorosaniline wiis given in order to distinguish it from the other, which had been called para-rosaniline. The latter name did not, however, refer in any way to the positions of the amido-groups, since at the time the name was given these positions were unknown. Laws regulating the formation ,of dyestuffs of the Rosaniline series. — From the foregoing elucidation of the cimstitution i>f the rosaniline base, it is evident that in order that bases may be used in their prepamtion they must conform to certain well df^finpd conditions. Thus, in the first place, one of" ihc bases must coutam a para-methyl group. TRIPHEN^^LMETHANE D\ KSTUFFS. 85 otherwise the requisite para-methane carbon atom cannot be furnished by oxidation. Cousequeutly neither ortho- nor meta-toluidine, either alone or in conjunction with aniline, can yield rosanilines on oxidation. Again, it is evident that two molecules of the bases used must have their para-positions free, since it is at tliis point that union with the methane carbon atom takes place. Tims para-tuluidine when oxidised alone cannot yield rosaniline d3'estuffs. Rosenstiehl and Gerber divide the liomologues of aniline into the three following classes : — (1) The para-derivatives, whicli yield rosanilines when oxidised together with two molecules of the bases of class (2) or of aniline, but not by them- selves. (2) The ortho-derivatives, which yield rosanilines when oxidised with the bases of class (1), but not when oxidised alone or with aniline. (3) The meta-derivatives, which under no circumstances yield rosanilines on oxidation. That rosanilines containing methyl groups in the raeta-position to the amido- group are capable of existence has been demonstrated by E. Noelting, who has prepared a leuco-base of the formula >N{CH; which gives blue rosaniline dyestufts on oxidation. They are, however, pre- pared by indirect methods. Noelting has also shown that it is possible to prepare rosaniline dyestuffs in which one of the amido-groups is in the ortho- or meta-pusitions to the methane carbon atom. Thus the leuco-bases CC^^ -' and cCl--^ -• ^\> ^\> NH2 NH., yield rosaniline dyestuflFs on oxidation. If, however, less than two of the amido-gioups are in the para-pusitions, then no rosaniline dyestuffs are formed from the leuco-bases on oxidation. Formation of the dyestuff from the dye-base. Constitution of the Rosaniline dyes. — As already mentioned, the formation of the dyestuff from the dye-base is brought about by the action of dilute acids. On treating the carbinol base with hydrochloric acid, one molecule of water is eliminated and a monouhloride is formed ; by the further action of hydro- chloric acid a di- and a trichloride are formed, but these are produced without the elimination of water and must be considered as true salts caused by the passage of trivaleut into pentavalent nitrogen. Furthermore, the monochloride only is the true dyestuff, the further action of acid gradually destroying the colour. 86 RYNTHKTIC DYKSTUFFS. It is iirobable that, in tlie transformation of dye-base into the dye-salt, a change of constitution takes jilace, and that tlic trijiht'iiylniethane structure of the base passes into tiie ijuinonc structure of the salt (iV(V/.?/r/). Thus :— /CoHjNa, /C,;HjNH„ C^CeH^NHj + ^^^ C C„H,NH., ;\ OH ^CH^NHj C,,H4 = NH.HC1 (ilye-basc). ((|uinonc salt). The existence of a quinone structure in dyestiifl's of this series has received support by the discovery of v. Georgievics in the case of Magenta, and of Honiolka in the case of New fuchsiu of a second rosauiliue base, which is coloured, and which in all probability is the ammonium base corresponding to the ijuinone salt given above. c„H,NH._, c,h,nh:, C^^C.HjNHl, -> C C.H.NH., CiH, = im,Cl ^ C,;H, = NIL,OH (rosaniline chloride (Magenta)), (rosaniline ammonium l)ase). The existence of this second rosaniline base was shown by electrical con- ductivity experiments (Ilantzsch and G. Osswald, Bei:, 1900, xxxiii. 303), and it was found to be coloured and dissociated by potash, and therefore to behave as a true ammonium base. The carljiuol base, as already mentioned, is colourless, and is not dissociated to any appreciable extent. The carbinol base of Magenta is therefore incapable of direct conversion into salts. According to Hantzsch, it is a "pseudo-base," and, when transformed into the dye-salt, first undergoes conversion into the ammonium base, called by him the " rosaniline base." /^C,.HjNH., C„H,NH, ^ C,;H,NH, Cr— C„H,NH:, u.\iclatii.ii C— C.H.NH, -» C — C.H.NH. I \\ ' I \ ' " \ H ^C,;HjNH., OH C,;HjNH, \C,;H, = NH,OH (leuco-base) (pseudo-base) (rosaniline base) (colourless). (colourless). (coloured). /C.HjNH, -* C^ C,-H,NH., C,;H, = NH,C1 (rosaniline salt (dyestufl') ). According to Hantzsch and Osswald, the other coloured bases of this series behave in a similar wav. the general fornnila of these amiiKinium bases being ^C„H, = NR,.OH where R- hydrogen or any monovalent hydrocarbon radical. TRIPHENYLMETHANE DYESTUFFS. 87 Another view concerning the constitution of rosauiline chloride is that advanced by Kosenstiehl, according to which rosaniline is a tertiary alcohol and its chloride the chlorine ester thereof. c{-- aH,NH„ -> C— CeH^NH, OH \C6H4NH,, CI CjHjNH., (rosaniline base). (rosaniline chloride). Apart, however, from any question concerning the salt-like character of rosaniline chloride, this view is rendered improbable by the very ditierent properties exhibited by a cyanide of this formula prepared by E. Fischer and W. L. Jennings {Bei:, 1893, xxvi. 22-21). This substance, which undoubtedly has the constitution C< — CeHjNH., I ^\ CN ^CsH.NHi, is colourless, insoluble in water, and unacted upon by cold alkalies. It is interesting to note that Otto Fischer has found that ;)-amidobenzyl alcohol OH.CH.,.C„H,.NH., behaves very similarly to rosaniline on conversion into its hydrochloride. Thus when treated with hydrochloric acid the normal colourless hydrochloride is formed OH. CHj. CoHjNH,. HCl If this is heated at 100° C, water is eliminated, and a coloured chloride is produced, which possesses the property of dyeing silk yellow from an alcoholic solution. On dissolving in water the coloured chloride again becomes colourless, owing to its reconversion into the normal hydrochloride. Methods of formation. — The following methods are in use for the preparation of members of the Rosaniline series. (I) By the oxidalion of p-amines together with such bases as are capable of yielding rosanilines (see p. 85). /CeHjNHo .NH, / Qh/ ■ + 2aH5NH, + 03 -> C( CsHjNH., + 2H.,0 ' ^CH. ' I \. OH ^CeHjNH, (p-toluidine). (aniline). (rosaniline base). Arsenic acid and nitrobenzene are the oxidising agents most usually employed. The latter has now, however, practically superseded the former,^ since, in consequence of the impossibility of freeing the finished dyestuff from the last traces of arsenic, the product formed by the former agent frequently possessed poisonous properties. The process is more fully described on p. 244. ' For the jiroduction of large crystals for export this method is still employed. 88 SYNTHETIC DYESTDFFS. In the production of Magenta, the yellow dyestuflf Chrysaniline occurs as a bye product ; this is evidently formed by the occurrence of a partially ortho- condensation, giving rise to the substance / I ^\ nh:, H \. which, on further oxidation, is converted into Chrysaniline. I I Chrysaniline is, therefore, a diamidophenylacridine. (2) The Neir furhmi process [M]. — Formaldehyde is condonsid with aniline to form anhydroformaldehydeanilinc CH, OfH., NC5H5 -5. CH.,: NC,,Hi + H,0 (forinaldeliyili'). (aniline), (anhydroformaldeliyde- aniline). On heating tliis substance with aniline and aniline hydrochloride it is converted by molecular rearrangement into diamidotripheuylinethane CH^: NCsHs + CeHjNH., -> CS., = {C^S.j!rS.X This latter substance is readily converted into Magenta on heating with aniline hydrochloride in the presence of an oxidising agent ; and the process is capable of wide application, since many bases other than aniline can be used, giving rise to other dyestuH's of this series, (3) J'liosgetie proc£s$ [B]. — When phosgene gas, COCL,, is allowed to react on dimethylaniline in the presence of zinc chloride, tetraniethyldiamidobenzo- phenone is formed H C, Hj. N(CH,V. C, H,. N[CS.;\., CO CI., r -> CO. " i -HCl H C,HjN(CH,)., C„HjNiCHJ., (phosgene), (diniethylaniliue). (tetrametliyldiamido- beuzoplicuone). This ketone, on treatment witli phosphorus o.xychloride, is converted into the dichloride .CoH,N(CH,), CCL/ ' X!,S,N(CH3)j which condenses with many base.^, forming derivatives of rosanilinc. TRTPHENYLMETHANE DYESTUFFS. oq (4) By condensing tetra-alkylated diamidobenzliydrol ,C,H,N(CH..), CHOH< ^C,.,HjN(CH.:)„ prepared by the oxidation of tetramethyldiamidotriphenylmethane, with bases and phenols [By]. General description of the dyestuffs of the Rosaniline series.— The Rosaniline dyestufl's, except in the form of their sulphonic acid (to be described later), are basic dyestnfFs, dyeing wool and silk direct, but requiring the aid of tannin to affix themselves on the cotton fibre. Magenta (Fuohsin, etc.) occurs commerciallj* as the chloride (more rarely as the acetate) of para- and homorosaniline. The mixture of bases, aniline, o- and ^i-toluidine, used in its formation is known technically as " Aniline oil for red." The purest form of Magenta is known as Diamond magenta, and finds application rather as a basis for the preparation of other dyestuffs of the series than for use as a dj-estufF itself. New fuchsin [M] is tritolylrosaniline chloride (3) (4) / (3) (4) &— CsHsCCH^) - NH., (3) (4) " C6H3(CH3)=nh:,ci and is produced from o-tuluidine by the New fuchsin process (see above). If the hydrogens of the amido-group in Magenta are replaced by alkyl groups, violet dyestuffs are formed, which approximate more closely to the blue or red, according as the number of alkyl groups is greater or less. The methyl violets are a number of dyestuffs belonging to this series in which the letters 11, 2R, 3R, B, 2B, 3B, etc., are affixed in order to denote the red or blue shade of the dyestuff. The most usual method adopted in their preparation is to oxidise dimethyl- aniline with cupric chloride in the presence of phenol. The course of this reaction is as follows : — A methyl group of the dimethylaniline is oxidised to formaldehyde, which condenses with the resulting methylaniline and two molecules of the unaltered dimethylaniline to form pentamethylrosaniline. The bluest methyl violet, methyl violet (6B), that can be prepared by this method is made by treating pentamethylrosaniline with benzyl chloride, thus converting it into the benzyl derivative. It therefore has the constitution /CsHjNCCH^),, C— CeHjNlCH,,)., Hexamethylrosaniline chloride is known as Crystal violet ^•C,H,N(CH,).3 C^CsH^N(CH,)., ^C6Hj = N(CH3)„Cl and is prepared by the phosgene method. 90 SYNTHETIC DYESTUFFS. Hofmann's violet was the first violet dyestuff of this series prepared, and is now merely of historical interest. It is trietliylrosaniline iodide ^CeH.NH.C.a, c{ CoHjNHC,H, By the addition of alkyl iodides and chlorides to the violet rosaniline dye- stutVs, there are formed a series of green dyestuffs, which are addition products of the alkylated rosaniline salt and the alkyl hidogen coni]iound. They liave for the most part been replaced by other green dj-estufis, since, being q\iaternary salts, they arc split up at a comparatively low temperature into the alkyl lialogen compound and the violet dyestufl' from which they were derived. Iodine green is prepared by treating methyl violet with methyl iodide. Its formula is /CoH.NCCH,)., C^- Cr,H,N(CH3)., + CH3I C„Hj = N(CH,)I At one time this dyestulf was very largely used, but was soon replaced by the corresponding Methijl (jrcen /C,,H,N(CH.,)., C^ C,HjN(CH),, + CHCl C,,H, = N(CH.,),C1 prepared in a similar way from methyl violet and methyl chloride. This dyestutr is still, to some extent, used for the dyeing of cotton on a taimin mordant, for which purpose it is better suited than Malachite green, which has, however, completely replaced it as a wool dye. Phenyl and tolyl derivatives of rosaniline.— On heating rosaniline with aniline or toluidine in the presence of acetic or benzoic acid, there are formed, in the first instance, violet dyestufls which consist of mono- and diphenyl (or tolyl) rosanilines ; these, by the further action of aniline or toluidine, pass into the blue dyestufls known as the Ro^anUine Uucf. The compound formed from aniline and rosaniline therefore has the formula (hydrochloride) C"^ CHjNHC.H C„Hj = NHC„H;,Cl and was discovered by (Jirard and do Laire in It^Gl, the first product, which was insufficiently phenj'latcd, and therefore of a violet shade, being sold under the name of Lyons blue. The aniline used in the product of this Rosaniline blue must be quite pure ; technically it is known as " Aniline oil for blue." The introduction of three phenyl groups into the rosaniline molecule, one attached to each nitrogen of the three amido-groups, represents the extent to which rosaniline can be phenylated. It is apparently impossible to introduce TRIPHENYLMETHANE DYESTUFFS. 9 1 two phenyl groups on to the same nitrogen atom. The dyestuffs prepared in this way are insohible in water, but readily become soluble on treatment with sulphuric acid (see AlkaJi hlue, etc.) ; they are therefore of little importance by themselves, but serve for the production of their important sulphonic acids. DiphenylamiiK blue, which is isomeric, but not identical, with Rosauiline blue, was prepared in 1866 by Girard and de Laire, by heating diphenylamine with oxalic acid, and for a considerable time competed successfully with Rosaniline blue. A number of important dyestufTs of this group are manufactured by the Badisohe Aniline and Soda Fabrik from the tetraalkyldiamidobenzophenoues. Thus Victoria blue B is prepared by condensing tetramethyldiamidobenzo- phenone with phenyl-a-naphtliylamine, and therefore has the constitution C,;HjN(CH3), C-^C„H4N(CH3)„ Ci„Hs = NHC6H5Cl Other dyestuffs prepared from this ketone are : — Virtoria blue 4R, with methylphenyl-a-naphthylamine, and Victoria blue R, with ethyl-a-naphthylamine. Night blue is prepared from tetraethyldiamidobenzophenone and p-tolyl- a-naphthylamine. It possesses the curious property of forming insoluble com- pounds with certain dyestuffs — such as, for example, Picric acid and Naphthol yellow S — which causes it to be used in the quantitative estimation of these compounds (see p. .308). Another interesting series of colouring matters which belong to the triphenylmethane series are the Chrome colours of Fr. Bayer -tolylamine, >NH.C6H,CH3 OC2H5 The following dyestuH's are formed by the sulphonation of Rosaniline blue : — Nichohoii blue or Alkali blue is the sodium salt of the mouosulpboaic acid of Rosaniline blue. It is largely used as an acid wool dye. Its method of application is, however, peculiar. The wool is first boiled in a solution of the dyestull" made alkaline with borax, when the dye is affixed to it in the form of an almost colourless derivative. The colour is developed on treatment with dilute sulphuric acid. \Vafer blue, Cotton blue, Xary blue, K>olulile blue, etc., are names given to a number of blue acid dyestuffs which are for the most part mixtures of the ammonium (or sodium salts) of the di- and trisulphonic acids of Rosaniline blue. It is worthy of remark that these sulphonic acids are to some extent capable of forming lakes with tannin, and hence can be used as cotton dyes on a tannin mordant. Other dyestuffs of the Rosaniline series not mentioned above are : — Ethyl violet [B] /-CH.N^CJHj),. C— CsH^NlCSjl., Red violet 5RS [B], mostly /C6H3(NH.,)SO;,Na ,/_ \C,.H:,^CH , (NH., SO^Na Red violet -iRS [B] C,H NHCH SONa \CeBL,(CH,)(NHj)S03Na TRIPHEXYLMETHANE DYESTUFFS. 93 Fast acid violet lOB [By] /C6H,N(CH.,)., HO - C^ C|iHjN(CH3)., Alkali violet [B] Hcichst new blue HO - 0^C6H,N(C,JI,),, ^CeHjNlCHsJCeH.SOjNa /CsH4N(CH3)C6HjSO.,Na HO - C^ C,iHjN(CH3)C6HjS03Na C6H^N(CHo)CeH,S03Na \ \, (c) The Rosolic Acid Dyestuffs. Eosolic acid belongs to the oldest of the artificial dyestufis, having been prepared by Ennge in 1834. In 1861 Kolbe and Schmidt, and Jul. Persoz independently, discovered that it could be prepared by heating together phenol and oxalic acid with sulphuric acid. The constitution of Aurine follows from the fact that its leuco-compound can be prepared from leucaniline by treating it with nitrous acid and boiling with water /CfiHjNH, /C.H.OH / ' HNO„ / 0— CH.NK, ^-^j^^„ C^C«H,OH I \ with water. 1 \ H \C,;HjNH. • H ^CsHjOH (leucaniline). (leucaurine). And also from the fact that on heating with water at 220° it is broken up into phenol and y>dioxybenzophenone. -CiHjOH (4) / (D/CeH.OH C^ CsH.OH H.O C0< + aH-GH \ -- ^ (1)\C6H,0H ^CeH, = (4) (Aurine). The dyestuflf rosolic acid {Aurine) is directly formed by the oxidation of its leuco-compound /C„H^0H /CjHjOH C^— CgHjOH -* C— C,H,0H I \ ' H ^CeHiOH C6Hi = The intermediate carbinol / C„H,OH C- — CeH^OH 1 \ OH CgH^OH 94 SYNTHKTir DVKSTUFFS. appears to be incapable of existence, although Herzig has succeeded in preparing its triacctyl derivative. Since Amine can be prepared from rosaniline, it is obvious that two dyestuffs exist corresponding to para- and homorosaniline respectively. They are called (pararosolic acid (Paraaurine) ), derived from pararosaniline, and /CH, ,/ ^OH C^ — CoH.OH X CcH4 = (honiorosolic acid (Homoaurine) ), derived from homorosaniline. As already mentioned, Aurine is prepared by the action of sulphuric acid on a mi.xture of phenol and oxalic acid. This reaction is explained on the assunifition that the carbon dioxide (from sulphuric and oxalic acids) supplies the necessary methane carbon atom, and that the condensation ensues according to the equation H C„H,OH . O / H C.H.OH CcH.OH -> C C^H.OH C„H, H H ^CjH4 = Aurine is no longer used as a dyestuft' in the strict sense of the term. Owing, however, to its sensitiveness to alkalies it is frequently used as an indi- cator in alkalimetry. Paoonine (Red corallin) is prepared by heating crude Aurine (Yellow corallin) with ammonia under pressure. It is used for producing shades varying in colour between ^Magenta and Cochineal, and probably consists in part of a rosolic acid salt of /)-rosaniline. Lately compounds belonging to this group have been prepared b}' a process analogous to the New fuchsin process described on p. 88. Thus Aurine can be prepared in the following way : — HiCjH.OH CHjiO + -» : H iCoH^OH ,CoH,OH CH,< " X!oH,OH (formaldehyde). (phenol). liioxv-iliplu'iiylmctlianc) /C„H,OH C.H.OH 0^ H, 1 C,,H,OH + 0., -> C — C,;H,OH CsH.OH C,H, = (Aurine). TRIPHENYLMETHANE DYESTUFFS. 95 By replacing the phenol by other substances — such as resorcinol, pyrogallol, etc. — dyestuffs analogous to Aurino have been prepared. Thus CJirome riolet [R. Geigy of Basle] is OH / ^COOH / .OH ^£ C^H,/ X^ ^COOH ^C6H3(COOH) = and is prepared from formaldehyde and salicylic acid. The Influence of Groups and Constitution upon the Colour of Compounds of the Triphenylmethane Series. Probably no other series of dyestuffs illustrates to such a marked extent the influence of the auxochrome groups, NHg and OH, as the compounds of the triphenylmethane series. Thus Magenta is red, hesamethylmagenta (Crystal violet) is violet ^CeHjNH, yCeS.^N{CH.3), C^CeHiNH, C^CeH^NCCHj)., \ CsHj = NH2CI ^ CfiH^ = N(CH.,),,C1 (red), (violet), and the various brands of the methyl violets are intermediate in colour between red and violet, according as more or less of the hydrogens of the amido-groups are replaced by methyl. If, however, the methyl groups enter into the benzene nuclei, the colour of the dyestuff is not appreciably affected. Thus New fuchsin CH, NHL, ^C6H3(CH3) = NH2C1 is red. By the elimination of one of the amido-groups in ilagenta, green dyestuffs are produced. For example, Malachite green yC^MJSiCS..,)., C^CeHj ' C,.,Hj = N(CH3).,Cl The same change in colour takes place if, instead of the amido-group being eliminated, its basic character is destroyed by the entrance of acetyl groups. Green dyestuffs of the triphenylmethane series are also produced by the addition of methyl chloride to the violet hexamethylrosaniline chloride. 96 SYNTHETIC DYKSTl'FKS. Thus Methyl green is C.HjNCH,)., C" CH.NCH,), + CHjCl C„B, = N^Ca,),.Cl If two atnido-groups in rosaniline are lacking, the colour of the compound is not quite destroyed. Thus /)-monoamidotriphenylniethane chloride C„H, = NH.,C1 \ is orange yellow, and will affix itself to tannined cotton. By the entrance of phenyl groups in place of the hydrogens of the aniido- groups in rosaniline, the colour gradualh- passes from red to blue. Thus the highest phenylated rosaniline — triphenylrosaniliue chloride — C^CoHjNHC,H \C,,H^ = NHC,H,C1 is blue. The replacement of the amido-groups by hydro.xj'l groups gives rise to the Auriues, which are yellow. C,Bj = NH.,Cl C„H, = (red). " • (yellow). The entrance of siilphonic acid groups into the molecule of rosaniline and its derivatives apparently does not appreciably affect the tone of the colour, although its colour-strength is thereby considerably diminished. This is, however, counterbalanced by the increased solubility of the dyestuff in water. CHAPTER XV. PYRONINE DYESTUFFS. The dyestiiffs of this group contain as chromophore the para-quinone ring and as chromogen tlie pyronine ring O I J I I c I Tliey can be divided into — (1) Diphenylmethane derivatives, comprising the Pyrouiues. (2) Triphenylmethane derivatives, comprising the Phthaleins. (1) The Pyronines. Dyestuffs of this class are produced by the condensation of dialkyl TO-amidophenol with aldehydes and acids of the aliphatic series. Pyronine G [L] /v °v /\ ^N(CH3),C1 is prepared, according to E.P. SGTS*'', 13,217*^, and 18,600^^, by the condensation of formaldehyde with dimethyl-Ht-amidophenol to form tetramethyldiamidodioxy- diphenylmethane N(CH.,)o h c,h, OH (1) .N(CH,), H C,jH.< 1 ■■ "^-OH (4) (2) \h OH H C,H3/ \N(CH3)., 1 -X /OH H \CeH3< (1) \N(CH3), (2) (4) (formaldehyde}. (dimethyl-«i-amidophenol). (tetramethyldiamido- dioxydiphenylmethane). In this compound the hydroxyl groups are in the ortho-position to the methane carbon atom, and therefore, as will be found to be always the case in 97 7 98 SYNTHKTIC OYESTUFFS. dyestuffs of the Pyronine and Phthalein series, readily split ofl" water to form the anhydride k: y<( ~)>N(CH,), N;^ )>N{CH;), (tctrametbyldiamidodiphenj-lmethauc oxide), wiiich, on oxidation and conversion into the salt, forms the dyestuff ^ Xy\ N(CH,),C1 I H Pyronine B [L] is a similar compound prepared from dietliyl-//(-amidoplienol ; it is converted into AcrvHne rcl (K.P. 123r''-') I OH on oxidation. The Pyronines are more or less yellowish-red, fluorescent, basic dyestufls, which are chiefly used in the dyeing of tannined cotton. According to D.P. 65,739, dyestufls of this class containing sulphur in the place of oxygen can be prepared by the action uf S.,0,, on alkylated diamido- diphenylmethanes dissolved in concentrated H.SO,. Their constitution would be represented by the formula /C,-,H,N(CH,,)., %C6H,N(CH3),C1 (2) The Phthaleins. These dyestufTs are produced by the condensation of phthalic anhydride with phenol or amido])henols, the condensation being usually brought about in the presence of some dehj'drating agent, such as zinc chloride, sulphuric acid, etc. The most typical instance of the formation of a ]ihthaleni is shown in the formation of phenolphthalein from phthalic anhj-dridc and phenol (^ae^er, 1871). These substances luiite in accordance with the equation 00 CO CeHjC^ No H C.H.OH -> C^'h/ \o H,0 C O H C.H.OH \^/C,S,OH C„H.OH the hydrogens in the para-positions of the two phenol molecules reacting with the oxygen of one of the carbonyl groups. PYRONINE DYESTUFFS. 99 The correctness of this formula is shown by the fact that phthalyl chloride CO c„h/ >0 also combines with phenol to form phenolphthalein. In the formation of phenolphthalein, however, a certain amount of the product consists of r)-phenolphthalein anhydride, which has obviously been formed by the combination of the phenol molecules in the ortho-position, with subsequent elimination of water It is this substance which may be considered as the chromogeu of the phthaleni dyestuffs, since by the entrance of auxochrome groups into its molecule, bases or acids are formed which, when converted into their salts, yield the Rhodamines and Eosines. Just as in the Triphenylmethane series and in the Pyronine series already dealt with, the transformation of bases or acids of these dyestuffs into their salts is assumed to be accompanied by a change of constitution from the phthalein form into the quinone structure (seep. 107). Thus CO OH/ CeH,< >0 Y< >0 \<__>0H {Fluorescein (acid)), gives the sodium salt (Uranine) O NaO/N/X/^v/^ C /\C00Na SYNTHKTK" DY KS ir KTS. rtiiil liliodainine I'. []'.] (base) CO >N(C.^5)2 'ives the chloride (C._H5)J»| I I I C COOH f I' \/ The relationship that exists between the members of tlic plitlinlein series and trijiheiiylmcthane is shown by the following facts : — Fhthalyl chloride condenses with benzene in the presence of aliiiniiiiinn chloride {Friedel and Graft) to form phthalophenonc CO /\ C,H,>( ^O \ /■', C,,H, /CO ^ c^,<^ yo + ^0 01 J \f H C„H, H C,,H, or if written as a triphonylmethane derivative C,,H,, C,H , (phthalophenone), ,/ "CoH, ^C„HjCO / This substance can be either (1) converted into phenolphthaliMn by nitration, reduction, diazotisation, and boiling with water /C,|H5 ^CHjCO / \o/ C.H.NO, C.^— ^CH.NO, V^C„H,C0 \ / \o/ /C^HjNIL, c{— CiHjNH., :\ ^C„HjC0 \ / ^0/ ,C,H.0H C^CjH.OH r\ A C^HjCO ( phenol phthaleni), PYRONINE DYESTITFFS. lOI or (2) converted into triphenylmethaiie by treatment with alcoholic KOH, reduction, and dry distillation OH ^CsHj.COOH H ^CeH^COOH /CgHj (triphenylmethaue). The Rhodamines. These dyestuffs are phthaleins, derived from the combination of dialkyl- rM-amidophenol with phthalic anhydride. The Khodamine B already mentioned is typical of their constitution. They are basic dyestuffs, dyeing wool and silk direct a bluish-red showing strong fluorescence. On tannined cotton this fluorescence is lost, and the colour appears as a dull shade of lilac, but it is retained if the cotton is mordanted with Turkey-red oil and alumina. By etherificatiou (replacement of the hydrogen of the carboxyl group by CjHj), Ehodamine B passes into Rhodamine 3B [B] C1(C.^5)2N. \/X/\/\ III C jN.CCjHs), An interesting dyestutf, belonging to this group, is prepared by condensing succinic anhydride with dimethyl-?«-amidophenol. It is known as Rhodamine S [B], and has the constitution (chloride) CKCHsJ^N^ |N(CH3)2 C^H^COOH It is a substantive cotton dye, dyeing unmordanted cotton a fairly fast shade of pink. Other dyestuffs belonging to this group are : — Rhodamine 6G [B] CIO2H5HN, .cooes. \/ I02 SYNTHETIC DYRSTUFFS. Rhodamine O [B] OOH r? and the following sulphonic acids (made by the sulphonation of the condensation product) : — Fast acid violet B [M] — Viohiininu 1! C^.N^ /^^ /^/NH.C„H,SO,Na f I f I C I^COOH \y Fast acid violet A, 211 [M] — Violamine R CH,.C„H,.N^ ° I I d /\|COOH Acid rosamine A [MJ^Violamine G (CH3),,C,^N^ ° -^NH.C„H(CH3)3SO,Na C ,/^,COOH and Fast acid blue R [M] — Violamine 3B (CaH^OlCsH^N, ° ■^/^^ -'^NNHCeHjCOCjHs). SOjNa cv /\C00H CI The Eosines. These dyestuffs are prepared by the condensation of phtlialic anhydride with di- and trihydric |ihenols. Most of the members of lids group are, however, derived from Fluorescein, which is prepared by the condensation of phtludic anhj-dride and resorcinol in the presence of zinc chloride. VYRONINE DYESTUFFS. The free acid has, therefore, the constitution O wliilst tlie sodium salt, which is found in commerce under the name of Vraiiine, has the constitution O It is an acid dyestuff, forming solutions in water which exhibit a reraarkiible green fluorescence. It is, however, of little nnportance. Another dyestuff of this group is Chrysoline [Mo], which was prepared in 1877 by Reverdin by the interaction of resorcinol, phthalic anhydride, and benzyl chloride in the presence of sulphuric acid. Its sodium salt is best represented by the constitution It is chiefly important as a silk dye. In 1874 Caro found that Fluorescem was capable of absorbing bromine, and was thereby converted into a red dyestuff, to which he gave the name Kosine. Kosine A [B] is a tetrabromofluorescein containing two bromine atoms on each of the benzene rings of the two resorcinol residues, and as sodium salt has the constitution ~. Br O Br c |-^^|COONa \/ These positions have been determined in the following manner : — By boiling Eosine with caustic soda a dibromodihydroxybenzoylbenzoic acid COOH '\cO.CeH(OH)2Br., is produced {A. Baeyer). In this substance the bromine atoms must necessarily occupy the same positions as they do in one of the benzene rings of Eosine. I04 SYNTHKTIC DVESTl'FFS. Its constitution has been determined by G. Heller, who succeeded, by the aid of fuming sulphuric acid, in converting it into an already known dibromo- xanthopurjnirine Br ,/^,COOH /" OH j-CO Br OH \y' Br ^-CO-^'^,OH V-°°- /Br OH Finally, R. Meyer, by heating it to a tempierature above its melting-point, transformed it into Eosine and phthalic acid. Tills reaction, which evidently takes place in iiccordance with the following equations : — K > (Eosine\ H Br I Br Br osf Y Y y Br\ X A /Br definitely establishes the positions of the bromine atoms in Eosine. Eosine is used more especially as a silk dye, upon which the shades produced are yellowish-red showing a marked fluorescence. The following list gives the various dyestuffs of this group which are produced, some by the entrance of other halogens into Fluorescein, others by the conversion of Eosine into its derivatives. Spiril eosine [TM] and /■hsinc S [B] are the methyl and ethyl esters of Eosine respectively, constituted according to the formula -■■rrrg^ c ,COOK Eosine BN [B] Erythrosine G [B] Erythrosine [B] Phloxine P [B] PYRONINE DYESTUFFS. o=nv\A ^0K /NO, COOK OK I I c ,COOK I I' , I O I ll I I 1°^ - c l^^jCOONa ~ Br O Br fill c Cl'x "^^COOK CI 105 Isomeric compounds are Spirit cyanosine [M] and Cyclamine [Mo] Eose Bengal [B] Phloxine [M] iOK f. Br O Br \/\/\/\0K (III c Cl,/^,COOK C1\/C1 CI I06 SYNTHETIC DYESTDFFS. and Rose Bengal 3B [M] O ^ ^ C1,/\C00K CI The above compounds, which contain chlorine in the phthalic residue, are derived from dichloro- and tetraclilorophthutic ncid rcsj)ectively. Galleine and Coeruleine. These are two dyestuffs which, owing to their method of formation, are classed among the phthaleins, but which in their application are more akin to the next group of dyestuffs, that of the Alizarine series. They arc mordant dyes, forming, in the ciise of Galleine, blue ; and, in the case of Crerulenie, green lakes with chromium salts. Galleine [B] is formed by heating phthalic anhj'dride with gallic acid at 200°. .Since at this temperature gallic acid breaks up into pyrogallic acid and carbon dio.xide, it is evidently the former which condenses with phthalic anhydride, according to the equation CO CO c^,/ V/<^^>°= CeHi >0 \ ^ / OH OH X ^ ' HC„H,(OH), ^C < CO + " wn OH OH HC,JH.,(OH), "-^ , / , ■ " ■ ^< >= The empirical formula of Galleine is, however, Q,oH,.,0;, and its constitution, according to Orndorff and Brewer (Amer. Chem. ■/.,"l90'l, 97; also J.C.S., 1901, abs. i., 724), is Q OH O OH j-^lCOOH \y This formula is derived from the above by the elimination of water and conversion into a quinone structure OH OH OH OH Q OH O OH oHi-^^oH OH^OH OH y y ^^H y y y ^oh \/\ /\/ HO \/V^- « - o \y PYRONINE DYESTUFFS. I07 Ceeruleine [B] is prepared by heating Galleine with concentrated sulphuric acid at 200°. According to Orndorff and Brewer {loc. cit.) its constitution is represented by the formula OH O OH Q OH O OH "iOH ^i-'^i^^i |OH C iH -H,0 ,C0 OH I (Galleine). (Ca?ruleine). Like Galleine it is insoluble in water, and is usually fixed on the fibre by the aid of its chromium lake {Green). It is generally found in commerce in the form of a 10 per cent, paste. In the form of its soluble bisulphite compound it is known as Coendeine S. The Constitution of the Pyronines. — The experimental data upon which it has been assumed that the transformation of the colourless Ehodamine base into its intensely coloured salt is accompanied by a change of constitution from the lactone to the quinone form CO , ,COOH / /O ^/ ^6^4 y CgHj^^ /CeH3N(C.>H5), /C,^,N{0.^,)2 \c/ \o VoeH3 = N(C2H5)2Cl C< >0 are as follows :- - A Rhodamine of the above constitution gives an ethereal salt when treated with an etherifying agent, such as alcohol and hydrochloric acid. This ethereal salt is readily hydrolysed to the corres|ionding acid, and therefore cannot be a quaternary ammonium salt of the formula CO O^H, ;0 / /CeH-NCCajjoCSsCl XCeHjNCCoH^), but must have the constitution represented by ^COOCS. /" 0^'B.i< /CeHoNlCoHs), ■^c-{ \o ' C6H3 = N(C2H5)„C1 Strong support has been given to this view by the work of Xoelting and Paira, who condensed nitrobenzaldehyde with Hj-amidophenol, effected the closing io8 SYNTHETIC DYKSTUFFS. of the pyrone ring by eliminating water from tlie hydroxyl groups, and finally di8|il:iced the nitro-groiip by carboxyl. The dyestuffs thus formed, wliich must, from their mode of preparation, con- tain a carboxyl group, are very similar in character to the Rhodamines ; they are represented by the formulaj r? OOH C / '•C,^,N(R).. \ >° ' \C,B3 = NCE.),C1 (From w^-nitrobenzaldehyde. ) COOH and '\/' /CAN(RU c / yo CeH3 = N(K,Cl (From />-nitrobenzaldehyde.] By analogy. Fluorescein should have the constitution /^ 0^4<^ / \ /CftOH \C< > ^ C„H,OH whilst its intensely coloured sodium salt should have the constitution COONa ^^*\ /C-HsOH \c/ >0 \C„H, = This question has been thoroughly investigated by the researches of O. Fischer, llepp, Nietzki, and Schroetcr, who find that this substance may exist both in the lactone and quinone forms, the former being the more stable of the two. For example, Nietzki and Schroetcr found that on treating Fluorcscin (prepared by the reduction of Fliioroscein) with alcohol and hydro- chloric acid it was transformed into an ethyl salt ,COOH C,^i\ COOCH, CfiH,<^ \ H which, on oxidising and eliminating water, was converted into a corresponding ethyl salt, which must have a quinone structure C„H, COOC5H5 \ /\ /^ 1V - H„0 )>OH ^coocja, "•»•< XII PYRONINE DYESTUFFS. IO9 By the bromi nation of this quinone ester thej' obtained an ethyl salt of Eosiue, from which it follows that the Eosines also possess a quinone structure. By the further etherification of the quinone monoethyl salt of Fluorescein mentioned above, they obtained a diethyl salt of the constitution (yellow) M.P. 159°, which is isomeric, and not identical, with the diethyl salt of the constitution CO Y< > (colourless) M.P. 181-182°. (Nietzki and Schroeter, Ber., xxviii. 47.) By the alkylation of Fluorescein salts, the production of the coloured qninone diethyl salt is always accompanied by that of the colourless lactone diethyl salt. The remarkable colour-change which takes place when the colourless phenol- phthalein is converted into its alkali salt is also considered by Bernthsen and F'riedliinder to be due to a change from a lactone to a quinone structure CsHA >0 C,,hX \y .CeH.OH \ /^6-tt4"-tt "^ \C,H,0H '^C„H, = (Lactone form). (Quinone form). There is, however, no direct evidence of the existence of this substance in a quinone form, the phenolphthaleinoxime COOH which was prepared by Friedliiiider in support of his view, having been shown to possess another constitution, possibly that represented by the formula (H. Meyer, J.C.S., 1899, abs. i., 707) ,C:(N0H.}CgH40H CjHX (Seep. 111.) I lO SYNTHKTK^ DYKSTUFFS. Further, Herzigaiul Meyer prepared a colniirless lactone ctliyl salt bj' alkylat- ing plii'nol]ilitlialcin in alkaline solution, that is, in that condition in which it is assumed to possess a quinone structure ; and Bistrzycki and Nencki, under the same conditions, also prepared a colourless benzoyl derivative by the action of Vjenzoyl chloride. The exact behaviour of phenolphthalein with alkalies is as follows : — When the alkali is first added to a colourless solution of phenolphthalein in dilute alcohol, an intense rod coloration is produced, which disappears on the addition of excess of alkali or of alcohol. This behaviour was explained by Ostwald ( Wissetiscliaftl. GrundlcKjen der analijt. C/urmie, IP" Aufl., p. 116) on the theorj' of electrolytic dissociation, by which it was supposed that whilst phenoljththalein itself and its undissociated salts are colourless, its ions are red, and that the disappearance of the colour on adding an excess of alkali or alcohol denotes the suppression or retrogression of ionisation. This view was adopted by Herzig and Richard Meyer (Herzig, Ber., 1895, xxviii. 32.'J8; 1896, xxix. 138; U. Meyer, Jalirbucli d. Chem., 1899, ix. 404) and by 0. Fisciier {Zcit. Farb. Text. Chem., 1902, i. 281); whilst, quite recently, R. Meyer and O. Spcndlcr (Z^ec, 1903, xxxvi. 2919), after a careful re-examina tion of the facts, have come to the conclusiim that it still offers the best explana- tion, and that the (juinoiie theory does not give a .satisfactory solution. Some recent work by Green and I'erkin {J.G.S., 1904, Ixxxv. 398) shows, however, that this apparent exception to the quinone theory can be explained in the following way : - If the ionisation of the alkali salt of phenolphthalein is suppressed by an excess of alkali, it is reasonable to suppose that the colour will return on neutralising this excess. This, however, is not the case, since the strongly alkaline solution can be neutralised with acetic acid and still remain colourless. A (luantitative experiment showed that this neutr.il solution contained a potassium salt of the formula C.j„H|,,Or,K, and that, when boiled, it assumed the deep rod colour of alkaline phenolphthalein, whilst a colourless precipitate of free phenolphthalein separated out. At the same time the solution is found to have beconii' strongly alkaline. All these facts are capable of explanation by the ([uinone theory thus : — Assuming that free phenolphthalein has the usual lactone formula < > C„H. The lirst action of alkalies is to produce tlir rcil qiiincine salt ,COOKi c„h/ .-. On the addition of a furtlier i|uantity of alkali, the elfnionts of potassium (or s(iiiiuin) hydroxide are taken U]), giving rise to the colourless compound PVRONINK, DYESTUFFS. / CfiH / OH COOK "^OK / \oHor(OK) If, now, the cooled alkaline solution is neutralised with acetic acid, the follow- ing compound is produced : — ,COOK CeH / OH /-x KZ> OH This compound is unstable, and readily undergoes dehydration, the change apparently taking place in two directions, partly forming the red quinone salt and partly the colourless lactone. This view also explains the formation of the colourless alkyl derivatives (Herziy and Meijer) and the benzoyl derivative {Bislrz/jcki and Nenrki) mentioned above, since they would be derivatives of the colourless carbinol salt. The formula for phenolphthalemoxime given on p. 109 is that proposed by Hans Meyer {loc. rit.), who considers that phenolphthalem in coloured alkaline solutions has a symmetrical constitution COC,jHjOK CoHa \COC„HjOK whereas in neutral or colourless alkaline solutions it has the usual lactone form. The change from the lactone to the diketone form corresponds, he considers, with that of the unsaturated phthalides into diketohydrindene derivatives, and the reverse change with the intramolecular rearrangement of benzilic acid. CHAPTER XVI. ACRIDINE DYESTUFFS. To this group belong a few technically iiupuitant dyestufls, which are aniido- derivatives of phenylacridine and of acridiue (phenylacridine). (acridine). Mention has already been made of a dyestuft" of this group — Cliri/naniline — which was discovered by Nicholson in the mother liquors of Jfagenta prepared by the arsenic acid method. This substance is a dianiidophenylacridine of the constitution (Fischer and Korner, Ber., 1884, xvii. 203) N /\ \y NH., and its mode of formation is given on p. 88. The impure product occurs in commerce under the name of Phosphine, a yellow basic dyestuff which is largely used for the dycini; of leatlicr. In 1887 Rudolph (E.P. 9614^'') discovered other dycstuffs of this group, which are prepared by the condensation of an aldehyde with a ;/i-diamine, elimination of ammonia from the condensation product, and subsequent oxidation. An instance may be given in lienzoflavine [O] N which is prepared in the following way : — ACRIDINE DYKSTUFFS. 113 (1) Beuzaldehyde is condensed with ??j-toluylenediamine to form tetraamido- ditolylphenylmethane /NH, /NH., CeHjCHO + ; " -^ C.H5CH/ H.iC6lL,(CH3)< \CeH2(CH3)< \nh„ ^NH, (tetraamidoditolylphenylmethane). (2) When this is treated with hydrochloric acid, ammonia is split off and dihydrodiamidodimethylphenylacridine formed NH /^ /\ /\ /\ ,/\ \/ \/ \/ \/ \/' V^ CH CH I I (dihydrodiamidodimethylphenylaoridine). (3) The dyestiift' is then formed from this on oxidation N _ NTT ^^^/l^/^NH C„H5 (Benzoflavine). As a basic dyestiiff Benzoflavine finds considerable application in the dyeing of wool, silk, and cotton (tannin mordant), yellow. Similar dyestufls are : — Acridine yellow [L], from formaldehyde + /);.-toluylenediamine N C I H Acridine orange [L], from formaldehj'de + j«-amidodimethylaniline N {CH.,\-N('^/\\^-s{cii,),.nci c I H and Acridine orange R extra [L], from benzaldehyde + ;y(-amidodimethylaniline N (CH3).,N|A'^|^|^N(CH,),. HCl I CHAl'TEE XVII. OXYKETONE DYESTUFFS. The dyestuffs of this group contain a lien/.ene ring in which two ortho-hydroxy- groups are in the ortiio-position to a carbonvl group. They are, tlierefore, mordant dyestuffs forming coloured lakes with various metallic oxides, which are characterised by possessing remarkable fastness to both light and washing. Although the most important dyestuft' of this group is Alizarine, yet there are a few other dyoslutt's, not derivatives of anthraquinone, which are classed with Alizarine owing to the many properties they have in common witli it. To these belong : — Alir.arine yelloio C [li], wliich is prepared by the action of acetic acid and zinc chloride on pyrogallic acid, and has the formula OH CO CH,, Alizarine yellow A [B], from benz I 0/ The analogy in behaviour between cliloranilic acid, chloroxj'naphthalinic acid, and Alizarine, and the fact already' mentioned, that this latter substance gave anthracene on dry distillation with zinc Just, led Graebe and Liebermann 1 I 6 SYNTHETIC DYESTITFFS. {Ber., 1868, i. 49) to the assuniption lliat Alizarine was a dioxyantliraquinone and purpiuiiie a tiioxyautliiaciuinoiie I OH OH CioHjCl-l O. C,^,{ O o. OH > lo/ (cliloranilic acid). (cliloroxyiiaplitlialinic acid). (oxynaphtlioiininono). OH OH OH C,jH, ' C„H , OH OH O, (Alizarine). (Purpurine). ,o> These formula; were subsequently modified by the discover}' of Zincke and Fittig that anthraquinone was a diketono of the formula CO, C,;H/ \C„H, ^CO^ Continniny; their investigations, Gracbc and Lieberniann found tliat tiie corapoiuid previously prepared by Laurent by the direct oxidation of anthracene was identical «ith anthraquinone. In order to convert this into a dioxy- derivativc, they transformed it first into a dibromo-derivative, and then, by fusing with potash, produced a dioxyanthraquinone identical with the Alizarine from the madder root. Tliis, the first synthetic preparation of a natural dyestufl", was apjilied on tiic technical scale by the Badische Aniline and Soda Fabrik, but from the fn-st considerable difficulty was experienced in ]]reparing sufficient pure anthracene for the purpose. It was soon found, however, that Alizarine could be much more readily prepared from anthraquinone monos\dphonic acid. Some time previously Graebe and Licbermann had attempted, but without success, to prepare sulphonic acids of aiitiiraquinone by sidphonation, and it was first pointed out by Caro that on treating anthraquinone with sulphuric acid at 200° a sulphonic acid was formed, which, on fusion with potash, yielded Alizarine. Practically at the same moment the iilentical reaction was discovered by W. H. I'erkin in England. The ))atent application of Caro, (Jraebe, and Licbermann bears the date 25th June I8G9 ; that of W. H. Perkin, 26th .lunp 18G9. Another method for tlie preparation of anthraquinone disulphonic acid was again discovered, practically simultaneously, by Graebe and Lieberniann {Ann., 1871, clx. 137) and by W. H. Perkin {Ann., 1871, clviii. 319), and patented by the latter on 17th November 1869. This method consists in treating dicldoro- or dibroraoanthracene with sul- phuric acid, thus converting it into dichloro- or dibromoanthracene disulphonic acid, which, on further treatment witii sulphuric acid {Grarhc, IJuhermann, and Perkin), or by oxidation with MnOj {Perkin), is transformed into anthraquinone disulplionic acid. (1XYKETONK DYESiTUFFS. 11/ On fusion with potasli this disulphonic acid yields Isopiirpurine. The disulphonic acids of anthraquiuone are, however, at the present day prepared by direct sulphonation with sulphuric acid containing 40 per cent, of anhydride at 280-350° C. {Koch). In this way two sulphonic acids are formed CO CO CO (a-anthraquinone disulphonic acid). (;8-antliraquinone disulphonic acid). On fusion with caustic soda, the former yields Flavopurpurine ; the latter Iso- or Anthrapurpurine. When Alizarine was first prepared from anthraquinone sulphonic acid, it was thought that the disulphonic acid alone reacted. It was soon discovered, how- ever, that only the ;8-nionosulphonic acid is capable of yielding Alizarine with potash, the disulphonic acid being converted into trioxy-derivatives of anthra- quinone. The equation representing the formation of Alizarine is evidently as follows : — (sodium /3-anthraquinone monosulphonate). + Na.SO, + HoO + H., CO (sodium salt of Alizarine). The discovery of the true nature of the reaction ex[/Iaincd the loss of Alizarine experienced in the early days of the industry, which was evidently caused by the reduction of the anthraquiuone by nascent hydrogen. This is now obviated by the addition of sodium chlorate to the melt (Koch). The positions of the hydroxy! groups in Alizarine and Pnrpurine have been determined in the following waj' (Baei/er and Caro) : — (1) Phthalic anhydride on condensation with pyrocatechol in concentrated sulphuric acid solution yields Alizarine ,/\,C0\? H;-6,/\2-0H „„ 4 From this synthesis it follows that the two hydroxyl groups are in th position to one another. Il8 SYNTHETIC DYESTUFFS. It, however, does not determine their position with reference to the carbonyl groups, since the condensation might have taken place in the positions 4, 5 instead of 5, G. (2) Phthalic anhydride in the same way condenses with hjdroquinone to form Quinizarine OH CO OH I ^^ ^ _a. I I I I v '-'° ^ \y"\y'\y OH CO OH (Quinizarine). (3) Both Alizarine and Quinizarine yield Purpurine on oxidation. The only formulae in accordance with these facts are those given in the following equations : — (Quinizarine). Alizarine is insoluble in cold water, and is always met with in the form of a paste. This formerly consisted of 10 per cent, of Alizarine suspended in wat«r, but is now made almost exclusively of 20 per cent, strength. The price of 10 pet cent, paste in 1870 was 6s. to 7s. per lb., and in 1900 for 20 per cent, paste lOd. per lb. In this paste form Alizarine is sufficiently finely divided to be appreciably soluble in hot water : when once dry, liowever, it loses this jiroperty, and then is not well adapted for the purposes of dyeing and printing. For transhipment, Alizarine is frequently made in the form of a powder, which is dissolved in caustic soda and reprecipitatcd by hydrochloric acid by the dyer at its destination. It is also prepared in the form of a powder mi.xed witli starch : when placed in water the starch swells and the powder is converted into a thin i>aste suitable for the dyer. The mordant dyestufTs can be divided into two classes, (1) Polygenetic dyestuffs, (2) Monogenetic dyestuflfs, the former yielding diflTerent-coloured lakes with different mordants, the latter yielding the same coloured lake whatever the nature of the mordant employed. Alizarine is a polygenetic dyestuft" in the widest sense of the term, and gives the following series of colours with the mordants named : — OXYKETONE DYESTUFFS. 119 Magnesium, Calcium, Barium, Strontium, Aluminium, Chromium, Iron (ferrous), Irou (ferric). Copper, Lead, Tin (stannous). Tin (stannic), Mercury, . violet. purple-red. purple-red. red-violet. rose- red. brown-violet. black-violet. brown-black. brown-violet. purple-red. red-violet. violet. black-violet. iron, tin, and chromium lakes are In actual practice only the aluminium, emploj-ed. The methods of applying Alizarine to the fibres are dealt with on p. 293. Derivatives of Alizarine. — iViVro-derivatives. — Of the sis theoretically possible nitroalizarines, three only are known, and two have been thoroughly investigated. a.-Nitroalizarine lOH was originally prepared by Perkin by the action of nitric acid on diacetyl- alizarine. It is itself of no importance as a dyestufT, but on reduction is converted into a-amidoalizarine CO OH /^/\/" OH I I I I \/\/\/ CO NH, which is found in commerce under the names Alizarine (jarnet R [.M] and Alizarine cardinal [By]. P-Nitroalizarine — Alizarine orange CO OH OH /'no.^ was first prepared in 1874 by Strobel by treating material which had been dyed with Alizarine, with nitrous acid fumes. It can also be prepared by the direct nitration of Alizarine, and is a powerful dyestuff, forming orange lakes with alumina, and red-violet with iron salts. On reduction it is converted into [i-amidoalizarine — Alizarine-maroon [B] which forms red lakes with alumina and srev with iron. S V NTH KTIC I) V KSTU FKS. Ali::arine re'/ 8 [l^] is ali/arine monosulphonic acid, and is preijared by the tlirect STilpliuiiatiuii uf Alizarine. Its fornnila is CO OH CO SO,Na r, It is cliielly used for the dyeing of mordanted wool. Alkarine liliie [B]. — This important dyestutl' was first prepared by Pnid'liommc by heating /Siiitroalizarine (Alizarine orange) with glycerine and sulphuric acid. The determination of the constitution of this substance is due to Graebe (Ann., 1880, cci. 333), who found it to be an anthracjuinoline of the formula CO OH 000^ CO 1 N I I \/ Subsequently, the formation of a quinoline derivative in this reaction was confirmed by Skraup, who prepared quinoline by heating a mixture of aniline and nitrobenzene with glycerine and sulphuric acid. At the present day Alizarine blue is made in a similar way, viz., by heating a mixture of nitro- and amidoalizarine with glycerine and suljjhuric acid at 105° C. Alizarine blue is only feebly polygenetic, and gives blue lakes with most mordants. The most important is the Ciiromium lake. Alizarine blue 8 is the sodium bisulphite compound of Alizarine blue, and is the most usual form in which Alizarine blue is met with in counnerce. Ali:.arine green S [M] is the sodium bisulphite compound of the corre- sponding a-alizarine quinoline, and is prepared from a-aniidoalizarine. Its formula is CO OH OH + iiNaHSO, Isomerides of Alizarine. — Qintii.Mrine CO OH /\./\/\ 11)1 CO OH which is produced by the condensation of phllialic aniiydride with hydroquinone in the presence of sulphuric acid, is of no importance as a dyestutl' by itself, since, owing to the positions of the hydroxyl groups, it does not combine with mordants to form lakes. It is, however, converted into valuable acid dyestulFs on condensation with primary aromatic amines and siibseipient sulphonation. Such dyestuffs are Alizarine cyanine green and Alizarine pure blue. OXYKKTONR PYRSTUFFS. The^' are without mordant properties. Anthrarujine CO OH is formed, according to Schunck and Romer (Ber., 1878, xi. 1176), when »i-oxybenzoic acid is treated with sulphuric acid, or (Liebermann and Bock, Ber., 1878, xi. 1616) by oxidising authnicene-/3-disulphonic acid, and fusing the anthraquinone disulpiionic acid thus formed, with potash. It is the parent substance of the important blue acid wool dye, Alizarine saphirol R [By], which is probably diamidoauthrarufiue disulpiionic acid. Trioxyanthraquinones.— Pjwjwjmfi [B] CO OH I I I J°^ CO OH accompanies Alizarine in Madder, aud is formed synthetically either by the oxidation of Alizarine or of Quiuizarine. Its lakes witli mordants are very similar in shade to those formed from Alizarine. Anthracene brown [B] (Authragallol) is formed (SeuberHch, Ber., 1877, x. 38) on heating acid with sulphuric acid. Its chromium lake is brown. F/avojiurpuririe (Alizarine X [By]), (Alizarine GI or RG [B]) CO OH CO is prepared by fusing the a-disulphonic acid of anthraquinone PO3H ic acid and benzoic with potash. It is very similar in its properties to Alizarine. Alizarine SSS is the sulphonic acid (sodium salt), and is an important wool dye. Alizarine orange G [M] is the /3-nitro-derivative SYNTHKTIC PYKSTUKFS. From this, on troatiueiit with glycerine and sulphuric acid, the quinoline derivative AU-'iriw black P [M] is produced The bisulphite compound is Alizarine black S [M]. Isoiiurpurine (Alizarine GD [M]), (Alizarine RX [M]), (Aliziirine SX extra [Bj]) CO OH O^-^I^I^^H CO is prepared by the fusion of the /3-disulphonic acid of anthraquinone CO so^/^l^'^so^ CO with caustic soda. It is similar in its properties to the other members of this group. As a wool dye it is used in the form of its sulphonic acid, the sodium salt of which is Aliziirine SS. TetraoxyanthraquinoneS- — In 1890 Bohu {Ber., xxiii. 3739) made the im- portant iliscovery that by the action of fuming sulphuric acid on anthraquinone and anthra- the quinone ring in each case being the chroniophore of the dyestuff. This group may be divided into tlie following classes, which clearly show their relationship to one another: — Tj-pical Dyestuff. N (1) Tndophenols (2) Thiazines (3) Oxazines (Methylene blue). \/Y''^'^N(CH3),C1 (Meldola's blue). DIPHFINYLAMINE DYESTTJFFS. 125 Structure. N I I I I \y \/\ Typical Dyestuff. N I I II (Phenylene blue (base)). N I I I I N ■I I I N (Neutral violet (base)).i NCCHjl.Cl (Neutral lilue). (4) Indamines (5) The azine dyestufFs, com- prising : — (a) The Eurhodiiies . (h) Aposafranines ('_■) Safraniues (rf) The Iiidulines and Nigrosines. R. = benzene or naphthalene ring, and sometimes an aliphatic hydrocarbon radicle. The Aposafranines and the Safranines are placed in separate classes for the sake of convenience. They do not differ in structure. More recent investigations (Kehrniann, Ber., 1899, 2601 ; see also Green, Ber., 1S99, 3155) seem to show that the Oxazines and Thiazines probably possess a formula similar to the Eurhodines and Safranines (see later), in which the salt- formation takes place by the passage of dyad oxygen into tetrad oxygen, and of dyad sulphur into tetrad sulphur. Thus to the hydrochloride of Meldola's blue is given the formula CS.:/^/ \^CH3 ^nh:.hci. I I I I instead of O I 01 ^N(CH3), N(CH3),C1 and to the hydrochloride of Methylene blue, the formula N (CH,)^, instead of N(CH3: (CH.^)oN\ •N(CH3).,C1 For the oithoquiuone fonnulae of these substances, see p. 137. I 26 SYNTHETIC DYESTUFFS. Tlie experimental evidence upon which these formula! are based is, however, at present of so indefinite a nature that in the ensuing pages the older formula> liave been adopted. There seems, however, to be little doubt that many of the reactions of these compounds are best explained by the newer formula. (1) The Indophenols. As will be seen from the foregoing Uible, the Indamiuei and Indophenols are very similar in structure, the only difference being that in the Indophenols, oxygen replaces the group = NH of the ludamines. N ST III, . . , \/' \/\o '^ "^^NH (An Indophenol). (An Indamhie). Owing to the fact that the ludamines are closely related to the Eurhodines and the Safranines, and occur as intermediate products in their preparation, they will be dealt wiih later togetiier with these dyestufTs. The Indophenols are made by the oxidation of a mixture of a /)-diamiue and a phenol, or by the interaction of nitrosodimothylaniline with phenols. The only technically important Indophenol is prepared from nitroso- dimethylauiline and a-naphthol /\ /\ NO H^ < > If I I irTT.J I 1 J I I I I +H3O (nitrosodimethylaniline), (a-naphthol), (Indophenol), and also by the oxidation of a mixture of ;*-amidodimethylanilino and a naphthol {Kuchlin and Witt). It is a dark brown powder insoluble in water, and is applied to the fibre in precisely the same way as Indigo (see p. 291); that is to say, on reduction it yields Indophenol ichite {cs^yjsfsj '\/'oH which in alkaline solution possesses affinity for the fibres, upon which it can be reoxidised to the blue on exposure to the air. (2) Thiazines, The first dyestuflf of this series was discovered by Ch. Lauth in 1876 (Compt. tauth's violet, by oxidising, with ferric chloride, a solution of /j-pheuylenediamine con- taining sulphuretted hydrogen. Its constitution and that of other members of this series has been determined by Bernth.sen (Ber., 1883, xvi. 1025, 2896; 1884, xvii. 611, 2854, 2857, 2860 ; and Ann., 1885, ccxxx. 73) ni the following way: — DIPHENYLAMINE DYE8TUFFS. Tlie action of sulphur on dijihenylauiine j'ields thiodiphenylamine I I J J S which, on nitration, yields a p-dinitro-derivative NH ■Ill o„n' 'NOo and this iu its turn is transformed, on reduction, into di-jj-amidothiodiphenyl- aniine NH h.;nI I .1 Inh, s which is the le>ico-base of Lauth's violet, yielding this dyestuff on oxidation and conversion into the hydrochloride. Consequently Lauth's violet has the constitution N It 1 is now of little importance, and has been replaced by the most important member of this series — Mi'thylene blue B [B] (CH3), N(CH.;),C1 This dyestuff was first prepared by Oaro in 1876, who applied Lauth's reaction to asy7)i-dimethyl-p-phenylenediamine, and who, in conjunction with the Badische Aniline and Soda Fabrik, prepared it technically (D.P. 188G") by oxidising amidodimethylaniline, prepared from nitrosodimethylaniline, in the presence of liydrogen sulphide. At the present time Methylene blue is produced solely by the " thiosulphate process," which consists iu oxidising diraethyl-ji-phenylenediaraine and dimethyl- aniline in the presence of sodium thiosulphate and zinc chloride. The course of this reaction may be represented by the following equations : — (1) /NH., I 1 + H.S.,0, + -> (CH.,),N'' ' {a6'^/rt-dimethyl-^>phenylenediamine). I I (CH3)2n/^/Vs03H (a thiosulphonic acid). H2O ' This dyestuff was never manufactured to any extent on the large scale, the small yield of it (scarcely 20 per cent. ) rendering its production too costly. .SVNTHETK DYKSTIFFS. (2) /\/^'^ (dimethylaniline). N 1^ 11.