Kinetics of Acidic Potassium Permanganate Oxidation of Formaldehyde in Aqueous and 5% Ethanol-Water Solvents.

Abstract

Kinetics of acidic Mn(VII) oxidation of Formaldehyde in aqueous and 5% ethanol-water solvents were studied via pseudo-first order condition at λmax 525nm. The reaction showed a first order dependence with respect to formaldehyde concentration, [Mn(VII)], first order to [H+ ] and independent on the ionic strength of the solution. Michaelis-Menten plot showed the existence of an intermediate complex. However, oxidation reaction is generally faster in non-aqueous solvent than in aqueous solvent. Product analysis revealed the presence of carboxylic acid and stoichiometric study suggests the consumption of 2 moles of MnO4 - by 3 moles of formaldehyde in both solvents. Thermodynamic parameters of activation were obtained from Arrhenius and Erying’s equations. A plausible associative mechanism in agreement with kinetic and spectroscopic results was proposed.