Polyfluoroarenes. Part XIX. Pentafluorophenylation of biphenyl and 2,3,4,5,6-pentafluorobiphenyl

Abstract

Pentafluorophenylation of 2,3,4,5,6-pentafluorobiphenyl with radicals from the oxidation of pentafluorophenylhydrazine gives only low yields of terphenyls, but excellent yields of 2,2″,3,3″,4,4″,5,5″,6,6″-decafluoro-o-, m-, and p-terphenyl are obtained by photochemical pentafluorophenylation with radicals from pentafluoroiodobenzene. The photochemical reaction of pentafluoroiodobenzene with biphenyl itself also gives high yields of terphenyls. Unambiguous syntheses of the three 2,2″,3,3″,4,4″,5,5″,6,6″-decafluoroterphenyls and the three 2,3,4,5,6-pentafluoroterphenyls are described.