Method for preparing p-bromoanisole by oxidative bromination method

Abstract

The invention provides a method for preparing bromoanisole by an oxidative bromination method, which comprises the following steps of: oxidizing hydrobromic acid by anisole under the action of a catalyst and hydrogen peroxide, and brominating the anisole to obtain p-bromoanisole. The catalyst is a nitrogen-containing carbon material immobilized phosphotungstic acid catalyst, is simple to prepare, has relatively high activity and selectivity, is good in stability, can be repeatedly used for multiple times, can be used for catalyzing highly selective oxidative bromination of anisole to prepare p-bromoanisole, and has a very good industrial application prospect.

Description

technical field [0001] The invention relates to a method for preparing bromoanisole by an oxidative bromination method, in particular to a method for preparing p-bromoanisole by catalytic oxidation of brominated anisole. Background technique [0002] p-Bromoanisole is an important organic synthesis and pharmaceutical intermediate, which is widely used in fragrances, dyes and other industries. Obtain anisole, then further react with bromine to obtain p-bromoanisole; or take anisole as a raw material, carry out bromination reaction with bromine in glacial acetic acid, but bromine is a strong stimulus and corrosion It is very dangerous to handle, and the temperature of the reaction system reaches 140-150 ° C, the yield of p-bromoanisole is only about 60%, not only the product and yield are economical, but also the high-temperature reaction will increase the ortho-brominated product. . [0003] Yin Haichuan et al. improved the reaction route for the preparation of p-bromoaniso...

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Problems solved by technology

[0002] p-bromoanisole is an important organic synthesis and pharmaceutical intermediate, widely used in spices, dyes and other industries, its common preparation method is to use p-bromophenol as raw material, react with dimethyl sulfate in alkaline solution to obtain anisole, and further react with bromine to obtain p-bromoanisole; or use anisole as a raw material to carry out bromination reaction with bromine in glacial acetic acid, but bromine is a strong irritant and corrosive It is very dangerous to handle, and the temperature of the reaction system reaches 140-150 °C, and the yield of p-bromoanisole is only about 60%. Not only the product and yield are low in economy, but also the high temperature reaction will also increase the ortho brominated product

[0003] Yin Haichuan and others improved the reaction route for preparing p-bromoanisole from p-bromophenol (Yunnan Metallurgy. 2000, 6:41-42), using phenol as raw material and adding bromine to carbon disulfide at low temperature to prepare bromophenol Further substitution reaction with dimethyl sulfate occurs, and the yield of p-bromoanisole is increased to 87.5%, but the technical process is lengthy and complicated, and it is inevitable to use strong irritating corrosive substance bromine

People such as Shao Yan take anisole as raw material, utilize sodium bromide to provide bromine source, oxygen is oxygenant, the catalytic oxidation bromination reaction of anisole carried out in glacial acetic acid prepares p-bromoanisole (Guangdong Chemical Industry.2006.8: 12-13), this method avoids the environmental pollution caused by the use of bromine, strong acid and strong oxidant after the reaction, but the reaction temperature reaches 120°C, and the mixing of oxygen and nitric oxide at high temperature will have a great safety hazard, which is not conducive to industrial mass production

Guodong Zhao et al reported using FeBr 2 or CeBr 3 In-situ generation of brominated active substances with hydrogen peroxide and reaction with anisole, the yield of the product p-bromoanisole increased to 79% (ACS Sustainable Chem.Eng.2021,9:6118-6125), the reaction conditions of this method are mild , while avoiding the environmental pollution and danger caused by the direct use of bromine; Yizhi Yuan et al. utilize dimethyl sulfoxide as an oxidant and hydrobromic acid p-anisole to carry out efficient palladium-catalyzed oxidative bromination to synthesize p-bromoanisole ( Chin.J.Chem.2020,38:1245-1251), this method has developed a kind of mild oxidant dimethyl sulfoxide, and the yield of p-bromoanisole is improved to 87%, but noble metal palladium is expensive, not Suitable for industrial application, and the reaction time is as long as 36 hours, further increasing the economic cost

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