acid the yellow, crystalline picrate, and otherwise answered to the description of Gadamer's compound. The yield of recrystallised material was about 76 per cent. of the theoretical.

Some of the pure substance was dissolved in water, and the strongly acid solution mixed with excess of dilute caustic potash. A clear, almost colourless oil was at once deposited, but soon hardened; it was removed, well washed with water, and dissolved in hot, slightly diluted alcohol, from which, however, it separated as an oil, which did not solidify even when kept many days in a desiccator or under diminished pressure. The oil was nearly insoluble in water, slightly alkaline to test paper, had, especially when warm, a faint, rather unpleasant, basic odour, and was freely soluble in alcohol or acids. It contained bromine and sulphur, though withholding the latter from both alkaline lead and ammoniacal silver salts even on boiling. On examining the alkaline solution from which the organic base had been precipitated,* it was found to contain, in addition to a little base (which gradually separated from it on standing) much potassium bromide.

The oil was analysed for sulphur, with the following results. 0.1932 gave 0.2145 BaSO、. S = 15·26.

C,H,BrN2S requires S = 15·33,

Consequently the aqueous "dibromide" under the influence of dilute alkali loses half its bromine as hydrogen bromide, leaving a basic residue, C,H,N2SBr, the latter being presumably u-methyl-y-bromopenthiazoline, and the former its hydrobromide, which had been produced in the manner represented by the equation

CS

NH.CH,
+NHÁCH,CHỊCH,

+ 2Br= CHBr

CH2S
CHN

C-NH CH,,HBr.

The "chlorobromide" obtained from the "dibromide" by acting on it with silver chloride, was doubtless the hydrochloride of the brominated base, that is, C,H,N2SBг,HCl. In order to obtain it, the base was treated with hydrochloric acid, in which it readily dissolved, and the solution concentrated on the water bath; the clear brown acid syrup which was left became tough on standing, but did not crystallise.

The methyl derivative, like several of the penthiazolines already mentioned, gave, on treatment of the alcoholic solution with (neutral or ammoniacal) silver nitrate, an insoluble silver compound, very sensitive even to dim daylight; the yellowish-white precipitate retains its colour if kept in the dark, but rapidly changes on exposure to actinic light, through mauve and reddish, to deep purple.

11.5 grams of "dibromide" afforded 7 grams of brominated base, equal to 84 3 per cent. of the theoretical.

It remained to examine the action of dibromopropylthiocarbimide on methylamine.

The above constituents, in molecular proportion, were dissolved separately in alcohol, and the solution mixed, when, after a few seconds, a very vigorous action commenced, a portion of the contents being projected out of the vessel; on concentrating the residue and allowing it to stand, solid matter separated; this, when purified by recrystallisation and washing with alcohol, had the appearance and exhibited all the properties of the compound obtained by Gadamer from bromine and methylallylthiocarbamide, save that its melting point was not quite sharp (144–146°).

Secondary bases, as I have shown (loc. cit.), for instance, methylaniline and piperidine, also unite with dibromopropylthiocarbimide, affording disubstituted penthiazolines

CH,BrCHBr CH, NCS + NHMePh =

hence it may be safely concluded that Gadamer's dimethylallylthiocarbamide dibromide, and the chlorobromide which it gives with silver chloride, are the hydrobromide and hydrochloride respectively of the brominated base, u-dimethyl-y-brompenthiazoline,

Mention is made in the abstract above referred to of a trimethylallylthiocarbamide (from allylthiocarbimide and trimethylamine, at 150-160°) and its dibromide. If the former be really a thiocarbamide, its synthesis has a special interest, as being the only one of its kind hitherto effected. Allylthiocarbimide and triethylphosphine unite (Hofmann, Ann., Suppl., 1, 47) to form a compound, C10H0NPS = (?) (C2H2)2P·CS•N(C2H2) (C2H); but the only nitrogenous bases which have so far been combined with the thiocarbimides are those in which at least one typical hydrogen atom of the parent NH, is still retained.

Chemical Department,

Queen's College, Cork.

20

855

LVII.-Acidic Thiocarbimides, Thioureas, and Ureas. By AUGUSTUS E. DIXON, M.D.

IN communications recently made to this Society (Dixon and Doran, Trans., 1895, 565; Dixon, ibid., 1040), evidence has been adduced to show that the interaction between lead thiocyanate and the acid chlorides of the forms R'CO.Cl and R"(CO·CI), constitutes a general method for the production of thiocarbimides of the acidic class. Thus, by heating valeryl and cinnamoyl chlorides, in dry benzene, with lead thiocyanate, the compounds C,H, CO NCS and

CHCH:CH CO NCS

were obtained in solution; and similarly from succinyl and phthalyl chlorides, the dithiocarbimides, C2H,(CO·NCS), and C,H,(CO-NCS)2, respectively.

Excepting that they are all more or less readily decomposed in presence of water

R.CO.NCS+ H2O = R·CO·OH + HSCN,*

and cannot, consequently, be purified by steam distillation, the acidic thiocarbimides, so far obtained, resemble, in general, their congeners of the non-acidic class. They are extremely reactive, have a pungent and rather characteristic odour, and combine readily with alcohols, with phenylhydrazine, with ammonia,† and with (primary or secondary) amines, yielding the corresponding thiocarbamates, semithiocarbazides, and thioureas.

