EXCHANGE 
 
29 
 
 [Reprinted from the Journal of the American Chemical Society, 
 Vol. XLIII. No. 12. December, 1921.J 
 
 Researches on Pyrimidines* XCL Alkyla- 
 tion of 2-Mercapto-Pyrimidines 
 
 By William J. Horn 
 
* 
 
 
 IReprinted from the Journal of The American Chemical Society, 
 Vol. XLIII. No. 12. December, 1921.] 
 
 [CONTRIBUTION FROM THE DEPARTMENT OF CHEMISTRY, YALE UNIVERSITY. ] 
 RESEARCHES ON PYRIMIDINES. XCI. ALKYLATION OF 2- 
 MERCAPTO-PYRIMIDINES. 
 
 BY WlU<IAM J. HORN. 1 
 Received July 28, 1921. 
 
 When a 2-mercapto-6-oxypyrimidine combination is subjected to alky- 
 lation in alkaline solution, it is susceptible to attack in three different 
 positions and, at the present time, we have no law, or rule, which will 
 permit one to predict the configuration most likely to be formed. 
 
 NH CO 
 
 I I 
 RSC CH 
 
 II II 
 N CH 
 
 In most of the cases so far examined 2 where the radical, R, of the 2-mer- 
 
 1 This paper was constructed from a dissertation presented by William John Horn 
 to the Faculty of the Graduate School of Yale University, in June, 1921, in candidacy 
 for the degree of Doctor of Philosophy. (T. B. Johnson). 
 
 1 Johnson and Clapp, J. Biol. Chem., 5, 51 (1908) ; Johnson and Heyl, Am. Chem. J., 
 37, 628 (1907); Wheeler and Johnson, ibid., 42, 30 (1909); Johnson and Jones, ibid., 
 40, 538 (1908); Johnson and Derby, ibid., 40, 444 (1908); Wheeler and McFarland, 
 ibid. t 42, 101 (1909); Wheeler and Liddle, THIS JOURNAL, 30, 1152 (1908); Johnson and 
 Zee, Am. Chem. J., 49, 287 (1913). 
 
2604 WIU,IAM J. HORN. 
 
 capto group has been strongly positive in nature, the alkylation reactions 
 have been productive quite generally of isomeric 1- and 3-nitrogen sub- 
 stituted pyrimidines, and there seems to be no regularity in the proportion 
 in which such isomers are produced. Regarding the mechanism of these 
 reactions we have no very positive evidence, but it has been assumed 
 as very probable, that all these changes take place primarily by addition 
 of the alkyl halide to the sodium salt of the pyrimidine, which is followed 
 by dissociation of the resulting polymolecular combination giving the al- 
 kylated pyrimidine as the final product of reaction. The configuration 
 obtained will depend entirely upon the constitution of the primary ad- 
 dition product. 
 
 In some cases, however, it has been observed, 3 ' 4 especially when the 
 radical R of the 2-mercapto group is negative in character, that the pro- 
 duct of alkylation is not a nitrogen pyrimidine derivative, but one in which 
 the substitution of the alkyl group has taken place on oxygen in the 6- 
 position of the pyrimidine cycle with formation of an alkoxyl or imido 
 ester combination. Such transformations may be interpreted as taking 
 place through direct substitution, although it is not improbable that the 
 addition theory of reaction may apply also in these cases. In fact, the 
 results obtained by Johnson and Moran 4 on pyrimidine alkylations, 
 where alcoholysis of imido ester combinations was observed to take place, 
 would seem to be very strong evidence in support of the fact that we have 
 to deal with intermediate addition products in this type of change also. 
 
 We now describe in this paper another series of alkylation experiments 
 which have revealed further abnormalities in chemical behavior during 
 the process of alkylation. We have substituted the negative radical, 
 ^-nitrobenzyl, NOsCeHiCHs for R and synthesized the mercapto-pyri- 
 midine represented by Formula I. This compound is easily prepared 
 by the action of ^-nitrobenzyl chloride on the sodium salt of 2-thio-4- 
 methyluracil. 
 
