Quantum-Chemical Kinetic Study of the Unimolecular Decomposition Reactions of 1-Bromo-3-Chloropropane

Abstract

The pressure and temperature dependence of the thermal decomposition of 1-bromo-3-chloropropane has been theoretically investigated. The reaction takes place majorly through the elimination of HBr. Molecular properties of 1-bromo-3-chloropropane and transition states were derived from MN15/6-311++G­(3df,3pd) and G4 quantum-chemical calculations. The resulting rate constants obtained from the unimolecular reaction rate theory for the high- and low-pressure limits of reaction BrCH2CH2CH2Cl → CH2CHCH2Cl + HBr at 400–1000 K were k ∞ = 6.1 × 1013 exp­(−57.2 kcal mol–1/RT) s–1 and k 0 = [BrCH2CH2CH2Cl] 1.45 × 10–1 (T/1000 K)−7.9 exp­(−55.9 kcal mol–1/RT) cm3 molecule–1 s–1. A value of −26.3 ± 1.0 kcal mol–1 for the standard enthalpy of formation of 1-bromo-3-chloropropane at 298 K was derived.