Organic Electrode Reactions - Fundamentals and Applications of Organic Electrochemistry - page 135

such reactive anions, highly selective
esterification, etherification and carbonylation
can be achieved at room temperature, as shown
in Eq. 5.12 [27,28].
(5.12)
Cathodic reduction of dioxygen generates
superoxide ion (O 2 − √). Superoxide ion acts as
nucleophile, oxidant, reductant, radical and
base (EGB), therefore this reactive species is
highly useful for organic synthesis. Although
superoxide ions are available from KO 2 and
NaO 2 , these are insoluble in aprotic solvents. In
order to dissolve these salts in aprotic solvents,
costly crown ethers are required therefore their
synthetic applications are limited. On the other
hand, the electrolytic method can generate
superoxide ion in situ , which is better than the
conventional chemical method. As shown in Eq.
5.13 , electrogenerated superoxide ion acts as an
EGB to eliminate the α-proton of malonic ester
derivative, followed by reaction with O 2 to give
the α-hydroxy product in good yield [29]. High
current efficiency suggests that this reaction
may involve a chain reaction.