Benzophenone-3,3 -disulfonyl chloride

Chloro-7-inethoxynaphthalene-1-sulfonyl chloride Benzophenone-3.3 -disulfonyl chloride... 

However, Cremlyn and co-workers,discovered that benzophenone 220, by heating with excess of the reagent (six equivalents) at 140 °C (3 hours), afforded a low yield (15%) of the 3,3 -disulfonyl chloride 222 and the 3,3 -disulfonic acid (221, 60%) (Equation 70). Later workers claimed that using a larger excess of chlorosulfonic acid (10 equivalents) at 150 °C resulted in an improved yield (50%) of the disulfonyl chloride 222 repetition of the experiment largely confirmed their results, but gave a slightly lower yield of the product (40%). ... 

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