^ + vHjO (3) N I / so/ + HCl + O SOj > (CH,).^!^ ^ "s "^ ^'N(CH3).,C1 (Melliyleiie blue) Methylene blue is usually met with iu commerce iu the form of its ziuc chloride double salt, and is a most important dye for cotton, upon which it is fixed by the aid of tannin. It is not well adapted for the dyeing either of silk or wool. Other dyestuffs of this series are : — Gentianine [G], from />-phenylenediamine and //-amidodimethylaniline N I I. I I (CHj)^!-' Methylene green [M], fruni .Methylene blue and nitric acid NO; N I I I I (CH3).,N/'^^^\^^N{CH.,).,C1 Thionine blue G [M] 'rhiocannine K [C] fill (CH3),N/ V Y ^N'(CH3)C,.H,.C1 N '\t SO I S03Na.C^Hj.CHj.(C.jH5)N/ ^^ g ^N(C..JH5)CH.C,;H, Toluidine blue O [H] (CHjXiN^ \/ Y ^H^Cl DIPHKNYLAMINE DYESTUFFS. New methylene blue K [UJ I I I I . Brilliant alizarine blue GR [By] SO,Na ^\' N I I I J I 1 129 (3) Oxazines. The first dyestuff of this group was discovered by Meldola in 1879, who prepared it by condensing ^-naphthol with uitrosodimethylaniline chloride in glacial acetic acid solution. Its constitution is represented by the formula O - >-N(CH3)„Cl (Meldola's blue). It also occurs in commerce under the names Fast blue, New blue R [C], Cotton blue R [B], etc. The dyestuff is now formed by using alcohol as a solvent instead of glacial acetic acid, and it is advisable to keep the proportion of y8-naphthol and uitroso- dimethylaniline — 1 mol. ^-naphthol : 2 mols. of the latter. {Private cominuniration, R. Meldola.) It is largely used for the dyeing of tannined cotton. Other dyestuffs of this series are : — Capri blue GN [By] — niti-osodimethylaniline + dimethyl-ju-amidocresol (CH,),N- - O ■ N(CH,)X1 Gallocyanine DH [DH] — uitrosodimethylaniline + gallic acid CO N I I I OH'v OH O N(CH3), I (base). .SYNTHETIf DYKSTUFFS. Delphin blue [S] — Gallocvaiiiiie + auiliue aud sulphonation NH,OS-C,H,HN N °^ OhV ^N(CH,),OH (ammonium salt). Prune pure [S] — nitrosodimethylauiline + meth^-l ester of gallic acid CH,OOC N fill 0H/'~^^^'^N(CH3).,C1 (iallaiuine blue [By] — nitrosodimetlij'laniline + gallaminic acid (gallamide) NHjOC N I I I I. (base). Coreine KR [DH] — nitrosodielliylanilinc + gallamide HJIOC N " /\/\^\ I I I I his blue [B] — -nitrosoresorcinol + resorcniol and broniination N Br O Br New metliylene blue GG [C] — dimethylamine + Meldola's blue and oxidation /-\ N I I I I Nile blue A [B] -nitros()diethyl-»'-aniidoplicnol + a-naiihthylaniinc I I I I + (SOJi H^/\/ Y^^ ^n(c.;h.)., Nile blue 2B [B] — nitrosodiethyl-?)i-aiiiidophenol + heuzyl-a-nii|ilitliylaniine C„B5Ca,.HN/ V V ^'^N(C,H,)„C1 T)TPHENyLAMINE DYESTUFFS. I3I Muscarine [DH] — nitrosodimethylaniline + 2:7 dioxynaphthalene I I I I Alizarine green G [D] — (8-naphthoquinone sulphonio acid + 1 -amido- 2 uaphthol-6-sulphonic acid I J J I o OH " Alizarine green B [D] — yS-naphthoquinone sulplionic acid + 2 - amido- l-naphthol-4-8ulphonic acid SO,H O OH Fast black [L] — nitrosodimethylaniline + »i-oxydiphenylamine C1(CH3)3N^ ^ X ^ V ^ ^N(CH3)C1, (4) Indamines. The dyestu£Es of this group belong to the oldest of the artificial colouring matters, some of them having been formed by Riinge and Perkin in their experiments on the oxidation of aniline. They are mainly interesting as intermediate products in the manufacture of the Eurhodines and Safranines. Tlie simplest Indamine is Plienylene blue N I I I I aN^x, y^NH (base), which can be prepared by the oxidation of a mixture of j>plienylenedianiine and aniline NH, N II +11 + O, -> I I I I + 2H,0 h:,ii/\/' \/\nh, h,n/^-^ \/'^.nh Indamines can also be prepared by replacing the ^-phenylenediamine in the above reaction by such bodies as nitrosodimethylaniline N(CH,), (1) ^NO (4) 1^2 SYXIHKTIC n\HSTrKKS. ami (liclilui'i|iiiiioiuiijiiIe /NCI c,.,h/ 1 ^NCl wliich yield p-diamines on reduction. The dyestuffs of this group are not of any techuical importance. Two, however, possess theoretical interest owin^' to their close relationship to the Eiirhodines and Safranines. Bimhcliedler's ijreim — din)Ctiiyl-/'iihenylcncdiamine + diniethylaniline N and Tuluijlene blue (Witt) — dimethyl-^>phenylenedianiine + w-toluylenediauiine which is of considerable theoretical importance, since, on heating witli water, it passes into the Eurhodine, Neutral red. Similarly, ;)-phenylenediiimine and w'-toluylonediamino yield the Indamine which, on boiling with water, gives the Eurhodine, Toluylene red (see liclow). (5) The Azine Group. The Azine dyostuils maj' be regarded as derivatives of phenazine N N I I ! I or fill N N and comprise (a) the Eurhodines, {!>) the .\pusafranincs, (-•) the Safranines, ((/) the Induliiics and Nigrosines. (a) The Eurhodines. ^Tliese dyestulls arc amido-derivativos of phena/.ine, and their constitution has been determined in the following way : — Phenazine was obtained by Merz and Ris by condensing pyrocatechul witli 'i-phenvlcncdiainiiip N , ' - OH HN ,^/\/\ N 'pyrocatechol). (o-phenylenoiiiaininc). (phenazine). DIPHENYLAMINE DYESTUFFS. I 33 In tlie same way they prepared methylphenazine N i I 1 Y^^' N from pyrocatechol and o-toluylenediamine. Now the Toluylene red mentioned above was found by Bernthsen and Schweitzer (Ann., 1886, ccxxsvi. 332) to give the same methylphenazine on eliminating its two amido-groups. It must therefore be a diamidomethylphenazine of the formula N N and its formation from the Indamine can be represented by the following scheme: — NH NH HjN NH (The Indamine (leuco-compound)). (Toluylene red (leuco-compouud)). I +0 N „J I I \Z^ + H,0 N (Toluylene red (base)). In the same way the Neutral veil [( '], mentioned above as having been prepared from Toluylene blue, has the formula (base) N /\/ \/\.CH I I I r ' (CH,),N'\y\ /\/-NH, N The only other Eurhodine of importance is Neutral violet [C], prepared by the oxidation of a mixture of ^)-amidi)dimethylaniline and ?;i-phenylenedianiino. It has the formula (base) N /\/l\X\ (CH,),N'\^-k I -\/'nH„ N The Aposafranines, Safranines, and Indulines differ from the Eiirhodines in that one of the nitrogen atoms of the phenazine molecule is combined with another benzene or naphthalene ring. The Aposafranines are monoaniido-derivatives or monohydroxy-derivatives. The Safranines are diamido- and the Indulines tri- or tetraamido-derivatives of the phenazine so substituted. 134 SYNTHF.Tir DYESTrFFS. Constitution and History of the Aposafranines and Safranines. Substances belonging to tlie group of the Safranines are among the oldest of the coal-tar colouring mattere, since Mauveme, the first artificial dyesiuflT prepared (Perkin, Proc. U.S., xxxv. 717), belongs to this group. From the mother liquors from Mauveiue, Perkin (Chein. Netcs, 1861, iii. 348) isolated a red dyestuf!', to which he gave the name Pink (Chem. Ketcs, 1869, xix. ISI), and which he suggested {il>i'l., 1870, xxii. 80) might be identical with Safrauine. The first technical production of Safranine under this name was carried out under the French patents' of Felix Duprej' in 18G5, but without success; and it was not until IS6S that Lotz, of Basle, produced it in any quantity under the name of Safllorsurrogat. The first technical production of Safranine in Germany was carried out by Caro, who at first employed the Duprey method, but subsequently adopted that discovered by Nietzki, which consisted in heating ^-toluidine-azo-o-toluidine and o-toluidine-azo-o-toluidiue in acetic acid solution together with a small qiiantity of nitric acid, on the water-bath. In 1877 Witt (Bet:, x. 874) published a constitutional formula for Safranine, based upon the fact that it could be prepared by heating amidoazotoluene with o-toluidiue in alcoholic solution. The equation representing the reaction he gave as follows : — 1 H N[1]C,B,[L']CH3 H-J) NHj (amidoazotoluene). ("-toluidine). C f[2]CH •• n[i]N 5,;hJ (3) li4) (1) N N[l]C,H,li]CH, CK, (Safranine). And a similar azo-foi-mula for this substance was proposed in 1879 bv Perkin {J.C.S., 1879, xxxv. 717). The incorrectness of these formulae was shown by the discovery by Witt in 1878 of phenosafrauiue, which he prepared by the oxidation of a mixture of ju-phenylenediamine and aniline ; and it was subsequently found that the Safranines are formed by the joint oxidation of 1 mol. of a yi-iliamine with 2 uiols. of a monamine. The first insight into the true constitution of the Safranines was afforded by Nietzki, who prepared a Safranine by the oxidation of equal molecules of diethyl-^j-phenylenediamine and aniline, whereby the existence in Safranine ' The methods consisted in (1) oxidising Mauveine with barium peroxide ; (2) heating Aniline in acetic acid solution with lead nitrate. DIPHENYLAMINE DYESTUFFS. I 35 of two monoamine radicles with their benzene rings attached to nitrogen became probable. Nietzki also prepared a tetraethyl safranine which supplied further evidence of the presence of two amido-groups in the safranine molecule. He then gave this dyestuff the following formula, in which a relationship to p-rosaniline is indicated : — >N< I >C< I /\ H CI H CI (Safranine hydrochloride). (Rosaniline hydrochloride). Leuco-safranine (prepared from Safranine on reduction) he considered to be triamidotriphenylamine /C^H^NHo NCsH.NH., The incorrectness of these formulse soon became apparent, however, when it was found that pheuosafranine had the empirical formula CjgHj^N^HCl, or two atoms of hydrogen less than that assumed by Nietzki. The ne.\t step in the solution of this problem was taken by Witt (Ber., 1SS5, xviii. 1119), who found that by the condensation of amidoazotoluene (from ^-toluidine) with a-naphthylamine hydrochloride a yellow compiound, closely allied to the Safranines, was formed, and not a complicated Induliiie dyestuff, such as was produced from other primary amines. He further found that similar compounds were also formed when other amidoazo-compounds containing the amido-group in the OJ'^/to-position to the azo-group were heated with a-naphthylamine. 'i'he compounds so produced Witt called Eurhodines, and for the compound formed from amidoazotoluene and a-naphthylamine he proposed the fornuila CH.f' About this time the work of Merz and Ris on phenaziue, already- referred to, was published, and therefrom resulted the elucidation of the constitution of Toluylene red by Bernthsen and Schweitzer. These facts, together with the discovery of the close relationship between the Indamines and Safranine on the one hand, and on the other the analogy between Tolu\ lene red and Safranine, led Bernthsen (Ber., 1886, xix. 2691) to the assumption that the leuco- compound of pheuosafranine was formed by the interaction of equal molecules of ^-diamidodiphenylamine and aniline, and that its formation could be represented by the following equation : — NH NH 4H 136 SYNTHETIC DVKSTUFFS. For the dyestuff whicli is pre|)ared by the oxidation of the leuco-base and subsequent conversion into tiie salt, he proposed two formula) : — K and ^-■''V/\!/\/™^ r, \/ II. Formula I. does not give the two amido-groups which are assumed to be present in Safranine, aud therefore formula II. alone suffices to explain its constitutiuu. Against this formula Nietzki (Ber., 1886, xix. 3164) argued that it did not explain the existence of two isomeric dimethj-lsafranines, which he had prepared, aud found to be diflferent by a close examination of their crystalline form and solubility. Berntlisen (Bur., 1887, xx. 179) examined these dimethylsafranines, and also came to the conclusion that they were diirereiit. He therefore, with Xietzki, adopted an asymmetrical formula proposed by Witt {Ber., 1886, xii. 3121): — N N 01 [Nsi f 1 A A NH., (Witt's formula). (Bernthsen's formula). Tiie formation of the Safranine of this formula from di-^-amidodipheuylamine and aniline, Witt explained by the following equation : — I I (aniline), (/)-diamidodiphenylamine). (leucosafranine). For some lime tlie asymmetric formula was accepted as correct, until Korner and Schraube showed that it had Ijeen founded ii\Km an error, and that the two isomeric dimethylsafranines of Xietzki were in rcalitj* identical. This led to the readoption of the symmetrical forniula, wiiich has since been verified by a number of experimental facts. In 1888 Witt (Bei:, xxi. 719) published some experiments which clearly indicate the close relationship between the Eurbodines aud the Safranines. diphenylami:ne dyestuffs. 137 If uitrosodimethvlauiline is condensed with jB-naphthylamine, dinietliyl- phenyluaphtheurhodine is prodviced according to the equation NO NH, N /-\ 3 11+2 111-^ SaO +11+2 I I I I (a Eurhodine). If, however, the ;8-naphthylamine is replaced by a secondary base derived from it, a Safrauine is produced according to the equation NO 3 I 1 +2 1 ! I + HCl NH., N N(CH3), ■ N 11 I ,\ci R (a Safranine). Other investigations on the constitution of Safranine have more recently been published by Kehruiann and Messinger (i?e?-., 1891, xxiv. 584, 2167), Kehrmanu {ihifJ., 1894, xxvii. 3349), Jaubert (ibid., 1895, xxviii. 270, 508, 1581; 1896, xxix. 414), Nietzki {ihid., 1895, xxviii. 1354; 1896, xxix. 1442), 0. Fischer and Hepp {ibid., 1893, xxvi. 1195, 1655; 1895, xxviii. 2283: 1896, xxix. 361 ; Ann., 1895, cclxx.xvi. 211), and 0. Fischer {Ber., 1896, xxix. 1870). The main object of these researches was to determine which of the two following formulaj represented the constitution of Safranine chloride : — N N N ILN*. J ' Ntt, .«■ &,»!. J. I NHL, J. ■ i A ^■^-' - " ^V^ ' ciaHN^^Y ,/\ .^ I CsHj CI CgHs CI CeHs One of the chief points which had to be explained was the following : — Safranine readily yields a diazo-salt with nitrous acid, which, on boiling with alcohol, gives Aposafraniue, a substance which does not react with nitrous acid under ordinary conditions, and therefore presumably does not contain a primary amido-group. This behaviour can only be explained on the assumption that formula II. represents the constitution of Safranine N KN-^V'^^^^ CsHj CbH,. (Safranine). (Aposai'ranine). 138 SYNTHETIC DYESTUFFS. Similar behaviour is exhibited by the corresponding: hydroxy! derivatives Aposafranole and Safranole N N I I I bH I I I I I (Safrauole). ( Aposafranole). In Safranole onh' one hydroxyl {iroiip can 1* detected, and in Aposafranole none at all. 0. Fischer and Hepp, however, prepared certain chlorine derivatives from Aposafranole and Safranole, the formation of which can only be explained on the assumption that tliose substances have the orthoquinoid structure represented by formula I. Kehrmaun also showed that Apusafranine could be diazolised by dissolving it in concentrated sulphuric acid, and treating the green solution tims formed with nitrous acid. On boiling this di;izo salt with alcohol ho obtained an iizonium base — ]ihenyl- phenazonium N or I I I I \y\y\y' N /\ CbH, oh This behaviour of Aposafranine seems to indicate that at :iny rate in con- centrated sulphuric acid solution it contains a primary amido-group, and that therefore, under these conditions, it possesses an orthoquinone structure ; and these considerations, taken in conjunction with those alreaily mentioned, would seem to show that Safranine can react either as a paj-a- or as an ortho- quinone derivative, according to the nature of the reaction involved. In the caseof diamidoeurhodines, both amido-groups arc readil3'diazotisable,and therefore there is no reason to assume a yja/'aquiuone structure; but, as Kehrmann has shown by the following experiments, they also appear to react in two forms. liosinduline is formed from phonyl"-phenylcncdiaminc and oxynaphtho- quiiioneiniide <:> =0 h:,n- N HN^^ I y HN \/V^^ C,H, I CfiH, (Kosinduline). If the phenyl-o-phenylenediamine is replaced by o-phenylenediamine, a Kurhodine is formed DIPHKNYLAMINE DYESTUFFS. I 39 From these experiments, therefore, the Kurhodines would appear to be ^)-quinoiie derivatives. Kehrmann and Messinger attempted to decide this question by methylating a Eurhodole of the formula N _. \/|\/\ I I I I The methyl ether formed would then have either the formula I I and, if the latter, it would be identical with the Eurhodine prepared by the con- densation of oxynaphthoquiuone with methyl-p-phenylenediamine \ = H.,N| ■ I. I— OH + HnI J "* Qy \/ I -^ CH, CH3 Kehrmann and Messinger found that two methyl ethers are formed by the methylation of the above eurhodole, and one of them is identical with the methyleurhodole obtained by the condensation given above. Therefore the Eurhodines, like the Safranines, appear to be desmotropic substances. (b) The Aposafranines. These dyestuffs are, as already mentioned, monoamido- and monohydroxy- derivatives of phenyl- or naphthylphenazine. Many of tliem ai-e prepared by melting together a mixture of an araidoazo- compound with a primary base and its salt, and an explanation of this process will be given under the head of the Indulines. The two following dyestuffs belong to this group : — Azocarmine G [B] is prepared by fusing aniline-azo-a-naphthylamine + aniline -I- aniline hydrochloride and subsequently sulphonating with fuming sulphuric acid. It is the sodium salt of phenylrosinduline disulphonic acid ,/\ I I N I I I J I (Phenylrosinduline). 140 SYNTHETIC nVKSTrFFS. A-Mrariiiiw Vt [B] is the sodiiiin salt of plicnylrosiiiduliiie trisulphonic acid, made by tiie furtlior treatment of plienylrosinduliiie with fuming sulphuric acid. On treating' tiiis trisulphonic acid with water at 160-180°, it is converted into liosindtdine 2G [K], which is the sodium salt of a rosindone monosulphonic acid I J N V I (Rosindone). Another sulphonic acid (sodium salt), namely, Wmndnline G [K] \/\/\Y\ I I I I It I is prc[)ared by heating phcnylrosinduline-G-(naph.)-monosulphouic acid with water under pressure. These dyestufl's are important acid wool dyes. Neutral blue [C] — nitrosodimethylaniline + phenyl-/3-naphthylamine — is ,^ N I I I .1 ci(CH3)..jr^"' and its derivatives, Bade blw K [DH] — nitrosodimethylaniline + 2 : 7-ditolyl- naphthylonediamine NH.C,^4.CH3 N ( I I I .1 J C1(CH,).,N and Azine I J +2 i I I I , + 2H2O N(CH3),, pl^ ■N-ti-i'6^.5 N(CH3)., (^^■■■'■"M ^T JMO„±l, (Indazine (base)), a blue tannined cotton dyestuff. (3) By melting certain amidoazo-compounds with primary bases (see p. 146). An example of this method is MilUni/ hhie [K] (Naphthyl blue) — aniliue- azo-a-naphthylamine + a-naphthylamine HCl + aniline (Sulphonated.) TsracM, This reaction can be explained by assuming the decomposition of tiie amidoazo- compound into bases suitable for the production of Safranines. Milling blue is a wool dye, and is affixed to the fibre by the aid of chromium salts. 142 SYNTHETIC DYESTUFFS. The most important ineiaber of this group is Satranhtf T [B] CH. N OH It IS made by the oxidation of ecjual molecules of //-toluylenedianiiue and o-toluidine to the ludamine, which is converted into the Safranine by oxidation with aniline. It is also sometimes made from an aniline rich in o-toluidine (aniline oil for Safranine), and from the basic mixture known as I'-chappes, which distils over during the manufacture of Magenta. This basic mixture, which contains large quantities of o-toluidine, on treat- ment with nitrous acid forms the azo-compound /\ which is tii-st reduced to form o-toluidine and /(-toluylenedianiiue, and then these two bases are oxidised with aniline to form Safranine iCHs H2N -<3^NH, (Safranine (base)). Safranine is a basic dyestufT well adapted for dyeing cotton rod on a tannin nmrdant. It gives characteristic colorations with strong sulphuric acid, dissolving to form a green solution, which, on gradual dilution, passes through bine and violet to red. When treated with nitrous acid it yields a diazo-salt, which on combining with /^iiaphthol gives Indoine blue R [B|, an important dyestuff. dyeing both unmordanted and tannined cotton fast indigo shades of blue. Other dyestutl's of this group are : — /''<(.s/ neutral ciulet B [C] — nitrosodimethylaniline + diethyl-'/i-phenylene- diamine CUCH. 'ifHCH, CoH, dyeing taniiiued cotton a fast violet siiade DIPHENYLAMINR DYESTUFFS. 143 Methylene violet RRA, 3RA [iM] — oxidation of dimethyl-jj-phenylenediamine + iiniline N C1(CH.,),N ^'^ N I dyeing taunined cotton red-violet. Saf ratline MN — oxidation of dimethyl-/;-plienylenediamine + aniline + o- or ;j-toluidine ; for example : — N I I I I CH, C1(CH,),N ^^ iJ ^ ^NHj I also producing red-violet shades on tannined cotton. Girujie [DH] — nitrosodimethylaniline + a mixture of m- and ^'-xylidine ; for example : — N CH.5 I I I I dyeing tannined cotton red-violet. Amethyst violet [K] — oxidation of diethyl-;)-phenylenediamine + diethylaniHne + aniline N /^/■\/\ \ 1 ,1 I ck dyeing silk violet with red fluorescence. Mauve'ine — oxidation of aniline containing toluidine ; for example : — N . .^ J I I CfiH,(CH,) This dyestuflf is most interesting from an historical point of view, since it was the first artificial dyestuflf prepared. 144 SYNTHETIC DYESTUFFS. Ill 1856 I'erkin {Zeit>:chi: f. Cli., 1861, 700) attempted to jirepare i)iiinii)e by tiie oxidation of allyltoluidiiie 2C,iH,(CH,)NH.C3H,H O, -: C.,,jH.,^N.,0, + H.,0 but obtained instead a dark-coloured precipitate. A similar substance was also obtained by the action of potassium bicliroinato on aniline sulphate, which, on closer investigation, yielded a violet dycstufV, which I'erkin patented in England on 26th August 1856, and proceeded to manufacture on the large scale, under the name of Mauve. iMauveine is now little used. Until quite recently it was employed for printing the mauve penny postage stamps of the last reign. Tiie constitution of Mauvcine is shown by the synthesis of phenomauveine from nitrosoaniline and diphenyl-H(-phenylenediamine (Fischer and IJepi') 3 I ! + 2 I I - O . HCl HsN/^^^H HN ^ NH.CH. NHo I 2H.,0 NCH.HCl C,.H., ( i'henomauveine). Mi'taphenyleiie blue B [C] — nitrosodimethylanilino + di-y-tolyl-?»-plienylene- i diamine N r-r"^ I I 1 N C,H,N ^"\/Y^'"^N{CH,),, dyes taniiined cotton Indigo blue. Xa/ilithaxine blue [D] [^I] — nitrosodimetiiylaniline + /i-dinaphthyl - m- plu'iiylenediamine disulphnnic acid N y C,„H,N ^ ^ ^ ^N(CH,), (base) is a blue acid wool dye. M(i(/ ^-y =NTi J\ / \ -NH.C,;H, HN^ ^/ HN- -^ (hydrazone form). (anilidonaphthoquinonediiniide). Other instances of a molecular transformation of this kind are known. Thus, benzene-azo-a-naphthol, on heating for eight hours with glacial acetic acid, is converted into 2-anilidonaplithoquinone together with a small quantity of 2-anilidonaphthoquinone-l-imide N - NHCfiH. benzene-azo-o-naphthol (hydrazone (2-anilidonaplithoquinone- (2-aniIidonajihtlio- (azo-form). form). 1-imide). quinone). (3) The formation of the phenylrosinduline then takes place as follows : — /\ I I jjig /\ . A J-NH + V- ■ __^ Y Y- _ +2NH3 I NH.VCfiH, " i YnH and (2 mols. aniline), /\ /\ ' ' -u:h ^ ^ I I I I + H,0 I ■ CeH,N^\-^Y^^ CeH, (Phenylrobiuduline). 148 SYXTHF.TIC DYKSTITFFS. If the above method of forming phenyl rosinduline be modified by heating benzeue-azo-a-na|ilithj-laniine with aniline and alcohol under pressure, the simplest rosinduline of the formula is formed ; and when this is heated with concentrated hydrochloric acid under pressure, tlie corresponding rosiiidone is produced .1 N I C,;H-, (Rosindone (see Iiofindnline 2G)), and the substance, on distillation with zinc dust, yields a-iiaphtliDphenaziue /\ I I N I I I I I (a uaphthophenazine). These facts, taken in conjunction with the synthesis of rosinduline by Kehrnianu and Messinger {Ber., 1891, xxiv. 587) from oxynaphthoquinoneimide and phenvlo-phenylenediamine \/\= O tt.N ^ and of rosindone from oxynaphthoquinono and phcnyl-o-phenylencdiamine f I N C,;H,i C,;H, clearly show that the rosindulincs are derivatives of 4 iiaphthoquinone-l-imide, and that the indulines are similar derivatives, containing further amido- or sub- stituted amido-groiips. niPHENYLAMINE DYKSTTJFFS. 1 49 Fast blues (spirit soluble). — Under this name a number of dyestuffs are found ill commerce distinguislied by the affix R or B, according to the nature of their shade. They are prepared by heating together amidoazobenzene and aniline hydro- chloride for a more or less prolonged period. The longer the heating is continued, the bluer is the dyestuff produced. For the most part they are used as pigments, but also find application in solutions of etiiyl tartaric acid, Isevulinic acid, or acetine (prepared by the action of acetic acid upon glycerine), for the purpose of printing upon cotton. Under these conditions the}' are known in commerce as Printing blue [A], Acetine blue [B], and Lrovuline blue [M], etc. Fast blues (aohMe). — These dyestuft's are the sodium salts of the sulphonic acids prepared by the sulphonation of the various brands of Fast blue (spirit soluble). They are used as acid dyes for the dyeing of silk and wool, and are also tannined cotton colours. Nigrosines from nitrobenzene. — Ifagenta is formed by the oxidation of aniline, toluidine, nitrobenzene, and nitrotoluene in the presence of iron and hydrochloric acid. Under precisely the same conditions Nigrosines are produced from aniline and pure nitrobenzene. This method of preparation was discovered by Stiideler in 1865, who employed 2 mols. of aniline hydrochloride and 1 mol. of nitrobenzene, and heated the mixture to 230°. V. Dechend and \Yichelhaus (Ber., 1875, viii. 1609) investigated this reaction, and found that by heating nitrobenzene and aniline hydrochloride together with a little iron chloride, at 210° in a sealed tube, a base, CjgHjjNj (?), was formed similar in properties to the Azodiphenyl blue prepared from amido- azobenzene and aniline hydrochloride. The same base is formed by heating together azoxybenzene and aniline hydrochloride in a sealed tube at 230°. Nig-POSineS from Nitrophenol.--The formation of these compounds is brought about by heating crude nitroplienol, prepared by the nitration of phenol, with aniline and aniline hydrochloride at 180-200°, until a test portion dis- solved in alcohol gives the required shade of colour. The Nigrosines (spirit soluble) so produced are converted into Nigrosines (soluble) by heating with fuming sulphuric acid at 80°. Aniline Black. Runge, in 183-1, and, later, Fritzsche (/. pr. Ohem., 1840, xx. 454) noticed that, by the oxidation of aniline salts with chromic acid, dark green and blue- black compounds were produced, and in 1843 Fritzsche (J. pr. Chem., 1843, xxviii. 202), by treating aniline hydrochloride with potassium chlorate, obtained a dark indigo blue substance containing 16 per cent, of chlorine. Perkin also, in 1856, obtained a dark-coloured precipitate by the oxidation of aniline sulphate (containing toluidine) with chromic acid, from which he extracted Mauveine (see p. 144). It was subsequently found that this substance could be obtained by the action of other oxidising agents upon aniline, and also by electrolysis (Goppels- riider). ISO SYNTHETIC DYESTUFFS. The fact that the empirical formula of Aniline black is (CgHjN)^ (Go/jpeUiudi'i; Kai/ser, and Nietzki), and that on energetic reduction it yields di-;Adiamidodiphenylaminc, would seem to show it to be a highlj' complex induline. Its constitution, however, has not yet been definitely determined. Mild reducing agents convert Aniline black into a leuco-compound, and when it is heated for several hours with fuming sulphuric acid it yields a sulphonic acid soluble in water {Nieizki). The action of sulphurous acid converts Aniline black into a green compound — Emeraldiue, which can be considered as an intermediate product in its production, since, on oxidation, it is reconverted into the black. Aniline black, except as a pigment, is not sold in the finished state, but is always produced upon the fibre. Owing to its fastness it is still one of the most important black dyestufTs, especially for the d^'eing of cotton. The analogous compound, prepared by i'iria from napbthylamine, known as Naphtlujlamine violet, is of no practical importance. CHAPTER XIX. QUINOXALINE DYESTUFFS. These dj'estuffs are derivatives of quiuoxaliue I I \? which was prepared by Hinsberg by treating opheiiylenediamine with glyoxal I IniHj i 0H;0 i. 11— N = CH (o-phenylenediaraine). (glyoxal). (quinoxaline). The only derivative of this substance which is at present of any technical importance as a dyestuff is Flatinduline [B] 11 11 I I /^\ X/OeHs CI which was prepared by C. Schraube (E.P. 18,37493, A.P. 543,78495) by the action of o-amidodiphenylamine on phenanthraquinone in glacial acetic acid solution. The commercial product is an orange-red powder, soluble in water, which dyes tannined cotton yellow. It is remarkable that this dyestuff contains no auxochrome group. CHAPTER XX. THIAZOL DYESTUFFS. These dyestuffs contain the thiazol ring /C — N'-' and are Jerivatives of delijdrothiotoluidine. The constitution of tliis substance lias been determined in the following way : — Merz and Weith {Ber., iv. 393) obtained thiotoluidine by the action of sulphur on j)-toluidine in the presence of lead oxide at 140° CH, /CHj (1) // ^NH., 2C6H.< + S.. -> S< " ^ H.JS \nH., (4) " \ ,NH., \, *<.. CeH,, Later, Jacobson {Ber., xxii. 333) and Gattermauu {Ber., xxii. 424 ; xxv. 1084) obtained a body containing 4 atoms of h3drogen less, which the}' prepared by heating j)-toluidine with sulphur, first for eighteen hours at 180-190°, and then for a furtlier six hours at 200-220°. This substance they termed dehydrothiotoluidine, and gave it the formula CHC.H, \C.C„H,NH., since, on treating it with nitrous acid and boiling with absolute alcohol, it was converted into benzenyl-3 : 4-amidothiccresol which Hess {Ber., xiv. 493) had prepared by the action of benzoyl chloride on 4-amidothiocresol, CH., C,H,,(NH.,)SH. The lower homologuc, ben/.enylamidothiophenol ;C.c^. has been prepared by Hofmann {Bur., xii. 2360; xiii. 1223), both by the action of sulphur on beuzauilide. CeHjCONHCcH, + S -> C^S./ ^C 0„^ + H,0 and by heating oamidothiophenol with benzoyl chloride. THIAZOL DYESTUFFS. I 53 Dehydrothiotoluidine is not a dyestuff, but if a higher temperature and more sulphur be employed in its preparation, a base is formed which, on sulphonation, yields f'rimuline i/ellow, a dyestuff discovered by Green in 1887 {J.S.C.I., 1888, vii. 179). It is prepared by heating 2 mols. of p-toluidine with 4-5 atoms of sulphur at 200-280°, and subsequently sulphonating the base thus formed with fuming sulphuric acid. It is evidently a mixture of the sodium salts of the monosulphonic acids of higher dehydrothio-^j-tuluidine derivatives with some of the sodium salt of dehydrothio-/;-toluidine sulphonic acid ; for example, C.igHj-N^OjSjNa C/^>0^,C<^>C.H,.CH, ,S . SO.,Na C,K,< >C.C„H. ■\^N/ ■ NH., I'rimuline is a substantive cotton dye, and gives on this fibre a very pure shade of yellow, which, however, owing to its fugitive character, is not of much technical importance. It can, however, be diazotised upon the fibre and developed with various second components, yielding a number of different colours. This method of producing what are termed the Ingrain colours was first applied to Primuline, and has since been adapted to many of the azo-dyestuflfs. Tlie diazo-salt prepared by diazotising Primuline is extremely sensitive to light, and it is possible to obtain photographic impressions upon cotton cloth by its means. The method adopted is as follows : — Cotton cloth is dyed with 5 per cent. Primuline and then treated with nitrous acid (NaNOj sol. acidified with H.,SOJ, and dried in the dark room. It is then exposed behind a positive for the requisite length of time, when, on developing with an alkaline solution of /j-naphthol, the dark portions of the positive will become red, while the light parts will remain uncoloured, owing to the decomposition of the diazo-salt by the action of the light. Other dyestufFs of this group are : — Tliioflavine T [C] CH3 I r^>-o-if^(OH3)3ci prepared (E.P. 6319^8, 14,884«S; A.P. 412,978) by the methylation of dehydrothio- y)-toluidine with methyl alcohol and hydrochloric or sulphuric acid. It dyes tannined cotton a greenish shade of yellow. Cliloramine ijeUoto [By] is a yellow tannined cotton dyestatf made by the oxidation of dehydrothiotoluidine sulphonic acid. Thioflavine S [C] is prepared by the methylation of Primuline. It dyes tannined cotton canary yellow. Mimosa [G] is formed when the diazo-compound of Primuline is treated with ammonia. It dyes unmordaiited cotton golden yellow. Chromin G [K] is related to Thioflavine S, and is made by melting equal molecules of dehydrothiotoluidine with sulphur, methylating, and finally sulphonating with fuming sulphuric acid. It dyes unmordanted cotton from an alkaline bath lemon vellow. CIIAPTEH XXI. QUINOLINE DYESTUFFS. TuE base quinoline / \/ \ I I I ^\/ N is itself not adapted for the preparation of dyestutl's, but, by tiie entrance of hydrogen atoms into the nitrogen ring it forms tetrahydro-derivatives, wliich will combine with diazo salts to form azo-compounds. It can also be converted into dyestufl's of the triplienylmethane scries. Williams in 1856 (E.P. 109U) prepared the first dyestufF of this series — Gijanine or Quinoline blue [O] — by the action of caustic alkalies on the product of tiie reaction of amyliodide on a mixture of e(]ual molecules of quinoline and ]ei)idine. Its empirical formula is C.iHgjN,!. This dyestuff is not used in dyeing, but tinds application in the colouring of orthochromatic plates for photographic use. Quinoline red [A] is prejiared by the action of benzotricliloride on a mixture of quinaldine /^\/. / \'-. I Js JcH.. and isoquinoline I ,1 yW N in the presence of zinc chloride. It is probably .-i triphenylinethane derivative, and, like Cyanine, is used for the production of orthochromatic photograj)hic plates. For this purpose, mixed with ('yaniue, it is found in commerce under the name of Azaline. The most important dj-estuff of this gro\ip is Quinoline yellow S [A], [B], [By], which is the sodium salt of the sulphonic acid made by the sulphonation of Quinoline yellow (spirit soluble) — quinophthalone — with fuming sulphuric acid. It is an acid dyestufl" largely used in the ilyeing of silk and wool. <.luinoline yellow (spirit soluble) — quinophthalone — is prepared bv the condensation of phthalic anhydride witli quinaldine in the ])rcsence of zinc chloride O O II II C y. yC N N (phthalic anhydride), (quinaldine). (quinophthalone). CHAPTER XXII. INDIGO. Indigo occurs in a number of plants, especially species of Indiijofera, in the form of a glucoside — indican — which, on hydrolj'sis with acids, is decomposed into Indigo blue (indigotine) and a sugar, indiglucine. This dyestuft" has been known from the earliest times, and even at the present day is the most important of all the colouring matters. For this reason it has been the subject of investigation by a number of chemists, the first researches being published between 1840 and 1848 by Erdmann, Dumas, Laurent, Liebig, and Fritzsche. Between 1848 and 1883 a number of constitutional formulae were proposed for indigo, of which the following are the more important : — Baeyer, 1868 CbH.C .HN 1 C6H,C.,HN J (Indigo). CsHjCjHNOH CsH^CJHNH (Indigo white). Strecker, 1868 / CO . / CO , NH< >C : C< \ \C^/ ^CeH/ Emmerling and Engler, 1870 N.C,iH,COCH I II N.CsH.COCH E. V. Sommaruga, 1878 CH : NC^HjC - O I II 1 CH: NCfiH^C-O (Indigo). CH : N - Cr,H,C - OH I II CH : N . CsHjC - OH (Indigo white). E. Baumann and F. Tiemann, 1879 CgH. /NH \ -C :CH No. CeHj; \nh 156 SYNTHFTIC DYF:sTUFFS. N. Ljubawin, 1879 O ,0 : C - NH. c„h/ >c,h ^ ^NH - C : C/ Y l^aeyer, 1882 and Eaeyer, 1883 (1) (1) C O O - c IT N (2) (2) (1) (1) ^C - O - O - c C,-H 1 ' . ' / C,jH NH-C-C NH/ (2) (2) CO . CO . C„H/ >C : Cv ^CiH, ^-NH ^ ^ NH This 1,1st fdniiula, which is now tlie one universally accepted, was arrived at by Bacyer in the following way : — Earlier researches had proved tliat Indigo gave isatin on oxi(hition, aniline when distilled with potash, anthranilic acid / COOH(l)x \ ^NH., (2)/ when fused witii potash, and nitrosalicylic acid and picric acid when treated witii concentrated nitric acid. These researches showed that in indigo at least one benzene ring must be present, and the formation of anthranilic acid indicated tlie presence of the group C i Baeycr in the first instance attempted to reconvert isatin into Indigo by reduction, and in this waj' in 1868, in conjunction with Knop, prepared dioiindol, oxindol, and indol (Ann., 1868, cxlix. 1, 295). The relationsliip between these substances is shown by the followiug empirical foruuila' : — Indigo, C.H NO * Isatin, C.H-NO., Dioxindol, C.H-NO,, Oxindol, C,H-NO Indol, CsH.N " This was, of coui-se, previous to tlic (ii'tenniiiatioii "f the vapour density of Indigo by E. v. Sommaruga in 1879, by which the em|iincal fornnila was shown to be double this, i.e., C|,,H|„N..,0„ {Ann., 187», cxcv. 312). INDIGO. I 5 7 In 1869 Baeyei- and Kmmerling (Ber., 1869, ii. 679) svntbesised indol by melting crude uitrocinnamic acid with potash and iron filings, and in 1870 {Ber., 1870, iii. 517) gave it the formula (1) CH : CH (2) In the same year these chemists also succeeded {Ber., 1870, iii. 514) in converting isatin into Indigo by treating it with phosphorus trichloride, phosphorus, and acetjd chloride, and allowing the intermediate product which is first formed to stand in contact with air. In the same year Emmerling and Engler {Ber., 1870, iii. 885) succeeded in preparing traces of Indigo by distilling nitroacetophenone with zinc dust and soda lime; and five years later M. Nencki {Ber., 1875, viii. 727) also prepared it by the oxidation of indol with ozone ; the yield, however, was extremely small. Seeing that a close relationship existed between indol and Indigo, Baeyer then decided to attempt the synthesis of Indigo by starting with the compound — o-nitrocinnamic acid — from wdiich, with Emmerling, he had succeeded in synthesising indol. The following equations show the difference in empirical constitution between Indigo, isatin, and o-nitrocinnamic acid : — C„H,NOj less CO., and H.,0 ^ CsH^NO * (o-nitrocinnamic acid). (Indigo). CgH^NOj less C0„ and H., ^ CSH5NO., (isatin). The first step in the synthesis of isatin would be, then, to remove two atoms of hydrogen from o-nitrocinnamic acid. This Baeyer effected in the following way : — o-nitroeinnamic acid combines with bromine to form a-y8-dibrom-;S-o-nitrophenyl propionic acid CH : CH.COOH CHBr - CHBrCOOH NO.. CsH/ -^ Br„ -^ C,;H,< \ivrn Two molecules of hydrobromic acid can be removed from this substance by treatment with alcoholic potash, converting it into o-nitrophenyl jiropiolic acid C6H,<(. CHBr - CHBr. COOH .Ci^C - COOH - 2HBr -5. C,S./ ^NOo This important body, which differs from isatin in containing only one carbon and two oxygen atoms, and from Indigo in having one carbon and three oxygen atoms more, was converted by Baeyer into isatin by boiling with caustic alkali, and into Indigo by heating with caustic alkali in the presence of a reducing agent (grape sugar) CjHsNOj less CO., -> CsH.NO, (isatin). C9H5NOJ less CO.j and O -^ CsH,NO * (o-nitropheuyl propiolic acid). (Indigo). * See footnote, previous page. 158 SYNTH KTIC DYEM'UFFS. This synthesis was effected by i^aeyer in 1880, and he also succeeded in prop;iring Indigo from o-nitrophonyl propiolic acid in the following way (Be>:, 1882, sv. 50):— o-nitrophenyl propiolic acid is converted into o-nitrophenylacetylene on boiling with water OeH,<' C^C.COOH /Ce=CH - CO., -> C,;H/ ^NO., If tlie copper compound of this substance is oxidised with an alkaline solution of potassiun> ferriuyanide, di-o-nitrophenyldiacetylene is produced (1) (1) C=C-CsC 0,05/ >CeH, o..n/ (■■i) ■ (2) which on treatment witli concentrated sulpliuric acid yields the isomeric diisatogen, and from this Indigo is formed on reduction with anunonium sulphide. This synthesis is of importance as showinii the existence in Indigo of tlie carbon chain C,;H5 . C . C . C . C - C,;H, The syntlictic preparation of Indigo from c-nitrocinnamic acid is protected by patents D. P. 11,857 and D.P. 15,016, and a method of printing o nitrophenyl propiolic acid (propiolic acid [B]), together with sodium xanthogenate and borax (D.P. 15,516), was also at one time largely employed. But the yield of Indigo by this method is not satisfactory. In the tirst place, b)' the nitration uf cinnaniio acid only a small proportion of the ortlio- nitro-derivative is formed, and although this is increased to 70 per cent, by nitrating the ester, a further loss on converting tiie o-nitroi)henyl propiolic acid into Indigo causes the process to be too costly for practical purposes. It has now been almost completely replaced by other methods, which will be described later. The Hnal facts which led to the elucidation of the constitution of Indigo were supplied by an investigation on isatin and indoxyl. Isatin readily gives metallic compounds which absorb water and pass into salts of isatinic acid. Tlio constitution of this acid and of isatin was given by Kekule as early as 1869 {Ber., 1869, ii. 748) as C«H,<' CO.COOH CO CO C„H/ ^-' NHL, \nH (isatinic acid), (isatin), showing isatinic acid as oamidoplienyl glyoxylic acid and isatin as its internal anhydride. This view was later coiitirmed by Baeyer and Suida {Ber., 1878, xi. 582, 1228; 1879, xii. I.i26), and by Claisen and Shadwell {Ber., 1879, xii. 350), who, at the same time, established the constitutions of dioxindol and oxindol, dioxindol as the internal anhydride of (i-amidomandelic acid, and oxindol as tlie internal anhydride of oamidophenyl acetic acid INDIOO. 159 ,CH(OH)COOH ,CH(OH)CO (o-amidomandelic acid). (dioxiiidol). ,ch:,cooh /Ch, - CO (oamidophenyl acetic acid). (oxiudol). It soon became apparent that isatin could react in two forms — a labile and a stable — the former being incapable of existence in the free state Labile form.' Stable form. /CO CO ,CO C(OH) CeH/ ^ C«h/ -^ (psendoisatin or lactam isatin).^ (isatin or lactim isatiu).- The conversion of isatin into Indigo by Baeyerand Emmerling has already been referred to (see p. 157), and later (1878) Baeyer {Ber., si. 1296) found that this transformation could be considerably improved by treating isatin chloride .00-001 prepared by the action of phosphorus pentachloride upon isatin, with reducing agents. Indoxyl was synthetically prepared by Baeyer in 1881 {Ber., xiv. 1741) in the following way : — Ethyl-o-nitrophenylpropiolate is converted by shaking with concentrated sulphuric acid into the isomeric, ethyl isatogenate (molecular rearrangement) /C^C.COOCoH^ ,00 - C.COOOoHj ^NO, \lJ- O (ethyl o-nitrophenylpropiolate). (ethyl isatogenate). This substance on reduction yields ethyl indoxylate /CO - 0.0000,H5 /0(0H) = C-C000;H5 c,h/ ^/-i - ^ cm/ ---^ \N O \nH (ethyl indoxylate), which is also formed by the action of ammonium sulphide on ethyl-o-nitrophenyl- propiolate /C^C.COOOSs /0(0H):C.C00C„H5 CsHZ " -I- liHl, -> cm/ ^ - " " + H„0 1 Substitution products of the labile form, such as etlij-lpseudoisatin /CO - CO r(C.>H5) are capable of existence. ^ These names were recently proposed by Baeyer {Ber. , xxxiii. (Sonderheft), p. Ixv). l6o SYNTHETIC DYESTUFFS. Ethyl indoxylate on hydrolysis with caustic soda is converted into indoxylic acid, which, on boiling with water, is converted into CO., and indoxyl /C(OH) = C.COOCHi /C;OHj = C.COOH ^COH) = CH OgHX ^^ -> C^S./ -> C,H,< ^NH ^NH ^NH (ethyl indoxylnte). (indoxylic acid). (indo.xyl). It is also interesting to note that isatogenic acid, prepared from the ethyl salt on hydrolysis, is slowly converted into isatin when a solution of it in sulphuric acid is diluted with water and allowed to stand /CO-C.COOH /CO-CfOHi C,h/ „^\ -^ C^h/ ^ - CO, (isatogenic acid). (isatin (hictim)). Indoxyl, like isatin, reacts in two forms : — Labile form. Stable form. CO CH, /C(OH) = CH (pseudoindoxyl or ketoindoxyl), (indoxyl or enoleindoxyl), the former being only capable of existence in the form of its derivatives, as, for example, benzylidenepseudoindoxj'l C0-C = CHC6Hj Indoxyl is quantitatively converted into Indigo on oxidation, a fact which was first noticed by Buumann and Tiemann in 1880 (Ber., xiii. 415). Finally Indirul)ine, a substance which hud been isolated from crude natural Indigo by Schunck (Ber., 1S79, xii. I(i98), was synthesised by Baeyer (Ber., 1881, xiv. 1745) by combining iudo.\yl with isatin in alcoholic solution in the presence of sodium carbonate. The considerations, therefore, which led Bacver to publish bis fornuila for Indigo {Ber., 1883, xvi. 2204) CO , CO . c,H,< >c : c< \c,a, may be summarised as follows : — (1) Indigo contains two imido-groups. (2) The carbon atoms are arranged in it in the same manner as in diphenyl- diacetylene, viz. C^S., -C-CC-C- CeHj (3) It is formed only from those compounds which contain a ketone group directly attached to a benzene ring. (4) Formation and properties show it to be closely allied to indirubine, which is prepared from pseudoindoxyl and pseudoisatin according to the equation /CO. : : /CO. /CO. /CO. CeH/ >CH2 + 0C< >NH -> C.S./ >C : C< )NH (pseudoindoxyl). (pseudoisatin). (Indirubine) (^-indogenide of pseudoisatin). INDIOO. 1 6 I Indigo must therefore be the a-indogenide of pseudoisatin, although its direct formation from pseudoindosyl and pseudoisatin is not possible, owing to the unreactive character of the a-oxygen atom of pseudoisatin, marked (*) in the equation .CO, (* CO. /CO, CO GM/ >C:H„ + 0C< >C„H, -> C«h/ >C : C<' >CeH, (pseudoindosyl). (pseudoisatin). (Indigo) (o-indogenide of pseudoisatin). Baeyer therefore considered Indigo to be a compound formed by the doubling of the divalent group which he termed Indogene, the name indogenide being applied to those bodies containing this group. Indigo white is formed from Indigo on reduction ; it possesses phenolic properties, and its relationship to Indigo is shown by the following formulse : — CO, CO, C(OH)^ C(OHk CfiH/ >C : Cv >CfiH, -> C.n/ >C - C >C8Hj ^ NH -NH/ • NH - \ NH / (Indigo). (Indigo white). Evidently the first action of nascent hydrogen is to form CO . / CO , CeH/ >CH - CHc- >CeH, which then passes into its stable (phenolic) form. The above formula represents Indigo white as dipseudoindoxyl, which accounts for the ease with which it is oxidised to Indigo, since, as already mentioned, Indoxyl is quantitatively converted into Indigo on oxidation (private communkaiion, W. H. Parkin, jun.). Other Syntheses of Indigo. (1) From o-nitrobeiiMldeii yde. Baeyer and Drewson (1882). {Ber., 1882, xv. 2856; 1883, svi. 2205; D.P. 19,768; E.P. 1266*2 . A.P. 257,814 and 257,815.) The condensation of o-nitrobenzaklehyde and acetone yields y-nitrophenyl- lactomethylketone (1) ,CHO p„ rnr-a , CH(OH) CH.,COCH, cm/ -, CH,.CO.CH3 ^ (,,,H,< \no., ^N0„ (•2) (o-nitrobenzaldehyde), (acetone), (o-nitrophenyllactomethylketone), I I l62 SYNTHETIC DYESTOFFS. which ruadily loses water and passes into o-nitroacetociiinamone /CH(OH).CH„COCHa .CH : CHCOCH3 C„H,< ■ -> CeH/ ^NO, \nO,, (o-nitroacL'tociiinanione), from whicli Tndigo can lie prepared on treatment with canstic alkalies. This luothod is used technically in the preparation of Indigo salt [K], which is the sodinni bisnlphite compound of o-nitroplienyllactoniethylketoue, and is employed for printing upon tlie fibre, tiie blue being subsequently developed by immersing the material iu strong caustic soda solution. The production of Indigo from o-nitrobenzaldehyde has become of considerable importance owing to the discovery by Meister Lucius i liriining, of Hiichst, that o-nitrotoluene can he converted into o-nitrobcnzaldehyde. This can bo brought about by three methods : — (a) The action of chlorine on (/-nitrotolucne produces o-uitrobenzylchloride CH..C1 NO,. which condenses with aniline to form (/-nitrobenzvlaniline CH.NH.C,;H, C,,H,>, NO,, On oxidation this is cunvertcd into the corresponding benzylidene derivative ,CH : NC,;H-, ^NO., whicli, on hydrolysis, splits up into o-nitrobcnzaldehyde and aniline O H, CH: NC,H, NO., (b) o-nitrotoluene gives with amyl nitrite, in the presence of sodium ethylate, o-nitrobenzaldoxime ^CH : NOH CoHX ^NO,, which, on liydrolysis with acids, .splits up into o-nitrobenzaldchvde hydroxylamine C„H, O H. CH : NOH NO., ('•) o-nitrotolnene is converted directly into (i-nitrobenzaldehyde by oxidation with manganese dioxide and sulphuric acid CH. CHO C„Hj< ' + 0„ -;■ C,iH.< I -JH.O NO, \nO., A considerable (piaiitity of artificial Indigo is at the present time manufactured by the Bae\ cr and Drewson synthesis. It woiild be impossible, however, owing to the insullicieut epiantity of toluene, to replace the whole of the natural Inditio bv this means. INDIGO. 1 63 (2) K. Heumann's Sijntheds of Indigo. (D.P. 54,626; Ber., 1890, xxiii. 3043; Brunck, Ber., 1900, Sonderheft; E.P. 8726'-"'; A.P. 622,189.) Originally this synthesis consisted in fnsing phenylglycine with potash, whereby it became transformed into pseudoindoxyl HOOC CO c,h,h : ch., -> c„h/ >ch., \ / " \nh/ (phenylglycine), (pseudoindoxyl or ketoindoxyl), from which Indigo can be produced on oxidation. This method, however, remained of purely tiieoretical interest until the Badische Aniline and Soda Fabrik of Ludwigshafen-am-Rhein published their completed method for the preparation of Indigo from the corresponding phenyl- glycine-o-carboxylic acid (see Brunck, Ber., 1900, Sonderheft) (1) COOH NH.CaCOOH (2) The starting-point in this preparation is naphthalene, which, on treatment with strong sulphuric acid and mercury, is converted into phthalic anhydride. From phthalic anhydride, plithnliraide is produced by the action of ammonia, and from this anthranilic acid is formed by the action of chlorine and caustic soda /\/\ /\cOv /\C0\ ^^COOH \y-^ \yCO/ \yCO/ \/NH, (naphthalene), (phthalic anhydride). (phthalimide). (anthranilic acid). Phenylglyciue-o-carboxylic acid is then prepared from anthranilic acid and chloracetic acid ^COOH COOH CeH/ -> CbH/ + HCl NH., + ClCH.jCOOH \nH.CH.,.COOH (phenylglycine-o-carboxylic acid), and is converted into Indigo by heating with caustic soda. An intermediate product in this conversion is the carboxylic acid of indoxyl ■COOH .CO. C,H/ /CHoCOOH -* c,h/ >CH.C00H + H„0 ' \nh/ ■ \nh/ (pheny]glycine-o-carboxylic acid), (indo.xylcarboxylic acid), whicli can be converted into indigo by treating its alkaline solution with air, and has been used for a considerable time under the name of Indoplwr [B] for the production of Indigo on the fibre. This is at present the most important technical method for the production of synthetic Indigo, and it is possible by its means, since there is a sufficiency of 164 SYNTHETIC DYESTUFFS. naphthalene, to replace the whole of the natural Indigo j^early consumed liy the artiticial product. However, since the first jiroduction of tliis Indigo hj- the Badische Aniline and Soda Fatirik in 1897, naphthalene has doubled in price, and it remains to be seen whetiier other sj'ntheses — notably that of Sandmeyer from aniline (see below) — may not in time supersede it. The Indigo prepared by the liadisclie Company is known as IruUgo jjure, and usually occurs as a paste containing 20 per cent, of Indigo suspended in water ; a still more finely divided variety is known as Indigo S. (3) Sandmei/er'g Indigo Si/nfhesit:. This method, the experimental details of which are given in the jiractical portion of the book, consists in converting diphenylthiourea (thiocarbauilide) (from aniline and carbon disulphide) into hydrocyancarbodiphenylimide I c : nc,;h., by the aid of potassium cyanide and lead carbonate. The amide of this "^ C ; NC,H- I CONH, gives the corresponding thioamide on treatment with ammonium sulphide -NH ^^ C : NC,H- I CSNH., which, on treatment with concentrated sulphuric acid, yields a-isatinanilide ,•''^1— NH - C : NC,H, 'J ^° from which Indigo and aniline are produced by the action of ammonium sulphide //^,NH-C : NC„H, \ I ,NH C : C HN, \ 2( I ) + H, -> 1 I I + C,^,NH.. y I CO / I ' coco 1 J (Indigo). Indigo or IndiC,„Hfi and therefore similar in structure to Indigo blue. They are, however, of no technical importance. p, ' CO , ^^ ,S0.;H (Vorliinder and Schubart, NH'\ / Bcr , 1901, xxxiv. 1860.) CIIAlTEi; XXIII. THE SULPHUR OR SULPHIDE COLOURS. These dycstuffs are prepared by fusing certain amido-aromatic compounds with sulphur and sodium sulphide at temperatures ranging from 108-250°. lly this means insolnble coloured substances are produced which cannot be jiuritied by any known means of recrystallisation, but which are soluble in an aqueous solution of sodium sulphide. This solution, which probably contains the dyestuff in the form of a leuco- compouud, possesses marked atiinity for the cotton fibre, and since the dye is readily re-formed by oxidation in the air, tlie sulphur colours are at the present time among the most important of the cotton dyes. They are, for the most part, black and brown, but practically all colours are represented, excepting red ; the sliades are exceptionally fast, but are, however, dull in colour. A dyestuff formed in this way has been known since 1873, when Croissant and Bretonuii-re prepared Cachou de Laval by fusing sawdust, bran, etc., with sodium sul|)hide. This substance dyes cotton direct a greenish shade of yellow, which becomes brown on oxidation in the air, and is rendered exception- ally fast by after-treatment with metallic salts. It is used for producing a cheap fast " bottoming " upon cotton. Investigations by Richardson and Akroyd (Journ. Sor. Cliem. Ind., 1896, 328) show that the pure substance has the empirical formula C^jHigSoi-.O, and that it is probably a derivative of thiophene. It was not until twenty years after the discovery of Cachou de Laval that Vidal applied its method of production to certain paradioxy-derivatives of benzene in the presence of ammonia or amines of the fatty series. In this way he obtained compounds which differed from Cachou de Laval in changing black instead of brown on oxidation on the fibre. Subsequently, Vidal made use of diamines and amidophenols in this reaction, and obtained Vidal black by fusing ^-amidophenol with sulphur and sodium sulphide. The constitution of this dyestutT Viilal supposes to be HOl I- S -I l_NH-l^- S -'\y'OH since he found that by fusing the constituents at a lower temperature he obtained Beruthsen's dioxythiodiphenylamine ho' J- S -I /k)H Vidal also examined the behaviour of meta-derivatives when fused with sulphur and sodiiun sulphide, and obtained brown and black sulphide colours (see also Vidal, Moniteiir scientijique, 11)03, 427). THE SULPHUR OR SULPHIDE COLOURS. 1 67 The great importance of these colouring matters as direct cotton dyes has caused a vast amount of experimental work to be done on their mode of pro- duction, and it is safe to assume that almost every aromatic substance that can be obtained in any quantity has been subjected to the sulphur melt with more or less successful results. Their method of preparation is entirely empirical, and except in a few cases no generalisation has been discovered which regulates their production. It is obvious that by fusing any aromatic compound with sulphur and sodium sulphide a highly complex reaction must be set up, and that the nature of the pro- duct will depend to a considerable extent upon the duration of the melting process. The fact that the products are insoluble in most solvents, and therefore cannot be purified by recrystallisation, renders their scientific investigation a matter of extreme difficulty; but it is almost certain that they are highly complex mixtures and not homogeneous substances. The use of the diphenylamiue derivatives in the preparation of the sulphur colours marks an important advance, which, although not in any way elucidating their constitution, has considerably increased our knowledge of diphenylamiue and its derivatives, since practically every possible compound of this class has been prepared and investigated. The fact that dipheuylamine yielded sulphur colours when fused with sulphur and sodium sulphide was originally observed by Vidal, and it has been since found that the tempei-ature required is considerably lower (140-180") than that previously employed.^ The method is due to Cassella, of Frankfurt, who has introduced a large number of these dyestuffs under the name of the Immedial colours. An example of these colours may be given in Immedial black V [C], which is prepared by fusing ^-oxy-o-^-diuitrodiphenylamine NO./ N-nh/ \oh I NO., with sulphur and sodium sulphide. The above derivative of diphenylamiue and, in fact, other similar derivatives are prepared by combining an amido-derivative of benzene with a chlorobenzene containing a negative group in the ortho-position to the chlorine atom, the combination being usually effected in aqueous or alcoholic solution in the presence of sodium acetate. N0.< \C1 -t- H.H.N<,^^ >0H -s. NO./ \-NH-<( \0H + HCl "I ~' ~l '~ NO. NO., Immedial black produces a fast black upon cotton, which can be oxidised ou the fibre to Immedial blue. Other members of this series are : — Immedial sky blue [C], from dimethyl-^>amido-;)-oxydiphenylamine.- Fast black [B], from 1 : 8-dinitronaphthalene. Kyrogene G and 11 [B] and Kyrogene brown, from 1 : 8-dinitronaphthalene. Sulphur black T, Thionol black [G], Kaligene black [By], Pyrrol black [L], Sulphanil black [K], Pyrogene blacks and blues [I], Melanogen blue [M], Thiogeue blue [M], etc., from dinitrophenol or various amidooxy-derivatives of diphenylamiue (see also Pollak, " Die substantive Schwefelfarbstoffe," Zeit. Farb. C/tem., 1904, 23.3, 253).. ' Even boiling in a reflux condenser has in some cases been found sufficient. 2 See also Ber., 1904, xxxvii. 