Pulse radiolysis of aqueous solutions of tetraphenylphosphonium ions

Abstract

The reactions of tetraphenylphosphonium ion (Ar 4P +) with e aq −, H atoms and OH radicals have been investigated. The absorption spectra of three transient species were obtained. Ar 4P· radicals formed by the reaction: Ar 4P + + e aq − → Ar 4P· have a maximum absorption at 305 nm [ ε 305 = (9400 ± 300) dm 3 mol −1 cm −1] and decays by second-order kinetics with the rate constant 2 k = (2·7 ±0·4) × 10 9 dm 3 mol −1 s −1. H atoms and OH radicals form transient adducts to the phenyl groups of the Ar 4P + ion with the rate constants of (1·5 ± 0·3) × 10 9 dm 3 mol −1 s −1 and (3·0±0·3) × 10 9 dm 3 mol −1 s −1, respectively. Both adducts have broad absorption spectra at 300≈380 nm ( λ max = 340 nm) with the molar extinction coefficients ε 340 = 5400±300 dm 3 mol −1 cm −1 for the H adduct and ε 340 = 3500±200 dm 3 mol −1 cm −1 for the OH adduct.