EXCHANGE 231920 THE SYNTHESIS OF MONO-AMINO FLAVONES, OF FLAVONE-AZO-BETA- NAPTHTHOL DYES AND OF OTHER FLAVONE DERIVATIVES DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY, IN THE FACULTY OF PURE SCIENCE OF COLUMBIA UNIVERSITY. VI^^YX ot r>" TV H R8i T V$ " BY JOSEPH K. MARCUS, B. A. New York City 1918 CHAUNCEY HOLT COMPANY 227-239 West 17th Street New York THE SYNTHESIS OF MONO-AMINO- FLAVONES, OF FLAVONE-AZO-BETA- NAPTHTHOL DYES AND OF OTHER FLAVONE DERIVATIVES DISSERTATION SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF DOCTOR OF PHILOSOPHY, IN THE FACULTY OF PURE SCIENCE OF COLUMBIA UNIVERSITY. BY JOSEPH K. MARCUS, B. A. New York City 1918 CHAUNCEY HOLT COMPANY 227-239 West 17th Street New York TO MY PARENTS 451718 ACKNOWLEDGMENT The author is indebted to Professor Marston Taylor Bogert for his kind encour- agement and guidance in carrying out this work. c' Hrf OiN ZZT OH 'COCHj I CH V -COOH M Br-CH-C t M, OH un.ro CH-COOH CH< C.H, HCI ai CHBr t HO-/ \ N CH 1 > / * S\ CH- CO- ABSTRACT OF THE DISSERTATION 1. What was the object of the investigation? 2. To what extent was the object attained? 3. What contribution, actually new to the science of chem- istry, has been made? 1. The intense yellow color of some of the naturally occurring hydroxy derivatives of flavone * (certain of which are valuable as dyes; i. e., Quercetin-l^S'^'jalpha-penta- hydroxy-flavone in Quercitron Bark, and Morin 1,3,2',4', alpha-penta-hydroxy-flavone in Old Fustic) made it seem of interest to extend the investigation of the flavone series to the preparation and study of the amino derivatives in order (1) to record the auxochromic effect of the amino group on the flavone nucleus ; and (II) to couple the diazotized amines with betanaphthol, thus incorporating the flavone, azo and naphthalene chromophores in one compound, with the hope of obtaining red or blue dyes. Further, (III) a method was sought for making flavone or flavone derivatives which should be dependent on the use of easily available materials and of few reactions. 2. (I) 2 / -Amino-flavone, 3'-amino-flavone, and 4'-ami- no-flavone were synthesized by the reduction of a mixture of nitro-flavones resulting from the nitration of flavone. The positions of the amino groups in these amines were determined by converting them to the corresponding phenols. Two of the phenols obtained were identical with 3'-hydroxy-flavone 5 and 4'-hydroxy-flavone * (both previously prepared by St. v. Kostanecki). The third phenol was found to be 2'-hydroxy- flavone, and constitutes the sixth of the eight possible mono- hydroxy-flavones to be synthesized. 8 These three amines are all yellow, in contrast to the cor- responding hydroxy-flavones which are white. 4'-Amino- flavone possesses the noteworthy property of imparting fluores- cence only to neutral solvents, which contain the hydroxyl group. (II). 4'-Amino-flavone was diazotized and coupled with beta-naphthol, giving flavone (4')-azo-beta-naphthol ** which dyed silk and wool a fast bright red color. Flavone ('')-azo- beta-naphthol ** and flavone (3')-azo-beta-naphthol ** were synthesized in similar manner from 2'-amino-flavone and 3'- amino-flavone and gave fast orange shades on silk and wool. * See structure I. ** See structures II, III and IV. (III). 2-Nittb-fiaVaftcme l -was ' synthesized directly from para-nitro-phenol and beta-brom-hydrocinnamic acid, but in poor yield. Other compounds which have been synthesized for the first time are: 2'-acetoxy-flavone, 2 / -diacetyl-amino-flavone, 3'-diacetyl-amino-flavone, 4'-diacetyl-amino-flavone, beta-phe- noxy-hydrocinnamic acid, the barium salt of a disulfo-deriva- tive of beta-phenoxy-hydrocinnamic acid, beta-ortho (or para)-hydroxy-phenyl-cinnamic acid, and methyl-brom-cinna- mate. 3. The chief contribution of this paper to the science of chemistry may be briefly stated, then, as the synthesis of cer- tain mono-amino-flavones, all of which possess a yellow color, and of certain flavone-azo-beta-naphthol dyes which have deeper colors than the most highly hydroxylated flavones oc- curring in nature. Incidently, 4'-amino-flavone has been found (as far as the solvents which were tried are concerned) to possess the unusual property of causing fluorescence only in neutral solvents which contain the hydroxyl group. THE SYNTHESIS OF AMINO FLAVONES, OF FLAVONE-AZO-BETA-NAPHTHOL DYES, AND OF OTHER FLA- VONE DERIVATIVES INTRODUCTORY Many of the yellow coloring matters occurring in thfe plant kingdom have been shown to be hydroxy derivatives of flavone (benz-2-phenyl-gamma-pyrone).* Aside from the general in- terest attaching to these compounds because of their ubiquitous occurrence in nature, they are of particular importance by reason of the successful commercial application of some of them as fast dyes; i. e., Quercetin (l,3,3',4',alpha-penta- hydroxy-flavone) the yellow dyestuff in Quercitron Bark, and Morin (1,3,2',4', alpha-penta-hydroxy-flavone) which, together with Maclurin (a penta-hydroxy-benzo-phenone), constitutes the coloring matter of Old Fustic. In view of the strong chromophoric character of the benz- 2-phenyl-gamma-pyrone nucleus displayed in these compounds, it was considered of interest to extend the investigation of the flavone series to the preparation and study of the amino derivatives, in order to record the auxochromic effect of the ami- no group on the flavone nucleus, and to couple the diazotized amines with beta-naphthol, thus incorporating the flavone, azo and naphthalene chromophores in one compound, with the ex- pectation of obtaining red or blue dyes this expectation being warranted by the numerous examples of compounds in which a deepening in color is brought about by the piling up of chro- mophores. Further, the methods which have been elaborated for the preparation of flavone involve either the use of mate- rials which are difficult to obtain in quantity or the employment of a long succession of reactions in which the yields at some points are disappointing. 6 Thus it seemed desirable to devise a new method for making compounds of this series which would not possess the disadvantages above named. With these objects in view, the investigation reported in this paper was undertaken. The work was successful in regard to (I) the preparation of amino flavones, and (II) the production of azo-flavone dyes; but was not fruitful of (III) the sought for better method for making flavone or its derivatives : (I). Three mono-amino-flavones, 2'-amino-flavone, 3'- amino-flavone and 4'-amino-flavone, were obtained by the re- * See structure I. duction of a mixture of mono-nitro-derivatives resulting from the nitration of flavone. The isomeric nitro compounds were not isolated because they possessed too little difference of solubility in the solvents tried to give a satisfactory separation. The isolation of the individual amino-flavones, however, was effected by taking advantage of their differing basicity and solubilities. The position of the amino group in each one of the three amino-flavones which were synthesized was determined by conversion of the amine, thru its diazonium compound, into the corresponding phenol. Two of the phenols, thus obtained, were found to be identical with 3'-hydroxy-flavone 5 and 4'-hydroxy-flavone, 4 which were both previously prepared by St. v. Kostanecki by another method. The third phenol proved to be 2'-hydroxy- flavone which has been hitherto unknown. The position of the hydroxyl group in 2'-hydroxy-flavone was determined by decomposing it with sodium ethoxide * 7 into salicylic acid and ortho-hydroxy-anisole. The noteworthy characteristics of the amines are : 1. They are all yellow; the 2'-amine being pale yellow; the 3'-amine, lemon yellow ; and the 4'-amine, golden yellow thus the amino group seems to exert a stronger auxochromic influence than the hydroxyl group on the flavone nucleus, since 2'-hydroxy-flavone, 3'-hydroxy-flavone, and 4'-hydroxy-flavone are all white. 3'-Amino-flavone and 4 / -amino-flavone were found to dye wool and silk directly a light yellow color. 