Abstract The molecular structures of six benzene derivatives, such as phenol, anisole, aniline, phenolate, 4-hydroxybenzaldehyde and 4-methoxybenzaldehyde, have been optimized by using B3LYP/DFT method and 6-311+G** basis set. By comparing the bond lengths and Pi-electron population numbers of these compounds, an order of abilities to activate benzene was obtained as follows: -OH32-. The free energies of rate determined step of F-C methylation reactions of phenol, anisole, aniline and phenolate were also calculated, the resuls showed that the reaction activity order is: phenol< anisole< aniline< phenoxy anion. The conclusion of this paper is: the ability to activate benzene of hydroxyl is slight weaker than that of methoxyl, but the ability to activate benzene of oxygen anion is much stronger than those of hydroxyl and methoxyl.
