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

Abstract

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 + H2O) with sulfuric acid (H2SO4) 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 H2SO4 has a remarkably catalytic role in the gas-phase hydrolysis of HFCO, as the energy barriers of the HFCO + H2O 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 H2SO4 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 + H2SO4 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 H2SO4 when the atmospheric concentration of OH is about 101 molecules cm–3 or less. Having an understanding from the present study that the gas-phase hydrolysis of HFCO in the presence of H2SO4 has very limited role possibly in the absence of sunlight, we also prefer here to emphasize that the HFCO + H2O + H2SO4 reaction may occur on the surface of secondary organic aerosols for the formation of HCOOH.

New Reactions for the Formation of Organic Nitrate in the Atmosphere

“…The detailed expression of the trimolecules is provided by the reaction pathway HNO 3 •••H 2 O + HCHO as an example in the Supporting Information, and this reaction is similar to our previous studies in the HFCO + H 2 O + H 2 SO 4 72 and HCHO + H 2 SO 4 + HCOOH 51 reactions.…”

Reactions of Criegee Intermediates are Enhanced by Hydrogen‐Atom Relay Through Molecular Design

“…Plentiful computational studies have also shown that DHAT reactions result in a catalytic effect. Examples include: (i) gas‐phase hydrolysis of HFCO is catalyzed by H 2 SO 4 ; (ii) decomposition of CF 3 OH is catalyzed by formic acid; (iii) SO 3 hydration is catalyzed by oxalic acid; (iv) SO 3 +NH 3 reaction is catalyzed by NH 3 , etc. Furthermore, double H‐atom exchange reactions of HO 2 +HX (X=F, Cl, Br, I) have also been predicted computationally …”

An unexpected feasible route for the formation of organosulfates by the gas phase reaction of sulfuric acid with acetaldehyde catalyzed by dimethylamine in the atmosphere

“…The reliability of the M06-2X functional and its wide application have been demonstrated in previous studies on the atmospheric reactions of sulfuric acid and sulfuric acid molecular clusters. 48–53 The calculated results of the corresponding frequencies of reactants, complexes, transition states, and products using M06-2X/MG3S suggest that all stable structures have positive frequencies, while the transition state has only one imaginary frequency. The stability of the density functional theory method has been tested by using the keyword (stable = opt).…”

“…The CH 3 CHO + H 2 SO 4 … (CH 3 ) 2 NH reaction occurs in one elementary step as depicted in Figure 1, which is similar to the hydrolysis of acetaldehyde catalyzed by sulfuric acid, as well as the reaction of formaldehyde with sulfuric acid catalyzed by formic acid and others. 34,36,50,51,53,81,82,83 It can be seen that when the H 2 SO 4 … (CH 3 ) 2 NH complex and CH 3 CHO act as reactants, the reaction occurs via the formation of prereaction complexes and then undergoes a unimolecular isomerization through these corresponding transition states responsible for the formation of post-reaction complex. In the CH 3 CHO + H 2 SO 4 … (CH 3 ) 2 NH reaction, there is a concerted reaction mechanism that the hydrogen atom of the OH group in sulfuric acid is transferred to the oxygen atom of the carbonyl group in CH 3 CHO by the amino group in dimethylamine, and simultaneously the oxygen atom of the S=O group in sulfuric acid is added to the carbon atom in CH 3 CHO, where dimethylamine is acted as a catalyst; this leads to the formation of the most stable post-reaction complex (CP1), which is a nucleation precursor of secondary organic aerosols.…”