38 Proceedings of the Boyal Irish Academy. 



sulphur chloride on aniline in chloroform solution at 50°, and obtained thio- 

 aniline. More recently, Coffey' has made a fuller study of this case, and 

 showed that at low temperatures the reaction takes place quantitatively, 

 according to the equation — 



3C.H5NH, + S.CU = CeHjNSo + 2C6H5NH,, HCl. 



The work described in this paper was undertaken before Coffey's publica- 

 tion appeared, and we are able to confirm his results, as a similar reaction 

 takes place with 9;i-toluidine, which we selected as a typical case. To isolate 

 the products of the reaction 19'3 grams (3 mols.) of the base were dissolved 

 in 150 c.e. of anhydrous ether, and the solution cooled in a freezing mixture 

 to below - 15°. 8'1 grams (1 mol.) of sulphi^r monochloride dissolved in 

 30 c.c. of dry ether were slowly added from a dropping funnel, the mixture 

 being mechanically stirred during the reaction. The solution becomes 

 coloured, and toluidine hydrochloride separates out. Additional ether is 

 added to the mixture after half of the sulphur chloride has been introduced 

 as the separated hydrochloride makes stirring somewhat difficult. After all 

 the sulphirr chloride has been added, the mixture is kept in the freezing 

 mixture and stirred for an hour. It is then filtered, and the hydrochloride 

 washed with ether. The solvent is removed from the combined filtrates in 

 an evacuated desiccator, and a reddish-brown solid soon begins to separate. 

 The first fractions of this are rejected, and the part which separates out sub- 

 sequently is kept in a vacuum desiccator for a further forty-eight hours to 

 remove all traces of ether, and is then analysed. It is pure N-dithiotoluidine. 

 (Found jST = 8-1 per cent. : C7H7NS2 requires N = 8-3 per cent.) 



The substance appears to polymerise on keeping, especially if exposed to 

 air. It becomes oily, and the solubility in ether decreases. 



Hydrogen chloride gas decomposes a solution of dithiotoluidine in dry 

 ether, sulphur chloride and the base being formed. The reaction, therefore, 

 is reversible — 



ENH, + S^CL ^ ENS, + 2HC1. 



Aqueous hydrochloric acid also decomposes it, a mauve-coloured dye- 

 stuff and black tarry products being formed. The nature of these was not 

 further examined. 



Colours were also obtained by the action of sulphur chloride on other 

 aromatic compounds containing the NH, group, and it is hoped to determine 

 the course of the reaction in these cases later. Some of the results obtained 

 are shown in the table opposite. 



Rec. Trav. Chim., 1921, (4) 50, 745. 