In connection with the last-named class of interaction, it may be noted that, whereas between non-acidic thiocarbimide and primary amine, the radicles may be exchanged without affecting the resultthus, for instance, ab-ethylphenylthiocarbamide occurs indifferently from the union of either ethylthiocarbimide with phenylamine, or of phenylthiocarbimide with ethylamine-on the other hand, in the case of acidic thiocarbimides, the radicles are not thus interchangeable. Acetylthiocarbimide readily unites (Miquel, loc. cit., 318) with phenylamine, affording ab-acetylphenylthiocarbamide—

MeCO•NCS + PhNH, = MeCO NHCS NHPh,

but the converse process

PhNCS + MeCONH, = PhNH CSNH COMe,

so far at least as my experiments have gone, cannot be directly realised.

* Sometimes carbonyl sulphide is formed; for instance, PhCO·NCS + H2O = PhCO NH2+COS (Miquel, Ann. Chim. Phys. [5], 11, 300).

Not always, however, so as to afford a thiourea as the end-product.

=

The work referred to in the papers above mentioned, and in other previous communications, originated in an examination of Miquel's "acetyl thiocyanate" (loc. cit.); this substance, however, in relation to bases, behaves generally as a thiocarbimide, and unless it, and its allies, be tautomeric, the true acidylthiocyanates apparently yet remain to be discovered. In the present communication, an account is given of an extension of the method in question to the preparation of certain thiocarbimides derived from acids which belong, either by structure or function, to the aliphatic class.

I. PROPIONYLTHIOCARBIMIDE, C2H, CO·NCS, AND ITS DERIVATIVES. Propionyl chloride, when added to excess of dry, very finely divided lead thiocyanate, acted vigorously, without the application of heat, and by distilling off on the oil bath heated to about 180°, a clear, highly refracting liquid came over of pungent and tear-exciting odour, colourless at first, but becoming brownish on keeping. This liquid was miscible in all proportions with alcohol and ether but insoluble in cold water, slowly decomposing in contact with it, or more rapidly on heating, with formation of thiocyanic acid. Its alcoholic solution, when mixed with ammoniacal silver nitrate or alkaline lead tartrate, was copiously desulphurised on warming, thus indicating the presence of a thiocarbimide. Analysis was considered unnecessary, in view of the well-marked derivatives which it afforded when treated in solution with nitrogenous bases. The yield by the above method was very unsatisfactory, but by operating as described in former papers, namely, heating the constituents together in anhydrous benzene until the solution was free from chlorine, filtering, and further diluting the filtrate to a known strength (1 gram-molecule per litre, assuming quantitative interaction), a clear, pale yellowish, pungently smelling liquid was obtained, which subsequent experiment showed to contain at least 90 per cent. of the theoretical amount of propionylthiocarbimide.

This solution, when shaken up with cold water, gave a faint thiocyanic reaction, but, if boiled for a few seconds with it, afforded an intense blood-red coloration on the addition of ferric chloride. In the experiments next described, the benzene solution, prepared as above, was employed.

ab-Propionylphenylthiocarbamide, C2H, CO NH-CS NH·C,H,.

Heat was evolved on mixing the thiocarbimide with aniline, both in benzene solution, and on concentration at the ordinary temperature, In one preparation, mercuric thiccyanate was used; it did not appear to possess any advantage over the lead salt.

and vitreous crystals separated; after being drained by aid of the pump, washed with spirit, and air-dried, the yield amounted to only about 66 per cent. of that obtainable according to the equation

C,H,CO NCS + CHNH, = C,H,CO NH•CS NH•CH, and reckoned on the amount of chloride used. By repeated recrystallisation from boiling spirit, brilliant, long, colourless prisms were obtained, melting constantly at 129-130° (corr.), without decomposition.

A sulphur determination served to establish the identity of the compound.

0.2018 gave 0.2295 BaSO4. S = 15.63.

C10H12N2SO requires S = 15·40 per cent.

Propionylphenylthiocarbamide is very sparingly soluble in boiling water, crystallising from it in slender needles, almost insoluble in the cold; moderately soluble in hot alcohol, ether, and carbon bisulphide, easily in hot benzene, very freely in chloroform. It also dissolves readily in dilute caustic alkali; the latter solution, when mixed with alkaline lead tartrate, is desulphurised freely by warming. Silver nitrate, if added to a cold, dilute alcoholic solution, affords a yellowish precipitate, rapidly changing, through orange and brown, to black; with the ammoniacal nitrate, silver sulphide is instantly formed.

Action of Caustic Alkali.—Cold, dilute caustic potash dissolves the thiocarbamide with decomposition; if dilute hydrochloric acid be now added to the clear solution, a white solid at once separates, which, after recrystallisation from dilute alcohol, forms white prisms, sparingly soluble in cold, moderately in hot, water, having an intensely bitter taste, melting at 153-154°, and consisting of phenylthiourea.

EtCO NH•CS•NHPh + KOH = Et·COOK + CSN,H,Ph. This decomposition (under the influence of cold, dilute caustic alkali) of symmetrical disubstituted thiocarbamides containing an acid radicle, into a salt of that acid and the corresponding monosu bstituted thiourea, appears to be generic.

Action of Silver Nitrate.-By desulphurising a moderately concentrated, hot alcoholic solution of the thiocarbamide with a trifle over the calculated quantity of silver nitrate, filtering off the silver sulphide, and allowing the filtrate to evaporate slowly, a brownish solid was obtained, which, after several recrystallisations from spirit, yielded almost colourless, pearly flattened needles, melting, without decomposition, at 138-139° (corr.), and consisting, as shown by the result of a nitrogen determination, of the expected propionylphenylarea, C.HgCO NH·CO-NH-CH.