Theoretical study of nucleophilic halogenalkylation of propylene oxide with halogenmethane and dihalogenmethane anion

摘要

The nucleophilic halogenalkylation reactions of propylene oxide with halogenmethane anion (CH2X-) and dihalogenmethane anion (CHX$^{-}_{2}$) (X = F, Cl) in the gas phase and in the Et2O solvent are studied using the B3LYP method and the SCIPCM model for simulating solution effects. Our calculations predict the same reaction path for following reactions: (1) (X = F, Cl) and (2) (X = F) in the two phases, but there is a little difference in the relative energy of IM1(2Cl) in the gas phase and in the Et2O solvent for reaction (2) (X = Cl). All the four reactions proceed in two steps. Reactions (1) and (2) are predicted to be exothermic and thermodynamically favourable in both the gas phase and the Et2O solvent. The overall barrier energies for reaction (1) (X = F), reaction (1) (X = Cl), reaction (2) (X = F), and reaction (2) (X = Cl) are predicted to be 2.74 and 4.08 kcal mol-1, 3.35 and 5.20 kcal mol-1, 4.67 and 6.05 kcal mol-1, and 5.33 and 8.23 kcal mol-1 in the gas phase and in the Et2O solvent, respectively. The accurate calculation of results for the model systems would be useful for experimental researchers working in this field.