A pulse radiolysis study of the reactions of the hydrated electron and hydroxyl radical with the oxalate ion in neutral aqueous solution

摘要

The rate constants of the reactions of e(aq)(-) and the OH center dot radical with the oxalate ion in a neutral aqueous solution were measured by means of the pulse radiolysis technique. They were found to be (3.5 +/- 0.5) x 10(7) and (1.5 +/- 0.2) x 10(7) l mol(-1) s(-1), respectively. The radical anion -OOC-C (OO2-)-O-center dot is characterized by an optical absorption band that has a maximum at 270 nm and a molar absorption coefficient of (2400 +/- 200) l mol(-1) cm(-1). The radical anion (OOC)-O-center dot-COO-, the product of the reaction with the OH center dot radical, exhibits absorption that has no maximum and increases in intensity with a decrease in the wavelength extending to the UV region (epsilon(220) = 1800 l mol(-1) cm(-1)). The mechanism of radiation-chemical transformations in aqueous oxalate solutions is discussed.