Pulse radiolysis study on tetra-alkylammonium hydroxides in alkaline solutions containing O2 and N2O

Abstract

The reactivity of the oxide radical ion, O⁻, and the decay kinetics of the ozonide ion, O₃⁻, have been investigated in aqueous solutions at pH 12·8, in the presence of tetramethyl-, tetraethyl-, tetrapropyl- and tetrabutylammonium ions, O₂ and N₂O. Using pulse radiolysis to follow the O₃⁻ kinetics gives information on the competition of O₂ and R₄N⁺ for O⁻. Absolute rate constants for these reactions are: 3·0 × 10⁸ dm³ mol⁻¹ s⁻¹ for O⁻ + (CH₃)₄N⁺, 1·0 × 10⁹ dm³ mol⁻¹ s⁻¹ for O⁻ + (C₂H₅)₄N⁺, 1·3 × 10⁹ dm³ mol⁻¹ s⁻¹ for O⁻ + (C₃H₇)₄N⁺ and 2·2 × 10⁹ dm³ mol⁻¹ s⁻¹ for O⁻ + (C₄H₉)₄N⁺.

The decay of O₃⁻ occurs through the thermal dissociation reaction, O₃ ⇌ O₂ + O⁻, for which the absolute rate constant at 22°C was found to be 6·2 ± 1·2 × 10³ s⁻¹.