ANHYDRIDES OF ORGANIC ACIDS 237 



the two compounds, though general, are similarities in 

 behaviour common to acid chlorides, but if one takes into 

 account the far-reaching analogy between oxygen and sulphur 

 compounds, they may be held as pointing to similarity in 

 constitution. 



The amides corresponding to thionyl chloride and sulphur 

 chloride are unknown, but Michaelis has prepared the tetra- 

 alkylated derivatives of these compounds by the action of 

 thionyl chloride (Ber., 1895, 28, 1016) and of sulphur chloride 

 (loc. cit. 9 165) respectively on dialkylamines in presence of 

 ether, the reactions in each case being quite parallel : 



SOC1 2 +4NH(C 2 H 6 ) 2 = SO[N(C 2 H 5 ) 2 ] 2 +2NH(C 2 H 5 ) 2 .Ha. 

 S 2 C1 2 +4NH(C 2 H 5 ) 2 = S 2 [N(C 2 H 6 ) 2 ] 2 +2NH(C 2 H 5 ) 2 .HC1. 



The existence of amides and acyl derivatives of thio- 

 sulphurous acid makes it appear probable that corresponding 

 esters might also be obtained, and such compounds have been 

 described by Lengfeld (Ber., 28, 449), who investigated the 

 reactions which take place between sulphur chloride and the 

 methoxide and ethoxide of sodium respectively in presence 

 of light petroleum. The writer has not, however, succeeded 

 in preparing these compounds either by Lengfeld's method 

 or by modifications of it. 



What appears to be direct evidence in favour of the 

 sulphothionyl constitution of sulphur chloride is afforded by 

 its formation from thionyl chloride by the action of phos- 

 phorus pentasulphide : 



P 2 S 5 +5 : SC1 2 = P 2 6 +5 S : SC1 2 (Carius, toe. tit.) 



but according to Prinz (Annalen, 223, 355) the change does 

 not occur directly. 



The converse transformation, that of sulphur chloride 

 into thionyl chloride, can be effected by the action of sulphur 

 trioxide at a temperature of 75-80. 



S0 3 + S 2 C1 2 = SOCl 2 +SO a +S. 