2. The 4'-amino-flavone stands out in sharp contrast to the other two amines, especially in those properties relating to color effect; i. e., its color is a deeper yellow than that of the other amines ; it produces an intense fluorescence in certain solvents (the unusual nature of the fluorescent property of this amine is that it seems to be manifested only in solvents, which contain the hydroxyl group), whereas the 2' and 3' isomers show no fluorescence in any solvent; its reduction with magnesium in alcoholic hydrochloric acid solution pro- duces an intensely purple colored solution, in contrast to the light orange color developed in each case by similar treatment of the other two amines ; ** a bright red dye is obtained by coupling the diazotized 4'-amino-flavone with beta-naphthol, whereas the 2' and 3' amines, when treated in the same way give two orange dyes. Noteworthy, also, are the nitration products of flavone altho the individual nitro derivatives were not isolated, an ultimate analysis of the nitration mixture indicated that it was composed of mono-nitro-flavones ; and this was corroborated * See equation III. ** Anthocyan formation possibly takes place in this reaction. 10 by the subsequent isolation of three mono-amines (above) which were derived from the nitro-flavone mixture. The fol- lowing compounds, then, must have resulted from the nitration of flavone 2'-nitro-flavone, 3 / -nitro-flavone and ^-nitro-fla- vone. Thus, all the possible mono-nitro products arising from substitution in the phenyl nucleus of flavone have been formed, and none in which the benz ring has been attacked. This may be a case of steric hindrance; and it would be of interest to learn whether further nitration of mono-nitro-flavone would be limited to the phenyl nucleus. (II). A bright red dye of structure (IV),* fast to light and alkalis, was obtained by coupling the diazotized 4'-amino- flavone with beta-naphthol ; and two orange dyes of structures (II) * and (III),* of like fastness, resulted by the similar coupling of each of the diazotized 2' and 3' amino-flavones respectively. (III). St. v. Kostanecki showed that flavone may be conveniently prepared by successive treatments of flava- none * ** with bromine and potassium hydroxide. But, since the formation of flavanone, as carried out by the same investi- gator, involves the use of ortho-hydroxy-anisole which is diffi- cult to obtain in quantity, the following attempt was made to synthesize it from cinnamic acid which is readily available: Beta-phenoxy-hydrocinnamic acid was prepared by the action of phenol on beta-brom-hydrocinnamic acid, which in turn was obtained from cinnamic acid and hydrogen bromide. The hope that the action of anhydrous aluminum chloride on beta-phenoxy-hydrocinnamyl chloride would effect an internal condensation to form flavanone, similar to the condensation of beta-phenoxy-cinnamyl chloride to form flavone, 2 was not realized. An attempt was also made to accomplish the internal condensation of free beta-phenoxy-hydrocinnamic acid t by the employment of concentrated sulphuric acid as a dehydrating agent, but the result was the formation of a disulfo-beta- phenoxy-hydrocinnamic acid instead. Further failure to effect condensation of the free acid resulted from the use of other dehydrating agents such as phosphorus pentoxide, anhydrous zinc chloride or fuming stannic chloride. Because of the well known influence of the nitro group in a benzene ring on the lability of the hydrogen atom lying in the meta position to it, it was considered probable that flavanone ring formation would be successful with beta-para- nitro-phenoxy-hydrocinnamic acid. With the purpose of ob- taining the latter substance, para-nitro-phenol was heated with beta-brom-hydrocinnamic acid, but instead of the expected acid, a compound which possesses the empirical formula for, * See structures. ** See structure V. t See equation I. 11 and is believed to be, 2-nitro-flavanone was obtained. The course of the reaction was doubtless a preliminary metathesis between para-nitro-phenol and beta-brom-hydrocinnamic to form hydrogen bromide and the expected acid which immedi- ately condensed to form 2-nitro-flavanone with the elimination of water.* However, in view of the small yield (2 per cent of the calculated amount) of the nitro flavanone obtained, the third part of the investigation must be considered successful only in so far that one flavanone derivative has been prepared in poor yield by a new rapid method. Not enough of the compound was obtained to convert to the nitro-flavone. The procedure adopted in this paper for the preparation of flavone is a modification of the one devised by Ruhemann. 2 It was found that the interaction of ethyl-phenyl-propiolate with sodium phenolate gave not one, as stated by Ruhemann, but two esters which on saponification yielded two isomeric acids, one of which corresponds with the beta-phenoxy-cin- namic acid described by the above worker and the other of which has been shown to be either beta-ortho-hydrpxy-phenyl- cinnamic acid or beta-para-hydroxy-phenyl-cinnamic acid. The phenyl propiolic acid used in the flavone synthesis was prepared by a modification of the method described by Sudborough and Thompson. 3 The other compounds which were prepared for the pur- pose of characterization of the amino flavones or hydroxy flavones are : 2'-diacetyl amino-flavone, 3'-diacetyl amino- flavone, 4'-diacetyl amino-flavone, 2'-acetoxy-flavone, 3'- acetoxy-flavone and 4'-acetoxy-flavone. EXPERIMENTAL I and II. Beta-Phenoxy-C i n n a m i c Acid, C 6 H 5 C(OC 6 H 5 ) :CH. COOH Ruhemann states that ethyl-beta-phenoxy-cinnamate may be prepared by adding ethyl phenyl propiolate to a "warm" mixture of sodium phenolate and phenol. 12 In an attempt to duplicate his synthesis, the connotation of "warm" was taken to be about 60-70 ; but in carrying out the re- action at this temperature, only part of the sodium phenolate dissolved and a very impure product which distilled over a wide range (between 140 and 215 at 12 mm.), and smelled of ethyl-phenyl-propiolate was obtained. It was found, however, that when ethyl-phenyl-propiolate was added to sodium phenolate above 125, the phenolate dis- solved completely and the reaction was accompanied by an evolution of heat. *See equation II. 12 Further, it was found desirable to use a xylene solution of phenol in preparing sodium phenolate the use of phenol alone necessitates a very slow addition of the sodium since too rapid an addition causes the temperature to rise to the boiling point of phenol with consequent charring of some of the sodium phenolate. The presence of xylene confines the rise in temperature of the mixture to its boiling point and therefore the sodium may be added more rapidly. The reaction between ethyl-phenyl-propiolate * and sodi- um phenolate suspended in xylene and an excess of phenol was carried out at 140-150. The reaction product was treated according to the directions of Ruhemann. After the excess of phenol, xylene and ether had been removed, the product gave on distillation at 18 mm. : 10 g. of a rather viscous colorless liquid from 203 to 216; 116.1 g. of a very viscous colorless oil from 216 to 219 (Ruhemann gives the B.P. of ethyl-beta-phenoxy-cinnamate as 204 to 205 at 10 mm.). The latter fraction solidified (over night) to a white crystalline mass. M.P. 37-45 (Ruhemann gives the M.P. of ethyl-beta-phenoxy-cinnamate as 73-74). The 116.1 g. fraction was saponified with alcoholic sodium hydroxide, but, contrary to the finding of Ruhemann, gave not only beta-phenoxy-cinnamic acid but also another acid. They were separated as follows : The mixture of acids was dissolved in 250 cc. of boiling alcohol. On cooling, broad prisms came down at first, and later fine needles began to appear. At this point the warm liquid was poured off from the precipitate of prisms. The decanted solution deposited chiefly the needle crys- tals, and when cool was filtered. The precipitate was re- crystallized five times from hot ethyl alcohol and the result was 49 g. of a fluffy precipitate of fine white needles, which softened at 126 and melted at 139-140 with evolution of gas. This product was fairly pure beta-phenoxy-cinnamic acid and was used in the preparation of flavone (q.v.). For pur- poses of comparison with the acid described by Ruhemann, * The ethyl-phenyl-propiolate used in this reaction was prepared as described by Perkin 10 . It was purified by distillation in vacuo. The phenyl propiolic acid was prepared by a modification of the method of Sudborough and Thompson 3 , by using ethyl di-brom-cinnamate instead of di-brom-cinnamic acid, because, as these investigators have shown, a much greater proportion of alpha-brom-cinnamic acid is formed directly from the ester than from the free acid in the first treatment with alcoholic alkali 11 . Also the alpha-brom-cinnamic acid, alpha-allo-brom- cinnamic acid and phenyl propiolic acid were all recrystallized from benzene instead of from chloroform and petroleum ether. The ethyl di-brom- cinnamate was prepared by the method of Perkin. Perkin's method for preparing phenyl propiolic acid involves fewer reactions than the method of Sudborough and Thompson, but was found to give a poor yield (33% of the amount calculated from the ethyl dibrom- cinnamate). 