Xenon difluoride reacts with 1, l-diphenylethylenes in the presence of hydrogen fluoride or trifluoroacetic acid as catalyst to form the corresponding 1, 2-difluoro-l, l-diphenylethanes in nearly quantitative yields. Reaction with l, l-diphenyl-2-fluoroethene in the presence of trifluoroacetic acid results in 1, 2, 2-trifluoro-l, 1-diphenylethane and 2, 2-difluoro-l, l-diphenyl- l-trifluoroacetoxyethane. Reaction with styrenes gives vicinal difluorides in lower yield.
