Kinetics and mechanism of oxidation of l-serine by tetrachloroaurate (iii) in sodium acetate-acetic acid buffer

The kinetics of oxidation of L-serine by gold(III) was studied spectrophotometrically at 313 nm in sodium acetate – acetic acid buffer. The reaction is first order in tetrachloroaurate(III) and fractional order with respect to L-serine. A mechanism consistent with th kinetic data has been proposed where [AuCl3(OH)]- was presumed to be the reactive species of gold(III). The reaction product 2-hydroxy acetaldehyde was identified by 1 H NMR spectroscopy and 13 C NMR spectroscopy. The mechanism proposed leads to the rate equation:

The activation parameters have been determined to be Ea =28.35 ± 1.68 kJ mol-1 andΔS# = -194.43 ± 4.21 JK-1 mol-1 respectively.