13 some of the above product was further recrystallized (three times) from hot alcohol with the production of a pure sub- stance that softened at 127 and melted at 143-145 (corr.) with decomposition. Ruhemann gives the softening point as 125 and melting point as 143. Subs. 0.3213: CO 2 , 0.8823; H 2 O, 0.1503. Calc. for CisHiaOs: C, 75%: H, 5.0%. Found : C, 74.9% ; H, 5.2%. The compound agrees in other properties with the acid described by Ruhemann. The precipitate of broad prisms (8 grams) was recrystal- lized six times from hot ethyl alcohol and 1.7 g. of a pure substance softening at 169 and melting at 176-177 (corr.) was obtained. This substance is not mentioned by Ruhe- mann. Subs. 0.2110: CO 2 , 0.5806; H 2 O, 0.0968. Calc. for Ci5Hi 2 O 3 : C, 75.0%; H, 5.0%. Found: C, 75.1%; H, 5.1%. The analysis shows it to be an isomer of beta-phenoxy- cinnamic acid. From its properties (q.v.) it is believed to be either beta-ortho-hydroxy-phenyl-cinnamic acid or beta- para-hydroxy-phenyl-cinnamic acid. The formation of either of these compounds in the above reaction would be analogous to the formation of beta-para-hydroxy-phenyl-hydrocinnamic acid from phenol and allo-cinnamic acid. 13 This compound gives positive tests for the phenolic hy- droxyl group with Liebermann's reagent and with a solution of titanium dioxide in concentrated sulphuric acid. It does not give a coloration in water or alcohol solution with ferric chloride. A solution of the substance in aqueous sodium carbonate reduces potassium permanganate but no benzaldehyde odor results, thus indicating the absence of the C 6 H 5 CH : group, which shows that the substance is not alpha-hydroxyl-phenyl- cinnamic acid. It is not alpha-phenoxy-cinnamic acid, since this substance melts with no evolution of gas. The two remaining possibilities are beta-ortho-hydroxy- phenyl-cinnamic acid or beta-para-hydroxy-phenyl-cinnamic acid. In analogous manner to the behavior of coumarinic acid, beta-ortho-hydroxy-phenyl cinnamic acid should yield, on fusion, a coumarin derivative. The compound in ques- tion, however, decomposes at its melting point with evolution of carbon dioxide. Therefore this method of fixing the posi- tion of the hydroxyl group could not be used. Lack of a sufficient supply of the substance prevented further investi- gation to decide between the ortho and para structures. The compound dissolves in concentrated sulphuric acid, forming a bright yellow solution. It decolorizes a chloroform solution of bromine. Is soluble in hot ethyl alcohol, toluene or ligroin (100-110) ; insoluble in hot water or carbon disul- phide. 14 Flavone (Benz-2-phenyl-gamma-pyrone) was prepared, with few modifications, by the method of Ruhemann, 2 in which the acid chloride of beta-phenoxy-cinnamic acid is treated with anhydrous aluminum chloride. It was found that the quanti- ties of benzene and aluminum chloride, indicated by Ruhe- mann, could be cut down without affecting the yield of flavone : 320 g. of benzene and 60 g. of anhydrous aluminum chloride were used for 30.5 g. of beta-phenoxy-cinnamic acid. The crude flavone was recrystallized from ligroin (100-110). The yield of flavone was 85% on the calculated amount. Nitration of Flavone was effected by the action of nitric and sulphuric acids on a solution of flavone in glacial acetic acid. It was found necessary to dilute the sulphuric acid with glacial acetic acid, since the use of the former acid alone gave rise to the formation of higher than mono-nitro derivatives. A mixture of three white mono-nitro-flavones was obtained. All attempts to limit the action of nitric acid on flavone to the formation of only one nitro flavone derivative failed. 60.5 g. of flavone were dissolved in 60 cc. of glacial acetic acid, and 180 cc. sulphuric acid (1.84) were slowly added thereto. 32 cc. (3 cc. more than the theoretical amount re- quired for the formation of a mono-nitro-flavone) of a glacial acetic acid solution of nitric acid (1.5) containing 0.58 g. of nitric acid per cc. of solution were slowly added, while cooling, to the above flavone mixture. After standing at the ice-box temperature for three days, the solution was poured into ice and water. The faint yellow colored precipitate that came down was filtered, well washed with water, and dried over sulphuric acid in vacuo. The 69 g. of nitro flavone thus obtained were dissolved in 350 cc. of boiling glacial acetic acid and on cooling, the pale yellow solution deposited 39 g. of a white crystalline product, which when dry, melted from 174 to 205. Some of this product was prepared for analysis by an- other crystallization from glacial acetic acid. M.P. 175-206. Subs. 0.3112: CChz, 0.7677; H 2 O, 0.0871. Calc. for Ci*HaO 4 N: C, 67.4% ; H, 3.3%. Found : C, 67.3% ; H, 3.2%. Subs. 0.2813: 13.6 cc. nitrogen at 23, 752 mm. Calc. for CwHgOfcN: N, 5.2%. Found : N, 5.4%. The analysis together with the wide range of melting point indicates that the material was composed of a mixture of mono-nitro-flavones, and its subsequent conversion (q.v.) into 3'-amino-flavone and 4'-amino-flavone proved that it con- sisted of 3'-nitro-flavone and 4'-nitro-flavone. This mono-nitro-flavone mixture is slightly soluble in hot ether, ligroin (100-110) or carbon tetrachloride ; insoluble in hot carbon disulfide or petroleum ether ; moderately soluble in hot glacial acetic acid, acetic anhydride, acetone, ethyl alcohol, methyl alcohol, benzene, chloroform, nitro-benzene, toluene, 15 xylene, ethyl acetate, amyl alcohol (technical) or amyl acetate ; very soluble in cold aniline and fairly so in cold pyridine. It is soluble in cold concentrated sulphuric acid or con- centrated hydrochloric acid. It is insoluble in cold or boiling aqueous sodium hydroxide, concentrated or dilute. To the hot glacial acetic acid filtrate from the above 3' and 4' nitro flavones were added 200 cc. of hot water, and on standing over night, 19 g. of a white crystalline product came down which, when dry, melted at 143 to 168. Some of this product was prepared for analysis by another crystallization from glacial acetic acid. M.P. 148-170. Subs. 0.3121: C0 2 , 0.7709; H 2 O, 0.0976. Calc. for CisHgO^N: C, 67.4% ; H, 3.3%. Found : C, 67.4% ; H, 3.5%. Subs. 0.2464: Nitrogen 11.7 cc. at 25, 759 mm. Calc. for Ci 5 H 9 O4N: N, 5.2%. Found: N, 5.3%. The conversion of this product into 2'-amino-flavone and 3'-amino-flavone (q.v.), together with its analysis, proved that it was composed of a mixture of 2'-nitro-flavone and 3'-nitro- flavone. No 4'-nitro-flavone was present in this product as was indirectly proved by the absence of fluorescence in an amyl alcohol or other solution of the amine mixture derived there- from the presence of 4'-amino-flavone would have caused an intense blue or green fluorescence. Solubilities, similar to those of the mixture of 3' and 4' nitro-flavones, are possessed by this product. 2 / -Amino-flavone was obtained by reduction, with stan- nous chloride, of the mixture of 2' and 3' nitro-flavones, and subsequent separation of the two amines thus formed by means of the difference in solubility in water of their hydrochlorides. 