2617, 3032. CHAPTER XXIV. XANTHONE DYESTUFFS. Indian Yellow or Puiri is the only dyestuff of this group which is of any practical importance. It is prepared at Monghyr in India by evaporating the urine of cows fed on mango leaves. The principal constituent of Indian yellow is the magnesium salt of euxanthic acid, a glucoside, which, on hj'drolj^sis, splits up into glycuronic acid and euxauthone, a dihydroxyxanthone of the formula (Euxanthone (Graebe)). The hydroxyl groups in Euxanthone show, however, a remarkable difference in behaviour ; one of them is readily etherified, yielding an alkyl derivative which is yellow and insoluble in alkalies. The other hydroxyl group cannot be alkjdated by direct methods, and, when this is effected by indirect means, is found to yield an alkyl derivative which is colourless and soluble in alkalies. Since it had been shown by v. Kostanecki and Dreher that hydroxy-frroups in oxyxanthones which are in the ortho-position to the carboxyl group are more difficult to alkylate than any others, the following formula for Euxanthone has been proposed CO OH The synthesis of Euxanthone can be brought about in the following way : — OH CO OH (hydrequinone (^-resorcylic (Euxanthone). carboxyl ic acid). acid). According to v. Kostanecki and Xessler, Euxanthone can also be prepared by condensing hydroquinone carboxylic acid with resorcinol. By sul)stituting phloroglucinol for resorcinol, Gentiseine is produced XANTHONE DYESTUFFS. I 69 the monomethyl ether of which is Gentisine, tlie colouring matter of Gentian root. Xanthone itself is prepared by boiling salicylic acid with acetic anhydride COOH HO^^ II + I I -^ I J, ,1 J + C0, + 2H.,0 Flavone and Flavonole Dyestuffs. In 1895 St. von Kostanecki published his investigations on the nature and synthesis of certain natural colouring matters, which, under the names Quercetine, Fisetine, Luteoline, Rhamnetine, etc., had been used from the earliest times as yellow mordant dyestuffs. v. Kostanecki succeeded in establishing these dyestuffs as derivatives of Flavone and Flavonole O CO (Flavone), (Flavonole), and in many cases prepared them synthetically. The following are the most important dyestuffs of this group : — Flat-one Derivatives. Chi-ysine Apigenine Luteoline O OH ! J, Ji^„ \_/ OH CO 170 SYNTHETIC DYESTDFFS. Flavotwle Derivatice^. Fisetine Qiiercetine OH J Jh/\^C <" ^OH o OH o _l OH^/^C <^ \0H '\/'\^ C(OH) ^— OH CO IViatnnetine CH C OH OH . OH 1 .,• 0H-^,^'C < > OH CO \/ X C OCH , -^ OH CO .l/or(/(e OH 0H,/\|/\ .C-<(_)>OH OH CO And also : — Isorhamnetine _> quercetine nionometliyl etlier. Rliamnazine — > diniethylquercetiue. Myricetine Camphoride — > uxvi|uercetiue. dioxymetlioxyflavonole. CHiri/sine was discovered by Piccard iu poplar buds, and was found by iiiiu to have the empirical formula C,.H,^,Oj. He also found that when boiled with potash it was deconij)osed into phlorogluciuol, benzoic acid, acetic acid, and acetophenone. V. Kostanecki proposed two formulae for tliis substance OH^, OH CO II. but selected formula 11. as being more in accordance with the reactions of the body. Thus it readily explains the above-mentioned decomposition of Chrysine into phloroglucinol, benzoic acid, acetic acid, and acetophenone XANTHONE DYE8TUFFS. 171 \y\y CH -^ C0H5COOH /OH/CO\ OH CH3COOH (benzoic acid) and (phloroglucinol), (acetic acid), OH CO H, CO-CsHj I (acetopheuone). Flavone I I 'CH CO the parent substance of Chrysine, was then synthetically prepared bj- v. Kostanecki in the following way : — o-liydroxyacetophenone was first condensed with benzaldehyde to form a benzal compound \ /COCH H, OHC.aH, OH CO.CH : CHCbHs + H„0 This was then acetylated and brominated, producing ,/\0.C0CH3 \yCO. CHBr. CHBr . C^S.^ which was converted into flavone on treatment with alcoholic potash CO.CH, I -.0 CHBr C^Hs /■\/ I I CHBr \/\C0''' C H Br - C,S., /^/\C-CH I X /"cH CO (Flavone). + 2HBr 172 SYNTHETIC DYESTUFFS. For the parent substance CH V. Kostauecki proposed the name Cliromone, and he prepared methj'lchromone by condensing methyl salicylic methyl ester with acetone by the aid of metallic sodium, and treating the diketone thus produced with hydriodic acid I \°^^'^ + H. CaCOCH., -^ I f^^ CHOH 's^'COiOCH, - ■ '\^ cocacocH CH: /\/° CO.CH \/\co cm. H O /CH CO CO (Methylchromone). C (OH; CH, + C,a,OH Subsequently v. Kostanecki, Tambor, and Emilewicz synthesised Chrysine in the following way : — CH3O. y. /OCH;, i j + c.jhoocc.h, och'^o^^^^ (phloracetopheuone (ethyl benzoate). trimethyl ether). CH.,0. OCH, -*■ C0CH,C0C„H5 OCH, CH. H : I . CO.C.Hr OH O C(OH)iCoH5 U\ /^H, II /CH OH^ O V Y c.c,jH, '\/'\^/CH OH CO (Chrysine). Apit/enine is obtained by hydrolysing the glucoside apiine occurring in parsley ; the formula given above was originally assigned to it by A. G. Perkin, the accuracy of whose view was confirmed by the following synthesis due to V. Kostanecki, Tambor, and Czajkowski : — XA>fTHONE DYESTTJFFS. 173 CH3O. . OCH; '\x - CB-OOC OCH, COCH H OCH (phloracetophenoue (ethyl aniaate) trimethyl ether.) CHsO^ /sxOCH., I I _ OCT^ ^^~ CH2C0 <; 0CH3 CH. i CHO O CO— OCH CH, nz-'Tj- CO >0H Luteoline occurs in Reseda luteola, and has been the subject of a number of investigations by J. Herzig, A. G. Perkin, and others. A. G. Perkin proposed the formula given on page 169, and this was coiitirmed by the following synthesis due to v. Kostanecki, Tambor, and Rozvcki : — OCH; OCH, OCH, CHO 0C\ ^OCH, OCH COCH,H (phloracetophenone trimethyl ether), (ethyl salt of veratric acid). OCH3. .. /OCHs Y r ^^^ O^^CO.CH,.CO<( ^OCH, nx OCH, H OH och3. ^^ ,0 co- y~ och3 1 1 „c!h, o^^co 1 /-' - ,0 CrOH)-< >0H -> OH,/ f - \-/ CH OH CO OH ^ OH/^\,^,C-Y 'OH ^-CH — • OH CO (Luteoline). The other dyestuffs of this group have not yet been syntheticallv prepared, but their constitutions have been placed beyond question by the researches of V. Kostanecki, Herzig, A. G. Perkin, and others. CIIAPTKi; XXV. A SHORT REVIEW OF THE SYNTHETIC DYESTUFFS. (Compare Dr H. Caro, Ueha- die Entwickhiufj iler Theerfarheniiuhistrie, Berlin, 1893.) TiiK first artiliciiil dj-c.-ituti's were Picric acid, prepared in 1771 by Wuulfe from Indigo and nitric acid ; and Rosolic acid (Auriuej, discovered V>y Runge in 1834. Neither of these compovmds were, however, mannfactured on the com- mercial scale owing to the then considerable cost, of tlie materials from wiiicli they were derived; and it was not until \^bb that a technical method was introduced for the production of Picric acid from coal-tar. The era of the synthetic dyestuffs dates, however, from the discovery of Mauveine in 1856 by \V. H. Perkin, and its commercial manufacture in 1857 by Perkin & Sons at Greenford Green, near London. Perkin's discovery, that a colouring matter could be produced by the oxida- tion of aniline, led to the study of the beiiaviour of this base towards various oxidising agents, with tiie result that in 1859 Yerguin prepared Fuchsiu (Magenta) by the oxidation of crude aniline by me.ins of tin chloride, and manufactured it in conjunction with the lirm of Kenard Freres, of Lyons. Magenta had, however, been previously jirepaied by Natanson in 1856 from aniline and ctiiylcnechloride, and in 1858 by A. W. llofmann from aniline and Carbon tetrachloride. In 1860 tlie method of preparing Magenta by oxidising aniline with arsenic acid was introduced by Nicholson, Girard, and de Laire; and in the same year Girard and de Laiie prepared the first blue synthetic dyestuff— Rosaniline blue — by treating Magenta with aniline. The recognition l)y llofmann of the nature of this reaction, i.e. the phenyla- tion of Rosaniline — led iiim to try the etlect of introducing alkyl groups instead of phenyl groups into the Rosaniline molecule, and by tliis means he prepared llofmann's violet in 1863. In 1862 Nicholson made the important discovery that Rosaniline blue could be converted into a sulphonic acid by treating it witli sulphuric acid, and tliat tlie sodium salt of this sulphonic acid was soluble in water ; soluble Rosaniline blue (Water blue, Nicholson's blue) was in this year manufactured by the lirm of Simpson, Maide, ct Nicholson, and in the same year Aniline black was first prepared by Lightfoot. As early as 1861 Lauth had prepared Metiiyl violet by treating dimethyl- aniline with oxidising agents ; but it was not until 1866 that, in conjunction with Ch. Baidy, he introduced a metiiod for the technical jiroduction of dimetliylaniline, and conseipieutly of Methyl violet, which in 1867 was technically prepared by Poirrier and {'lia]ipat. Tills dyestuil' quickly re[ilaccd llofniann'.s violet. The tirst grein synthetic dyestufl' was Aldehyde green, discovered in 1862 by Cherpin ; but it was quickly replaced by Iodine green (Koisser, 1866), which, in A SHORT REVIEW OF THE SYNTHETIC DYESTUFFS. 1 75 its turn, gave way to Methyl green, prejii^red by the action of methyl chloride on Methyl violet (Wischin, 1873). During this period Nicholson (1861) isolated Chrysaniline from the Magenta melt, and its nitrate was manufactured under the name of I'hosphine. The nitrobenzene process for the manufacture of Magenta was discovered by Coupler in 1 866, and led him in the following year to prepare the first soluble Induline. A spirit-soluble Induline had, however, been prepared in 1863 by Dale and Care. The decade 1860-1870 also witnessed the introduction of Bismarck brown (Martins, 1863), Martins yellow (1864), Palatine orange (1869), and Magdala red (Clavel, 1868). Meanwhile the Kekule benzene theory had been established, thus opening up a new era in the manufacture of the synthetic dyestufi's. The former purely empirical reseai'ches then gradually gave way to well-directed scientific syntheses ; and the constitutions and mode of production of the various compounds already prepared were step by step elucidated. The first example of such synthesis is afforded by the synthetic production of Alizarine by Graebe and Liebermaun in 1868; and its commercial production by the method of Graebe, Lieberinann, and Perkin in 1869. "Whilst the chief attention of chemists was occupied with the synthesis of Alizarine, another class of dyestufi's — the azo-compounds — appeared in 1876 in commerce. The azo-compomids themselves had already been discovered by Grie.ss, and their constitution elucidated by Kekule ; moreover, one member of this group — Bismarck brown — had already been prepared, since 1863, on the commercial scale. It was not until this j-ear, however, that Witt discovered Chrysoidine, and that Caro indicated the technical value of the Griess method of preparing azo-compounds. In the same year Roussin prepared the Oranges, and Ldebermann and Ullrich succeeded in transforming Alizarine into its sulphonic acid. When the azo-dyestufts were first iutroduced, it was considered that only orange and yellow dyestufi's could be formed by this means. This idea was, however, dispelled by the discovery of Fast red A by Caro in 1878. This year also saw the introduction of a number of important dyestufi's, amongst others being Alizarine blue. Malachite green, and the Ponceaux. In the preparation of the last-named, the important naphthol and naphthyl- amine sulphonic acids were, for the first time, used commercially, and their great value as second components in the preparation of azo-dyestufis indicated. The year 1878 also witnessed the commercial manufacture of Galleine and Cajruleine, dyestuffs which had previously been prepared by Baeyer in 1871. In all the azo-compounds mentioned above, the sulphonic acid group plays an important part, and the application of Nicholson's method of sulphonation to other members of the triphenylmethane series enabled Caro in 1887 to prepare Acid magenta, Acid violet, etc. The first disazo-dyestufi' — Biebrich scarlet — was prepared by Nietzki in 1879, and in the same year Caro prepared the important nitro-dyestuff, Naphthol yellow^ S. The year 1880 witnessed the completion of the Baeyer synthesis of Indigo, and in 1883 the. introduction of Phosgene gave rise to the Phosgene colours (Caro and Kern). The first of these dyestuffs— Crystal violet — appeared in this year, and was followed by a number of colouring matters of the same class. In 1 88-1: Bijttiger discovered the fact that Congo red was substantive to cotton — a discovery which gave rise to the preparation during the following decade of 176 SYNTHETIC DYESTUFFS. a vast number of azo-compounds from Benzidine and allied bases, which constitute the important group of the substantive cotton azo-dyestuffs. In this year, also, Tartrazine was prepared. In 1868 the property possessed by fuming sulphuric acid of introducing hydroxyl groujjs into Alizarine and its derivatives was discovered by Bohn, and in the following year was applied to the preparation of a number of valuable dyestutfs by K. 8chmidt. *Iu the same year the Oxazines were introduced, as well as the liosindulines, by Fischer and Hepp. In 1889 formaldehyde was api)lied to the synthesis of dyestuffs by the Htichst Farbwerke, leading, not only to the synthesis of new members of the triphenylmethane series, such as New fuchsin, but also to the production of the Pyroniue and Acridine dyestuffs. At this period the method of producing insoluble azo-compounds directly on the fibre was indicated by the discovery of Primuline in 1887 by Green. The more recent advances in the domain of the synthetic dyestutfs include the preparation of synthetic Indigo (Indigo pure) by the Badische Aniline and Soda Fabrik in 189?! This firm, after many yeai-s of research, has succeeded in adapting the Heumanu synthesis to commercial conditions, and now prepares artificial Indigo on a scale which will probably cause it to ultimately completely rejilace the natural product. The production of the sulphur colours marks an advance more from the point of view of the dyer than of the scientist, since the nature of them is still very obscure. The empirical attempts made to produce these compounds vividly recall the earlier experiments in the preparation of the aniline dyestuffs. Our knowledge of the natural colouring mattere has been considerably increased by the work of S. v. Kostanccki on the Flavones ; and by that of J Herzig, W. H. IVrkin, junior, and others, on Braziline, the colour principle of Redwood, and on Hffimatoxyline, the colour principle of Logwood. The yearly production of the artificial dyestutfs represents a value of about £8,000,000, of which fonr-fifths is produced in Germany, and the other one-fifth divided amongst Switzerland, England, and France. PART II.-PRACTICAL. CHAPTER XXVI. THE TECHNICAL LABORATORY.^ There are certain dift'erences between tlie technical or works laboratory and that usually found in Universities and in Technical Schools ; and, although the preparations and technical operations described in the following pages can all be carried out in the ordinary scientific laboratory, yet in cases where a laboratory can be set apart for purely technical work (as is the case in chemical and other works, and in the larger chemical schools) a few details as to the arrange- ment and fittings of such a laboratory may be here given. (The general arrangement and construction of chemical laboratories and their fittings is admiraljly described by Russell, The Planning and Fitti7ig-up of Chemical and Physical Laboratories, Batsford, London, 1903.) In the first place, the space apportioned to each worker must be much greater than that usually allowed, even in an advanced scientific laboratory. Not only is the work carried on on a larger scale, but the technical student or chemist will often be able to have half a dozen different experiments going on at one and the same time. Thus he will perhaps start a sulphonation experiment at the beginning of the day which requires only slight attention for the regulation of the temperature. A condensation requiring a flask and reflux condenser takes up a good deal of room, and generally proceeds for several hours by itself without any attention beyond an occasional test. During the morning, too, there will be several substances, left from the day before, to be filtered at the pump ; and, finally, it may be necessary to stir mechanicall}' as many as half a dozen or more beakers, which alone would occupy an ordinary student's bench. It is often very convenient, also, to set apart a wdiole or a portion of a bench for the purposes of analysis ; upon which will stand several burettes containing standard solutions, and adjacent to w hicli may be a shelf or shelves containing the more generally used chemicals and reagents. Besides this, the laboratory should contain at least one large draught chamber, a large sink with draining-board and draining-pegs, and enough space to accommodate one or more autoclaves aud other large pieces of apparatus. Wide shelves should be fixed round the sides of the laboratory, or in a suitable place, for holding large bottles and tins as well as apparatus. If there is no dye-house or dyeing laboratory in connection with the technical laboratory, an experimental dye-bath should also be provided. The benches may be con- structed of pitch pine or stained American white-wood, and should be fitted with drawers for storing corks, test and filter papers, etc., and a wide shelf underneath. The top of the bench may be of teak, but in technical laboratories ' The term " technical " used in this work refers, of course, only to that branch of applied organic chemistry specially dealt witli. 177 12 1/5 SYNTHETIC DYESTOFFS. it is often made of oniinary wood upon whicli is sheet-lead, hi tills case a hard- wood lillet is screwed to the edge of the l)eiich-to|>, projecting' up about ^inch, and the lead is dressed over the top of it. If the bench is double, i.e. arranged for Work on each side of it, a channel should run down the centre, to carry away waste water from turbines, condensers, etc. If against the wall, the channel will be at tiie back. The laborator\' must, of course, be supplied with the usual gas and water connections ; in many cases it is useful to have electricity also, for electrolytic work and driving small motors for stirring, shaking, etc. ; finally, steam can usually be easily fitted, especially In chemical works. The gas pipes should run along the front of tlie benches, and small branches carrying taps are fitted at convenient distances along it, over which a rubber tube can be slipped. In the case of a lead-covered bench, as described above, each gas branch is bent neatly over the top of the fillet ; but where an ordinary straight teak top is fitted, a semicircle of wood is cut out of the edge of the teak (S inches diameter), in place of which is the gas branch so arranged that no part of this Is above the level of the table. This is by far the best arrangement of the gas jiipes, as, in case of accident, the gas is easily turned off at the front of the bench, and also there Is no danger of accidentally breaking glass flasks, etc., by contact witii a jirotruding gas jet. (This is the arrangement in the chemical laboratories at Heidelberg.) Besides the ordinary gas-fittings, there sliould be one or two specially large brunches, on a free wall side if possible, to which a large Fletcher burner can be fixed for heating autoclaves, large pans, etc. For each worker there must be arranged a suction pump and a niedianlcal stirrer. The former, to be used for filtering and all operations conducted under diminished pressure, is best arransred by soldering a water pipe to a metal pump. These (which cost about three shillings) cannot be satisfactorily united with the water supply by rubber tubing. A piece of ordinary rubber tubing is fitted to the exit tube of the pump, tn carry away the waste water, and a piece of thick-walled tubing — "pump tubing" — attached to the side-tube. This ]iumj) tubing may either be connected directly with the filter-flask or with one or more T-picces carry- THE TECHNICAL LABORATORY. 179 ing glass taps, so as to allow two or more attachments to the suction. In existing laboratories, where no provision has been made for filtering under reduced pressure, it is exceedingly convenient to join a rubber-lined brass " union " to the metal pump by means of a short length of lead pipe, and then to attach this temporarily to the water pipe when required. The " union " should of course fit fairly tightly when slipped over the nozzle of the water pipe. In this way half a dozen metal pumps will enable a large number of workers to filter with suction at their own benches (see fig. 1). For driving the mechanical stirrers or agitators eitlier water or electric power is used. In the case of the former, a small Rabe's turbine is eitlier permanently fixed at a suitable point and connected with the water supply by means of a lead pipe soldered to it, or a rubber-lined brass " union " is soldered to the inlet tube Fig. 2. of the turbine, so that the latter may be fixed to any water pipe in the labora- tory. A wide rubber tube is attached to the exit pipe of the turbine in order to carry off the waste water. If a small electric motor is used to provide the power, this is fixed in a suitable position on the working bench. The stirring arrangement consists of a suitably bent glass rod, the straight part of which passes through corks fixed in the liollow axis of a wooden grooved wheel (see fig. 2). The whole is lield firmly in the clamp of a retort-stand by means of the brass (or glass) tube through which the glass rod passes, friction between the revolving wheel and the top of the tube being avoided by interpos- ing a tin support which is cut in the shape shown, the four arms being bent up at right angles to the centre part (fig. 2, a). The stirrer is driven from the motor or turbine wheel by means of an endless rubber cord. A piece of solid rubber cord about 3 feet long is chosen, and the ends cut at a very acute angle. The tapering parts are laid together and bound firmly with stout thread. I So SYNTH FTir llYRSTUFFS. If the uuioii is nuiitly done, there will he no tendency for the cord to become displaced when in use. Several stirrers are easily driven siniultaneously by connecting them in series hy such endless rublier cords. A very necessary adjunct of the technical laboratory is the library. This should be well stocked with the standard works on the subject, as well as the periodicals treatinj; upon this branch of Applied Chemistry. The following list includes the more im|>ortant works on the subject: — 1. (llCSERAI, LlTKliATUHE (B.XCErTlNG PaTENT LiTEHATURE). Lunge, IHstiHativn of Cual-Tar and Ammonia, 1900. Benedict (translated by Knecht), Chemislnj of the Coal-Tar Colours, 1886. Nietzki (translated by Collin and Richardson), Chemistry of (lie Organic Dyestiiff^, 1892. Haiinsen, Dif Fahrlkation tier Theerfarhstoffen und Hirer Rohmaterialien, 1889. Schultz, Dir Chemie des Steinkohlentheers, 3rd ed., 1900-1901. Georgievics (translatod by Salter), Chemis/ri/ of J)i/eslufs, 1903. Seyewetz ami Sisley, CIrimie des Mali' res t'oloi-antes Aiiificielles, 1896. L. Lefevre, Les Mai it res Colorantes Artifirielles, 1896. Dupont, L'Indiistrie des Mattered Colorantes, 1 902. Meldola, (.'oat and what we get from it, S.P.C.K. Schultz and Julius (translated and added to by Green), Surrei/ of the Uiyanic Cohinriwj Maltn-s, 1904. Thorpe, J)i in th(? preparation of the raw materials for the production of dyestuffs are the following : — 1. Suipliuncdion ; introduction of the group SO^H.' 2. Nitration and reduction; introduction of the groups NO._, and NH^. 3. Diazotisatiun anil subsequent builimj witli loater ; conversion of the NH., group into the OH group. 4. Conversion of i/ie NH.> group into the OH group by boiling with dilute acids or alkalies. 6. Fusion of the SO.,H group with caustic allcali : forming the OH group. 6. Conversion of tlw OH group into the NH., group by treatment with ammonia. 7. Molecular rearrangement of the SO3H group by heat. 8. The elimination of the SO^H group by treatment with acids, etc. Examples of these processes and a description of them will be found in the following pages. Conversion of the NH. group into the OH group by boiling- with dilute acids or alkalies. — This is an operation very frequently carried out un the large scale, and is particularly applicable to the case of the amido- or diamidonaphthalene sulphonic acids. ' III the naiiliUmleiie serifs this group never enters into i\\cortho-,para-, or pen -position with regard to a .sulplionic acid group already in the o-]"isition, i.e. SO.H 8 1 ' 6\/\/'3 on further .sulphonation never gives a 1 : 2, 1 : 4, or 1 : 8 disulphonic acid ; and if the first SO,.^ froup is in a;3lio.sition, the second never entei's into the corresponding ortho-position, i.e. a 1 : 2- isulplionic acid is never obtained. See also Chcm. Zeii., 1893, 75S ; 189-1, 180; I'roc. C.S., 1890, 130 ; licr., 1894, xxvii. 1209 ; and p. 11 of this book. THE TECHNICAL LABORATORY. 1 95 The process in man)' instances is carried out by heating with water alone, of course under pressure. Thus by heating a mixture of the acid iif formula NH, and three parts of water to 180°, the corresponding a-naplitliol disulphonic acid is formed. It is usual, however, to employ dilute hydrochloric or sulphuric acid. When two amido-groups are pi-esent, the reaction may be so modified by the regulation of the temperature that only one NH., group is converted into OH, the second being changed at a higher temperature. Thus the acid of the formula SO.^l J. JSO3H on heating with water, dilute acids, or dilute alkalies, gives first NH., OH SOjHI J. .kOjH (H acid), and at a higher temperature OH OH /\^\ (chromotropic acid). SOsri. I ISO3H When the diamido-acid is asymmetric, the NH^ group nearest to the sulphonic acid group is the first to be converted ; thus : — NH, NH, NH, OH NH, NH, NH, OH I 1 I, BO^ In a few cases alkalies, such as milk of lime or dilute caustic soda, are used. With regard to the use of dilute caustic t I I In the naphthalene series there are many striking examples of this molecular rearrangement. Thus naphthalene itself, on treatment with sulphuric acid at a low temperature, forms naphthalene-a-sulphonic acid ; but if the temperature be raised, the /3-compound results. The general tendency in the naphthalene series is for the sulphonic acid group to migrate in the first instance from an a?p7(a-position to a 6ete-position (when the temperature is raised) ; and, when the other group in the molecule is an SO,H group, any further migration results in a compound having these groups as widely separated from each other as possible, the /i-position being, however, always preferred. Thus naphthalene-a-snlphonic acid, on further sulphonatiou, gives the following :— SO3H SO3H The formation of the latter acid at a higher temperature is regarded as having been preceded by the initial foi-mation of the 1 : 5 acid, which undergoes molecular change in the direction indicated, at a higher temperature. Further, on sulphonatiug naphthalene-/i-sulphonic acid we obtain rr^^ 1SO3H colli in a similar way. An interesting case of molecular change where an excess of sulphuric acid is not present is that undergone by naphthionic acid. If this substance be heated with two to three parts of naphtlialene to the boiling-point of the latter (217°), the SO„H group migi-ates from the a-position to the ^-position ; thus : — NK, I I ! NH., ^ ,SO.H IqS SYNTH CTIC DYESTUFFS. It is wortliy of remark, liowever, that this latter acid is not formed at all by the sulplioiiatidii of u-iiaplilhylamiiie, but, up toa certain temperature, iiaphthionic ;iciil is the sole product. Similar cases to those cited above occur in the case of the /3-napiithol sulphonic acids. If /i-naphthol be sulphouated at a low temperature, we obtain the acid SO^H but at a high temperature this passes into the acid ,0H (See also the description of the other /3-naphthol sulphonic acids, especially the disulphonic acids R and U on p. 16.) CHAPTER XXVII. PREPARATIONS OF INTERMEDIATE PRODUCTS. I. BENZENE SERIES. 1. Nitrobenzene, C„H.NOo. u 50 grams benzene. 60 „ cone, nitric acid, sp. gr. 1'4 (43 c.c). 90 ,, cone, sulphuric acid (50 c.c). The nitric acid is added in small portions at a time to the sulphuric acid contained in a small flask. During this process the flask is well cooled under the tap. The mixture is transferred to a tap-funnel and added slowly to the benzene in a half-litre flask. The flask is well shaken and cooled after each addition, and the temperature must not be allowed to rise above 25° until nearly all the acid has been added, when it may reach 50°. A wide glass tube is now attached by a cork to the flask, forming a vertical air-condenser, and the nitration mixture is heated in a water-bath (water at 60°) for one hour, being frequently shaken. The contents of the flask are poured into about 1 litre of water, when the nitrobenzene sinks to the bottom. If the settling is not at once complete, the mixture is allowed to stand for some time. A large portion of the acid solution may be decanted, and the rest, together with the nitrobenzene, is transferred to a separating funnel and the nitrobenzene drawn oft', the top layer of acid being thrown away. The former is again transferred to the funnel, three or four times its bulk of water added, the whole shaken, and. after settling, the oil again drawn off. This operation is repeated once more, after which the nitro- benzene is run into a distilling flask of about 300-400-c.c. capacity, which is then fitted with a thermometer and connected with a long glass tube about 8—10 mm. in diameter, forming an air-condenser. The oil is distilled over the free fiame. At first water and benzene pass over, then the temperature rises rapidly to over 200°, when the receiver is changed and the nitrobenzene collected at 204-207°. Yield 55-60 grams. The yield obtained on the large scale corresponds to 75 grams. The difterence is accounted for by the fact that, on the large scale, the stirring is continuous and no nitrobenzene is lost in the wash- waters. Any benzene, also, which is recovered by distillation is nitrated with the next batch. Properlies. — Light yellow liquid, with a smell of bitter almonds; B.P. 206-207°, M.P. 3°, sp. gr. at 15" = 1-208. Nitrobenzene comes on the market as (1) light or pure nitrobenzene, B.P. 205-210°, sp. gr. 12; and (2) heavy 200 SYNTHKTIC DYESTUFFS. nitrobenzene (containing nitrotoluenes), B.P. 210-220°, sp. gr. ri8. The terms " light " and " heavy " apply, not to the specific gravities, but to the boiling-points. Commercial nitrobenzene is tested by determining (1) the boiling-point and (2) the spociiic gravity. Use. — Pure nitrobenzene is used for the manufacture of aniline, benzidine, and in perfumery. Heavy nitrobenzene is used in the manufacture of Magenta. Equation. — Hi OH NO, A NO, /\ I I Tlic sulphuric acid acts as a dehydrating agent. 2. Aniline. NH, /\ 1 I ^y 100 grams nitrobenzene. 120 ,, iron powder. 10 ,, cone, hydrochloric acid. The reduction of nitrobenzene, as well as other nitro-bodies, is carried out on the large scale by the use of iron borings. This cannot be satisfactorily imitated in the laboratory ; consequently it is usual to reduce nitrobenzene on the small scale by means of tin and hydrochloric acid. If, however, very finely divided iron or " iron powder " be used, the reduction proceeds very smoothly, and a yield equal to that given l)y the former method is easily obtained. The iron, together with 160 c.c. water, is placed in a large flask of 2-3-litres capacity and well shaken. The flask is now warmed slightly, and a few drops of nitrobenzene added. Then the acid is poured into the flask, and the remainder of the nitrobenzene in small portions at a time. After each addition the flask is thoroughly well shaken and cooled under the tap. The addition of nitrobenzene and amomit of cooling are so arranged that the temperature keeps at about 80-90°. When the reaction is finished (shown by no further rise in tempera- ture on shaking), the contents of the flask are distilled with steam (it is not necessary to make the mi.xture alkaline) till the distillate is no longer milky. The volimie of this will be about 400-500 c.c. The distillate is transferred to a separating funnel, allowed to settle (if nccessar}'), and the aniline, which forms the lower layer, drawn oft'. The water (which, on the large scale, is returned to the steam boiler, as it contains about 3 per cent, of aniline in solution) is now saturated with connnon salt and allowed to stand for some time. The aniline, which rises to the top, is separated by means of a separating funnel, added to the first portion of oil, and the whole distilled. A little water passes over at first and is separately collected ; the aniline then passes over at 182°. Yield 50-70 grams. Properties. — Colourless oil with a peculiar smell; B.P. 182°, sp.gr. 1020 at 15°. PRKPARATIONS OF INTERMEDIATE PRODUCTS. 20I Commercial " pure aniline " is tested by distillation. At least 90 per cent, by volume should distil at 182". It should give a clear solution with hydro- chloric acid ; a yellow colour indicates the presence of nitrobenzene. "Aniline for red" (i.e. for the manufacture of Magenta) is a mixture of aniline (3.5 to 42 per cent.), orthotoluidine (35 to 50 per cent.), and paratoluidine (14 to 24 per cent.). It results from the reduction of " heavy nitrobenzene." It should boil between 190° and 200°, and have a specific gravity of TOOT to 1-009 at 15°. Use. — Aniline is used for making a large number of its substitution products, as well as for Qiiinoline, Induline, Magenta, Aniline blue, diazobenzene salts (for azo-dyes), and Aniline black. Eqitation^. — NO.J NIL, I I + 3Fe + 6HCl -* | | + 3FeClo + 2H..O \y (See also p. 19.) 3. Acetanilide. NH.CC.JIsO) /\ I I \/ Walter, Aus der Praxis der Anilinfarhenfabrilation, 1903. 200 grams aniline. 150 ,, glacial acetic acid. The aniline and acetic acid are mixed in a round flask of one-litre capacity, fitted with an air-condenser, and boiled on a sand-bath for ten to twelve hours. The tube forming the air-condenser should not be too long, in order that the water vapour may escape while the aniline and acetic acid are condensed. The hot liquid is poured into hot water containing 30 grams of concentrated hydrochloric acid, and the whole well stirred. After cooling, the acetanilide is filtered at the pump and washed with water. The filtrate contains about 20-30 grams of aniline as hydrochloride, which, on the large scale, is regained. The acetanilide is transferred to a porcelain dish and dried at 110-120°. On cooling, the solidified product is broken up and powdered in a mill Yield 220-250 grams. Fro2)eiiies. — Acetanilide is difficultly soluble in cold, more easily soluble in hot water, froiii which it crystallises in white leafy crystals ; M.P. 115°, B.P. 295°. By boiling with concentrated hydrochloric acid, it is hydrolysed to aniline and acetic acid. Use. — Acetanilide is used largely for the preparation of />nitraniline. Equation. — NHj NH.^.CH^COOH NH.,.CH,COOH NH(CH,CO) /\ /\ /^' ' /X 1 1 + CH COOH -> 1 • , 1 ! + H.,0 \/ \/ \y "^ \/ (aniline acetate). 202 SYNTHETIC DYESTUFFS. 4. )>-Niiracetanilitle. NHCCHjO) /\ ' I I \/ Walter, Aus der Praxis Jer Anilinfarben/abrikaium. 100 grams acetanilide. 300 „ cone, sulphuric acid (167 c.c). 62'5 „ cone, nitric acid (44 c.c). I 50 ,, cone, sulphuric acid (28 c.c). ) The acetanilide is dissolved in 300 grams of sulphuric acid contained in a round flask, the temperature not being allowed to rise above 40 . The solu- tion is cooled to 5-10" by immersion in ice- water, and the cooled mixture of 625 grams of nitric acid with 50 grams of suliihuric acid is added very slowly. After each addition the flask is well shaken and cooled in the ice-water, the temperature being kept below 15". After standing a short time, the nitration mixture is poured into about 10 litres of water containing several lumps of ice, when the y)-nitracetanilide separates out, and is filtered, washed free from acid, and dried on a porous plate. Yield 110-120 grams. Properties. — ^/(-Nitracetanilide crystallises from alcohol in almost colourless needles; M.P. 207°. The presence of orlhonitracetanilide is detected by extracting with chloro- form, in which the c-compouud is soluble. The technical product should give the calculated amount of /)-nitraniline on boiling with hydrochloric acid, which is tested by titration with standard solution of sodium nitrite. t7.-Nitracetanilide is used for the preparation of ^i-nitraniline and 7>amidoacetanilide. Equation. — NH CB O NHCCSjO) I i + HNO -> I I -t-H.,© NO.. 5.' j>-Nitraniline. NHo 'J NO,, 100 grams yi-nitracetanilide. The acetyl compound is boiled with 250 c.c. of dilute sulphuric acid (25 per cent.) in a round flask attached to a reflux condenser until the whole dissolves. The clear solution is jwured into a beaker, and the free base precipitated by adding dilute caustic soda solution till alkaline. After cooling, the ^>-nitraniline is filtered, reerystallised from hot water (on the large scale this is done under pressure), and dried on a porous plate. Yield 70-75 grams. Properties. — Yellow needles or prisms; .M.P. 147° : dissolves in 1250 parts of water at 18° ; not volatile with steam. The commercial product should be a light PREPARATIONS OF INTERMEDIATE PRODUCTS. 2O3 yellow powder, having the correct melting-point, and dissolving without residue in hydrochloric acid. It is tested by titration with standard sodium nitrite solution. For details of diazotisation, see p. 236. Use. — ^)-nitraniline is used in the production of azo-dyes, and also for the preparation of its diazo-compound, which, by combination with y8-naphthol on the fibre, yields paranitraniline red. Equations. — nh(c.b:.0) /nh„\hjsOj 2| j + H,3SOj + 2H.,0 -* I ! [| + 2CH.jC00H NO, NHlA H.50j I I + 2NaOH -^2 1 I + Na2S04 + 2H„0 NO., 6. p-Amidoacetanilide. 0" NH., Nietzki, Bei:, 1884, xvii. 343 100 grams ;)-nitracetanilide. 100 ,, iron powder. 20 ,, acetic acid, 30 per cent. The iron and acetic acid are placed in a round flask, together with 300 c.c. of water, and about half of the nitracetanilide is added. The flask is well shaken and gradually becomes warmer as the reduction proceeds. The rest of the nitro-compound is gradually added, and the temperature is not allowed to rise above 80°. The end of the reaction is reached when tlie contents of the flask lose their yellow colour and the temperature, after shaking, falls. Sodium carbonate solution is then added till an alkaline reaction is obtained, and the mixture filtered hot at the pump. The residue is boiled up several times with water and filtered again. Tlie united filtrates are saturated with salt, and on cooling fine needle-shaped crystals of amidoacetanilide separate out. They are filtered, and dried on a porous plate. Yield .'iO-CO grams. On the large scale, amidoacetanilide is purified by distillation in vacuo (in which form it is sold), or the reduction liquor is diazotised direct for the production of azo-colours (direct cotton blacks). Properties. — M.P. 161°. Analysis: with half-normal sodium nitrite solution. Equation. — . NH(C.3:30) NH(C.B.O) .^. ' /\ ■ " I I I- SH, -5. I \ + 2h:,o ^ ' \y ' NO2 NHj 204 SYNTHETIC DYESTrPFS. 7. p-Sulpfianilic arid. ^\' I I Neville aiKrWiiither, Her., 1880, xiii. 1940. Miihihiiiiser, Ding. pol. J., 1887, cclxiv. 187. Paul, Zeit. ang. Cliem., 1896, 685. 100 grams aniline. 110 ,, cone, sulphuric acifl (61 c.c.). The aniline is stirred into the aoiil contained in a shallow porcelain basin, and the acid sulphate thus obtained (C,;H.NH^.H^SOj) is heated in an oven till the temperature reaches 205°. This must take four hours. The oven is kept at this temperature for six hours more. The product is broken up and dissolved in hot water with addition of 40 grams of caustic soda. (An alkaline reaction must be obtained.) The solution of sodium sidphanilate is boiled for a few minutes with a little animal charcoal and filtered hot. On acidifying with h_ydrochloric acid (Congo pajier must be turned blue) the sulphanilic acid crystsillises out ; after standing overnight it is filtered at the pump and dried at 100°. Yield 150-160 grams. Pirrperties. — Sulphanilic acid crystallises from water in large colourless plates containing one molecule of water of crystallisation, which, however, is easily driven off. It is sparingly soluble in cold, more easily in hot water. The technical product, which is not purified on the large scale, is usually dark grey. It should dissolve in alkalies, giving a clear solution containing only a trace of black insoluble matter. The strength is determined bj' titration with standard sodium nitrite solution. Use. — Sulphanilic acid is used largely in the preparation of a7.o- f j + BL,0 NiCn-J)., N(CH,)., (uitrosodimethylaniline (base)). 10. Diethyl-m-amiilophenol. N(C,>H5), A.P. 403,678 ; D.P. 44,792S8. Wolfrum, Chemisches Praktikum, Pt. II. 326. 50 grams diethylaniliue. 150 „ fuming sulphuric acid, 30 per cent. SO3. The acid is placed in a 500-c.c. round flask (fitted with a reflux condenser) and heated on a boiling-water bath. The diethylaniliue is added drop by drop during half an hour. The heating is continued till a sample, rendered alkaline and extracted with ether, gives no residue of diethylaniliue after evajjoration 206 SYNTHETIC DYESTDFFS. of the ether. The product is then iillowed to cool, poured into 1 litre of water, and nearly neutralised with milk of lime, the complete neutralisation being effected by the addition of chalk till this produces no more ctlcrvescencc. The calcium sulphate is liltered oil', washed well, and sodium carbonate added to the filtrate till im furtlicr precipitate is produced ; the precipitate is filtered, and the solution of tiie sodium salt evaporated to dryness, first over the free flame and finally on the water-bath. The sodium salt of the diethylaniline meta- sulphonic acid is now converted into the phenol by fusion with caustic soda. The fusion is done in a nickel crucible of 250-c.c. cajiacity, which is heated in an oil-bath. One part of the dry sodium salt is added gradually to a mixture of one part of caustic soda and one-third of a part of water, which is heated to 260-270°. During the addition of the sodium salt the contents of the crucible are well stirred by a thermometer encased in a copper tube. Gloves and spectacles must be worn to avoid accidents due to spirting. When all the sodium salt has been added the temperature is maintained at 270° for five minutes and the mass allowed to cool. The contents of the crucible are, when cold, extracted several times with water acidified with hydro- chloric acid, and the neutralised solution evapoiated to a small bulk, when tiie diethylamidophenol crystallises out. This is filtered at the pmnp and dried on a porous plate. Properlies. — M.P. 14°, B.P. 275-280°; is used for the preparation of Rhodamine B (p. 252). Equatiouf:.- N(CjH5>. U -(- HSO^ H„0 I le-« + NaOH /'SO,Na NaJSO, 1 1 . in-DinUrofoluene. CH, ,^c NO., Kayscr, Zeit. Farb. C'liem., 1903, 32. First nitrating acid Second nitrating acid 100 grams toluene. 175 ,. cone, sulphuric acid (98 c.c). 113 ,, cone, nitric acid, sp. gr. I'-iS (78 c.c). 338 „ cone, sulphuric acid (188 c.c). 113 ,, fuming nitric acid, sp. gr. 1'5 (76 c.c). The tolucni^ is placed in a stout round Hask of about one-litre capacitj', which is fitted with a three-holed rubber stopper, carrying (1) a thermometer reaching nearly to the bottom of the flask, (2) a small funnel, and (3) a glass tube bent at right angles to carr}' oil' the fumes. The first mixture of "nitrating acid" is added through the funnel in small portions at a time, the flask being well PREPARATIONS OF INTERMEDIATE PRODUCTS. 207 gliaken after each addition and the temperature being kept at 60°. When all the acid has been added, the temperature is kept at 60° for half an hour, and the flask well shaken, then allowed to cool. Tlie contents are now transferred to a separating funnel and the acid drawn off. Tlie oil (a mixture of <>- and ^Miitrotolueue) is put back into the flask, and the second " nitrating acid " added slowly. The temperature rises and is kept at 11.5°, if necessary, by warming on the water-lmth. After the whole of the acid has been added, the flask is kept hot and shaken for one hour at frequent intervals. The contents of the flask are now allowed to cool somewhat by standing for fifteen minutes, and poured, while still hot, into a glass funnel, which has been temporarily con- verted into a separating funnel by means of a thick glass rod (or a glass rod fixed to a small stopper), which closes the opening from the top. If an ordinary tap-funnel is used the hot liquid is apt to crack the stopper. The acid is drawn off and the oil is run into a litre of boiling water, and the whole stirred up. Most of the water is poured ofl:', and the last traces of water are separated by the use of the glass funnel previously warmed with hot water. The liquid dinitrotoluene is allowed to crystallise in a dry basin. The yield is 16.5 grams. The nitrating acid, on cooling, deposits a further quantity of dinitrotoluene as crystals (about 12 grams), which are filtered, melted in boiling water, and separated as before. Propertief!. — Long yellow needles; M.P. 71°. The commercial product should be light-coloured and not contam oil. The melting-point should be nearly correct. Usi'. — ?«-Dinitrotoluene is used mostly in the preparation of ?n-toluylene- diamine. Equations. — GS3 G^3 ^.^3 I I -I- HNO3 -^ I J™"2 and I I N0„ (o-nitrotoluene) (^>nitrotoluene). CH3 (2) /XuO '\y CH3 /x I I NO, 12. m-Toluylenediamine. NH., 100 grams m-dinitrotoluene. S ,, cone, hydrochloric acid. 225 „ iron powder. The iron powder is placed in a round flask together with 300 c.c. of water and a little ;)i-dinitrotoluene. The acid is now added and the mixture well 208 SYNTHKTIC PYESTrFFS. sliaken ; a little more diuitrotoluene is added, and the tl.isk heated to 60-70°, if necessary, in order to start the reaction. The nitro-coni pound is added gradually, in small jjortions at a time ; the temperature rises after each addition, and the next portion is not added until the temperature begins to fall. This should not be allowed to rise over SO', the flask being cooled, if necessary, under the tap When the reduction is finished, the mixture is filtered hot at the pump, the iron residue transferred to the flask, and boiled up with water and filtered again. The united filtrates are allowed to cool, when the m-toluyleue- diamiue crystallises out in fine white needles. These are filtered oft', and the filtrate further concentrated, when a second crop of crystals is obtained. If a solution only of »i-toluylenediamine is required, the filtrates may be diluted and tested by standard solution of diazobenzene chloride (see p. 277) in presence of sodium acetate. Froperfies. — Colourless needles soluble in hot water, alcohol, and ether; M.R 99°, B.P. 283-285°. Use. — m-Toluylenediamiue is used in the manufacture of Bismarck brown, many Cotton blacks, and as a " Developer." Eijuaiion. — CH;, CH r^^-^ + OH. -> ,• ■■^™^-' + 4h:,o NO.. nh:. 13. Bi'mpline. Erdmann, Zeit. ang. Cliem., 1893, 163. 100 grams nitrobenzene. 170 „ zinc dust. 105 ,, caustic soda. The caustic soda is dissolved iu 300 c.c. of water, 50 c.c. of methylated spirit, and the nitrobenzene added, the operation being carried on in a round flask of lJ-2-litres capacity. The flask is fitted with a cork, through which passes a glass tube about 2 inches long, by means of which connection is made with a reflux condenser by using a 6-inch length of |-iuch rubber tubing. The zinc dust, which must have been passed through a fine sieve, is now added iu small portions at a time to the mixture, and it is essential that the flask should be thoroughly well shaken after each addition of zinc, and, indeed, throughout the experiment. The zinc dust produces a vigorous reaction and the mixture boils. The mixture is kept boiling by successive additions of zinc, but this should not be added so quickly as to cause the contents of the flask to foam up. The brown colour gruduallj' disaiipears, and when the reduction is complete the contents of the flask should appear greyish white. If this eftect is not produced at this stage, more zinc dust may be added, and the flask hejited on the sand-bath till reduction is complete. The contents of the flask are cooled, diluted with water, ice added, and the whole carefully acidified with hj-dro- chloric acid, tlie temperature not being allowed to rise above 15°. The hydrazobenzene separates out in crusts, which are easily separated from the liquid, and any zinc remaining undissolved, bj* pouring the whole PREPARATIONS OF INTERMEDIATE PRODUCTS. 2O9 through a porcelain funnnl (without paper), and washing the hydrazobenzene with water. This is now converted into benzidine by boiling with 300-400 c.c. of water and adding concentrated hydrochloric acid gradually as long as the latter is absorbed ; finally, the acid solution is allowed to boil for a few minutes longer and the solution of benzidine hydrochloride filtered. To the filtrate sulphuric acid is added, to precipitate the benzidine as sulphate. This is filtered, washed, and boiled with dilute caustic soda solution. The solution of the free base is filtered, and the benzidine crystallises out on cooling, is filtered, and dried on a porous plate. 1 Yield 20-30 grams. Properties. — Benzidine crystallises from hot water in large silky plates ; M.P. 122°. It is tested by titration with standard sodium nitrite solution. Use. — Benzidine is used for the preparation of direct-dyeing cotton colours. Equatiojis. — CfiH-,NO„ CsHsN. (1) ■ " + 3H„ -> I >0 + 3H5O CiHjNO, " CaHsN/ (azoxybenzene). C„H,N. CsHgN (2) ' I >0 + H„ -* 11 + H.,0 CsHjN/ " CbHjN (azobenzene). C^H^N C„H,NH (3) '11 + H„ -♦ I C^HgN ' CsH,NH (hydrazobenzene). CiH^NH _^ CeHjNHo (,jj_j|jg. by molecular change c^jj^NHo (benzidine). 14. ThiocarhaniUde {syiii. DiphenijUhiourea). CS< \NHCsH5 200 grams aniline. 200 ,, carbon bisulphide. 200 ,, absolute alcohol. The aniline, carbon bisulphide (great care to be taken not to bring this in the neighbourhood of a flame), and alcohol are mixed together in a round flask fitted with a reflux condenser, and gently boiled on the water-bath for about ten hours. As sulphuretted hydrogen is evolved, an exit tube mav' be attached to the top of the condenser, leading either to a draught cupboard or into soda-lime. The mass solidifies after a time. When the reaction is finished, the alcohol and excess of carbon bisulphide are distilled oft' on the water-bath (there must be no flame near the receiver !). Water is added, and the crystals are filtered, washed first with very dilute hydro- ' On the large scale, benzidine is jmrilitd by distillation in vaciiu. 14 2IO SYNTHETIC DYESTUFFS. chloric acid, to remove any unchanged aniline, and finally with water. The thiocarbanilide is dried on a porous plate. Yield '200-'2W grams. Propeiiua. — Colourless rhombic plates ; M.P. 151° ; used for the preparatiou of Indigo l)3' Sandmeyer's method (see p. 263). Equation. — NHCH cs., + l'C.hnh:. -i- cs as NHC0H5 15. Benzol chloride. CHCl, I I \/ 50 grams toluene. The toluene is placed in a 100-c.c. round flask with a wide neck, which is fitted with a doutjly-bored stopjier. Through one hule passes the tube of a reflux condenser, and through the other a narrower glass tube (reaching to the bottom of the flask), through which a current of dry chlorine is led. The flask is placed in the sunlight, the toluene heated to boiling, and a current of dry chlorine conducted into it \nitil its weight is increased by 40 grams. (The chlorine may be conveniently prepared by warming a mixture of concentrated hydrochloric acid and powdered potassium bichromate ; it is dried by bubbling through concentrated sulphuric acid). The flask and toluene are weighed before the experiment, and by weighing again after passing the current of chlorine for some time the progress of the chlorination may be observed. In summer the reaction is complete in a few hours, but in winter a much longer time may be necessary. The reaction may be assisted by adding 4 grams of phosphorus pentachloride to the toluene. The crude product is not separated, but is used immediately for the preparation of benzaldehyde (see below). Projierties. — Colourless liquid ; B.P. 2o6°. A/iali/sis. — By determining the boiling-point and, if necessary, the percentage of chlorine. Eqitatiun. — CH, CHCL, /\ /^ ' I I + 2CL, -» 11 + iHCl 16. Benzaldehyde. CEO /\ I I \y 90 grams crude benzal chloride. The crude benzal chloride is transferred to a round flask fitted with a reflux condenser, 500 c.c. of water and 150 grams of precipitated calcium carbonate added, and the mixture heated for four hours in an oil-bath (temperature of bath. PREPARATIONS OF INTERMEDIATE PRODUCTS. 2 I I 130°). (On the Large scale the lienzal chloride is heated in an autoclave with milk of lime.) The contents of the flask are now distilled with steam until no more oil passes over. Before the crude benzaldehyde is purified, the liquid remaining in the flask is filtered while hot and excess of concentrated hydrochloric acid added. On cooling, the benzoic acid, which is formed as a bye-product, separates out in leafy crystals. It is filtered off and recrystallised from hot water. M.P. 121°. The steam distillate is now treated with a concentrated solution of bisulphite of soda (NaHSO.,) until, after long shaking, the greater part of the oil has passed into solution. If crystals of the double compound of benzaldehyde and sodium hydrogen sulphite separate out, water is added until they are dissolved. The aqueous solution is filtered from the oil remaining undissolved, and the filtrate treated witli anhydrous sodium carbonate until an alkaline reaction is obtained. The liquid is then distilled with steam, when pure benzaldehyde passes over, and, after standing, is separated by means of a tap-funnel. It is finally distilled, preferably in a stream of hydrogen. Properties. — Colourless liquid, smelling of bitter almonds; B.P. 179°, sp. gr. I '0504 ; slightly soluble in water. Benzaldehyde is used largely in the preparation of Malachite green ; also benzoic acid and cinnamic acid. Analyds. — (See p. 279.) Equations.- CHCL CHO /\ /\ 1 1 + H.,0 -^11- f 2HC1 V' \/ CHO CHOCNaHSOj) /\ /X f 1 + NaHSO, -^ 1 1 \/ \/ CH0(NaHB03) CHO ,/\ /\ 1 J + NaXOs -^ 1 I + NaHCOs -1- NajSOs 17. m -DinifrophenoJ. OH NO, Engelhardt and Latschinow, Ber., 1870, iii. 97. Clemm, J.pr. Ghein., 1870, [2], 1. 145, 170. 100 grams chlorodinitrobenzene, CI : (NO.,).i= 1:2:4. 125 ,, sodium carbonate (anhydrous). The sodium carbonate is dissolved in 1120 c.c. water contained in a round flask, the chlorodinitrobenzene added, and the whole boiled for twenty-four hours, the flask being fitted with a reflux condenser. After this time the whole of the oil will have gone into solution. The solution is acidified with hydrochloric acid, when the dinitrophenol separates out; this is filtered at the pump and dried in the air. Yield 91 grams. RYNTHF.Tir DYESTUFFP. Properties. — m-Dinitrophcnol crystallises from water in pale yellow tables; M.P. 114°. On reduction it vieMs dianiidophenol. which is used as a photo- graphic developer (amidol). Dinitrophenol is used largely in the preparation of " Sulphur blacks." Eijuation. CI ONa I r"-- + Na.,C03 -» I |^"= + NaCl + CO., NO, NO, ONa OH I i^°- + HCl -* I r'^"^ + NaCl NO., NO, CHAPTER XXVIII. PREPARATIONS OF INTERMEDIATE PRODUCTS. II. NAPHTHALENE SERIES. 18. Naphthale7ie-fi-sul2Jhonic acid. 100 grams naphthalene. 120 ,, cone, sulphuric acid (67 c.c). The acid is warmed to 100° in a round flask, and the finely -ground naphthalene added gradually, the flaslv being well shaken. The mixture is now heated (without condenser) in an oil-bath to 160-170° for twelve hours. After cooling, the sulphonation mixture is poured into 1| litres of water, heated to boiling, and milk of lime added until an alkaline reaction is obtained. (The amount of quicklime is calculated from the sulphuric acid, and is slaked with hot water.) The mixture is at once filtered through cloth, the filter-cloth is squeezed out into another dish, the liquid, if turbid, being filtered and added to the main quantity. The precipitated calcium sulphate is boiled up with 1 litre of water, filtered, and pressed. The united filtrates are evaporated down to a small bulk and allowed to cool. After standing overnight the calcium salt of the sulphonic acid crystallises out and is filtered at the pump. ■ It is now dis- solved in hot water, and a solution of sodium carbonate added till a filtered portion (10 c.c.) gives no further precipitate with sodium carbonate. (The weight of anhydrous sodium carbonate to be dissolved is calculated, assuming a theoretical yield of naphthalene sulphonic acid.) The precipitated calcium carbonate is now filtered at the pump, and the sodium salt evaporated till crystals begin to separate out. After standing overnight the crystals are filtered off" and the filtrate further evaporated, when, after cooling and standing, a second crop may be obtained, which is added to the first, and the whole dried on the water-bath. Yield 120-UO grams. Properties. — The acid forms non -deliquescent plates. Equation. — I I ] + H,so, -> I I r^^ 2 14 SYNTHETIC DYESTUFFS. 19. P-Naphthol. 100 grams sodium naphthalene-Zi-sulphonate. 300 „ powdered caustic soda. Tiie caustic soda, together witli 30 c.c. of water, is placed in a large copper or nickel crucil)le and the mi.\ture heated to 280°. The thermometer is enclosed iu a copper or nickel tube closed at one end and containing a little oil. A large cork is fitted to the open end of the tube, whereby the latter may be con- veniently held and used as a stirrer. In this, as in all melting operations with caustic alkali, the eyes must be protected by glasses and the hands by thick gloves. The tinely powdered ^-salt is now added as quickly as possible, with constant stirring, but care must be taken that the temperature does not fall below 260°. When all is in, the temperature is raised to 320°, and the reaction takes place at 310-320°. The mass froths and steam is evolved, and when the mass becomes quite liquid the reaction is complete. The length of time for which the fusion is kept at 310-320° is about five minutes. The top layer of the melt, which is darker than the lower one and contains the sodium naphtholate, is now poured on to a copper plate with upturned edges, and, after cooling, the mass is broken up and dissolved in water. The naphthol is precipitated with concen- trated hydrochloric acid (in the draught chamber). Ou the large scale the pre- cipitation is sometimes brought about with a stream of carbon dioxide. After cooling, the /3-naphthol is filtered oft', dried, and distilled in vartto (see ]j. 1S7). Yield 50-55 grams. Propfiiii's. — Colourless, crystalline solid ; M.P. 123°, B.P. 286, sp. gr. 1"217 ; difficultly soluble in water (in 1000 parts cold and 75 parts boiling); easily soluble in organic solvents. Use. /i- Naphthol is used largely iu the prejiaration of azo- and other dyes ; also in the production of " para-reds," etc., on the fibre. For analysis, see page 280. /\/\0Na + 2NaOH ■* '\/\/' + Na.SO, !H.,0 ,ONa _^ ,/\, '^.OH + HCl "^ ' X J f NaCl 20. p-Naphtho'-d-xiiliihdulc ari.l (.SduiHVr's salt). K.P. 7098'<<. 