Atmospheric reactions of hydroperoxymethyl thioformate with sulfur trioxide catalyzed by water monomer and hydrolysis of sulfur trioxide catalyzed by hydroperoxymethyl thioformate

Abstract

Hydroperoxymethyl thioformate (HPMTF) is an important compound in the atmosphere. However, its atmospheric sinks are incompletely unknown. Here, we study the reactions of HPMTF + SO3 and HPMTF + SO3 + H2O using high-level quantum chemical methods and dual-level strategy for kinetics calculations. Our present findings suggest that water has a remarkably catalytic role in HPMTF + SO3 + H2O → CHOSCH2OOS(H)O3 + H2O, as the enthalpy of activation at 0 K for HPMTF + SO3 is significantly decreased by 29.17 kcal/mol due to the introduction of H2O. The present results also uncover that the calculated rate constant of HOOCH2SCHO ⋯ SO3 + H2O is increased by about 7.7 to 6.1 at 280–350 K due to the effects of vibrational anharmonicity. We also find that the HPMTF + SO3 + H2O reaction can compete well with the HPMTF + OH reaction, significantly contributing to the sink of HPMTF during the nighttime.