Polyfluoroarenes. Part XX. Some homolytic arylations with pentafluorophenylhydrazine

Abstract

Oxidation of pentafluorophenylhydrazine in benzene by aqueous reagents (CuSO₄, NaOCl, H₂O₂, and H₂O₂–FeSO₄) gives 2,3,4,5,6-pentafluorobiphenyl. Use of solid potassium permanganate in pyridine or silver oxide in a solution of naphthalene in carbon tetrachloride gives low yields of the corresponding pentafluorophenylarenes, but a 57% yield of 2,3,4,5,6-pentafluoro(phenoxy)biphenyls is obtained from the hydrazine and silver oxide in molten diphenyl ether. The isomer ratio for the last reaction has been determined. Unambiguous syntheses of the two pentafluorophenylnaphthalenes and the three 2,3,4,5,6-pentafluoro(phenoxy)biphenyls are described.