Combination of Sodium Dodecylsulfate and 2,2′-Bipyridine for Hundred Fold Rate Enhancement of Chromium(VI) Oxidation of Malonic Acid at Room Temperature: A Greener Approach

Abstract

Chromic acid oxidation of malonic acid in aqueous media has been investigated spectrophotometrically at 303 K. The product glyoxylic acid has been characterized by 13 C-NMR and FTIR spectroscopy. Three representative N-heteroaromatic nitrogen base promoters, 2-picolinic acid, 2,2 0 -bipyridine (bpy) and 1,10-phenanthroline, in combination with the anionic surfactant sodium dodecylsulfate (SDS) enhanced the rate of the oxidation reaction compared to the unpromoted reaction. 2,2 0 -Bipyridine produced the maximum rate enhancement of the three promoters used. The mechanism of the reaction has been proposed with the help of kinetic results and spectroscopic studies. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. The SDS and bpy combination is suitable for malonic acid oxidation.

Novel Amphiphiles and Their Applications for Different Purposes with Special Emphasis on Polymeric Surfactants

“…Sometimes, hetero‐aromatic nitrogen bases or metal salts also can be used as promoter for some additional rate enhancement of the surfactant catalysed reactions . Though, it is not also unprecedented where cationic surfactants e. g. CPC reduces reaction rate.…”

Employment of different spectroscopic tools for the investigation of chromium(VI) oxidation of acetaldehyde in aqueous micellar medium

“…fast kinetics, with satisfactory high yield of product, which requires no supplement of extreme and drastic condition proved it to be a greener approach. 23 There has been a flow of interest on catalysis of reactions by surfactant micelles with a view of their extensive applications in chemical, industrial, pharmaceutical, environmental and biological fields. [24][25][26] A systematic study of associated systems comprising electron transfer reaction and micelle formation process of surfactants might therefore be helpful to understand the electron transport system in catalysis.…”

“…The existence of Cr(III) in the product mixture was established from the absorption maximum at 580 nm in this work and also supported from earlier reports. 16,23,30 The stoichiometry of the reaction was determined by spectrophotometric titration. Several kinetic runs were carried out by taking [acetaldehyde] >>[chromium(VI)] at fixed [H + ] and kept the reaction mixture for 48 h at 30 • C. After completion of the reaction, the unconsumed oxidant was determined spectrophotometrically.…”

“…As a consequence the local concentration effect of the reactant molecule in the Stern-region of SDS micelle significantly participate to increase the rate of reaction in SDS micellar medium than that in aqueous medium. 23 The hydrophilic interaction between nonionic (TX-100) micelle and either reactants or reaction intermediate and local concentration effect appeared to be the probable source of micellar catalysis.…”

“…The active oxidant Cr(VI)-phen complex reacts with the substrate to form a ternary complex which experiences a redox decomposition in a rate determining step giving rise to the organic product. 12,23 As Cr(VI)-phen is a giant molecule, electrostatic attraction is not operating smoothly. For promoted reaction path, the rate is maximum in TX-100 followed by SDS (Table S1 in SI).…”