Kinetic Istotope Effect Studies in the Oxidation of Benzhydrols by Hexavalent Chromium in Absence and in Presence of Oxalic Acid

Department of Chemistry, R. K. M. Vivekananda. College, Madras- 600 004 Kinetic deuterium isotope effect studies have been made on the oxidation of a number of benzhydrols by potassium dichromate both in absence of and in presence of oxalic acid. The substituent effect on the kinetic isotope effect as also the temperature effect on the kinetic isotope effect have been analysed and the structure and geometry of the transition state of these reactions have been delineated. The reactions exhibit a considerably lowered kH/kD values in the presence oxalic acid indicating a direct transition from CrVI to CrIll in the cooxidation reaction. Added 2.-hydroxy-2-methylbutyric acid (HMBA) fails to Increase the rate of oxidation of benzhydrol by CrVI