Theoretical investigation on kinetics and thermochemistry of reaction of CHF₂CF₂OCH₂CF₃ with OH radicals and global warming potentials

Abstract

Theoretical investigation has been carried out on the mechanism, kinetics and thermochemistry of the gas-phase reactions between CHF₂CF₂OCH₂CF₃ and OH radical using a new hybrid density functional M06-2X/6-31+G(d,p) and G2(MP2)//M06-2X/6-31+G(d,p) methods. The most stable conformer of CHF₂CF₂OCH₂CF₃ is considered in our study and the possible H-abstraction reaction channels are identified. Each reaction channel shows an indirect H-abstraction reaction mechanism via the formation of pre-reactive complex. The rate coefficients are determined for the first time over a wide range of temperature 250–1000 K. At 298 K, the calculated total rate coefficient of k_OH = 1.01×10⁻¹⁴ cm³ molecule⁻¹ s⁻¹ is in good agreement with the experimental results. The heats of formation for CHF₂CF₂OCH₂CF₃ and CF₂CF₂OCH₂CF₃ and CHF₂CF₂OCHCF₃ radicals are estimated to be -1739.25, -1512.93 and -1523.94 kJ mol⁻¹, respectively. The bond dissociation energies of the two C-H bonds are C(-H)F₂CF₂OCH₂CF₃: 423.34 kJ mol⁻¹ and CHF₂CF₂OC(-H)HCF₃: 411.87 kJ mol⁻¹. The atmospheric lifetime of CHF₂CF₂OCH₂CF₃ is estimated to be around 4.5 years and the 100-year time horizon global warming potentials of CHF₂CF₂OCH₂CF₃ relative to CO₂ is estimated to be 601.

Keywords:

• CHF₂CF₂OCH₂CF₃
• OH radical
• M06-2X
• rate coefficient
• atmospheric lifetime
• global warming potentials

Additional information

Funding

AKC thanks UGC, India for financial grant (No.540/21/CAS/2013(SAP-I)) and Computer Centre, NEHU for providing computing facilities. ML thanks DST, India for a research fellowship.