Collect. Czech. Chem. Commun. 2001, 66, 877-896

Kinetics and Mechanism of the Quinolinium Fluorochromate Oxidation of Some Primary, Secondary and Unsaturated Alcohols in Acetonitrile

Subbiah Meenakshisundaram* and Ramanathan Sockalingam

Department of Chemistry, Annamalai University, Annamalainagar-608 002, India


Quinolinium fluorochromate (QFC) in MeCN readily oxidises primary and secondary alcohols to the corresponding carbonyl compounds. Solvent effect on reactivity is quite significant. The reaction can be characterized by the rate equation v = k3K1K2[Alc][TsOH][QFC]t/ {1 + [TsOH](K1 + K1K2[Alc])}. The ρ* value ca -1.6 is indicative of a partial bonding in the linear transition state envisaged. Large primary kinetic isotope effect (kH/kD > 10) in this study suggests a concerted, two-electron hydride transfer mechanism. Mechanistic studies on the oxidation of unsaturated alcohols with QFC in acetonitrile medium described by the rate equation k0 = k2K1[TsOH]2 + k4K3K1[Alc][TsOH] is verified. Product analysis studies rule out the possibility of attack on the double bond. Linear relation in the Exner plots implies the operation of a common mechanism in all the alcohols studied. The high reactivity observed in the cinnamyl alcohol oxidation can be ascribed to resonance interaction through conjugated double bonds.

Keywords: Alcohols; Quinolinium fluorochromate; Chromates; Oxidations; Aldehydes; Reaction kinetics; Reaction mechanisms; Solvent effects.

References: 47 live references.