Second-Order Kinetic Rate Coefficients for the Aqueous-Phase Sulfate Radical (SO₄^•–) Oxidation of Some Atmospherically Relevant Organic Compounds

The sulfate anion radical (SO4•–) is a reactive oxidant formed in the autoxidation chain of sulfur dioxide, among other sources. Recently, new formation pathways toward SO4•– and other reactive sulfur species have been reported. This work investigated the second-order rate coefficients for the aqueous SO4•– oxidation of the following important organic aerosol compounds (kSO4): 2-methyltetrol, 2-methyl-1,2,3-trihydroxy-4-sulfate, 2-methyl-1,2-dihydroxy-3-sulfate, 1,2-dihydroxyisoprene, 2-methyl-2,3-dihydroxy-1,4-dinitrate, 2-methyl-1,2,4-trihydroxy-3-nitrate, 2-methylglyceric acid, 2-methylglycerate, lactic acid, lactate, pyruvic acid, pyruvate. The rate coefficients of the unknowns were determined against that of a reference in pure water in a temperature range of 298–322 K. The decays of each reagent were measured with nuclear magnetic resonance (NMR) and high-performance liquid chromatography–high-resolution mass spectrometry (HPLC-HRMS). Incorporating additional SO4•– reactions into models may aid in the understanding of organosulfate formation, radical propagation, and aerosol mass sinks