 Alkylation of this 2-mercapto-pyrimidine (I) with methyl iodide leads 
 to the formation of two products which are not isomeric. The data thus 
 far obtained indicate that the methyl group substitutes in methyl alcohol 
 solution to give only one product, namely, l,4-dimethyl-2--nitroben- 
 zyl-mercapto-6-oxypyrimidine, (V). The structure of this compound 
 was established by its behavior on hydrolysis when it was found to be 
 transformed smoothly into ^-nitrobenzyl mercaptan (VII) and l,4~di- 
 methyluracil (VI). We obtained no evidence of the formation of an 
 isomeric, 3,4-dimethyl-2--nitrobenzyl-mercapto-6-oxypyrimidine or an 
 imido ester combination resulting from substitution on oxygen in the 6- 
 position of the ring. 
 
 1 Johnson and Haggard, THIS JOURNAL, 37, 177 (1915). 
 4 Johnson and Moran, ibid., 37, 2591 (1915). 
 
AI,KYI.ATION OF MBRCAPTO-PYRIMIDINES. 
 
 2605 
 
 c^-c 
 
 re"4 wH 2 s M H 
 N 0. 
 
 CH 3 
 
 CH 3 N 
 
 -co 
 
 CO CH -f 
 
 C ,CH 
 
 (I) 
 
 i 
 
 N=COC 2 H 5 
 H0 2 C 6 H 4 CH 2 SC CH NO^JgH^HgSC CH 
 
 N C.CH, N C.( 
 
 (VTIl) 
 
 H=COCH 2 CH= 
 
 NH - CO 
 I I 
 
 CO CH 
 
 HH 
 
 H - C.CH, 
 
 The second product of reaction with methyl iodide proved to be an 
 addition compound, which we have expressed by Formula II. Not only 
 is this interesting substance formed by direct alkylation of (I) with an 
 excess of methyl iodide, but the same combination results also by interac- 
 tion of the pyrimidine V with methyl iodide when digested in methyl 
 alcohol. Hydrolysis of this substance with hydrochloric acid led to the 
 formation of 1,4-dimethyluracil (VI), proving that the second methyl 
 group does not link itself to nitrogen. The choice between the two other 
 possible linkings, namely, addition to sulfur of the mercapto group or 
 oxygen in the 6-position of the ring was indicated by the behavior 
 on hydrolysis. By this treatment the mercapto group of the addition 
 compound was replaced and identified as ^-nitrobenzyl disulfide (IV). 
 This sulfide is formed by oxidation of nitrobenzyl mercaptan, a change 
 that is brought about by the influence of traces of iodine also formed as 
 a product of hydrolytic change. In other words, we obtained no evidence 
 of the formation by hydrolysis of the sulfide NC^CeH^CI^SCHs.* 
 
 ' The study of these addition compounds will receive attention in the immediate 
 future. (T. B. J.) 
 
2606 WILUAM J. HORN. 
 
 This is the first case to be described where we have been able to isolate 
 an addition product of this type, and the result indicates that such combi- 
 nations have probably resulted in previous condensations and that their 
 formation is a partial explanation of the low yields and abnormal results 
 obtained in many cases. Johnson and Jones 8 have shown that the pyri- 
 midine, 2-ethyl-mercapto-3-methyl-5-ethoxy-6-oxypyrimidine, combines 
 with potassium iodide to form a characteristic addition product. Our 
 addition product, II, was absolutely free from inorganic material. 
 
 The fact that iodine is formed by hydrolysis of the addition product 
 (II) in acid solution is strong evidence that the alkyl halide has dissociated 
 in the process of addition to the pyrimidine and this condition is expressed 
 by the structural formula assigned. The identification of this addition 
 product is strong evidence in support of the assumption that all these 
 alkylations in the pyrimidine series probably operate through the inter- 
 mediate formation of addition compounds. 
 
