Micellar and Polymer Catalysis in the Kinetics of Oxidation of L-lysine by Permanganate Ion in Perchloric Acid Medium

Mohammed Hassan,Ahmad A Najjar,Mohammad Al-Dhoun,Qutaiba A Ibrahim,Yazan Batineh,Adnan Dahadha

doi:10.17159/0379-4350/2021/v75a8

Abstract

ABSTRACT Kinetics of oxidation of L-lysine by permanganate ion in a perchloric acid medium was investigated to explore the order of the reaction with respect to oxidant and substrate and to study the catalytic behaviour of sodium lauryl sulphate (SLS) and polyethylene glycol (PEG). The reaction was found to be first-order with respect to the oxidant and the substrate and zero-order with respect to hydrogen ion. Changes in the sodium sulphate concentration produce a non-significant variation in the rate of the reaction. SLS and PEG were found to catalyze the reaction. Surfactant catalysis was modelled by Piszkiewicz's cooperativity model, while polymer catalysis was explained with the help of the Benesi-Hildebrand equation. The temperature dependence of the rate of the reaction was elucidated, and activation parameters were obtained. Interestingly, the reaction was found to possess positive activation entropy indicating the dissociative nature of the transition state and outer-sphere electron transfer mechanism. A mechanism of the reaction that is supported by the experimental findings was suggested. Keywords: L-lysine, permanganate ion, micellar catalysis, polymer catalysis, outer sphere electron transfer mechanism.

Highlights

Oxidation of lysine in its biological form is important and is related to nuclear sclerosis of the lens of the eye and other disorders.[1,2] Due to lysine and other amino acids’ functional role, the oxidation kinetics, with different metal ion oxidants, are of special interest and have undergone extensive investigation.[3,4,5,6] One of the metal ion oxidants of interest is the permanganate heptavalent ion
We investigated the kinetics of the permanganate ion oxidation of L-lysine in a perchloric acid medium
There is no observable shift in the position of the three bands of permanganate ion, which indicates that the electron transfer reaction between the oxidant and substrate occurs through the outer-sphere mechanism rather than the inner sphere mechanism that involves the formation of a covalent oxidant-substrate complex.[18]

Summary

Introduction

Oxidation of lysine in its biological form is important and is related to nuclear sclerosis of the lens of the eye and other disorders.[1,2] Due to lysine and other amino acids’ functional role, the oxidation kinetics, with different metal ion oxidants, are of special interest and have undergone extensive investigation.[3,4,5,6] One of the metal ion oxidants of interest is the permanganate heptavalent ion It is a powerful oxidizing agent and has been used extensively in the oxidation of organic substrates. Polymeric materials that are soluble in an aqueous solution are of particular interest since they must have many hydrophilic moieties, leading to a more significant role in the catalysis reaction One of these polymeric materials is polyethylene glycol (PEG), which has attracted the attention of several researchers studying catalytic behaviour.[13,14] In this study, we investigated the kinetics of the permanganate ion oxidation of L-lysine in a perchloric acid medium. Exploring micellar and polymer catalysis will increase the knowledge about the catalytic behaviour of these interesting chemical species

Experimental

Results and Discussion

Reaction Order with respect to L-lysine

Effect of Temperature

Conclusion