98 XI.--On certain ~~ze72yZthiocnrbamates. By H. LLOYD SNAPE, D.Sc., Ph.D. IN a paper (Trans., 1885,47, 778) published in this Journal some years ago, I described the action of phenylic cyanate on phenylic mercaptan, a phenylic salt of pheny lthiocarbamic acid, having the formula CGHS*S*C0*NHC6H5 being formed ; and I pointed out that an isomeride in which the oxygen and sulphur atoms had exchanged positions might be expected to be obtained by the action of phetiyl- thiocarbimide on phenol. That experiment, and also the action of the same thiocarbimide on phenols, I had proposed to investigate, but., unfortunately, it has been impossible for me to do this until recently. Meanwhile, the reaction with phenol itself has been inves- tigated by Professor A. E. Dixon (Trans., 1890, 57, 268) ; but, as this had escaped my attention until my experiments had been com- pleted, and I had obtained a purer product and a better yield, a few notes on my own examination of this reaction may be advantageously added. .Pheiaylthiocarbinaide and Phenol.These two substances were heated, in molecular proportion, in a sealed tube at temperatures varying from 100' to 280°, and for periods varying from 2 to 67 hours ; contrary to Dixon's experience, I found that the higher the temperature, provided it was not allowed to rise much above 270°, and the longer the time during which these substances were heated together, the better was the yield of the thio- carbamate ; the temperature should not be allowed to rise above 280°, as decomposition then sets in, and the product is a nearly black mass, from which it is difficult to separate the required crystals.I obtained the best yield after heating the mixture for nearly three days, the temperature for the greater part of the time varying from 250' to 280'. The product, a viscous, brown liquid, when allowed to stand in the cold, gradually deposited crystals, until, in from three to four days, the whole appeared to have become solid. The yield, under the above circumstances, after washing, pressing, and drying (as described by Dixon), amounted to nearly 25 per cent. of the theo- retical; Dixon, working at a lower temperature and heating for a shorter time, obtained only 7 per cent. These crystals were nearly pure, and were readily obtained in perfectly pure condit.ion by crys- tallisation from absolute alcohol, as well formed, highly lustrous, pale yellow leaves or needles, which melted sharply at 148' (Dixon found the melting point to be between 249' and 151').The substanceSNAPE ON CERTAIN PHENYLTHIOCARBAMATES. 99 could alao be crjstallised from glacial or dilated acetic acid, but was insoluble in ether and light petroleum. A determination of sulphur, by Carius' method, gave the following result. 0.126 yielded 0.129 BaS04. S = 14.03 (Dixon found 13.48). C,,HI1NSO requires S = 13.97 per cent. The other properties described by Dixon for the phenyl salt of 9-phenylthiocarbamic acid were confirmed. So much difficulty having been experienced i n effecting combina- tion between phenylthiocarbimide and phenol, it was to be anticipated that an action between the former substance and more complex phenols would not readily occur, and, actually, I found it impossible to effect a combination between the above-named thiocarbimide and either resorcinol or quinol.I also tried the effect of heating phenyl- thiocarbimide with glycol, but again without effecting direct corn- bination. The experiments are briefly summarised below. Yhenyt thiocarbimide and Resorciizot. These two substances were heated together in a sealed tube, in the proportion of twice the molecular weight of the former to once that of the latter; after two hours at 100" to 150°, no change was observable, and, even after heating for another hour a t 180°, the resorcinol crystallised out on cooling, and the thiocarbimide had acquired a slightly darker colour. On heating for a further period of 2+ hours at 175-18@", a beautiful, blood-red liquid was obtained, from which crystals of resorcinol separated on cooling; the red oil smelt strongly of the thiocarbimide, did not solidify on further cooling, was insoluble in water, readily dissolved in alcohol, glacial acetic acid, and benzene, but at once separated again as an oil on evaporating these solutions.The oil appeared to be the product of a partial decomposition of the thiocarbimide, and I could not find any trace of the formation of a thiocarbamate. Phenylthiocarbirnide and Quinot. Tho results obtained on examining the behaviour of this pair of substances, when heated together, were similar; up t o 180°, very little change was obseived.After heating for 15 hours at 200°, crystals of quinol separated unaltered, but the thiocarbimide bad again sustained some decomposition, the colour having diatinctly deepened, and at 220" a black mass was obtained, but no thiocarb- amate. I next endeavoured to effect a reaction between these two substances by hating them together first in benzene solution and then in glacial acetic acid solution. The decomposition of the