Decomposition and Kinetics of CH2(OH)C(O•)(CH3)CH2Cl Radical in the Atmosphere: A Quantum Mechanical Study
We have presented the quantum mechanical calculations of the decomposition pathways of 1, 2-hydroxy alkoxy radical i.e. CH2(OH)C(O•)(CH3)CH2Cl radical. This radical species is formed from the successive reactions with O2 molecule and NOx or HO2 radicals with the most stable primary oxidation product of 3-chloro-2-methyl-1-propene and OH radical reaction. Geometry optimization and frequency calculations of all the stable species including transition states in the three possible C-C bond scission pathways (i.e. C-CH3, C-CH2Cl and C-CH2OH) of CH2(OH)C(O•)(CH3)CH2Cl radical are performed at M06-2X/6-31+G(d,p) level of theory. We have further performed single point energy calculations of all the optimized species at the higher level of CCSD(T) method along with cc-pVTZ triple-zeta basis set. The rate constants for the various decomposition reactions are evaluated using Canonical Transition State Theory (CTST) within the temperature range of 250−400 K. Rate constants for C–C bond scissions of C-CH3, C-CH2Cl and C-CH2OH of the 1, 2-hydroxy alkoxy radical are found to be 4.17 × 101, 1.59 × 103 and 1.38 × 109 s-1 respectively at 298 K and 1 atm. The energetic and kinetics results suggest that C–CH2OH bond scission of titled radical is more dominant than other decomposition channels.
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