title: Suitable combination of promoter and micellar catalyst for kilo fold rate acceleration on benzaldehyde to benzoic acid conversion in aqueous media at room temperature: a kinetic approach.
abstract: The kinetics of oxidation of benzaldehyde by chromic acid in aqueous and aqueous surfactant (sodium dodecyl sulfate, SDS, alkyl phenyl polyethylene glycol, Triton X-100 and N-cetylpyridinium chloride, CPC) media have been investigated in the presence of promoter at 303 K. The pseudo-first-order rate constants (kobs) were determined from a logarithmic plot of absorbance as a function time. The rate constants were found to increase with introduction of heteroaromatic nitrogen base promoters such as Picolinic acid (PA), 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). The product benzoic acid has been characterized by conventional melting point experiment, NMR, HRMS and FTIR spectral analysis. The mechanism of both unpromoted and promoted reaction path has been proposed for the reaction. In presence of the anionic surfactant SDS, cationic surfactant CPC and neutral surfactant TX-100 the reaction can undergo simultaneously in both aqueous and micellar phase with an enhanced rate of oxidation in the micellar phase. Both SDS and TX-100 produce normal micellar effect whereas CPC produce reverse micellar effect in the presence of benzaldehyde. The observed net enhancement of rate effects has been explained by considering the hydrophobic and electrostatic interaction between the surfactants and reactants. SDS and bipy combination is the suitable one for benzaldehyde oxidation.
authors.affiliation: Homogeneous Catalysis Laboratory, Department of Chemistry, The University of Burdwan, Golapbag, Burdwan, 713 104 WB, India.
authors.forename: Aniruddha
authors.initials: A
authors.lastname: Ghosh
authors.forename: Rumpa
authors.initials: R
authors.lastname: Saha
authors.forename: Sumanta K
authors.initials: SK
authors.lastname: Ghosh
authors.forename: Kakali
authors.initials: K
authors.lastname: Mukherjee
authors.forename: Bidyut
authors.initials: B
authors.lastname: Saha
mesh_terms: D015082:2,2'-Dipyridyl / Q000737:chemistry; D001547:Benzaldehydes / Q000737:chemistry*; D019817:Benzoic Acid / Q000737:chemistry*; D002384:Catalysis; D002594:Cetylpyridinium / Q000737:chemistry; D002857:Chromium / Q000737:chemistry*; D007700:Kinetics; D008823:Micelles; D010084:Oxidation-Reduction; D010618:Phenanthrolines / Q000737:chemistry; D011092:Polyethylene Glycols / Q000737:chemistry; D012967:Sodium Dodecyl Sulfate / Q000737:chemistry; D013501:Surface-Active Agents / Q000737:chemistry*
chemical_list: D001547:Benzaldehydes; D008823:Micelles; D010618:Phenanthrolines; D013501:Surface-Active Agents; C551282:polyethylene glycol monooctylphenyl ether; D002857:Chromium; C074702:chromium hexavalent ion; D012967:Sodium Dodecyl Sulfate; D011092:Polyethylene Glycols; D015082:2,2'-Dipyridyl; D019817:Benzoic Acid; D002594:Cetylpyridinium; C032175:benzaldehyde; C025205:1,10-phenanthroline