Hydrolysis of Formyl Fluoride Catalyzed by Sulfuric Acid and Formic Acid in the Atmosphere

Formyl fluoride (HFCO) is an important atmospheric molecule, and its reaction with the OH radical is an important pathway when degradation of HFCO is considered in earth's troposphere. Here, we study the hydrolysis of formyl fluoride (HFCO + H 2 O) with sulfuric acid (H 2 SO 4 ) and formic acid (HCOOH) acting as catalysts by utilizing M06-2X, CCSD(T)-F12a, and conventional transitional state theory with Eckart tunneling to explore the atmospheric impact of the above-said hydrolysis reactions. Our calculated results show that H 2 SO 4 has a remarkably catalytic role in the gas-phase hydrolysis of HFCO, as the energy barriers of the HFCO + H 2 O reaction are reduced from 39.22 and 41.19 to 0.26 and -0.63 kcal/mol with respect to the separate reactants, respectively. In addition, we also find that H 2 SO 4 can significantly accelerate the decomposition of FCH(OH) 2 into hydrogen fluoride (HF) and HCOOH. This is because while the barrier height for the unimolecular decomposition of FCH(OH) 2 into HF and HCOOH is 31.63 kcal/mol, the barrier height for the FCH(OH) 2 + H 2 SO 4 reaction is predicted to be -5.99 kcal/mol with respect to separate reactants. Nevertheless, the comparative relative rate analysis shows that the reaction between HFCO and the OH radical is still the most dominant pathway when the tropospheric degradation of HFCO is taken into account and that the gas-phase hydrolysis of HFCO may only occur with the help of H 2 SO 4 when the atmospheric concentration of OH is about 10 1 molecules cm -3 or less. Having an understanding from the present study that the gas-phase hydrolysis of HFCO in the presence of H 2 SO 4 has very limited role possibly in the absence of sunlight, we also prefer here to emphasize that the HFCO + H 2 O + H 2 SO 4 reaction may occur on the surface of secondary organic aerosols for the formation of HCOOH.