KINETICS AND MECHANISM OF NINHYDRIN REACTION WITH COPPER(II) COMPLEXES OF GLYCINE AND ALPHA-ALANINE - ELUCIDATION OF THE TEMPLATE MECHANISM

Ninhydrin has been found to react with Cu(glycine)+ and Cu(alanine)+ i n the ratio of 1:1. The kinetic studies of the reaction were carried o ut at different concentrations of the reactants at 80-degrees-C (pH = 5.0). The reaction proceeds through the formation of a ternary labile complex of ninhydrin with Cu(II) complexes of glycine and alanine. The kinetics were found to follow pseudo-first-order reaction path with r espect to Cu(II)-complex in presence of excess [Ninhydrin]. Formation of a ternary labile complex indicates a template reaction mechanism ba sed on the reactions with coordinated ligands. The variation of pseudo -first-order rate constants with [ninhydrin] was found to be in good a greement with equation 1/k(obs) = B1/[Ninhydrin] + B2 where B1 and B2 are the unknown empirical parameters. The [acetate ion] has no signifi cant effect on the rate constants. On the basis of observed data a pro bable mechanism has been proposed.