thio-100 SNAPE ON CERTAIN PHENYLTHIOCARBAMATES. carbimide, as was to be anticipated, did not take place at as low a temperature as before, but again there was no indication of combina- tion occurring between the two substances. Phenylthiocarbimide and Glycol. On heating these two substances together for four hours at 265O, a few minute crystals separated, but I could not succeed in obtaining a sufficient quantity for examination, and longer heating only resulted in effecting decomposition, the entire liquid acquiring a deep, brownish-black colour.From this oil I failed to isolate any crystal- lisable substance ; it dissolved in alcohol, ether, glacial acetic acid, and benzene, but, on evaporating these solutions, only oily drops, consisting of the original materials employed, together with decom- position products, were obtained. Having thus failed to effect combination between phenylthiocarb- imide and dihydroxy-compounds, I next endeavoured to prepare the isomerides of the thiocarbamates I had hoped in this way to obtain, by the action of phenylic cyanate on the corresponding thiophenols, and I completely succeeded, both in the case of dithioresorcinol and of dithioquinol.These thiophenols J prepared by the method described by Koerner and Monselise (Cazzettn, 1876, 6, 133--1421, and found no difficulty in obtaining them in a state of purity, possessing the exact melting points given in the paper by the above-named chemists. I n the necessary previous preparation of the respective calcium salts of meta- and para-benzenedisulphonic acids, I noted, however, an error in IVatts’s Dictionayy (1, 458), which may possibly mislead others. It is there stated that, in separating these calcium salts by crystal- lisation, the meta-salt separates $&, whereas the reverse is the case. I was unable to refer to the original papers, and, though i t seemed unlikely that only the calcium salt of the meta-acid should be less soluble than that of the para-acid, I was only able to determine this with certainty by the later preparation of the sulphonic chlorides.Metaphenylene PTLeiz2/lthiocarbama.te. Phenylic cyanate and dithioresorcinol, in the theoretical propor- tions, were heated in a sealed tube by meam of a water bath contain- i n g a solution of common salt; after about half an hour, crystals commenced to separate, and, a few minutes later, the whole solidified to a crystalline mass. This was washed with cold absolute alcohol, to remove any excess of phenylic cyanate, the crystals themselves being almost insoluble in this solvent; they were also insoluble in water, but were dissolved by ether and also by gkicial acetic acid, and could readily be recrystallised from these liquids. From glacialSNAPE ON CERTAIN PHENTLTHIOCARBAMATES.101 acetic acid, the thiocarbamate separated in the largest crystals, these consisting of white needles, as much as 1 cm. in length, wbich gradually grew in the solution in beautiful tufts. They melted at 178-159", and beiow that temperature were stable; at a higher temperature, however, the substance decomposed with energetic evolution of hydrogen sulphide and other gases possessing an un- pleasant odour ; but the sulphur was not removed by merely heating some of the crystals in a test-tube with an alkaline solution of lead hydroxide. On heating the crystals with fuming nitric acid, a very fine, wine-red solution was obtained. An estimation of sulphur, by Carius' method, gave the Eollowing result.0.112 gave 0.138 BaS04. The reaction which had occurred is therefore represented by the S = 16.92. C2,H,6Nz0,S2 requires s = 16.84 per cent. eqnat ion C,HeC,(SH), + 2CsH,*NCO = C6H4(SoCO*NH*C6HS)2. Paraphen ylene Phsn ylthiocarbanzat e. Phenylic cyanate and dithioquinol likewise readily enter into com- bination, even at the temperature of a water bath. It is not even necessary that they should be heated in a sealed tube, but it is better to do so, if only to protect the phenylic cyanate from the air, and thus to prevent the formation of carbanilide. The crystals formed were at first pale yellow, but, after repeated recrystallisation from boiling acetic acid, they were obtained as small, pure white needles ; the individual form of these was scarcely observable by the naked eye, but they tended to group themselves in tree-like aggregates. They were soluble also in ether, but in neither Rolvent was this substance so soluble as the meta-isomeride, nor did it yield large crystals so readily ; i t mas insoluble in water, and scarcely soluble in cold alcohol, but dissolved in boiling aniline. The crystals melted at 200--202°. The behavionr of the substance when heated to a higher temperature, and also on heating with nitric acid and with an alkaline solution OE lead hydroxide, respectively, was similar to that of the meta-compound. A determination of d p h n r , by Carius' method, gave the following r e d t . 0.1 gave 0.123 BaS04. which closely corresponds to the percentage (see preceding) theo- retically required. S == 16-89 per cent., University Cottege qf Wales, Aberystwyth.