MECHANISM OF THE OXIDATION OF METHIONINE BY ACID BROMATE

The kinetics of oxidation of DL-methionine by acid bromate has been st udied in aqueous acetic acid (50%, v/v) in the presence of mercuric ac etate which acts as a scavenger for molecular bromine. The reaction wh ich is catalysed by acid shows a first-order dependence on oxidant con centration. The rate constant decreases with increasing methionine con centration suggesting the reversible formation of a 1 : 1 complex betw een the substrate and oxidant. While an increase in dielectric constan t of the medium decreases the rate, an increase in ionic strength perc eptibly enhances the rate of oxidation. Absence of polymerisation of a crylamide excludes the possibility of a radical mechanism. On the basi s of the kinetic observations, a suitable mechanism has been postulate d. Activation parameters have also been evaluated.