Atmospheric oxidation of 2-fluoropropene (CH3CFCH2) with Cl atom and aerial degradation of its product radicals by computational study

Abstract

A detailed atmospheric degradation study of the 2-fluoropropene (2-FP) molecule initiated by various oxidants is essential as it is released due to various applications. So, in this manuscript, we have examined the Cl-atom initiated H-abstractions from 2-FP and Cl-atom addition to α- and β-carbons of 2-FP using the MP2/6-31+G(d,p) level of theory. Here, we have explored all the reaction species along with intermediates and transition states of the 2-FP + Cl reaction on the potential energy surface (PES). Enthalpy and Gibb's free energy changes of all reaction channels are determined to understand their nature and feasibility. PES and thermo-chemistry results indicate that all the reaction channels are exothermic and feasible but H-abstraction from the α-carbon of 2-FP by Cl-atom is thermodynamically more dominant. On the other hand, kinetic and subsequent branching ratio calculation results show that Cl-atom additions to α- and β-carbons of 2-FP are kinetically more dominant than H-abstraction channels. Our calculated overall rate constant at 298 K and 1 atm is found to be 1.07 × 10⁻¹⁰ cm³ molecule⁻¹ s⁻¹, which is in good agreement with the experimental overall rate. The atmospheric lifetime of 2-FP is found to be 10.8 days, which signifies the very short lifetime and negligible effect on the global warming potential. Moreover, aerial degradation of Cl-atom addition product radicals in the presence of NO radicals is further carried out at the same level of theory. From this investigation, we have obtained 2-chloroacetyl fluoride (CF(O)CH₂Cl), carbonic chloride fluoride (CFCl(O)) and formaldehyde (HCHO) as more stable end products.