The Theory Study On Synthesis Of 4-methoxyphenol And Its Experiments

It is important field to use density function theory (DFT) to study organic reaction system in organic chemistry. In this article, the basic of DFT was introduced on brief. The development of the DFT studied on organic chemistry was summarized. On DFT, the reality system that the synthesis of 4-methoxyphenol with hydroquinone and methlation regent was discussed in detail.4-methoxyphenol is an important raw material that widely utilized in pharmacy and organic synthesis. Beaause of its high produce consume, and no study on the merchism of the reaction, the utilization of 4-methoxphenol is limited. In this article, DFT/B3LYP calculations at 6-31G(d,p) basis set level were carried out for optimized the reactant and transition state and the product's structure of the reaction that hydroquinone reacted with dimethyl sulfate or dimethyl carbonate. Then the charge density and Mulliken overlap population were calculated under PCM model. The reaction mechanism was confirmed.The transition state was optimized by TS method, then caculated the frequency of the transition state. Finally analyzed the transition state by IRC. According to the calculation result, discovered that when hydroquinone transited into 4-methoxyphenol, the charge density of oxygen reduced, it is advantage to main reaction. But when the sodium hydroxide overmuch, hydroquinone transited into benzene-1,4-diolate, it is benefit to assistant reaction. In other hand, the absorb energy of assistant reaction is higher than the main reaction, so high temperature is advantage to assistant reaction. But low temperature can't satisfied the absorb energy of the main reaction. Finally optimized the space construction of dimethyl carbonate, calculated its overlap population, discovered the reason that dimethyl carbonate is difficult to as methylation regent. Discussed the mechanism of the reaction the dimethyl reacts with phenol and amine nucleophilic regent in the presence of the Lewis acid. Discussed the influence of the regent on the reaction.According to the calculation result, choose the adapt reaction condition to experiment. Considered the influence of the reaction temperature, reaction time, dosage of catalyze, and other reaction condition. Controlled the rate of 4-methoxyphenol and 1,4-Dimethoxybenzene is 1:0.16. The harvest rat of the dimethyl carbonate reaction with hydroquinone in the presence of Lewis acid is 66.18%.