100 grams ^-naphthol. 200 „ cone, sulphuric acid (111 c.c). PREPARATIONS OF INTERMEDIATE PRODUCTS. 2 I 5 The /3-naphthol is finely ground and gradually added to the sulphuric acid, which has been previously warmed to 30— iO° in a round flask of about 400-c.c. capacity. The mixture is now heated on the water-bath to 100° for eight hours. The product is dissolved in about a litre of water and saturated with common salt. The sodium salt of the naphthol sulphonic acid separates out, and, after standing overnight, is filtered, washed well with saturated salt solution till free from. acid, and dried. The sodium salt of the isomeric acid (" Bayer's acid," OH : SO3H = 2:8), which is simultaneously formed, remains in the filtrate. Yield 100 grams. Properties. — -The sodium salt crystallises with two molecules of water. It is tested by titration with solution of potassium bromate. Use. — Schaffer's salt is used largely for the prepai'ation of azo-dyes ; also for the preparation of " eikonogen " (CiuHj.(0H)(S03H).(N0) = 2:6:1), used as a photographic developer. Equation. i I |0H + HSO, -* __^ I j"« + HP 21. (i-Naphthol-S : 0-disulphonic acid (" R salt"). ^0H E.P. 70978*; DP 33_9i684 100 grams /3-naphthol. 400 ,, cone, sulphuric acid (222 c.c). The sulphuric acid is placed in a round flask of one-litre capacity and warmed on a sand-bath to 125°. The naphthol, finely powdered, is added fairly quickly, and the mixture kept at 125-126° for five to six hours. It is now poured into water and neutralised with milk of lime. The calcium sulphate is filtered oflF, boiled up again with hot water, and again filtered, both filtrates being united. A solution of sodium carbonate is now added till no further precipitate is obtained, and the calcium carbonate filtered off. The filtrate is saturated with salt, and the R salt separates out as a j-ellowish flocculent pi-ecipitate, which is filtered, washed with concentrated salt solution, and dried. Yield about 200 grams, 100 per cent. The product should be 80 per cent. (mol. wt. 348). Properties. — The disodiiim salt is easily soluble in water, nearly insoluble in alcohol, and combines very easily with diazo-solutions. R salt is tested with a standard solution of potassium bromate. Use. — It is mostly used for the preparation of azo-dyes for wool. Equation. — OH , „.cr ort 2l6 SYNTHETIC DYKSTUFFS. 22. a-Nitronaphthaleiie, C,oH;NOo Witt, Chem. Ind., lt!87, x. 216. NO., 100 grams naphthalene. 80 „ cone, nitric acid, sp. gr. 1 •! (57 c.c). 100 ,, cone, sulphuric acid (5G c.c.). Tiie acids are nii.xed as in the preparation of nitrobenzene, and transferred to a round flask of about 500-c.c. ca])acity. The naphthalene, which must have been finely ground in a mill (a cofTee-mill answers the purpose), is added in small quantities at a time, the flask being well shaken and cooled after each addition. Tlie temperature is kept at 45-50". After all tlie naphthalene has been added, the mixture is warmed to 55-GO" and poured into cold water. The nitroiiaphtlialene sinks to the bottom and the acid is poured off'. The solid cake is boiled up with water and the water poured away. Tlie oil is now transferred to a lari,'e flask and subjected to steam distillation, whereby a little unatUicked naphthalene is driven over and collects in the distillate. The contents of the flask are now poured into a large (juantity of cold water, which is constantly stirred. The granulated nitronaphthalene is filtered off and dried in the air. Yield 1 30 grams. Properiies. — Light yellow solid, crystallising from alcohol in long needles; M.P. 61°, B.P. 304°, sp. gr. at 4°, 1-331. a-Nitronaphthalene must have the correct melting-point and should not contain naphthalene (shown by distillation with steam). Use. — It is used almost entirely for the manufacture of a-na|)hthylamine. K(iuati()n. — H; OH NO, \/ 23. a-Xonate ; it should be about 4 jier cent, and contain 75-80 grams of the naphthol sulphonic acid. The presence of the small quantity of red colour in the solution is not detrimental to the shade of even a blue azo-dye prepared from it, as, owing to its solubility, the Carmoisine passes away in the filtrate. PREPARATIONS OF INTERMEDIATE PRODUCTS. 219 Another method of preparation of this acid consists in heating a mixture of 100 grams sodium naphthionate, 100 grams caustic soda, and 100 c.o. water in an autoclave for eight to ten hours to 240-260°. After cooling, the pro- duct is dissolved in 750 c.c. of hot water and neutralised with hydrochloric acid. The solution is now saturated with salt, when the sodium salt of the naphthol sulphonic acid separates out in white crystals and is filtered and dried (D.P. 46,307ss). Propertii's. — Both the free acid and its salts are very soluble in water. The sodium salt ,0H ^■^ gQ^"^ ""l^ l^'^- + 2H2O 30. Amidonaphtliol sulplmnic arid y. OH K.P. 15,176'*", 1G,699«''. 50 grams /3-naphthylamine disulphonic acid (i. 42 ,, j)owdered caustic soda. Tiic caustic soda is dissolved in 50 c.c. of water and placed in an autoclave. The amido-G salt is well stirred in, the lid screwed on, and tiio vessel heated for si.\ hours to 190-195°. When the autoclave is (juite cold it is opened, and the contents dissolved in water and acidified with hydrociiloric acid in the draugiit chamber. On cooling, the y acid crystallises out and is filtered and dried. Properties. — The acitl is difficultly soluble in water. Tiie alkali salts dissolve easily with blue fluorescence. The acid is tested by titration with standard solution of diazobenzeue chloride in alkaline solution (sodium carbonate). PREPARATIONS OF INTERMEDIATE PRODUCTS. 223 It is used very largely in the manufacture of azo-dyes, especially Cotton blacks. EqiiatioH. — SO3H ONa r Y F^^ + 4NaOH -> -,-„f 1 |NHn + N£uS03 + 3H,0 ^°^\y\y SO,Na^\/ (On acidifying, the free acid is obtained.) 31. Anthraquinone. CO Cohen, Practical Organic Chemistry. 10 grams anthracene (pure). 120 c.c. glacial acetic acid. 20 grams chromium trioxide dissolved in 15 c.c. water and then 75 c.c. glacial acetic acid added. The method used technically for the oxidation of anthracene, viz., with potassium bichromate and sulphuric acid in aqueous suspension, cannot be conveniently imitated in the laboratorj', as, in order to obtain the anthracene in a sufficiently finely divided condition, it is sublimed in a current of superheated steam and condensed by fine jets of water. The finely powdered pure anthracene on the market is unattacked by this oxidising agent unless it undergoes the above process ; for this reason the following method is more conveniently employed : — The anthracene is dissolved in the acetic acid by boiling them together in a romid flask (half-litre) with upright condenser over wire gauze. The solution of chromium trioxide is then dropped in from a tap-funnel, pushed into the top end of the condenser, whilst the liquid is kept boiling. The operation should last about an hour. The solution becomes a deep green. It is allowed to cool, and is poured into water (500 c.c), which precipitates the anthraquinone in the form of a brown powder. After standing an hour, it is filtered through a large folded filter, washed with a little hot water, then with warm dilute caustic soda and water again. Yield 10-12 grams. A portion of the dry substance may be purified by sublimation. It is placed (2-3 grams) on a large watch-glass, which is heated on the sand-bath over a very small flame. The watch-glass is covered with a sheet of filter-paper, which is kept flat by a funnel placed above. After five minutes or so pale yellow, needle-shaped crystals of anthraquinone will have sublimed on to the filter-paper. Properties.— XeWoss needles; M.P. 277°; sublimes at 250°; B.P. 382°; insoluble in water, soluble in acetic acid, less soluble in benzene and other organic solvents. Equation. — • CH I I I I + 30 -^ CH 2 24 SYNTHETIC PYESTrFFS. '^^2. Anlhraquinone suifihoitic acid. CO 100 grains anthraiiuinoue. 100 ,, fumiui,' sulphuric acid, 45 to 50 per cent. SOj. The acid is melted, if necessary, and the finely powdered anthraquinone added. The mixture, which is contained in a round flask, is gradually lieated in an oil-bath, so that at the end of one hour the temperature has reached 1C0°. The mixture is now slowly and carefully poured into hot water, the solution boiled for some time, and the unchanged anthraquinone filtered oH' at the puni]). This amounts to 20-25 grams. The filtrate is neutralised witli caiustic soda and allowed to cool, when the greater part of the sodium anthraipiinone sulphonate crystallises out. (This is the so-called "silver salt.") A second crop of crystals may be obtained by further concentration of the filtrate. The final filtrate contains the sodium salt of anthraquinone disulphonic acid, which ma3' be obtained, mixed with sodium sulphate, by evaporating to dryness. ProperficK. — The sodium salt crystallises from water with one molecule of water of crystallisation, having the formula C,^H-(SO Na)0., + H.,0. On melting with caustic alkali it is converted into alizarine. Equation. — CO + H.JSOj -> I I I r°»" + H.jO CO CHAPTER XXIX. PREPARATION OF DYESTUFFS. 1. Fast green (dinitrosoresorcin). O II NOH Goldschmidt and Strauss, Ber., 1887, xx. 1607. Kostanecki, Ber., 1887, xx. 3137. J.S.O.I., 1890, 1126. 20 grains resorcinol. 45 ,, cone, hydrochloric acid (39 c.c). 25'5 ,, sodium nitrite. The resorcinol is dissolved in 800 c.c. of water and the hydrochloric acid added, together with 100 grams of common salt. Ice is added till the tem- perature is 0°, and into this solution, which is stirred mechanically, the sodium nitrite, dissolved in 100 c.c. of water, is allowed to flow very slowly, the tem- perature not being allowed to rise above 8°. This takes about half an hour. When all the nitrite has been added, the liquid should show a faintly acid reaction. After standing for one hour, the brownish-yellow precipitate is filtered, washed with ice-cold water, and the paste dried on a porous plate. Yield 36 grams. Properties. — Greyish-brown powder, soluble in hot water. Dyes iron- mordanted cotton green ; iron-mordanted wool dark green. Equation. — OH OH /\ /\no I loH + -^HNO'^ - l^J?H + '"^^ NO (resorcinol). (dinitrosoresorcin). O II /\-, = NOH NOH For the explanation of this formula, see page 42. IS 2 26 SYNTHKTIC DYKSTUFFS. 2. Naphthol ijellmo S. SO,K,-^^/^lfO, •^Y Y r *^ NO, E.P. 5305"''; A.P. 2-25,10SS"; D.l'. 10,785"-'; F.l'. 134,632'"'; E.P. 11,3188". 100 yranis a-iiaphtliol. •100 ,, cone, sulphuric acid (222 c.c). 200 ,, cone, nitric acid (143 c.c). The sulphuric acid is warmed to 100° in a round flask, and tlie finelj' powdered naphthol added gradually. The temperature is now raised to 120°, and kept at this point for tliree to four hours. The sulphonation mixture is then poured into 600 c.c. of water and stirred mechanically. As soon as the temperature is about 30°, the nitric acid is added very slowly drop by drop through a tap-funnel, the teini)erature not being allowed to rise above 45°. The dinitronaphtiiol monosulplionic acid, which separates out after standing, is filtei'ed at the pump, waslieil witli saturated salt solution till free from acid, and mi.xed with boiling water. Potassium carbonate is now added till an alkaline reaction is obtained, and, after cooling, the precipitated potassium salt filtereii, and dried on a porous plate. Properties. — Orange yellow jiowder. Dyes wool and silk yellow from an acid bath. Analysis.— \Nith Night blue (p. 308). Equation. — OH OH ^^ + JHNO+HSO, -> SO,H^^|/\nO., h 3H.,0 \/\y NO., Najilitlicil vflluw 8 (free acid). 3. Chrtjsoidine R. NH, ^^N : N^^NHo.HCl I CHj Ber., 1877, x. 213, 350, 388, 654. 9'3 grams aniline. 30 c.c. cone, liydrochloric acid. 7'2 grams sodium nitrite (or 100 c.c. of a normal solution). 12'5 ,, ?«e/rt-toluylenedianiiue (or an equivalent solution). 'i'he aniline is mixed with about 200 c.c. of water in a heavy beaker and ice added. The acid is poured in and the solution diazotised by adding slowdy a solution of 7'2 grams of sodium nitrite, the whole being continually stirred. PREPARATION OF DYESTUFFS. 227 The nitrite solution is added in small portions at a time, and after each addition a drop is withdrawn from the solution and placed on iodide-starch paper ; if a reaction is obtained the mixture is stirred further, and tests are frequently made till no blue coloration is seen on the paper. The next portion of nitrite solution may now be added. Towards the end the nitrite is added in very small portions, and the solution is continuallj' tested so as to avoid any excess of this reagent. If the diazotisation has been properly carried out, no smell of nitrous gases should have been detected, and the test-paper should be only faintly coloured blue by the solution after the latter has stood for five minutes. If too much nitrite is present, a fgw drops of aniline may be added. The temperature throughout the diazotisation must be kept below 5°, by adding more ice if necessary, and the solution of the diazo-salt must be perfectly clear. In order to combine it with the toluylenediamine, the latter is dissolved in about 400 c.c. of cold water ; if the diamine is already in solution, it must be rendered neutral with hydrochloric acid, if necessary, and diluted to 400 c.c. This is placed in a thick beaker or basin and agitated by a mechanical stirrer. The diazo-solution is then poured in and the mixture allowed to stir for some time. A few drops are now withdrawn by a pipette, put into a test-tube, and shaken with a few grams of salt till the colouring matter is precipitated. A little of this is dropped on filter-paper, when a colourless rim spreads from the drop of colour. A drop of diazo-solution is now placed on one side of this rim, so as to mis with it, and a brownish-yellow line should appear at the junction of the two liquids, showing the presence of an excess of 7«-toluylenediamine. In case this reaction is not obtained, another droji is tested in like manner with a solution of the diamine, and if a reaction is here obtained an excess of diazo- solution is present, and ?/i-toluylenediamine solution must be added until a slight excess is present. If a reaction is obtained in both the above cases, the com- bination is not complete and the stirring must be continued. A solution of sodium acetate may also be added in order to neutralise the excess of mineral acid present. The colouring matter is now precipitated from the solution by adding common salt gradually. Tests are continually made by allowing a drop of the mixture to fall on filter-paper ; at first the rim is strongly coloured, but as the salt is added more and more colouring matter is precipitated, until at last the rim is only faintly coloured orange. The chrysoidine hydrochloride is filtered, dried, and ground. Properties. — Yellowish-brown powder, soluble in water with a yellow colour. Dyes wool, silk, and tannin-mordanted cotton orange. E(iuatioiif. — CI ^^* <^~^NH., r NaN0,+ 2HCl -* <^ ^N ; N -f NaCU 2H.,0 (aniline). (diazonium chloride). NHo NH, I " I ~\ ~ I CH, CH3 ?/i-tolaylenediamine. (Chrysoidine R), NH,.HC1 SYNTH KTIC DYESTUFFS. 4. Orange II. OH SO:^a<^ ynt : N< ~ o Jliihlhiiuser., DimiL jiol. J., 1887, cclxiv. 187, 238 j J.S.C.I., 1887, 591. I'aul, Z. fur aiKj. CItem., 1896, 686. 17 '3 grams sulphaiiilic acid. 7"2 ,, sodium nitrite. 14-4 „ /i-uaphtbol. Tlie suljilianilicacid is dissolved in water by careful addition of caustic soda solution (on the large scale, nsing the crude product, the solution is boiled for a few minutes in order to drive oft' traces of aniline and then filtered). Ice is added till the temperature is 5°, the volume of the whole being about 500 c.c. 30 c.c. of concentrated hydroubloric acid are poured in, and then the sodium nitrite, dissolved in a small (luantity of water (or 100 c.c. of a normal solution), added slowly. Tests are made from time to time with starcli-iodide paper, and a slightly blue coloration should be obtained when all the nitrite has been added. The diazo-compound separates out in fine white needles. {Noti-'. — This should never be filtered and allowed to dry, as it is extremely explosive.) The /3-iuiphthol is dissolved by heating it with a solution of 45 grams of caustic soda in 15 c.c. of water, and the sodium naphtholate solution thus formed is poured into 160 c.c. of cold water, and this cooled, if necessary, to about 15°. This solution is stirred bj' a mechanical stirrer, and the diazo-solution (or diazo-compound in suspension) run in gradually. When the whole of the diazo-solution has been added, the mass should show a weak alkaline reaction (test with brilliant-yellow paper), and practically no excess of either component (diazo-compound or /J-naphthol) should be present. Although it is usual to leave a slight excess of the phenol or amine in the preparation of azo-dyes, yet in this case an excess of />nuphthol has a bad eftect on the shade of the dye produced, and it is better to leave a slight excess of diazo-solution in the mixture. The mass is stirred for an hour longer, when nearly the whole of the colouring matter will have separated out. A little salt solution is added, so as to precipitate nearly the whole of the dye. A test on filter-paper should show a pale orange rim. It is now filtered at the pump, dried at 80°, and ground. Yield 34 grams. Properties. — Bright orange powder, soluble in water with orange colour. Dyes wool orange from an acid bath. Analysis. — With standard solution of titanous chloride (see p. 302). Equatio7is. — >NHj + NaN0.,-^■2HCl -* Osi (suljihanilic acid). (diazosulphanilic acid). ONa OH I i I - ' OjS/~^N i N -I- /~\ -* S03Na<^^N : N^^ (Orange II.). PREPARATION OF DYESTUFFS. 229 5. Fast red B (Bordeaux B). OH SOjITa o o I SO.,Na E.P. 1715"S; A.P. 251,164; D.P. 3229'S; F.P. 124,811. 14-3 grams a-naphthylamine 7'2 ,, sodium nitrite. 35 „ " R salt " The naphthj'lamine is dissolved iu 300 c.c. of hot water and 10 c.c. of concen- trated hydrochloric acid. The clear solution is cooled by addition of ice, and then 20 c.c. of concentrated hydrochloric acid added ; the temperature must be reduced to 0-4°. The sodium nitrite (dissolved in a little water) is now poured in fairly quickly, and a slightly brown coloured sulution of the diazo-salt is obtained. This should be perfectly clear ; if a brown precipitate of diazoaraidonaphthalene appears, a fresh solution nnist be prepared, adding, if necessary, 25 c.c. of acid instead of 20 c.c. This diazo-solution is now added slowly to the " R salt " solu- tion, which has been prepared by dissolving 35 grams of " R salt" (this quantity is calculated for the pure substance — raol. \vt. 348 ; if a less pure " R salt " is used, a proportionally greater quantity must be taken) in 400 c.c. of water, adding 8'5 grams of caustic soda and cooling to 15°. During the addition the whole is well stirred mechanically, and an alkaline reaction and excess of " R salt " must be detected when the combination is finished. After stirring for one hour the colour is heated to 80°, salt added until the colouring matter is nearly all precipitated, when it is filtered, dried, and ground. Yield 50-55 grams. Properties. — Brown powder, dissolving in water with magenta-red colour. Dyes wool red from an acid bath. Equation. — CI ■NH., ^~^N : N ■ -I- NaNO.,4-2HCl -* ^— / + NaCl-h2H.,0 (a-naphthylamiue). OH SO,Na OH SOjNa o - <_> o <_> I I SOjNa SOjNa (Fast red B). 230 SYNTHKTIC DYESTDFFS. 6. Faff red A (Roccellinc). OH L SO^Nav >N : N \ )> K.P. 786"*; A.P. 204.799; D.P. 5411"«; F.P. 123,148"«. 24'5 grams sodium naphthiomxte, lUO per cent. 7'2 „ sodium nitrite. 1.5 ,, /3-naphthol. The above quantity of sodium iiaphthiouate is calculated for tiie pure substance (raol. \vt. = 245). If material of less strength than this is used, a proportionally larger amount must, of course, be taken. It is dissolved in cold water and diazotiscd exactly as described on p. 218. The diazo- conipound is filtered and mixed with water to a thin cream. This is poured slowly into the /3-naphthol solution, which is stirred by a mechanical stirrer, and prepared by heatinj,' the naphthol with a solution of 4'5 grams of caustic soda in 1-5 c.c. of water and pouring into 160 c.c. of cold water. The solution of sodiinii y3-naplitliolate should not be above 15°. When the whole of the diazo-compound has been added, a slight excess of /3-uaphthol should be detected (by salting out a few drops in a test-tube, pouring a drop on paper, and testing the rim with a diazo-solution). and an alkaline reaction should be obtained with brilliant-yellow paper. After an hour's stirring the colour is heated to 80°, salt added until nearly the whole of the colouring matter is precipitated, and then filtered, dried, and ground. Properties. — Brownish-red powder, dissolving in hot water with browu-red colour. Dyes wool red from an acid bath. Equaliotis.- SO ,Na<^>: NHl, + NaN0., + 2HCl N :N - L^NaCl r-JH.,0 (sodium naphthionate). O / SO. ONa <:> <_> (sodium /3-naphtholate). (diazo-compound ). OH _ l_ SOjNa/ \N:N<(' \ o (Fast red A). 7. Chrijsamine G. COONa l_ HO/ \n : N. E.P. 9162S' ; .\.P. 329,638; D.P. 31,658s^ COONa N:N<'^ \0H lS-4 grams benzidine. 32 „ salicylic acid. PREPARATION OF DYESTUFFS. The benzidine is dissolved in 300 c.c. of hot water containing 20 c.c. of con- centrated hydrochloric acid ; the solution is cooled with ice to 5°, 30 c.c. of concentrated hydrochloric acid added, and the solution tetrazotised with 14'4 grams of sodium nitrite dissolved in a little water. The solution must be clear and give a faint blue colour with iodide-stai'ch paper. The salicylic acid is dis- solved in 200 c.c. of cold water with addition of 9 "5 grams of caustic soda, and the tetrazo-solution poured into it whilst stirring mechanically. The whole is well stirred for a day, during which time a solution of 12 grams of caustic soda is very slowly added. At the end of this time no tetrazo-compouud should be present (test with R salt) ; but if the combination is not quite complete, it must be stirred during the following day. The solution must also show an alkaline reaction. The colouring matter is entirely precipitated, so that no salt is added, and it is filtered cold, dried at 40-50°, and ground. Properties. — Yellowish-brown powder, sparingly soluble in water with brownish-yellow colour. Dyes unmordanted cotton yellow from a soap-bath. Equation^.— (1) |<(~>NH., + 2NaNO., + 4HCl CI I >N IN 2NaCl + 4H.,0 (benzidine). CI I •N = N (2) / NN = N <^ ONa ONa (tetrazobenzidine chloride). COONa /"> : N<" CI |<;_>N : N<;_>i OH OH 2NaCl COONa (sodium salicylate) (2 mols.). COONa (Chrysamiue G). 8. Benzopurpurine J^B. CH, CH. |/\^N:N<_>-<3n:N|. NHo 1 I SO.,Na SOjNa E.P. 3803*5; A.P. 329,632; D.P. 35,6158'; pp 167,876. 21 '2 grams tolidine. 54 „ sodium naphthionate, 100 per cent. The tolidine is dissolved in 300 c.c. of hot water containing 20 c.c. of con- centrated hydrochloric acid, cooled with ice to 5°, 30 c.c. of concentrated hydro- chloric acid added, and the solution diazotised with a solution of 14-4 grams of sodium nitrite in a little water. The diazo-solution must be quite clear and o-ive a slight reaction with iodide-starch paper. This is now poured into a 2y. SYNTHETIC DYESTUFFS. cold mixture of 54 grams of sodium naphthionate and 100 c.c. of water (the naphtliionate is mostly undissolved), and the mixture stirred mechanically for two (or more) days. After tlie lirst half-hour's stirring a solution of 35 grams of sodium carbonate (Na^.COj) is added, a few drops at a time, so that the whole has been used by the end of the second day. On the next day the colouring matter is heated to 80° and a little salt added, so that the solution remains slightly yellow in colour. The precipitated colour is filtered, dried, and ground. Projieiiies. — Brown powder, dissolving in water with brownish-red colour. Dyes cotton direct from an alkaline bath, red. Analysis with standard solution of titanous chloride (see p. 304). (1) Equations.- CH3 I CHi (tolidine). \ >N ; N I \ (tetrazotolidinc chloride). + iNaCl 4H:0 (2) CH, CI N IN SO,Na v/\ I I (sodium naphthionate) (2 mols.). CHj SOjNa A\ NH, NK. i/\7\ I I I CH^ SOsNa (Bcnzopurpurine 4B). 9. Diamine fast red. 2NaCl + 2NaHCO, COONa OH<^^N : N<^~^-<^^N : N- ;SO,,Na PREPARATIOM OF DYESTUFFS. 233 E.P. 16,69989; D.P. 55,64889. 18*4 grams benzidine. 14*4 „ salicylic acid. 25 ,, y acid. The benzidine is tetrazotised as described on p. 231, and the clear solution added to a cold solution of 14-4 grams of salicylic acid in 45 grams of sodium carbonate (Na^COj) and 500 c.c. of water. This mixture is stirred for two to four hours, when the formation of the intermediate product is complete, and no free tetrazo-solution can be detected in solution. The mixture is now acidified carefully with hydrochloric acid, so that a slightly acid reaction is obtained ; a solution of 14 grams of sodium acetate (CHgOoNa.SH.iO) added, and finally a neutral solution of 25 grams of y acid in 11 grams of sodium carbonate (if this is alkaline, it must be neutralised with a few drops of acetic acid). The mixture is well stirred for several hours, when the combination should be complete. A little more sodium acetate may be added in case it is not, and the whole stirred longer. The colouring matter is now made alkaline with sodium carbonate solution, heated to 80°, and salt added till only a faint yellowish colour remains in solution. It is filtered, dried, and ground. Properties. — Brownish-red powder, dissolving in water with red colour. Dyes unmordanted cotton and chromed wool a fast red. Equations.- (1) /"\nh„ (2) >NH2 (benzidine). - /°^ / \n i N CI ,0. CI 2NaNO., + 4HCl '<^>NIN OH _^ |/^,COONa (sodium salicylate). <->N:N<; + NaoCO, + 2NaCl + 4H„0 '<:> CO I -0 + 2NaCl + NaHC03 (intermediate product). o OH OH CO + NH./ Y 1 ^ ^^IJsO^Na (y acid). nh/ Y ^ OH COOH (Diamine fast red). On adding sodium carbonate to this, the COOH group becomes COONa. 234 SYNTHETIC DYESTUFFS. NH., OH 10. /!>'),:ms/.,/ I.hf. OCH., OCH, SO,Na I I SO.Na :_>-<_>-^..^.- OH NH. SO,Na E.P. 1742^1; A.P. 464,135; D.P. 74,59:5; F.P. 201,770. 12'2 grams dianisidine. 35 ,, " H acid " (acid sodiuin salt, niol. wt. 341). The dianisidine is dissolved in 10 c.c. of concentrated Indrochloric acid and about 200 c.c. of boiling water. The solution is cooled to 5° with ice, 20 c.c. of concentrated hydrochloric acid added, and then a solution of 7 '2 grams of sodium nitrite slowly poured in till a blue reaction is obtained witii iodide-starch paper. The clear tetrazo-solution is added slowly to a cold solution of 35 grams of H acid in 35 grams of sodium carbonate (Na.,C03) and 400 c.c. of water. When all is added, an alkaline reaction mnsl be shown by the mi.xture and excess of II acid must be present. After stirring for an hour the colour is heated to 80°, salt added till only a reddish-blue colour remains in .solution, and the solution is filtered, dried, and ground. Pniperties. — Bluish-grey powder, dissolving in water with a blue colour. Dyes cotton dii'ect from an alkaline batii. Equations. — OCH, i >NH.. + 2NaN0.,-t JHCl '<:> OCH, (dianisidine). OCH, J <>:n -» •2NaCl + 4H,0 O'CH,^^ (tetr izodianisidine chloride). OCH CI CI / /~\n ;n SO:,Na OH NH, OH NH, /\^\' SO,,Nal.^l^SO;,Na ("II acid") (2 nicls.). OCH OH NH, -N • N- ^ "■ ■^^- ' SO„Na'\/l .^0,Na OCH, (Benzo sky blue). + JNaCl + JNaHCO. PREPARATION OF DYESTUFFS 235 11. Diamine blade RU. OH OH E.P. 16,699S'' ; D.P. 55,6488'-'. 18'4 grams l)enzidiue. 50 „ "y acid" (amidonaphthol sulphouic acid y, NH. : OH : SO3H = 2:8:6; mol. \vt. 239). The benzidine is tetrazotised as in the preparation of Chrysamine G, and the solution is added slowly to a cold solution of 50 grams of y acid in 60 grams of sodium carbonate and 500 c.c. of water. The y acid solution must be very well stirred during the addition, so as to avoid any part of the solution becoming acid, as in this case some of the tetrazo-compound may combine in the ortho- position to the amido-group, forming a little Diamine violet, which would redden the shade of the finished colour. At the end an alkaline reaction must be obtained and an excess of y acid must be present. After stirring for an hour the colouring matter is heated to 80°, salted till only a reddish-black colour remains in solution, filtered, dried and ground. Properties;. — Black powder giving a violet black solution. Dyes unmordanted cotton greyish violet; after diazotisation on the fibre and combination with ^-naphthol or ??j-phenylenediamine, gives a deep blue or black fast to washing, light, alkalies, and acids. Equations. — (1) CI |<~>H3 lO^""^^ _ + 2NaN02+4HCl ^ ' _ -I- 2iraClH-4H,0 \ )>NH., / \n:n CI (benzidine). (tetrazobeuzidine chloride). (2) 01 N IN 'O-j \ 01 ^_^ SO,Na/\/\lTH: /_>-N : N_l I /^^ ~ OH + 2NaCl + 2NaHCO, I OH < >-N : N-'^/\nH, ^— ^ SO,,Na\y'\y' (Diamine black RO). 236 SYNTHETIC DYESTUFFS. Diamine violet N [C] is formed by the combination of the above constituents in acid solution ; its formula is NHo 0H<_> SO^a (Diamine violet JS). 12. Naphihol hlue-blm-k. _^ NH, OH NO./ N-N : N-, -N : N- ^— ^ SO^Na'^'x^SOsNa ^— E.P. 6972^1; A.P. 480,326; D.P. 65,651'-"; F.P., fourth addition to 201,770. 7 grams j) nitraniline. sodium nitrite. " H acid " (acid sodium salt of 1 : S-amido- n:xplithol-3 : 6-disulphonic acid), aniline, sodium nitrite. The ^>uitraniline is dissolved by boiling with 20 c.c. concentrated hydrochloric acid and 20 c.c. of water. After cooling, the solution is poured into 200 c.c. of water and ice added till the temperature is 10°. The sodiiun nitrite (36 grams), dissolved in a little water, is now added all at once, and the whole well stirred. A reaction must be obtained with iodide-starch paper. If the diazotisation has been properly carried out, no precipitation of the diazoamido-compound should occur. The diazo-solution is now poured into a neutral solution of "H acid," made by dissolving 17'05 grams (mol. wt. = 341) in 200 c.c. of water with addition of sodium carbonate solution, and carefully neutralising any excess of alkali with hydrochloric acid. The temperature of this solution should be 15°, and during the combination the whole is stirred mechanically. After stirring for half an hour the bluish-red solution is carefully neutralised with aqueous sodium carbonate, and, when neutral, a solution of 15 grams of sodium carbonate is further added. To this blue solution is now added a solution of diazobcnzeue chloride prepared from 4 65 grams of aniline, 15 c.c. of concentrated hydrochloric acid, and 36 grams of sodium nitrite, as described on page 226, and the whole stirred for an hour longer. The mixture must show an alkaline reaction, and when finished is heated to 80° and salted until nearly the whole of the colouring matter is precipitated ; this is filtered, dried, and ground. 3-6 7 05 4-65 3-6 PREPARATION OF BYESTUFFS. 1^1 Properties. — Dark powder, dissolving in water and giving a dark blue solution. Dyes wool blue-black in an alkaline bath. Equations. — _ ,C1 NH., OH N0„<^ \n : N + r 1^1 ('" ^'^''^ solution). (diazo-^-nitraniline (H acid), chloride). NHe OH -*• NO./~V-N : N-r^/ ^ + HCl CI OH NH, _ S0.;H\ a /SOoNa ^- (diazobenzene chloride). OH NH, / N-N: N-,/^,^^-N ;N-<(' \nO„ + NaCl + 2NaHC03 ^— ^ SOjNa'x^' ./WNa — (Xaphthol blue-black). (In alkaline solution.) 13. Xaphthol Hark B. OH SO Na SOsNa _ |_| S0Na^l^l'' = ''O^-K_> SOjNa E.P. 92US'; A.P. 345,901; D.P. 39,029; F.P. 170,342. 17'05 grams "amido-G salt" (acid potassium salt, mol. wt. = 341). 7'2 „ a-uaphthylamine. 15 „ "Rsalt." The amido-G salt (/J-naphthylamine-6 : 8-disulphonic acid) is dissolved in 250 c.c. of water, the solution cooled to 10°, and 15 c.c. of concentrated hydro- chloric acid added. The amido-compound is converted into the corresponding diazo-salt by adding a solution of 3'6 grams of sodium nitrite, and care must be taken that no excess of the latter is present. If a reaction is obtained with iodide-starch paper, a few drops of a solution of amido-G salt are added till no blue coloration is given by the diazo-solution. This is stirred mechanically. 23S SYNTHETIC HYESTUFFS. and a cold solution of 7 '2 grams of a-naphthylainine in 5 c.c. of concentrated hydrochloric acid and 100 c.c. of water run in. The mixture is stirred for several hours, warmed to 50°, and caustic soda solution added until an alkaline reaction is obtained. The latter is difficult to detect with tlie ordinary test-papers, and in this and other cases, where the colour or solubility of the substance to be tested prohibits the direct use of test-papers, the following method is adopted : — A cr^'stal of ammonium chloride is added to a few drops of the solution placed on a watch-glass, and the latter gently warmed with a very small flame ; a second watch-glass with a piece of moistened red litmus-paper adhering to its concave side is placed over the other one, and if the liquid is alkaline the litmus-paper will be turned blue. If this reaction is not obtained, more caustic soda must be added to the solution and the test repeated. Tiie alkaliue solution is now heated to boiling, the flame removed, and salt added until no more can lie dissolved. On cooling, most of the colouring matter is precipitated and is filtered. The paste is not dried, but immediatelj' diazotised and further combined. It is dissolved in 400 c.c. of cold water, and diazotised by adding 25 c.c. of concentrated liydrochloric acid and a solution of 3-6 grams of sodium nitrite, the whole being cooled with ice to about 10°. (Tiie solution is not tested with iodide-starch paper, as an excess of nitrite must be used. The mixture is stirred for several houi-s, and may, with advantage, be left standing overnight. The diazo-solution is now combined, whilst stirring, with a solution of 15 grams of " R salt " (mol. wt. = 348), dissolved in ISO c.c. of water, and IS grams of sodium carbonate (Na.COj). After an hour's further stirring the colouring matter is heated to SO', and salt added till the blue-black dye is precipitated and a dark red colour remains in solution (shown by spotting on filter-paper). This is now filtei-ed, dried, and ground. Properties. — Black powder, soluble in water with violet colour. Ityes wool bluish-black from an acid bath. Equations. —Free acids only are written. (1) so.;h SO,^ I I -■ ' NaN0., + 2HCl -^r (amido-ti salt). SO;fH'. CI N N + NaCl i •jH.,0 \ NK. (2) SO,H CI ^^J ^ <_> (a-naphthylamine) (3) soja so.;ff J.J ^-/ SO.H f NaNO.H 2HC1 >nh:, + HCl so,a -|N : N<( ^N i N + NaCl + 2HjO PREPARATION OF DYESTUFFS. 239 (4) + NaCl + NaHCO, so:h: (Naphthol black B). Note. — The formula of this dye is always written as the tetiasodium salt, but if the acid potasi^ium salt of amido-G salt is used (this being stable in the presence of hydrochloric acid), the dye should be, apparently, the potassium trisodinm salt. For the sake of simplicity, therefore, we have adopted the above method of expressing the reactions. 14. hodiphenyl hlai:l\ I<:.r. 20,278^'" ; A.P. 615,497 ; F.P. 270,1.51. OH CH. 1 OH I ■■ 0H<^ )>N : N<, >-N : N-^ ^ |^ = N< >NH„ NH2 15 grams ^)-amidoacetanilide. 24 ,, amidonaphthol sulphonic acid y. 10 ,, resorciuol. 10 „ «i-toluylenediamine. The amidoacetanilide is dissolved in water with the addition of 30 c.c. of con- centrated hydrochloric acid, the solution cooled with ice to 0-5°, and diazotised by adding 7'2 grams of sodium nitrite dissolved in water. This diazo-solution is poured into 24 grams of y acid dissolved in 25 grams of anhydrous sodium carbonate and 250 c.c. of water. 'J'he well-stirred mixture must be tested continu- ally during the addition, in order that an excess of alkali may be present. If the addition of the diazo-solution causes foaming, more sodium carbonate must be added. After stirring for a few hours the azo-colouring matter is heated to 80° and saturated with salt. On cooling, it is filtered. The reddish cake of colouring matter is transferred to a flask (or, better, an enamelled pan), mixed with a solution of 16 grams of caustic soda, and heated for about three hours until a nearly clear solution is obtained. The saponified product is allowed to cool, ice added till the temperature is 0°, and tetrazotised by the addition of 100 c.c. concentrated hydrochloric acid and 13-13'5 grams of sodium nitrite dissolved in water. The solution is continually tested with Congo paper during the diazotisation, and an excess of acid must be present. It is best to use a normal solution of sodium nitrite, and during its addition to test constantly with iodide-starch paper, so that the exact quantity necessary may be known. The above quantities of resorcinol and ;»-toluylenediamine are calculated for 13 grams of nitrite ; if a greater or less quantity is used, the amounts of the 240 SYNTHETIC DYFSTUFFS. two components will, of course, vary in proportion. When this operation is finished a clear red solution is obtained. This solution is now poured into a cold solution of 6.") grams of sodium carbonate (Na.iCOa), and then, immediately, the resorcinol. dissolved in a little water. The solution must show an alkaline reaction. After making this test the solution of m-toluylcnediaminc in water is added, and the colouring matter is complete (w-toluyleiio(iiatnine is used here instead of w-phenylenediamine, which is actually euiplo^'ed on the large scale ; the shade produced is practically the same). After stirring for an hour longer the dye is filtered and dried. Property's — Black powder, soluble in hot water with a violet-black colour. Dyes unmordanted cotton black. Equations. — — /CI (1) (C.JH.,,0)HN<^ \NH.,^NaNO.,^HCl -> ,C,II,0;HNv' (p-amidoacetauilide). (2) (CoHp)HN. NaCl-JHO (3) (CJa^OjHN (4) HjN. -r NaCl T NaHCO, CHjCOONa SOH ^ ;n ^ 3NaCl - 4H.,0 OH „, CH, 0H<^ \ + N i N<' \-N : N-,/ Y \ll I N + / >NHj + SOjHx /\ / I (resorcinol). NH., (w-toluylenediamine). 3Na.,CO, OH J oh/ Nn : N. CH3 OH J NH, (Isodiphenyl black). NH, + iNaCl - sNaHCO, PREPARATION OF DYESTUFFS. 24 1 15. Auramine 0. V N = N(CH.,),C1 E.P. 551 28^; A.P. 301,802s*; D.P. 29,060s-i; F.P. 160,99084. 25 grams tetramethyldiamidobenzophenone (Michler's ketone). 25 „ ammonium chloride. 25 „ anhydrous zinc chloride. The above quantities are well mixed together in a mortar and transferred to a porcelain dish or jar which has been heated in an oil-bath (temperature of bath, 200^). The mixture gradually melts together and becomes yellow. The mass is from time to time well stirred, and the temperature of the melt is maintained at 150-160' for four to five hours. The end of the reaction is reached when a test dissolves almost completely in hot water. After cooling, the hard mass is finely powdered and treated with cold water containing a little hydrochloric acid, in order to dissolve out the excess of ammonium chloride and zinc chloride. The residue is then extracted with hot water at 60-70°, filtered from any unchanged ketone, and salt added to the filtrate. The crystalline precipitate can be purified by recrystallisation from hot water, the temperature of which must not be over 70°. Properties. — Sulphur-yellow powder. Dyes silk and tannin-mordanted cotton greenish-vellow. Equations. — >N(CH,)., >N(CH,), CO(^ )^ + H.jNH: -^ Cfi-NH + H2O \ N(CH3)., N(CH3; (tetramethyldiamidobenzophenone) (Auramine (base)). (Michler's ketone). 'N(CH,), ^<^N(CH3)., C=NH + HCl -5. C^ NH2 ^<^ ^N(CH,), ^<^~^ = N(CH3).,C1 (Auramine (hydrochloride)). For an explanation of this formula, see p. 77. Note. — On boiling with water Auramine is slowly hydrolysed according to the equation C^NH + H.2O -> C^O + NH3 ^-<^~^N(CH,>, \^~^N(CH:,)., Care must be taken, therefore, when dyeing with this colouring matter that the temperature of the dye-bath does not rise above 60-70°, at which temperature the hydrolysis only takes place slowly. 16 >42 SYNTHETIC DYESTDFFS. 16. Malachite tjreen. o- '^/ \ = N(CHJ.C1 (hydrochloride). E.P. 4762"!'; (). Fischer, Ber., 1877, x. 1625. 0. :\Iiihlhiiuser, Dim/, pol. J., 1887, ccl.xiii. 249, 295 ; J.S.C.I., 1887, 433. 50 grams dimethylaiiiline. 20 ,, benzaldehjde. The dimethylaiiiline and benzaldeliyde are heated in a porcelain basin on the water-bath with 20 grains of zinc chloride, which has been previously fused and powdered. The mixture is stirred frequently and the heating continued for four hours. The mass is melted by heating with water and poured into a half- litre round flask. It is now treated with a current of steam, in order to drive over any unchanged dimethylaiiiline. Tlic leiico-base of the dye adheres to the sides of the flask and the zinc chloride solution is poured away. After washing the base with water it is dissolved in alcohol by heating on tlie water-bath, the solution filtered, and, after standing overnight, the base crystallizes out in colourless needles, which are filtered otl' and dried on filter-paper. By con- centrating tiie filtrate a second crop may be obtained. If the base separates out as an oily mass, the solution has been too concentrated, and it is redissolved with addition of more alcohol. iKn'i/iilion (if fill- li'uco-/iase. — For the oxidation of the leuco-base the quantities arc easily calculated from the following given for 10 grams : — This weight of the dry leuco-base is dissolved in dilute hydrochloric acid con- taining 27 grams HCl. This quantity must be exact. The clear solution is diluted with 800 c.c. of water in a large flask, 4 grams of acetic acid added (10 grams of 40 per cent, or 13 grams of 30 per cent), and the whole well cooled by adding ice. The leuco-base is now oxidised by adding (during five minutes) a thin paste containing 7 '5 grams of pure lead peroxide, the flask being well shaken. {Preparation of lead peroxide. — 50 grams of lead acetate are dissolved in 250 c.c. of hot water, and a filtered solution of 100 grams of bleacliing-powder in 1 i litres of water added. The whole is heated to boiling until the precipitate becomes dark brown. A small quantit}- is filtered hot and a few drops of bleaching-powder solution added and boiled ; if a dark brown precipitate is formed, more bleaching-powder solution is added to the main (juantity, and it is heated until a test gives no precipitate with tlie bleaching-powder solution. After settling, most of the clear liquid is poured ott" and the precipitate washed several times with water, the wash-waters each time being carefully decanted. The precipitate is now filtered at the pump and washed thoroughly with water. The lead peroxide is transferred, without drying, to a stoppered bottle. Before using the paste, the strength must be determined. See p. 267.) After adding the peroxide, the flask is shaken for five minutes, and then saturated with comiuon salt and allowed to stand. The lead chloride double salt crystallises out and is filtered ofl'. (The filtrate contains an inferior quality of green colouring matter, which may be separated by jirecipitating the lead witli sodium sulphate, filtering, and adding a little zinc chloride and salting out.) PREPARATION OF DYESTUFFS. 243 The double salt is dissolved in hot water, sodium siilphate added to precipitate the lead, and the lead sulphate filtered off. The filtrate is treated with ammonia solution, when the free base separates out as a pink pi'ecipitate, which is filtered and washed. From this eitlier the oxalate or the zinc chloride double salt is prepared — the former by dissolving the base in a hot solution of oxalic acid and cooling slowly ; the latter by dissolving the base in dilute hydrochloric acid, adding a solution of 8 grams of zinc chloride, and salting out. The dye is filtered and dried on a porous plate. Properties. — The zinc chloride double salt forms brass-yellow crystals ; the oxalate green metallic glistening plates, giving a bluish-green solution in water. Dyes silk, wool, jute, and leather a bluish-green ; cotton after having been mordanted with tannin and tartar emetic. Equations. — ,-. jhk:>(ch3, - x^y^.o^.) ;h:<(_^N(CH3), h \_/ (benzaldehyde). (2 mols.) (leuco-base of Malachite green), (dimethylaniline). (dye base (carbinol)). < >-C/ )=( + HCl -> / )>_c/ V/ + H,p (Ih\_>^(°^^>3 < > = N(CH,),C1 (Malachite green (hydrochloride)). For an explanation of these formulae, see p. 86. The formula of the zinc chloride double salt is SJ O^- CsHjNCCHs)., j + 2ZnClo + H.,0 \C6Hj = N(CH..).y 17. Magenta. CH, J 'C> NH.>C1 244 SYNTHETIC rtYESTUFFS. Haiissermann, Die Industrie der Tlieerfarh^toffe, 1881. Hannsen, Die Fabriimtion der Tiieerfarbstoffen und Hirer Rohmaterialien, 1889. Schultz, Chemie des Steinkohleritheers, 3rd ed., vol ii. p. 161. 20 grams aniline. ^ . -i- -, , , , ^. . ., ( Aniline oil for red, an • I i 1 J- ■ "4 per cent, ortlio > i ^/m oU „ commercial toluidine < o^ I sp. er. r004. I 36 ,, „ ;ja)-n ) *^ =" 67 ,, cone, liydrochloric acid. 55 ,, nitrobenzene. 3 „ iron powder. Fourteen grams of aniline and 54 grams of the toluidine are mixed together in a porcelain basin and the hydrochloric acid added. The mixture of hydrochlorides is heated till the temperature is 130°, when it is transferred to a round flask of onc-quarter-litre capacity, in which has been placed the rest of the aniline and toluidine together with the nitrobenzene. The mixture is heated in an oil-bath to 100°, when the iron, dissolved in 2 mols. of HCl (to form FeCl.,), is slowly added. Tiie flask is now connected with an air-condenser and the temperature raised gradually to 18U°, whicii is maintained for six to eight hours. The melt is flnislicd when a sample withdrawn on a glass rod solidities on cooling.' When this point is reached the contents of the flask arc distilled with steam, when a mixture of red oil and nitrobenzene passes over. The melt is now poured into 500 c.c. of boiling water, well stirred, and 12 c.c. concentrated hydrochloric acid added slowly. As soon as an acid reaction has been obtained, 25 gi-ams of salt are added, and the whole boiled for a few minutes. The aqueous solution which is poured ofV contains the hydrochloride of aniline and toluidine, which, as well as the previous distillates, is, on the large scale, used again in the manufacture (see also Sa/ranine). The residue is allowed to cool, and solidifies to a green, brittle mass, which is weighed. This is tlicn broken up and extracted with li litres of boiling water contain- ing 12 c.c. of HCl, which dissolves the Magenta. After filtering, the solution is allowed to cool to 60°, when a little violet colouring matter separates out, which is filtered ofl'. Salt is now added to the Magenta solution, the weight being the same as the weight of the crude melt. After standing some time the crude Magenta separates out, is filtered oft', and recrystallised from water containing a little hydrochloric acid. The filtrates from the purification of Magenta are, on the large scale, worked up, and the colouring matters obtained from them sold under the names of Phosphine, Maroon, Cerise, etc. Propi'rties. — The hydrochloride forms glistening crystals with a greenish reflection, dissolving in water to a red solution. Dyes silk and wool bluish-red direct : cotton, after having been mordanted with tannin and tartar emetic. Equations. — (1) CH/'~\nH., + O., -> //~^NH.. -I- HjO \_/ - - HC/^— ^ I (/'-toluidine). O (;)-amidobenzaldehyde). ' Begin to test after three and a lialf lioui-s — three to four hours may be sufficient. (2) (3) (4) PREPAKATION OF DYESTUFFS 245 CH, ;(o-toluidine). (aniline). \ CH, J ■NH., NHl, H V'^NH., CH.5 C— /^NH., + HCl I — CH3 C^^_^NH, + H.,0 i X">NH, (leuco-base of iMageuta). CH3 (carbinol base). CH, I + H,0 ^/ '> = NH.,C1 (homorosaniline chloride (Magenta)). At the same time there is also formed >NH, > = NH,C1 (;««•«- rosaniline chloride), owing to the interaction of 2 mols. of aniline in equation (2) instead of 1 mol. of aniline and 1 of o-toluidine. 18. Methyl violet B. ^v >NHCH, / <0'N(CH3)„ =N(CH3)201 Miihlhaiiser, Dingl. pol. J., 1887, cclxiv. 37; J.S.C.I., 1887, 434. Harmsen, Die Fahrikation, etc. 875 grams sodium chloride. 50 ,, copper sulphate. 40 ,, phenol. 100 ,, dimethylaniline. 246 SYNTHETIC DYESTUFFS. The salt and copper sulphate (finely powdered) are well mixed togother in a mortar, and a solution of 40 grams of j)henol in 10 c.c. of water added, and the whole stirred well. The dimethylaniline is now added, and the mixture transferred to a round flask and heated on the water-bath for eight hours at 55°. The product is poured out into a porcelain basin and allowed to cool. In order to free it from phenol and salt, it is broken up and added gradually to 3 litres of boiling water, to which has been added milk of lime prepared from 40 grams of quicklime and 200 c.c. of water. After heating till no more lumps are present, the mixture is allowed to settle, and the clear solution of salt and calcium phenate decanted. The residue of copper oxide, methyl violet, and calcium sulphate is washed again by decantation and finally filtered. In order to get rid of the cojsper oxide the precipitate is boiled with dilute sulphuric acid, and sodium sulphate (free from chloride) added to precipitate the dye, which is filtered aud washed. The precipitated violet is subsequently dissolved in water and reprecipitated with salt. Properties. — Methyl violet is a glistening greenish powder, dissolving in water with a violet colour. Dyes silk and wool violet direct : cotton, after mordanting with tannin and tartar emetic. Equation!'. — (^) / NncCHj)., + O -> CH.,0 + / \nH(CH.,) m (3) H-C H<^ NnH(CH3) ■h<(_^N(CH3)., H<^_)>N(CH3)2 /\_/ iH\ NH(CH,) •N(CH3), 'N(CHa).. + HCl -> :0 -^ C^/^NCCHj).. + 2H.,0 0^'^<(^N(CH3)„ (carbhiol base). ^' — "\ ^N(CH,,)., + H.,0 / N = N(CH,).,C1 (Methyl violet B (hydrochloride)). 19. Aniline blue (spirit soluble) or Opal blue. ^/"^ = NHC,H,C1 ,1. dc Mollins, De la fabrication ties Bleus d'aniline et de dipihenylamine, 1885. 25 grams rosaniline base (prepared from Magenta).^ 250 ,, aniline. 3 ,, benzoic acid. By bulling willi caustic suJa solution. PREPARATION OF DYEST0FF8. =47 The above quantities are placed in a flask provided with a thermometer and a Ions bent tube to collect a small amount of aniline, ammonia, and water which distils over during the operation. The flask is heated slowly on a sand-bath to 180°, and maintained at this temperature until a few drops dissolved in alcohol and a little glacial acetic acid and poured on filter-paper show a pure b ue colour by daylight, which is only tinged slightly red m gaslight lliis operation requires about three hours. The hot melt is then poured into a beaker allowed to cool a little, and 215 grams of hydrochloric acic^ 28 per cent, (or 194 grams of pure concentrated acid, 31 per cent.), added. The Opal blue is thus precipitated, whilst an impure blue remains dissolved in the mixture of aniline and aniline hydrochloride (formed by the partial neutralisation of the aniline). The mixture is filtered hot at the pump, and the Opal blue washed with boiling water to which a few drops of hydrochloric acid have been added. ihe colouring matter is dried on the water-bath. It is thus obtained in the form of a greenish or reddish brown crystalline powder. Yield about ^'^ThT'filtrate containing the impure blue is acidified with hydrochloric acid, whereby the colour is precipitated, and is filtered, washed as above, and dried. Yield about 15 grams of impure blue (dyeing duller and redder shades than ^^%°th the shade and the yield depend largely on the length of time during which the heating is carried on. Care must be taken not to allow the tem- perature to rise above 180°. , , , -r^ -n a „„i Properties.— Insolnhle in water, but soluble in alcohol. Dyes silk and wool Kreenish-blue. Equations. — .<^^)>NH., H„NC„H„ /"(ly^ o^<^Nnh:, + h:.nc,,h-. -> 9^<^nhc,h, + 3NH, SNHCsH, (1) C^^^^NHL, + H.,NC,iH, " ^ OH \( ys-B., H.,NC,H„ 6h\^^^NHC„H, (rosaniliue base). (Rosaniline blue) (base). (2) C^<">NHC«H, + HCl -^ C^<_>NHC,H, + H,0 OH\<^='^NHC,H, \<;^ = NHC,H,.C1 (Aniline blue (spirit sol.) (See p. 90.) hydrochloride). Owing to Magenta being a mixture of para- and /ioj;JO-rosaniline, there will also be formed in this reaction a blue of the formula CHa I \<^^ = NHCeH5 248 SYNTHKTIC DYESTUFKS. 20. AUcali hhie. HO— C^ / ^NHC.Hj 25 grams Aniline blue (spirit soluble). 250 „ cone, sulphuric acid (140 c.c). The sulphuric acid is placed in a 500-c.c. flask, and the Aniline blue, which is obtained from the melt in the form of a fine crj-stalline powder, is slowly added, keeping the temperature below 35°. The experiment should be conducted in the draught cupboard, as hydrochloric acid is evolved. When all the blue is dissolved, the temperature is maintained at 35-40° until a few drops diluted with water and filtered yield a residue which dissolves in a weak boiling solution of caustic soda. The sulphonation mixture is then poured into about 2 litres of cold water, filtered at the pump, and the precipitate washed with water luitil free from acid. The moist free acid thus ol)tained is transferred to a porcelain basin, made into a thin paste with hot water, and converted into the sodium salt by the cautions addition of caustic soda solution, the whole being heated to boiling. If the correct amount of caustic soda has been added, a sample will dissolve completely, in hot water, with a blue colour. Should, however, an excess of alkali be present, the colour will be brown, and in this case a weak solution of suljihuric acid is stirred slowly into the hot mixture until the right point is reached. The solution is then evaporated nearly to dryness on the water-bath, and finally dried at 50°. Propi'.rtieit. — Blue or bronzy powder, sparingly' soluble in cold, easily in hot water with a blue colour. Dyes wool blue from a boiling bath made alkaline with borax, the colour being subsequently developed by passing through weak sulphuric acid. E'juafions. — (1) /"Nnhch, / \nh.c„h.so.ii C— <^ ~^NHC,iH,-, + H.SOj -> C— < \NHC„H, + HCl Wn /~\ = NHC,.H,C1 "■" Y ^NHCfiHis (Uosaniline blue). (.\lkali blue) (free acid). (2) ^<(^ ^NH.C5HjS0:,H ,/^NH.C,;H,SO,,Na C^ < >NHC„H, + NaOH -> C^^< NNHC,H;. + H.,0 --'^ / \nHC„H, h NaOH -> C^ NHC„H., °^ \_)NHC„H. (Alkali blue). PREPARATION OF DYESTUFFS. 249 This product will also be mixed with the corresponding homorosaniline derivative _l / NNH-CeH^SOsNa OH \/~\nhC„H. See previous preparation. 21. Soluble blue. ,/~\NHC,iN4S0;,Na HO-C— / NNHCjHjSOjNa ■NHCeHjSO^Na 25 grams Aniline blue (spirit soluble). 100 „ cone, sulphuric acid (55"5 c.c). The blue is gradually added to the acid contained in a flask, and the whole heated on a sand-bath up to 90-100°, until a sample poured into a little water and filtered is soluble in warm water. The sulphonation mi.xture is now poured into about 500 c.c. of cold water and filtered at the jjump. ' The precipitated colouring matter is washed only with a little water, as it is soluble in pure water. It is transferred to a basin, a little water added, and the mixture heated to nearly boiling, then neutralised with caustic soda solution until the whole is soluble with a blue colour. If the mixture turns brown there is too much alkali present, and this must be neutralised by the cautious addition of weak sulphuric acid. It is evaporated to dryness on the water-bath and ground. Yield about 30 grams. Properties. — Blue powder, soluble in water. Dyes silk and mordanted cotton, blue. Equations. — -^ yNHCeHj / NNH.CgHjSOjH C^/ NnHCjHs + 3H2SO4 -^ C— /^NH.C,iHjS03H -1- 211,0 -l-HCl ^/~\ = NHCsHjCl OH \/~Xnh. CjH^SOjH (Eosaniline blue). (Soluble blue) (free acid). ,<(^^NH.C6H,S0,H ^/^NnHCsH^SOjNa C— /~~\NH.aH,SO,H + SNaOH -> C— /~^\NHC„H,SO,Na -1- 3H.,0 |\ \-/ |\ \=/ OH\/~XifH.C6H,S03H 0H\/ NNHCeH.SO^Na (Soluble blue). 250 SYNTHI'mC DYKSTUFFS. Tills blue will also be accoiii])aiiied by the corresponding liomorosanilinc derivative CH, / NNH.CiH^SOjNa C— < \NH.C„H.SO,Na <1h '/ ^NH.C,,H^SO.,Na Fluorescein and Eosine. Muhlluiuscr, Dingl. pol. J., 1887, cclxiii. 49; J.S.C.I., 1887, 283; Dinijl.poL J., 1892, cclxxxiv. 21, 46; J.S.C.I., 1892, 675. Beruthsen, Che7n. Zeit, 1892, xvi. 1956; J.S.C.I., 1893, 513. 22. Fluorescein O H0(^ ^/^,/NoH NaO, c .0 iCO / \C001fa (free acid). (sodium salt). 15 grams phthalic anhydride 22 „ resorcinol. 7 „ zinc chloride. The materials are ground together in a mortar and heated in an oil-bath to 180°. For this purpose a nickel crucible may be used.' As soon as the tem- perature has readied 180°, 7 grams of powiicred fused zinc chloride are added gradually during ten minutes, the melt being stirred with a glass rod. After the zinc chloride has been added the temperature is raised to 210°, and kept at this point till the mass becomes solid (t)iie to two hours). The cold melt is broken out of the crucible or jar with a knife or chisel, powdered, and dissolved in dilute caustic soda. After filtering, hydrochloric acid is added, which precipitates the fluorescein ; this is filtered, washed, and dried. The crude substance is treated with boiling alcohol, and the residue, after filtering, dried. Yield about 32 grams. 23. Fosiur. Br O Br q C I^COONa \y (sodium salt). 15 grams fluorescein. 33 ,, bromine (11 c.c). 60 „ alcohol. An "extract of liccl" jar is ulso very convenient. PREPARATION OF DYESTUFFS. 25' The fluorescein is placed in a flask, 60 grams of alcohol added, and the bromine dropped in slowly from a small separating funnel. When half the bromine has been added, the dibromide which is formed is in solution ; but on further addition of bromine, the tetrabromide separates out. After standing for two hours the precipitate is filtered, washed first with alcohol, then with water, and converted into the sodium salt by mixing it with a little hot water, carefully neutralising with caustic soda (avoiding an excess of this reagent), and evapora- ting to dryness on the water-bath. Properties. — Eosine forms bluish-red crystals or a brownish-red powder, dissolving in water with a bluish-red colour. Dyes wool and silk yellowish-red. Rjuations.