Examples of Commercialized Organic Electrode Processes - Fundamentals and Applications of Organic Electrochemistry - page 337

A.1 Electrochemical Fluorination
Anodic fluorination and anodic methoxylation
of ethyl phenylthioacetate [1,2]
Anodic partial fluorination of organic
compounds usually uses a poly(hydrogen
fluoride) complex of amine or ammonium salt
as the fluorine source and supporting
electrolyte. In an undivided cell, hydrogen
evolution by cathodic reduction of proton takes
place as well as the desired anodic fluorination
of a substrate. In an acetonitrile solution,
fluorination proceeds via an anodically
generated cation intermediate, whereas
methoxylation occurs selectively in a methanol
solution ( Eq. A.1 ). Optimal conditions for
anodic fluorination depend on the substrates
used. It is necessary to optimize the
combination of reaction media and supporting
electrolytes.
Anodic fluorination of ethyl phenylthioacetate
proceeds via oxidation of the sulfur atom
followed by deprotonation of its α-position. The
deprotonation step is promoted by the effect of
an electron-withdrawing group substituted at
the α-carbon to the phenylthio group. The
monofluorinated product at the α-position of
the ester group has to be relatively stable if it is
to be used as a building block for further
transformation.