Hydrochloric Acid → 2,2-Bis-(4-mesyloxy-3-nitrophenyl)-hexafluoropropane

11.5 g (0.1 mol) of methanesulfonyl chloride are added dropwise, at a reaction temperature of 0-5° C., to a mixture of 21.3 g (0.05 mol) of 2,2-bis-(4-hydroxy-3-nitrophenyl)-hexafluoropropane and 100 ml of pyridine. Stirring is continued for 1 hour at 5° C. and overnight at room temperature. The reaction mixture is then acidified, first with dilute hydrochloric and then with half-concentrated hydrochloric acid; the precipitate which is deposited is filtered off with suction and washed with water until neutral. The crude product (29.3 g) is then recrystallized from toluene, resulting in 24.8 g of analytically pure 2,2-bis-(4-mesyloxy-3-nitrophenyl)-hexafluoropropane to be isolated. Yield 85%; m.p. 119-121° C.