— (resorcinol). (resorcinol), HO^,OH 0]^/\,0H V^H^H o C / Aco (phthalic anhydride). + Hl.O C 7O (Fluorescein) (free acid). Br O Br HO|/\|/\,-^,OH + 4Br., -5. (Eosine) (free acid). J, 2NaOH Br O Br f. Br\/\y-\^Br + 2H„0 C /^.COONa \/ (Eosine) (sodium salt). For a further explanation of these formulae, see p. 107. 2152 SYNTHKTir DYRSTUFFS. 24. Jiliodamhte B. C |-^^|COOH \y E.P. 15,374"; A.P. 377,349 and 377,350«8; D.P. 44,002"; F.P. 186,697". 5 grams dietliyl-»ie^aamidopiieiiol. 9 ,, jihtlialic anhydride. 6 ,, anhydrous ziuc chloride. The two first are well mixed together in a mortar and the mixture transferred to a nickel crucible,' which is heated in an oilbath. The temperature is raised slowly to 100°, the flame withdrawn, and the powdered zinc chloride added, the whole being well stirred. The temperature is then raised gradually to 180°, water vapour is given oft', and the reaction is finished when a sample withdrawn by a glass rod completely solidifies on cooling. This takes about four to five hours. The solid product, when cold, is finely powdered and extracted with boiling alcohol on a reflux condenser. The alcoholic solution is filtered and allowed to stand. The colour-base crystallises out and is filtered. The base is dissolved in a small iiuantity of water and dilute hydrochloric acid, and the solution allowed to cool, when the hydrochloride separates out, and is filtered, and dried on a porous plate. Properties. — Green crystals, easily soluble in water. Dyes wool and silk bluish-red, tannin-mordanted cotton violet-red. Equatioiis. — (Diethyl-»i-amidopiicnol). (C.B,).,N,/\.OH HO/\N(C.a,), (C.H,),N,/^,OH HO|/^,N(C..JHJ, o c' — >o vco r lOo (phthalic anhydride). (the phthaleiti). I - H.,0 O (Rhodaniine) (base). ' Or an "extract of meat " jar. PREPARATION OF DYRSTUFFS. 25; ,N(C5H5)2C1 o o H- HCl \/Y^ (Ehodamine B) (hydrochloride). For au explanation of these forniulpe, see p. 107. 25. Benzoflavine. N CH, S.j!t.^Y "^1^ iNHL.HCl E,P. 96US8; A.P. 382,832; D.P. ■43,7143?; 43,7208". /. Preparation of tetramidojphemjhlitoljilmetliane. — 20 grams metatoluylenediamine sulphate.' 5"5 ,, benzaldehyde. 40 ,, alcohol, .50 per cent. These are mixed together in a round flask of 12.5-c.c. capacity, fitted with a retiux condenser, and gently boiled on the water-bath. When the smell of benzaldehj'de is no longer present, the alcohol is distilled ofl^, and water added to the residue ; the sulphate of the above base is filtered and dried. //. Preparation of dihydrodiamidodimetlujljihenylacridine. — 20 grams of the crude sulphate prepared as above are heated with 36 grams of concen- trated hydrochloric acid and 36 c.c. of water in a sealed tube (larger quantities may be heated in an autoclave) for three hours to 130-140°. After cooling, the tube is opened and the product used directly, without purification ///. Preparation of the colouring matter. — 20 grams of the hydrochloride of dihydrodiamidodiraethylphenylacridine are dissolved in water containing hydro- chloric acid, the solution cooled to 0°, and 20 grams of zinc chloride, dissolved in a little water, added. The solution is stirred and 70 grams of an ice-cold 30 per cent, solution of ferric chloride (FeClj.GHoO) added. The colouring matter separates out as a voluminous orange-yellow precipitate, which is filtered, pressed on a porous plate, and dried at 50-60°. Properties. — Brownish orange-yellow powder. Dyes silk, wool, and mordanted cotton yellow. ' This is obtained by neutralising a strong solution of metatoluylenediamine in liot water with dilute sulphuric acid, when the sulphate crystallises out on cooling. 2 54 SYNTHETIC DYRSTUFFS. Equations. — (m-toluylenediamine (2 inols.)). NH/^.NH., H.,n/\wh., O "ii CH (benzaldeliyde). Yh (tetramidophenylditolylmetliane). CH (dihydrodiainidodimethyliihciiyliicridine). \,/ N HoN,--^/ \^~ ,NH., C /\ I I V (Benzoflavine). + H..0 26. Alizarine ijellmv A. 0H[1] C,;H,CO.C,,H, OH [J] ■^OH [3] E.P. 8373S'\ 9428S!\ 10,095»»; A.P. 198,281«'^ D.P. 49,149«', 50,4508'', 50,451«-', 54,661'"' ; F.P. 198,281S''. 12 grams pyrogallic acid. 12 „ benzoic acid. 36 ,, anhydrous zinc ciiloridc. The above quantities arc mixed togetlier and put in a 200-c.e. crucible or jar, which is heated in an oil-batli. Tiie temperature is gradually raised to 145°, and the reaction is finished when there is no more foaming and the brown colour does not increase. The cold product is powdered and boiled with water and a little animal charcoal and filtered ; the needle-shaped crystals of the dyestuff separate out on cooling, which are filtered and dried. Properties. — (Treyish-ycUow crystals. Dyes cotton, mordanted with alumina and lime, a fast golden yellow. It is used for printing. PREPARATION OF DYESTUFFS. 255 Equation. — CsHjCO OH 4 H C^H2(0H),[1 : 2 : 3] (benzoic aoid). (pyrogallic acid). CcH;.CO.C6H2(OH),[l : 2 : 3] + H2O (Alizarine yellow A). Alizarine. E.P. 193663; A.P. 153,536. Perkin, E.P. 1948«8, J.S.C.I., 1883, 213. 50 grams sodium anthraquinone sulphonate. 150 ,, sodium hydrate. 9 ,, potassium chlorate. The caustic soda is dissolved in 150 c.c. of water in an autoclave, and the sodium anthraquinone sulphonate stirred in. The potassium chlorate is dissolved in 50 c.c. of hot water and thoroughly mixed with the mass. The lid of the autoclave is then fixed on and the whole heated for twenty hours to 170°. After cooling, the melt is extracted with boiling water several times, and the solution acidified with hydrochloric acid. The alizarine which separates out is filtered at the pump, washed with water, pressed on a porous plate, and dried at 120°. Properties. — Yellow powder, slightly soluble in boiling water ; can be sublimed to long red needles. Dyes cotton, mordanted with alumina, scarlet-red ; with tin, bluish-red; with iron, violet; with chromium, brown. Equation. — (1) NaOiH + NaOH ; + O Na OH ONa ^ I I I I CO (sodium salt of Alizarine) + Na SO + 2H,0 CO ONa ,ONa CO OH + 2HC1 256 SYNTHETIC DYF.STUFFS. 28. iTuluphenol. (CH,),N-<^ \>-N = <^ = o E.r. 137381, 524981; a.P. 261,518; D.P. 15,915'*', 18,9038', 19,231*1, 20,850«i. J.S.C.I., 1882, i. 255. 10 grams nitrosodimethylaniline hydrochloride. 10 ,, zinc dust (sieved). 12 „ a-naphthol. 3'3 „ caustic soda. 10 „ potassium bicliromate. The nitroso-compound is dissolved in 1 litre of water and reduced by adding the zinc dust and wanning the solution to 45-50°. The mixture becomes colour- less, and is filtered from the zinc and zinc o.vide. The solution of amidodimethylaniline is mixed with the naphthol solution prepared by dissolving the naphthol in 3'3 grams of caustic soda and a little water, and to this is added the solution of bichromate in :i00 c.c. of water. The mixture is well stirred mectiunioally, and ordinary acetic acid, 30 to 40 per cent., is slowly added till an acid reaction is obtained. The dye is formed and is precipitated. This is filtered, washed, and dried. Properties. — Indophenol is a dark brown powder, insoluble in water. Use. — Indophenol is converted into the leucocompound by reduction with stannous chloride or acetate, wliich is then used for printing and dyeing in tlie same way as Indigo. Equations. — /\/NO ^. Ntt, (^) 11+ 2Zn + 2lip -> 11+ Zn;Cl)OH rZn(OH)., C1H.(CK,).n/^/ (Ckj.jj/'^ (nitrosodimethylaniline) (dimethyly)-phcnylene- (hydrocliloride). diamine). (a-napiitliol). (Indophenol). On reduction Indophenol is converted into Indophenol white N /-\ NH /-\ (Indophenol white), in which condition it is soluble in alkali, and then possesses affinity for tlie fibres upon which it can be reconverted into the blue on oxidation in the air. PREPARATION OF DYESTUFFS. 257 29. Meldola's blue {Naphfhol blue) C1(CH,),N- MeWola, Ber., 1879, xii. 2065 ; J.C.S., 1881, xxxix. 37. Witt, Ber., 1890, xxiii. 22-17. jNIeldola, Private comviunicafion. 21 grams yS-naphthol. 53 ,, uitrosodimethylaniline hydrochloride. The above quantities are dissolved in alcohol and heated on the water-bath in a round flask, fitted witli a reflux condenser, for a day. The colouring matter is formed, and is separated by adding a solution of zinc chloride until no further precipitate is obtained. The zinc chloride double salt is filtered and dried on a porous plate. Yield 30 grams. Properties. — Dark violet powder, soluble in water with bluish-violet colour. Dyes cotton, mordanted with tannin and tartar emetic, indigo blue. Equation. — HO (;8-naphthol). 3 I I ClH(CH;,)oN/ ' (nitrosodimethylaniline) (hydrochloride). (Meldola's blue). ClH{CH.,).Nl \/ The formula of this substance, as a derivative of o-quinone containing tetravalent oxygen, wo\ild be 30. Gallocrjanine. N(CH3: '7 258 SYNTHETIC DYESTUFFS. E.P. 4899"; A.P. 253,721 and 257,498; D.P. 19,580". 10 grams gallic acid. 17 ,, nitro.sodimetlijlauiline hydrochloride. 200 c.c. alcohol, 95 per cent. The above quantities are mixed toj^'cther in a 500-c.c. round flask fitted with a reflu.x condenser, and heated on the boiling water-bath. The course of the reaction is observed by spottini; a drop on filter-paper and observing the colour. Wlien this is dark violet-blue, and does not change on further heating the flask, tiie reaction is finished. There must also be no yellow rim round the drop of colour on the filter-paper. Tlie alcohol is distilled off on the water-bath and the residue evaporated to dryness. This is boiled with 200 c.c. of water, filtered, and dried on a porous plate, and finally at 40-.50°. Propi'iiies. — I'ronze powder, insoluble in water. Dyes chrome-mordanted wool bluish-violet, and is used in printing upon chrome-mordanted wool and cotton. Eqiudidns. — ■ COOH \ ho' Iqh ) "*" ^ ( '.Jn(CH,,)JHCi) OH / (gallic acid). COOH N . X\/\^ \ H,N./\ +3H,0 OH. ^1 J, J ' I JN(CH3).aCl 6h O ^ N(CH,),Cl/ \/ (hydrochloride). ,!, -HCl O I CO N VY^Vch,, ((lallocyaninc). The formula of this substance would be represented by N CO O (OH...).y^l^;^>H d OH I on the assumption that the o.xazinc salts are derivatives of o-quinone containing tetravalent oxygen (see p. 125). 3 1 . Metlii/leiif hlue. (CH3),N' N I I I ^/ \/ ^ii(CH3),,Cl PREPARATION OF DYKSTUFFS. 259 E.P. 438«; D.P. 38,573s'', 39,757*'^; A.P. 362,592, 366,639, 366,640, 384,480; F.P. 173,137, 181,827. 24 grams dimethylaniline. 65 ,, cone, hydrochloric acid. 7'1 „ sodium nitrite. 20 „ zinc dust. 50 ,, sodium thiosulphate. 25 ,, potassium bichromate. 53 ,, sulphuric acid. 8 „ neutral sodium chromate. Twelve grams of dimethylaniline are dissolved in a mixture of 40 c.c. of water and 65 grams of concentrated hydrochloric acid, and the solution cooled with ice to 12-15". This is stirred mechanically, and a solution of 7'1 grams of sodium nitrite run in slowly (delivery tube underneath the surface of the liquid), taking care that the temperature does not rise above 15°. The nitroso-compound is reduced by adding about 20 grams of zinc dust carefully', and the reduction is complete when the solution is of a clear red colour. The amount of zinc added must be sufficient to neutralise the hj'drochloric acid, so that Congo paper is no longer turned blue. The solution is now diluted with water to 600 c.c, and a solution of 12 grams of dimethylaniline in the exact quantity of hydrochloric acid necessary to form the hydrochloride (about 10 c.c.) added, and then a solution of 50 grams of sodium thiosulphate in a little water. The mixture is oxidised by adding a concentrated solution of 25 grams of potassium bichromate and boiling for two hours. Fifty-three grams of sulphuric acid first diluted with 100 c.c. of water are now added, and the solution boiled to expel SOj. The leuco-methylene blue is oxidised by adding 8 grams of neutral sodium chromate dissolved in a bttle water, and the resulting dye is precipitated by adding salt. The base is filtered, dissolved in a little boiling water to which a little hydrochloric acid has been added, and the hydrochloride precipitated by common salt, filtered, and dried on a porous plate. Properties. — Dark green or red-brown bronzy powder, easily soluble in water, forming a blue solution. Dyes tannin-mordanted cotton blue. Equatiuns. — J + H5S.,0, -). O -> II + H.,0 (CH3).,N/ ^ (CH3).,IJ-/^^-S.S0.,H (dimethyl-^)-phenyleuediamine). (thiosulphonic acid of dimethyl- ^5-phenylenediamine). I J +11 + O., (dimethylaniline). N I I '^l L II"" SO3 1 (tliiusulphonic acid of an indamine). 26o SYN'TITETir PYKSTT'FFS. (3) N N \/\s\/\.N(CH,)., •*'- \/Y\/^N(CH3>,Cl SO3 I (l^retliylene blue). This Bubstunce, formulated as an ((-quinoiie dLiivativo containing tetravalent oxygen, would be N 6 I ci 3i'. Safranbie. 'Na, C„H, CI CjH, Walter, Auit der Praxis toluidine sulphonic acid, which is always present, and the filtrate contains the primuline. This is saturated with salt, when the primuline separates out, and is filtered and dried. Pnijie/iieg. — Yellow powder, easily soluble in water. Dyes unmordanted cotton primrose yellow from an alkaline or neutral bath ; this is usually diazotised on the fibre and developed with y8-naphthol, when a fast red is obtained. Equations. — (See p. 153.) 36. Indigo. Sandmeyer, Zeit. Farh. Textil. Chem., 1903, 132; J.C.S., 1903, Ixxxiv. 486. /. Preparation of hydrocyanocarhodvphenylimide. — 200 grams thiocarbanilide. 70 ,, potassium cyanide (96 to 98 per cent.). 300 ,, basic lead carbonate (white lead). 500 „ alcohol. 264 SYNTHETIC DYESTUFFS. The potassium cyanide is dissolved in 200 c.c. of water, and the solution mixed witii tlie thioearbaiiilidc, white lead, and alcohol. The whole is slowly warmed, with frequent shaking, to 50-60° on the water-bath. The reaction is soon Hnished, and the end is reached when a tiltered test, boiled with a little white lead, does not blacken the latter. After cooling, water is added and the precipitate filtered, washed, and dried. The dry residue is extracted with alcohol, the alcoholic solution filtered from the lead sulphide and concentrated. On cooling, pale yellow prisms of the hydro- cyanocarbodipheuylinjide crystallise out and are tiltered and dried. //. Preparatim of thiooj-aiitioUphenylamidine. — 200 grams of the finely powdered liydrocyanocarbodiphenyliuude are mixed with 500 grams of a yellow ammonium sulphide solution (this is made by passing 35 grams of sulphuretted hydrogen into 4i0 grams of 21 to 22 per cent, ammonia, and dissolving 25 grams of powdered sulphur in the colourless solution) in a flask. The flask is closed and allowed to stand at 25-35° till a filtered test, after being well washed, dis- solves completely in dilute hydrochloric acid. This takes about two days. The thioamidine, which is a lemon-j'ellow powder, is filtered, washed, and dried. It forms gold-yellow crystals when recrystallised from alcohol, melting at 161-162°. III. Preparation of a-isatinanili'h'. — 200 grams of the dried thiooxamicdi- phenylamidine are added to 800 grams of concentrated sulpiiuric acid (444 c.c.) which liave been previously warmed to 90°. The mixture is well stirred and the temperature not allowed to rise over 95°. Sulphur dioxide is evolved and the substance goes into solution ; the sulphuric acid becomes coloured first dark brown-violet, and finally yellowish red. Wlien all is added the temi>erature is raised to 105-110°, till no more sulphur dioxide is evolved. After cooling, the mixture is poured into a solu- tion of sodium carbonate sufficient to neutralise the acid containing lumps of ice. The precipitated a-isatinanilide is filtered, pressed on a porous plate, and dried at a low temperature. It forms violet-black needles melting at 126° when recrystallised from benzene or carbon bisulphide, and orange-red plates from alcohol. IV. Conversion of a-iga(inanili'le into Indigo. — 200 grams of a-isatinanilide are dissolved in 600 grams of alcohol and the solution warmed. To this is added 400 grams of a freshly prepared solution of ammonium sulphide con- taining 10 per cent. H.,S. Indigo separates out in copper-glistening crystals: and, after treating the solution to boiling for a short time, these are tiltered off, washed first with alcohol, then with water, and, after drying, extracted with carbon bisulphide to remove the last traces of sulphur. Properties. — Hark blue powder. (For analysis, see ji. 305.) Equ'itions. — (Thiocarbanilide). (1) l^r^^ . -. CY^ + KHS '^ C-NHiC,Hj ^ C = NCeH5 II ■■ ■ : I S CN + k;cn (potassium cyanide). (hydrocyanocarbodiphenylimide). PREPARATION OF DYESTUFFS. 265 ^y C = NaH, \/ C = NC,3H5 I I CN CSNHo (thiooxamicdiphenylamidiiie). (3) 2 I V^^-? = ^°^» + 2H.50, / ,-NH-C = NC,H, -> 2 I -■- (NHjlSOj^ SO., hH.,0 + S I i CO (a-isatinanilide). NC,;H5 NCbH-, / VNH-C C— NH-/ I (4) I I + I + -iK, i-^,— NH^C = C— NH— ,/^^, II + 2C0H5NH0 no r.o I I (Indigo). (aniline). 37. Siiljilncr hiack T (constitution unknown). E.P. 11511800; A.P. 655,659; D.P. 127,835; F.P. 299,721. 60 grams a-dinitrophenol. 90 ,, sulphur (flour). 250 „ sodium sulphide (cryst.). The sodium sulphide is dissolved in 300 c.c. of water in a round flask, the sulphur mixed with the solution, and then the dinitrophenol added gradually. The flask is attached to a reflux condenser, and heated to boiling on a sand- bath for about fifteen hours. The liquid is now transferred to a filter-flask fitted with a cork and a straight glass tube reaching to the bottom, and the side-tube connected with the vacuum pump. In this way a stream of air is led through the liquid and the dye is precipitated. When a drop on filter-paper shows a colourless rim, the mixture is filtered at the pump, dried, and powdered. Yield about 120 grams. Pro2Kriies. — Black powder, soluble in dilute solution of sodium sulphide with black colour; insoluble in alcohol. Dissolves in concentrated sulphuric acid on warming with dirty green-blue colour. Dyes unmordanted cotton in a bath containing sodium sulphide direct black. Equation. — Unknown (see p. 167). PART III -ANALYTICAL. CHAPTKlt XXX. COMPOUNDS USED IN CONNECTION WITH THE DYESTUFFS. I. INORGANIC PRODUCTS. Fuming Sulphuric Aciil. Fuming sulpliuric acid is usually looked upon for analytical purposes as a mixture of sulphur trioxide (SO3) and sulphuric acid (H.,SOj). It always contain.'^, however, small (|nautities of sulphur dioxide (SO,,), and the amount of this i.s specially determined. The fuming acid is melted, if necessary, and a sample transferred to a narrow-mouthed stoppered bottle. In order to weigh out a portion for analysis, the followinj; method is adopted : — An ordinary test-tube, about J of an inch wide, is drawn out aboiit \\ inches from the bottom to a tine capillary tube about IJ-li inches long, which is weighed, and then the enil of the capillary tube dipped into the acid. Tiie bulb is now warmed by a flame expelling some of the air, so that, on cooling, the acid rises into it. The weight of the acid should be about 8-10 grams. The capillary end is quickly withdrawn, sealed in the flame, the tube cleaned and weighed. It is now dropped into a litre flask containing 200-300 c.c. of water, the stopper replaced, and the bulb broken by shaking. The flask is cooled for a minute under the tap, and after a short time the white fumes are entirch' absorbed. The solution is poured off from the broken glass, made up to 1 litre, and 250 c.c. titrated with normal caustic soda solution, using methyl orange as indicator. It is necessary to remember here that 1 c.c. normal caustic soda solution (0'040 gram NaOH) neutralises .'. molecule SO3 (0'040 gram SO„) and a whole molecule of SOo (0-004 gram" SO.,). A second quantity of 250 c.c. is now titrated with one-tenth-normal iodine solution (a few drops of starch solution are added, and the iodine run in till a faint blue colour is obtained). ( hie c.c. one-tenth-normal iodine solution corresponds to 0'0032 gram SO., ; thus for each c.c. of iodine used, 0'05 c.c. must l)e subtracted from the number of c.c. of normal caustic soda used in the first titration, in order to arrive at the correct amount of SO3 present. An example will show how the calculation is made: — 97104 grams fuming acid dissolved in watfr up to 1 litre, 250 c.c. taken for each analysis. For the SO,, determination r21 c.c. of one-tenth-normal iodine were used, corresponding to 1-21 x 00032 = 0-003872 gram SO.^ = 0-16 per cent. SO„. Further, by titration with methyl orange 52-38 c.c. of normal caustic soda INORGANIC PRODUCTS. 267 were used, from which 0'06 (correspondins to r21 c.c. of the iodine solution) are subtracted, so that we have 52-32 c.c. = 2-0928 grams 803 = 86-2 per cent. The fuming acid thus contains 85-2 SO3 0-16 SO„ 13-64 H,,0 13-64 water combine with 13-61x4-44 = 60-56 SO3, so that the acid contains 86-2 - 60-56 = 25-64 per cent. SO3. The complete analysis is therefore H.,SO, .... 74-2 SO3 . . . . 25-64 SO2 . . . -16 100-00 Zinc Du»1. ^Method of Knecht and Rawson. — The zinc dust is treated with excess of potassium bicliromate solution in presence of sulphuric acid, whereby a portion of the Ijichromate is reduced. 3Zii + 7H.3S04 + K,Cr.,0, = Cr2(S0,),, + .3ZnS0j + K^O^ + 7H„0 All excess of ferrous ammonium sulphate is now added, a jiart of which is oxidised by the bichromate remaining. 6(FeSOj.(lIH4)2S04.6H.,0) + K,Cr.,0, + SUSOj = 3Fe._,(S0j);, + e(NHj).JS04 + 2KHSO4 + CroCSOj), + 43H.,0 The excess of ferrous ammonium sulpliate is finally determined by titrating back with the solution of bichromate. 0-662 gram zinc dust is mixed with 80 c.c. of a solution of 25 grams KoCrjO- in a litre and 10 c.c. of dilute sulphuric acid ; after ten to fifteen minutes 10 c.c. of dilute sulphuric acid is added, and after another ten minutes the same quantity of acid added. The mixture is shaken from time to time, and finally 20 c.c. of concentrated sulphuric acid and excess (about 10 grams) of pure ferrous ammonium sulphate added. After stirring the mixture, a drop withdrawn with a glass rod must give a blue colour with a drop of potassium ferricyanide solution, other- wise a further weighed quantity of ferrous ammonium sulphate must be added. The excess of the latter salt is now titrated back witli tlie bichromate solution. The weight of bichromate reduced by the above quantity of zinc dust multiplied bj' 100 gives the percentage of metallic zinc. Example. — 0-602 gram zinc dust, SO c.c. bichromate solution (25 : 1000), 10 grams ferrous ammonium sulphate, bichromate used for titrating = 6-1 c.c. (1 gram ferrous ammonium sulphate = 0-1253 gram K„Cr.,0-), total bichromate solution used=86-l c.c. = 2-1525 K.,Cr,,0-, bichromate used by ferrous ammonium sulphate = 0-1253 x 10 =1-253 '; therefore 2-1525 - 1-253 = 0-8995 gram KoCr.,Oj is the amount reduced by the zinc, and the zinc contained in the zinc dust = 89-95 per cent. Lead Peroxide. About 10 grams of paste are weighed out and washed into a litre flask. 100 c.c. of a half-normal oxalic acid solution and 150 c.c of dilute sulphuric acid (1:3) are then added and the mixture shaken for one hour. The flask is now filled up to the mark, the contents filtered, aud 250 c.c. measured into a basin. 26S SYNTH KTir DYKSTUFFS. Distilled water ami "jO i-.c. of ililute sul|)liiiiic aciil are added, and the excess of oxalic aciil titratc(l back uitli standard permanganate solution. 1 gram crystallised oxalic acid=r8yG8 grams PbO^. Sodium Sulphide. The technical product may be rapidly tested by the volumetric method described by Battegay {Zeit. Farhen u. Texfil. Chem., 1903, 350). The solution of sodium sulphide to be analysed is treated carefully' with dilute acetic acid in presence of phenolphthaleni, till the latter is colourless, so as to neutralise any free alkali which may bo present. A standard solution of crystallised zinc sulphate is now run in from a burette till all the soluble sodium sulphide is converted into the insoluble zinc sulphide. In order to indicate the presence of still unchanged sodiimi sulphide, cadmium sulphate is used. A concentrated solution of the latter is prepared and spotted on thick white blotting-paper (not ordinary lilter-paper). A drop of the liquid being analysed is brought into contact with the cadmium sulphate, and as long as auj' soluble sulphide is present a yellow stain of cadmium sulphide will be formed. With a little practice the end point is easily found. Eu-aiiip/e. — 5'2015 grams of sodium sulphide dissolved in water up to 250 c.c. 2.5 c.c. rei|uired ; 9'4 c.c. two-fifths-normal zinc sulphate (57'514 grams ZnS0^.7H.,0 in 1 litre). n.T ,^, ' «r 9'4xO-07S Na^S m 25 c.c. = g = 0-1466 sram ; jiercentage of Na„S _ 10x0-1466x100 5T015 = ^*''^^- Sodium Nitrite. Sodium nitrite is analysed bj* the permanganate method in acid solution. jKMnO, i ..NaN0,+ 4H,S0, = 2KHS0, + -JMnSO, t oNaNO;, + ;)tt,0 The sodium nitrite solution is run from a burette into a certain c|uantitj' of permanganate solution strongly acidified with dilute sulphuric acid, which is warmed to 40-r)0°. The end of the reaction is shown hy the disappearance of the pink colour. For example : — 20 c.c. of a half-normal (or 100 c.c. of one-tenth- normal) solution of potassium ])ermanganate arc acidified with dilute sulphuric acid, warmed to the above tempcratvnc. and a solution of 1 gram of sodium nitrite in 100 c.c. of water added from a burette till the colour disappears. 1 c.c. half- normal permanganate (16 grams per litre) corresponds to 0'01725 gram sodium nitrite ; therefore 20 c.c. permanganate = 0'345 gram NaNO.,, and if n c.c. of the 3450 nitrite solution have been used, the percentage of NaNO._. = . Technical sodium nitrite is 97 to 98 per cent. NaNO., (see also Lunge, Client. Zi'i/., 1904, 501). II. ORGANIC PRODUCTS. Aliphatic Compounds. Foriiialdehijde. The commercial solution of formaldehyde in water contains about 40 per cent. CHjO. The sample for analysis is shaken with precipitated chalk, allowed lo stand. OROANIC PRODTTCTS. 269 and 5 c.c. of the clear solution added to 50 c.c. normal ammonia solution in a flask which is stoppered and allowed to stand for one day. The excess of ammonia is now titrated back with normal hydrochloric acid, using litmus as indicator. From the equation eCH^O + 4NH3 = CeHjoNj + 6H.,0 hexametliyleiie- tetramine, the above quantity of ammonia would combine with 2-4 grams formaldehyde, corresponding to a 48 per cent, solution. For each c.c. of hydrochloric acid used in titrating the excess of ammonia, 0"048 gram of formaldehyde is subtracted from this amount. If 11 c.c. of normal acid have been used, the percentage of formaldehyde = 48-nx0-96 (Legler, Ber., xvi. 1333). For a very exact method see Blank and Finkenbeiner {Ber., 1898, xxxi. 2979). Formaldehyde is used for the preparation of Auramine, triphenylmethane colours, and certain colours of the acridine series. Meihyl Alcohol. Methyl alcohol is used in the colour industry for the preparation of dimethylaniline, formaldehyde, and methyl chloride, bromide, and iodide. The chief impurity to be met with is acetone, which is tested for by Kramer's method {Ber., xiii. 1002). Into a stoppered measuring cylinder of 50-c.c. capacity, 10 c.c. of caustic soda solution (80 grams NaOH in 1 litre) are measured, then 1 c.c. of the methyl alcohol, and lastly, after shaking, 5 c.c. of iodine solution (containing 254 grams iodine in 1 litre). After standing for some time 10 c.c. of alcohol-free ether are added and the cylinder shaken. The volume of the ethereal solution is now read off, an aliquot part (about 5 c.c.) withdrawn with a pipette, transferred to a weighed watch-glass, and the ether allowed to evaporate, when the iodoform separates out as yellow crystals. The watch-glass is left in a desiccator, containing sulphuric acid, for some time and then weighed. 1 molecule acetone, C3H^;0 = 58, gives 1 molecule iodoform, CHl3 = 394. From the determination of the specific gravity (which is always made) the weight of 1 c.c. of methyl alcohol is given, and the amount of acetone contained in it easily calculated. A number of manufacturers (German) of methyl alcohol guarantee the following properties of their product : — 1. Sp. gr. not below 07995. 2. The amount of acetone not above 0-7 per cent. 3. At least 95 per cent, of the methyl alcohol must distil within one degree (65"5 to 66'5) (measured with a thermometer divided into -ji-uths of a degree). 4. If the alcohol is shaken with twice its volume of concentrated sulphuric acid, it should become, at most, light yellow. 5. Five c.c. of the alcohol should not at once decolorise 1 c.c. of a solution of potassium permanganate containing 1 gram in a litre. 6. Twenty-live c.c. must, when treated with 1 c.c. of bromine solution (1 part bromine in 80 parts of 50 per cent, acetic acid), remain yellow. 7. The methyl alcohol must remain colourless on addition of concentrated caustic soda solution. If methyl alcohol is intended for the manufacture of formaldehyde, it must be absolutely free from chlorine compounds. 270 SYXTHRTIC PYESTrFFS. Aromatic Compounds. Betizeiie. "Pure benzene " slionld distil within one degree of the correct Ijoillngiioint (80'o°). It should give no crystalline precipitate on sUinding with a few drops of phenylhj'drazine (carbon bisulphide). On shiiking with concentrated sulphuric acid, the latter should only be slightlj- darkened (tiiiophene or hydrocarbons of the ethylene series). On shaking with sulphuric acid and a fragment of isatin, no blue colour should be produced (thiophene). On treatment with a mixture of nitric and sulphuric acids and distillation with steam, no unnitrated hydrocarbon should be obtained (iivdrocarbons of the paraffin series). It should solidify on cooling below 0° (M. P. 6°). " Crude benzene " is a mixture of benzene, toluene, and a little xylene, and is known as "30s.," "50s.," or "90s.," according as 30 per cent., 50 per cent., or 90 per cent, of the whole (by volume) distils before 100° is reached. These give the following numbers on distillation : — 30s. 50s. 90s. To 85° per cent. per cent 25 per cent. » 90" 2 4 70 ,, 95° 12 26 83 „ 100° 30 50 90 „ 105° 42 62 94 „ 110° 70 71 97 „ 115° 82 82 98 » 120° 90 90 99 B3' carefully distilling 100 c.c. of the benzene from a small distilling flask and collecting the distillate in a measuring cj'linder, the quality of the product is valued by the amount which is read off when the thermometer registere 100°. (See also Frank, J. S.C.I. , 1901, 166.) For the estimation of sulphur in benzene, see Schwalbe, Zeits. Fail. Text. Ind., 1905, 113. Toluette. Commercial toluene should only be slightly darkened on shaking with concentrated sulphuric acid. It should distil within one degree (111-112°). B.P. 111.° Xylene. The three isomeric xylenes occurring in coal-t;ir arc not separated on the large scale. The commercial product should distil within a few degrees; for example: — To 138° . 10 per cent. „ 139° ■ 70 ,. „ „ 140' • '"^S ., „ l40-5° . ■ 90 „ „ ORGANIC PRODUCTS. 2/1 NaphOudene. Commercial naphthalene is nearly chemically pure. It should melt at 79'2° and boil correctly within one degree (B.P. 218°). It must be white and volatilise without residue. By shaking with concentrated sulphuric acid it must become dark-coloured. Naphthalene should not contain phenols or quiuoline bases. To test for phenols, 1-2 grams are boiled with 30 c.c. dilute caustic soda, the solution cooled and filtered from naphthalene. To the filtrate is added a little bromine water and hydrochloric acid. If phenols are present, a precipitate of bromo- phenols is obtained. Quiuoline bases are tested for by dissolving the naphthalene in concentrated sulphuric acid, pouring the solution into water, and, after filtering from naphthalene and making the filtrate alkaline, distilling in steam. Quiuoline bases distil over and are recognised by their smell. Nitrobenzene. 1. Light or pure nitrobenzene must distil between 205° and 210°, and have a sp. gr. of 1"2. 2. Heavy nitrobenzene, or "red nitrobenzene," distils betweerf 210° and 240°, and should have a sp. gr. of 118. Nitrotoluene. 1. O^-^/ionitrotolueue should boil from 222-225°. 2. Pacanitrotoluene should melt at 54°. The o?-toluidine tirst, then aniline, is precipitated, while o-toluidine i-emains in solution. The precipitated oxalates are converted into the corresponding oils, and the relation of aniline to 2^-toluidine determined by titration with the bromine solution. /. Determination of aniline, a- and p-toluidine, and aniline in mixtures with 0- or p-toluidine or both tolnidines. — The " bromine " solution is prepared by boiling a mixture of 480 grams of bromine, 336 grams potassium hydrate (100 per cent.), :ind 1 litre of water for two to three hours. The solution is diluted to 9 litres. For standardising this solution, as well as for analysis, 1-5-2 grams of oil are dissolved in 100 c.c. of hydrobromic acid of sp. gr. 1-45-1 "48 (or the corresponding quantity of potassium bromide and hydrochloric acid) and 1000 c.c. of distilled water, and the "bromine" solution added till starch- iodide paper shows a blue colour (presence of bromine). The titre of the solution is obtained with pure aniline. The amount of aniline in technical aniline oil is given by the formula 'l-'iinot- r377« and percentage = .rlOO where x is the quantity of aniline in the quantity a of oil taken, o the c.c. of bromine solution used, and t the aniline titre of the latter (weight of aniline in 1 c.c). a - X is the quantity of toluidine in the oil. //. Determination of p-toluidine in mixtures with aniline or o-tolnidine or both bases. — Tn order to obtain exact results more oxalic acid must be used than 2 74 SYNTHETIC DYESTL'FFS. corresponds to the ;)-toluidine present in the oil. This must, therefore, be roufjhlj' determined l)y a preliminary experiment. If 100 grams are taken for analysis, the amount of ;)-toluidine found in the preliminary experiment is increased by 10 grams in the case of oils containing little aniline, and 20 grains when more aniline is present, for the purpose of calculating the amount of oxalic acid to be used. The analysis is carried out in the following manner : — 100 grams oil are mixed with lOG grams of hydrochloric acid (free from sulphuric) of 31 per cent. HCl (or a corresponding amount). This mixture is at once treated with the boiling solution of oxalic acid in ten times its weight of distilled water. The solution must be quite clear when just prepared. It is now allowed to cool and left for forty-eight hours, when the oxalates of ;j-toluidine (C-H„N.C.,HoO^) and aniline have crystallised out, and are filtered, washed with 25 c.c. of distilled water three times, and decomposed by adding to a hot dilute solution of caustic potash (45 grams KOH, 250 c.c. distilled water). After cooling, the oil is separated and weighed. It is then dried with quicklime, and the amount of aniline determined as above b}' titration with bromine solution. A simple calculatiou gives the amount of p-toluidine in the original oil, to which a correction of +2'00 must be added. A modification of Keinhardt's process is given by Schaposchnikofi' and Sachnowsky (/. Russ. Chem. Soc, 1903, xxxv. 72; also J.C.S., 1903, xxxiv. 395, and Zeit, Farb. Text. Chem., 1903, 7), which depends ou the bromination of the two amines (aniline and toluidinc) by potassiiuii brouiate in hj-drobromic acid solution. The potassium bromate used is the recrystalliscd commercial product, of which an 8 per cent, solution is prepared, the strenf;th being determined by mixing 25 c.c. with 5 grams of potassium iodide and 3 c.c. of 25 per cent, hydrobromic acid solution, and estimating, by titration with standard thio- sulphatc, the iodine set free according to the equation KBrOg + GHBr + GKI = 31, + 7KBr + 3H.jO. 1 gram of iodine corresponds with 0-22083 gram of potassium bromate, that is, with 0-12231 gram of aniline, or 0'14061 gram of toluidine. About 1 gram of the aniline oil is dissolved in about 60 grams of 25 per cent. hydrobromic acid solution, and the bromate solution run in until the clear liquid above the bromide precipitate assumes a yellow coloration. Then, if a is the weight of oil taken, n the number of c.c. of bromate solution employed, <„ and t, the amounts of aniline and toluidine respectively corresponding with 1 c.c. of the bromate solution, the percentage of aniline in the oil is given by , — —. — '- , and that of the tuluidme by -^ —i-' • Dimetlnjlaniiine. I!.P. 192°; sp. gr. 0-9553 at 15°. The commercial product is usually nearly pure. The chief impurity is wo7iomethylaniline. This is estimated by mixing 5 c.c. of the oil with 5 c.c. of acetic anhydride and observing the rise of temperature ; each degree rise indicates about J per cent, of 7HO?iomethylaniline. The oil should have the correct specific gravity, and distil between 190° and 192°. ORGANIC PRODUCTS. 275 The following table shows the behaviour of two samples on distillation :— Specific Gravity at 15°. I. 0-9690. II. 0-961S. Percentage volume distilling over at iy0-191° ',! ^^^° 194° ',', .'. .. ^^^° 10 7S 6 ] 1 96 13 76 5 1 Total 95 The presence of aniline in the oil is detected by adding a drop or two of concentrated sulphuric acid to the ethereal solution. If aniline be present, a precipitate of aniline sulphate will be formed. Diethylaniline. B.P. 213-5° ; sp. gr. 0-939 at 18°. The amount of monoethylaniline is estimated as under diniethylauiline by mixing with acetic anhydride. The oil should distil to the extent of 90 per cent, between 212° and 214°. NapMlujlamine. I. a-napMlitjlamine, M.P. 50°.— The commercial product should have nearly the right melting-point, and should give a clear solution with warm dilute hydrochloric acid. II. p-naphthijl amine, il.P. 112°, should not smell of a-naphthylamine, should have nearly the correct melting-point, and should dissolve nearly completely in dilute hydrochloric acid. Other derivatives which come on the market are Naphtliylamine S, which is a-uaplithylamine sulphate ; Developer B, ethyl-;8-naphthylamine. Nitranilinpf:. The nitraniliues which are used technically are the meta, M.P. 115°, axid para, M.P. 147°. Tiiey are tested with half-normal nitrite solution. For the analysis, 1-38 grams are weighed out and dissolved in water with addition of 7 c.c. concentrated hydrochloric acid. Detection of m-nitraniline in p-nitraniline (Liebmann, J.S.C.T., xvi. 294). — 0-25 gram of ;>nitraniline is heated with hydrochloric acid and zinc dust in a flask fitted with a buusen valve till the solution is colourless. The mixture is filtered and diluted to 250 c.c. If 10 c.c. of this solution is diluted to 50 c.c, and one to two drops of a dilute solution of sodium nitrite added, a pale-yellow coloration is produced. If, however, the substance contained («-nitraniliiie, the solution becomes brown, due to the formation of Bismarck brown. 276 SYNTHETIC DYESTUFFS. yj-Xitraniline also comes cm the market in the form of its diazo-compound for the pruduction of " para "-reds. Azophor red PN is a mixture of the diazo-sulphatc with aluminium sulphate. Nitrazol is a mixture of the diazo-sulphate with sodium bisulphate. Sniphanilic Arid. The commercial product sometimes contains a little aniline. It is dissolved in water with addition of caustic soda ; the alkaline solution boiled for some time to drive off the aniline, and, after cooling and acidifying, titrated with half-normal nitrite. Xylidim'. Conimercial xylidiue is a mixture of live isomers, viz. : — ??j-xylidinu . . . . | u„ about 40 per cent. NH., CH, «-xvlidine .... | l^'^ „ 30 CH., 1 small quantities of 2araino-»«-x3'lene . . .1 i^Ho V JcH, CH, 3-amino-o xylene . ./NcH-j \/^ CH, ,ACH, and 4-aminof)-xylene NH„ The oil should boil between 210° and 220' and iiavc a sp. gr. of 0-9815-0-9840. It should give a clear solution with dilute hydrochloric acid. The meta-compound is separated by adding glacial acetic acid, and the para-, as hydrochloride, by adding hydrochloric acid to the filtrate from the m-sylidine ncGti-itc (E.i'. 11,8228"; D.P. 39,947«''. Hodgkinson and Limpach, ./.C.S., 1900, Ixxvii. 65.) o-Tvluidim'. 1?.P. 197°; sp. gr. 1-0037 at 15°. The iircsencc of aniline is detected by the prod\iction of a violet colour on shaking the ethereal solution with a solution of bleaehingpowdcr. For the estimation of ;)-toluidiue in commercial " fluid toiuidine," the method of Merz and Weith {Bar., ii. 433) is used: — 10 c.c. of the oil, which has been ORGANIC PRODUCTS. 277 dried over solid caustic potash, is heated with 10 c.c. of acetic anhydride for two hours at H0°, the product is mixed with 30 c.c. of acetic acid and poured into 800 c.c. of cold water. After standing for two days the separated para- acettoluide is filtered off, washed with dilute acetic acid (10 per cent.), dried, and weighed. From this weight the percentage of ^)-toluidine is calculated (100 acetyl compound = 71 '8 /)-toluidine). When small quantities of /)-toluidine are present (under 10 per cent.) the following colorimetric method of Schoen is used : — A standard oil is prepared containing S per cent, of ^'-toluidine and 92 per cent, of o-toluidine ; 1 c.c. of which is dissolved with 2 c.c. of pure hydrochloric acid in 50 c.c. of water, and oxidised cold by adding 1 c.c. of a saturated solution of potassium bichromate. After standing for two hours the product is filtered, the precipitate being washed with water, and the filtrate and washings made up to 100 c.c. The toluidine to be tested is treated in the same manner, and compared colorimetrically with the above solution. Commercial " pure o?'90, xxiii. 2753). — The method depends on the fact that phenol absorbs 3 atoms of iodine, i.e. 1 molecule of phenol requires 3 molecules of iodine. 2-3 grams of phenol are dissolved in caustic soda ; at least 3 molecules of alkali to 1 of phenol must be taken. The solution is diluted to 250 or 500 c.c. ; .'> or 10 c.c. measured into a small flask, and warmed to al)OUt 60°. One-tenthnormal iodine solution is now added till the liquid is coloured yellow, and the flask shaken, when a reddish-coloured precipitate is formed. The fliisk is cooled, the con- tents acidified with dilute sulphuric acid, and diluted to 250 or 500 c.c. Of this, 100 c.c. are filtered and the excess of iodine titrated with onetenth-normal sodium thiosulphate (using a few drops of starch solution as indicator). The amount of iodine absorbed by the phenol multiplied by or O'l 23568 gives the amount of phenol. See also Riegler, J.C.S., 1900, Ixxviii. 112. and Schryver, J.S.C.L, 1S99, xviii. 553. ORGANIC PRODUCTS. 279 Beiorcwol. M.P. 118°. The commercial product should be light in colour, and should not become brown on exposure to air. It should have the right melting-point, and give a clear solution with water. Water is estimated by drying over sulphuric acid. Benzaldehyde. B.P. 180°; sp. gr. 10504. The technical product must be colourless, have a sp. gr. of 1 052-1 '055, and distil completely between 176° and 180° in a stream of hydrogen (to prevent part oxidising to benzoic acid). It must give a clear mixture with concentrated sulphuric acid, and dissolve in ammonium bisulphate without leaving any oily residue. To estimate the presence of benzoic acid, .50 c.c. of the sample are shaken with 10 c.c. normal caustic soda and water, using pheuolphthalein as indicator, and the excess of caustic soda is titrated back with normal acid. 1 c.c. normal NaOH = 0'122 gram CeH-.COOH. Benzoic Acid. M.P. 120°. The technical product should be colourless and volatilise without residue. It should have the right melting-point, and give a clear solution with dilute ammonia, benzene, and ether. The strength is tested bj- titration with normal caustic soda, using litmus as indicator. On account of the slight solubility in water, it is best to add an excess of caustic soda and titrate back with one-tenth-normal acid. SaUcylic Acid. M.P. 156°. The technical product must be white and not smell of phenol. The strength is estimated by titration with normal caustic soda in the same manner as in the case of benzoic acid. The end point is reached when the salt OH \COONa is formed. The disodium salt has an alkaline reaction. Phthalic Anhydride. M.P. 128°. The technical product should form colourless needles, and have the right melting-point. It should be soluble in benzene and volatilise without leaving a residue. 2 8o SYNTHETIC DYESTUFFS. The naphihols. a-Naphthol, M.P. 94°. — Tlie technical product forms white crystalline lumps. The chief impurity is /3-naplitliol (see below). (i-Naphtliol, M.P. 121}°. — The commercial product should have nearly the right melting-poiut and dissolve almost completely in dilute caustic soda. Detection of a-naphtlwl in ji-imphthol. Method of Leger {Bull. Hoc. Cliim., xvii. 546). — A cold saturated solution of naphthol is prepared by grinding with water in a mortar and, after standing some time, filtering. On the other hand, a solution of sodium hypobrumite is prepared by dissolving 5 c.c. of bromine in a solution of 12 grams of caustic soda in 130 c.c. of water. 10 c.c. of the naphthol solution are treated witli a few drops of the hypobroraite solution, a-naphthol gives a dirty violet precipitate, while /i-naphthol gives a yellow colour. In this waj' 1 per cent, of a-naphthol in ^-naphthol may be detected. The solutions must be freshly prepared. Liebmann (J.S.C.I., 1897, xvi. 294) proceeds as follows : — 01 44 gram of the /i-naphthol is dissolved in 5 c.c. of absolute alcohol contained in a graduated test-tube, and the solution made up to 15 c.c. with pure toluene; 01 4 gram of paranitraniliue dissolved in 9 c.c. of dilute hydrochloric acid is then cooled and diazotised with 1 c.c. of normal sodium nitrite, and 1 c.c. of the diazo-solutiou added to the tube containing the /i-naphthol. Water is then added, the toluene solution separated and shaken with 5 c.c. of normid caustic soda, and the colour of the alkaline solution com- pared with that of the alkaline solution obtained in exactly the same way from /i?-naphthol containing a known quantity of a-naphthol. The test is based on the fact that the hydroxyazo-derivative obtained from a-naphthol and paranitraniline is soluble in alkalies, whereas the corresponding /i-naphthol derivative is insoluble. /8-naphthol can readily be freed from a-naphthol bj' crystallising it from toluene, washing the crystals first with a mixture of toluene and light petroleum, then with the latter alone, steaming and crystallising the steamed product several times from boiling water. Naphthol Sulplumic Acids. Certain of these acids (e.ij. Neville and Winther acid, Schafter salt, R salt, F acid) may be titrated with standard diazobenzenc solution in alkaline solution (sodium carbonate) (see p. 277); but a more accurate method is that due to Vaubel (Chem. Zeit., 1893, 1265, 1897), which depends on the fact that these acids absorb one atom of bromine. The analysis is carried o>it by titrating an acidified solution of the acid, to which potassium bromide has been added, with a solution of pota.ssiuni bromate of known strength, when bromine is liberated according to the equation oKBr^KBrOa + HHSO, = 3Br tiKHSO^ - 3H.,0 The bromine is absorbed rapidly by the naphthol sulphonic acid, and the end of the reaction is shown by starcii-iodidc paper becoming blue. The experiment is carried out at 30-40°. The potassium bromate solution is made by dissolving pure recrystallised potassium bromate ( 11 '1 4 grams) in water and making up to 1 litre. 1 c.c. of this solution = 00696 gram R salt (mol. 348) or 00492 gram Schaffer, F, or Neville and Winther acid (mol. 246). For analysis, ^\^ molecule of the naphthol sulphonic acid is weighed out, dissolved in water, acidified with a few c.c. of dilute sulphuric acid, and, after ORGANIC PRODUCTS. 28 1 adding a few crystals of potassium bromide, titrated with the solution of bromate at 40', using starch-iodide paper as indicator. The number of c.o. of bromate solution used multiplied by 2 gives the percentage. Amidonaphthol sulphonic acids are titrated with standard diazo-benzene solution in presence of sodium carbonate. Naphthijlumine Sidphonie Acids. These are tested by titration with half-normal nitrite, y^jj- molecule of the acid is weighed out {e.g. 2'45 grams of sodium naphthionate), dissolved in water (400-500 CO.), acidified with sulphuric acid, and nitrite solution run in till a reaction is obtained, after standing for five minutes, with starch iodide-paper. The number of c.c. of nitrite solution used, multiplied by 5, gives the percentage. Anthracene. M.P. 216-5°. The valuation of commercial anthracene is carried out as follows : — 1 gram of the sample is heated with 45 grams of glacial acetic acid in a flask of 500-c.c. capacity on a sand-bath. The flask is fitted with a reflux condenser about 75 cm. long, the top of which holds, by means of two rubber rings, a test-tube of about 50-c.c. capacity. A solution of 15 grams of crystallised chromic acid in 10 c.c. of glacial acetic acid and 10 c.c. of water is contained in the test-tube, and as soon as the contents of the flask are boiling the chromic acid solution is siphoned over from the test-tube into the condenser tube by means of a small capillary siphon. This is chosen of such a size that the chromic acid is siphoned over in about two hours. (This is tried beforehand.) When the test-tube is empty, the flask is boiled for two hours longer, and allowed to cool till the following day. 400 c.c. of water are then added, and the whole filtered. The residue of anthraquinone is washed, first with cold water, then with boiling alkaline water, and finally with boiling water alone, until no alkaline reaction is obtained. The filter-paper is now carefully removed from the funnel, opened out on a glass plate, and the contents washed into a small porcelain dish and dried at 100°. The crude anthraquinone is then heated to 100° with 10 grams of slightly fuming sulphuric acid for ten minutes, left till next day in a damp place, and washed into a dish with 200 c.c. of cold water. The precipitated anthraquinone is filtered off, washed with alkaline water, and finally with hot water alone ; then washed into a small dish, dried, and weighed. The dish is then heated on a sand-bath until the anthraquinone has volatilised, and is again weighed. The last weight subtracted from the first gives the weight of the anthraquinone, which, multiplied by 85'57, gives the percentage of anthracene in the sample (Luck, Ber., vi. 1347; see also Basset, Chem. News, Ixxiii. 178, Ixxix. 157). For the detection of Jlethylanthracene, see A. G. Perkin, Jour. Soc. Dyers and Colourists, 1897 ; and of Paraffin, Allen, Comm. Org. Analysis, ii. 529. Turkey -red Oil Analysis. Primary test. — The oil must react slightly alkaline or neutral ; mixed with water, a perfect emulsion must be obtained, from which oil-drops are separated after a few hours. These drops must be completely soluble in ammonia, other- wise unsaponified fat is present. 252 SYNTHETIC PYKSTPFFS. Wdfpr. — According; to Stein, 10 grams of oil are melted with "J.t grams dry parafiiii wax in about 75 c.c. saturated salt solution. The cake is dried and weighed. The increased weight of wax represents oil free from water ; the difference between 10 and the exact amount of oil used is water. Fat (total). — 100 c.c. of oil are mixed in a graduated cylinder with 20 c.c. hydrochloric acid (concentrated), and then n)ade up with saturated salt solution to 500 c.c. The whole is shaken freciuently and slightly heated. On ct)oling, the fat swims on the salt solution. The number of c.c.'s shows direct the total amount of fat. (This is sufficiently accurate for practical purposes.) CHAPTER XXXI. THE APPLICATION OF THE COLOURING MATTERS. (1) The Behaviour of the Ppincipal Fibres towards Reagents. Before dealing with tlie application of the djestufts to the fibres on the experimental scale, it will be necessary to briefly discnss the more important properties of the textile fibres, since it is upon the nature of the fibre that its behaviour towards the colouring matters mainly depends. The textile fibres may be classed under the following heads : — I. Nitrogenous fibres are of animal origin, and the two most important members are wool and silk. They are characterised by being readily disintegrated by alkalies, by which the non-nitrogenous fibres are unattacked ; but are more resistant than these towards acids. II. Non-nitrogenous fibres are of vegetable origin, and consist of cotton, flax, hemp, jute, etc. The reactions of these two important groups are readily seen by the following table : — Reagent. Nitrogenous (Animal). Non-nitrogenous (Vegetable). Alkalies (NaOH, 12° Tw.), . Dissolved. Undissolved. Acids (KSOj 1:3), . Undissolved. Dissolved. Ignition, .... Burns slowly, gives off a smell Burns rapidly, gives off a of burnt horn, and fuses to a smell of burnt paper, and small bead of hard porous leaves behind a loose carbon. white ash. Strong H^SOj and iodine, Unaltered. Stained blue. Zinc iodochloride,* Unaltered. Stained violet. Boiled with lead oxide and Blackens t Unaltered in colour. caustic potash * A concentrated aqueous solution of zinc chloride is added to a solution of iodine in potassium iodide, the following proportions being taken : — 1 pt. I, 5 pts. KI, 30 pts. ZnCL, 14 pts. H.p. + Owing to the formation of lead sulphide, due to the presence of sulphur in the animal fibre. (2) Experimental Dyeing". The valuation of the individual members of the various groups of the synthetic dyestuti's is at the present time, with few exceptions, merely a matter of comparison with types, a comparison which is usually carried out either (1) By colorimetric tests, or (2) By comparative dye-trials. 284 SYNTHETIC DYKSTUFFS. In the first case the comparison is brought about bv dissolving equal amounts of tlie samples under examination in water, and comparing the colour of the solution produced, in a specially devised ap|>aratus known as the colorimeter. In the second, equal weights of some fibre are dyed in solutions containing known quantities of the samples to be compared, under precisely the same conditions, and the ditt'erencc in the resulting shades noted. This second process is by far the most generally used, since it enables the dyer to ascertain the relative purity of any ."sample which he luay wish to examine, and is, moreover, tlic only really reliable one, since the chemical analyses of dyestutt's, except in a few ca.ses which will be dealt with later, cannot be accurately ett'ected, owing to the many substances which occur in them as impurities, accidental or otherwise. The knowledge, therefore, of the methods by which experimental dyeings may be produced on the fibre is essential, not only to the works chemist, but also to the research chemist, who may wish by its means to ascertain the relative importance of any colouring matter with which he may come in contact. Again, the value of a dyestuft' depends to a very considerable extent upon its behaviour towards reagents, both in the free state and upon the fibre. In the ensuing pages will be found tests by which their Itehaviour in this respect can be ascertained. Standard solutions of dyestufTs.— In order to facilitate the employ- ment of the small (luaiititios of the colouring matters necessary in dye-trials, it is usual to prepare a stanye in the same way in a boiled-otf liquor bath con- taining the requisite quantity of dye solution slightly acidified with acetic acid. The temperature should be raised to 80°, and maintained at this until no more dye is absorbed. After dyeing, wash and pass through acidulated water. (3) Subftantire cotton ilyeatujlk — Enter the fibre cold and then dye, boiling with an addition of 15 per cent, neutral sodium sidphate and ."> per cent. soap. After dyeing, pass through dilute acid ; wash and dry. Cotton dyeing-.— I. Substantive Cotton Dyestuffs. The dyeing of cotton with these dyestuffs is brought about by heating the weighed material in a slightly alkaline bath containing the required quantity of dye solution (usually 3 per cent.), together with a quantity of sodium chloride, depending upon the quantity of the colouring matter and its affinity for the fibre. THE APPLICATION OF THE COLOURING MATTERS. 287 Thus colouring matters which do not exhaust readily — that is, are not extracted readilj' by the fibre from the bath — require a proportionately large amount of salt. Care must be taken, however, not to add too much salt, otherwise the dyestuff may be precipitated from its solution and cause unevenness in the dyeing. A typical example may be given as follows : — Enter the cotton into a bath containing 20 per cent, neutral sodium sulphate, 2 per cent, sodium carbonate, and 30 per cent, sodium chloride at 60°, then heat gradually to boiling, and maintain at this temperature until no further absorption takes place (usually one to one and a half hours). All dyeings on cotton with the substantive cotton dyes are more or less fugitive. Their fastness may be increased by the following processes : — (1) Diazotising and developing. (2) After-treatment with copper sulphate. (3) After-treatment with bichromate of potash and copper sulphate. (1) Diazotising and developing. — This method applies only to those sub- stantive cotton dyes that contain a diazotisable amido-group ; it is carried out as follows : — The dyed material is passed through a bath containing 1 gram .sodium nitrite (previously dissolved in water), ) , t 1 it • 2i c.c. sulphuric acid, 168° Tw. (sp. gr. 1'84), J P ' in which it should be worked for fifteen minutes, then rinsed and immediately entered into a cold solution of the developer. The following developing baths can be used according to the shade desired : — 5 grams ^-naphthol, 5 ,, caustic soda, 76° Tw. (sp. gr. 1"38), 1 litre of water ; ■T grams resorcinol, 10 ,, caustic soda, 76° Tw. (sp gr. 1'38), 1 litre of water ; and 5 grams toluyleuediamine hydrochloride, 10 „ crystalline sodium carbonate, 1 litre of water, the diazotised material being worked in the bath for about fifteen minutes, then washed and dried. (2) After-treatment with copper sulphate. — ilany substantive cotton dyes are rendered faster if their dyeings are subsequently treated with a solu- tion of copper sulphate, although in many cases the shades are considerably deteriorated thereby. The process consists in passing the dyed material through a bath heated to 100° containing 3 per cent, sulphate of copper solution. The treatment should last half an hour. 288 SYNTHETIC DYESTUFFS. (3) After-treatment with bichromate of potash and copper sulphate. — The addition nf liichrnniute of putasii in some cases yields better results than suljihate of cupper alone. The following bath mux be used : — ■5-1 percent, biciironiate, 1 I'.'i-S „ co])per sulphate, on the weight of material. ■5-1 „ acetic acid, 30 i)er cent., I The after-treatment can also be ap|)lied to diazotised and developed dyeings. II. Dyes Developed Directly on the Cotton Fibre. To this class belong certain insoluble azo-conipounds which are produced by immersing the fibre impregnated with a second component in a bath containing a .solution of the diazo-salt of the lirst component. A typical example is ^-Nitraniline red, which is produced by combining /j-naphthol (on the fibre) with diazo-/)-nitraniline chloride. Treating with fi-Haphthol. — The cotton is passed through the following solu- tion (for 10 grams of cotton) : — j 10 grams /j-naphthol, V 10 „ caustic soda .solution, 77° Tw. (sp. gr. 1385), ( 100 c.c. boiling water, I 25 grams Turkey-red oil, \ 100 c.c. boiling water. mixed together and diluted to 1 litre. It should be thoroughly worked for from five to ten minutes in the luke- warm liquid (40"), then wrung out and dried in the drying cupboard by means of hot air. When thoroughly dry, the fibre should be developed without loss of time, since it rapidh" becomes brown on exposure. Developing. — Solution A. 15 grams />-nitraniline are mixed with 36 c.c. boiling distilled water, and dissolved with 32 c.c. hydrochloric acid, 32° Tw. (sp. gr. IIG). riiis acid solution is run in a thin stream with constant stirring into 225 c.c. of water, which should be cooled by means of lumps of ice. The ^)-nitraniline hydrochloride separates out in the form of tine yellow crystals. After the solution has euoled to not more than 12°, 8 grams of nitrite of soda dissolved in 24 c.c. of cold water are poured in, and after remaining ten minutes the whole diluted to 400 c.c. with cold water. SOLOTION B. 8 c.c. caustic soda solution, 77° Tw. (sp. gr. 1-385), are diluted with cold water to 7G ,, and mixed with a solution of 20 grams acetjitc of soda in 76 c.c. of cold water. THE APPLICATION OF THE COLOURING MATTERS. 