Chlorine-Atom-Initiated Reaction Mechanisms, Kinetics, and Global Warming Potentials of CF3(CF2)2CH═CH2 (HFO-1447fz) and Interpreting the Fate of Its Product Radicals

Abstract

The oxidation of 3,3,4,4,5,5,5-heptafluoro-1-pentene (CF₃(CF₂)₂CH═CH₂, HFO-1447fz) initiated by Cl atoms has been carried out to understand the atmospheric impact of this compound. The initial molecular electrostatic potential and Fukui function calculations at the MP2/6-31+G(d,p) method indicate that the α- and β-C atoms of CF₃(CF₂)₂CH═CH₂ are the electron-deficient region and a suitable site of nucleophilic attack. Further, reaction energies, thermodynamic parameters, and kinetics calculated at the MP2/6-31+G(d,p) method are refined using the CCSD(T)//MP2/6-31+G(d,p) and CCSD(T)/6-311++G(d,p)//MP2/6-31+G(d,p) methods. The energy profile diagram and thermodynamic result indicate that the predominant reaction pathway is the Cl-atom addition pathways to the α- and β-C atoms of CF₃(CF₂)₂CH═CH₂, compared to the H-abstraction pathways of CF₃(CF₂)₂CH═CH₂ by Cl atoms. The overall rate coefficients for the CF₃(CF₂)₂CH═CH₂ + Cl reaction are calculated over the temperature range of 200–400 K. The first-time-calculated overall rate coefficient at 298.15 K is found to be 1.39 × 10^–10 cm³ molecule^–1 s^–1, at the CCSD(T)/6-311++G(d,p)//MP2/6-31+G(d,p) method. We also reported the atmospheric lifetime and global warming potential (GWP) of the title reaction for the first time. Furthermore, we have explored the degradation reaction pathways of the Cl-atom addition product radicals in the presence of O₂/NO. It suggests the emergence of some small and stable end products such as HCHO, HCOCl, FCFO, and CF₃(CF₂)₂CHO. We hope this investigation will be helpful in understanding the atmospheric fate and environmental impact of this titled molecule.