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

Abstract

The rate constants of the reactions of e ⁻_aq and the OH^· 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) × 10⁷ and (1.5 ± 0.2) × 10⁷ l mol⁻¹ s⁻¹, respectively. The radical anion ⁻OOC-C^·OO²⁻ 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-COO⁻, the product of the reaction with the OH^· radical, exhibits absorption that has no maximum and increases in intensity with a decrease in the wavelength extending to the UV region (ɛ₂₂₀ = 1800 l mol⁻¹ cm⁻¹). The mechanism of radiation-chemical transformations in aqueous oxalate solutions is discussed.