289 The developing bath is made by mixing 7 parts of solution A with 3 parts of solution B, the solution being kept cold by means of ice. The dye is formed by passing the prepared cotton, which should be quite dry, through the developing solution, in which it should bo worked for about one minute, then wrung out and again worked for one minute, after which it should be thoroughly rinsed, and finally washed in a boiling soap solution. III. Basic Coloiu-ing Mattel's on Cotton. The property possessed by the l)asic colouring matters of forming insoluble lakes with tannic acid is taken advantage of in dyeing them on the cotton fibre. The process consists in first treating the fibre with tannic acid, upon which it is fixed by means of tartar emetic, and then steeping the cotton thus mordanted in a solution of the basic dyestuft'. Mordanting : Tannic acid solution. — The cotton is worked in a bath con- taining 21 to 5 per cent, of tannic acid (on the weight of material) at a tempera- ture of 50° for about fifteen minutes, after which it is allowed to remain in the bath for six hours. Without rinsing, it is then worked for one-quarter of an hour in a cold bath containing 2J per cent, tartar emetic or lA per cent, fluoride of antimony, after which it should be thoroughly washed and wrung out. In each case the quantity of solution should be adapted to the quantity of fibre ; for 10 grams 500 c.c. will be found a convenient amount. Dyeing. — Enter the mordanted fibre into a cold solution of the requisite quantity of dyestuft', and work whilst slowly raising the temperature to 70° ; keep at this temperature until all colouring matter has been absorbed. The fastness of the colour can be increased by subsequently passing the dyed material through the tannic acid solution. Certain basic dyestufts — for example, the Khodamines — give only poor shades of colour on tannin mordant. The brilliant pink colour of these dyestuffs can, however, be produced on cotton by using a mixed mordant of Turkey-red oil and aluminium acetate in the following way : — Mordanting. — Work the fibre for fifteen minutes in a solution containing 1 part of Turkey-red oil and 9 parts of water, wring out and dry in hot-air cupboard ; then pass several times through a solution of acetate of alumina, 10° Tw., wring out and dry. Both operations should then be again repeated in the same manner. Dyeing. —As above. IV. Acid Colom-ing Matters on Cotton. Tlie acid colouring matters (except the substantive cotton dyes) are not well adapted for the dyeing of cotton. A fugitive colour can, liowever, be produced by dyeing in a concentrated bath containing alum or stannic chloride. The Eosines, etc., can be dyed upon cotton from a bath containing a large quantity of common salt. 19 290 SYNTHETIC 1>YESTUFFS. V. The Sulphur Dyestuffs on Cotton. Tlic cotton filire is dyud with tliese dyestufts from a bath containing tliem dissolved in a sohition ol' sodium sulphide. The hatli is prepared by boihng a sohition containing the requisite quantity of soHd dyestuH', 2 to 3 per cent, sodium carbonate, 5 to 10 per cent, crystallised sodium sulphide, and 10 per cent, sodium chloride or Glauber's salt. The fibre is entered into the boiling bath and worked until finished. It is essential tiiat, after dj'cing, the cotton should be thoroughly washed before drying. The fastness of the sulphur colours may be increased by after-treatment with (1) Chromium salts. (2) Acetate of soda. (3) Peroxides of hydrogen or sodium. (4) Steaming, with admission of air. VI. The Production of the Vat-Colours on Cotton and Wool. The most important dyestufV of this class is Indigo, which is produced upon the fibre by th-at treating it with an alkaline solution of Indigo white, which, on oxidation in the air, is reconverted into the blue. The term "vat" applies to the vessel employed for dissolving the Indigo, and also to the solution itself, which may be prepared by the aid of various reducing agents. Two only need be considered here— (1) The zinc vat for cotton. (2) The hyposulphite vat for wool and cotton. The zinc vat for cotton. — 50 grams liidigo (20 per cent, paste). 10 „ zinc dust. 30 „ unslaked lime. Mix the zinc dust with 120 c.c. of water at 50°; add the Indigo paste, and then the lime with constant stirring. The whole is left to stand for five to six hours, but is stirred from time to time. The reduction is complete when a drop of the solution placed upon a sheet of glass runs off as a j'ellow liquid which oxidises in the air in the course of forty to fifty seconds. The reduced solution is then diluted with 500 c.c. of water, and the cotton fibre dyed in it by being thoroughly soaked, wrung out, and dried in the air. The process is repeated until the requisite shade of blue is obtained. The hyposulphite vat (for cotton).— This vat is based on the property of hyposul|)liurous iicid, H.,SoOj, discovered by Schiitzenberger, of forming with Indigo a coloin-less double compound which is soluble in alkalies, and is decom- posed by the weakest oxidising agents, Indigo blue being tiiercby liberated. For practical use the sodium salt of liyposulphurous acid. Na„S.,Oj, is ])repared bv allowing zinc dust to act on sodium bisulphite solution in a tightly closed vessel, the mixture bcins; kept stirred and cooled. The reaction is usually com- plete within four to five hours. The hyposulphite solution is rendered slightly alkaline with milk of lime, in order to diminish its instability, and is then ready for use. THR APPLICATION OF THE COLOTTRTNG MATTERS. 29 1 Preparation of the hyposulphite solution. — 100 parts of sodium bisulphite solution, 71-4° T\v. (sp. gr. 1-358), are diluted with 225 ,, of cold water, and in the course of half an hour 8J „ of zinc dust stirred into this solution. The whole, which is stirred from time to time, is left to stand four to five hours, and then mixed with 11 J „ of lime slaked in 30 „ of watei'. After allowing the sediment to settle the clear solution is decanted and 7 „ caustic soda solution, 36° Tw. (sp. gr. TIS), added. The hyposulphite solution is now ready for use, and should be kept in a well-closed vessel in a dark room. It should show a specific gravity represented by 19-20° Tw. (sp. gr. 1 ■095-1 '1). Hyposulphite vat. — 5 parts Indigo (20 per cent, paste) are mixed with 3 „ hot water ; to this mixture 8|- „ caustic soda solution, 76° Tw. (sp. gr. 138), are added, and the whole well stirred ; after heating to 50° 25 „ of hyposulphite solution, 20° Tw. (sp. gr. Tl), are added, and the temperature kept at 50^ In the course of the reduction which takes place, and which is tested in the usual way with a sheet of glass, more hyposulphite solution is added in several portions. The reduced Indigo ought to run oft' the sheet of glass as a yellow liquid which oxidises in twenty to thirty seconds. The cotton fibre is then dyed in the same manner as indicated in the case of the zinc vat. The hyposulphite vat (for wool). — The process is essentially the same, only the use of caustic soda in the above preparations must be replaced by milk of lime. Thus the hyposulphite solution is rendered alkaline by the addition of the requisite quantity of milk of lime, and the vat is prepared by treating 5 parts Indigo (20 per cent, paste) with i parts hyposulphite solution at 80°. Of the resulting yellow-brown solution, a definite quantit}', depending on the depth of blue desired, is added to the vat, together with more hyposulphite solution. Wool is dyed in this vat at 50-60°, a temperature that must not be exceeded by more than a few degrees. VII. The Mordant Dyestuffs on Cotton. Essentially this process consists in first mordanting the cotton fibre by steeping it in a solution of the acetate of some metal, which, on subsequent steaming, remains on the fibre in the form of the oxide or hydroxide. The cotton thus mordanted is then boiled in an aqueous solution or emulsion of the mordant dyestufl', when the corresponding metallic lake is precipitated on the fibre. Another process consists in precipitating the hj-droxides upon the fibre in the form of insoluble taunates or fatty-acid salts, by first steeping the cotton in tannic acid or fatty acid, and then treating it with the metallic salt used as a mordant. 292 SYNTHETIC DYESTrFFS. The more important mordants for cotton are : — I. Alumina mordants, II. Iron mordants, III. Chrome mordants, and IV. Tin mordants. I. Alumina mordants. — The most usual form in which this mordant is applied to the cotton fibre is as aluminium acetate, which is prepared either by dissolving aluminium liydro.xide in acetic acid or by decomposing alum or aluminium sulphate with lead acetate. It is immaterial whether aluminium potas-sium sulphate (ahun), Al.,(SOj);.K.,SO^, or the normal aluminium sulphuli', AL,(SOj)3, is used in this preparation : the only point about which it i.s necessary to be certain is that no iron is present as im])urity. The following is a method for preparing a solution of aluminium acetate, 9° Tw. :— Dissolve 500 grams of lead acetate in 500 c.c. of boiling water, and mix it hot with a solution containing 505 grams aluminium sulphate (free from Fe) dissolved in 500 c.c. of boiling water. Allow the precipitated lead sulphate to settle, decant clear liquid, and dilute until it sliows a specific gravity of 9° Tw. (sp. gr. r04r)). For use as a mordant it is unnecessary that the whole of the sulphuric acid present in aluminium sul{)hate should be precipitated ; in fact it is preferable in practice to select for the preparation those projjortious which would produce a sulphacetate according to tlic equation AL,(S0,), + 2Pb(C.3;30„)., -^ ALSOj(C.aA)4 + 2PbS04 Turkey-red upon cotton. — The name Turkey-red is applied to the colour produced upon cotton by the aid of Alizarine, ahuniua, lime, and fatty-acid compounds. A considerable amount of work has been done upon the nature and formation of this colour lake. Hoseustiehl first found that the formation of the lake from Alizarine and ahnnina could not take place except in the presence of lime ; this was subseipiently confirmed by Liechti and Suida, who found that all Turkey red dyeings contain lime. Acconlini; to i.ieciiti and Suida a "normal red" has the composition Ai,03.CaO(C„H,0,,),. riie part played by the fatty acids in Turkey-red dyeing has not yet been clearly defined. Turkey red oil is prepared by treating olive oil or castor oil with concentrated sulphuric acid, usually 3 parts of acid being added to 10 parts of oil. The acid is slowly poured into the oil with coustiint stirring, and the whole then left to stand until a sample of the jiroduct is found to dissolve completely in water, whereupon it is poured into water and washed with a solution of sodium chloride until free from sulphuric acid. During the process of mixing, the temperature should not be allowed to rise above 40°, otherwise a cojiious evolution of sulphur dioxide will ensue, and the product will be dark in colour and furnish poor results on dyeing. Dijeiivj. — The production of a good Turkey-red upon cotton can only be attained by practice ; the following directions should, however, yield fairly good results if carefully followed. Cleaning. — Free the cotton fibre from grease, etc., bj- boiling it in a weak solution of sodium carbonate ; wring out thoroughly. THE APPLICATIOX OF THE COLOURTXO MATTERS. 293 Oiling. — Without drying, enter into a bath containing 10 parts Turkey-red oil, 90 ,, water, and work until thoroughly soaked. Wring out and drv in the hot-air cupboard at 40-50°. Repeat this treatment twice, drying between each immersion. Alumina mordant. — Work the fibre thoroughh' in a bath of aluminium acetate, 9° Tw. (sp. gr. r04.5) ; wring out and dry at 40-.50°. Repeat this treatment. Chalkinij. — Enter the cotton into a bath containing 6 grams of chalk and 1 litre of water at 30-40°. Stir well for about half an hour, and then wash thoroughly in clean water. It is unnecessary to dry the cotton before dj-eiug. Dyeing. — The water used should show two to three degrees of hardness ; the quantity of dyestutf should be 1'5 grams of Alizarine (20 per cent, paste) for 10 grams of cotton. Stir the dyestutf into the water and enter the cotton at 20-25°. Work the fibre at this temperature for about twenty minutes, and then heat up so that in about half au hour the temperature rises to 60°. Keep at this point for about an hour, then wring well and dry. Steaming. — Steam the dried cotton for one hour at a pressure of one atmos- phere, or for two hours without pressure ; then wash well. Brightening. — Brighten the dyed material in a closed apparatus at a pressure of halt an atmosphere ; use a solution containing 4 '5 grams of soap in 1 litre of water; leave the cotton in it for ten minutes, and wash 'well. This process ma}^ be simplified by heating the dye-bath to boiling ; subse- quent steaming then becomes unuecessarj'. The brighter shades of red are, however, obtained at the lower temperature. II. Iron Mordants play a most important part in black dyeing with logwood, and also in the production of Alizarine violet. The cotton fibre can be mordanted with iron by steeping it in ferrous sulphate solution and subsequently passing it through a solution of tannic acid. It is, however, more frequently mordanted by means of iron pyrolignate. This substance is prepared by dissolving sci-ap-iron in crude pyroligneous acid ; it consists for the most part of ferrous acetate. This compound, however, in the pure state is not a good mordant for cotton, being too readily oxidised, and, consequently, liable to be poorly fixed on the fibre. The pyrolignate, on the other hand, forms a good mordant, owing to the presence of impurities in it, which retard the oxidation of the acetate. The following indicates a method of producing Alizarine violet on the cotton fibre : — Work the material thoroughly in a bath containing 3 grams of tannic acid in 1- litre of water; wring and pass through a bath of pyrolignate of iron, 3° Tw. (sp. gr. 1'015). After washing, dye in the same manner as given in the case of Turkey -red. 294 SYNTHETIC DYKSTUFFS. III. Clii'ome mordants. — At the present time the chrome mordants are the most important in use, many f manufacture and in the daily use of the dyed material. Solubility. — This depends not merely upon the nature of the colouring matter, but also upon the condition of the water. Many dyestufls form insoluble compounds witii lime; and, therefore, if the water is hard, a portion will be precipitated owing to the formation of these insoluble bodies, and in these cases the hardness of tlie water should be corrected by the addition of sulphuric, acetic, or oxalic acids or sodium carbonate, according to the nature of the colouring matter dissolved. The solubility of a dyestutt" can be readily determined by evaporating a measured quantity of its concentrated aqueous solution to dryness in a weighed platinum vessel. Equalising' power depends upon the alKuitj- of the colouring matter for the librc. The greater or less the affinity, the more quickly or slowly- the dye-bath is exhausted. Colours which are absorbed rapidly do not, as a rule, dye evenlj', but are generally faster to washing ; whilst colours which are only slowly taken up by the fibre yield more even dyeings. This rule, in general, holds good for all coloiu's and for all fibres. The addition of sodium sulphate (Glauber's salt) to the dye-bath usually has the effect of preventing the too rapid absorption of a colouring matter possessing strong alfinities for the fibre. Of the acid dyestuffs, the yellow and orange colours are distinguished bj' their equalising powers ; whereas the reds, blues, violets, and blacks are, as a rule, inferior in this respect. Level dyeings can, however, always be obtained by a careful raising of the temperature of the dye-bath ; this is particularly the case with the basic colouring matters, wliicli possess a ver}' strong atSnity for the cotton fibre mordanted with tannin. The following experiment (v. Georgievics, Chemical Technologt/ of the Textile Fibre.'', Eng. Trans., p. 134) will indicate roughly the equalising power of a dyestuflf : — THE VALUATION OF A COLOURING MATTER. 297 Dye a sample of the fibre in the requisite quantity of the solution of a dye- stuff to dye it, say, 2 per cent. ; but in the first instance bind a portion of the fibre in such a manner that the bound portion does not come in contact with the dye solution. Wlien equilibrium has been attained, unbind the bound portion and again immerse in the dye-bath ; if the dyestufF has good equalising properties, the portion which had been bound will rapidly assume the same colour as the other portion of the fibre, and, after a short boiling, will be indistinguishable from it. If, however, the dyestuff has not good equalising power, the portion previously bound will remain lighter in shade than the surrounding fibre. Fastness. The behaviour of the colouring matters on the fibre towards chemical and physical influences, or, in other words, their fastness, depends not alone upon their nature, but also upon the nature of the fibre and the method of dyeing employed, so that one and the same colouring matter, dj-ed upon ditlerent fibres, or in accordance with ditt'erent methods upon the same fibre, may show very different properties. Fastness to ligrht. — Upon this most important property depends largely the usefulness or otherwise of any particular colouring matter. Dyes which show an extreme sensitiveness to light are useless, or can only be used to a very limited extent. The red, yellow, brown, and black dyes, as a rule, surpass the green, blue, and violet dyes in this respect. Amongst the former are a number which will withstand an exposure of several summer months almost without change ; the latter show, however, a greater inclination to fade. The basic dyes are, on the whole, fugitive to light ; but, on the other hand, there are among the acid dyes and the substantive cotton dyes products showing extraordinary resistance against the action of light, surpassing in this respect many of the natural colouring matters. The fastness of any particular dyestuft' to light can be determined by exposing samples dyed with it in photographic printing frames to the action of sunlight, half of the dyed fibre being covered by some non-translucent material. A comparison of the covered with the uncovered portions will determine the relative light- fastness of the dyestutf in question. Fastness to washing and milling-. — In an examination of a colouring matter with regard to these properties, not only the alteration in shade, but also their " bleeding " into white or coloured material must be taken into consideration. The degree to which a colour bleeds is not directly proportional to the amount which it loses in depth, but depends rather upon the affinity of the dye in question for the fibre washed simultaneously. Thus many acid wool dyes, which lose much colour when washed, bleed some- what on to the wool fibre, but not, or only very slightly, on to the vegetable fibre. On the other hand, the substantive colouring matters, if they are not after- treated according to one or another of the methods stated above, without exception bleed into white cotton, even though these often lose very little colour on washing. Washing test. — The pattern is plaited or mixed with undyed material, worked for about five minutes in a soap solution containing .5 grams of soap in 1 litre 290 SYN'THKTIC DYESTCFFS. of water at 40°, and then allowed lu leiuain in tiie sulutiou for about fifteen minutes. It is then rinsed in clean water and dried. A more severe test would consist in adding sodium carbonate to the soap bath, and using a higher temperature. Milling ie.'i:, 1880, xiii. 1840; 1889, xxii. G34, 2062. 7'he Titration of Azo-dyestuffs toith Titamm^ Chlvriile. (Knecht, J. Soe. Dyers and Colourists, 1903, No. 6, vol. xix.) This method consists in titrating the azo-dj-estuff with a solution of titanous chloride, the calculation being based upon the eijuation TiCl, + HCl -> TiClj^ H from which it follows that each azo-group ( - N : N - ) requires 4TiCl3 (or 4Fe) for its complete reduction. Siiiriiuj ami .le the analysis of Erythrosiue by means of a standard solution of Rosuniline liydrochloridc. THE ANALYSIS OF D\ESTUFFS. 3O9 Sodium chloride can be estimated by extracting the colouring matter with some organic solvent, such as acetone or alcohol, and subsequently determining the chlorine in the residue. Sodium sulphate nearly always occurs in the azo-dyestufts. It can be detected by dissolving the colour in water, precipitating by means of salt (free from sulphate), and then testing for sulphate in the filtrate. Mai/nesium sulphate is little used ; it is tested for in the same way as sodium sulphate. Alkaline carbonate occurs frequently in dyestufl's of the phthalein group. It is estimated by determining the quantity' of CO., liberated by acids. Dextrine is often added to the artificial colouring matters. It can be detected by its characteristic smell when the colour is dissolved in water. Generally speaking, it can be isolated by treating the dyestufF with alcohol in which dextrine is insoluble. Tlie determination of the acid constituent of basic dyestuffs {usnallj hydrochloric acid, although other acids, such as, for instance, oxalic acids, are used). — The colour is precipitated by ammonia, filtered, and the acid tested for in the filtrate. In the case of colours not precipitated by ammonia, such as Safranine, the acid must be tested for in the dyestuff solution. The presence of a zinc chloride double salt can be detected by igniting the dyestufF and investigating the residue. The determination of the basic constituent of acid dyestuffs is carried out in the same way, the acid dyestufF being treated with HCl, filtered, and the base tested for in the filtrate. Tlie determination of the nature of a dyestuff. — In order to determine whether a dyestufF is a mixture or a homogeneous substance, it is usually sufficient to place a small quantity of it on the end of a spatula, and then to blow it from some distance away on to a sheet of filter-paper moistened with water or alcohol. The particles of dyestufF will settle on the moistened paper, and will immediately begin to dissolve, imparting to the filter-paper its own particular colour. The homogeneous nature or otherwise of the dyestufF is easily detected by noticing the colours produced by the different particles. When two colouring matters are present which possess a similar shade, and therefore are not readily detected by this means, it will be frequently found sufficient to blow the dyestufF on to a small quantity of strong sulphuric acid contained in a white porcelain basin, and note any difference in colour produced by the solution of the dift'erent particles. Sometimes the difterent components of a mixture are very intimately mixed ; that is to say, they have either lieen precipitated together from their solutions, or have been formed by evaporating their solutions to dryness. In these cases some little difficulty will be experienced in detecting any difference in colour in the spots produced by the above methods, and recourse must then be had to the dye-trial. This is effected by dyeing a fibre in the solution of the dyestuff for a short time, then removing it and replacing it by another piece of the same fibre, this process being repeated until the dye-bath is completely ex- tracted. Since it is rare that two dyestuffs have the same affinity for the fibre, the presence of a mixture will be clearly noticeable on comparing the different dyeings (see also p. 3i3). In the following tables are given the principal behaviour of typical dyestuffs towards reagents, one or two members of each group being taken and their reactions described. 3IO SYNTHETIC DYESTUFFS. By this means a certain idea of tlie reactions of other members of the same j,'roup can he dcriveil, alliioiigh tests of tliis kind are hy no means absolute, and can only lie taken as indicating tlie possible nature of a compound. The tests have been applied to the pure dyestufts, and the commercial product should be as far as possible freed from impurities before being treated with the reagents. In many cases, by selecting suitable reactions, it may be found possible to separate the constituents of a mixture, and to isolate them in such a manner that each can be identified with certainty. For investij^ations of this kind, however, it is impossible to give rules which are generally applicable, and much practice and manipulative skill is required in oider to obtain accurate results. If the colouring matter to be examined is in solid or powder form, it is dissolved in a thousand times its weight of water; in the case of paste colours a larger (luantity is taken, according to the percentage of dry substance they contain. If the colouring matter is soluble, either entirely or nearly so, the solution is filtered, so that in the event of any turbidity or precipitation occurring during examination there need be no doubt upon tlic point. If, however, the colouring matter is sparingly soluble, or altogether insoluble, the tests arc made with a mixture of the finely divided colouring matter held in suspension in water (1 ; 1000). Only when tests are made to determine the solubility of the colouring matter in alcohol, ether, and benzene, or to study its behaviour with concentrated stdphuric acid, is it necessary to use it in the dry condition. When making these solubility tests about '1 gram of the colouring matter is added to 20 c.c. of the necessarj' reagent ; the mixture is then well shaken, boiled, and filtered. When concentrated sulphuric acid is used it is also desirable not to take too much colouring matter, so that the colour of the solution may not be too dark ; a portion of the solution is then poured into a test-tube containing cold water and the ell'ect noted. With respect to the reactions with other acids, also with alkalies and salts, equal amounts of colour solution and the reagent are mixed together in a test- tube ; one-half of the mixture is allowed to stand in the cold, and if precipitation takes place it is filtered ; the remainder is heated to boiling, note being taken of any changes which occur. For reducing with zinc dust in conjunction with acids or alkalies, 20 c.c. of the colour solution are mixed with about 5 grams of zinc dust, then about 20 c.c. of acid or alkali are added, and the whole is well shaken, then boiled till decolorised, and at once filtered, after which one must observe whether or not the filtrate becomes coloured on exposure to the air. This can be effected by spotting a piece of filter-paper with the solution and allowing it to slowly dry in the air. Since the common salt which accompanies dycstufl's which have been recrystallised from salt solutions is extremely difficult to remove by recrystallisa- tion, a small quantity of hydrochloric acid gas will frequently be given off' in testing with concentrated snl])huric acid. This is usually the case with the soluble azo-coiiipnunds. Reagents. Water, Distilled. Alcohol, Absolute. Kther, ...... Clutnically pure. Benzene, ..... „ Sulphuric acid, .... Concentrated. THE ANALYSIS OF DYESTUFFS. Sulphuric acid (dilute), . Hydrochloric acid (dilute), Nitric acid, . Sodium hydrate, . Ammonia, Sodium carbonate, . ,, acetate. Tannin solution, Alum, . Potassium bichromate. Ferric chloride, Stannous chloride, . Calcium hypochlorite. Acetic acid. . 100 grams concentrated in 1 litre water. 100 c.c. concentrated acid (sp. gr. ri6) diluted to 1 litre. 100 c.c. pure nitric acid diluted to 1 litre. 100 c.c. sodium hydrate solution (sp. gr. 1-3) diluted to 1 litre. Commercial ammonia (sp. gr. "951). 100 grams (cryst.) in 1 litre of water. 100 grams (cryst.) ,, ,, ,, 100 grams tannic acid dissolved in 500 c.c. of water and mixed with 100 grams sodium acetate in 500 c.c. of water. 50 grams (cryst.) in 1 litre of water. 50 grams „ ,, ,, ,, 100 grams ,, „ „ ,, 100 grams „ ,. ,, ,, li-° Tw. (sp. gr. 1 007), freshly prepared. 12° Tw. (sp. gr. 1-06). [Tables 3'2 SYNTHETIC DYESTUFFS. The Nitro-dyestuffs. Colouring matter, . Naphihol yellow S." Pierie acid. OK OH VO2 NO./ IfO.j \/ Description, . Bright yellow powder. Yellow crystals. /Water, .9 Readily soluble. Readily soluble. S> Alcohol, . Somewhat soluble. Readily soluble. il Ether, Insoluble. Readily soluble. " I Benzene, . Insoluble. Readily soluble. Heating on platinum foil, Explodes, leaving residue of potassium carbonate. Explodes with a luminous (lame. Cone. H.SOj, . Dissolves with yellow - green colour ; on dilution with water, becomes pale yellow ; on heating, cone, solution becomes olive-brown. Insoluble. Dil. H.SO,, . Becomes pale yellow. Unchanged. Sodium hydrate. Unchanged. K eddish-yellow solution of sodium salt. Ammonia, Unchanged. Reddish-yellow solution of am- monium salt. Tannin reagent. Unchanged. Unchanged. Alum, Unchanged. Unchanged. Potassium bichro- mate, Unchanged. Unchanged. Stannous chloride, . Is not decolorised. On boiling, becomes dirty yellow ; on standing, decolorised. Zinc dust and am- monia. Reduced ; in the liltrate yellow colour returns. Quickly decolorised ; filtrate dirty red. Zinc dust and acetic acid, Reduced with difficulty ; filtrate and filter • i)aper become coloured orange-red. Quickly decolorised ; filtrate olive, edges of filter-paper blue. ' See Night blue tilration (p. 308). THE ANALYSIS OF DYESTUFFS. 3^ The Nitroso-dyestuffs. Colouring matter, .... Mesorcin green, Solid green 0. 11 NOH Description, Drab-coloured stiff paste (50 per cent.). , Water, Soluble on boiling ; brown solution. ^ Alcohol, ..... Solulile ; yellowish solution. 1 Ether, Insoluble. "^ '^ Benzene Insoluble. Heating on platinum foil, Burns away quickly and regularly, leaving no ash. Cone. H.^Oj, Dissolves with a deep brown colour ; on dilution with water, partial precipitation ; on heating, cone, solution gives oft' gas and becomes redder. Dil. KSOj, On heating, a clear pale yellow solution, not ex- tracted by ether. Sodium hydrate, .... Yellow solution, not extracted by ether. Ammonia Yellow solution. Tannin reagent, .... Alum, On heating, a pale yellow solution. Potassium bichromate, Dissolves on heating. Stannous chloride, .... White precipitate ; filtrate on heating colourless. Zinc dust and ammonia, . Easily reduced ; filtrate and edges of the filter-paper become violet-blue. Zinc dust and acetic acid, 314 SYNTHETIC DYESTUFFS. The Azo-dyestuffs. Monar.o. Colouring matter, . 1 Oriinge G. Ponceau 4GB. SOjNa 1 SOjNa 1 1 <:> 1 j 1 c> ^ Nn:NCoH5 1 SOsNa OH 1 OH Descriiition, . Yellow-scarlet powder. Yellow-scarlet powder. „ -Water, . Readily soluble ; orange. Fairly soluble ; orange. £> Alcohol, . Readily soluble ; orange. Fairly soluble ; orange. 3 Etlier, Insoluble. Soluble in traces. ^Benzene, . Insoluble. Soluble in traces. Heating on |ilatiuum foil, Chars and finally Imnis away, leaWng white ash. At first emits a white vapour, then burns with a luminous Hamc and \niffs up strongly ; finally chars and leaves white fusible residue. Cone H,SO„ . Dissolves with an orange colour ; on dilution, reddish-yellow ; on heating, cone, solution be- comes red. Dissolves with an orange colour ; on dilution, becomes reddish- yellow ; with only a little water, 1 a pale dirty red i>recipitat<: ; on heating, the cone, solution be- comes darker, then ruby-red, and finally black. Dil. H.SO,, . Unchanged. Unchanged. Sodium Iiydriite, Red solution. Solution becomes slightly redder. Ammoniii, Red-yellow solution. Solution becomes slightly redder. Tannin reagent, Unchanged. Unchanged. Alum, Unchanged. Unchanged. Potassium biehro- mate, Unchanged. Unchanged. Staniiou.s oliloride, . Orange ; decolorised on boiling. ong Orange-yellow precipitate ; on boil ing, decolorised fairly rapidly. Zinc dust and am- monia. Quickly reduced ; filtrate yellow. lure Rapidly decolorised ; filtrate i)ale greenish-yellow. Zinc dust and acetic acid. Somewhat quickly reduced ; filtrate colourless. Quickly reduced ; liltratc colour- less. THE ANALYSIS OF DYESTUFFS. 315 The Azo-dyestuWs—cmthiued. Mo n a::o — cunt in ueJ. Colouring matter, Description, j' Water, I ^ Alcohol, 1 "I j Ether, ^Benzene, Heating on platinum foil, Cone. HSOj. . Dil H2SO,, . Sodium hydrate. Ammonia, Tannin reagent, Alum, Potassium bicliro mate, Stannous chloride. Zinc dust and am monia, Zinc dust and acetic acid. Chrysoidine. I I Black crystals with metallic lustre. Very soluble. Very solulile. Soluble in traces ; pale yellow. Soluble in traces. Melts ; gives off a brown, aro- matic vapour, and then burns with a bright flame ; finally chars and leaves no ash. Dissolves with evolution of HCl, solution yellow ; on dilution, becomes orange ; cone, solution, on heating, be- comes dark olive. Unchanged. Orange-yellow precipitate ; ex- tracted by ether. Partial orange-3-ellowprecipitate ; soluble in excess, extracted by ether. Partial orange-brown precijiitate ; soluble on heating. Quantitative brick-red precipi- tate ; on heating, becomes dark brown and resinous. In the cold, unchanged ; on heating, turbid brown-yellow. Rapidly decolorised ; filtrate and edge of the filter-paper yel- lowish. Rapidly decolorised ; filtrate almost colourless. Orange II. <^ ^-N:lf-<^^S03Na OH Yellow-scarlet powder. Readily soluble ; orange. Readily soluble ; orange. Insoluble. Insoluble. Burns with luminous flame ; pufls up to form a voluminous black mass, which finally burns away, leaving white ash. Dissolves with a ruby-red colour ; on dilution, orange-yellow ; on heating, cone, solution becomes more yellowish, finally brownish- black. Unchanged. Solution becomes redder ; remains clear. Solution somewhat redder ; re- mains clear. In the cold, partial precipitation, orange-red ; on heating, re- dissolves. Unchanged. Orange-yellow precipitate ; on boiling rapidly, decolorised. Rapidly decolorised ; filtrate pale yellow. Quickly decolorised ; filtrate and edges of the filter-paper pale pink. ;i6 SYNTH KTIC DYESTDFFS. The Azo-dyestu^s - colli imied. Monazo — continutd. Colouring matter, . Chromolropc 2R. Chromolrope lOB. ;^;^H:KCA ;^^/H:N.C,^(.) SOjnJ ,' W^» ^^^^KJ^-^^ Description, . Brown-red powder. Brown powder. ^ /Water, . Red solution. Magenta-red solution. >> Alcohol, . Red solution. Magenta-red solution. 3 Ether, Insoluble. Insoluble. ^Benzene, . Insoluble. Insoluble. Heating on platinum foil, Glows without emitting vapour, leaving white ash. Glows and emits vapour ; melts I>artially, leaving a little fused ash. Cone. HSOj, . I Ussolves Avith effervescence, solution magenta-red ; on dilution, red ; on heating, cone, solution brownish-red. Dissolves with effervescence, solu- tion blue : on dilution, violet ; on heating, cone, solution brown- red. Dil. ELSO,, . Unchanged. Unchanged. Sodium hydrate, Unchanged. Unchanged. Ammonia, Unchanged. Unchanged. Tannin reagent, Unchanged. Unchanged. Alum, Unchanged. In the cold, complete precipitation, dark violet ; on boiling, de- colorised. Potassium bichromate, Somewhat darker. ... Stannous chloride, . In the cold, partial precipitation, rose-jiink ; on boiling, de- colorised. Unchanged. Zinc dust and am- monia. Decolorised ; filtrate becomes yellow. Decolorised ; filtrate becomes reddish-yellow. Zinc dust and acetic acid, Decolorised ; filtrate colourless. Decolorised ; filtrate colourless. THE ANALYSIS OF DYESTUFFS. i^7 The AzO-dyeStuflfs — continued. Monazo — continued. Colouring matter, . Azarinc S.^ Fast red D — Ainaranth. SOsNa o ? <.>r-<-> o I. =»>»■■• oU n SOgNa OH Description, . Brown-yellow paste. Dark brown powder. c • Water, Fairly soluble ; yellow. Readily soluble >> Alcohol, . Readily soluble ; yellow. Sparingly soluble. 3 Ether, Somewhat soluble ; yellow. Insoluble. m ■Benzene, . Insoluble. Insoluble. Heating on platinum foil, After the evaporation of the water, the residue emits a quantity of reddish vapour, ignites, chars, and finally burns away, leaving no ash. Very soon ceases to glow and melts, forming a yellowish-red ' glowing mass, eventually leaving a white ash, which is readily fusible. Ci.nc. ILSOj, Dissolves with evolution of SOj, solution deep violet-red ; on dilution, quantitatively pre- cipitated, brown-red ; on heat- ing, cone, solution becomes dirty brown. Dissolves, fonning blue - violet solution ; on dilution with water, bluish-red solution ; on heating, the cone, solution becomes violet brown. Dil. HoSOj, . In the cold, partial precipitation ; on heating, clear solution, ex- tracted with ether, yellow. Unchanged. Sodium hydrate, Violet precipitate, pale red filtrate ; extracted with ether, blue, the aqueous solution being a dirty reddish colour. Dark red solution. Ammonia, Same as with sodium hydrate. Darker solution. Tannin reagent. Unchanged. j Alum, On heating, yellow solution. Unchanged. 1 Piitassiumbichromate, On heating, brown turbidity. Unchanged. ^ Stannous chloride, . 1 Zinc dust and am- monia. On heating, partial precipitation ; yellow. Easily reduced ; filtrate becomes pale yellow. Quickly reduced ; filtrate pale greenish-yellow. Zinc dust and acetic acid. Reduced with some difficulty ; filtrate pale pink. Formed by the action of ammonium bisulphite on the azo-compound. 3>8 SYNTHETIC DYESTUFFS. The Azo-dyestuffs— --wj/inu^rf. Monazo — continued. Colouring matter, . Double brilliant scnrlH — Scarlet for sill: Mordant ijcllotr 0. 1 sojtJ I ' ' 'oh 1 OH COOK Description, . Brick-red powder. Red-yellow jiowder. _ -Water, . Readily soluble. Soluble in water ; yellow. • S> Alcohol, . Soluble. Not readily soluble. 1 ] Ether, . Soluble in slight traces. Soluble in traces. ^ ■ Benzene, . Soluble in slight traces. Insoluble. Heating on platinum foil, 1 Pulfs up, burns, chars, and finally leaves a fusible white ash. Putfs up strongly and then nielta, leaving a little ash. Cone. H.J50j, . Dissolves, solution magenta-red : on dilution, a red - brown precipitate; on heating, cone, solution becomes dirty violet- red. Brick reale red- dish-yellow solution. Sodium liydrate, Unchanged. Orange liquid. Ammonia, Unchanged. Orange liquid. Tauuin reagent. Unchanged. Acquires a darker colour. Alum, In the cold, a yellowish-red flocculent precipitate, which, on heating, redissolves. Unchanged. Potassium bichro- mate, Unchanged. Unchanged. Stannous chloride, . Yellowisli-red precipitate ; on long boiling, decolorised. Completely precipitated : yellow. Zinc dust and am- monia, Quickly reduced ; filtrate pale yellow. In the cold, not decolorised. Zinc dust and acetic acid, Somewhat quickly reduced ; filtrate colourless. Completely decolorised on boiling. THE ANALYSIS OF DYESTUFFS. 319 Disazo-dyestuffs. Colouring matter, Description, _ 1^ Water, £• Alcohol, -§ I Ether, -Benzene, Heating on platinum foil, Cone. HjSOj, DU. HJSOj, . Sodium hydrate, Ammonia, Tannin reagent, Alum, Potassium bichro- mate, Stannous chloride, . SOjNa I I SOjNa OH CH3 Dark greenish-brown powder. Readily soluble. Sparingly soluble. Insoluble. Insoluble. Emits a large quantitj' of j'ellow vapour, burns with a strongly luminous Harae, chars, and finally leaves fused white ash. Dissolves, fonning dark - blue solution ; on dilution, bluish- red ; on heating, cone, solu- tion becomes yellowish-brown. Unchanged. Partial precipitation, bluish- red ; on heating, redissolves. Same as with sodium hydrate. Unchanged. Partial precipitation, bluish-red; on heating, partly soluble. In the cold, quantitative pre- cipitation, carmine-red ; on heating, becomes hard. Dirty bluish-red ; decolorised on long standing. Bicbrich scarlet. Zinc dust and am- Quickly reduced ; filtrate and monia, I edgesof the filter- paper yellow. Zinc dust and acetic Reduced with some difficulty ; acid, I filtrate colourless. SOjNa OH Brick-red powder. Turbid solution. Fairly soluble. Soluble in tiaces. Soluble in traces. Becomes darker, then puffs up strongly, forming grey mass, which finally leaves a white fusible ash. Dissolves with a Malachite gi'een colour ; on dilution, becomes blue, then violet, and finally red ; on heating, the cone, solu- tion becomes blue, then dirty blue, and finally yellowish- brown. Unchanged. Becomes darker red-violet ; partial precipitation, rusty-brown ; fil- trate red-\iolet. Solution becomes darker. Unchanged. In the cold, a yellowish-red floccu- lent precipitate, which, on heating, partly dissolves. In the cold, partial precipitation, yellowish-red ; on heating, redissolves. Yellowish -red precipitate ; on boiling, red ; decolorised on long boiling. Quickly reduced ; filtrate pure yellow. Somewhat rapidly filtrate pale pink. reduced ; 320 SYNTHETIC DYESTUFFS. Disazo-dyeStufFs — rimlinued. Colouring matter, .... lirillinnt croceint. OH 1 0"'<:>-<3 SO.Na BOjITa Desciiption, Brick-red powder. ^ -Water, Readily soluble. ^ Alculiol Fairly soluble. 1 Etlier, Insoluble. ^Benzene, Insoluble. Heating on ]ilatinuiii foil, I'ufls up and quickly burns away, leaving small quantity of fusible white ash. Cone. H._SOj, .... Dissolves, forming red-violet solution ; on dilution with water, ]iartly precipitated, black ; liltratc pale red ; on heating, cone, solution becomes blackish-brown. Dil. H,SO, Unchanged. Sodium hydrate Dark dirty red solution. Ammonia Dark dirty red solution. Tannin reagent, . . ' . Unchanged. Alum Unchanged. Potassium bicluoniate. Unchanged. Stannous chloride, .... In the cold, partially inccipitati'd ; on heating, decolorised. Zinc dust and aninionia. . Rajiidly decolorised ; liltrate jiurc yellow. Zinc dust and acetic acid, Rapidly decolorised ; filtrate colourless. THE ANALYSIS OF DYESTUFFS. 321 Dyestuffs from Tetrazo-salts. Colouring matter, . Congo red. Bnizopurpurine B. SOgNa SO.^a NHo NE2 SOjNa NHj s'o.Na Desciiption, . Red-brown powder. Red-brown powder. ^ (-Water, . Readily soluble. Readily soluble ; yellowish-red. b' Alcohol, . Sparingly soluble. Sparingly soluble. 3 Ether, Insoluble. Insoluble. >■ Benzene, . Insoluble. Insoluble. Heating on platinum foil. Burns slowly, chars, and finally leaves u fusible ash. Burns slowly, chars, and finally leaves a white fusible ash. Cone. H..SO4, Dissolves, forming bhie solution ; un dilution, blue precipitate. Dissolves, forming blue solution ; diluted, dark brown flocculent precipitate. Dii. ajso^, . Blue precipitate. Brown precipitate. Sodium hydrate. Reddish - brown precipitate, soluble in water. Unchanged. Ammonia, The same as sodium hydrate. Unchanged. Tannin reagent. Unchanged. Unchanged. Alum, Unchanged. Unchanged. Potassium bichro- mate, Unchanged. Unchanged. Stannous chloride. Slowly decolorised. Decolorised on boiling. Zinc dust and am- monia. Readily reduced ; filtrate colour less. Readily reduced ; filtrate colourless. Zinc dust and acetic acid, Readily reduced ; filtrate colour- less. Readily reduced ; filtrate colourless 322 SYNTHETIC DYESTUFFS. Dyestuffs from Tetrazo-salts— «w/tntt«f. Coluuring matter. Descriptioii, . _ Water, _^ I Alcohol, . ;= I Ether, ^Beuzene, . Heating on platinum foil. Cone. M£Ot, Dil. HJSOj, . Sodium hydrate, Ammonia, Tannin reagent, Alum, Totassium bichro- mate, Stannous chloride, . Zinc dust and am- monia. Zinc dust and acetic acid, Bismarck- brnirn. I ' NH., Dark brown powder. Readily soluble. Readily soluble. Insoluble. Insoluble. Gives off white vajwur, chars and burns away, leaving no ash. Dissolves, with evolution ofHCl, to dark bruwn solution ; on dilution, dark yellow-brown with partial precipitation ; cone, solution, on heating, be- comes black-olive. In the cold, partial dark precipi- tate ; dissolves to reddish- yellow solution on warming. Partial yellow-brown precipitate, extracted with ether. Same as with sodium hydrate. Partial red-brown precipitate ; dissolves on heating. Partial brown precipitate ; dis- solves on heating. Quantitative dark orange-brown I precipitate ; on heating, be- comes black. Partial orange-brown precipi- tate ; on heating, rapidly decolorised. I Rapidly decolorised ; filtrate and edge of filtor-paper I slightly orange. Rapidly decolorised ; filtrate a dirty reddish colour. Diamine blaek RO. /\/\ lO.'^VV^ «V»\/\/' BUck powder. Violet-black solution. Sparingly soluble. Insoluble. Insoluble. Burns with luminous flame, chars and leaves white fusible residue. Dissolves, forming blue solution ; on dilution, reddish-blue pre- cipitate. Reddish-blue precipitate. Violet solution. Violet solution. Unchanged. Unchanged. Unchanged. Decolorised on boiling. Rapidly reduced ; filtrate becomes blue on exjwsure to the air. Readily reduced ; filtrate becomes blue on exposure to the air. THE ANALYSIS OF DYESTUFFS. 323 Di- and Tpiphenylmethane Dyestuffs. Bade. Colouring matter, Description, . _ /■Water, ■§■ Alcohol, . 3 I Ether, ^Benzene, . Heating ou platinum foil, Cone. ttSOj, . DO. H^SOj, . Sodium hj'drate, Ammonia, Tannin reagent, Alum, Potassium bichro mate, Stannous chloride, . Zinc dust and am- monia, Zinc dust and acetic acid, / ./ ■NCCHs)., ■ = N(CH3)2C1 Yellow powder. Very soluble ; yellow. Very soluble ; yellow. Insoluble. Insoluble. Becomes red-orange, yellow vapour is given off, finally chars and burns away, leaving no ash. Dissolves, with evolution of HCl, to colourless solution ; on dilution, becomes yellow ; cone, solution, on heating, be- comes brown-yellow. Unchanged ; decolorised on boiling. White precipitate ; extracted on shaking by ether. Same as with sodium hydrate. Almost completely precipitated, yellow ; becomes brown and resinous on boiling. Unchanged. Quantitative yellow precipitate, which becomes resinous on heating. Filtrate colourless ; colour does not reappear ; on standing, precipitate on filter becomes yellowish. Becomes blue on reduction. Brilliant green. ^(^ ys{z^^)„ C6H5.0 ) = N(CoH3)„Cl Green crystalline plates with metallic lustre. Readily soluble. Readily soluble. Soluble in ti'aces. Soluble in traces. Melts and burns with a smoky flame ; the carbon burns away, leaving a little asli. Dissolves, giving dark yellow solu- tion ; diluted, brownish-yellow ; on heating, cone, solution be- comes darker. Red-brown solution. Dirty pale gi'een precipitate, quanti- tative ; on heating, colourless ; extracted by ether. The solution becomes milk-white turbid ; extracted by ether. In the cold, almost quantitative precipitate ; on heating, some- what soluble. Unchanged. Almost quantitative dark green precipitate ; on heating, partly soluble ; the liquid becomes covered with a coppery iridescent film. In the cold, quantitative green pre- cipitate ; on heating, mostly dis- solved ; filtrate dark green. Filtrate colourless. Reduced with great difficulty filtrate colourless. 324 SYNTHETIC DYESTUFFS. Di- and Triphenylmethane Dyestuffs— 'on/iHt/erf. Basic — coiitiii ued. Colouring matter, Description, . g .Water, . .§> I Alcohol, , 3 I Ether, oc 1 ^Benzene, . Heating on platinum foil, Cone. aSOj, . Dil. HSOj, . Sodium liydratf, Ammonia, Tannin reagent, Alum, Potassium bichro- mate. Stannous chloride, . Zinc dust and am- monia, Zinc dust and acetic acid, Magenta — mostly / NHo ^<^ y = TSKM Dark green crystals, metallic lustre. Readily soluble ; purple-red. Readily soluble. Soluble in traces ; crystals be- come blue. Insoluble ; crystals become blue. Gives off red vapour, then melts and burns with a smoky (lame, leaves no ash. Dissolves with evolution of HCl, solution dark brown- yellow ; diluted with water, becomes yellowish -red, then yellow, and finallj' almost colourless ; cone, solution, on heating, becomes dark olive- brown. .Solution first yellowish - red, then yellow, finally almost colourless ; ou heating, red colour returns. Quantitative red -brown pre- cipitate, extracted by ether. With excess, colourless solu- tion ; a slight addition causes turbidity. In the cold, almost quantitative precipitate ; on heating, it becomes resinous and partially dissolves. In the cold, partial red pre- cipitate ; dissolves on heating. ljuantitati\e red - brown pre- ci]iitate ; on heating, becomes resinous. In the cold, i)artial precipita- tion ; on heating, dissolves with separation of basic stannous chloride. Methyl violet B. = BH(0H,)201 Olive-green crystalline powder. Readily soluble ; violet Readily soluble ; violet. Soluble in traces. In the cold, not very soluble ; on heating, moderately soluble. Emits w-liite vapour, melts and ignites, leaving no ash. Dissolves with evolution of HCl, solution orange : diluted with water, orange-brown, brown- olive, olive-green, blue-green ; on heating, cone, solution be- comes brown. Deep red - bi-own standing, green. Quantitative violet-brown pre- cipitate, extracted by ether. Uecomcs paler and redder ; quan- titative dirty pale gi-eyisli-red precipitate, extracted by ether. Quantitative violet precipitate ; on heating, filtrate becomes slightly red. Unchanged. Filtrate colourless ; filter-paper red. Reduced with some difficulty filtrate colourless ; on boilinj pale pink. Quantitative black-violet precipi- tate ; mostly soluble on heating, partly resinous. .\lmost quantitative violet pre- cipitate ; on heating, inaigo blue, partly soluble ; filtrate azure-blue with green fluor- escence. edge of I Filtrate colourless. Reduced with some difficulty ; filtrate colourless; the violet colour very slowly restored. THE ANALYSIS OF DYESTUFFS. 325 Di- and Triphenylmethane T>yestuSs—co7iHnued. Basic — cont iiuied. Colouring matter, Description, . Water, . 'S- Alcohol, . 02 Ether, ^ Benzene, . He f iting on platinum oil. Cor c. H.,SOj, . Dil. HJSO^, . Sodium hydrate. Ammonia, Tannin reagent. Alum, Potassium bichn mate. Stannous chloride. Zinc dust and am- monia, Zinc dust and acetic acid. Crystal violet. 0^( CH3)„ W(CH3)„ N(CH3)„C1 Yellow - green crystals with Green powder with metallic lustre. metallic lustre. Readily soluble ; violet. JIagenta-red solution. Readily soluble. Almost insoluble. Somewhat soluble ; the crystals become blue. The crystals melt and burn with a smoky flame, then char, and finally burn away, leav- ing no ash. Dissolves with evolution of SGI, solution orange-yellow : diluted with water, olive- green, yellow-gi-een, yellow ; on heating, cone, solution becomes dark brown. Olive-green solution ; on heat- ing, emerald green. Blue-violet quantitative precipi- tate, extracted by ether. The solution becomes milky, eventually milky-white. In the cold, and on heating, quantitative precipitate. Unchanged. Quantitative violet-black pre- cipitate with metallic lustre ; on heating, partly soluble (resinous). In the cold, quantitative violet precipitate ; on heating, partly soluble. Filtrate colourless ; edges of filter-paper lilac. Reduced with dilBculty ; filtrate becomes pale blue ; edges of the filter-paper pale blue- violet. Magenta-red solution. Soluble in traces. Insoluble. Chars and leaves no ash. Orange-yellow solution, evolution of HCl ; diluted, yellow ; heated, brown-olive ; on standing, red- brown flocculent precipitate. Cold, solution yellow-bi'own ; hot, ruby-red. Cold, complete precipitation ; red hot, yellow-brown jirecipitate ; filtrate colourless. Solution pale yellowish-red. Completely precipitated, brown- red. Cold, slight brown-red turbidity ; hot, clear magenta-red solution. Cold, completely precipitated, brown-red ; hot, almost clear orange-red. Cold, partial violet-red precipita- tion, soluble on boUing. Rapidly decolorised on boiling ; filtrate colourless. Easily reduced ; filtrate colour- 326 SYNTHETIC PYKSTUFFS. Di- and Triphenylmethane Dyestuflfs— co/jlatiuiui foil, Cnnc. HJSO^, . Dil. H,_SO„ . Scidium hydrate, i Ammonia, Tannin reagent, Alum, Potassiumbichromate, Stannous chloride, . Zinc dust and am- monia, Zinc dust and acetic acid, Acid green. / Nll(0jH5)0H,. Aeid magenta — mostly \ CgH^SO^Na SOjNa Uai k green jiowder. Readily soluble ; green. Slightly soluble. Insoluble. Insoluble. Burns away and leaves wliiti fusible ash. Dissolves, forming dark orange solution ; on dilution, becomes olive, then green ; on heating, cone, solution becomes dark olive-brown. On standing, colour becomes paler. Becomes colourless. Becomes colourless. Unchanged. Unchanged. Unchanged. Unchanged. Readily reduced ; filtrate colour- less ; on addition of acetic acid, becomes green. Reduced with dilHeulty ; liltrate pale green. lira, Olive. CHa Readily soluble ; magenta-red. Readily soluble. Insoluble. Insoluble. (Jakes together, burns away, and linally leaves a white fused ash. Dissolves, forming dark orange solution; diluted, carmine-red ; on heating, cone, solution becomes olive-brown. Unchanged. Colourless solution. Colourless solution. Unchanged. Unchanged. Unchanged. Unchanged. Filtrate colourless ; on addition of acetic acid, colour returns. Reduced with difficulty ; filtrate pink. THE ANALYSIS OF DYESTUFFS. Di- and Triphenylmethane DyestuWs—continued. Acid — continued. Colourinf; matter, Description, ^ Water, S? Alcohol, I j Ether, Heating on platinum foil, Cone. HjSOj, Dil. H._504, . Sodium hydrate. Ammonia, Tannin reagent, Potassium bichro- mate. Stannous chloride, Zinc dnst and am- monia. Zinc dust and acetic acid, Add violet N. Alcohol, . Readily soluble. Somewhat readily soluble. 1 Ether, Insoluble. Soluble in traces. " '■Benzene, . Insoluble. Insoluble. Heating on platinum foil, Emits white vapour of an aro- matic odour ; chars and burns away, leaving white ash. Melts, puffs u]i, chars, and then burns away, leaving only a little white ash. Cone. H..JSO4, . Dissolves, forming dark brown- red solution : on dilution, blue ; on heating, cone, solu- tion becomes blackish-brown. Dissolves, forming red-brown solu- tion •, on dilution, blue precipi- tate ; filtrate colourless ; on heating, cone, solution violet- black. Dil. H._,SO„ . Unclianged. On heating, quantitative blue pre- cipitate, not extracted by ether. Sodivim liydratp, Dark red solution. On heating, becomes dark iiurple ; on continued boiling, pale red. Ammonia, Dark red sohition. Same as with sodium liydrate. Tannin reagent. Unchangi'd. On heating, partial preiijiitation. Alum, . Potassium bichro- mate. Unchanged. Unclianged. Partial precipitation ; on heating, seiiarates more completely. Unchanged. Stannous cldoride, . In the cold, mostly precipitated ; on heating, partly soluble. On heating, quantitatively precipi- tated, blue. Zinc dust and am- monia, Reduced ; liltrate colourless ; on addition of acetic acid, violet colour. Somewliat quickly decolorised ; liltrate pale blue. Zinc dust and acetic acid. Reduced with groat dilliculty, requires boiling ; liltrate ]iale Reduced witli dilliculty : in the liltrate the blue eciloiir returns. green. * The corresponding homo-derivative will always be present (see p. 84). THE ANALYSIS OF DYESTUFFS. 329 Pyronine DyestuflFs. Colouring matter, Description, .Water, •9 I ^ Alcohol, 3 1 Ether, '■Benzene, Heating on platinum foil, Cone. KSOj, . Dil. H.jSOj, . Sodium hydrate. Ammonia, Tannin reagent. Alum, Potassium bichro- mate, Stannous chloride, . Zinc dust and am- monia. Zinc dust and acetic acid, Fast add violet B. r, iCOONa Red-violet powder. Dark rose-red solution. Pink solution. Insoluble. Soluble in traces. Emits a violet, then a brown vapour ; melts and burns away, leaving a fusible white ash. Orange-red solution ; on dilu- tion, red-violet ; on standing, partial precipitation, bluish- red. Partial precipitation, violet-red ; on heating, more soluble. Somewhat redder. Somewhat redder. Unchanged. Partial precipitation, bluish-red. Clear solution ; on heating, some- what paler. In the cold, almost completely precipitated, bluish-red ; on heating, somewhat soluble. Decolorised on standing. Reduced on boiling ; filtrate at once becomes pink. Fast ackl blue R. (OCA) Dark blue powder. Blue- violet solution. Blue-violet solution. Insoluble. Insoluble. Chars and leaves a quantity of grey Brown-red solution ; on dilution, completely precipitated, dark blue. In the cold, completely precipi- tated, dark blue ; on heating, slightly soluble, violet. Solution in the cold, violet ; on heating, red-violet. Solution violet. Unchanged. Partial precipitation ; on heating, dark blue ; filtrate violet-red. Dirty olive-gi'een solution. Almost completely precipitated, dark blue ; filtrate in the cold bluish ; on heating, pale violet. Easily reduced ; filtrate faint yellowish-red ; on addition of acetic acid, pale violet. 