 Ethyl bromide and allyl bromide interact with the sodium salt of the 
 mercapto-pyrimidine in an entirely different manner from methyl iodide. 
 In neither case did we observe the formation of nitrogen-substituted 
 derivatives, but both halides interacted to form imido ester combinations. 
 The structures of these compounds are expressed by Formulas VIII and 
 IX respectively. The constitution of both of these pyrimidines was 
 established by the fact that they underwent hydrolysis with formation of 
 4-methyluracil and nitrobenzyl-mercaptan. 
 
 In the experimental part of this paper are recorded some new facts bear- 
 ing on the chemistry of p-nitrobenzyl-mercaptan and its corresponding 
 sulfide derivatives. 
 
 Experimental Part. 
 
 2-Thio-4-methyluracil and -Nitrobenzyl Chloride. The method employed for 
 the preparation of 2-thio-4-methyluracil was that used by Wheeler and McFarland; 7 
 -nitro-benzyl chloride was prepared according to the directions of Alway. 8 
 
 2-/?-Nitrobenzyl-mercapto-4-methyl-6-oxypyrimidine. (I). This pyrimidine was 
 obtained in quantity by the action of -nitrobenzyl chloride upon the sodium salt of 
 2-thio-4-methyl-uracil. 
 
 To sodium ethylate solution, prepared by dissolving a molecular proportion of 
 sodium in absolute alcohol, finely pulverized 2-thio-4-methyl-uracil was added. On 
 heating this mixture for two hours and shaking occasionally, the sodium salt separated 
 an4 the solution became reddish-yellow in color. -Nitrobenzyl chloride was then 
 added and the resulting solution was heated until it became neutral. The solution, 
 turned green at first and then dark red. After it had been heated for about 20 minutes 
 it solidified to a white cake. At the end of the reaction, the mixture was cooled, filtered 
 with the aid of suction and the crystalline product was treated with cold water to dis- 
 solve the sodium chloride formed in the reaction. The yield of crude pyrimidine was 
 
 Johnson and Jones, THIS JOURNAL, 31, 590 (1909). 
 
 7 Wheeler and McFarland, Ref. 2. 
 
 8 Alway, THIS JOURNAL, 24, 1060 (1902). 
 
OF MERCAPTO-PYRIMIDINES. 2607 
 
 93%. This compound is only slightly soluble in hot alcohol and difficultly soluble in 
 hot water. It was purified by recrystallization from glacial acetic acid, from which it 
 separated in the form of resets of colorless needles. These were collected on a filter, 
 washed, first with a little acetic acid and then with water, and dried at 115 for 10 to 
 15 hours. By this procedure, an 80% yield of the pure compound was obtained; it 
 melted at 220 to give a clear yellow oil. 
 
 Analyses. Calc. for C 12 HnO 3 N 3 S: N, 15.16; S, 11.55. Found: N, 15.24, 15.6; 
 S, 11.42. 
 
 Alkylation of 2-/>-Nitrobenzyl-mercapto-4-methyl-6-oxypyrimidine. 
 Action of Methyl Iodide. 
 
 To a sodium methylate solution, made by dissolving a molecular proportion of 
 sodium in methyl alcohol, finely pulverized 2-/>-nitrobenzyl-mercapto-4-methyl-6- 
 oxypyrimidine was added and the clear greenish-yellow solution thus obtained was 
 heated for one hour. By means of a dropping funnel, slightly more than the calculated 
 quantity of methyl iodide was then added slowly to the warm solution of the sodium 
 salt and the solution was heated until it became neutral. Upon removal of the alcohol 
 by evaporation under diminished pressure, a greenish-yellow solid separated which had 
 the odor of parsnips. This product was triturated with cold water to dissolve sodium 
 iodide, and the insoluble material collected on a filter was dried in a vacuum desiccator 
 over sulfuric acid for several days. This substance gave a very strong test for iodine 
 on treatment with sulfuric acid. When the finely pulverized product was extracted in a 
 Soxhlet apparatus with dry ether free from alcohol for 25 hours, it was separated into 
 two distinct compounds, one of which (^4) was soluble in ether, and the other (B) in- 
 soluble. 
 
