C. Depecker et al., Trifluoromethylation of aromatic compounds via Kolbe electrolysis in pure organic solvent. Study on laboratory and pilot scale, NEW J CHEM, 23(7), 1999, pp. 739-742
The present study investigates the conditions of trifluoromethylation of va
rious aromatic compounds via the Kolbe oxidation of trifluoroacetic acid. T
he preparative electrolyse conditions were first optimized on the laborator
y scale using the trifluoromethylation of benzonitrile in acetonitrile solu
tions as a model case. Sodium or pyridinium trifluoroacetates were tried as
a source of trifluoromethyl radicals, the partial neutralization of triflu
oroacetic acid by pyridine provided the best yield of trifluoromethylbenzon
itrile (46%). The trifluoromethylation of the other aromatic compounds such
as acetophenone, benzaldehyde and nitrobenzene led to yields slightly lowe
r than those observed in the case of benzonitrile. The trifluoromethylation
of benzonitrile was then studied in a commercially available how cell. Yie
lds were consistent with those obtained on the laboratory scale.