19 g. of the mixture of 2' and 3' nitro-flavones were sus- pended in 250 cc. of boiling alcohol and 134 cc. of stannous chloride solution containing 24 g. of tin and 40 g. of hydrogen chloride (theory requires 24 g. of tin and 14 g. of hydrogen chloride) were added. In two minutes all had dissolved to a clear orange solution. Added 5 cc. more of the stannous chloride solution and boiled for ten minutes. On cooling, orange colored microscopic crystals came down. Allowed the mixture to stand in the ice box over night. Filtered. Dried in the air. The orange powder (34 g.) was added to two liters o^hot water and most of it dissolved leaving a gelatinous white precipitate (tin hydroxides) in suspension. The mixture was saturated with hydrogen sulfide, and the tin sulfides were re- moved by filtration. The yellow filtrate was made alkaline with dilute sodium carbonate, whereupon a yellow precipitate was formed. This was filtered, washed with water and dried over sulphuric acid. Yield=13 g. This product gave no flu- orescence in amyl alcohol or other solution which showed that 4'-amino-flavone was absent. 16 V The 13 g. of yellow substance was then suspended in 150 cc. of 5% hydrochloric acid and the mixture boiled and stirred for five minutes, whereupon some of the solid went into solu- tion. 5 cc. of concentrated hydrochloric acid were added, the boiling continued for five minutes and as soon as the mixture had cooled to room temperature, it was filtered. The precipi- tate consisted of the hydrochlorides of 2'-amino-flavone mixed with a little 3'-amino-flavone. The filtrate contained 3'-amino- flavone mixed with a considerable amount of 2'-amino-flavone. The precipitate was suspended in an excess of dilute sodium carbonate solution, heated on the water bath and stirred for fifteen minutes until the hydrochloride was completely converted to the free amine, which was filtered, washed, and dried over sulphuric acid. Yields? g. Two crystallizations from hot acetone gave thin pale yellow silky needles. Melted at 149.5-150.5 (corr.) to a yellow liquid. Subs. 0.2132: CO 2 , 0.5931; H 2 O, 0.0901. Calc. for OikHnOftN: C, 75.9% ; H, 4.6%. Found : C, 75.9% ; H, 4.7%. Subs. 0.2512: N, 13.1 cc. at 19, 765 mm. Calc. for CisHiiO 2 N: N, 5.9%. Found : N, 6.0%. Subsequent conversion of this amine, by decomposition with water of its diazonium salt, into the corresponding phenol which, in turn was converted into salicylic acid and ortho- hydroxy-anisole, proved that the amino group occupied the 2' position in the flavone nucleus. The substance gives a positive isonitrile test showing it to be a primary amine. It is slightly soluble in hot concen- trated hydrochloric acid and moderately so in the same hot dilute acid, from which on cooling, fine white silky needles precipitate. It is soluble in cold concentrated sulphuric acid, forming a colorless solution. From its solution in hot 20% sulphuric acid, on cooling, colorless straight thick bars come down. Dissolves in concentrated nitric acid, forming a yellow solution. It reduces a solution of potassium permanganate and dilute sulphuric acid in the cold. In warm dilute sul- phuric solution it gives a black amorphous precipitate with potassium dichromate. The amine is easily soluble in cold aniline, or in hot py- ridine, ethyl alcohol, methyl alcohol, acetone, glacial acetic acid, chloroform, benzene, toluene, xylene, ethyl acetate, amyl alcohol, amyl acetate or nitro-benzene. It is moderately sol- uble in hot ligroin (100-110), slightly soluble in hot ether, carbon disulfide, or carbon tetrachloride, insoluble in hot water or petroleum ether. 4'-Amino-flavone was obtained by reduction with stan- nous chloride, of the mixture of 3' and 4' nitro-flavones (above) and subsequent separation of the resulting amines by heating their hydrochlorides with water, which effected the solution 17 of the 3'-amine-hydrochloride and the precipitation of the free 4'-amine. 35 g. of the 3' and 4' nitro-flavones were suspended in 800 cc. of boiling ethyl alcohol and 246 cc. of stannous chloride solution containing 42 g. of tin and 72 g. of hydrogen chloride (theory requires 44 g. of tin and 25 g. of hydrogen chloride) were added. In five minutes all had dissolved to a dark orange solution. Added 10 cc. more of the stannous chloride mixture and after boiling further for two minutes a heavy precipitate of orange colored microscopic crystals separated. Let stand in the ice box over night. Filtered. Divided the precipitate (for convenience of manipulation of the large volumes of water used later) into three parts, and boiled each part with three and one-half liters of water for fifteen minutes. Most of the precipitate went into solution leaving a mixture of a yellow flocculent solid and a white gelatinous mass. Filtered when cool. The filtrates were saturated with hydrogen sulphide and the small amount of tin sulphide that came down was filtered off. The filtrates were made alkaline with dilute sodium car- bonate and a precipitate of small yellow needles deposited. The combined dry precipitates weighed 12 g. and consisted mainly of 3'-amino-flavone mixed with a small amount of 4'- amino-flavone. The combined precipitates (the filtrates from which de- posited 3'-amino-flavone) were heated with 100 cc. of 10% hydrochloric acid, whereupon the yellow substance dissolved leaving a white mass (stannic oxide) which was removed by filtration. The filtrate was made alkaline with dilute sodium carbonate the yellow precipitate that came down was filtered, washed, and dried over sulphuric acid. Yield=7 g. The small amount of tin oxide present in this product was removed by treating it with hot pyridine in which the amine dissolved leaving a small amount of a dark residue which was removed by filtration. The pyridine filtrate, on cooling, de- posited the amine, which, after one more crystallization from the same solvent and then another crystallization from boiling xylene, was obtained in the form of extremely long (3 cm.) golden yellow needles, which melted at 234-236 (corr.) to a yellow brown liquid. Subs. 0.2152; CO*}, 0.5979; H' 2 O, 0.0852. Calc. for CifcHnlW: C, 75.9% ; H, 4.6%. Found : C, 75.8% ; H, 4.4%. Subs. 0.3501: N, 17.7 cc. at 18, 761 mm. Calc. for CisH-nOsN: N, 5.9%. Found : N, 6.0%. The position of the amino group of this compound was determined similarly as in the case of 2'-amino-flavone. The compound gives a positive isonitrile test, showing that it is a primary amine. It is slightly soluble in hot con- centrated hydrochloric acid and moderately so in the same 18 dilute acid, from which, on cooling, small white needles de- posit. It is soluble in cold concentrated sulphuric acid (form- ing a colorless liquid). Orange needles deposit from its solu- tion in hot 20% sulphuric acid on cooling. A deep perman- ganate-purple solution results on warming the amine in alco- holic hydrochloric acid with magnesium. It reacts similarly to 2'-amino-flavone (q.v.) with potassium permanganate, po- tassium dichromate or concentrated nitric acid solutions. It is easily soluble in hot aniline, pyridine, nitro-benzene, or glacial acetic acid. It is moderately soluble in hot acetone, ethyl alcohol, methyl alcohol, chloroform, benzene, toluene, xylene, ethyl acetate, iso-amyl alcohol or amyl acetate. It is slightly soluble in hot ligroin (100-110), ether, carbon tetra- chloride or glycerol. It is insoluble in hot water, carbon disul- phide or petroleum ether. 4'-amino-flavone was found to impart an intense bluish- green fluorescence to iso-amyl alcohol, glycerol or ethyl alco- hol ; an intense blue fluorescence to ether, acetone, ethyl ace- tate, amyl acetate or pyridine; a faint green fluorescence to methyl alcohol or phenol. No fluorescence was observed in solutions of the amine in chloroform, benzene, toluene, xylene, ligroin, carbon tetrachloride or glacial acetic acid. An inspection of the above solvents (excluding pyridine) shows that those which give rise to the fluorescence contain the alcohol hydroxyl group (the ethyl acetate, amyl acetate, ether and acetone used, were of the ordinary "C. P." quality and so all contained impurities of alcohol; i. e., ethyl alcohol in ethyl acetate and in ether ; amyl alcohol in amyl acetate ; and methyl alcohol in acetone). Unlike these solvents, ligroin, benzene, toluene, xylene, chloroform, glacial acetic acid or carbon tetrachloride contain no impurities of an alcoholic nature. In order to more definitely confirm the relationship be- tween the presence of the alcohol group and the production of fluorescence with 4'-amino-flavone, some of the amine was dissolved in specially prepared pure ether * (alcohol and water free), with the surprising result that no trace of fluorescence was apparent. However, when a drop of ethyl alcohol was added to this ether solution an intense blue fluorescence im- mediately appeared. Likewise, when a drop of water was added to a solution of the amine in the pure ether, an intense blue fluorescence appeared this makes it seem that the hydroxyl group of water as well as that from an alcohol will cause the fluorescence. The failure of solvents like ligroin, benzene, etc., to pro- duce fluorescence with the amine seems anomalous at first, * The author is indebted to Prof. J. M. Nelson, from whom this ether was obtained. It was used by Prof. Nelson in his work on "Electro- motive Force in Non-Aqueous Solvents." 