ISSN:
0894-3230
Keywords:
Chemistry
;
Theoretical, Physical and Computational Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Physics
Notes:
The oxidation of several monosubstituted phenoxyacetic acids by pyridinium hydrobromide perbromide (PHPB) was studied in aqueous acetic acid. The reaction is first order with respect to PHPB. Michaelis-Menten-type kinetics are observed with respect to phenoxyacetic acids. The oxidation of [2,2-2H2]phenoxyacetic acid exhibits a substantial kinetic isotopic effect. The effect of solvent composition indicates that the transition state is more polar than the reactants. The formation constants of the intermediate phenoxyacetic acid-PHPB complexes and the rates of their decomposition were determined at different temperatures. The rates of oxidation of para- and meta-substituted phenoxyacetic acids were correlated with Hammett's substituent constants. The ρ value is -2·59 at 35°C. The rates of oxidation of ortho-substituted compounds are correlated with Charton's triparametric equation. A mechanism involving transfer of a hydride ion from the substrate to the oxidant is proposed.
Additional Material:
1 Ill.
Type of Medium:
Electronic Resource
