Redox and acidic properties of the borate radical B(OH)˙4. A flash photolysis study
01 Jan 1989-Journal of the Chemical Society, Faraday Transactions (The Royal Society of Chemistry)-Vol. 85, Iss: 8, pp 2249-2254
TL;DR: Flash photolysis of an aqueous solution of sodium metaborate and potassium peroxydisulphate at pH 115 gives rise to a new transient species with an absorption maxima at 590 nm and 650 nm, respectively.
Abstract: Flash photolysis of an aqueous solution of sodium metaborate and potassium peroxydisulphate at pH 115 gives rise to a new transient species with an absorption maxima at 590 nm (Iµ= 80 m2 mol–1) and 650 nm (Iµ= 90 m2 mol–1) The laser-Raman and 11B nmr spectra of metaborate solutions at pH 115 are consistent with the presence of the tetrahydroxyborate ion, B(OH)–4 The pKa and reduction potential of the radical B(OH)˙4, produced on flashing a mixture of B(OH)–4 and S2O2–8 are found to be 1075 ± 002 and + 14 V, respectively The rate constants for the oxidation of several amines and phenols by this one-electron oxidant have been determined Salt-effect studies are consistent with the reactive species being B(OH)3O˙–
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TL;DR: In this paper, flash photolysis of an aqueous solution of sodium metaborate and potassium peroxydisulphate at pH 11.5 gives rise to a new transient species with an absorption maxima at 590 nm and 650 nm, respectively.
Abstract: Flash photolysis of an aqueous solution of sodium metaborate and potassium peroxydisulphate at pH 11.5 gives rise to a new transient species with an absorption maxima at 590 nm (Iµ= 80 m2 mol–1) and 650 nm (Iµ= 90 m2 mol–1). The laser-Raman and 11B n.m.r spectra of metaborate solutions at pH 11.5 are consistent with the presence of the tetrahydroxyborate ion, B(OH)–4. The pKa and reduction potential of the radical B(OH)˙4, produced on flashing a mixture of B(OH)–4 and S2O2–8 are found to be 10.75 ± 0.02 and + 1.4 V, respectively. The rate constants for the oxidation of several amines and phenols by this one-electron oxidant have been determined. Salt-effect studies are consistent with the reactive species being B(OH)3O˙–.