236 THE PREPARATION OF 



For example, its decomposition by means of water to give 

 hydrochloric acid, sulphur dioxide, and free sulphur : 



S 2 C1 2 +2HOH = S 2 (OH) 2 +2HC1 

 2S 2 (OH) 2 = (2S 2 0+2H 2 0) = 3S+So 2 +2H 2 0. 



The general resemblance between sulphur and oxygen 

 compounds led Carius (Annalen, 1858, 106, 291) to regard 

 sulphur chloride as being sulpho-thionyl chloride, so that its 

 formula should be 



CxCl 

 corresponding to O : S< and not a . S . S . a. 

 \C1 



He looked upon the reaction between sodium benzoate and 

 sulphur chloride, in which benzoyl chloride is formed, as 

 taking place in two stages, in the first of which benzoyl 

 sulphide and thionyl chloride are produced : 



2C 6 H 5 . COONa+2S 2 Cl 2 = (C 6 H 8 CO) 2 S+2SOCl 2 +Na 2 S 



= 2C 6 H 5 . CO . Cl+2NaCl+S0 2 +3S J 



while he formulated the reaction between sulphur chloride 

 and water similarly : 



2H 2 0+S 2 C1 2 = H 2 S+2HC1+S0 2 

 2H 2 S+S0 2 = 2H 2 0+3S. 



It is thus evident that Carius, having in mind the possible 

 analogy between thionyl chloride and sulphur chloride, 

 looked upon reactions in which the latter substance and 

 oxygen-containing compounds take part as consisting in the 

 primary formation of thionyl chloride, which then may react 

 further. 



As already shown, however, it is possible to view these 

 reactions more simply, and to express, perhaps more clearly, 

 the analogy between the two chlorides, although at the same 

 time it should be noted that the analysis of the mechanism 

 of these reactions previously detailed holds good for either 

 constitutional formula. The similarity in the reaction of 



