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

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 BrCHCHCHCl → CHCHCHCl + HBr at 400-1000 K were = 6.1 × 10 exp(-57.2 kcal mol/RT) s and = [BrCHCHCHCl] 1.45 × 10 (/1000 K) exp(-55.9 kcal mol/RT) cm molecule s. A value of -26.3 ± 1.0 kcal mol for the standard enthalpy of formation of 1-bromo-3-chloropropane at 298 K was derived.