Pulse Radiolysis of Aqueous Solutions of Benzyltrialkylammonium Cations. Reactions with the Primary Transients from Water Radiolysis

Article abstract of DOI:10.1021/j150604a016

The primary reactions of hydrogen atoms, hydrated electrons, hydroxyl radicals, and oxide radical ions with benzyltrimethylammonium cations in aqueous solutions have been studied by the technique of pulse radiolysis.Hydrogen atoms react with the rate constant (2.0 +/- 0.1) X 10⁹ M^-1 s^-1.The cyclohexadienyl-type radical decayed in a second-order process with a rate constant 2k = (4.8 +/- 0.2) X 10⁹ M^-1 s^-1.Hydrated electrons react with a rate constant (4.3 +/- 0.2) X 10⁹ M^-1 s^-1 to form benzyl radical.It has been concluded that irradiation of benzyltrimethylammonium cations results in deamination brought about by hydrated electrons.Hydroxyl radicals react with benzyltrimethylammonium cation with a rate constant (5.0 +/- 0.6) X 10⁹ M^-1 s^-1 to form the cyclohexadienyl-type radical HOC6H5CH2N⁺(CH3)3 (ca.65percent) and C6H5C^.HN⁺(CH3)3 (ca.35percent) radicals.The cyclohexadienyl radical has a broad absorption maximum at 325 nm (ε ca. 3300 M^-1 cm^-1).Oxide radical ions react with the rate constant (5.9 +/- 0.5) X 10⁸ M^-1 s^-1 to form C6H5C^.HN⁺(CH3)3 with absorption maxima at 260 and 305 nm.With the increasing chain length of the alkyl substituent (as in the benzyltri-n-butylammonium cation) the reaction of hydrogen abstraction from the alkyl groups becomes more important.