14 19 in view of the fact that these solvents contain some water. But the following experiment seems to show that a rather high concentration of hydroxyl radical is necessary to produce the fluorescence : to 5 cc. of hot benzene was added an excess of 4'-amino-flavone. To this hot mixture was added, drop by drop, iso-amyl-alcohol ; when a drop of the alcohol came in contact with the surface of the benzene solution, an intense blue fluorescence was formed at that place, but on shaking the mixture the fluorescence disappeared. It was only when 0.5 cc. of the alcohol had been added that the fluorescence became permanent. The failure, then, of solvents like ligroin, benzene, etc., to produce fluorescence with the amine, may be due to their not containing enough water. No fluorescence is observed with the 4' amino-flavone in water, presumably because the amine is insoluble in water, cold or hot. The amine does not fluoresce in glacial acetic acid, or in glacial acetic acid to which has been added water (not enough to cause the amine to precipitate) most likely because of the action of the acetic acid in neutralizing the amino group, the presence of which in the free condition, only, causes the fluorescence. The presence of fluorescence in a pyridine solution of the amine is doubtless due to the water present in this solvent. Another peculiar property of this amine is that it dissolves in some solvents with the formation of yellow solutions and in others forming colorless solutions : yellow in ethyl alcohol, methyl alcohol, ethyl acetate or glacial acetic acid ; colorless in benzene, toluene, xylene, ligroin (100-110) chloroform, carbon tetrachloride, iso-amyl alcohol or amyl acetate. Light yellow colors on wool and silk were obtained by impregnating these fibres with a hot solution of the 4'-amino- flavone hydrochloride in the presence of an excess of hydro- chloric acid, and then developing the color in dilute sodium carbonate solution. 3 '-Amino-flavone was obtained pure by recrystallization, from pyridine, of the yellow product that was precipitated by neutralization of the filtrate from the precipitate of 4'-amino- flavone (above). 12 g. of the crude amine (M.P. 144-149.5) were recrys- tallized twice from pyridine and then once from xylene lemon- yellow straight needles were obtained. Melted 156-157 (corr.) to a yellow liquid. Yield=8 g. Subs. 0.2410: CO 2 , 0.7068; H 2 O, 0.0997. Calc. for CifeH'nOaN: C, 79.9% ; H, 4.6%. Found : C, 80.0% ; H, 4.6%. Subs. 0.3101: N, 16.8 cc. at 20, 749 mm. Calc. for Ci 5 HiiO 2 N: N, 5.9%. Found: N, 6.1%. The position of the amino group of this compound was determined similarly as with 2'-amino-flavone. 20 The compound gives a positive isonitrile test, thus show- ing it to be a primary amine. It is somewhat soluble in con- centrated hydrochloric acid and easily so in hot dilute hydro- chloric acid from which, on cooling, it precipitates as fine white silky needles. It is soluble in concentrated sulphuric acid (forming a colorless solution) ; its solution in hot dilute sulphuric acid (20%), on cooling, deposits white needles. It reacts similarly to 2'-amino-flavone (q.v.) with potassium permanganate, po- tassium dichromate or concentrated nitric acid solutions. It is easily soluble in cold aniline or acetone ; in hot glacial acetic acid or nitro-benzene. Is moderately soluble in hot ethyl alcohol, chloroform, benzene, toluene, xylene, ethyl ace- tate, amyl alcohol or amyl acetate. Is slightly soluble in hot ligroin (100-110), ether, carbon disulfide or carbon tetra- chloride. Is insoluble in hot water, or petroleum ether. Light yellow colors were obtained from this amine on wool and silk, by using a similar procedure to that outlined above for 4'-ammo-flavone. 2'-Diacetyl-amino-flavone 1 g. of 2'-amino-flavone was added to 10 cc. of acetic anhydride. In one minute the yellow amine was converted to a white solid, which dissolved on the application of heat. The solution was boiled for five hours. At the end of this time, most of the acetic anhydride was evaporated at the boiling point, and the rest at room tem- perature with a current of air. The solid that remained was recrystallized twice from ethyl alcohol. Small shining white oblong prisms were obtained. M.P. 186.5-187.5 (corr.). Yield:=0.9 g. Subs. 0.2411: N, 9.5 cc. at 18, 756 mm. Calc. for CwHisOiN: N, 4.4%. Found : N, 4.5%. The compound is readily soluble in hot acetone, chloro- form, glacial acetic acid or acetic anhydride. Is moderately soluble in hot ethyl alcohol or benzene. Is slightly soluble in hot ether, and insoluble in hot petroleum ether, carbon disul- fide, carbon tetrachloride or ligroin (100-110). Dissolves in concentrated sulphuric acid, forming a colorless solution. 3'-Diacetyl-amino-flavone. 1 g. of 3'-amino-flavone was carried through a similar treatment with acetic anhydride (as above). The solid that remained after evaporation of the acetic anhydride was recrystallized thrice from hot acetone. Delicate small hair-like white needles were obtained. M.P. 231-232 (corr.). Yield=0.8 g. Subs. 0.2612: N, 10.3 cc. at 17, 768 mm. Calc. for C^Hi 5 O 4 N: N, 4.4%. Found: N, 4.6%. The compound is easily soluble in hot ethyl alcohol or glacial acetic acid. Is moderately soluble in hot benzene, 21 toluene, or ethyl acetate. Dissolves in cold concentrated sul- phuric acid, forming a colorless solution. 4'-Diacetyl-amino-flavone. 1 g. of 4'-amino-flavone was treated with acetic anhydride, as above. The solid residue, remaining from the evaporation of the acetic anhydride, was crystallized once from dilute ethyl alcohol, and balls of micro- scopic crystals came down which, when dried, melted 175- 222, thus showing the product to be a mixture. This product was dissolved in 10 cc. of acetic anhydride and the solution boiled again for five hours. The acetic anhydride was re- moved by evaporation, and the solid residue was recrystallized thrice from dilute ethyl alcohol. Small hair-like white needles were obtained. M.P. 246-248 (corr.). Yield=0.65 g. Subs. 0.2112: N, 8.4 cc. at 15, 751 mm. Calc. for CifcHisCUN: N, 4.4%. Found : N. 4.6%. The compound is readily soluble in cold ethyl alcohol or glacial acetic acid. Is moderately soluble in hot benzene, toluene, xylene or ethyl acetate. Dissolves in cold concen- trated sulphuric acid, forming a colorless solution. 2'-Hydroxy-flavone was synthesized by the decomposi- tion, in water solution, of the diazonium salt derived from 2'-amino-flavone, and is the sixth of the eight possible mono- hydroxy-flavones to be isolated, the other five having first * a different method than that used by Kostanecki. been synthesized by Kostanecki. 