Thermal decomposition of CF 3 CFClO radical – A computational study

A theoretical study on the decomposition pathways of haloalkoxy radical formed from 2-chloro-1,1,1,2-tetrafluoroethane has been reported. Structures of all the reactants, products and transition states involved in the decomposition pathways have been optimized and characterized at MP2(full)/6-31G(d,p) level of theory. Single point energy calculations have been performed using MP4, QCISD(T) and CCSD(T) levels of theory. Critical energy barriers have been calculated for C-C bond scission and Cl elimination, the two prominent decomposition channels considered in the present investigation, and found to be 8.4 and 1.5 kcal mol -1 respectively. Results show that Cl elimination is the dominant path involving a lower barrier height. Using transition state theory, rate constants for the decomposition pathways, viz., Cl-elimination and C-C bond scission, calculated at 298 K and 1 atm pressure are found to be 4.6×10 5 and 5.1×10 4 s -1 , respectively. The existence of transition states on the corresponding potential energy surface has been ascertained by performing Intrinsic Reaction Coordinate calculations.