ELECTROCHEMICAL FLUORINATION OF AROMATIC-COMPOUNDS IN LIQUID R4NF.MHF.1. BASIC PROPERTIES OF R4NF.MHF AND THE FLUORINATION OF BENZENE, FLUOROBENZENE AND 1,4-DIFLUOROBENZENE

A series of new electrolytes, R4NF . mHF (R: CH3, C2H5 and n-C3H7, m > 3.5), has been utilized for electrochemical fluorination of organic c ompounds. These electrolytes are non-viscous liquids at room temperatu re, and have high electrolytic conductivity and high electrochemical s tability. The electrolysis gave high current densities and high curren t efficiencies for the fluorination without any film formation at the anode. Benzene, fluorobenzene and 1,4-difluorobenzene were electrochem ically fluorinated on a platinum anode at 2.5 V (vs. Ag/Ag+ (0.01 mol dm-3)) in (C2H5)4NF.mHF. Electrochemically stable 3,3,6-trifluoro-1,4- cyclohexadiene(I) and 3,3,6,6-tetrafluoro-1,4-cyclohexadiene(II) were obtained as the final products for the fluorination of benzene and flu orobenzene. The electrolysis of 1,4-difluorobenzene gave II in ca. 90% yield. The current efficiency for the fluorination was sufficiently h igh; benzene, fluorobenzene and 1,4-difluorobenzene were fluorinated i n 66-70%, 71-76% and 88-90% current efficiences, respectively.