Reactions of aliphatic free radicals with copper cations in aqueous solutions. Part 3.—Reactions with cuprous ions: a pulse radiolysis study
Abstract
Helium-saturated solutions containing copper sulphate and an aliphatic alcohol (methanol, ethanol or propan-2-ol) were pulse irradiated. The kinetics of the reactions thus initiated were followed by the spectrophotometric and conductometric techniques. The results indicate that all three radicals, ·CR1R2OH, react with Cu2+aq to yield Cu+aq+ CR1 R2O + H3O+. ·CH2OH radicals react with Cu+aq according to Cu+aq+·CH2OH ⇄ CuII—CH2OH+, K≈ 5 × 103 dm3 mol–1. The corresponding equilibrium constants for CuII—CH(CH3)OH+ and CuII—C(CH3)2OH+ are too low to be measured and the corresponding intermediates are not observed. Cu+aq reacts with the β radicals, ·CH2CH2OH and ·CH2CH(CH3)OH, according to Cu+aq+·CH2CR1R2OH → CuII—CH2CR1R2OH+. The latter intermediates decompose via acid catalysed reactions to yield Cu2+aq+ H2CCR1R2+ H2O.