Kinetics of a-Amino Acids Acylation by p-Nitrophenyl p-Nitrobenzoate in Water-propan-2-ol mixtures

Abstract

Kinetic studies of α-amino acids acylation by p-nitrophenyl p-nitrobenzoate in water-propan-2-ol mixtures were carried out at different temperatures under pseudo-first conditions by keeping the concentration of α-amino acid in thirty fold excess over that of the p-nitrophenyl p-nitrobenzoate. We can put the investigated α-amino acids in the following order according to their reacting ability in the acylation reaction : L-proline>>glycine>L-α-alanine>L-valine>L-serine>DL-threonine. Increase of the water content in the binary water-propan-2-ol solvent leads to a decrease of energy,enthalpy and entropy of activation. The positive effect of water with its high dielectric constant on the rate of a-amino acids acylation was discussed.