Kinetics and mechanism of the quinolinium fluorochromate oxidation of someprimary, secondary and unsaturated alcohols in acetonitrile

Quinolinium fluorochromate (QFC) in MeCN readily oxidises primary and secon dary alcohols to the corresponding carbonyl compounds. Solvent effect on re activity is quite significant. The reaction can be characterized by the rat e equation nu = k(3)K(1)K(2)[Alc][TsOH][QFC](t)/ {1 + [TsOH](K-1 + K1K2[Alc ])}. The rho* value ca -1.6 is indicative of a partial bonding in the linea r transition state envisaged. Large primary kinetic isotope effect (k(H)/k( D) > 10) in this study suggests a concerted, two-electron hydride transfer mechanism. Mechanistic studies on the oxidation of unsaturated alcohols wit h QFC in acetonitrile medium described by the rate equation k(0) = k(2)K(1) [TsOH](2) + k(4)K(3)K(1)[Alc][TsOH] is verified. Product analysis studies r ule out the possibility of attack on the double bond. Linear relation in th e Exner plots implies the operation of a common mechanism in all the alcoho ls studied. The high reactivity observed in the cinnamyl alcohol oxidation can be ascribed to resonance interaction through conjugated double bonds.