The preparation method of 2-bromo-1,3-dimethoxybenzene

Abstract

The invention discloses a method for preparing 2-bromo-1,3-dimethoxybenzene, which comprises the following steps: using tetrahydrofuran as a solvent, adding iso-xylylene ether, stirring and dissolving, then cooling to 5-10° C., slowly dripping Add n-butyllithium, the internal temperature is controlled at 5-10°C and the dropwise addition is completed, then the internal temperature is restored to 20-25°C, matured for 1-2h to obtain Intermediate I; then use a dry ice-acetone bath to reduce the temperature to -60 After ℃~-70℃, slowly add the 1,2-dibromotetrafluoroethane solution of tetrahydrofuran dropwise, after the dropwise addition, return the internal temperature to 20~25℃, and mature for 2~3h; Using an ice-water bath, the temperature was lowered to 0-5 °C, and 1N dilute hydrochloric acid was added dropwise to quench the reaction; ethyl acetate was then added for extraction and separation, and the combined organic phases were washed with tap water, saturated brine, and dried over magnesium sulfate. Reaction after-treatment such as concentration under reduced pressure obtains a crude product of yellowish white needle-like crystals; the crude product is recrystallized from n-hexane to obtain high-purity 2-bromo-1,3-dimethoxybenzene, and the GC purity can reach 99.9% above.

Description

technical field [0001] The invention relates to a preparation method for synthesizing high-purity 2-bromo-1,3-dimethoxybenzene, and belongs to the technical field of synthesis for the development and application of important organic material synthesis intermediates and pharmaceutical intermediates. Background technique [0002] 2-Bromo-1,3-dimethoxybenzene is an important fine organic chemical product and an intermediate in the organic synthesis of pharmaceuticals. New drug synthesis and development research. With the continuous development of economy and science and technology, the market demand of 2-bromo-1,3-dimethoxybenzene will increase year by year. Therefore, it is very important to develop a method for synthesizing high-purity 2-bromo-1,3-dimethoxybenzene and realizing industrialization. At present, the domestic research reports on the synthesis of 2-bromo-1,3-dimethoxybenzene are mostly prepared by using the raw material iso-xylylene ether and reacting with bromin...

AI Technical Summary

Problems solved by technology

At present, domestic research reports on the synthesis of 2-bromo-1,3-dimethoxybenzene, most of which are prepared by reacting m-xylylene dimethyl ether with brominating reagents such as bromine, NBS, hydrobromic acid, etc. However, the reaction selectivity is poor, the side reactions are many, the purification is difficult, and the yield is very low. In addition, the raw material bromination reagent and the waste generated by the reaction have serious pollution to the environment and are not suitable for green industrial production.

Images