8 3.5 g. of 2'-amino-flavone were heated with 20 cc. of con- centrated hydrochloric acid in 150 cc. of water. To the mix- ture at 5 were added 8.4 cc. of sodium nitrite solution con- taining 1 g. of sodium nitrite (calculated amount). After stirring for one-half hour the amine hydrochloride had entirely dissolved. Boiled the solution for ten minutes (the diazo salt decomposes slowly below the boiling point). At the end of this time nitrogen ceased to be evolved. Cooled, and filtered the slightly colored flocculent precipitate. Washed with water. On stirring in 200 cc. of 1% aqueous sodium hydroxide, the precipitate dissolved, leaving a small amount of a brown solid which was removed by filtration. The yellow filtrate on acidifi- cation with dilute hydrochloric acid, gave a white flocculent precipitate. This was washed with water, and recrystallized thrice from alcohol. Shining white plates were obtained. M.P. 249-250 (corr.). Yield=2.2 g. Subs. 0.2101: C0 2 , 0.5828; HA 0.0816. Calc. for C^H^O*: C, 75.6% ; H, 4.2%. Found : C, 75.7% ; H, 4.3%. Subsequent conversion of this hydroxy-flavone into salicy- lic acid and ortho-hydroxy-anisole (q.v.), proved the hydroxyl group to occupy the 2' position in the flavone nucleus. *Two of these five have been also synthesized in this work (q. v.) by 22 The compound dissolves slowly in cold concentrated sul- phuric acid forming a greenish yellow solution with a slight green fluorescence. It is soluble in cold dilute or hot con- centrated aqueous sodium hydroxide from the latter solution, on cooling, small yellow needles are deposited. It is readily soluble in hot glacial acetic acid. Is mod- erately soluble in hot acetone, chloroform, ethyl acetate, amyl acetate, ethyl alcohol, xylene or toluene. Is slightly 'soluble in hot ether or benzene. 3'-Hydroxy-flavone * was prepared in similar manner to 2'-hydroxy-flavone (in the previous experiment). The crude hydroxy-flavone was recrystallized twice from ethyl alcohol. From 4 g. of 3'-amino-flavone were obtained 2.5 g. of shining white narrow plates. M.P. 207-208 (corr.). St. v. Kostan- ecki gives 208. Subs. 0.1762: CO 2 , 0.4894; H 2 O, 0.0650. Calc. for Ci 5 Hi O 3 : C, 75.6%; H, 4.2%. Found: C, 75.8%; H, 4.1%. Subsequent conversion of this hydroxy-flavone (q.v.) to meta-hydroxy-benzoic acid and ortho-hydroxy-anisole, con- firmed the position of the hydroxyl group in the flavone nu- cleus as assigned to it above. The compound is soluble in cold dilute or hot concentrated aqueous sodium hydroxide from the latter solution, on cool- ing, yellow needles are deposited. 4'-Hydroxy-flavone * was prepared in similar manner to 2' and 3'-hydroxy-flavones (above). The crude hydroxy- flavone was recrystallized thrice from a mixture of pyridine and alcohol. Small white needles were obtained. M.P. 269- 270 (corr.). St. v. Kostanecki gives M.P. 268. Yield=2.1 g. from 4 g. of 4'-amino-flavone. Subs. 0.1523: CO 2 , 0.4212; H, 0.0594. Calc. for C^HioOs: C, 75.6%; H, 4.2%. Found: C, 75.5%; H, 4.4%. The compound dissolves in cold concentrated sulphuric acid, forming a yellow solution with a green fluorescence which, on long standing of the solution, changes to a bluish fluorescence. Subsequent conversion of this hydroxy-flavone into para- hydroxy-benzoic acid and ortho-hydroxy-anisole (q.v.) con- firmed the position of the hydroxyl group on the flavone nu- cleus as assigned to it above. 2'-Acetoxy-flavone. 0.5 g. of 2'-hydroxy-flavone, 1 g. of anhydrous sodium acetate, and 5 cc. of acetic anhydride were heated to boiling for one-half hour. 5 cc. of water were added, and the mixture was warmed on the water bath, to hydrolyze the excess of acetic anhydride. 10 cc. more of water were added to dissolve the sodium acetate the oil, which had sepa- * These hydroxy-flavones were first synthesized by St. v. Kostanecki by another method than the one used here 8 . 23 rated, after remaining in the ice-box over night, changed to a crystalline solid. Filtered, washed with water, and recrys- tallized twice from dilute alcohol. Long thin white needles were obtained. M.P. 88.5-89 (corn). Yield=0.4 g. Subs. 0.2131: CO 2 , 0.5703; H 2 O, 0.0838. Calc. for Ci 7 Hi 2 O4: C, 72.9%; H, 4.3%. Found: C, 73.0%; H, 4.4%. The compound is soluble in cold glacial acetic acid, ethyl acetate, benzene or acetic anhydride. Is somewhat soluble in hot ligroin (100-110). 3'-Acetoxy-flavone was prepared as directed by St. v. Kostanecki, by heating 3'-hydroxy-flavone with acetic anhy- dride and anhydrous sodium acetate. 5 Long colorless needles were obtained by two crystallizations from dilute alcohol. M.P. 97-98 (corr.). St. v. Kostanecki gives 97. 0.5 g. of the phenol gave 0.3 g. of the acetyl derivative. Subs. 0.1857: CO 2 , 0.4956; H 2 O, 0.0747. Calc. for Ci 7 HioO 4 : C, 72.9%; H, 4.3%. Found: C, 72.8%; H, 4.5%. 4'-Acetoxy-flavone was obtained from 4'-hydroxy-flavone with acetic anhydride and sodium acetate as directed by St. v. Kostanecki. 4 White needles were obtained by two recrys- tallizations from dilute alcohol. M.P. 136 (corr.). St. v. Kostanecki gives 137. 0.5 g. of the phenol gave 0.35 g. of the acetyl derivative. Subs. 0.1023: CO 2 , 0.2738; H 2 O, 0.0411. Calc. for diK^O*: C, 72.9% ; H, 4.3%. Found : C, 73.0% ; H, 4.5%. The conversion of 2'-hydroxy-flavone into salicylic acid and ortho-hydroxy-anisple. St. v. Kostanecki found that when an hydroxy-flavone derivative is heated with sodium ethoxide, the pyrone ring splits at the double bond and at the ether oxygen with the formation of an ortho-hydroxy-anisole, and a benzoic acid derivative.* 7 When 2'-hydroxy-flavone was treated with sodium eth- oxide, it yielded salicylic acid and ortho-hydroxy-anisole thus proving that the hydroxyl group occupies the 2' position in the flavone nucleus. 1.3 g. of 2'-hydroxy-flavone were added to 2.3 g. of sodium dissolved in 40 cc. of ethyl alcohol and the solution was boiled under a reflux condenser for two hours. The mixture was steam distilled to remove the alcohol. It was then acidified with a slight excess of hydrochloric acid and steam distilled again, until no more oil came over (which was the case after ten minutes). 10 cc. of concentrated hydrochloric acid were added to the hot solution (in the distilling flask) which, on cooling, deposited long white needles. After another crys- tallization from hot water these white needles melted at 156- 157 (corr.). Yield=0.5 g. This compound responded to the * See equation III. 24 tests for salicylic acid with ferric chloride, bromine water or methyl alcohol and concentrated sulphuric acid. The pale yellow oil present in the distillate (above) was extracted with ether. The ether layer was separated and treated with dilute sodium carbonate in order to remove the small amount of salicylic acid that had come over with the steam. The ether, after evaporation left a pale yellow oil (of a characteristic aromatic odor), which gave an intense violet color with ferric chloride. This oil was proven, by conversion to its phenyl hydrazone, to be ortho-hydroxy-anisole : To a solution of the oil in 5 cc. of glacial acetic acid was added 0.7 g. of phenyl hydrazine in 3 cc. of glacial acetic acid. The mixture was warmed for ten minutes. On the addition of 5 cc. of water, a white precipitate came down. This was filtered and recrystallized once from dilute alcohol. Small, fine, shining white needles were obtained. M.P. 108-108.5 (corn). Tahara 16 gives 108. Subs. 0.2512: N, 27.3 cc. at 17, 754 mm. Calc. for Oi4Hi 4 ON 2 : N, 12.4%. Found: N, 12.5%. The conversion of 3'-hydroxy-flavone into meta-hydroxy- benzoic acid and ortho-hydroxy-anisole was accomplished with sodium ethoxide and ethyl alcohol (as above). The meta- hydroxy-benzoic acid formed melted at 199-200 (corr.). The ortho-hydroxy-anisole was identified by converting it to its phenyl-hydrazone (as above) M.P. 108-108.5 (corr.). The conversion of 4'-hydroxy~flavone into ortho-hydroxy- anisole and para-hydroxy-benzoic acid was accomplished with sodium ethoxide and ethyl alcohol (as above). The para-hydroxy-benzoic acid formed melted at 208-209 (corr.). The ortho-hydroxy-anisole was identified by converting it to its phenyl-hydrazone (as above). M.P. 108-108.5 (corr.). Flavone (2')-azo-beta-naphthol 1.5 g. of 2'-amino-flavone were heated for ten minutes with 3 cc. of concentrated hydro- chloric acid in 50 cc. of water, in order to convert it to the hydrochloride. To this mixture at 0-5, were added 3.6 cc. of sodium nitrite solution containing 0.45 g. of sodium nitrite (calculated amount). After stirring for one-half hour, the amine-salt had completely dissolved. The resulting diazo-salt solution was added to 0.9 g. (calculated amount) of beta- naphthol dissolved in 25 cc. of 3 N aqueous sodium hydroxide, at 0-5. The flocculent red precipitate was filtered and well washed with water. The moist substance was crystallized once from glacial acetic acid, and tufts of hair-like red-orange needles were obtained, which melted, with decomposition, at 265-266.5 (corr.) to a dark red liquid. Yield=2.0 g. Subs. 0.3101: N, 19.6 cc. at 18, 761 mm. Calc. for QHi' 6 O 3 N 2 : N, 7.1%. Found : N, 7.3%. The compound dissolves in cold concentrated sulphuric acid forming a reddish purple solution. Is readily soluble in 25 hot concentrated hydrochloric acid, and slightly so in cold concentrated hydrochloric acid or nitric acid, forming cherry- red solutions. Is insoluble in hot or cold dilute or concen- trated aqueous sodium hydroxide. Is moderately soluble (forming orange-red solutions) in hot glacial acetic acid, ethyl alcohol, benzene, or acetic anhydride. Is easily soluble in hot amyl alcohol (technical) or chloroform. Is slightly soluble in ligroin ; and insoluble in cold or boiling water. Flavone (2')-azo-beta-naphthol is assumed to possess the usual ortho-quinone-imide configuration (with the nitrogen attached to the naphthalene ring on the alpha-1 position) which results on coupling a diazonium salt with beta-naphthol. (See structure II.) The two isomers of this compound, which are described below, are assumed to have similar configurations. (See structures III and IV.) Flavone (3 ')-azo-beta-naphthol. 