Oxidation of Substituted Benzyl Alcohols by Pyridinium Fluorochromate: A Kinetic Study

Article abstract of DOI:10.1021/jo00245a004

The kinetics of the oxidation of 30 monosubstituted benzyl alcohols to the corresponding benzaldehydes by pyridinium fluorochromate (PFC) have been studied.The reaction is first order with respect to PFC.A Michaelis-Menten type kinetics was observed with respect to the substrate, indicating the formation of a PFC-alcohol complex in the preequilibrium.The formation constants and the rates of disproportionation of the complexes were determined.The oxidation of <α,α-(2)H2>benzyl alcohol indicated the presence of a substantial primary kinetic isotope effect.The ratesof the decomposition of the complexes of the meta-and para-substituted alcohols were analyzed in terms of Taft's and Swain's dual substituent parameter equations.The meta compounds showed an excellent correlation with Taft's ?_I and ?_R⁰ values while the para-substituted compounds correlate with ?₁ and ?_R^BA constants.The rates of the ortho-substituted alcohols correlate with Charton's equation of inductive, resonance, and steric paramaters.The reaction was studied in 19 solvents.The correlation analysis of the solvent effect indicated the greater importance of the cation-solvating power of the solvent.The reaction involves a hydride ion transfer in the rate-determining step.

Full text of DOI:10.1021/jo00245a004

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Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.

Evaluation Only. Created with Aspose.PDF. Copyright 2002-2021 Aspose Pty Ltd.