Electrochemical reduction acyl halides

In general, the dissolving metal or electrochemical reductions of acyl halides or acyclic anhydrides are not useful for the preparation of primary alcohols. Such reductions invariably provide acyloin esters, ene-diolate diesters or related species. Cyclic anhydrides may be reduced to give lactones. For example, the reduction of phthalic anhydride at a mercury cathode has been used in the synthesis of phthalide (90%). In general, however, such reduction are not widely employed in synthesis. 

An interesting coupling of acyl halide with Michael acceptors involves an organo-metallic intermediate and photochemical step as well as an electroreduction. The electrochemical reduction, however, is used to reduce the intermediate cobalt oxidation state [115]. 

Most organic reactions are Lewis acid/base processes that involve the interaction of a nucleophilic center with an electrophilic center. Because electrochemistry provides the ultimate nucleophile via the electrons at the cathode surface and the ultimate electrophile via the electron holes at the anode surface, it is the ideal methodology for the characterization of the electrophilicity and nucleophilic-ity of molecules. Thus, the carbon centers of saturated hydrocarbons (e.g., CH4) are resistant to electrochemical reduction and oxidation because of their inert nature (all valence electrons are stabilized in sigma bonds an absence of any Lewis acid/base character). However, organic molecules with electrophilic components [e.g., alkyl-, aryl-, and acyl- halides carbonyl groups unsaturated and aromatic hydrocarbons nitro groups Brpnsted... 

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