Acid-Catalyzed Photooxidation of m-Nitrobenzyl Derivatives ib Aqueous Solution

Article abstract of DOI:10.1021/jo00364a029

A variety of m-nitrobenzyl derivatives including alcohols, alkyl ethers, esters, and an amine undergo photooxidation reactions to produce m-nitrobenzaldehyde (or m-nitroacetophenone in two cases) as the major isolated product.The reaction is both solvent and pH dependent and only takes place in essentially aqueous media.The quantum efficiency of product formation reaches a maximum (φ =0.3-0.4) in the 20-50percent sulfuric acid range, depending on the substrate, although the reaction is reasonably efficient even in neutral aqueous solution.The presence of benzylic hydrogen and a heteroatom (O,N) in the α-position appears to be essential for photooxidation to occur.The multiplicity of the reactive state is T₁.A solvent isotope effect (φ_H2O/φ_D2O = 1.4) was observed.The proposed mechanism involves rate-determining protonation of T₁ followed by rapid α-hydrogen abstraction by water.