 (A) l,4-Dhnethyl-2-^-nitrobenzyl-mercapto-6-oxypyriniidme. (V). On evapo- 
 rating the ether solution containing the soluble compound (A ] to dryness in the air, a 
 yellow solid was obtained which represented 71.5% of the weight of the total alkylated 
 products. This compound was free from iodine and melted between 90 and 111. Upon 
 recrystallization from glacial acetic acid, it was obtained in the form of resets of white 
 needles which melted sharply at 136 to give a clear yellow oil. It was identified as a 
 monomethyl derivative of the original pyrimidine. 
 
 Analyses. Calc. for Ci 3 H 13 O3N 3 S: N, 14.4. Found: 14.14, 14.16. 
 
 HYDROLYSIS WITH HYDROCHLORIC ACID. The structure of this compound 
 was established by its behavior on hydrolysis with cone, hydrochloric acid. One to 
 three g. of the compound was digested in 100 cc. of the acid for several hours. In about 
 10 minutes, the boiling solution became turbid and a yellowish-brown oil separated on the 
 surface of the liquid. At the end of the reaction period, the solution was filtered to re- 
 move the oil and the filtrate evaporated to dryness. By this procedure, a yellowish- white 
 residue was obtained which melted at 256-258 ; the yield was nearly quantitative for 1,4- 
 dimethyluracil. After recrystallization from hot water and treatment with Norite, 
 the substance was obtained in the form of colorless prismatic needles free from sulfur. 
 These crystals melted sharply at 259-260 to give a clear red oil. 
 
 Analyses. Calc. for C 6 H 8 O 2 N 2 : N,20.0. Found: 19.93,19.72. 
 
 The yellowish-brown oil insoluble in water solidified as it cooled to give a pearl-white 
 solid. Dried in a vacuum desiccator over sulfuric acid the substance was obtained in 
 quantity corresponding very closely to the quantitative yield for ^-nitrobenzyl-mercap- 
 tan . This compound is only very slightly soluble in water, but is very soluble in ether. It 
 was purified by recrystallization from alcohol from which it separated in the form of 
 white transparent plates melting sharply at 58 to a clear yellow oil. A molecular n 
 weight determination was made by the freezing-point method. 
 
2608 WILLIAM J. HORN. 
 
 Analyses. Calc. for C 7 H 7 O 2 NS: N, 8.28; S, 18.93; Mol. wt., 169.0. Found: N, 
 8.13, 8.47; S, 18.54; Mol. wt., 160.2, 164.8. 
 
 A further description of this compound is given below in the section devoted to 
 the chemistry of nitrobenzyl-mercaptan. 
 
 (B) The Addition Product of Methyl Iodide and l,4-Dimethyl-2-/>-nitrobenzyl- 
 mercapto-6-oxypyrimidine. (II). The insoluble amorphous compound (B) which was 
 yellowish-brown in color, was observed to turn red slowly on exposure to the air, a 
 behavior which was due evidently to the liberation of iodine. After drying this com- 
 pound in a vacuum desiccator over sulfuric acid for several days, the weight was found 
 to correspond to 28% of the weight of the total alkylated products. In a repetition 
 of the alkylation with methyl iodide with a quantity of the iodide greater than that 
 previously used, as high as 50% of the insoluble addition compound was obtained in 
 this reaction. This product did not melt sharply; the melting point ranged between 
 79 and 136. It gave a very strong test for iodine when treated with sulfuric acid and 
 left no residue when heated on platinum foil. When boiled in 50% alcohol, it was found 
 to dissociate, and the cool solution deposited white needle-like crystals. The com- 
 pound formed melted at 136 and was identified as l,4-dimethyl-2--nitrobenzyl-mer- 
 capto-6-oxypyrimidine. 
 
