Kinetics and Mechanism of Oxidative Decarboxylation of α-Amino Acids by Dichloramine-B in Aqueous Acetic Acid

Department of Post-Graduate Studies and Research in Chemistry, Mangalore University, Mangalagangothri-574 199 

Manuscript received 22 November 1991, revised 24 August 1992, αccepteα 24 September 1992

Kinetics of oxidation of several α-amino acids (AA) by dichloramine-B have been studied in aqueous acetic acid in presence of perchloric acid. The rates of oxidations show two ranges in [HCIO₄] with zero and inverse fractional order in [H⁺]. The reactions generally show second order kinetics in [DCB] in both the acid ranges and fractional order in [AA], although the magnitudes of the fractional orders are different Oxidations of some amino acids have also been investigated in the presence of sodium acetate. Under these conditions the rates are independent of [AA] The results indicate the participa­tion of acetate ions in the reaction in addition to the secondary salt effect. Increase in acetic acid composition of the solvent decreases the rates of oxidations. Two-pathway mechanisms consistent with observed results have been considered. The coefficientsof the rate-limiting steps at different temperatures and the corresponding activation parameters are also computed.