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 kOH = 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.