Kinetics and Mechanism of Oxidation of some Substituted trans-Cinnamic Acids by Pyridinium Chlorochromate - A Non-Linear Hammet Plot

Article abstract of DOI:10.1016/S0040-4020(01)85704-5

Kinetics and mechanism of oxidation of some ortho-, para-, and meta-substituted trans-cinnamic acids by pyridinium chlorochromate (PCC) in presence of oxalic acid has been studied.The main product of oxidation is corresponding benzaldehyde and glyoxalic acid.The reaction is first order with respect to and .The oxidation follows fractional order in and +>.The thermodynamic parameters are also determined.Both the electron-releasing and electron-withdrawing substituents, facilitate the rate of oxidation.Correlation with Hammet constants yields a 'V' shaped curve.A suitable mechanism is proposed.In the transition state the formation of carbanion, for electron-withdrawing and carbonium ion for electron releasing substituents is discussed.