1.5 g. of 3'-amino-flavone were carried thru a procedure similar to that described in the previous experiment. The flocculent red precipitate resulting was crystallized once from glacial acetic acid. Small, flat, shining crimson prisms were obtained. The compound assumed a metallic lustre at 253 and melted, with decomposi- tion at 257 (corr.) to a dark red liquid. Yield=:2.1 g. Subs. 0.2781: N. 17.6 cc. at 19, 755 mm. Calc. for CasHieOs^: N, 7.1%. Found: N, 7.2%. The compound dissolves in cold concentrated sulphuric acid, forming a deep wine-red solution. Is readily soluble in hot concentrated hydrochloric acid, and slightly so in cold concentrated hydrochloric or nitric acid, forming cherry-red solutions ; insoluble in hot or cold, dilute or concentrated aqueous sodium hydroxide. Is moderately soluble in hot glac- ial acetic acid or acetic anhydride; also slightly soluble in hot ethyl alcohol, benzene, chloroform, amyl alcohol or ligroin (100-110) ; and insoluble in cold or boiling water. Flavone (4')-azo-beta-naphthol. Proceeding as above, 1.5 g. of 4'-amino-flavone gave a dark red flocculent precipitate which was crystallized once from glacial acetic acid. Radiat- ing masses of small dark red needles were obtained which melted, 'with decomposition, at 274-275 (corr.) to a dark red liquid. Yield=2.0 g. Subs. 0.3112: N, 19.4 cc. at 17, 765 mm. Calc. for C 25 Hi 6 O 3 N2: N, 7.1%. Found: N, 7.2%. The compound dissolves in cold concentrated sulphuric acid, forming a deep purple solution. Is readily soluble in hot concentrated hydrochloric acid, and slightly so in cold con- centrated hydrochloric or nitric acid, forming deep purple solu- tions. Is insoluble in cold or hot, dilute or concentrated aqueous sodium hydroxide. Is easily soluble (forming a dark red solution) in hot chloroform or amyl alcohol (technical). Is moderately soluble in hot benzene or acetic anhydride ; also 26 slightly soluble in hot ethyl alcohol or ligroin (100-110) ; and insoluble in cold or boiling water. Application of the Flavone-azo-beta-naphthol dyes to silk, wool and cotton. Silk, wool and cotton skeins were dyed by developing the colors directly on the fibre. Good results were obtained with silk and wool, but the cotton, even when pre- viously impregnated with Turkey Red Oil, in all cases took the dyes unevenly. Inferior shades were obtained by passing the skeins first thru a solution of the diazo salt and then thru an alkaline beta- naphthol bath. But when the order was reversed and the goods impregnated first with the alkaline beta-naphthol solu- tion and then passed thru the diazo-salt bath in which the hydrogen, ion concentration from the excess of hydrochloric acid had been reduced by the addition of sodium acetate, 18 good dyeings were obtained. From flavone (2')-azo-beta-naphthol, a bright orange color was obtained on silk, and a duller shade of orange on wool. Similar colors on silk and wool were obtained with flavone (3')-azo-beta-naphthol. With flavone (4')-azo-beta-naphthol, however, a bright red color was formed on silk and a less bright red shade on wool. The fastness to light of the dyed materials was determined by exposing them in the north window of the laboratory. After a month's exposure (up to the time of this writing), a comparison with some of the unexposed dyed materials showed that no change in shade had been effected in any case. The dyed silk and wool samples were found to be very resistant to the action of the alkali, the shades not being af- fected by hot soap solution or 3% aqueous sodium carbonate. In all cases, however, a 2% acetic acid solution caused a dullening in the shades. The "exhaustion" of the diazo baths was more rapid with wool than with silk. It was found that when a number of skeins of silk of equal weight, impregnated with alkaline beta- naphthol, were successively worked in the same solution of diazo salt (which initially contained 5% of diazo salt on the weight of one skein of silk), the second sample possessed a slightly less bright shade than the first; the third, however, was very much lighter in shade than the first two. In the case of wool samples, which were treated in a similar manner, there was as great a difference between the shades of the first and second samples as between the first and third dyeings on silk. III. Beta-brom-hydrocinnamic acid. C 6 H 5 .CHBr.CH 2 ,COOH. was prepared as described by Anschutz 17 , by the interaction 27 of cinnamic acid and hydrogen bromide in glacial acetic acid. Two crystallizations of the crude product from benzene, gave white shining plates. M.P. 133-135 (rate of heating was 5 degrees per minute). Methyl-beta-brom-cinnamate C 6 H 5 CHBr.CH 2 .COOCH 3 This ester, which has not been prepared before, was syn- thesized for use in a reaction carried out in connection with the synthesis of beta-phenoxy-hydrocinnamic acid (q.v.). It was obtained by the esterification, with dry hydrogen bromide and ethyl alcohol, of beta-brom-hydrocinnamic acid. 50 g. of beta-brom-hydrocinnamic acid were dissolved in 125 cc. of methyl alcohol, and the resulting solution was satu- rated with dry hydrogen bromide gas at room temperature. After standing over night, the mixture was poured into ice water. The faint yellow oil that separated was extracted with petroleum ether and the ether layer was mixed with anhydrous calcium chloride and calcium carbonate and allowed to stand over night. After filtering, half of the petroleum ether was evaporated, and the remaining solution, after stand- ing in the ice box for a few hours, deposited large colorless thick prisms. M.P. 37.5-38.5 (corr.). Yield=33 g. Subs. 0.3114: AgBr, 0.2399. Calc. for Ci HiiO 2 Br: Br, 32.9%. Found: Br, 32.8%. The compound is very soluble in cold chloroform, benzene, carbon disulfide, carbon tetrachloride, glacial acetic acid, tolu- ene, ether or acetone. It is moderately soluble in cold pe- troleum ether, ethyl ether, or ligroin (100-110). Beta-phenoxy-hydrocinnamic acid C 6 H 5 CH(OC 6 H 5 ).CH 2 . COOH was synthesized by the action of phenol on beta- brom-hydrocinnamic acid. Two other products, beta-phenyl-hydrocoumarin and beta- para-hydroxy-phenyl-hydrocinnamic acid were also formed in this reaction. The latter two compounds have been previously synthesized by the reaction of phenol and allo-cinnamic acid 13 . 