Kalyan K Banerji

Kinetics and mechanism of the oxidation of some neutral and acidic α-amino acids by tetrabutylammonium tribromide

The oxidation of eleven amino acids by tetrabutylammonium tribromide (TBATB) in aqueous acetic acid results in the formation of the corresponding carbonyl compounds and ammonia. The reaction is first order with respect to TBATB. Michaelis-Menten type kinetics is observed with some of the amino acids while others exhibit second-order dependence. It failed to induce polymerization of acrylonitrile. The effect of solvent composition indicate that the rate of reaction increases with increase in the polarity of the medium. Addition of tetrabutylammonium chloride has no effect on the rate of oxidation. Addition of bromide ion causes decrease in the oxidation rate but only to a limiting value. The reaction is susceptible to both polar and steric effects of the substituents. A suitable mechanism has been proposed

Kinetics and mechanism of oxidation of aliphatic primary alcohols by quinolinium bromochromate

Oxidation of nine aliphatic primary alcohols by quinolinium bromochromate (QBC) in dimethylsulphoxide leads to the formation of the corresponding aldehydes. The reaction is first order with respect to both QBC and the alcohol. The reaction is catalysed 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. 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.

Kinetics and mechanism of the oxidation of formic acid bybis-(2,2′-bipyridyl) copper(II) permanganate

The oxidation of formic acid bybis-(2,2′-bipyridyl)copper(II) permanganate (BBCP) is first order with respect to BBCP. The order with respect to formic acid is less than one in the absence of perchloric acid whereas in the presence of perchloric acid, it is more than one but less than two. Thus in both the cases Michaelis-Menten type kinetics were observed with respect to formic acid. The overall formation constants for the formic acid-BBCP complexes and their rates of decomposition have been evaluated. Thermodynamic parameters for complex formation and the activation parameters for their decomposition have also been calculated. The hydrogen-ion dependence has the formkobs=a+b[H+]+c[H+]2. The oxidation of deuterioformic acid showed the presence of a primary kinetic isotope effect (kH/kD≈4). An increase in the amount of acetic acid in the solvent mixture, acetic acid and water, increases the rate. The addition of 2,2′-bipyridine and acrylonitrile has no effect on the rate. Suitable mechanisms have been proposed.

Kinetics and mechanism of oxidation of diols bybis(2,2′-bipyridyl) copper(II) permanganate

Kinetics of oxidation of five vicinal, four non-vicinal diols, and one of their monoethers bybis(2,2′-bipyridyl) copper(II) permanganate (BBCP), has been studied. The vicinal diols yielded the products arising out of the glycol bond fission, while the other diols yielded the hydroxycarbonyl compounds. The reaction is first-order with respect to BBCP. Michaelis-Menten type kinetics were observed with respect to the diol. There is no effect of added 2,2′-bipyridine on the reaction. The oxidation of [1,1,2,2-2H4] ethanediol showed the absence of a primary kinetic isotope effect. A mechanism involving a glycol bond fission has been proposed for the oxidation of the vicinal diols. The other diols are oxidised by a hydride-transfer mechanism as are monohydric alcohols.

Kinetic study of the oxidation of aliphatic aldehydes bybis(2,2′-bipyridyl) copper(II) permanganate

Kinetics of oxidation of aliphatic aldehydes, to the corresponding carboxylic acids, by bis(2,2′-bipyridyl)copper(II) permanganate (BBCP) has been studied. The reaction is first order with respect toBBCP. Michaelis-Menten type kinetics were observed with respect to the aldehyde. The formation constants for the aldehyde-BBCP complexes and the rates of their decomposition, at different temperatures, have been evaluated. Thermodynamic parameters for the complex formation and the activation parameters for their decomposition have also been determined. The reaction is catalysed by hydrogen ions; the acid-dependence being of the form:kobs = a +b [H+]. The oxidation of MeCDO exhibited a substantial kinetic isotope effect (kH/kD = 4.33 at 303 K). The role of aldehyde hydrate in the oxidation process has been discussed. A mechanism involving formation of permanganate ester and its slow decomposition has been proposed.