CuI/BtH催化苯硫酚与对甲氧基溴苯C-S偶联合成(4-甲氧基)(苯基)硫醚反应机理理论研究

Abstract

The mechanism of CuI/BtH catalyzed C-S coupling reaction of benzenethiol and 1-bromo-4- methoxybenzene to synthesize (4-methoxyphenyl)(phenyl)sulfane has been investigated by density functional theory (DFT). The geometries of reactants, intermediates, transition states, and products were optimized in both gaseous phase and solvent N , N -dimethyl formamide (DMF) at the B3LYP/6-31+G(d) level. The single point energies and zero point energy correction were calculated for the optimized configuration of each compound at B3LYP/6-311+ +G(d,p) level. Vibration analysis, energy calculation and IRC calculation proved the authenticities of the intermediates and the transition states. Atoms in molecules (AIM) and nature bond orbital (NBO) theories were used to discuss the bond nature and orbital interactions at the same of optimization calculation level. In CuI catalytic mechanism, there is one pathway, the rate-determining step activation energy of which is 180.49 kJ/mol in solution. In CuI/BtH catalytic mechanism, there are two possible pathways: I A is the optimal pathway and the activation energy of rate-determining step is 101.77 kJ/mol; the activation energy of rate-determining step in I B is 143.78 kJ/mol (sol). Since the ligand 1H-benzo[ d ][1,2,3]triazole (BTH) can reduce the activation energy of rate-determining step and the dissociation energy of catalyst, meanwhile, it is favorable for the separation of products and catalyst, which is in accordance with experimental results.