30 g. of beta-brom-hydrocinnamic acid were added to a solution of 13 g. dry phenol (calculated amount=12.3 g.) in 50 cc. of dry benzene. The mixture was heated and the acid dissolved. The temperature of the solution was maintained at 85-90 for two hours until the evolution of hydrogen bromide had slackened. A small amount of water had col- lected below the cherry-red benzene layer. On cooling, the benzene solution deposited a white precipitate. This was filtered, washed twice with cold benzene and dried in the air. The product smelled strongly of phenol. It weighed 12 g. Two crystallizations from benzene gave 10.4 g. of matted long white silky needles. M.P. 150-151 (corr.). Yields 33% of the amount calculated from the beta-brom-hydrocin- namic acid. 28 Subs. 0.1424: CO 2 , 0.3880; H 2 O, 0.0770. Calc. for Ci 5 Hi 4 O 3 : C, 74.470; H, 5.8%. Found: C, 74.2%; H, 6.0%. The compound is soluble in dilute sodium carbonate solu- tion. It does not contain a double bond as is proven by its inability to decolorize, in the cold, potassium permanganate. It does not respond to any of the tests for the phenolic hydroxyl group. It does not contain bromine. The empirical formula of the compound, its properties, and its method of formation prove it to be beta-phenoxy-hydro- cinnamic acid. Precipitates were formed on the addition of a solution of the ammonium salt of beta-phenoxy-hydrocinnamic acid to solutions of the nitrates of each of the following metals re- spectively; cadmium, copper (cupric), lead and silver. No precipitates were formed with the following metals : sodium, potassium, calcium, barium, bismuth, cobalt or iron (ferric). The isolation of beta-para-hydroxy-phenyl-hydrocinnamic acid The benzene filtrate from the precipitate of beta-phe- noxy-hydrocinnamic acid (above) was steam distilled and a mixture of benzene and phenol came over. The phenol was isolated from the distillate by separating the benzene from the water layer, extracting the water layer with ether, combining the benzene and ether layers, extracting the benzene-ether solution with aqueous sodium carbonate (to remove some free acid), drying the ether-benzene solution with calcium chloride, filtering, evaporating off the ether and benzene, and finally distilling the yellow oil remaining. 1.5 g. of phenol, distilling at 185-187, were thus obtained. This amount is 0.8 g. more than the excess of phenol which was used in the above reaction thus showing that the reaction had not been complete with regard to the phenol. The brown viscous oil in the distilling flask was dissolved in ether and extracted with dilute sodium carbonate until no more carbon dioxide was evolved. The water layer was sepa- rated and on acidification with dilute hydrochloric acid, a white precipitate came down. Some of this white precipitate, dissolved in aqueous so- dium carbonate, reduced permanganate solution with the pro- duction of an odor of benzaldehyde, which indicated the pres- ence of cinnamic acid (this was doubtless formed by decomposi- tion of part of the beta-brom-hydrocinnamic acid into cinnamic acid and hydrogen bromide in the above phenol and beta- brom-hydrocinnamic reaction). The white precipitate how- ever, contained another substance which was separated in pure form from the cinnamic acid by four recrystallizations from toluene. 1.4 g. of white needles were obtained. M.P. 151.5- 152.5 (corr.). A mixture of the compound with beta-phe- noxy-hydrocinnamic acid, melted at 117-126, which proved that it was not beta-phenoxy-hydrocinnamic acid. 29 Subs. 0.2561: CGfc, 0.6975; H*O, 0.1373. Calc. for CisH^Os: C, 74.4%; H, 5.8%. Found: C, 74.3%; H, 6.0%. The compound is soluble in aqueous sodium carbonate. It responds to tests for the phenolic hydroxyl group with con- centrated sulphuric acid and sodium nitrite, and with titanium dioxide in concentrated sulphuric acid. It does not, however, give a color reaction with ferric chloride. It contains no bromine. The compound is believed to be identical with beta-para- hydroxy-phenyl-hydrocinnamic acid, which was previously iso- lated by Liebermann 13 , and with which it agrees in its em- pirical formula and properties. A solution of the ammonium salt of beta-para-hydroxy- phenyl-hydrocinnamic acid, produced precipitates when added to solutions of the nitrates of each of the following metals, respectively : cadmium, cobalt, lead or silver. No precipitate was formed with sodium, potassium, calcium, barium, bismuth, copper (cupric) or iron (ferric). The formation in the above reaction, of beta-para-hydroxy- phenyl-hydrocinnamic acid, may be regarded as a simple metathesis between phenol and beta-brom-hydrocinnamic acid, thru the para hydrogen atom of phenol and the bromine atom of the acid *. Isolation of beta-phenyl-hydrocoumarin. The ether layer, from which the beta-para-hydroxy-phenyl-hydrocinnamic and cinnamic acids were extracted with sodium carbonate (above), was evaporated and a yellow oil remained which, on stirring, solidified to a crystalline mass (12 g.). Two crystallizations from alcohol gave thick, white, shining needles. M.P. 81.5- 82 (corr.). Yield=8.2 g. Subs. 0.1550: CO 2 , 0.4642; H 2 O, 0.0873. Calc. for Ci' 5 Hi 2 O 2 : C, 81.6%; H, 6.3%. Found: C, 81.7%; H, 6.3%. The compound is insoluble in cold aqueous sodium car- bonate, and only partially so in the same boiling solvent. It is insoluble in cold, and easily soluble in hot dilute sodium hydroxide solution. On acidification of the sodium hydroxide solution, a white precipitate comes down. This white precipi- tate is soluble in cold sodium carbonate solution. The compound distills at 243 (uncorr.) at 40 mm. pres- sure. Liebermann gives 237 (uncorr.) at 30 mm. The color- less oil that comes over quickly solidifies in the condenser tube as white needles. M.P. 81-81.5 (corr.). The compound is believed to be identical with beta- phenyl-hydrocoumarin, which was first isolated by Lieber- mann 13 , and with which it agrees in its empirical formula and properties. * See equation IV. 30 The formation, in the above reaction, of beta-phenyl-hy- drocoumarin may be regarded as proceeding by the initial methathesis between phenol and beta-brom-hydrocinnamic acid, thru the ortho hydrogen atom of phenol and the bromine atom of the acid, to form an intermediate compound, beta- ortho-hydroxy-phenyl-hydrocinnamic acid, which immediately condenses to form beta-phenyl-hydrocoumarin with elimina- tion of water.* The observed formation of water in the above reaction is in accord with this explanation. Comments In an attempt to obtain a better yield of beta- phenoxy-hydrocinnamic acid, phenol was heated with methyl beta-brom-hydro-cinnamate ; but the greater part of the phenol was recovered unchanged, and most of the methyl-brom-hy- drocinnamate was found to have decomposed into methyl cin- namate and hydrogen bromide. Only a small amount of beta- phenoxy-hydrocinnamic acid (isolated by the saponification of its methyl ester which was formed) was obtained. Beta-brom-hydrocinnamic acid when treated with potas- sium phenolate gave only cinnamic acid and styrol. The barium salt of a disulfonic acid of beta-phenoxy-hy- drocinnamic acid. [C 6 H 3 (SO 3 ) 2 .CH(OC 6 H 5 ).CH 2 .COO] 2 Ba 3 . 5.5H 2 O. It was considered probable that beta-phenoxy- hydrocinnamic acid, by the dehydrating action of concentrated sulphuric acid, would be converted into flavanone.** It was found, however, that a disulfonic acid derivative of beta-phe- noxy-hydrocinnamic acid was formed instead. This disulfonic acid was isolated in the form of its hydrated barium salt. 6.7 g. of beta-phenoxy-hydrocinnamic acid were added to 60 g. of concentrated sulphuric acid, heated to 130-135, and immediately dissolved with the formation of a pale yellow solution. The mixture was maintained at the above tempera- ture for one minute (no odor of sulphur dioxide was per- ceptible) and then poured into ice. Added 120 g. of solid barium carbonate (calculated amount for 60 g. of sulphuric acid) and filtered the neutral solution. Evaporated the filtrate to dryness. Extracted the yellow solid residue with hot alco- hol. The alcohol dissolved the yellow impurity, leaving a white crystalline solid. The alcohol solution was evaporated and a slight amount of a yellow oil was left. This oil was very soluble in water, gave an intense purple color with ferric chloride, reduced potassium permanganate in the cold, and gave a purple color in hot aqueous sodium hydroxide. Not enough of the oil was available for further investigation. The white barium salt, after the above alcohol treatment, was recrystallized three times from water and ethyl alcohol. * See equation V. ** According to equation I. 31 A white flocculent precipitate was obtained. Under the micro- scope this precipitate was seen to consist of thin broad ir- regular plates. The precipitate was filtered and dried over sulphuric acid. Yield=4 g. Subs. 0.4600: H^O lost at 100-110, 0.0352; BaSO 4 02461 Calc for QjoH22Oi8S 4 Ba3.5.5H2O : H 2 O, 7.57%. Found : H