Computational studies on the thermal decomposition of the CH2FOCHFO radical

Theoretical studies have been carried out on the kinetics and thermochemistry of the thermal decomposition of the CH₂FOCHFO radical formed during the photo-oxidation of CH₂FOCH₂F (HFE-152E) using the dual-level method of obtaining the optimised structure at DFT(M06-2X)/6-311++G(d,p) followed by a single-point energy calculation at the G3 level of theory. The rate constant for different reaction channels involved during the decomposition processes of CH₂FOCHFO is evaluated at 298 K and 1 atm using canonical transition-state theory. The results point out that the C–H bond scission is the dominant path involving an energy barrier of 9.5 kcal mol^?1 determined at the G3 level of theory. A potential energy diagram is constructed and the results are compared with the data available from the literature for a structurally similar molecule.     

Characterization by NMR of reactants and products of hydrofluoroether isomers,CF3(CF2)3OCH3 and (CF3)2C(F)CF2OCH3, reacting with isopropyl alcohol

The 3M Company product Novec? 71IPA DL, a mixture of methoxyperfluorobutane, methoxyperfluoroisobutane and 4.5 wt.% isopropyl alcohol, has been found to be very stable at ambient temperature, producing fluoride at the rate of ~1 ppm/year. Our earlier kinetic and theoretical studies have identified the reaction mechanism. This paper identifies the ¹H and ¹⁹F NMR chemical shifts, multiplicities, and coupling constants of reactants and the major products that result from aging the mixture in sealed Pyrex NMR tubes for periods up to 1.8 years at temperatures from 26 °C to 102 °C. Chemical shifts and coupling constants of fluorine and hydrogen atoms on the hydrofluoroethers and isopropyl alcohol are traced through the reactions to their values in the products – esters, isopropylmethyl ether, and HF. These spectral positions, multiplicities, and coupling constants are presented in table format and as figures to clarify the transformations observed as the samples age. Copyright © 2013 John Wiley & Sons, Ltd.     

Kinetic parameters for the reaction of hydroxyl radical with CH3OCH2F (HFE‐161) in the temperature range of 200–400 K: Transition state theory and Ab initio calculations

Rate coefficients for the reaction of the hydroxyl radical with CH₃OCH₂F (HFE‐161) were computed using transition state theory coupled with ab initio methods, viz., MP2, G3MP2, and G3B3 theories in the temperature range of 200–400 K. Structures of the reactants and transition states (TSs) were optimized at MP2(FULL) and B3LYP level of theories with 6‐31G* and 6‐311++G** basis sets. The potential energy surface was scanned at both the level of theories. Five different TSs were identified for each rotamer. Calculations of Intrinsic reaction coordinates were performed to confirm the existence of all the TSs. The kinetic parameters due to all different TSs are reported in this article. The rate coefficients for the title reaction were computed to be k = (9 ± 1.08) × 10^?13 exp [?(1,713 ± 33)/T] cm³ molecule^?1 s^?1 at MP2, k = (7.36 ± 0.42) × 10^?13 exp [?(198 ± 16)/T] cm³ molecule^?1 s^?1 at G3MP2 and k = (5.36 ± 1.57) × 10^?13 exp [?(412 ± 81)/T] cm³ molecule^?1 s^?1 at G3B3 theories. The atmospheric lifetimes of CH₃OCH₂F at MP2, G3MP2, and G3B3 level of theories were estimated to be 20, 0.1, and 0.3 years, respectively. © 2011 Wiley Periodicals, Inc. Int J Quantum Chem, 2012