Oxidative Conversion of Lactic Acid by Chloramine-T in Sulfuric Acid Medium: a Kinetic and Mechanistic Study

V S Kiranmai Kolachana,Netkal M Made Gowda,Kishore Cholkar,Waseem M Kayani,R.V Jagadeesh,Gilles K Kouassi

doi:10.5923/j.ajoc.20120201.04

V S Kiranmai Kolachana, Netkal M Made Gowda + Show 4 more

Open Access

https://doi.org/10.5923/j.ajoc.20120201.04

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Abstract

Lactic acid or LA (C3H6O3) plays a major role in several biomedical processes and in organic syntheses. The stoichiometry of the LA-chloramine-T (CAT) reaction in sulfuric acid medium shows that two moles of CAT are consumed per mole of LA with carbon dioxide, acetic acid, and p-toluenesulfonamide (PTS) as main products. The oxidation of LA by CAT in acid solutions has been spectrophotometrically monitored at λmax = 255 nm at 323 K. The reaction, studied under pseudo-first order conditions of (LA)0 >> (CAT)0, follows a first-order dependence of the rate on (CAT) and a fractional order on (LA). Variations of the (PTS), (H + ), (SO4 2- ), dielectric constant, and ionic strength of the reaction medium have no effect on the rate. Kinetic and activation parameters are evaluated based on the temperature effect on the rate. A mechanism consistent with the observed kinetics and activation data has been proposed leading to the derived rate law.

Highlights

Lactic acid (LA) is a naturally occurring organic acid, which is a monomer of polylactic acid
Preliminary results showed that two moles of CAB were consumed per mole of LA resulting in the formation of acetic acid and PTS as the main oxidation and reduction products, respectively
The [H2SO4] has no effect on rate. These results suggest that the free acid species, ArSO2NHCl, is the most likely active oxidizing species involved in the mechanism of LA oxidation

Summary

Introduction

Lactic acid (LA) is a naturally occurring organic acid, which is a monomer of polylactic acid. The focus of the US market is on the production of lactic acid, due to its variety of applications such as in food processing[2], biomedical products[3], and textiles[4] It finds applications in the manufacture of bio-plastics, fibers, solvents, and oxygenated chemicals[1,5,6,7], polymeric lactic acid ester, polylactide (PLA), has a number of biomedical applications in products such as sutures, stents, dialysis media and drug delivery devices[8]. Aromatic sulfonylhaloamines such as chloramine-T (CAT), chloramines-B (CAB), and bromamine-T (BAT) contain a polar N-halo bond, which is capable of forming a halonium (X+) ion in solutions.

Experimental

Results and Discussion

Conclusions