Kinetic and Analytical Studies of Oxidation of Poly (Vinyl Alcohol) with Ammonium Hexanitratocerate (IV) in Nitric Acid Medium

Abstract

Kinetics of oxidation of poly (vinyl alcohol) is extensively studied to evaluate the thermodynamic parameters and the formation constant (K_ƒ) of the intermediate complex and furthermore to achieve the optimal conditions for analytical determination of poly (vinyl alcohol) in commercially available poly (vinyl alcohol) sample through an established stoichiometry. Second order rate constants obtained in these investigations are utilised to correlate the effects of variation of poly (vinyl alcohol) as a monomer, [Ce(IV)], [H+], ^aNO₃– and added [Ce(III)]. The mechanism of oxidation of poly (vinyl alcohol) involves the formation of a transitory cyclic complex, followed by disproportionation of the complex. The disproportionation of the intermediate complex is the rate determining step. The values for K_f, ΔE^≠, –ΔH^≠, ΔF^≠, ΔS^≠and log A are found to be 15.77 lit. mole^–1, 14.34 Kcal mole^–1, 13.92 Kcal mole^–1, —1.606 Kcal mol^–1 and 41.57 e.u. and 4.5 x 10⁸ sec^–1 respectively.