Temperature dependence of rate constants for the H(D) + CH4 reaction in gas and aqueous phase: deformed Transition-State Theory study including quantum tunneling and diffusion effects

Abstract

In recent years, the understanding and control of mechanisms involving radical attacks to hydrocarbons have been object of investigation in several fields, especially in combustion reactions and energy resource technology. The H(D) + CH4 ⟶ CH3 + H2(HD) reactions are known as prototypical reactions of hydrocarbons and have been extensively investigated both experimentally and theoretically in the gas-phase. Here, the reaction rate constants for the hydrogen abstraction of methane by atomic hydrogen (and deuterium) in the gas phase have been validated by employing the deformed Transition-State Theory ($$ d $$-TST): The results motivated the use of Collins-Kimball approaches to provide kinetics data in the aqueous phase. The $$ d $$-TST has been found to be accurate for absolute values and temperature dependence of the reaction rate constant in the gas phase, especially for what concerns the excellent agreement with experimental data for the variant isotopic when compared with previous formulations. For the first time, theoretical rate constants in aqueous solution for the title reaction are presented reproducing the experimental data at 288.15 K.