Selective oxidation of primary alcohols mediated by nitroxyl radical in aqueous solution. Kinetics and mechanism

Article abstract of DOI:10.1016/0040-4020(95)00417-7

The kinetics of the TEMPO-mediated oxidation of methyl α-D- glucopyranoside to sodium methyl α-D-glucopyranosiduronate were studied. An intermediate was found which was identified as the hydrated aldehyde. This was oxidised in the same manner as the alcohol, with pseudo first order rate constants ratio k(obs,ald)/k(obs,alc) = 7. The reaction mechanism is discussed with emphasis on steric factors and compared to literature data. Two different reaction pathways are postulated; under basic reaction conditions via a cyclic transition state 3 and under acid reaction conditions through an acyclic transition state 4.