Quantum chemical and kinetic study of the CCl2 + HCl → CHCl3 insertion reaction

Publication date: Available online 4 February 2020Source: Computational and Theoretical ChemistryAuthor(s): Nicolás D. Gómez, M. Laura Azcárate, Jorge Codnia, Carlos J. CobosAbstractThe CCl2 + HCl → CHCl3 (1) insertion reaction has been investigated by ab initio molecular orbital and kinetic calculations. The geometries of reactants, products and transition state were optimized with a large number of density functional theory (DFT) formulations combined with the 6-311++G(3df,3pd) basis set. The reaction barriers calculated with G4(MP2)//DFT and G4//DFT theories of 1.16 ± 0.27 and 0.61 ± 0.26 kcal mol-1 are consistent with the barrier height of ΔE0# = 1.54 ± 0.30 kcal mol-1 estimated from the room temperature experimental rate constant. Calculated enthalpies of reaction of -53.97 ± 0.09 (G4(MP2)//DFT), -55.27 ± 0.09 (G4//DFT) and -56.52 ± 3.90 kcal mol-1 (DFT) agree well with experimental values. The obtained rate constants over the 300 - 2000 K temperature range at the high and low pressure limit can be expressed as k1,∞(G4(MP2)//DFT) = (4.8 ± 1.8) x 10-14 (T/300 K)2.12±0.19 and k1,∞(G4//DFT) = (9.8 ± 3.4) x 10-14 (T/300 K)1.77±0.16 in cm3 molecule-1 s-1, and k1,0 = [HCl] 3.40 x 10-27 (T/300 K)-6.57 exp(-2218 K/T) cm3 molecule-1 s-1. Falloff curves for the intermediate pressure range obtained for the reactions (1, -1) with these rate constants and a derived central broadening factor of Fcent = 0.16 + 0.84 exp(-T/331 K) + exp(-7860 K/T) were compared with r...

Source: Computational and Theoretical Chemistry - February 5, 2020 Category: Chemistry Source Type: research