Quinolinium dichromate oxidation of aliphatic aldehydes. A kinetic study

Kinetic data on the rates of quinolinium dichromate oxidation of a series of aliphatic aldehydes have been determined and discussed with reference to aldehyde hydration equilibria. A value of rho* = -1.63 for the oxidation of aldehyde hydrates was obtained. Kinetic results supported a pathway proceeding via a rate-determining oxidative decomposition of the chromate ester of the aldehyde hydrates. A cyclic transition state has been suggested; being a Huckel-type system (4n + 2), this would be an allowed process. The deuterium isotope effect for the oxidation of acetaldehyde-d(1) (k(H)/k(D) = 6.4) indicated a carbon-hydrogen bond cleavage rather than a carbon-carbon bond cleavage.