Theoretical Study on Gas Phase Reactions of OH Hydrogen-Abstraction from Formyl Fluoride with Different Catalysts

Abstract

The mechanisms and kinetics of the gas phase reactions that the hydrogen atom in formyl fluoride (FCHO) abstracted by OH in the presence of water, formic acid (FA), or sulfuric acid (SA) are theoretically investigated at the CCSD(T)/6-311++G(3df, 3pd)//M06-2X/6-311++G(3df, 3pd) level of theory. The calculated results show that the barriers of the transition states involving catalysts are lowered to −2.89, −6.25, and −7.76 kcal/mol from 3.64 kcal/mol with respect to the separate reactants, respectively, which reflects that those catalysts play an important role in reducing the barrier of the hydrogen abstraction reaction of FCHO with OH. Additionally, using conventional transition state theory with Eckart tunneling correction, the kinetic data demonstrate that the entrance channel X⋯FCHO+OH (X=H2O, FA, or SA) is significantly more favorable than the pathway X⋯OH+FCHO. Moreover, the rate constants of the reactions of FCHO with OH radical with H2O, FA, or SA introduced are computed to be smaller than that of the naked OH+FCHO reaction because the concentration of the formed X⋯FCHO or X⋯OH complex is quite low in the atmosphere.