GB1232285A - - Google Patents

Abstract

1,232,285. Fluorinated benzene derivatives. W. CANNING & CO. Ltd. 15 Sept., 1969 [14 June, 1968], No. 28330/68. Heading C2C. [Also in Division C7] Fluorinated benzenes and substituted fluorinated benzenes are prepared by electrolytic reduction of a carbocyclic compound with a 6- membered ring having one or two double bonds, and substituted on the ring C atoms by 0 to 3 groups in the class: -R, -NR 2 , -OR, =NR, =O and -R F (R being the same or different and H or C 1-6 alkyl; R F being a fluorinated C 1-6 alkyl), and on the remaining ring atoms by F. A fluorinated cyclohexadiene, which may be substituted with H, C 1-6 alkyl or alkoxy, is electrolytically reduced to remove 2 F from the ring; e.g. hexafluorobenzene may be prepared from octafluorocyclohexadiene, tetrafluorobenzene from hexafluorocyclohexadiene and pentafluorotoluene from methylheptafluorocyclohexadiene. A fluorinated 1- amino-cyclohex-1-ene substituted on the 3- position by = O or =NR is electrolytically reduced to remove 3 or 4 F from the ring; e.g. tetrafluorophenylene diamine may be prepared from amino-imino-heptafluorocyclohexene, trifluorodimethylphenylene diamine from methylamino - methyliminoheptafluorocyclohexene, tetrafluoroisopropylaminophenol from isopropylaminoheptafluorocyclohexen-3-one and pentafluorophenetole fromethoxy-heptafluorocyclohexadiene. The fluorinated cyclohexadienes may be prepred by treating fluorocyclohexanes with KOH solution; and the fluorinated aminoimino-polyfluorocyclohexenes by treating a perfluorocyclic olefin with ammonia or amine. The starting cyclohexadiene may be dissolved in a catholyte solvent of water and an alkanol (e.g. methanol, ethanol or propanol), ether (e.g. dioxan) or a ketone (e.g. acetone) containing K or Na acetate as buffering agent. A porous barrier, e.g. a sintered glass disc, preferably prevents the catholyte and anolyte from mixing. The anolyte may also contain the buffering agent. The pH is preferably adjusted above 7 by adding acetic acid. The cathode may be a Hg pool, and the anode a Pt foil.