A pulse radiolysis study of the oxidation of Br− by Cl2˙− in aqueous solution: formation and properties of ClBr˙−

Abstract

The oxidation of Br⁻ by Cl₂˙⁻ is investigated by pulse radiolysis in aqueous solutions of NaCl and NaBr. Depending on the ratio of the concentration of Br⁻ to Cl⁻, the main product being observed is either Cl₂˙⁻, ClBr˙⁻ or Br₂˙⁻. The mixed radical anion ClBr˙⁻ exhibits a broad absorption band at 350 nm with ε₃₅₀ = 9300 dm³ mol⁻¹ cm⁻¹. The rate constants of the equilibrium Cl₂˙⁻ + Br⁻ ⇌ ClBr˙⁻ + Cl⁻ are determined to be k_f = 4 × 10⁹ and k_b = 1.1 × 10² dm³ mol⁻¹ s⁻¹.