OXIDATION OF ALIPHATIC PRIMARY ALCOHOLS BY TETRAKIS (PYRIDINE) SILVER DICHROMATE – A KINETIC AND MECHANISTIC APPROACH
The oxidation of nine aliphatic primary alcohols by tetrakis(pyridine) silver dichromate (TPSD) in dimethylsulfoxide leads to the formation of corresponding aldehydes. The reaction is first order with respect to TPSD. 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 kobs= a + b [H+]. The oxidation of [1,1-2H2]ethanol (MeCD2OH) exhibits a substantial primary kinetic isotope effect (kH/kD = 5.85 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 of the substituents. A suitable mechanism has been proposed.