Kinetics and mechanism of the oxidation of some <img src='/image/spc_char/alpha.gif' border=0> -amino acids by benzyltrimethylammonium tribromide

Abstract

The oxidation of nine <img src='/image/spc_char/alpha.gif' border=0>-amino acids by benzyltrimethylammonium tribromide (BTMAB), in aqueous acetic acid, leads to the formation of the corresponding aldehydes. The reaction is first order with respect to BTMAB. Michaelis-Menten type kinetics are observed with respect to the amino acids. The thermodynamic parameters for the complex formation and the activation parameters for the decomposition of complex have been determined. An addition of benzyl­trimethyl­ammonium ion does not affect the rate. The oxidation of perdeuterioglycine shows the absence of a kinetic isotope effect (<i style="">k</i>_H/<i style="">k</i>_D= 1.05 at 313 K). The effect of solvent composition indicates that the reaction rate increases with an increase in the polarity of the medium. The reaction is susceptible to both polar and steric effects of the substituents. Suitable mechanism has been proposed.