Superoxide anion, reactions electrochemical

An electrosynthetic approach to 2-nitroalcohols via activation of nitromethane by electrogenerated superoxide anion has been reported by Evans et al. [166-168]. Recently, the electrochemically induced Henry reaction has been performed via direct cathodic reduction of nitromethane (Scheme 16.28) [169, 170]. 

The reaction of alkyl isothiocyanates, RNCS, with diphenylphosphinic hydrazide (338) in benzene has been reported.308 The bis(diethylamino)[(methylthio)thiocarbon-yl]carbenium salts (339 X = I or BF4) display ambident reactivity and can react either at carbenium carbon (hard nucleophiles) or at the thiocarbonyl sulfur atom (soft nucleophiles).309 Electrochemically generated superoxide reacts with dithioic S,S -diesters (dicarbothiolates) (340 Ar = C5H3N or C6H4) to give the monocarboxylate anions in 100% yield before giving the dicarboxylate anions.310... 

Both donor and acceptor molecules are indispensable for the accomplishment of the photoredox reaction and the electrochemical potentials of the donor (D/D +) and acceptor (A/A" ) couples should lie within the semiconductor band gap. Oxidation reactions, photocatalysed by Ti02, are usually performed in the presence of easily reducible molecular oxygen as an electron acceptor, thereby generating a superoxide radical ion (02 ) and subsequently hydroxyl radicals. The resulting holes on the semiconductor surface can oxidize many compounds (Scheme 6.292), including alcohols, hydroxyl anion and even water.1522,1523... 

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