Pentoxydichloride Pyrosulfuryl Chloride

Disulfur pentoxydichloride is readily prepared by chlorinating sulfur trioxide with carbon tetrachloride. Since 

Disulfur pentoxydichloride has also been prepared by treating sulfur monochloride with sulfur trioxide vapor at low temperatures.  

During the addition of sulfur trioxide to the carbon tetrachloride no appreciable rise in temperature is observed and very little, if any, evolution of phosgene occurs. When 

Disulfur pentoxydichloride may be analyzed by adding a weighed amount (0.5 to 1 g.) to 150 ml. of ice-cold water and allowing the mixture to stand until the disulfiu pentoxydichloride, which at first forms an oily heavy drop, has disappeared by solution and hydrolysis in accordance with the equation  

An aliquot volume is then titrated with standard alkali and another portion is analyzed for chlorine by any one of the usual argentometric procedures. From the data, the purity 

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