 The addition compound was purified by dissolving it to saturation in hot 80% 
 alcohol, filtering off any undissolved material and cooling the solution immediately 
 in an ice-bath, with stirring. By this procedure the compound was obtained in the 
 form of a light brown colloidal precipitate. It was collected and washed with a little 
 80% alcohol, and dried in a vacuum desiccator over sulfuric acid for several days. 
 Yield, 61%. It melted between 65-75 with slight decomposition. 
 
 Analyses. Calc. for Ci 4 H 18 O 3 N,SI: N, 9.69. Found: 9.50,9.39. 
 
 HYDROLYSIS WITH HYDROCHLORIC ACID. From 1 to 5 g. of the addition compound 
 was hydrolyzed by digestion with 50 cc. of cone, hydrochloric acid for several 
 hours. During this operation a yellowish-brown oil separated which solidified immedi- 
 ately when cooled. The yellow solution was then filtered and the residue dried and saved. 
 This compound was identified as -nitrobenzyl disulfide. The yield was nearly quan- 
 titative. Two recrystallizations from alcohol gave a product which separated in the 
 form of colorless needles melting at 126 to give a clear yellow oil. A molecular- weight 
 determination was made by the boiling-point method. 
 
 Analyses. Calc. for CnH^CUNzS*: N, 8.33; S, 19.05; Mol. wt., 336.0. Found: 
 N, 8.02, 8.34; S, 19.02, 19.09; Mol. wt., 334.5, 346.2. 
 
 A further description of this compound and its properties is given in the section 
 dealing with the chemistry of p-nitrobenzyl-mercaptan. 
 
 The yellow acid filtrate was extracted several times with ether. On evaporating 
 the solvent a crystalline solid was obtained which was identified as free iodine. 
 
 When the filtrate from the ether extractions was evaporated to dryness, a grayish- 
 black solid was obtained. The residue was treated with a little cold alcohol to remove 
 traces of iodine, and then recrystallized twice from hot water and decolorized by treat- 
 ment with Norite. As the solution cooled, the compound separated in the form of white 
 prismatic needles. The melting point, 259-260, indicated that we were dealing with 
 dimethyluracil. 
 
 When the pyrimidine, l,4-dimethyl-2--nitrobenzyl-mercapto-6-oxypyrimidine 
 (A) was hydrolyzed with cone, hydrochloric acid to which a little free iodine had been 
 added, the results were similar to those obtained by hydrolysis of the above addition 
 compound. That is, -nitrobenzyl disulfide and 1,4-dimethyluracil were formed 
 in this reaction. 
 
 Synthesis of the Addition Product from its Components. To synthesize the addition 
 
ALKYLATION OF MERCAPTO-TYRrMlW*nS.. ' 2609 
 
 compound, methyl iodide (3 moles) was added to a warm alcohol solution of 1,4-dimethyl- 
 2--nitrobenzyl-mercapto-6-oxypyrimidine and the solution was boiled for 12 hours. 
 As it cooled, yellow needle-like crystals separated. These were found to be free from 
 iodine and after recrystallization from glacial acetic acid, melted at 136 , which corre- 
 sponds to the melting point of the unaltered mercapto-pyrimidine. After the removal of 
 the methyl alcohol and methyl iodide from the nitrate by distillation, a light brown prod- 
 uct was obtained. This gave a very good test for iodine. Digestion with hydrochloric 
 acid transformed it smoothly into -nitrobenzyl disulfide, which melted at 135.5, 
 and 1,4-dimethyluracil, melting at 260. 
 
 Alkylation with Ethyl Bromide. 
 
