Kinetics and mechanism of electron transfer reactions involving pyridinium chlorochromate and α-hydroxy acids in acid medium catalysed by ruthenium(III)

✍ Scribed by Kishore Kumar; Peyyeti Saroja; Sushama Kandlikar

• Book ID: 104637881
• Publisher: Springer
• Year: 1994
• Tongue: English
• Weight: 379 KB
• Volume: 19
• Category: Article
• ISSN: 0340-4285
• DOI: 10.1007/bf00139113

✦ Synopsis

The oxidation of c~-hydroxy acids (HA), viz. glycolic acid (GA), mandelic acid (MA) and lactic acid (LA), by pyridinium chlorochromate (PCC) in aqueous ethanoic acid solution was investigated in the presence and absence of RuinG13 . The order in [HA] and [PCC] was found to be unity, with or without ruthenium(III) catalyst, and the order in [Ru u~] was found also to be unity. The reaction was acid catalysed also in the presence and absence of ruthenium(III) catalyst, and hence the protonated form of PCC, was assumed to be the active species of oxidant. Added salts, and the change in dielectric constant of the medium, did not affect the oxidation rate. No induced polymerization occurred when acrylamide monomer was added to the reaction mixture. The pseudo-first order rate constants (k'), the formation constants (Kf) of the substrate-catalyst complexes, activation and thermodynamic parameters have been evaluated. Suitable mechanisms in conformity with the experimental observations have been proposed for the uncatalysed and catalysed reactions.