Abstract

K. R. Sankaran and C. K. P. Paramasundari

The pyridinium fluorochromate {(Cr(VI)}, oxidation of pentaamminecobalt (III) bound and unbound mandelic and lactic acids have been studied both in the absence and the presence of oxalic acid. The reaction exhibits total second order kinetics - first order with respect to Co (III) complex/a-hydroxy acids and PFC. Cobalt (III) bound and unbound a-hydroxy acids get oxidised at comparable rates, ligation of carboxylic acid to cobalt (III) centre does not exert any electrostatic influence on the seat of attack, possibly the a-C-H bond.The addition of oxalic acid (OxH2) increases the rate of pyridinium fluorochromate co-oxidation of OxH2 and cobalt (III) bound complexes of a-hydroxy acids and unbound ligand also. The formation of respective keto acids/ketoacid - cobalt (III) complex as the product of the reaction is accounted by a suitable mechanism.

pyridinium; fluorochromate; pentaamminecobalt mechanism

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