330 SYNTHETIC DYESTUFFS. Pyronine Dyestuffs— co»rf«n«erf. Colouring matter, . Uranine. Description, . /-Water, S j Alcohol, . •I Ether, V Benzene, . Heating on platinum foil. Cone. HjSOj, . Dil. H.,SO,, Sodium hydrate, Amraniiia, Tannin reagent, Alum, Potassium bichro- mate, Stannous chloride. Zinc dust and am- monia. Zinc dust and acetic acid. j^^jOOOKa \/ Brown crystals with green metallic lustre. Readily soluble ; yellow with strong yellow-green fluor- escence. Readily sol uble ; orange with yellow-green fluorescence. Insoluble. Insoluble. Swells up very strongly, melts, and then burns away, leaving fusible ash. Dissolves, giving a yellow solu- tion with green fluorescence ; on dilution, yellow ; the cone, solution, on heating, becomes dark brown-red. Fluorescence disappears almost entirely. Unchanged. Unchanged. Fluorescence disapjiears. In the cold, partial precipitation, orange-yellow ; on heating, yellow solution. Fluorescence disappears. In the cold, and also on heating, partial precipitation, orange- yellow. Quickly reduced ; in the tiltrate the colour returns. Quickly reduced ; filtrate colour- less. .-'^lOOOH. \/ Crystals with reddish metallic lustre. Very readily soluble ; red with yellow fluorescence. Soluble ; very strongly fluorescent. Insoluble. Insoluble. Burns away slowly and gradually, and leaves a white fusible ash. Dissolves, giving a yellow solution ; on dilution, quantitatively pre- cipitated, orange-red ; the cone. solution, on heating, becomes dark red. In the cold, and on heating, quantitative orange-red pre- cipitate, extracted by ether. Unchanged. Unchanged. Fluorescence disappears. Partial precipitation, orange-red. Unchanged. In the cold, quantitative bright red precipitate ; on heating. De- comes deeper carmine-red. Quirkly reduced ; filtrate bright pink with strong green fluor- escence. Somewhat quickly filtrate reddish reduced ; with slight THE AXALYSIS OF nYESTFFFS 331 Pyronine Dyestuffs — cwiUnued. Colouring matter, . ^^ Description, Water, Alcohol, 3 I Ether, ^Benzene, Heating on platinum foil, Cone. aSOj. . Dil. H,SO^, . Sodium hj'drate, Ammonia, Tannin reagent, Alum, Potassium bichro- mate, Stannous chloride, . Zinc dust and am- monia. Zinc dust and acetic acid. Eosine scarlet BB extra. Eosine BN. Readily soluble ; red with slight green fluorescence. Readily soluble ; cannine - red with yellow fluorescence. Soluble in traces. Soluble in traces. Explodes slightly, then chars and bums away with diffi- culty, leaving white fusible ash. Dissolves with yellow colour ; diluted, quantitative orange precipitate ; on heating, cone. solution becomes dark brovi-n red. Quantitative orange precipitate, extracted by ether. Unchanged. Unchanged. Fluorescence disappears. In the cold, jrartiaUy precipi- tated ; on heating, pale orange. Fluorescence disajipeai's. In the cold, pale orange-red quantitative precipitate ; on heating, pale red, somewhat soluble. Quickly reduced ; filtrate and edges of the filter-paper car- mine red. Reduced with great difficulty, even on boiling ; filtrate orange-yellow (acetic acid pre- cipitates the insoluble acid). Brythrosine. -,ONa Readily soluble ; very slight yellow- brown fluorescence. Readily soluble with slight green- yellow fluorescence. Soluble in traces. Soluble in traces. Emits iodine vapour, then chars, I and finally leaves a fusible white | residue. | Dissolves, givin" dark yellow solu- 1 tion ; on dilution, quantitative 1 orange-red precipitate ; the cone, solution, on heating, becomes ' dark red-brown and much iodine is given off. Quantitative scarlet precipitate, extiacted by ether. Unchanged. Unchanged. Unchanged. In the cold, quantitative bright red precipitate ; on heating, scarlet ; filtrate yellow. Unchanged. Quantitative red precipitate. Quickly reduced ; filtrate pale pink with strong green fluores cence ; edges of the filter-paper yellow. Reduced with great difficulty ; filtrate yellowish with yellow - green fluorescence. 332 SYNTHETIC PYESTUFFS. Pyronine HyestuiTs— continued. Colouring matter, Description, ^ Water, i? Alcohol, 3 I Ether, ''Benzene, Heating on i)latinum foil, Cone ttSO,, . Dil. H.SO,, . Sodium liydrate, Ammonia, Tannin reagent, Alum, Potassium bichro- mate. Stannous chloridi', Zinc dust and am monia. Zinc dust and acetic acid. . Br Br \/\/V\0K. 00 CO OH -COX CO Description, . Brownish-yellow paste. Yellow paste. ^ , Water, . 5" Alcohol, . Almost insoluble (even on boil- ing)- Readily soluble ; deep yellow. Slightly soluble ; brownish-red. Red-brown solution. 1 Ether, . Fairly soluble ; yellow. Fairly soluble ; yellow-green. "^ ''Benzene, . Fairly soluble. Fairly soluble ; yellow -green. Heating on platinum foil, After evaimrating the water, the Alizarine at first sublimes, then chars and burns away, lea\-ing no ash. Brownish - yellow dried powder, melts to a black liquid, sublimes, ignites, and finally burns away, leaving no ash. Cone. H.,S04, . Dark yellowish-red solution ; on dilution, yellow precipitate. Brown -red solution ; on dilution, almost completely precipitated. Dil. KSO,. . Unchanged. Unchanged. Sodium hydrate, Violet solution. Dark brown-red solution. Ammonia, Red-violet solution. Dark brown-red solution. Tannin reagent. Alum, . On heating, partly dissolves to form orange solution. In the cold, unchanged ; on heat- ing, an orange-red precipitate. Potassium bichro - mate. On boiling, an orange-brown precipitate. Unchanged. Stannous chloride, . Unchanged. In the cold, unchanged ; on boil- ing, brown precipitate. Zinc dust and am- monia, With zinc powder, orange-red ; on filtering and warming the filtrate original colour restored. Reduced on boiling ; yellowish - green ; filtrate rapidly becomes dark brown. Zinc dust and acetic acid, THE ANALYSIS OF DYESTUFFS. 335 Oxyketone ByestuSs—coiitinued. Colouring matter, Description, r Water, ^ Alcohol, I j Ether, ^Benzene, Heating on platinun: foil, Cone. HoSOj, . Dil. SSO,. . Sodium hydrate, Ammonia, Tannin reagent. Alum, Potassium bichromate, Stannous chloride, . Zinc dust and am- monia. Zinc dust and acetic acid. Alizarine blue. rYY^ I I \/ Greyish-blue paste. Insoluble. Soluble ; greyish -blue solution. Fairly soluble ; reddish. Fairly soluble ; red. After the evaporation of the water, a reddish vapour is emitted, the mass then chars and burns away, leaving no ash. Dissolves, forming violet - red solution ; on dilution, pale red ; on heating, cone, solution becomes dark brown. In the cold, dirty brown pre- cipitate ; filtrate pale red. Forms blue solution ; with excess of alkali, green. Forms greenish-blue solution. Blue-black ]>recipitate on heating. Blackish precipitate. Blackish i)recipitate. Reduces to red solution ; filtrate reoxidised to blue on exposure to the air. Alizarine green S. CO OH \/ Reddish brown paste. Red-violet solution. Violet-red solution. Soluble in traces. Soluble in traces. Carbonises quickly, leaving greyish -white ash. Ruby-red solution ; brown precipi- tate on dilution ; on heating, becomes darker. In the cold, unchanged ; on heat- ing, a greenish-grey precipitate. Ruby-red solution. Ruby-red solution. Slight grey precipitate. Violet solution. Red-brown solution. In the cold, dirty violet turbidity ; on heating, completely precipi- tated, grejish-green. Reduced on boiling, brownish filtrate at once becomes dark red-brown. 32(> SYNTHETIC DYESTUFFS. Oxyketone Dyestuflfs — continued. Colouring matter, Ji: Description, Water, Alcohol, a j Ether, ^Benzene, Heating ou platinum foil, Cone. H.JS04. . Dil. H.SO^. . Sodium hydrate. Ammonia, Tanuiu reagent, Alum, Potassium bichro mate, Stannous chloride. Zinc dost and am monia, Zinc dust and acetic acid. Alizarine black P. CO OH 00 I N I I \X Greyish-black paste. Somewhat soluble ; olive. Somewhat soluble ; brownish. Slightly soluble; brownish-yellow, Soluble in traces. Dries, forming a black mass, which melts, eives a brown sublimate, and then burns away, leaving no ash. Dark brown solution ; on dilu- tion, yellow-brown precipi- tate ; filtrate orange. Brown residue ; filtrate, when cold, pale yellow. Grcyish-greeu solution. In the cold, brownish-black solution ; on boiling, reddish- black. Black precipitate. Black precipitate. Reddish-grey precipitate. Reduced on boiling ; filtrate brown-red, rapidly becoming darker. Acid aliiarine hlu< BB. OH CO OH , I I r )\/X/\/80,H. OH CO OH Red-brown powder. Soluble with a carmine-red colour. Slightly soluble ; red. Soluble in traces. Insoluble. Melts and burns away, leaving white ash. Dissolves, forming red-violet solu- tion ; on dilution, red. Red solution ; unchanged on boil- ing. Blue solution ; on standing, blue pi-ecipitate. Blue solution ; not precipitated on standing. On heating, a brick-red precipitate ; filtrate orange. Red-violet solution. Ou heating, dark brown solution. Completely precipitated, red-violet. At first a blue coloration ; then decolorised, giving a colourless filtrate. Reduced, forming a brick-red solu- tion. THE ANALYSIS OF DYESTUFFS. Oxazines and Thiazines. Colouring matter, Description, . _ , Water, §> I Alcohol, . 3 I Ether, "■Benzene, . Heating on platinum foi], Cone. H^SOj, Dil. H.JSO4, . Sodium hydrate, Ammonia, Tannin reagent. Alum, Potassium bichro- mate. Stannous chloride, . Zinc dust and am- monia. Meldola's blue. I I I I I I N (zinc chloride double salt). Violet, crystalline. Readily soluble. Sparingly soluble. Insoluble. Insoluble. Emits white vapour, burns with crepitation, chars, and finally burns away, leaving a quantity of infusible ash (zinc oxide). Dissolves, with evolution of HCl ; solution brown ; on dilution, blue. Unchanged. On heating, completely de- colorised ; brown precipitate. On heating, completely de- colorised ; brown precipitate. Blue precipitate. Unchanged. Unchanged. On heating, quantitative blue precipitate. Easily reduced ; filtrate colour- less ; on addition of acetic acid, colour restored. Zinc dust and acetic Quickly reduced ; filtrate colour- acid, less, slowly becoming blue. ,N(CH3).3C1 Small crystals with greenish metallic lustre. Readily soluble. ReadOy soluble. Insoluble. Insoluble, Emits a, greenish vapour, burns with a smoky flame, chare, and then burns away, leaving no ash. Dissolves with evolution of HCl ; solution grass-green ; diluted with water, blue. Unchanged. Violet-blue solution ; excess of strong caustic soda produces precipitate ; extracted by ether. Unchanged. Quantitative blue precipitate, somewhat soluble on boiling. Unchanged. Quantitative red - brown pre- cipitate ; on heating, olive- green, partly soluble. Quantitative dirty blue precipitate, becoming colourless on heating. Quickly reduced ; the filtrate and edges of the filter-paper rapidly become violet. Easily reduced ; filtrate and edges of the filter-paper rapidly become blue. 338 SYNTHETIC DYESTDFFS. Oxazines and Thiazines—continued. Colouring matter, Description, ^ , Water, .§> Alcohol, 3 I Ether, ^Benzene, Heating on platinum foil, Cone. HlSOj, . Dil. H.SO4, . Sodium hydrate, Ammonia, Tannin reagent. Alum, Potassium bichro- mate. Stannous chloride, . Zinc dust and am- monia. Zinc dust and acetic acid, Toluidine bhie 0. H (zinc chloride double salt). Dark olive-green powder. Blue solution. Blue-violet solution. Soluble in traces. Insoluble. Melts, swells up, emits much strongly smelling vajjour, and finally burns away, leaving a residue of zinc oxide. Green solution, HCl evolved ; on dilution, blue-green ; cone. solution, on lieating, violet- black ; dUuted, red-violet. Unchanged. In the cold, almost quantitative brown - violet precipitate ; mostly soluble on boiling. Slight dark violet precipitate ; filtrate violet. In the cold, almost quantitative dark blue precipitate, sliglitly soluble on lieating. Unclianged. In the cold, complete precipita- tion, dark brown ; on heating, almost clear green solution. In the cold, almost complete jiroeipitation, pale blue ; on boiling, decolorised. Easily reduced, colourless ; filtrate at once becomes red- violet. Ea.sily reduced, cohmrless ; fil- trate at once becomes pale blue. Slelhylene green. (0H3)Jf^ ,^ /\/\^(0Hj)201 I I I J (zinc chloride double salt). Dark brown powder. Readily soluble ; blue-green. Readily soluble. Insoluble. Insoluble. Emits a little greeuisli vapour and swells up, then burns away, leaving residue of ZnO. Dissolves with evolution of HCl ; solution bluish-green ; diluted, greenish-blue ; on heating, cone, solution becomes black-Wolet. Unchanged. Almost quantitati\e violet pre- ci]iitate, extracted by ether. Partial precipitation, blue-black ; extracted with etlier. Quantitative blue-gi-een precipi- tate, dissolves on heating. Unchanged. Completely precipitated, brown- black. Quantitative dirty green precipi- tate, which, on filtering, quickly becomes [laler. Quickly reduced ; the filtrate and edges of the filter-paper rapidly become violet. Reduced with some ditliciJty, filtrate and edges of tlie filter- pai>er rapidly become blue. THE ANALYSIS OF UYESTUFFS. Safranines and Indulines. Colouring matter, . Heating on platinum foil, Cone. H.JSO4, Dil. H^SOj, . Sodium hydrate, Ammonia, Tannin reagent, Alum, Potassium bichro- mate, Sa/raniiic. OH3. I I I I CIH2N Brown powder. Readily soluble ; red solution. Readily soluble ; red with yellow fluorescence. Insoluble. Insoluble. A red vapour is given off ; the mass melts, ignites, chars, and finally burns away, leav- ing no ash. Dissolves with evolution of HCl, solution green ; diluted, becomes blue, violet, and finally red ; the cone, solution, on heating, becomes blaokish- olive. I Partial dirty orange - red pre- cipitate ; dissolves on heating. Partial red-brown precipitate, extracted by ether. No precipitate. Partial precipitation of the lake. Unchanged. Quantitative I'ed precipitate, more soluble on heating. Mcthyleiu: violet. /\^\y\ Cl(CH3).>N^ I I I N Brown powder. Soluble with wine-red colour. Soluble with wine-red colour. Soluble in traces. Insoluble. Puffs up strongly, emitting a violet vapour, chars, and finally burns, leaving no residue. Dissolves with evolution of HCl, gi'een solution ; on dilution, be- comes blue, then violet, and finally wine-red. Somewhat darker and bluer on Stannous chloride, . I Partial buff-coloured precipitate ; I dissolves on heating. Zinc dust and am- monia, Zinc dust and acetic acid, Easily reduced ; the colour is restored immediately. Easily reduced ; the colour is restored immediately. In the cold, little change ; on heat- ing, colour base slowly separates. Unchanged. Partial red-violet precipitate. Unchanged. Brown precipitate, which redis- solves on boiling. Fine red-violet precipitate. Colour incompletely destroyed. Reduced to a bright yellow solu- tion ; partially restored on ex- posure to the air. 540 SYNTHKTIC DYESTUFFS Safranines and Indulines— continued. Colouring matter, Atine scarlet G. Description, . /•Water, ^Alcohol, . I j Etlicr, '^ Benzene, . Heating on iil.itinum foil. Cone. H-^Oj. . Dil. H,SO„ . Sodium hydrate, Ammonia, Tannin reagent, Alum, Potassium bichro mate, Cl CB^\^ Brown powder. Readily soluble, boiling ; red solution. Readily soluble ; the solution exhibits a strong fluorescence. Insoluble. Insoluble. Carbonises and leaves little ash. HCl evolved ; blue-green solu- tion ; on dilution, ]>artial red- brown precipitate. In the cold, red turbidity ; on boiling, original colour re- stored. Unchanged. Unchanged. Scarlet-red ]>reci|)itatc, dissolves on boiling. Unchanged. Brown precipitate, insoluble on boiling. Stannous chloride, . Complete precipitation, dirty red. Zinc dust ami .tm- monia, Zinc Just and acetic acid, Solution rapidly dreolorised ; filtrate colourless ; colour more or less restored on exiwsure to air. Solution quickly reduced ; on exposure to air the colour is more or less restored. Indulint (spirit soluble). .See jiagi- 145. brown-black powder. Sparingly soluble ; violet. Dark violet solution. Red solution. Red solution. Melts, swells uji, emits Wolet vapours, chars, and finally bams away, leaving no ash. Blue-Wolet solution ; diluted, violet ; on standing, jiartial violet precipitate. Unchanged. In the cold, completely pre- cii)itated, red ; on boiling, some- what soluble. The .lanie as with sodium hydrate. Completely precipitated, \-iolet. In the cold, ]>artial precipitation violet ; on heating, clear nolet solution. In the cold, completely pre cipitated, brown - violet ; the pri-oipitate almost entirely soluble on boiling. In the cold, almost completely precipitated, violet ; on heating, I>artly soluble. Decolorised ; filtrate at once be conies pink ; with acetic acid violet-red. Reduced, yellow ; filtrate remains yellow-brown. THE ANALYSIS OF DYESTrFFS. 34 1 The examination of unknown dyestuffs.— For the purpose of detecting the composition of an unknown dyestufF or a mixture of dj-estuti's, tlie method of Rota {Chem. Zeit., 1898, 437), which depends on the behaviour of dyestuffs when treated with a solution of SnCI, + HCl, is of value. ^Vhen the dyestuti' is treated with a dilute solution of this reagent (1 : 10,000) until the boiling-point is reached, only members of certain classes are reduced, these being derivatives of mono- and diimido-quinones, while those derived from a quinone containing one diatomic carbon group instead of an oxygen atom in the quinone ring are not reduced. Thus the reducible colours are derivatives, such as nitro-, nitroso-, azo-, and quinoneimide colours of = R = N- or -N = R = N- oximidoquinone diimidoquinone. Those not reducible are the following, such as the oxyquinone and tri- phenylraethane dyestufts : — = R = C= and -N = R^C = oxycarboquinone imidocarboquinone. If the solutions reduced by SnCL are examined, it is found that some of them, after adding a few drops of ferric chloride, or even by shaking the solution, previousl}- neutralised with KOH, in air, remain unchanged ; while others are oxidised to the original colour. The former are the nitro-, nitroso-, and azo-colours, which yield stable amines on reduction : the latter are the quinoneimide derivatives, yielding leuco-bases which are easily reoxidised. The unreducible colours can be divided into two groups according to whether they are derived from oxycarboquinone or imidocarboquinone. To the latter belong the Magentas, Acridines, etc., which, when warmed in aqueous solution with KOH, are decolorised or precipitated ; the former, bj' reason of their acid character, yield, witli alkalies, bright-coloured salts which are usually soluble. The dyestufls can be thus divided into four classes, to which two or three large groups witli similar chromophores belong. The further division of these dyestuffs into single families is founded on the different nature of the salt-yielding groups in them. The question whether the dyestuffs contain amido- or imido-groups, carbosyl or sulphonic groups, has then to be dealt with. For this purpose the use of ether and the different fibres (cotton, wool, etc.) is of great service. ITablh a. 34^ SYXTHKTir T>YE>*TrFPS. A. Classification of the Org-anic Dyestuffs. A jwrtioii of tlie aqueous or dilute alcoholic solution of tlu' dyestulf is treated with HCl and theu with SnClo. * It is completely decolorised : — lieducibU Di/esluffsA The decolorised sortion of the original solution is treated witli a 20 ])er cent, solution of EOH and wanned. The .solution is de- colorised, or a pre- cipitate is formed. Quinoneimido - dye- stuffs. Class III. Xu precipitate is formed, and the liquid becomes in- tensely coloured. Quinone dyestuffs. Class IV. * The aqueous or alcoholic solution should contain 1 part of dyestuif in 10,000 jiarls solvent, and 5 c.c. nf this mixed with 4-5 drops of concentratt'd hydrochloric acid and then with asimilar quantity of SnCLj (10 percent, solution prepared by dissolving tiiiin hydrochloric acid). The mixture should be shaken and, if necessary, heated to boiling. If decolorisation is only jiartial, more tin solution may be added, or the dye solution may be further diluted. t Certain indulines are only decolorised with difficulty, and do not give completely colour- less solutions. .\ftor having Sfi)arated the colours according to the foregoing table, tlieir identification is much sinipliticd b^- tlic help of tlie detailed properties and reactions of t3-pical dyestutts already given.' For the detection of bromine or iodine the solution of the dyestutl' is boiled with zinc dust and KOH, and tlie filtered solution, after being acidified with acetic acid, tested with chlorine water or starch solution. 'I'iie dye.stiitl' may also be ignited with CaO, the residue treated with nitric acid, and the halogen in the solution tested for in the usual way. To determine the presence of sulphur, in order, for instance, to distinguish between the thiazines and the oxazines, the subst-ancc is melted witli nitre and the melt tested for sulphuric acid. In case the colour can be reduced, the tin is removed by treatment with H.,S and the product examined. Thus the a/.o-compounds yield a mixture of at least two primary amines, according to the equation R N = N-R,-h2H.. = R-NH.,-fK, -NHj These can sometimes be easily separated by ether ; the reduced solution is treated with H.,S to remove tin, and the solution rendered alkaline with KOH, extracted with ether, which dissolves the non-sulphonated amine, while the sidpliouatod amine remains in the aqueous solution. The latter can often be combined with certain diazo-salts, giving a definite dyestutl' wliich may easily be recognised. ' More information on this subject can be obtained from such books as Green, Organic Colouring ^falUrs, and Lehue and Schultz, Tabellar. Uebcrticht der k-iinstl. organ. Farbstoffc mil angcf. MusUni, etc. THE ANALYSIS OF PYESTUFFS. 343 Wlieu a^jaj'adiamine is obtained (by the reduction of an amidoazo-compouud), this is recognised by the thiazine reaction, i.e. treating the solution (free from tin) with HCl and FeCl.j in presence of H^S. A ^a/'((diamine is also obtained by the reduction of a t/iVazo-dyestuff ; thus, for instance, Sudan III [A] on reduction gives y'N = TH.C^.,{,\\ ,NH„(1) /OH{fl) \N = N.C,„He(OH);8(4) " ^NH„. (4) ^NH., In the case of a dyestuff containing no amido-group, this reaction is helpful in distinguishing between a monosao- and a rfi'sazo-dyestutf'. It is also possible to decide whether, when an SOgH group is present, this is in the middle or one of the end radicles, fur the thiazine formed from a non- sulphonated diamine is soluble in ether (in presence of KOH), while that from a diamine containing a sulphonic acid group remains in the aqueous solution. The examination of mixiares of dijestuffs. — The difficulty of detecting and identifying dyestufts is much increased in the case of mixtures. A preliminary examination may be made by examining the powder under a microscope, or blowing a little of the powder upon sulphuric acid or moistened filter-paper, etc. Separation by means of water or alcohol may be tried, although mixtures of dye- stufFs usually resist this method of separation, owing to the similarity of the components. Much use, however, may be made of ether and wool in this examination. The free base of a basic colour is easily extracted from its alkaline solution by ether or wool. In the case of an acid dyestuff, the colour acid is liberated by means of a stronger acid, and then the colour (in the form of the free acid) is extracted with ether or wool. Both agents should be used, as some dyestufFs which are extracted with ether do not dye wool. Separation by means of ether. — The object of this is chieflj' to distinguish between basic and acid dyestufts. The former are extracted with ether from their dilute alkaline solutions, while the latter remain in the aqueous solution. Tlie operation is carried out as follows : — 100 c.c. of the aqueous solution of the dyestuff' is treated with 1 c.c. of a 20 per cent. KOH solution and shaken with three times its volume of ether ; this shaking is repeated with fresh ether until the latter is no longer coloured even after acidifying it (the etlier) witii acetic acid. The aqueous alkaline solution of the acid dvestuff' is neutralised with acetic acid and put aside for later examination. The ethereal solution of the colour- base is washed with an equal volume of very slightly alkaline water, and finally shaken with one-third its volume of 5 per cent, acetic acid. This acid sohition is withdrawn from the ethereal layer and evaporated on the water-bath ; the residue contains the basic dyestuff. Occasionally the dyestuff' remains undissolved by the acetic acid, in which case the ethereal solution remains coloured and must be evaporated on the water-bath in order to obtain the colour-base. A very few neutral dyestuffs are also extracted by ether, e.g. Quinoline yellow, Indophenol blue (spirit soluble), the different Sudans, etc. All these are insoluble in water and soluble in alcohol ; they are extracted by ether even from their acid solutions and also remain dissolved after treatment with water or dilute acid. In the extraction of basic colours with ether it is not entirely immaterial which alkali is used ; all bases are set free by potnsh. Other alkalies, such as, e.g., ammonia, are not in many cases suflicieutly strong. Other bases, again, are readily extracted by ether in the absence of any alkali. Thus, for instance, Safranine, which is a very strong base, requires the use of potash, while jNIagenta is liberated by ordinary ammonia ; others, such as the Indulines, Oxazines, and 344 SYNTHETIC DYESTUFFS. Acridiiie, are set free hy very dilute iiiuinonia ; and finally such colours as Chrysoidine, Bismarck l)rown, Uhodamine S [By], Victoria blue, etc., are dis- sociated in their aciueous solution, and the base passes into the ether, while the acitl remains in tiie water. This diderence is made use of in analysis. The dilulo aquouus solution is fii-st extracted with ether, and the extraction contiiuied (with fresh ether) after adding successively 1 per cent, ammonia, concentrated ammonia, and, lastly, L'O per cent, potash. A further separation depends on the dirt'erent solubilities of ba.scs in water and ether. When the etheieal solution is shaken with an equal volume of water, some bases pixss into the latter, while others remain dissolved in the ether. In this way it is possible to separate Acridine yellow from the very similar dj'estutl' Phosphine. The l)ases remaining dissolved in the ether can be separated by extracting with 5 per cent, acetic acid ; some are dissolved and can be recovered from the acid solution, while others remain behind. The acid di/estuffs which were not extracted from the alkaline solution by ether are se])arated by similar methods. The neutral solution is acidified with hydrochloric or sulphuric acid and extracted with ether ; the non-sulphonated acids are dissolved, while most of the sulphonated ones remain behind. Some, however, of the latter are partly soluble iu ether, e.g. Roccelline, Ponceau G [B], Wool black, Azoflavine, etc. This latter difficulty is overcome by the use of 1 per cent, acetic acid, instead of the mineral acid, when the sulphonated acids remain entirely undissolved by the ether. The aciddyestuffs can thus be divided into three classes, viz. : — (1) Soluble in ether in presence of 1 per cent, acetic acid ; (2) soluble in ether in presence of hydrochloric or sulphuric acid ; (;5) insoluble in ether. By this means we can separate Erythrosine [B] from Roccelline and Bordeaux B [A], also Direct yellow [A] from Congo brown K [A] and from Congo red [A]. If the mixture consists entirely of acid dyestuti's, we obtain a fourth class, viz. : — those dyestuffs which arc extracted by ether from the neutral solution, e.g. Sudan I. [A] and Sudan G [A], In this way Sudan G [A] can be separated from Victoria yellow, etc. The ethereal solution can in this case be washed with water in order to obtain a further separation, as already indicated ; thus, e.ij., Picric acid is distinguished from Martins' }-ellow (the free dinitronaphthol is only very slightly soluble in water), and Diamond black from iS'aphthol orange. Separation of (Ii/e.^» .2 ^ "n K S 3 .2 O 6 ^ » « 6' M «/ ^o" o\ /izi 0\ />5 /^\ e o \ / c« fc W^ bo o ?< s<_ s S ° "J T3 o ■^ « lU o S ^=' ^ CO 4.= g 0) Q 2 o 2 o i-3 4 f.^ -=1 = ?-3 s * = if SiS - g^ = fl £ o - -00 o ^ o --- o "30 '- «• + -'= o cfc *2 §7 I .5 = 3 t) j: ^ THE ANALYSIS OF DYESTUFFS. 347 .2 ^ •3 = i 5 «o =^iW 5 =, °? -s- ^""^M ^ :^M =:==^j_ -^ _a=^ ^i ^- £-.= 12 e |3 ^ill I Is iM = S-3>>-? , o o o S 3 i-^^ ,-jaq}a miji p34DBj;xa pus HOX mT->^ p3}B9J^ SI uoi^nios oiioi[oaiE jo snoanfiE ai]j^ 34**^ RYxrnKTir nvKSTrFFs. > H 1 C4 ^ 03 fa "A O S5 1 1 Ml/ \!/ o 3i 03 as \1/ O 1 1^ o 1 ■g colon CI). (not iged 1 g- . TWsi »!-aJ II o— o SB =-?2 f^afc "S^ "*"= aS r;=; ??f-5 S-^ i "^ 'ii 5^1 -ijij .-^.^ 52-1 .2 1- 11 l^f.-i" -i-J =31 =S >.= m /\ ^V ..^l i-Sa III =§5 -^ . 113 ^if4j« lis t- •g o l.i" 11.^ si-? I -I li§ -^"- *i;-^..>6a3w M s 111 .-11 1..- ■§i: 1=?. r>j ii=i.-="t5-. ^1. il'^Jlg 111 ■-.2 2 S % >,3 >. -r 3 ti * ?- 5 a. > io = M >. " 3: .2 ^.^ -: > 2 > i a^r 5? i. i- 5 2 ■io^ =^^ •-=-Tr ?5'^ £5=^.? •iio}}oo Oilid qji.w paijoq bj linisa.fp a 3 •joiiia mj.tt pa)Oiu)Xd pun HOH 4'5* P''4«a4) si ^injsj.Cp ai(} jo iiot4iiioii jiiu4oj|« jo siiujiibs aijj, THE ANALYSIS OF DYKSTUFFS. 349 o II « P5 ]/ \l/ \«/ /°x \«/^ o /\ \./ O o 02 ■ 3 "^ S •S ■^ ^j ^ -■_ o ^ «=■" "S o S ^ Ji ■%% o - +J ® .^ « DQ^ .'^ oes no solub] oence. absor' 1 > i 1 |l ssolve red-vi blue, colour Di -4J 09 Q £ Q O a> 1 •ja}«Ai Snijioq ai papiiadsns.to paAjos ■( '^tnaa 13d I 'hoS) ■R^'^I^ 1 •sip SI jgn^saip 31X ?lBaA\ qjiAi pa;Eaj^ si (jtqsa.tp" jEUiSuo aqx > > — > 1 'g ~ ■0 ■^'° a Z % ^ o Dp 3 = 3.3 5 a. s J> w lins unci: lienylmet ves con lido-grou coloured gn green. Oxykdone t it^g ^ P3H £ ■'•'103.1 .10 "Oimios (OOOI : I) a^nijp B JO sdoap Avaj e \^■^y& pa^Baj; si jjn^saip aqj jo uupn[os oiioqooiE aqj, CHAPTER XXXIV. INVESTIGATION OF DYESTUFFS ON THE FIBRE. The large number of synthetic dyestufFs, and the use of various members of them for the production of different shades, renders any identification of iliem on the fibre an extremely difKcult and sometimes impossible task. It is impossible, for instance, to determine the exact nature of the various dyestutt's which have been used to produce, say, a black or a green U|)on the fibre ; but it is possible, by studying the reactions on the fibre of the various types of the different dyestutt' groups, to obtain a fairly clear insight into the cliaracter of the dyestutt's that have been employed, and by these means to reproduce the same colour by the use of other similar dyestufi's of the same groups. In a few cases only, where a pure dyestufi' has been used, can its presence on the fibre be with certainty identified. In the first place, it is, of course, of importance to determine whether or not the dyestutt' has been fixed upon the fibre by the aid of a mordant. Tlxe best method for this jjurpose is to ignite specimens of the dyed fibre, and then to submit the ash to ordinary iiualitative analysis. Care must be taken, iiowever, that all weighting material, etc., used in tlio finishing of the fabric has previously been removed. This can usually be ett'ected by thoroughly washing the fibre with hot water, which removes the soluble substances used for this purpose, whilst the metallic salts used as the mordant remain unattackcd. The colour of the ash frequently indicates the nature of the metallic salt used. Thus, with iron mordants the ash is brown ; with copper and manganese, yellowish-green or bluish-green ; and with tin, aluminium, etc., usually bluish- black ; the presence of the metal must, however, always be confirmed by analysis. Certain substances used in mordanting, such as tannin and oleic acid, being organic, burn away with the fibre, and therefore cannot be identified by this means. Taiiii)r acid (tannin) is usually accompanied by antimony, iron, or tin. It can be detected by extracting different portions of the specimen with (1) hot water, (2) 2 per cent, sodium carbonate solution, (3) 5 ])or cent, acetic acid ; according to the condition in which the tannic acid is present, it will be extracted by one of these reagents, and the neutralised extract will give the characteristic tannin reaction with ferric chloride. Oleic acid usually accompanies aluminium or similar mordants. It is always present in Turkey-red dyeings, and can be detected by extracting with hot dilute hydrochloric acid, filtering, and extracting the filtrate with ether. Another method of identifying the mordant on a fibre consists in first destroying the colour with blcaching-powder solution. This can usually be ett'ected by steeping it for some minutes in a 1 per cent, solution of bleaching-powder, but if this is not suflicient, a stronger solution can be taken and the action of the bleaching-jjowder accelerated by the addition of INVESTIGATION OF DYESTUFFS ON THE FIBRE. 351 acetic acid ; under these conditions the fastest dyestufFs will be destroyed, and the decolorised fibre can be investigated for the presence of the mordant. Iron and chromium can be detected by the colour, although it should be remembered that the prolonged action of bleaching-powder may convert the chromium oxide into chromium chromate. Aluminium and tin mordants would leave the fibre colourless ; they may be identified by dyeing the decolorised specimen in Alizarine. In the following tables (Heerinaim) attempts are made to place the analysis of the colouring matter on the fibre in tabular form, according to the shade of colour of the fibre ^ ; and following these a list of the typical members of the various groups is given, together with their behaviour towards reagents on the fibre. The basic colouring matter can, as a rule, be readily detected by extracting the colouring matter from the fibre with boiling alcohol and redyeing cotton mordanted with tannin in the solution thus obtained. I. Red and Red-brown DyestuflFs. The coloured fibre is lioiled fur some time witli dilute alcohol and a fairly strong solution of aluminium sulphate. F = fibre ; S = solution. Nothing ex- Yellow to red extract without fluorescence. tracted. . Sodium bisulphite solution is added. Eosine, Safranine, Rhodamine. Immediately decolorised. Not decolorised. Magenta and Acid magenta and vegetable dyestutfs, Santal, Redwood, and Safflower. Anthracene, azo-, and Benzidine dyestuffs, also Cochineal and Archil. Boil with dilute alcohol. Boil with very dilute hydrochloric acid. Red extract. Little or no extract. F, unchanged. F, darkens (brown to blue). F and S, yellow. Alizarine, Alizarine orange with Chrome mordant. Magenta and Santal. Acid magenta and Redwood or Safflower. Azo-dyestufJs or Archil and Cochineal. Congo red, etc. Heat with a dilute solution of lead acetate. F, unchanged. Azo-dyestuffs or ArchD. F, dark brown to violet. Cochineal. It must be remembered that the dyestuffs mentioned are merely types 352 SYNTHETIC DYESTIFFS. II. Orangre and Yellow Dyestuffs. The coloured fibre is treated with tin chloride and hydrochloric acid F, unchanged. S, yellow to colourless. F, colourless. S, colourless. F, first red to blue-red, then decolorised. F, light yellow. S, yellow. Vegetable colours and some synthetic dyestuffs. Chrome yellow and azo-dyestuffs. Fast yellow, Me- tanile yellow, Orange IV., and Brilliant yellow. Alizarineorange. Heat mth KOH. Heat with ammonium sulphide. F, red or brown. Little changed. Unchanged. F and S, red. F, blackened. Certain vegetable colouring mat- ter; Fustctwood, Curcuma orange (Cochineal, Quer- citron). Quinoline yellow, Phosiihine, and certain vegetalile colouring mat- ters ; Quercitron, etc. Naphthol yellow S, Auramine, Tartra- zine, Azoflavine, Orange II., Gal- loflavine, Chryso- idine, Chtyso- pheuine. Picric acid. Chrome yellow. III. Green Dyestuffs.' The coloured fibre is heated with dilute alcohol. F, colourless. [ F, coloured green. Na]>hthol green, Cterulfine, Fast green, or mixtures of Indigo or Logivood with yellow. Brilliant green. Malachite green, diethyl green, Alkali green. Light i green. Indigo carmine + Picric acid. Indigo carmine + Quercitron. 1 Heat with dilute HOI. Heat with dUute HCL F, blue. S, yellow. F and S, F, unchanged red. S, yellow. F, decolorised. F, lighter. S, yellow. S, blue. F, little changed. F, decolorised. S, yellow Indigo mixed with yel- low vege- table dyes or with Chrome yellow. LogAvood Ca'ruleine. with yel- low vege- table dye. Naphthol green. Fast green Indigo carmine -l- Picric acid ; Indigo car- mine -f- Quercitron. Light green S, Alkali green. Brilliant green. Malachite green. Methyl green. ^ Green dyed fabrics ore frequently produced by mixing a blue and yellow dyestuff. INVESTIGATION OF DYESTUFFS ON THE FIBRE. 353 IV. Blue and Violet Dyestuffs. The coloured fibre is boiled with dilute alcohol and a few drops of hydrochloric acid added. No change. F, blue ; S, blue. F, unchanged. S, yellow-red. Alizarineblue and other Alizarine and Anthracene blues. Indigo carmine and most synthetic dyestuffs. Alizarine violet, Galleine, Azo- blue, and vege- table blues, such as Logwood, etc. Treat fresh test-portion with concentrated sulphuric acid. r. „ J a F and S, yellow to F and S, green. trown^red. F, unchanged. S, blue. Methylene blue, etc. Spirit blue, Water blue. Alkali blue, Methyl blue, Victoria blue, Methyl violet. Acid violet, etc. Indigo carmine, Induline, etc. V. Black DyestuflFs. Boil with dilute hydrochloric acid. F and S, red to yellow. F, unchanged. Alizarine blue, Resorcin blue. Logwood, etc. Aniline black, Naphthol black. Brilliant black, etc. 2Z 354 SYNTHETIC DYKSTL'FFS. VI. Brown, Grey, and Mixed Colours. The coloured fibre is boiled with a dilute solution of oxalic acid and allowed to remain in the solution some time. F, unchanged ; S, colourless or only slightly coloured. F, nearly de- colorised ; S, practically colourless. F, lighter in colour ; S, yellow-red. Warmed with SnCU + HCl. F and S, colourless or light yellow. Orange II., Naphthol yellow S, Tartrazine, Fast red A, Biebrich scarlet, Indigo carmine, Magenta, Light green S, etc. F, first blue-red, then de- colorised. Orange IV. Fast yellow. Brilliant yellow. FandS. iF.Miegrey ,, .to blue, rfd re-formed I by washing. Acid, Magenta, Red-violet 4RS. Induline, Fast blue R, Jlethyl violet. Acid violet, etc. The sample is again boiled with dilute sodium carbonate solution, the solution treated with zinc dust and HCl, and filtered. Colour does not return on exposure to the air. Azo- componnds. Red-violet 4RS, Acid magenta. Fast blue, etc. Colour returns on exposure to the air. Indigo carmine. Colour returns on neutralising with sodium acetate and heating. Light green S, Induline, Methyl violet, etc. Chrome, iron, and copper lakes of vegetable dyestuffs, etc. Iron, copper, and aluminium lakes of vegetable dye- stuffs. Synthetic dye- stulfs mixed [ Boiled for some time with these can i ^th potassium ferro- be extracted from the fibre w^ith alcohol. Basic dyestuffs present with these, in the form of their tannin lakes, are separated by boiling with caustic soda, filtering, and neutralising. cyanide monia. sol. + am- F, very slightly changed. Alizarine, Alizarine S, Galleine, Gallo- fla%-ine, etc. F, lighter. Alizarine blue, Coeruleine, Alizarine black, etc. INVESTIGATION OF DYRSTUFFS ON THE FIBRE. 355 M ..■g®|-s I'B + ll e, u •s* . ■5-5.1 ..ml ;;z3 >* S" & .i"i Benzo bla •a •3 oafssse S 00 lis. oS + ll 3 a 5 T3 'S'g + a • „ Is .-« g a j3 IP u ^ a> n 0) a = g ilP 5 = -g In ? II 3 ^ ^ ilHli^ ..111 •0 111 .'. "3 ■§ tA "? a °-l |~ = a a =.-.«l S1^ ■?,■<» 11^ T3 a S fl a S3~ = + 1 TiT £ °!2 5 I111 ■s -• •Ss2 11 ss I*!" = "S a ■a o^ Ifi = 43 |1 II ■Soil |.Sz.s|S3. 1 S 11 ■ -.ox^o ■§7-"+£ a ^ „. ■6 _■ sag = = 2|i c s a •g "= . ^ 2^ 2 + «-g .a «^-<=" Jo a « _a ■ » 1-^ U. 1- X is- 1^ « ■= Ul 356 SYNTHETIC PYESTUFFS. Reactions of the more important Dyestulfs on the Fibre. Iii;o. 4.) Knecht recommends titanous chloride as a reducing agent for testing the nature of colouring matters on the fibre. Azo-fli/ei', on cotton, are almost instantly discharged when boiled with a dilute solution of titanous chloride ; I'rimuline red is discharged to a yellow ; Para- nitraniline red is discharged white after boiling for about two minutes ; whereas tt-naphthylamine claret (diaz.otised j8-naphthylamine + /i{-naphthol) requires a longer time for its destruction. Primulinc (undeveloped) and allied colouring matters are not affected even on boiling fur some time. Jiasic colours;. — These colours dyed on tlie usual tannin and tartar emetic mordant are in most cases comjiletely destroyed, the fibre remaining a dull yellow to brown in consequence of the formation of tainiate of titinium. Except in a few cases (llhodamine, Thioflavine T), the colour is not afterwards restored by washing in running water, or on treatment with dilute hydrogen peroxide, the reduction having gone further than the formation of the leuco-base. Sulphide or Suljjhur colours. — The sulphide colours are readily acted upon by titanous chloride on being boiled in dilute solution ; they rapidly lose their characteristic colour and tiirn brown or drab. At the same time sulphuretted hydrogen is given off, as in the case with stannous chloride, but more readily than with the latter reagent. The presence of sulphuretted hydrogen can be readily detected by jilacing a piece of lilter-pajier moistened with lead acetate over the mouth of the test- tube in which the fibre is being tested. In using titanous chloride instead of stannous chloride in this reaction, it should be noted that this reagent frequently evolves traces of sul]>huretted hydrogen, the origin of which is not known ; hence, before using it for this particular test, it should be first boiled for some time with the addition of a small quantity of strong hydrochloric acid. The sulphide colours are not permanently desti-oyed by the action of titanous chloride, and the colour is restored either by washing with water or by immersion in dilute hydrogen peroxide. Aniline black. — This "colour behaves in a very similar way to the sulphide blacks, turning to a brown or drab, which becomes black again on washing in lunning water or exposure to the air. It is important to note that most Aniline blacks also give off small quantities of sulphuretted hydrogen. The aniomit is certainly nothing like that evolved from a sulphide black, but the circumstance must naturally be taken into consideration when discriminating between the two classes of blacks. hiiligo. — This colour is lirst converted by the action of titanous chloride into Indigo white, and the fabric, if taken nut after not too long an immersion and placed in dilute caustic soda, will yield some of its colour to the latter. But if the material is boiled for more than a few minutes, the reduction goes further than Indigo white and the dyestuff is completely destroyed. INVESTIGATION OF DYESTUFFS ON THE FIBRE. 359 This action of titanous chloride is of considerable importance, since it enables the chemist to easily and rapidly detect the presence of sulphide colours which have been used as a bottom for Indigo, or which may have been used along with Indigo in the vat. Turkey-veil, when heated with titanous chloride, becomes maroon, presumably in consequence of the conversion of the alumina lake into the corresponding titanium lake of Alizarine. Spectroscopic Investigation of Dyestuffs. (.1. Formanek, SpektfalanalytisrJier Nachweis kiinstlicher organischer Favbstoffe ; see also Zeitsehr. Farb. u. Text. Chem., 1902-1903.) As far as present investigation goes it would appear as if the spectroscopic examination of the dyestufl's, both in the solid form and upon the filjre, will ultimately constitute the safest and surest method of estimating their character, both as regards the nature of a mi.vture as well as the probable chemical con- stitution of a homogeneous dyestuft'. It has been noticed, bj' comparing the absorption spectra of the various groups of dyestuffs, that the presence of certain atomic groupings produce characteristic spectra, bj^ wliich the presence of such groups can with con- fidence be predicted. Thus solutions of triamidotriphenylmethane dyestuffs show two unequal symmetric absorption lines ; the Thiazines two unequal asymmetric lines ; the solutions of Alizarine dyestuffs three absorption lines ; the solutions of the azo-compounds one or two broad absorption bands, and so on. This method can be applied not only to the solid dyestuflPs, but also to the dyestuffs on the fibre. In this case the solvent used may be either water, absolute alcohol, equal parts of alcohol and water, 90 per cent, acetic acid, or equal parts of aniline and acetic acid— solvents which w'ill be found in most cases effective. In order to extract the dyestuft" from the fibre, it is first boiled with absolute alcohol ; if the fibre is not completely decolorised by this means, it is further boiled with acetic acid, and finally, if necessary, with the mixture of aniline and acetic acid. By this treatment it frequently happens that a mixture of dyestufts is separated, owing to the different solubility of the various constituents ; thus, if a rtbre has been dyed with a mixture of Methylene blue and Methyl violet, the whole of the Methyl violet would be extracted by the absolute alcohol, whilst the Methylene blue would only pass into solution when boiled with dilute alcohol, or, better still, with acetic acid. The solutions obtained by the various solvents are then subjected to spectro- scopic examination. If tiiey show similar absorption spectra they are mixed and evaporated to dryness, the residue being subsequently extracted with water, ethyl alcohol, and amyl alcohol, and the solutions obtained again examined by the spectroscope. It is frequently possible to detect the presence of a mixture by merely examining the solution of a mixed dyestuff by the aid of the spectroscope. This is especially the case in respect to the Triphenylmethane dj-estufts, the Quinoneiraide dyestuffs, and the Acridine dyestuffs, the absorption spectra of which are clearly and sharply defined. The presence of a mixture is usually indicated by the unequal arrangement of the absorption lines. Thus if the spectra shows two clear, well-defined lines 360 SYNTHETIC DYESTUFFS. on eitlier side of a weaker one, the presence of a mixture can with confidence be suspected. In cases wliere the absorption lines of dyestuffs occurring in a mixture mask one another, it is often possible to separate them bj means of acids or alkalies. Thus, in a mixture of Induline and Methyl violet (aqueous solution) the absor[)tion line of the Methyl violet would be covered by that of the Induline. If, iiowever, dilute acid is added to the aqueous solution, the line of the Methyl violet will travel towards the left, and the two lines will be clearly visible. Amyl alcohol has already been mentioned as a valuable means of separating mixtures of dyestuffs, and it can also be used in connection with their spectro- scopic examination, since, after extraction, the amyl alcohol solution can be directly submitted to investigation bj' the aid of the spectroscope. Thus if a mixture of Nile blue A and Methyl violet is treated witli amyl alcohol, the Methyl violet dissolves, leaving the Nile blue uuattacked. The basic dyestuffs fixed on cotton by the aid of tannin and tartjir emetic can be investigated in the usual way ; if, however, aluminium, iron, chromium, or tin have been used as a mordant, it is advisable to evaporate the acetic acid extract to a small bulk, add water, then carefully extract with amyl alcohol. The amyl alcohol will dissolve the dyestuff, leaving the mordant in the aqueous solution ; the two can bo separated by means of the separating funnel, and the amyl alcohol solution subjected to spectroscopic examination. Reactions of Dyestuffs on the Fibre. In the following tables the reactions on the fibre of a few of the more typical dyestuffs are given. The tables are divided into sections depending upon the colour of the dye- stuff. In the first part of each section will be found those dyestuffs belonging to it, which are mordant colours for wool, silk, and cotton ; and after these will be found the direct colours for those fibres. The test is best carried out by placing a small portion of the dyed material in a white porcelain dish and covering it with about Ice. of the reagent; the changes given in the tables are those which take place immediately or shortly after the reagent has been brought in contact with tiie fibre. Rewjents. — Concentrated H ,SO,. 10 per cent. H.SO^. Concentrated HCl. 10 per cent. HCl. HNO3, specific gravity 1--10 (Tw. 82°). NH3, specific gravity 091. 10 per cent. NaOH. I 100 grams SnCl„. SnCI, + HCl 100 grams cone. HCl. ( 50 c.c. water. F = fibre, S = solution. Colours investigated by Knecht and Rawson are witiiout mark. * Indicates colours investigated by Lunge and Gnehm. ** Are colours investigated by Unehm and Surbeck. *** Are colours investigated by Heermann. INVF.STIGATIOX OF DYESTCFFS ON THE FIBRE. ;6l Literature. Jonrn. Soc. Dyers and Colorists, 1900, Xo. 48-58 (Jan.-Nov.) ; 1901, No. .59-66 (Jan.-Oct.). Manual of Dyeing by Knecht, Rawson, and Lowenthal. Lunge, Clieiiu^ch-technisclie Untersuchu7igsmethoilen (Gnehm). Gnelam, Taschenbwh f'iir Farherei uiid Farbenfabrikation. Bliimer and Kolle, Fiirher Zty., 1899, 240, 258, 273, 288, 306, 326, 346, 364. Heermann, Kolorisfisclie und texHlrhemisclie Unfersnchungeii . [Tables. 362 SYNTHETIC DYESTUFFS. ^• tt tB-- ■t > T! -3 1 + C s ^ > ^ 1 .2 rH* g-= f ^ ^ — S ^ •- a ^ « •-, S u OfeM Q U « Q Q h ill T) a 5j 3. ll 3^ ^ 0.' •03 3 .2 — 3 p C^ xn hen fe oc fe-of face feTos" a; bic ■? 3 1 tc 1 1 1 eS . •i 1 Be ij'^ s 3 &r 33 1 1 uToc 2 3 M>3 fe." CO & II ll , - S 2 1 J"! i 2 ll S H >H S .3 >• pS Ix >< *;• ^0 1 S.W 1 1 1 1 1 1 1 '" c §0 T3 ■5 3 ll 1 3 S S: -g ? « 3 2.2 , 5=3^ .0 §•> Ph oq" fe of Cm" of C]^ tc t^'-yf &H 00 ^ 1 1 1 ^• 0. ^ 1; §£ 1 a ^w 1 ' > s_« s •3 ' (S fe oT S' B ^1 . 1 3 >^ il >• ^ 0) 60 I ■3 s II ri" % _3 . •c-S ll •a3 ^3^ 3 ^^ 3-a g £ C 1 a. y 3 1 is L-g 3 . 11-2 -3 2 &1. c/: m u. x' &.!» fa of faco _3 3 6 ^ •5 c •5I E 3 1 ^ if If ^1 II. .§13 1 |6 1 ^ ^ _^ a, ^ 3 "•S-t ^ .5 E n < %^ "c 1 i 2 l-g Q 1 "3 c 1 S-.E V 3 1, P 1, ^C2 3 |g3 5 INVESTIGATION OF DYESTUFFS ON THE FIBRE. 363 ■ &■ ■d &D_C c 60 1 1 § j3 t». S c s 1 ' £ tu QJ -C s ' ' a" 60 £•5 j= 1 1 60 3 s C M ij 3 m « tfl t£ ■a" -g •d "S OT Td a> a> m Si: § ■a 61 1 _6p t^ ^ 1 CO ■a 1 ■a 60 5 1 1 -a CO ■c , 60 "He (^Tar fa erf 55 Q s fa" 03" fa"ar fa" of fa"Gc" 3 TJ ^j TJ •a 7 T3 V 3: ^* 1 ^* 1 CO .2 •f^ •g t. 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"S ^ ■il 1 > a il !_ 3 3 =3 3 1- 1 ■>03 3_l *> ^"^ fa fa fa iz; a -< ■< fa 364 SYNTHETIC DYESTUFPS. . •D s &£ H . a . 1 + J" 1 &> __. 1 1 j; a 3 f; OS S3 « ^ 5 *i •0 ^j i CJ c >; H 1 1 >> , "Z 1 1 1 3 s 3 -S bO S 1^ ' ■g ' -a 1 H > 1 III faOT" fcTtn PtTm" fa m" faof fa of & S „■ 1 t.- 3 l^r^ 1 -^ "S 1 i: '0 i -S3 •2 1 60 So [5) r3 1 2 ? £ 2 •^1 i|' feco" feCC fcTco" ixTtn faoo" fa"ar fa" 00" ^ Sc „• P, :S J= "2 " s 1 M 1 ^ ? ^ SJO ^■^ is '3 .J +j -i ^ s O'Ah s S P^ Q ^ h 3 »9 O) f-. 1Z bo §__ >: A » >^ ^ +i a S-i 1 1 1 1 1 1 1 "2 aw 1 1 1 1 1 1 1 s" &t J c f-4 a> 1 1 i 1 3 i g 3 3 1 £3 _3 *^3 1 1=1 1 %r bC x" fc yf fe of &."(» CtTaT fa oq" fa" 00" A 3 M So' 2 ^ 3 § & i 1 1 3 « 3 ^ s -3 3 s 13 0* 7 ■a" a >- l| 1 %" %-^ ! 1 ^ >. t ■3 1 ■4-i |1 11 a ^ It" ^ ="l 3. 2 2 ^ •£ '5 i X s 'S -s M C ^ _3 tC ? ^ -Sc — ^^3 — 3-0 — fcT oT liT 03" &<"(» fe M CtToT fa tc fa" 03" cc ^ ^ g "g 1 "o ;^ s^ (a 1 3 &_ a 1^ !_ 3 1 Si" 1^ 1 3 3 1 3 •a p2 ^ > > '^ fa INVESTIGATION OF DYESTUFFS ON THE FIBRE. 365 aS CO § d 1 "S •i 1 1 ■g 1 J 1 C bO a ,2 1 so 1 § 1 a S ^ 3 i "5) i a ^ 03 ij t) TJ bS -tJ oj OT a t d 1 ^ si. is .3 1 aJ 1 3 -2 1 3 "a, 3 1 '> 1 .3.2 £ § ^ g -a .3 -a 3 p< p- ^ b^ fazD fa" cc" fa" OT fa'cc" fa" 03~ fa"a3" fa 03" fa" ai 03" .u m 13 ^ S „• 1 ^ 1 1 1 1 , 1 1 c. §0 3 1 c ' ' i •a ' ' ' &r /T fa" 03' fa" 03 fa"o3" fa" 03 1 = i 4^ ■7T Si .15 -a 3 J ;§ a" V .3 1 1 1 ^ So >^ S) >. i ^ 3 OJ bb 4< Q >H 03 a 03 Q 7 7 1 7 1 1 1 7 1 1 3 £ _2 c: _3 g- t:_3 3 „• 3 £ 1 S3 ■i •3 ls| ^ 1 J3 bo S) i «; 3 1 3 1 1 +3 3 'C DC TJ £ -5 £ -^ J X ■a P ° S M •3 >> 'w ja r^ Mg^bog, -0 3 ■0.0 ■^ 6=103 fa of £^ 03 fa m" fa" 03" fa03 •* 03" fa 03" OJ C ® ^' SO ^ =^ & ^ £3 23 "0 ""^ 15 1 ^ 3 s 3 M c ■§) If 1 J fa 03" face faoT p -^? a5 »J g _. .. 5 1 „■ 3 1 § ^ "S i si bo ;; 1^" '' a 3 b 2 1 ^ ^• 3 . s J4 oJ .3 ■1 s Ji 3 J > Si) "S '^ •a-a ^ — "o 'Ti := c^ 3 3 ^ P i 'zl « 3 3 be S S 3 3 >. '3=: .Q § 3 •S'S 13 .£2 ° 8 1 •3 >> ■a 3) 6C fc^ 3 T33 T3 J3 "^ bii^3 3 £ >-> fa OJ fa" O) fa 03 fa of face faoT fa" 03* fa" 03~ 1 3 3 § f 3 03 ^^ 03 3 1 "s _! ,^ 3 3 3 3 ,A 2 ,_:; 3 fl.S jl a Sij J, '3 3 .33 (2^ 1 ■a 3 1 a T3 3 11 j66 SYNTHETIC DYESTUFFS. o •s^ ft .* ti H c-| c 1 "S 1 1 t ■a 1 + 1 " .'^ 'C 1.S ■E ri . •2 'E f MIS _o o _o ^fc _o s3.a o _o _o 1^ T3 8 ti §1 m s: Q Q Q a Q t> Q Q s i 2 i .3 1 1 a S e •a S t *> i i 3 3 3 |g o £ g =* 3 .a i 2 •e i Is i Li '^ fa of fa" n fa'oQ fa"af n il P fa'oo" fa" of &: t^r^ i . ■f ^' 3 . 1 & & 1 t^ 3 1? r ^1 1 1 i S 1 '> i i 1 ' § 1 ' li &r OQ fa" n fa"(n fa"oa fc :! fa"o!f fa"of ^ >. JSTS A . M "i '^' Id :s£ m O *; ji C S K C A 'o'o i i 1 si 2 c: CO ^ TV •S "3 "5 i -=3 £ £ s n fctoo" « t- ?" ra fa'cc" o ffl O +i d "S !-• . , 1 . 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Oh a _g ls| § i ■| T3 & a a O a 1 1 g-2-; 1 "o S ,^ &-; & § gs 5^ § " c "S *c bC-o 3 1 3 'Z a 2 c o 1 loi ■u o o ■a Q iS >3 >3 £ a INVESTIGATION OF DYESTUFFS ON THE FIBRE. 373 2-^ 1 1 M 1^ ta 3 1 1 1 1 -tJ +j Q " >> > § ^ i s ^ ^1 H 4i 1 Si ^ 3 ? W |55 d 8 . d s 2|> •P >-. ■p ' t; ^'■■S & a a 8:5 Eh oc PsTcO M Bn f^ m &i tc ft^tc fe02 to fn _3 3 v" § o a3 !>> ,a .£3 ,c ■^ » ^ o ;z; . 3 >> cc — -fJ a F 3 a ^ g o o" ■3 3 i "^ •° 1 1 H 3 u 3 03 t3 llglg .2fc c ifi ^y 5 i TS t3 !>>-a ac— •° p.^ a -■g >"g .2 -a g ^ g •^ a " 'o-f:-o C& tZ3 feToo tc ^ fe fe cc |i< Ul [i. oo ^'' of ^ g ^ nTJ'o" a ^T3 .15 fH 33 i. 1 ;=^ a ^"o ^c «a g c 1 1 a i ^ te i; 3 111 5 II 1 s i la 3 £ 1 III .S— s 111 )74 SYNTHETIC DYESTUFFS. 5 M + o 1 UDg 1 1 •^1 •1- i 1 1 a CO O-O c-o o m O > O a ■*•» r^ ^ "S •s c , • T- £ c-> ^§ ^ 1 4 ,2 1 &0 1 ll ^ -g i\ •il = 1 si ■o —• C E ' § ' 5 1 3 > s 1 r 1 £ 1 J3 ■^ fem" :-"-/:- ■j: ^" ■yf Si" to" few" feToB" eCeo" PsTgo" »i^ s> u) _>i i-" a: 1 to oj -3 |l 1 I 1 — c "? 1 i i' t^ ^ fex — x" to" E-" to" —'to" -" to" esTto" sTto" SsTto' 6^ to •a i 1 >> > §3 'l 1^ c E =3 3 II tl ^3 ll |-5 1 Is - 5 S H «" O 5 Q o >- o >" _^ c Ot— i ^O I 1 1 SA 1 1 1 1 1 1 1 1 1 o ■^ §' J 1 i 3 '^ ^ i 3_= 3^ H 3 •S 1 ■i!5> ^ •s o - g" "s^ a z ■^S j< ^. _5) E 1 C3 t- a'^ d M _o 3 M a 5 "a a o •a^ ■a S •a > S * rs b •3 = •03 O feToo" feT » feT of faTO" fcT »" fcTx" eCoo" tC TO* S:rTO" +i c ^ 1% 1 c d 5C 5 1 1 ec ^ ^ 1 •g 1 1 •g o 5 - o * o c fc iz; ^ »5 K O ! T3 11 1 1 1 ^ ^ j: 5'S .5 .S i 1 1 = -°3 a § pS c i Cm or," ^1 1 •5 to" '> a tT 1 to" ^-'to" ■Is faTO" feTTO" fe"TO" •a 13 fcTTO" 11 . "T ^ ? ea CO S S3 "— ' d 5 9 (B g| si J^ ^ 'f ^ "J^ ■| 1 si E • •if 'c a: = ^ g j ■c i ■is .a 5 1 31 < 1 < £ 1 f* INVESTIGATION OF DYESTUFFS ON THE FIBRE. 375 -3 1 i-a S) T3 "S "^ 8 » .s 'to 1 3.2 .a >> 1 .2 J tS O" >J Q Q *J -d tI) 3 .2 ^ .a i' c" 1 £ -d ^ ^ 1 2 .i s 1 T3 -3 ^ 1 1 1 "^1 §> 5 1 BO '> S -^3 £■5^ ■a .a " -a ^ -^ 2 f^ai fet/f feT cc" Eih" to (iTaf 6:^01" 6^" t/T fa of -o 1 2 M'3 .M 1 tl-^ iy i !»■ n 50 . .aS T3 ■5 ■2 S ^ -a 3 ^ ■a S ^ "o '-I ^ZD fet/T &C /f p=r cc f^zD feoT fecc fa m" « :§-2 .a .jS •"^"S — >< >-i — >H 1 — 3 -^ ?■ - — ^ p — £ ^ -a.^- c3 ^ 1 5 EllD oj _ t^ +^ 3 >.g 1 > S a. ^ S . 3 -2 'wi >> '^ -r; .2 o — t3 s -a s M a & £ S ^_S S.5? ^ 3 ■3 = 1 >, sCaf in'tC c=r af sJ'm E=r cc ■^ ^ af fa ao" S) >> ■ T3 ■ '3 to ap ac "S oj © (D s .a £ ■3.2 -an ^ "uj .a 1 1 1 _>> '§3 ■?3 •c _o u » ^ M « 113 iS OT m i M ^ . ■3 _s ^ '^ >> M 2 .a 'qj >. £ 2P .a s 3 1 ~ _2 3 '3 3-3 £ > ■^ 5 1 _3 "3 aJ ac a >> >1 3 ac'g i 11 4^ oT M • .■ E a a p=3 33 ■a -J '> •a 3'>-S a 3 g s s s ^ t.S ' ■^_ = S 3 ^ EsTaf p=r gq" f^T of tC of feT tzf e^" oT f=(" 03 g ^.4; __:; g s' =^ 1, > ^ ^ !_ _!_ S3 ^ _! SS^ < "9 t3 ■3 1 1^ a (S p ^ .a X § > -W "m q 3 •^ >> ,d ^ - ^ ■< < w W ^ 576 SYNTHETIC DVESTDFFS. 5 ^ + •i i; i a t C k* ^* _0 -2 S s >. S a o 'c "So ■^ s "F ■a ^ a g - S to _to OQ Q £ 1^ X Ij '•2 is 1 tl-O tn t: 2-S | A hf° is =3 g 1 ' 1 1 i| ' C C feoT ^* of 3 fe 00 fe 05" bc s- •d M d oo £ r g 1 1 1 'i S 2 |i M pS >> o [2 >• faCQ +> § li a E-W O 1 1 I'-s ! § Si § 1 1 o ij (^ 5 s 1 >> « * t>»-, - H Is s a 1 1 >. §o°.2 § s §:°.2 _ . 2 i i-f 3 ^ 1 1 3 t; S S^ 2 1 || 1 1 6 'u t ■5 ■5 = ^^ ' fatn fcT 33 ca P- fe." zT &." oT -;■ us sc 11 i 1 c a — [ij It "3 ■s, ^ "o t' - o « •c ca 13 il (S ::£ o* B § 3 § § ! •5 S 1 11 1 3 1 ■5 J >. 1 3 1 s 1 5 l.i Ml o'-S . >>? S >>^ 2 5 Sm CO" iC m" o Q fcT CQ fc 03" ~ i O Pi ^ ^ ^ ;:? a ^ « « n bC c Is ,3 £-5 3 3 E ca 1 1-5 •is li II s M j: K S (4 0: INVESTIGATION OF DYESTUFFS ON THE FIBRE. .377 . TJ . 13 Mm j2 1 '^ ■a ■^ ^* ■S.s •S'§ 3 T •c •" ■s .2 >>§ >>o I"! n > ^ O ^ "ig "? o .a a > S 1 5 § QJ §0 1 g 1 jj il =3 s ^ 1 "I "*- 'C 1 fl 1 4^ [3) o X 3 S J3 f^ /f fa of fa of il" Q fa" of fa* of fa" oo" fa'oT fa" m ■^■6 -a-a" i 3 M ^» 1 X 1 Qi 60 . 1 I *© 3 £ '« r^ >^ ■a «)>.& >) s ^ 1 1 •o" a 3 "3) 1 1 1) !x n fa IS pa O J tS >> h3 oS bO ac .a J !z; ^° ^" s 03 oj o3 ^ ai 3 m ^ »■ ra :=: ;i^ .H _3 « M 3 1 ^ 1 ^ r^ 3 ■r; -S 7:; +J '^ il -77 M a5 A 3 3 -3 3 OJ 3 ^ •— >^S. S 3 to • _2 > ^ 60 .o .&,§ >>p< -aS 3 ■W ■a § 3 § 3 g %i 3 S Lh ^ Cayj fam fata o e faM fa 02 faO! fa" of fa"tB 'S 3 3 S? . 5? » £ "■ M 4 1 S3 3 ■^ 1 1 1 -^ ^ -^ 3 g 3 1 § J3 3 3. 3 3 3 3 •s fe" ta" Pa affa^oT 13 ll Ph CL, Q c S +j 3 -c % % 3 3 _3 "60 '73 11 is 1 =" SbSb i s iT n 3 a5 3 3 3 §*£ 3 §•§ t>> ^^ 5 ao ■a ;3 ^ ? •a j2 0) ■a 3 ■a3 ■S3 3 ■a3 pi^r af feof fa'cB >< M fa' of fa* af fa" of fa" of fa'of T) -3 •a ^ OS P9 pa ta 1, ta "a" § "c" ■^ xo !?; 60 -g 1 O 1 5 -a §) 3 - -a a ° 1 1 1" 1 '^ II 'g •a s. M .3 1 % 1 S3 S '^ m f a O « K Q P 378 SYNTHETIC DYESTUFFS. Q ^- o! o CO H c + 1 ^i c •^ J" 1 -2 ■2 0) ? "So .^ ^ S ^ •^ lj !> So ■a 1 1 1 1 |i 3 cj " fe of faoT fcToT ftrof fa'af ^ g S""' ^ 1 2 5 B •*< 'S '^ S S r 'c'3 f II 1 1 •-1. E C « psTco faoi" faoo" fcToT fa" 02* ilO x4 C3 li B. ^T3 ">o 1 S^ [ ■3 B ' =3 s ' 1 !§! H >< Q o ^ " *5 C © . O 1— 1 ^o SW 1 1 i 1 1 o '"' i 1 4 c II t^ ■^ ^ •^ «5 ^ M V ^ a! 6 •T3 ^ a S » •a g S si 11 d » T3 J feTaT fcT OT bTaT fa CO fa"oQ" *i & oi a . a d ■J c? u A 00 11 ■SI to to o" t^ " ^ f!