Kinetics and mechanism of oxidation of alpha-hydroxy acids by quinolinium dichromate

摘要

Kinetics and mechanism fo alpha-hydroxy acids (lactic and mandelic acid) by quinolinium dichromate(QDC) have been studied in aqueous-acetic acid medium.The reaction is first order each in [QDC],[alpha-hydroxy acid] and [HClO_4].The rate of reaction increases with decrease in solvent polarity.Various thermodynamic parameters have been evaluated.The reaction proceeds through formation of a cyclic chromic-ester between protonatedquinolinium dichromate and alpha-hydroxy acid,followed by decomposition to aldehyde and CO_2 by C-H bond fission.