A kind of preparation method of methyl p-methoxycinnamate

Abstract

The invention discloses a preparation method of methyl p-methoxycinnamate. Add methyl acetate, methanol, sodium methoxide and cyclic ether into the condensation reactor, and react at reflux temperature; then add p-methoxybenzaldehyde, and circulate the reaction solution through the reaction bed filled with catalyst, After the addition of benzaldehyde is completed, the reaction is continued by reflux and insulation, and the water generated by the reaction is separated and removed. By adding methanol and cyclic ether and removing the generated water, the amount of catalyst used can be reduced to a very low level. By circulating the reaction solution through the reaction bed equipped with metal oxide catalysts, the 3 generated in the reaction process ‑Methoxy‑3‑methyl p-methoxyphenylpropionate is converted into methyl p-methoxy cinnamate in time, which improves the purity and yield of the product, and at the same time does not require acid-base neutralization process, and does not generate excess waste water and Compared with traditional processes, other solid wastes have equivalent or higher conversion rates and selectivity, lower production costs, and are more environmentally friendly.

Description

technical field [0001] The invention belongs to the field of chemical industry, and relates to a preparation method of p-methoxycinnamate, in particular to a preparation method of methyl p-methoxycinnamate. Background technique [0002] P-methoxycinnamate, especially the higher ester of p-methoxycinnamate is an excellent ultraviolet absorber and can be used as a chemical sunscreen. Methyl p-methoxycinnamate is the raw material for the synthesis of higher esters of p-methoxycinnamate, and it also has important applications in the pharmaceutical field. [0003] At present, the preparation method of the mainstream p-methoxycinnamate in the industry is that p-methoxybenzaldehyde is prepared by the Claisen-Schmidt reaction route as raw material: [0004] P-methoxybenzaldehyde and methyl acetate are reacted in a conventional hydrocarbon solvent with a strong base such as sodium methoxide as a catalyst, and the resulting mixture is reacted at 40-65°C for 2-6 hours, and the corresp...

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Problems solved by technology

[0011] In order to improve the yield and purity of methyl p-methoxycinnamate, the method adopted in patent JP617236 is to separate 3-methoxy-3-methyl p-methoxyphenylpropionate, which will reduce the reaction yield , the method adopted by the patent JP283462 is to treat the reaction solution containing 3-methoxy-3-p-methoxyphenyl propionate methyl ester with liquid acid after the reaction, and 3-methoxy-3-p-methoxy Methyl phenylpropionate is converted into methyl p-methoxycinnamate. Although this method improves the reaction yield, it involves multiple acid-base neutralization processes and increases the amount of saline wastewater. The method adopted in patent EP0165521 is to After the reaction, the reaction solution containing 3-methoxyl-3-p-methoxyphenylpropionic acid methyl ester is treated with alkaline hydroxide, and 3-methoxyl-3-p-methoxyphenylpropionic acid methyl Ester is converted to methyl p-methoxycinnamate, which has the same problem as the patent JP283462

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