 2-^-Nitrobenzyl-mercapto-4-methyl-6-ethoxy-pyrimidine. (VIII). 2--Nitroben- 
 zyl-mercapto-4-methyl-6-oxypyrimidine was added to a sodium ethylate solution made 
 by dissolving a molecular proportion of sodium in absolute alcohol, and the solution 
 was heated for 3 hours. A little more than the molecular quantity of ethyl bromide 
 was then added slowly through a dropping funnel and the solution was heated until it 
 became neutral. The hot solution was filtered to remove sodium bromide, and as the 
 filtrate cooled, resets of needle-like crystals separated. After filtering and treating 
 the residue with a little water to remove any traces of sodium bromide, the. above 
 pyrimidine was obtained; it melted between 90 and 96. Recrystallization from al- 
 cohol gave a product which melted sharply at 104. Yield, about 32%. 
 
 Analyses. Calc. for CuHuOgNsS: N, 13.77. Found: 13.70, 13.90. 
 
 HYDROLYSIS WITH HYDROCHLORIC ACID. From 1 to 3 g. of this compound 
 was hydrolyzed by digestion with 100 cc. of cone, hydrochloric acid for 3 hours. 
 The solution was filtered to remove the oil which separated and evaporated to dryness, 
 yielding a yellowish-white solid. This compound was identified as 4-methyluracil. It 
 was obtained in the form of white prismatic needles which crystallized from water and 
 did not melt below 300. The yield was quantitative. 
 
 Analyses. Calc. for C 5 H 6 O 2 N 2 : N, 22.22. Found: 22.24, 22.38. 
 
 When the oily product formed in this reaction was cooled, it solidified to form a 
 pearl-white solid which corresponded in quantity very closely to the calculated yield 
 for ^-nitrobenzyl-mercaptan. After recrystallization from alcohol, it was obtained 
 in the form of white transparent plates melting at 57 to give a clear yellow oil. A 
 mixture of this compound with -nitrobenzyl-mercaptan obtained in a previous ex- 
 periment melted at 57-58. 
 
 Alkylation with Allyl Bromide. 
 
 2-p-Nitrobenzyl-mercapto-4-methyl-6-alloxy-pyrimidine. (IX) . To sodium ethyl- 
 ate solution made by dissolving a molecular proportion of sodium in absolute alcohol, 
 2-/>-nitrobenzyl-mercapto-4-methyl-6-oxypyrimidine was added and the solution was 
 heated for 2^ hours. Allyl bromide (1 mol.) was then added slowly through a dropping 
 funnel and the resulting solution was heated until it became neutral. On removal of 
 the alcohol by distillation, a soft, sticky, dark red solid separated. This was dried in a 
 vacuum desiccator over sulfuric acid for several days, and then extracted in a Soxhlet 
 apparatus with dry ether free from alcohol. By this procedure two compounds were 
 obtained; a compound insoluble in ether, which proved on purification to be unaltered 
 material, and a compound soluble in ether. 
 
 When ether solution of the soluble compound was evaporated to dryness in the air, 
 a reddish-yellow residue was obtained. After two recrystallizations from ligroin the 
 compound was isolated in the form of light yellow needles which melted at 77-78 to 
 form a clear yellow oil. 
 
2610 ' WILUAM J. HORN. 
 
 Analyses. Calc. for C^HisOaNsS: N, 13.25. Found: 13.42, 13.52. 
 
 HYDROLYSIS WITH HYDROCHLORIC ACID. A small quantity of this compound 
 was hydrolyzed by digestion with 100 cc. of cone, hydrochloric acid for 1 */ hours. 
 The hot solution was filtered to remove the oil which separated and the filtrate was 
 evaporated to dryness. A nearly quantitative yield of 4-methyluracil was thus ob- 
 tained which, on recrystallization from water, did not melt below 300. 
 
 By recrystallization of the oily product from alcohol, white transparent plates 
 were obtained which melted at 57 to give a clear yellow oil. 
 
 The Chemistry of ^-Nitrobenzyl-mercaptan. 
 
