1870.] 



Acids of the Sulphur Series. 



507 



gagement of gas. If it be formed at all, which I certainly do not hold to 

 be the case, it is immediately decomposed again in contact with the anhy- 

 dride into carbonic oxide and sulphuric clorhydrate. 



Action of Sulphuric Anhydride on Hexachlorbenzol. 

 This experiment was instituted in the hope of obtaining tetrachlorquinon, 

 which, as is known, Graebe * succeeded in converting into hexachlorbenzol 

 by the action of phosphoric chloride. The first step in the reaction would 

 be the formation of the body C 6 C1 4 0, which probably, by the intervention 

 of another molecule of the anhydride, would then be converted into 

 .0 



C G Cl 4 <^y I say probably, because there seems no tendency in the benzol 



series to form derivatives in which two of the monovalentic hydrogen atoms 

 are replaced by a single divalentic atom. 



However, no action whatever took place on heating the hexachlorbenzol 

 in sealed tubes with sulphuric anhydride alone, or with addition of pyro- 

 sulphuric chloride as dissolvent, to a temperature over 200° C. The tubes 

 burst frequently, but in all cases it was possible to separate out the hexa- 

 chlorbenzol perfectly unaltered on addition of water. Possibly better re- 

 sults might be obtained with tri- or tetrachlorbenzol in which is still 

 replaceable hydrogen. 



Experiments were also made with chlorobenzol, benzotrichlorid, and 

 dichlorhydrin, from the first two of which respectively benzoic aldehyde and 

 chlorbenzol might have been formed, — a view which was favoured by Op- 

 penheim's \ having obtained benzoic aldehyde by the action of concentrated 

 sulphuric acid on chlorobenzol and after-treatment with water. 



Dichlorhydrin was perfectly carbonized by the action of the anhydride, 

 HC1 and S0 2 being evolved, and the other two chlorides were converted, 

 also with evolution of HC1, into that peculiar resin-like substance which is 

 a so characteristic product in many reactions with these bodies. 



There seems, therefore, to be no doubt, as was indeed probable, that the 

 substitution of Cl 0 by O can only be effected in such compounds as are ca- 

 pable of resisting the action of the pyrosulphuric chloride formed thereby, 

 and that consequently it is only attainable in its purity in those cases where 

 the whole or greater part of the hydrogen is replaced by chlorine. 



Action of Sulphuric Anhydride on Ver chlorinated Chloride of Ethylene. 



On bringing these two bodies together and slightly warming, the reaction 

 soon set in, the latter melting ; a disengagement of gas also took place, an 

 examination of which proved it to be a mixture of carbonic oxychloride and 

 sulphurous anhydride. On continuing the application of heat, the contents 

 of the flask gradually became liquefied, and on subjecting afterwards to 

 distillation, the liquid commenced to boil at about 60° C. ; the thermometer 



* Ann. Ch. Pharm. cxlyi. p. 12. 



f Berichte d. Deutschen. Cheni. Ges. ii. p. 213. 



