Theoretical study on the fluorination of benzene with N-Fluoropyridinium salts in acetonitrile solution

Abstract

The prominent roles of organofluorine compounds in various fields have aroused considerable interest in the development of new methods for carbon-fluorine bond formation. Electrophilic fluorination receives much attention. Density functional theory (DFT) was used to theoretically explore the fluorination activity of 12 N-Fluoropyridinium salts on the substrate of benzene in acetonitrile solution. Geometry optimizations and frequency calculations of the reactants, transition states, and products were performed at B3LYP/6-311G(d,p) level for the 12 fluorination reaction channels. Based on the optimized structure, all the stationary points have been corrected by the single point energy at a high-level of M06-2x/6-311++G (d,p). Four substituents were considered in this paper, they are nitro-, cyano-, chloro-, methoxy-, respectively. Three substituted sites (ortho-, meso-, para-) were also concluded. Based on the obtained potential energy surfaces information and analysis of substituent effect, the fluorination reaction channel of oNO2NFpyr is most efficient due to the lowest reaction energy barrier; therefore, oNO2NFpyr is a promising optimum fluorinating reagent among the studied 12 N-Fluoropyridinium salts.