Kinetics and mechanism of the oxidation of aliphatic primary alcohols by imidazolium fluorochromate

Chemical Kinetics Laboratory, Department of Chemistry, J. N. V. University, Jodhpur-342 005,
Rajasthan, India
E-mail : drpkvs27@yahoo.com
Manuscript received 06 April 2010, revised 15 September 2010, accepted 16 September 2010

The oxidation of nine aliphatic primary alcohols by imidazolium fluorochromate (IFC) in dimethylsulphoxide leads to the formation of corresponding aldehydes. The reaction is first order with respect to IFC. A Michaelis-Menten type kinetics is observed with respect to alcohols. The reaction is promoted by hydrogen ions; the hydrogen-ion dependence has the form : k_obs = a + b [H⁺]. The oxidation of [1,1-²H₂]ethanol (MeCD₂OH) nhibits a substantial primary kinetic isotope effect (k_h/k_d = 5.87 at 298 K). The reaction has been studied in nineteen different organic solvents. The solvent effect was analysed using Taft's and Swain's multiparametric equations. The rate of oxidation is susceptible to both polar and steric effects or the substituents. A suitable mechanism has been proposed.