Pulse radiolysis of methanol and ethanol. Acid-base behaviour of hydroxymethyl and hydroxyethyl radicals

Abstract

Pulse radiolysis of N₂O saturated alkaline methanolic and ethanolic solutions indicates that at room temperature the equilibria R¹R²ĊOH + R¹R²CHO^–⇌ R¹R²ĊO^–+ R¹R²CHOH (2) are rapidly established with K₂= 2120 ± 235 and 3280 ± 340 for ·CH₂OH and CH₃ĊHOH radicals in their respective parent solvents. The decays of the radical anions obey second-order rate laws in both solvents and rate constants have been obtained for the bimolecular reactions involving the neutral and basic forms of the radicals.

Experiments with ethanolic acetaldehyde solutions indicate that k_–2 > 6 × 10⁶ dm³ mol^–1 s^–1 and hence k₂ > 1.8 × 10¹⁰ dm³ mol^–1 s^–1.