EVIDENCE OF ESTERIFICATION DURING THE OXIDATION OF SOME AROMATIC ALDEHYDES BY CHROMIUM (VI) IN ACID MEDIUM AND THE MECHANISM OF THE OXIDATION PROCESS

Article abstract of DOI:10.1016/S0040-4020(01)82024-X

The oxidation kinetics of some aromatic aldehydes by chromium (VI) have been studied in perchloric acid medium.Kinetic and spectrophotometric results indicate the formation of a 1:1 intermediate ester between the reactive chromium (VI) species and protonated benzaldehyde.The rate is directly proportional to the square of hydrogen ion concentrations.The rate of oxidation decreases with the presence of electron donating groups and increases with electron withdrawing groups on the aromatic ring.The activation parameters associated with the rate determining step and the thermodynamic values associated with the equilibrium step have been computed.An attempt has been made to compare the results obtained with those for the oxidations of some aliphatic aldehydes which do not have enolizable hydrogen.