^ fam" !2; !z; O ! T3 to is .. § J' — 8 £-0 ^ ~ to 3 ll 6 fa" of ccTof Ca oT fa'ai" fa" of i o O s 1 o t- c ^ 5 1 o o c 3,^ i c » iS'^ '>*^-^ Q 11 2 1 |£ S §1 11 Q £ iS'"' « Sz; APPENDIX. TABLES, Etc. International Atomic Weights. = 16. H = l. = 16. H = l. Aluminium, . Al 27-1 ^6-9 Neodymium, . Nd 143-6 142-5 Antimony, . Sb 120-2 119-3 Neon, . Ne 20 19-9 Argon, . A 39-9 39 -IJ Nickel, . Ni 58-7 5S-3 Arsenic, . As 75 74-4 Nitrogen, N 14-04 13-93 Barium, . Ba 137-4 ISiJ-Jf Osmium, Os 191 189-6 Bismuth, . Bi 208-5 S06-9 Oxygen, 16 15-88 Boron, . B 11 10-9 Palladium, . Pd 106-5 105-7 Bromine, . Br 79-96 79-Si; Phosphorus, . P 31 30-77 Cadmium, . Cd 112-4 111-6 Platinum, Pt 194-8 193-3 Caesium, . Cs 132-9 131-9 Potassium, K 39-15 38-85 Calcium, , Ca 40-1 39-7 Praseodymium, Pr 140-5 139-4 Carbon, . 12 11-91 Radium, Rd 225 n3-3 Cerium, . Ce 140-25 139;.' Rhodium, Bh 103 102-2 Chlorine, . 01 35-45 35 IS Rubidium, Bb 85-5 84-9 Chromium, . Cr 52-1 51-7 Ruthenium, . Bu 101-7 100-9 Cobalt, . . Co 59 sss--> Samarium, Sm 150-3 149-2 Columbium, . Cb 94 93-3 Scandium, Sc 44-1 43-8 Copper, . Cu 63-6 03- 1 Selenium, Se 79-2 78-6 Erbium, . Er 166 lGJf-7 Silicon, . Si 28-4 28-2 Fluorine, . F 19 18-9 Silver, . Ag 107-93 107-11 Gadolinium, . Gd 156 154-S Sodium, Na 23 05 22-88 Gallium, . Ga 70 69-5 Strontium, Sr 87-6 S6-94 Germanium, . Ge 72-5 7-2 Sulphur, S 32-06 31-83 Glucinum, . Gl 9-1 9 03 Tantalum, Ta 183 181-6 Gold, . . Au 197-2 195-7 Tellurium, . Te 127-6 126-6 Helium, . He 4 4 Terbium, . Tb 160 158-8 Hydroijen, . H 1-008 1 Thallium, Tl 204-1 202-6 Indium, . la 115 llJf-1 Thorium, Th -232-5 230 -S Iodine, . . I 126-97 126-01 Thulium, Tm 171 169 7 Iridium, Ir 193 191-5 Tin, . Sn 119 118 1 Iron, . Fe 55-9 55-5 Titanium, Ti 48-1 47-7 Krypton, . Kr 81-8 81-2 Tungsten, . W 184 182-6 Lanthanum, . La 138-9 137-9 Uranium, TJ 238-5 236-7 Lead, . . Pb 206-9 205-35 Vanadium, V 51-2 50-8 Lithium, . Li 7-03 6-98 Xenon, . Xe 128 127 Magnesium, . Mg: 24-36 24-18 Ytterbium, . Yb 173 171-7 Manganese, . Mn 55 54-6 Yttrium, Yt 89 88-3 Mercury, . Hg 200 198-5 Zinc, . Zn 65-4 64-9 Molybdenum, . Mo 96 95-3 Zirconium, . Zr 90-6 89-9 38o SYNTHETIC DYESTUFFS. Acetic Acid. Acetic acid (botli the dilute acid, 30 to 40 per cent., and glacial acetic acid) is tested by titration with normal caustic soda solution using phenolphthalein as indicator. The specific gravity of acetic acid is shown in the following table (Roscoe) : — Sp. Gr. at 16°. Acetic Acid, per cent. Sp. Gr. at 15°. Acetic Acid, per cent. 0007 1 1-0746 75 0067 6 1-0748 80 014-2 10 1-0739 85 0214 15 1-0713 90 0284 20 1-0706 91 1 0350 25 1-0696 92 0412 30 1-0680 93 0470 35 1-0674 94 0523 40 1 -0660 95 0571 45 1-0644 96 0615 50 1-0625 97 0653 56 1-0604 98 0685 60 1-0580 99 0712 65 1-0663 100 1-0733 70 Table of Percentages of Hydpochlopic Acid. Specific Degree Degree Twaddell. Percentage Specific Degree Degree I'lTeeiitaije Gravity. Bauin^. HCL 0-016 Gravity. 1-105 Baum^. Twaddell. HCl. ' 1-000 0-0 13-6 21 20-97 005 0-7 1 0-15 1-110 14-2 22 21-92 010 1-4 2 2-14 1-115 14-9 23 22-86 015 2-1 3 3-12 1-120 15-4 24 23-82 020 2-7 4 4-13 1-126 16-0 25 24-78 026 3-4 5 5-15 1-130 16-5 26 •25-75 030 4-1 6 6-15 1-136 17-1 27 26-70 035 4-7 7 7-16 1-140 17-7 28 27-66 040 5-4 8 8-16 1-145 18-3 29 28-61 045 6-0 9 9-16 1-150 18-8 30 •29 -.17 050 6-7 10 10-17 1-155 19-3 31 30-56 055 7-4 11 11-18 1-160 19-8 32 31-52 060 8-0 12 12-19 1-165 20-3 33 32-49 065 8-7 13 13-19 1-170 20-9 34 33-46 070 9-4 14 14-17 1-176 21-4 35 34-42 075 10-0 15 15-16 1-180 22-0 36 36-39 080 10-6 16 16-16 1185 22-5 37 86-31 085 11-2 17 17-13 1-190 •23-0 38 37-23 090 11-9 18 18-11 1-195 •23-5 39 38-16 095 12-4 19 19-06 1-200 24-0 40 39-11 1-100 13-0 20 20-01 38i Table of Percentag-es of Nitric Acid at 15° Specific Degree Degree Twaddell. Percentage Specific Degree Degree Percentage Gravity. Baume. HNO3. Gravity. Baum^. T^vaddell. HNO3. 1-000 0-10 1-265 30-2 53 42-10 1-005 0-7 1 1-00 270 30-6 54 42-87 1-010 1-4 2 1-90 275 31-1 55 43-64 1-015 2-1 3 2-80 280 31-5 56 44-41 1-020 2-7 4 3-70 285 32-0 57 45-18 1-025 3-4 5 4-60 290 32-4 58 45-95 1-030 4-1 6 5-50 295 32-8 59 46-72 1-035 4-7 7 6-38 300 33 3 60 47-49 1-040 5-4 8 7-26 305 33-7 61 48-26 1-045 6-0 9 8-13 310 34-2 62 49-07 1-050 6-7 10 8-99 315 34-6 63 49-89 1-055 7-4 11 9-84 320 35-0 64 50-71 1-060 8-0 12 10-68 325 35-4 65 51-53 1-065 8-7 13 11-51 330 35-8 66 52-37 1-070 9-4 14 12-33 335 36-2 67 53-22 1-075 10-0 15 13-15 340 36-6 68 54-07 1-OSO 10-6 16 13-95 345 37-0 69 54-93 1-085 11-2 17 14-74 350 37-4 70 65-79 1-090 11-9 18 15-53 355 37-8 71 56-66 1-095 12-4 19 16-32 360 38-2 72 57-57 1-100 13-0 20 17-11 365 38-6 73 58-48 1105 13-6 21 17-89 370 39-0 74 59-39 1-110 14-2 22 18-67 375 39-4 75 60-30 1-115 14-9 23 . 19-45 380 39-8 76 61-27 1-120 15-4 24 20-23 385 40-1 77 62-24 1-125 16 25 21-00 390 40-5 78 63-23 1-130 16-5 26 21-77 395 40-8 79 64-25 1-135 17-1 27 22-54 400 41-2 80 65-30 1-140 17-7 28 '23-31 405 41-6 81 66-40 1-145 18-3 29 24-08 410 42-0 82 67-50 1-150 18-8 30 24-84 415 42-3 83 68-63 1-165 19-3 31 25-60 420 42-7 84 69-80 1-160 19-8 32 26-36 425 43-1 85 70-98 1-165 20-3 33 27-12 430 43-4 86 72-17 1-170 20-9 34 ■27-88 435 43-8 87 73-39 1-175 21-4 35 28-63 440 44-1 88 74-68 1-180 22-0 36 29-38 445 44-4 89 75-98 1185 -22-5 37 30-13 450 44-8 90 77-28 1-190 23-0 38 30-88 456 45-1 91 78-60 1-195 23-5 39 31-62 460 46-4 92 79-98 1-200 24-0 40 32-36 465 45-8 93 81-42 1 205 '24-5 41 33-09 470 46-1 94 82-90 1-210 25-0 42 33-82 475 46-4 95 84-45 1-215 25-5 43 34-55 480 46-8 96 86-05 1-220 26-0 44 35-28 485 47-1 97 87-70 1-225 26-4 45 36-03 490 47-4 98 89-60 1-230 26-9 46 36-78 495 47-8 99 91-60 1-235 27-4 47 37-53 500 48-1 100 94-09 1-240 27-9 48 38-29 505 48-4 101 96-39 1-245 28-4 49 39-05 .510 48-7 102 98-10 1-250 28-8 50 39-82 515 49-0 103 99-07 1-255 29-3 51 40-58 1-520 49-4 104 99-67 1-260 29-7 52 41-34 SYXTHETU; DYKSTUFFS. Table of Percentages of Caustic Soda (Sodium Hydrate). Specific Gravity. Degree Bamuu. Degree Twaddell. Percfiitage NaOH. 1-007 1 1-4 0-61 1-014 2 2-8 1-20 1-022 3 4-4 2-00 1-029 4 5-8 2-71 1-036 5 7-2 3-35 1-045 6 9-0 4-00 1 -052 7 10-4 4-26 1-060 8 12-0 5-29 1-067 9 13-4 5-87 1-075 10 15-0 6-55 1-083 11 16-6 7-31 1-091 12 18-2 8-00 1-100 13 •20-0 8-68 1-108 14 21-6 9-42 1-116 15 23-2 10-06 1-125 16 25-0 10-97 1-134 17 26-8 11-84 1-142 18 28-4 12-64 :-152 19 30-4 13-55 1-162 20 32-4 14-37 1-171 21 34-2 15-13 1-180 22 36 15-91 1-190 23 38 16-77 1-200 24 40-0 17-67 1-210 25 42-0 18-58 1-220 26 44-0 19-58 1-231 27 46-2 20-59 1-241 28 48-2 21-42 1-252 29 50-4 22-64 1-263 30 52-6 23-67 1-274 31 54-8 24-81 1-285 32 57-0 25-80 1-297 33 59-4 26-83 1-308 34 61-6 27-80 1-320 35 64-0 28-83 1-332 36 66-4 29-93 1-345 37 69-0 31-22 1-357 38 71-4 32-47 1-370 39 74-0 33-69 1-383 40 76-6 34-96 1-397 41 79-4 36-25 1-410 42 82-0 37-47 1-424 43 84-8 38 80 1-438 44 87-6 39-99 1-453 45 90-6 41-41 1-468 46 93-6 42-88 1-483 47 96-6 44-38 1-498 48 99-6 46-15 1-514 49 102-8 47-60 1-530 50 106-0 49-02 383 Table of Pepeentage of Sulphuric Acid {Lunge and isler). SpeciKc Gravity i. 15° Degree Percentage Specific Gravity 4. 15° Degree Perceutage at -TT. 4° Baume. H^O,. at ^. 4° Baume. H2SO,. 1-000 0-09 1-560 51-8 65-08 1-010 1-4 1-57 1-570 52-4 65-90 1-020 2-7 3-03 1-580 53-0 66-71 1-030 4-1 4-49 1-590 53-6 67-59 1-040 5-4 5-96 1-600 54-1 68-51 1-050 6-7 7-37 1-610 54-7 69-43 1-060 8-0 8-77 1-620 55-2 70-32 1-070 9-4 10-19 1-630 55-8 71-16 1-080 10-6 11-60 1-640 56-3 71-99 1090 11-9 12-99 1-650 56-9 72-82 1-100 13-0 14-35 1-660 57-4 73-64 1-110 14-2 15-71 1-670 67-9 74-51 1-120 15-4 17-01 1-680 58-4 75-42 1-130 16-5 18-31 1-690 58-9 76-30 1-140 17-7 19-61 1-700 69-5 77-17 1-150 18-8 20-91 1 710 60-0 78-04 1-160 19-8 22-19 1-720 60-4 78-92 1-170 20-9 23-47 1-730 60-9 79-80 1-180 22-0 24-76 1-740 61-4 80-68 1-190 23-0 26-04 1-750 61-8 81-56 1-200 24-0 27-32 1-760 62-3 82-44 1-210 25-0 28-58 1-770 62-8 83-32 1-220 26-0 29-84 1-780 63-2 84-50 1-230 26-9 31-11 1-790 63-7 85-70 1-240 27-9 32-28 1-800 64-2 86-90 1-250 28-8 33-43 1-810 64-6 88-30 1-260 29-7 34-57 1-820 65-0 90-05 1-270 30-6 35-71 1-821 90-20 1-280 31-5 36-87 1-822 65-1 90-40 1-290 32-4 38-03 1-823 90-60 1-300 33-3 39-19 1-824 65-2 90-80 1 310 34-2 40-35 1-825 91-00 1-320 35-0 41-50 1-826 65-'3 91-25 1-330 35-8 42-66 1-827 91-50 1-340 36-6 43-74 1-828 65-4 91-70 1-350 37-4 44-82 1-829 91-90 1-360 38-2 45-88 1-830 92-10 1-370 39-0 46-94 1-831 65-5 92-30 1-380 39-8 48-00 1-832 92-52 1-390 40-5 49-06 1-833 65-6 92-75 1-400 41-2 50-11 1-834 93-05 1-410 42-0 51-15 1-835 65-7 93-43 1-420 42-7 52-15 1-836 93-80 1-430 43-4 53-11 1-337 94-20 1-440 44-1 54-07 1-838 65-8 94-60 1-450 44-8 65-03 1-839 95-00 1-460 45-4 55-97 1-840 65-9 95-60 1-470 46-1 56-90 1-8405 95-95 1-480 46-8 57-83 1-8410 97-00 1-490 47-4 58-74 1-8415 97-70 1-500 48-1 59-70 1-8410 98-20 1-510 48-7 60-65 1-8405 98-70 1-620 49-4 61-59 1 -8400 99-20 1-530 50-0 62-53 1-8395 99-45 1-540 50-6 63-43 1-8390 99-70 1-550 51-2 64-26 1-8385 99-95 3H SYNTHF.TIC DYESTtlFFS. Table of Percentage of Aqueous Ammonia Solution at 15° (LiDii/i' and W'ieniir/;). The numbers given in the tliinl column are corrections to be applierl for the interval of temperature 13° to 17°. If, for example, the specific gravity has been found to be 0-900 at 13°, the value at 15° is found by subtracting 2x0-00057 = 0-001 from this number (0-900). One obtains the value 0-899, and therefore the percentage of annnnnia is J per cent, higher. Specific Gravity. 1-000 Percentage NH3. 0-00 Correction for ± 1°. Specific Gravity. Percentage Correction for ± 1°. 0-00018 0-940 15-63 0- 00039 0-998 0-45 0-00018 0-938 16-22 0- 00040 0-996 0-91 0-00019 0-936 16-82 0- 00041 0-994 1-37 0-00019 0-934 17-42 0- 00041 0-992 1-84 0-00020 0-932 IS -03 0- 00042 0-990 2-31 0-00020 0-930 18-64 0- 00042 0-988 2-80 0-00021 0-928 19-25 0- 00043 0-986 3-30 0-00022 0-926 19-87 0- 00044 0-984 3-80 0-00022 0-924 20-49 0- 00045 0-982 4-30 0-00022 0-922 21 -12 00046 0-980 4-80 0-00023 0-920 21-75 00047 0-978 5-30 0-000-23 0-918 22-39 00048 0-976 5-80 0-000-24 0-916 23-03 00049 0-974 6-30 0-00024 0-914 23-68 00050 0-972 6-80 0-0002.'-. 0-912 24-33 00051 0-970 7-31 -0002fi 0-910 24-99 00052 0-968 7-82 0-00026 0-908 25-65 00053 0-966 8-33 000-26 0-906 26-31 00054 0-964 8-84 0-00027 0-904 26-98 00055 0-962 9-35 -0002s 0-902 •27-65 00056 0-960 9-91 0-000-29 0-900 28-33 00057 0-958 10-47 0-00030 0-898 29-01 00058 0-956 11-03 0-00031 0-896 29-69 00059 0-954 11-60 0-00032 0-894 30-37 00060 0-952 12-17 0-00033 0-892 31-05 00060 0-950 12-74 0-00034 0-890 31 -75 00061 0-948 13-31 0-0003.^ 0-888 32-50 -00062 0-946 13-88 0-00036 0-886 33-25 •00063 0-944 14-46 0-000:i7 0-884 3410 (1 00064 0-942 15-04 0-00038 0-882 1 34-95 0-00065 APPENDIX. 385 Specific Gravity of Solutions of Tannic Acid at 15° (Trammer). Specific Percentage Specific Percentage Specific Percentage Gravity. Tannic Acid. Gravity. Tannic Acid. Gravity. Tannic Acid. 1-0040 1-0 1-0092 2-3 1-0144 3-6 1 -0044 1 1-0096 2-4 1-0148 3-7 1-0048 2 1-0100 2-5 10152 3-8 1-0052 3 1-0104 2-6 1-0160 40 1-0056 4 1-0108 2-7 1-0164 4-1 1-0060 5 1-0112 2-S 1-0168 4-2 1-0064 6 1-0116 2-9 1-0172 4-3 1-0068 7 1-0120 3-0 1-0180 4-5 1-0072 8 1-0124 . 3-1 1-0184 4 6 1-0076 9 1-0128 3-2 10188 4-7 1-0080 2 1-0132 3-3 1-0192 4-8 1-00S4 2 1 1-0136 3 4 1-0196 4-9 1-0088 2-2 1-0140 3-5 1-0200 5-0 1-0242 6 1-0489 12 1-0740 18 1-0324 8 1 -0572 14 1 -0824 20 1-0406 10 1-0656 16 Specific Gravity of Solutions of Sodium Carbonate at 15° (Lunge). Percentage by Weight. Specific Gravity. Degrees Baume. Degrees Twaddell. 1 Na^COj. NajCOs + lOAq. 1-007 1 1-4 0-67 1-807 014 2 2 8 1-33 3-587 022 3 4 4 2 09 5-637 029 4 5 8 2-76 7-444 036 5 7 2 3-43 9-251 045 6 9 4-29 11-570 052 / 10 4 4-94 13-323 060 8 12 5-71 15-400 067 9 13 4 6-37 17-180 075 10 15 7-12 19-203 083 U 16 6 7-88 21-252 091 12 18 2 8-62 23-248 100 13 20 9-43 25-432 108 14 21 6 10 19 27-482 116 15 23 2 10-95 29 -532 125 16 25 11-81 31-851 134 17 26 8 12-61 34-009 142 18 28 4 13-16 35-493 1-152 19 30-4 14-24 38-405 25 386 SYNTHETIC DYESTUFFS. Specific Gravity of Solutions of Common Salt at 15* (Gerlach) specific Percentage S|)ecilic Percentage. Specific Percentage Gravity. NaCl. Gravity. NaCl. Gravity. NaCL 1-00725 1 1 07335 10 1-14315 19 1 -01450 2 1-08097 11 1-15107 20 1-02174 3 1-08859 12 1-15981 21 1 -02899 1 4 1-09622 13 1-16755 22 1 -03624 5 1-10384 14 1-17580 23 1-04366 I 6 1-11146 15 1-18404 24 1-05108 7 1-11938 16 1-19228 25 1 -05851 8 1-1-2730 17 1 -20098 26 1 06593 9 1-13523 18 1 -20438 26-395 Specific Gravity of Solutions of Sodium Sulphate (Glauber's Salt) at 19° (Schiff). Specific Percentage Percentage Specific Percentage Percentage Gravity. N&.SO, + lOAq. NaJSO,. Gravity. NaJSO, + 10Aq. 16 NaJSO,. 1 0040 1 0-441 1-0642 7-056 0079 2 0-881 1-0683 17 7-497 0118 3 1-323 1-0725 18 7-938 0158 4 1-764 1-0766 19 8-879 0198 5 2-205 1-0807 20 8-820 0238 6 2-645 1 -0849 21 9-261 0278 7 3-087 1-0890 22 9-702 0318 8 3-528 1-0931 23 10-148 0358 9 3-969 1 0973 24 10-584 0398 10 4-410 1-1015 25 11-025 0439 11 4-851 1-1057 26 11-466 0479 12 5-292 1-1100 27 11-907 0520 13 5-373 1-1142 28 12-348 0560 14 6-174 1-1184 29 12-789 1 -0601 15 6-615 1-1226 30 13-230 Specific Gravity of Solutions of Sodium Bisulphite at 15° .Si)ecilic Gravity. Percentage NaHSO 1-008 1-6 1022 2-1 1-038 3-6 1-052 5-1 1-068 6-5 1-084 8-0 1-100 9-5 1-116 11-2 1-134 12-8 1-152 14-6 1-171 16-5 1-190 18-5 1-210 •20-9 1 "230 23-5 1-252 25-9 1-275 28-9 1-298 31-7 1-321 84-7 1-345 38 Percentage S0„. 0-4 1-8 2-2 3-1 3-9 6-8 7-8 9-0 10-2 11-5 12-9 14-5 15-9 17-8 196 22-5 23-6 APPENDIX. 387 Specific Gravity of Solutions of Sodium Acetate at 17*5° {Gerlach). Specific Gravity. Percentafre CHsCOONa. Percentage CHsCOONa + SHoO. 1-015 3-015 5 031 6-030 10 047 9-045 15 063 12-060 20 0795 15075 25 096 18-090 30 113 21-105 35 1305 24-120 40 1485 27-135 45 ^ 1670 30-150 50 Specific Gravity of Solutions of Chloride of Lime at 15° Specific Gravity. Grams active Chlorine per litre. 1-105 64 097 60 087 55 078 50 069 45 060 40 053 35 045 30 037 25 030 20 023 15 015 10 1-008 a Specific Gravity of Solutions of Sulphate of Alumina at 15° Specific Gravity. Percentage Al,{SOj3. Specific Gravity. Percentage A.USO,),. 1-0170 1 1-1467 14 0270 2 1-1574 15 0370 3 1-1668 16 0470 4 1-1770 17 0569 5 1-1876 18 0670 6 1-1971 19 0768 7 1-2074 20 0870 8 1-2168 21 0968 9 1-2274 22 1071 10 1-2375 23 1171 11 1 -2473 24 1270 12 1-2573 25 1-1369 13 388 SYNTHETIC DYESTUFFS. Specific Gravity of Solutions of Acetate of Alumina at 17 Specific Gravity. 1-100 Grams AL,0, per litre. 40-8 1-098 40 1-086 35 1-074 30 1-062 26 1-050 20 1-038 15 1025 10 1-012 S Specific Gravity of Solutions of Tartar Emetic at 17'5° (Streit). Specific Gravity. Percentage Tartar Emetic. Specific Gravity. Percentage Tartar Emetic. Specific Percentage Gravity. Tartar Emetic. 1-005 1-007 1-009 1-012 0-5 1-0 1-5 2-l» 1-015 1-018 1-022 1-027 2-5 3-0 3-5 4-0 1-031 4-5 1-035 5-0 1-038 1 6-5 1-044 6-0 Specific Gravity of Solutions of Copper Sulphate at 17 Specific Gravity. Percentage CUSO4-1-5H2O. 4 6 8 10 12 Specific Gravity. Percentage CUSO4 + 5H0O. 1-0126 1-0254 1 0384 1-0516 1-0649 1-0785 1 -0933 1-1063 1-1208 1-1354 1-1501 1-1659 14 16 18 20 24 APPENDIX. 389 Specific Gravity of Solutions of Cliromium Acetate at 17°. Specific Gravity. Grams Cr.,0, per litre. 5 Specific Gravity. Grams CroOj per litre. 1-007 1-084 60 014 10 091 65 021 15 098 70 028 20 105 75 035 25 112 80 042 30 119 85 049 35 126 90 056 40 133 95 063 45 140 100 070 50 147 105 1-077 55 1-151 107 Specific Gravity of Solutions of Pyrolig-nite of Iron (Iron Acetate) at 18°. Specific Gravity. 'pTii!:i?°^ «p-ifi Gravity. Grams FeoOj per litrer 274 190 1 137 95 266 185 1 130 90 258 180 1 123 85 250 175 1 116 80 242 170 1 109 75 235 165 1 102 70 228 160 1 095 65 221 155 1 088 60 214 150 1 081 55 207 145 j 1 074 50 200 140 1 1 067 45 193 135 t 1 060 40 186 130 1 053 35 179 125 1 046 30 172 120 1 039 25 165 115 1 032 20 158 110 1 1 025 15 151 105 , 1 018 10 1-144 100 1 010 5 Specific Gravity of Solutions of Ferrous Sulphate at 15° Specific Gravity. Percentage reSOj + 7H20. Specific Gravity. Percentage 1-011 1-021 1-032 1-043 1-054 1-065 2 4 6 8 10 12 1-082 1-112 1-143 11 74 1-206 1-239 15 20 25 30 35 40 390 SYNTHKTIC DYESTUFFS. Comparative Hydrometer Scale, Sp. Gr., Twaddell, and Baum6. at 12-5° C. Twaddell. Baume. Specific Gravity. Twaddell. Baume. | t Specific Gravity. 1-270 1-000 54 30-6 1 0-7 1-005 55 31-1 1 -275 2 1-4 1-010 56 31-5 1 -280 3 2-1 1-015 67 32-0 1-285 4 2-7 i 1020 58 32-4 1-290 5 3-4 1-0-25 59 32-8 1-295 6 4-1 1-030 60 33 -3 1 -300 7 4-7 1-035 61 33-7 1 -305 8 5-4 1-040 ' 62 34 2 1-310 9 6-0 1-045 63 34-6 1-315 10 6-7 1050 64 35-0 1-3-20 11 7-4 1-055 65 35-4 1-3-25 12 8-0 1-060 66 35-8 1-330 13 8-7 1-065 67 36-2 1 335 14 9-4 1-070 68 36-6 1-340 15 10-0 1-075 69 37-0 1-345 16 10-6 1-080 70 37-4 1-350 17 11-2 1-085 71 37-8 1 -355 18 11-9 1-090 72 38-2 1-360 19 12-4 1-095 73 38-6 1-365 20 13-0 1-100 74 89-0 1-370 21 13-6 1-105 75 39-4 1-375 22 14-2 1-110 76 39-8 1-380 1 23 14-9 1-115 77 40-1 1-385 24 15-4 1-120 78 40-5 1-890 25 16-0 1-125 79 40-8 1-395 26 16-5 1-130 80 41-2 1-400 27 17-1 1-135 81 41-6 1-405 28 17-7 1-140 82 42-0 1-410 29 18-3 1-145 83 42-3 1-415 30 18-8 1-150 84 42-7 1-420 31 19-3 1-155 85 43-1 1-425 32 19-8 1-160 86 43-4 1-430 33 20-3 1-1. !0 87 43-8 1-435 34 20-9 1-1 70 88 44-1 1-440 35 21-4 1-1 75 89 44-4 1-445 36 22-0 1-180 90 44-8 1-450 37 22-5 1-185 91 45-1 1-455 38 23-0 1-190 92 45-4 1-460 39 23-5 1-195 93 45-8 1-465 40 24-0 1-200 94 46-1 1-470 41 24-5 1-205 95 46-4 1-475 42 25-0 1-210 96 46-8 1-480 43 25-5 1-215 97 47-1 1-4S5 44 26 1-220 98 47-4 1-490 45 26-4 1-225 99 47-8 1-495 46 26-9 1-230 100 48-1 1 -500 47 27-4 1 -235 101 48-4 1 -505 48 27-9 1-240 102 48-7 1-510 49 28-4 1-245 103 49-0 1-515 50 28-8 1-250 104 49-4 1 -520 51 29-3 1-255 105 49-7 1 -525 ^•2 29-7 1-260 106 50-0 1 r.30 53 30-2 1-265 To convert degrees Tw. into sp. gr-, multiply by 5, add 1000, and dinde by 1000. EREATA AND ADDENDA. To page 66. Lithol red R [B] is e-naiihthylamiue-l-sulphonic acid + /3-naphthol. Of the various brands of Heliopurpurines which are used exteusively for making lakes, the conibiualion of ;8-naphthyIamine-l : 6-disulphonic acid + j8-naphthol disulphonic acid R gives a bluish-red lake. 3-naphthylamine-3 : 6-disulphonic acid + j8-naphthol-3 : 6 : 8-trisulphonic acid gives a yellowish-red lake. (8-naphthylamiue-3 : 6-disulphonic acid-l-a-naphthol-3 : 6-disulphonic acid gives a red lake. Line 10. For Azocochenille read Azocochineal. To pac/c 67. Anthracene acid brown B [C] is Nitroamidosalicylic acid^ /■m-phenyleuediamine. a-naphthylamine ^ To paye 71. Wool red G [B] is ,phenol-o-sulphonic acid. Benzidine'(' amidonaphthol sulphonic acid y (in acid solution). Pages 88 and 89. For New fuchsin read New magenta. To page 120. Alizarine irisol has the constitution ro OH II II ^" NH.C„Hj.SO,H Anthraquinone green GX ^" NHC„H, Alizarine pure blue ro ^^^ /\/°°\^Br II \ r NH.C6HJ.S03H To page 219. For the preparation of Neville & Winther's acid by the bisulphite method, seeE.P. 16,807«'. INDEX. Absorption theory of dyeing, 32. Acetanilitle, nitration of, 23. preparation of, 201. Acetate of alumina, specific gravity of, 388. iron, sjireific gravity of, 389. Acetic acid, strength of, 380. Acetyl-/)-phenylenediamine, 20. 7 Acid, 17. f Acid, 15. Acid alizarine blue GR, 123. BB, 123. reactions of, 336. blue 6G, 81. dyestutfs, 35. dyeing of, 289. reactions of, 347, 348. green, 80. reactions of, 326. magenta, 92. reactions of, 326. rosamine, 102. violet N, reactions of, 327. violets, 92. yellow, 63. Acridine, 112. dyestuifs from, 112. orange, 113. R extra, 113. red, 98. yellow, 113. Atijective dyes, 35. Aldehydes, 31. Aldiraides, 31. Alizarine, 115. derivatives of, 119. [ireparation of, 225. reactions of, 334. on the fibre, 356. GD, 122. R.\, 122. rcd.S, 120. S.'^, 122. SSS, 121. SX extra, 122. black P, 122. reactions of, 336. S, 114. Alizarine blue, 120. reactions of, 335. acid BB and GR, 123. S, 120. Bordeaux B, 122. cardinal, 119. Alizarine cyanine R, 123. garnet, 119. green B, 131. G, 131. S [B], 122. S [M], 120. reactions of, 335. indigo blueS, 123. irisol, 391. isomerides of, 120. lakes of, 119. maroon, 119. orange G, 121. reactions of, 334. pure blue, 391. yellow, 64. A, 114. preparation of, 254. C, 114. GG, 65. FB, 73. R, 65. Alkali blue, 92. preparation of, 248. violet, 93. Alsace green J. See Gambin G or Y. Alumina mordants, 292. Amaranth. .See Fast red D. Amethyst violet, 143. ^)-Araidoacetanilide, 20. prejiaration of 203. a-Amidoalizarine, 119. )3-Amidoalizarine, 119. Amidoazobenzene, discovery of, 61. from diazoamidobenzene, 52. Indulines from, 143. reduction of, 53. with concentrated sulphuric acid, 53. Amidoazo-compounds, 62. discovery of, 61. formation of, 47. laws regulating formation of, 49. mode of formation of dyestuifs from, 146. Amidoazotoluene, 1 9. preparation of, 260. y-Amidobenzaldehyde, 83. Amidobenzene. See An Huh: p-Amidobenzyl alcohol, 87. Aniido-compounda (benzene series), 19. (naphthalene series), 24. Amido-group, as auxochrorae, 38. reactions of, 21. when not diazotisable. 49. jyo Amido-G acid, 14. o-Amidoinande!ic acid, 159. 1 : 8-Amidonaphthol-3 : 6-disulphonic acid (H acid), 17. preparation of, 220. 1 : 8-Amidonaphthol-2 : 4-disulphonicacid, 17. 2 ; S-Amidonaphthol-3 : 6 -disulphonic acid, 1 7. Amidonaphthol sulphonio acids, analysis of, 281. combination of, -with diazo-salts, 51. 1 : 8-Araidonaphthol-4-sulphonic acid, 16. 2 : S-Amidonaphthol-6-sulphonic acid (y acid), 17. combination of, with diazo-salts, 48. preparation of, 222. Amidophenols, formation of, 27. p-Amidophenol, sulphur colours from, 167. o-Amidophenylacetic acid, 159. Amido-R acid, 14. Ammonia, strength of, 384. Ammoniacal liquor, 4. Ammonium base of rosaniline, 86. Analysis of dyestutfs, 341. Anh3'droformaldehydeaniline, 88. Aniline, 19. analysis of, 271. diazotisation of, 226. oxidation of, 82. preparation of, 200. Aniline black, 37, 149. production on the fibre, 295. reactions of, on the fibre, 356, 358. blue (spirit soluble), preparation of, 246. oil for blue. 90. for red, 89. analysis of, 272. salt, analysis of, 272. sulphonic acid of, 23. yellow, first manufactured, 61. Anthracene, analysis of, 281. in heavy oil, 3. oxidation of, 3. purification of, 3. Anthracene acid brown B, 391. blue WK, 123. brown, 121. dyestufi's, reactions of, on the fibre, 356. oil, 3. Anthracite black S, 68. Anthrapurpurine, 117. Anthraquinone sulphonic acid, 117. preparation of, 224. Anthraquinone, 116. green GX, 391. disulphonic acid, 117. preparation of, 223. Anthrarufine, 121. Application of the dyestuffs, 32. Apigenine, 172. Apiine, 172. Aposafranines, constitution and history of, 134. Aposafranole, 138. Arsenic acid as oxidising agent, 82. Atlas red, 63. Atomic weights, 379. Auramine G, 78. 0,77. Auramine 0, preparation of, 241. reactions of, 323. Auramine hydrochloride, formula of, 77. Aurantia, 45. Aurine, 93. Auxochrome, 38. Azaline, 154. Azarine S, reactions of, 317. Azine green GB, 140. S, 141. group, 132. scarlet G, 340. Azobenzene, with concentrated sulphuric acid. 53. Azo blue, 71. reactions of, 346. Azocarmine B. 140. G, 139. base, 146. Azococcine 2R, 65. Azocochineal, 66. Azo-compounds, abnormalities, 52. action of concentrated sulphuric acid on, 53. as mordant dyestuBs, 55. colour of, 55. colours with sulphuric acid, 53. constitution of, 53. disazo-, 66. division of, 62. formation of, 47. from tetrazo-salts, 69. historical, 61. hydrazone form of, 54. internal formation of, 53. laws regularing formation of, 49. monazo-, 62. reduction of, 53. substantive to cotton, 57. tetrakisazo, 74, Azo-dyestuffs, analysis of, 300. with ritanous chloride, 302. reactions of, 346. Azoeosine, 66. Azofuchsine B, 65. G, 66. Azo green, 55, 81. Azonaphthalenes, with sulphuric acid, 53. Azo orange, 74. Azophor blue, 49. red, 49. Azorubine, 66. Azo.xy-dyestuffs, 45. Baking process, 9. Bases, in heavy oil, 3. not yielding substantive cotton dyes, 59. used for substantive cotton dyes, 58. yielding rosanilines on oxidation, 85. yielding safranines on oxidation, 141. Basic dvestuffs, 35. dyeing of, 289. reactions of, 347, 348. reactions of, on the fibre, 357, 358. Basle blue R, 140. S, 141. Benzal chloride, preparation of, 210. Benzaldehyde, 31. 394 INDEX. Benzaldehyde, analysis of, 279. preiiaration of, 210. Benzene, amido-derivatives of, 19. analysis of, 270. dianiido-derivatives of, 20. from acetylene, 2. from coke ovens, 3. from methane, 2. hydroxyl derivatives of, 27. in coal-tar, 1. in light oil, 3. purification of, 3. sulphonation of, 9. yearly output of, 3. Benzene diazonium chloride, 26. Benzene- «i-disulphonic acid, 27. Benzene sulphonic acid, 27. Benzidine, 20. analysis of, 27S. diazotisation of, 231. horaologues of, 57. preparation of, 208. Benziiiine-TO-disulphonie acid, 59. Benzidincsulphone, 59. Benzoazurine G, 71. Benzo black blue G, 73. 5G, 73. R, 73. brown B, 74. G, 74. fast pink, 71. Benzotlavine, 112, 113. preparation of, 253. Benzo grey, 72. Benzoic acid, 29. analysis of, 279. Benzo indigo blue, 72. Benzonitrile, hydrolysis of, 29. Benzo olive, 73. Benzopurpurine B, 71. reactions of, 321. 4B, 70. analysis of, 304. preparation of, 231. lOB, 71. Benzo sky blue, preparation of, 234. violet K, 71. Benzyl chloride, 31. Benzylideneaniline, nitration of, 23. Biebrich scarlet, 68. discovery of, 62. reactions of, 319. Bindschedler's green, 132. Bisniarck brown, 20, 72. discover}' of, 61. reactions of, 322. Black, Alizarine, P, 122. reactions of, 336. S, 114, 122. Aniline, 149, 295. reactions of, on the fibre, 356, 358. Anthracite, B, 68. Columbia, KB, 73. R, 72. Diamine, BH, 71. RO, 70. preparation of, 235. Black, Diamine, RO, reactions of, 322. Diaminogen (for cotton), 69. Diamond, 69. dyeslutfs, reactions of, on the fibre, 362. Fast, 131, 167. Katigene, 167. Naphthol, B, 68. prejiaratiou of, 237. 6B, 69. Na])hthylaraine, D, 69. Pyrogene, 167. Pyrrol, 167. Immedial, 167. Isodiplienyl, preparation of, 239. Suljihanil! 167. Sulphur, T, 167. preparation of, 265. Thionol 167. Vidal, 167. Wool, 6B, 67. Black blue, Benzo, R, 73. G, 73. 5G, 73. Blue, Azo, 71. reactions of, on the fibre, 357. Acid, 6G. SI. Alizarine, BB, reactions of, 336. Alizaiine, 120. pure, 391. reactions of, 335. S, 120. Alkali, 92. preparation of, 248. Aniline (spirit soluble), preiiaration of, 246. Anthracene, WR, 123. Basle, R, 140. S, 141. Benzo skj-, pre}iaration of, 234. Brilliant alizarine. GR, 129. Capri. GX, 129. Chicago, 6B, 71. Chrome, 91. Cotton, 82. R. 129. Dclphin, 130. Diphenylamine, 91. dyestufis, reactions of, on the fibre, 353, 362. Fast, 129. acid, R, 102. reactions of, 329. Gallamine, 130. Glacier, 82. Hiichst new, 93. Immedial, 167. Indoine, R, 66, 167. Iris, 130. Lanacyl, BE, 66. Lyons, 90. Melanogen, 167. Sleldola's, 129. prejiaration of, 257. reactions of, 337. Meta])henylene, B, 144. Slethyl alkali, reactions of, 328. Methylene, B, 127. analysis of, 305. preparation of, 258. INDEX. 395 Blue, Methylene, B, reactions of, 337. on the fibre, 357. Milling, 141. Naphthazine, 144. Naphthol. See Mc/dola's blue. Najihthyl, 141, 143. Navy, 92. Neutral, 140. New, R, 129. New methylene, N, 129. GG, 130. Nicholson's, 92. Night, 91. Nile, A, 130. 2B, 130. Opal, preparation of, 246. Patent, A, 81. V, reactions of, 327. Phenylene, 131. Pyrogene, 167. Rosaniline, 90. Soluble, preparation of, 249. reactions of, 328. Thiogene, 167. Thionine, G, 128. Toluidine, 0, 128. reactions of, 338. Toluvlene. 132. Victoria, B, 91. R, 91. 4R, 91. Water, 92. Blue black, Naphthol, 67. preparation of, 236. Naphthyl, N, 69. Books on dvestuffs, 180. ■ Bordeaux B"X, 68. discovery of, 61. Alizarine, B, 122. Brilliant alizarine blue GR, 129. Congo, 70. crocein, 68. reactions of, 320. green, 79. reactions of, 323. orange R, 66. Bronner's acid, 12. Bronze, Diamine, G, 72. Brown, Anthracene, 121. acid, B, 391. Benzo, B, 74. G, 74. Bismarck, 72. reactions of, 322. Congo, G, 73. R, 73. Diamine, M, 71. Direct, J, 74. dyestuti's, reactions of, on the fibre, 354, 378. Fast, G, 67. Hessian, BB, 74. MM, 75. Kyrogene, 167. Metachrome, B, 63. Naphthylaniine, 66. Resorcin, 67. Brown, Sudan, 66. Toluylene, 75. Caohou de Laval, 167. Camphoride, 170. Capri blue GN, 129. Carbazol yellow, 71. Carbinol base of rosaniline, 85. Carbolic acid. See Phenol. Carbonic acid used in phenol extraction, 4. Carboxyl compounds, 29. group, reactions of, 29. Cardinal, Alizarine, 119. Caustic soda, strength of, 382. Chemical theory of dyeing, 32. Chicago blue 6B, 71. Chloramine yellow, 133. Chloranil, 115. Chloranilic acid, 115. Chloride of lime, specific gravity of, 387. p-Chloronitrobenzene, 20. o-Chloronitrobenzene, alkaline reduction of, 21. Chloroxynaphthalinic acid, 115. Chloroxynaphthoquinone, 115. Chromin G, 153. Chrome blue, 91. colours, 91 green, 91. mordants, 294. violet (Bayer), 91. (Geigy), 95. yellow D, 66. Chromium acetate, specific gravity of, 389. Chromogen, 38. Chromone, 172. Chromophore, 38. Chromotrope 2B, 65. 6B, 65. 8B, 66. lOB, 66. reactions of, 316. 2R, 65. reactions of, 316. Chrysamine G, 70. preparation of, 230. Chrysaniline, 112. Chrysine, 169. Chrysoidine R, 63. discovery of, 61. preparation of, 226. reactions of, 315. Chrysoidine law, 49. exceptions to, 49. Chrysoine, 66. Chrysoline, 103. Chrysophenine, 72. Cleve's acids, 14. Claret, Union fast, 68. Classification of dyestuffs, 34. Cloth red B [0], 68. reactions of, 319. 3B, 68. G, 68. scarlet, 68. Coal-tar, occurrence and purification, 1. percentages from 100 tons, 4. yield from one ton, 4. 396 INDEX. Coal-tar tractions, purificatioii of, 3. Coccine, New, 66. Cochineal scarlet 2R, 65. Coeruleine, 107. reactions of, 333. S, 107. Coke ovens, used in producing benzene and toluene, 3. Colour of azocompounds, influence of groups on, 55. of trijihenjhucttiane dyestuffs, 95. Colours, ingrain, 36. Columbia black FB, 73. R, 72. discovery of, 62. green. 73. Compounds present in coal-tar, 4. Commercial xylene, 3. Congo, Brilliant, 70. brown Ci, 73. R, 73. Corinth, 70. red, 58, 70. analysis of, 301. discovery of, 62. reactions of, 321 on the fibre, 357 Conditions of formation of substantive cotton dyes, 61. Constitution of Alizarine, 117. azo-compounds, 53. diazo-salts, 25. the Pyronines, 107. the Rosaniline dyestufi's, 85. the Safranines and Aposafrauines, 134. Conversion of ITH., into OH, 194. Copper sulphate, specific gravity of, 388. Corallin, red and yellow, 94. Ooreine RR, 130. Cotton, basic dycstulfs on, 35. developed dyes on, 37. mordant dyestutl's on, 36. substantive cotton dyes on, 35. vat dyes on, 36. Cotton l)lue, 92. R, 129. dyeing, 286. orange R, 67. c;, 63. yellow G, 70. R, 66. Creosote oils, 4. Crocein 3B, 63. acid, 16. brilliant, 68. scarlet 8B, 68. scarlet extra, 68. Crystal I'onceau, 64. scarlet 6R, analysis of, 303. violet, 89. reactions of, 325. Crurapsall yellow, 66. Curcumine S, 46. Cyanine, Alizarine, R, 123. or Quinoline blue, 154. Cyanol, 81. extra, 81. Cyanosine spirit, 105. Cyanotriamidotriphenylmethane, 87. Cyclamine, 105. I)ahl'.s No. hi. acid, 14. Uelphin blue, 130. Derivatives of Alizarine, 119. I)evelo|)ed dyes, 37. Uialkyl-m-aniidophenols, 27. Dianiidoazobenzene. 59. Diamidocarbazol, 59. Diamido-derivatives of diphenyl, 20. ;jl)iamidodibenzyl, 60. Diamidodihydrodiniethylphenylacridine, 113. m-Dianiidodiphenic acid, 59. Diamidodiphenylamine, 60. /I- Dianiidodiiihenyl methane, 60. Diamidodiphenylurea, 60. Diamidotluorene, 59. 1 : 4-Diamidonaphthalone, 60. 1 : 5-Diamidouaphthalene, 60. 1:5- Diamidonaphthalene -3:7- disulphonic acid, 60. 1 : 4-I)iaraidonaplitlialene-6-sulphonic acid, 18. Diamidona]>lithalene sul|>honic acids, combina- tion of, with diazo-salts, 51. Diamidonaplitlialenes, combination of, with diazo-salts, 51. Diamidostilbene, 60. Dianiidostilbene disulphonic acid, 60. Diamidotriphenylmethanc, formation of, 83. Diamine black BH, 71. RO. 70. discovery of, 62. preparation of, 235. reactions of, 322. bronze G, 72. brown M, 71. fast red F, 70. prejiaration of, 232 green B, 73. discovery of, 62. sky blue, 71. violet N, formation of, 236. Diamines (benzene series), 20. )/i-l>iamines, \ise of. 20. Diaminogen black, for cotton, 69. dyes, IS. Diamond black, 69. tlavine, 66. fuchsin. See Diamond magenta. green, 69. magenta, 89. yellow O, 65, 66. R, 66. Oianisidine, 21, 58. analysis of, 278. diazotisation of, 234. I'-Dianisidine, diazo-salt of, 48. Diazoamidobenzene, 52. Diazoamidocompounds, formation of, 52. Diazol>enzene chloriile, 277. fornmla of, 25. Diazo-compound of naphthionic acid, 13. nn/t'-Diazoeyanide, 26. iyn-Diazocyanidc, 26. 397 Diazonaphthionic acid, stability of, 48. Diazonium cyanide, 26. theory of diazo-salts, 26. ait^i-Diazo-oxide, 25. sj/n-Diazo-oxide, 25. Diazo-salt of p-uitraiiiline, 43. solution, preparation of, 48. Diazo-salts, combination of, with naphthols, naphthylamiiies, and their sulphonic acids, 50. combination of, with dioxy- and diamido- naphthalenes, 51. constitution of, 25. diazonium theory of, 26. formation of, 22. preparation of, 24. reactions of, 23. reduction of, 25. stability of, 48. Diazosulphanilie acid, abnormal behaviour with aniline, 52. Diazosulphonic acids, stability of, 48. Diazooxy-compounds, formation of, 52. o-Dibromobeuzidine, 58. Dibromodihydroxybenzoylbenzoic acid, 103. a-;8-Dibromo-j8-o-nitrophenylpropionic acid, 157. Dibromoxanthopurpuriup, 104. Dichlorobenzidine, 21. m-Dichlorobenzidine, 59. o-Dichlorobenzidine, 58. Di-j9-diamidodiphenyl. See Benzidine. Di-p-diamidoditolyl. See Tolidiiie. Di-^-dioxybenzophenone, 83. Diethyl-)»-amidophenol, preparation of, 205. Diethylaniline, analysis of, 275. Dihydrodiamidodimethylplienylacridine, pre- paration of, 253. )«-Dihydroxybenzene, 27. Dihydroxytriphenylniethane, 83. Dioxin, 43. Dioxindol, 156. Dioxyanthraquinone, 115. Dioxy-compounds, combination of, with diazo- salts, 48. Dioxydichloroquinone, 115. Dioxydiphenylraethane, 94. 2 : 7-Dioxynaphthalene, 16. Dioxynaphthalenes, combination of, with diazo-salts, 60. Dioxynaphthalene sulphonic acids, combina- tion of, with diazo-salts, 51. Dioxytartaric acid, 76. Dimethylamidobenzoyl chloride, 30. Diniethylaniline, 23. action of formaldehyde on, 31. phosgene on, 30. analysis of, 274. preparation of, 204. si/m-Dimethyldiamido-di-o-tolylmethane, 78. 7(i-Dinitrobenzene, 6. analysis of, 271.- reduction of, 23. ??i-Dinitrophenol, preparation of, 211. Di-o-nitrophenyldiacetylene, 158. Dinitrosoresorcin. See Solid green. ?)i-Dinitrotoluene, analysis of, 271. 7)i-Diuitrotoluene, preparation of, 206. Diphenetidine, 58. Diphenyl, derivatives of, 57. diamines of, 20. Diphenylamine blue, 91. derivatives of, 23. dyestutt's, 124. sulphur colours from, 167. Direct brown, 74. dyes, 35. yellow, 46. Disazo-dyestulfs, 66. Distillation, 184. fractional, 185. in vacuo, 187. of coal-tar, 1. with steam, 189. Disulphonic acid, anthraquiuone, 117. acids of nitronaphthalene, 12. Double brilliant scarlet, G, 66. reactions of, 318. Dye-bath, preparation of, 284. Dyeing, absorption theory of, 33. acid colouring matters, 289. basic colouring matters, 289. chemical theory of, 32. mechanical theory of, 32. solid solution of, 32. sulphur dyestuffs, 290. Dyestufi's, acid, 35. Acridine, 112. Alizarine, 114. analysis of, 341. application of, 32. azo-, 47. action of sulphuric acid on, 302. azoxy-, 45. basic, 35. books on, ISO. classification of, 33, 342. equalising power, 296. examination of mixtures of, 343. developed, 37. diphenylamine, 124. fastness to acids, 298. alkalies, 298. bleaching, 299. carbonising, 298. light, 297. milling and washing, 297. perspiration, 208. stoving, 298. from amidoazo-compounds, mode of forma- tion, 146. from tetrazo-salts, 69. Flavone and Flavonole, 169. groups of, 39. hydrazone, 76. investigation of, on the fibre, 350. mordant, 36. nitro-, 44. nitroso-, 42. oxy ketone, 114. pyronine, 97. qualitative analysis of, 308. quantitative analysis of, 300. quinoline, 154. 598 INDEX. Dyestuffs, quinoxaline, 151. reactions of, on the fibre, 360. rosaniline, formation of, 87. scries, 82. rosolic acid, 93. stilliene, 45. solubility of, 296. s[)ectroscapic investigation of, 359. structure of, 38. substantive to cotton, 57. synthetic, review of, 174. tetrakisazo-, 74. thiazol, 152. triphenylraethane, 79. colour of, 95. vat, 36. xanthone, 168. Elimination of SO^H, 196. Enolcindoxyl, 160. Eosine A, 103. preparation of, 250. reactions of, 330. BN, 105. reactions of, 331. S, 104. scarlet BB extra, reactions of, 331. spirit, 104. Eosines, the, 102. reactions of, on the fibre, 357. Erika B, 66. Erythrosine, 105. reactions of, 331. G, 105. Ethane from acetylene, 2. Ethylene from acetylene, 2. Ethoxybenzidine, 21, 58. Ethyl'indoxylate, 159. isatogenate, 159. o-nitrophenylpropiolate, 1 59. violet, 92. Eurhodines, the, 132. Euxanthone, 168. F ACID, 14. Fast acid blue R, 102. reactions of, 329. violet A, 2R, 102. B, 102. reactions of, 329. lOB, 93. black, 131, 167. blue, 129. brown G, 67. green 0, 80. preparation of, 225. neutral violet B, 142. Ponceau, 68. red A, 64, 66. preparation of, 230. 13, 66. preparation of, 229. BT, 66. D, 66. reactions of, 317. violet (reddish), 68. Ferrous sulphate, specific gravity of, 389. Fibres, reactions of, 283. Filtration, 190. Fisetine, 170. Flavine, diamond, 66. Flavinduline, 151. Flavone, 171. Flavone and Flavonole dyestuffs, 169. Flavopurpurine, 117, 121. Fluorene in coal-tar, 3. Fluorescein, 99. Iireparation of, 250. Fluorescin, 108. Formaldehyde, 31. analysis of, 268. interaction of, with dimethylaniline, 31. Formation of azo-compounds, 47. diazoaraidocompounds, prevention of, 52. internal azo-compounds, 53. Fractional distillation, 185. Fuchsin. See Magenta. New, 89. reactions of, 325. S. See Acid magenta. Fuming sulphuric acid, analysis of, 266. preparation of, 184. work with, 183. 6 ACID, 16. Gallamine blue, 130. Galleine, 106. reactions of, 333. Gallic acid. 29. [ Oillocyanine DH, 129. preparation of, 257. Gambin B. See Dioiiv. G or Y, 43. K, 42. Garnet, Alizarine, R, 119. Gentianine, 128. Girofle, 143. Glacier blue, 81. Green, acid, 30. reactions of, 326. Alizarine, B, 131. G, 131. S, 120, 122. reactions of, 335. Alsace, J, 43. Anthrai|uinone, GX, 391. Azine, GB, 140. S, 141. Azo, 81. Bindscliedlers, 132. Brilliant, 79. reactions of, 323. Chrome, 91. Columbia, 73. Diamine, B, 73. Diamond, 69. dyestuffs, reactions of, on the fibres, 352 372. Fast, 0, 80. preparation of, 225. Guinea, 81. Helvetia. 80. Iodine, 90. Light SF (yellowish), 80. 599 Green, Malachite, 79. jireparation of, 242. Methyl, 90. Methylene, 128. reactions of, 338. Naphthol, B, 42. Resorcin, 42. reactions of, 313. Solid, 42. Victoria, 80. Green oil, 3. Grey, Benzo, 72. dyestuifs, reactions of, on the fibre, 354. Guinea green, 81. G salt in azo-corabination, 56. H .\ciD, 17. Heating, 182. underpressure, 182. Heavy oil, 3. Heliopurpurines, 391. Helvetia green, 80. Hessian brown BB, 74. MM, 75. purple N, 72. Hexamethylrosaniline chloride, 89. He.xaoxyanthraquinones, 123. History of the Safranines and Aposafranines, 134. Hochst new blue, 93. Hofmann's violet, 90 Homoaurine, 94. Homorosaniline, 84. Hydrazobenzene, 21. Hydrazoues as dyestuffs, 76. Hydrocarbons, percentages of, in coal-tar, 4. polymerisation of, 2. Hydrochloric acid, strength of, 380. Hydrocyanocarbodiphenyliiuide, 164. Hydrometer scales, comparative table of, 390. Hydroxyl compounds, benzene series, 27. naphthalene series, 28. group, acidic nature of, 27. alkylation of, 28. as auxochrome, 38. presence of, in dyestuffs, 28. Hyposulphite vat, 290. Ice colours, 37. Iramedial black, 167. V, 167. blue, 167. sky blue, 167. Indaniines, 131. Indanthrene X, 123. Indazine M, 141. Indian yellow, 168. Indicators, 191. Indigo, 155, 164. analysis of, 305. Baeyer and Drewson synthesis of, 160. from o-nitrobenzaldehyde, 161. K. Heumann synthesis of, 163. of the naphthalene series, 165. preparation of, 263. reactions of, on the fibre, 356, 358. Sandmeyer synthesis of, 164. Indigo, syntheses of, 161. Indigocarmine, 165. Indigo pure, 164. S, 164. salt K, 162. Indigotine, 164. Indigo white, 161 Indirubine, 160. Indogenide, 160. ludoine blue R, 66, 142. Indol, 156. Indophenol, preparation of, 256. white, 126. Indophenols, the, 126. Indophor, 163. Indoxyl, two forms of, 159. Indoxylcarboxylic acid, 163. Indoxylic acid, 160. Induline (spirit soluble), preparation of, 262. reactions of, 340. (water soluble), preparation of, 262. scarlet, 141. Indulines from araidoazobenzene, 143. Ingrain colours, 36. Iodine green, 90. Iris blue, 130. Iron mordants, 293. Isatin, 156. two forms of, 159. a-Isatinanilide, 164. Isatinio acid, 158. Isatogenic acid, 160. Isodiphenyl black, preparation of, 239. Isomerides of Alizarine, 120. Isopurpurine, 117, 122. Isorhamnetine, 170. Janus red, 69. Katigene black, 167. Ketoindoxyl, 160. Ketones, 30. Kyrogene brown, 167. Kyrogene G and R, 167. L ACID, 14. Laboratory, technical, 177. Lactam isatin, 159. Lactim isatin, 159. Lakes, 40. tannin, 35. Lanacyl blue BB, 66. violet B, 63. Lanafuchsine, 66. Lancaster yellow, discovery of, 61. Laurent acid, 14. Lauth's violet, 127. Law, Chrysoidine, 49. Law of Armstrong and Wynne, 1 0. Liebermann and v. Kostanecki, 40. Laws regulating the formation of diazo-com- pounds, 49. rosaniline dyes, 84. Lead peroxide, analysis of, 267. preparation of, 242. Leucaniline, constitution of, 82. Leucaurine, 93. 400 Light green SF (yellowish), 80. oil, 2. Lithol red R, 391. Luteoline, 169, 173. Lyons blue, 90. Madder root, 115. Magdala red, 144. Magenta, 88. preparation of, 243, reactions of, 324. on the fibre, 357. Magenta, Acid, 92. reactions of, 326. hydrochloride, dissociation of, 33. New, 89. reactions of, 325. Malachite green, 79. preparation of, 242. series, 79. sulphonic acids of, 80. Maroon, Alizarine, 119. Martins yellow, 45. reactions of, on the fibre, 357. Mauveine, 143. Mechanical theory of dyeing, 32. Mekong j-ellow G, 74. R, 75. Melanogen blue, 167. Meldola's blue, 129. preparation of, 257. reactions of, 337. Mercuric chloride as oxidising agent, 82. Metachronie brown B, 63. Metallic diazo-compounds, 25. Metanil yellow, 63. Metapheuylene blue B, 144. Methane transformed into benzene and naphthalene, 2. Methyl alcohol, analysis of, 269. alkali blue, reactions of, 328. green, 90. violet 6B, 89. B, preparation of, 245. reactions of, 324. violets, 89. Methylchromone, 172. Methylene blue B, 127. analysis of, 305. preparation of, 258. mode of formation of, 126. reactions of, 337. on the fibre, 357. green, 128. re.aetions of, 338. violet RRA, 3RA, 143. reactions of, 339. Methylrosaniliues, 89. Middle oil, 3. Mikado colours, 46. Milling blue, 141. Mimosa, 153. Mixed dyestulfs, reactions of, on the fibre, 354. Molecular rearrangement of SO^H, 196. weights, 193. Monazo-dyestuft's, 62. Mordant, definition of, 40. Mordant dyes, 36. dyestuH's, structure of, 40. yellow 0, reactions of, 318. Mordants, 292. Morine, 170. Muscarine, 131. Myricetine, 170. Naphtha, 4. Naphthalene, amido-derivatives of, 24. analysis of, 271. from acetylene, 2. from benzene and ethylene, 2. from methane, 2. hydroxyl derivatives of, 28. Indigos from, 165. in heavj- oil, 3. in middle oil, 3. nitration of, 7. purification of, 3. sulphouation of, 10. supply of, 3. used in Indigo synthesis, 3, 163. Naphthalene nucleus, method of imiubering. 7. positions in, 7. series, orientation in, 8. Naphthalene-iSsuIphouio acid, preparation of, 213. Naphthalene sulphonic acids,sulphonation of.l 4 . trisuli'honic acid, pre]>aration of, 219. Naphthazarine, 144. Naphthazine blue, 144. Naphthionic acid, diazo-compound of, 13. description of, 13. preparation of, 217. ortho-, 14. o-Naphthol, 28. ;8-Naphthol, 28. preparation of, 214. Naphthol black B, 68. discovery of, 62. preparation of, 237. 6B, 69. blue. See Meldola blue, black, 67. preparation of, 236. green B, 42. l-Naphthol-3 : 6-disulphonic acid, 15. 2-Naiihthol-3 : 6-disulphonic acid (R acid), 16. prei)aration of, 215. 2-Naphthol-6 : 8-disulphonic acid (G acid), 16. l-Naphtliol-4-sulphouio acid (Neville and Winther's acid), 15. preparation of, 218. 2-Naphthol-6-sulphonic acid (Schaller's acid), 16. preparation of, 214. 2-NaphthoI-8 sulphonic acid (Crocein acid), 16. 2-Naphthol-3 :6 : 8-trisulphouicacid, 16. Naphthol sulphonic acids, 15. analysis of, 280. combination of, with diazo-salts, 50. yellow a, 45. analysis of, 308. preparation of, 226. reactions of, 312. on the fibre, 357. INDEX. 401 Naphthols, analysis of, 280. combination of, with diazo-salts, 50. Naphthyl blue, 141, 143. black N, 69. red, 143. a-Naphth3flaniine, 24. preparation of, 216. diazotisatiou of, 229, jS-Naphthylamine, 24. analysis of, 275. preparation of, 221. 2-NaphtliyIamine-6 : 8-disulphonic acid G, 14. preparation of, 222. l-Naphthylaraine-4 : 7-disul phonic acid, 14. 2-Na]ihthylainine-3 : 6-disulphonic acid, 14. l-Naphthylamine-3-sulphonic acid, 14. l-Naplithylamine-5-sulphonic acid, 14. l-Naphthylamine-6-sulphonic acid, 14. l-Naphthylamiue-7-sulphonic acid, 14. l-Naphthylamine-8-sulphonic acid, 14. 2-Naphthylaraine-6-suIphonic acid, 14. 2-Kaphthylamine-7-sulphonic acid, 14. Naphthylaraine sulphouic acids, 12. analysis of, 281. combination of, with diazo-salts, 50. l-NaphthyIamine-3 :6 :8-trisulphonicacid, 15. preparation of, 219. 2-Naphthylamine-3 : 6 :8-trisulphonicacid, 16. Naphthylamine black D, 69. brown, 66. violet, 150. Naphthylamines, analysis of, 275. combination of, with diazn-salts, 50. Naphthylene red, 71. Navy blue, 92. Neutral blue, 140. dyestuffs, reactions of, on the fibre, 347, 348. red, 133. violet, 133. Fast, B, 142. Neville and Winther's acid, 15, 391. New blueR, 129. coccine, 66. fuchsin, 89. process, 88. reactions of, 325. methylene blue GG, 130. N, 129. Nicholson's blue, 92. Night blue, 91. titration of Naphthol yellow with, 308. Nigrosines and ludulines, the, 143. from nitrophenol, 149. Nile blue A, 130. 2B, 130. o-Nitracetanilide, 23. p-Nitracetanjlide, 23. preparation of, 202. JH-Nitraniline, 23. ?;-Nitraniline, 20, 23. diazo-salt of, 48. diazntisation of, 236. preparation of, 202. red, 63. discovery of, 62. Nitranilines, analysis of, 275, Nitration, benzene series, 5. Nitration, naphthalene series, 7. Nitric acid, strength of, 381. o-Nitroacetocinnamone 162. a-Nitroa!izarine, 119. ;8-Nitroalizarine, 119. o-Nitroanisol, alkaline reduction of, 21. m-Nitrobenzaldehyde, 6, 31. o-Nitrobenzaldehyde, 31. formation of, 162. Nitrobenzene, alkaline reduction of, 21. analysis of, 271. as oxidising agent, 82. preparation of, 119. reduction of, 19. m-Nitrobenzoic acid, 6. Hi-Nitrobeuzonitrile, 6. o-Nitrobenzylideneaniline, 31. Nitrobenzyl chloride, 31. o-Nitrooinnamic acid, 157. Nitro-compounds, as dyestuffs, 44. benzene series, orientation nf, 5. »!-Nitro-compounds, fnrmation of, 6. further nitration of, 6. Nitro-dyestuffs, structure of, 44. reactions of, 346. Nitro-group, acidic influence of, 6. benzene series, 5. naphthalene series, 7. Nitronaphthalene disulphonic acids, 12. sul phonic acids, 12. a-Nitronaphthalene, 24. preparation of, 216. Nitronaphthalenes, reduction of, 24. Nitronaphthylamine sulphonic acids, 13. o-Nitrophenol, 6. p-Nitrophenol, 6. Nitrophenols, Nigrosines from, 149. o-Nitrophenylacetylene, 15S. o-Nitrophenyllactomethylketone, 161, 162. o-Nitrophenylpropiolic acid, 157. Nitrosamine paste, 48. red, 64. Nitroso-compounds as dyestuffs, 42. reactions of, 346. Nitrosodimethylaniline, 23. preparation of, 205. Nitrosodioxynaphthalene. See Dioxin. o-Nitroso-a-naphthol. See Gamhin R. o-Nitroso-(8-naphthol. See Gamhin G or Y. Nitroso - 3 - naplitholsulphonic acid. See Naphthol green B. Nitroso-m-phenylenediamine, 20. Nitrosophenols, 42. o-NitrotoIuene, 6. alkaline reduction of, 21. Nitrotoluenes, analysis of, 271. Oleic acid, detection of, on tlie fibre, 350. Olive, Benzo, 73. Opal blue (Aniline blue), 246. Orange, Acridine, 113. R e.\tra, 113. Alizarine, G, 121. preparation of, 334. Azo, R, 74. Brilliant, R, 66. Cotton, G, 63. 26 402 INDEX. Orange, Cotton, R, 67. dyestulls, reactions of, on the libre, 352, 368. Pyramine 3G, 71. Orange I., 66. II., 66. preparation of, 228. reactions of, 316. III., 63. IV., 63. G, 65. reactions of, 314. GT, 65. Oranges, the discovery of, 61. Orientation of the nitro-compounds (benzene series), 5. in tlie naphthalene series, 8. Ortho-naphthionic acid, 14. Oxazines, 129. Oxidation of anthracene, 3. Oxindol, 156. Oxyazobenzeue with sulphuric acid, 53. O.xyazo-compounds, 63. discovery of, 61. formation of, 47. laws regulating formation of, 49. OT-Oxybenzaldehyde, 31. ^<-Oxy-o-p-dinitrodiphenylamine, 167. Oxyketone dyestutfs, 114. reactions of, 349. Oxy naphthoquinone, 115. Paeonine, 94. Palatine red, 66 scarlet, 65. Paraaurine, 94. Pararosaniline, 84. Pararosolic acid, 94. Patent blue A, 81. V, 80. reactions of, 327. Pentaoxyanthraquinones, 123. Plienanthrene in coal-tar, 3. Phenol, analysis of, 278. conversion of, into salicylic acid, 29. formation of, 27. in middle oil, 3. nitratiiin of, 6, 27. purification of, 4. sulphonic acids of, 27. Phenols, in heavy oil, 3. percentages in coal-tar, 4. Phenolphthalein, 98. o-l'lienol]ihthaleiu, 99. anhydride, 99. Phenol-o-sulphonic acid, 27. Phenol-;).sulplionic acid, 27. Phenylacridine, 112. Phenyl ammonium chloride, 26. derivatives of rosaniline, 90. Phenylene blue, 131. brown. See Bismarck brotrn. TO-Phcnylenediamiue, 20, 60. analysis of, 277. p-Plienyloncdiamiue, 20. diazotisation of, 20. ;)-Phenylenediamine-azo-xylidine, 59. Phenylglycine, 163. Phenylglycine-ocarboxylic acid, 163. Phenylrosinduline, 146. Phloxine, 105. analysis of, 332. P, 105. Phosgene, 31. process, 88. used in the preparation of aromatic ketones, 30. Phosphine, 112. Phthaleius, the, 98. Phthalic acid from naphthalene, 30. anhydride, 30. analysis of, 279. Phthalophenone, 100. Picric acid, 28, 45. formation of diazooxy-compound from, 52. reactions of, 312. on the fibre, 357. Pitch, 3. Polyazo-componnds, colours with sulphuric acid, 54. Polymerisation of hydrocarbons, 2. Ponceau 2G, 65. 4GB, 64. reactions of, 314. 2R, 66. 3R, 66. 5R, 68. 6R, 66. 4RB, 68. Crystal, 64. Fast, 2B, 68. Ponceaux, 64. discovery of, 61. Preparation of diazo-salts, 24. Primary disazo-dyestuft's, 66. Primuline yellow, 153. discovery of, 62. preparation of, 263. reactions of, on the fibre, 357. Propylene from methane, 2. Prune pure, 130. Pseudo-base of rosaniline, 86. Pseudnindoxyl, 160. Pseudoisatin, 159. Puiri, 168. Purification of anthracene. 3. coal-tar, 2. naphthalene, 3. Purple, Hessian, N, 72. I'urpurine, 121. Pyramine orange 3G, 71. I'yrene in coal-tar, 3. Pyrogene blacks and blues, 167. Pyrouine, 98. Pyronine dyestulfs, 97. G, 97. Pyrrol black, 167. QUEROK.TINE, 170. Quinizarine, 118, 120. Quinoline bases in heavy oil, 3. blue, or Oyanine, 154. dyestulls, 154. red, 154. INDEX. 403 Quinoline yellow, 154. S, 154. Quinone structure of rosaniline salts, 8<^. Quinoiieoximes (see Nilroso-compouiuh), 42. Quinoxaline dyestuHs, 151. R A( ID, 16. preparation of, 215. 2R acid, 17. Reactions of dyestuffs on the fibre, 360. Reagents, 192. Rearrangement, molecular, of SO^jH, 196. Red, Acridine, 98. Alizarine, S, 120. Atlas, 63. Cloth, B, 68. 3B, 68. G, 68. 0, reactions of, 319. Congo, 57, 70. analysis of, 301. reactions of, 321. on the fibre, 357. Corallin, 94. dyestuffs, reactions of, on the fibre, 351, 373. Fast, 64, 66. A, 66. preparation of, 230. B, 66. preparation of, 229. BT, 66. D, 66. reactions of, 317. diamine, preparation of, 232. Janus, 69. Lithol, R, 391. Magdala, 144. Naphthyl, 143. Naphthylene, 71. Neutral, 133. p-Nitrauiline, 63. Nitrnsamine, 64. Palatine, 66. Priniuline, reactions of, on the fibre, 357. Quinoline, 154. Sorbine, 66. Tuluylene, 133. violet 4RS, 92. 5RS, 92. Wool, G, 391. Red-brown dyestuffs, reactions of, on the fibre, 351. Reseda luteola, 173. Resorcin brown, 67. discovery of, 62. green, reactions of, 313. See Solid green. Resorcinol, analysis of, 279. Review of synthetic dyestuffs, 174. Rhamnazine, 170. Rhamnetine, 170.' Rhodamine B, 100. preparation of, 252. 3B, 101. Rhodamine G, 102. S, 101. Rhodamines, the, 101. Rhndamines on cotton, 35. Roccelline, preparation of, 230. Root, Madder, 115. Rosamine, Acid, A, 102. Rosaniline, ammonium base of, 86. base, constitution of, 83. formation of salt from, 85. blues, 90. carbinol base of, 85. chlorides of, 85. constitution of, 82. dyes, constitution of, 85. laws regulating formation of, 84. methods of formation, 87. phenyl and tolyl derivatives of, 90. phenylation of, 90. quinone structure of salts, 86. series, 82. sulphonic acids of, 91. ^o-Rosaniline, 84. Rosanilines, necessary positions of amido- groups, 85. Rosazurine B, 71. Rose Bengal, 105. 3B, 106. reactions of, 332. Rosinduliue G, 140. 2G, 140. Rosolic acid dyestuffs, 93. Rosophenine S6, 66. Rota's analysis of dyestuffs, 341. B salt in azo-combination, 56. Ruberythric acid, 1 1 5. Rubia tinctorum L. 115. Rufigallol, 123. S ACID, 14, 16. 2S acid, 17. Safranine MN, 143. T, 142. preparation of, 260. reactions of, 339. Safranines, the, 141. constitution and history of, 134. mode of formation of, 141. Safranole, 138. Salicylic acid, 29. analysis of, 279. Salt colours. See Dir''ct dyes. solution , specific gravity of, 386. Salting out, 191. Scarlet, Azine, G, reactions of, 340. Biebrich, 68. reactions of, 319. Cloth, G, 68. Cochineal, 65. Crocein, 8B, 68. extra, 68. Crystal, 6R (Crystal Ponceau), 64. analysis of^, 303. Double brilliant, G, 66. reactions of, 318. Eosine, BB extra, reactions of, 331. Induline, 141. Palatine, 65. Wool, R, 65. 404 INDEX. Schliffer's acid, Ifi. Schoellkojif acid. 14. Secondav}' disazn-dyestuirs, 67. Separation of dyestull's by amyl alcohol, 357 Silk dyeiiif,', 286. Sky blue. Diamine, 71. Immedial, 167. Sodium acebite, specific gravity of, 387. bisulphite, specilic gravity of, 386. carbonate, strength of, 385. nitrite, analysis of, 268. sulphate, specific gravity of, 386. sulphide, analysis of, 268. Solid green (Fast green 0), 42. preparation of, 225. solution theory of dyeing, 32. Soluble blue (Water blue), i'2. preparation of, 249. reactions of, 3"28. Sorbine red, 66. Spectroscopic investigation of dyestulls, 359 Spirit cyanosine, 105. cosine, 104. yellow K, 63. St Denis red, 72, Stilbene dyestuffs, 45. yellow, 46. Structure of dyestuffs, 38. of mordant dyestuffs, 40. Styrene from acetylene, 2. from benzene and ethylene, 2, Substantive dyes, 35. cotton dyes, 67. Sudan I., 65. II., 65. Ill,, 68. G, 65. brown, 66. Sulphanil black, 167. p-Sulphanilic acid, 23. analysis of, 276. diazotisation of, 228. preparation of, 204. Sulphate of alumina, specific gravity of, 387 Sulphide colours. See Unlphur colours. Sulphonation, benzene series, 9. naphthalene series, 10. Sulphonaznrine, 72. Sulphonic acid group, acid character of, y. methods of inlrodvicing, 9. reactions of, 10. acids (benzene series), orientation of, 10. purification of, 10. of nitronaphthalene, 12. of the Malachite green series, 80. (naphthalene series), 10. ofnaphthols, 15. of naphthylaniincs, 12. of Rosanilinc dyes, 91. Sulphur black T, 167. preparation of, 265. colours, 166. dyeing of, 290. Sulphuric acid, action of azo-dyestufl's on, 302. fuming, analysis of, 266. work with," 183. strength of, 383. Sun yellow, 46. Synthetic dyestuffs, review of, 174. Syntheses of Indigo, 161. Tannic acid, detection of, on the fibre, 350. strength of, 385. Tannin dyestull's. See Basic dyestuffs. lakes, 35. Tartar emetic, specilic gravity of, 388. Tartrazine, 76. Technical laboratory, 177. Terracotta K, 67. Tetraamidoilitiilylphenylniethane, 113. preparation of, 253. Tetrabromoliuorescein, 103. Tetrakisazo-dyestull's, 74. Tetrami-tliybhaiiiidnbenzhydrol, 30. TetranietbyMianiidulirnzophenone, 17, 30. TetramethyMianiidodioxydiphenylmethane, 97. Tetraniethyldiamidodiphenylnu'thane, 77. oxidation of, 30. oxide, 98. Tetraoxyanthraquiuone, 122. Tetrazobenzidiue chloride, 69. salts of, 57. Tetrazodiphenyl. See Tetrazol)eif:ulinr. Tetrazo salts, azo-dyestulfs from, 69. Thiazines, 126. Thiazol dyestuffs, 152. Thiocarbanilide, preparation of, 209. Thiocarmiue R, 128. Thioflavine S, 153. T, 153. Thiogene blue, 167. Thionine blue 0, 128. Thionol black, 167. Titanous chloride, analysis with, 302. as a reagent, 358. Tolidine, 21. analysis of, 278. diazotisation of, 231. disulphonic acid, 59. Toluene, analysis of, 270. from coke ovens, 3. in light oil, 3. oxidation of, 29. purification of, 3. yearly output, 3. Toluidine, determination of, 273, 276. Toluidine blue 0, 126. reactions of, 338. o-Toluidine, 19. Toluylene blue, 132. brown, 75. red, 133. »H-Toluylenedianiine, 20. preparation of, 207. p-Toluylenediamine, 20. Tolyl derivatives of rosanilinc, 90. Triethylrosaniline iodide, 90. Trinitrotriphenylmethaue, 82. Trioxyanthraquinones, 121. Triphenylmethane, 82. dyestuffs, colour of, 95. division of, 79. Malachite green series, 79. INDEX. 405 Triphenylmethane dyestuffs, Rosaniline series, 8-2. Rosolic acid series, 93. Tropiidlines, discovery of, 61. Turkey-red, nature of, 36. oil, 292. analysis of, 281. Union fast claret, 68. Urauine, 99 reactioDS of, 330. Vat colours, dyeing of, 290. dyes, 36. Victoria blue B, 91. R, 91. 4R, 91. green, 70. violet 4BS, 6.1. Vidal black, 167. Violamine B, 102. G, 102. R, 102. 2R, 102. Violet, Acid, eBN, 95. Acid, N, reactions of, 327. Alkali, 93. Amethyst, 143. Benzo, R, 71. Chrome ( Bayer), 91. (Geigy), 95. Crystal, 89. reactions of, 325. Diamine, N, formula of, 236. dyestutt's, reactions of, on the fibre, 35;- 362. Ethyl, 92. Fast (reddish), 68. acid. A, 2R, 102. B, 102. reactions of, 329. lOB, 93. Hofmann's, 90. Lanacyl, B, 63. Lauth's, 127. Methyl, 6 B, 89. , B, preparation of, 245. 1 reactions of, 324. Methylene, RRA, 3RA, 143. reactions of, 339. [ Naphthylamine, 150. Neutral, 133. j Red, 4RS, 92. 5RS, 92. Victoria, 4BS, 65. Wool, S, 63. j Violets, Acid, 92. I Methyl, 89. 1 Water blue, 92. White, Indigo, 161. Indophenol, 126. Wool black 6B, 67. dyeing, 285. redG, 391. scarlet R, 65. violet S, 63. Xanthone, 169. dyestutfs, 168. Xylene, analysis of, 270. Xylenes, from coal-tar, 3. Xylidine, analysis of, 276. Yellow, Acid, 63. Acridine, 113. Alizarine, 64. A, 114. preparation of, 254, C, 114. FB, 73. GG, 65. R, 65. Carbazol, 71. Chloramine, 153. Chrome, D, 66. Corallin, 94. Cotton, G, 70. R, 66. Crumpsall, 66. Diamond, 65. G, 66. R, 66. Direct, 46. dyestuffs, reactions of, on the fibre, 352, 368. Indian, 168. Martius, 45. reactions of, on the fibre, 357. Mekong G, 74. R, 75. Metanil, 63. Mordant, 0, reactions of, 31S. Naphthol, S, 45. analysis of, 308. preparation of, 226. reactions of, 312. on the fibre, 357. Primuline, 153. Quinoline, 154. S, 154. Spirit R, 63. Stilbene, 46. Sun, 46. Zinc ammonium chloride, preparation of, 221. dust, analysis of, 267. PRINTED BY NEILL AND CO., LTD.. EDISBUEOH. V ."-^i-j-^vc- ..■„V,l,v ■ .-; ■ tiii} '4 'M