Oxidative Conversion of Lactic Acid by Chloramine-T in Sulfuric Acid Medium: a Kinetic and Mechanistic Study

Lactic acid or LA (C3H6O3) plays a major role in several biomedical processes and in organic syntheses. The stoichiometry of the LA-chloramine-T (CAT) reaction in sulfuric acid medium shows that two moles of CAT are consumed per mole of LA with carbon dioxide, acetic acid, and p-toluenesulfonamide (PTS) as main products. The oxidation of LA by CAT in acid solutions has been spectrophotometrically monitored at λmax = 255 nm at 323 K. The reaction, studied under pseudo-first order conditions of [LA]0 >> [CAT]0, follows a first-order dependence of the rate on [CAT] and a fractional order on [LA]. Variations of the [PTS], [H+], [SO42-], dielectric constant, and ionic strength of the reaction medium have no effect on the rate. Kinetic and activation parameters are evaluated based on the temperature effect on the rate. A mechanism consistent with the observed kinetics and activation data has been proposed leading to the derived rate law.