 When we endeavored to identify ^-nitrobenzyl mercaptan (NO 2 C 6 H 4 - 
 CH 2 SH), formed in the hydrolysis of some of the 2-mercapto-pyrimidines, 
 unexpected results were obtained. We obtained a product which melted 
 consistently at 58, while the melting point assigned to this compound 
 in the literature is 140. This marked discrepancy led us, therefore, 
 to an investigation of the properties of this mercapto compound and its 
 corresponding sulfide derivatives. We found that our product melting 
 at 58 gave analytical results in complete agreement with those required 
 for the mercaptan. When this compound was subjected to oxidation 
 in the presence of iodine, or with potassium permanganate, or air in the 
 presence of ammonia, it was transformed into the disulfide (NO 2 C6H 4 CH 2 ) 2 S2 
 melting at 126.5. Price and Twiss 9 give the melting point of this 
 compound as 126.5. It was prepared by these chemists by the action 
 of sodium carbonate upon ^-nitrobenzyl thiosulfate. 
 
 Strakosch, 10 who investigated the preparation of -nitrobenzyl-mercap- 
 tan, prepared it by the action of potassium hydrosulfide and ammonium 
 sulfide upon ^-nitrobenzyl chloride and states that these reactions lead 
 to the formation of /?-nitrobenzyl-mercaptan melting at 140. He also 
 states that, in the case of the action of ammonium sulfide upon p-nitro- 
 benzyl chloride, prolonged boiling leads to the formation of p-mtro- 
 benzyl disulfide which he describes as melting at 89. On repeating his 
 work, with potassium hydrosulfide as a reagent, it was impossible to iso- 
 late any of the compounds which he describes. Furthermore, it was found 
 that ammonium sulfide reacts with ^-nitrobenzyl chloride in alcoholic 
 solution to give only the sulfide (NO 2 C 6 H4CH 2 )2S melting at 158-159. 
 
 WTien ^-nitrobenzyl chloride was treated with sodium hydrosulfide 
 in alcoholic solution, we obtained two compounds; the disulfide melting 
 at 126, and the sulfide melting at 158-159. This compound corre- 
 sponds to ^-nitrobenzyl sulfide described by O. Fischer. 11 
 
 The interesting results obtained with ^-nitrobenzyl-mercaptan raise the 
 question whether the corresponding ortho and meta isomers of this mercapto 
 compound have been correctly described. 
 9 Price and Twiss, J. Chem. Soc., 93, 1401 (1908). 
 10 Strakosch, Ber. t 5, 698 (1872). 
 " O. Fischer, ibid., 28, 1338 (1895). 
 
"***:*: :' * 
 
 YRiMiDixrvS. 2611 
 
 Summary. 
 
 1. Methyl iodide interacts with the sodium salt of 2--nitrobenzyl- 
 mercapto-4-methyl-6-oxypyrimidine to give first a nitrogen substituted 
 derivative, which then interacts with another molecule of methyl iodide 
 to form an addition product. The methyl group substitutes in the 1- 
 position of the pyrimidine ring. 
 
 2. Ethyl bromide and allyl bromide interact with the mercapto- 
 pyrimidine in a manner entirely different from that with methyl iodide. 
 In both of these cases, an oxygen ether is formed, and no evidence was ob- 
 tained of substitution of the alkyl groups on a nitrogen atom of the pyrim- 
 idine ring. 
 
 3. In the hydrolysis of 2-^-nitrobenzyl-mercapto-pyrimidines with 
 acids, ^-nitrobenzyl-mercaptan is formed melting at 57-58. If, however, 
 free iodine functions during hydrolysis, this mercaptan is destroyed and 
 the disulfide, melting at 126.5, is formed by oxidation. 
 
 4. The literature concerning ^-nitrobenzyl-mercaptan is incorrect; 
 in this paper the melting points of this compound, its disulfide and corre- 
 sponding monosulfide are described correctly. 
 
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