Synthesis method and device of 2,3,5-trimethylhydroquinone

Abstract

The invention discloses a synthesis method and device of 2,3,5-trimethylhydroquinone. According to the synthesis method for 2,3,5-trimethylhydroquinone, 2,3,5-trimethylbenzoquinone (TMBQ) and an alcohol-aromatic hydrocarbon or alcohol-alkane mixed solvent system are mixed, then a reaction solution is fully mixed with hydrogen through a hydrogen absorber, then the mixture enters a fixed bed filledwith a noble metal catalyst to complete a hydrogenation reaction, and 2,3,5-trimethylhydroquinone (TMHQ) is obtained. According to the technical scheme provided by the invention, the reaction selectivity is improved, the side reaction is effectively inhibited, the impurity content of the product is reduced, the purity of 2,3,5-trimethylhydroquinone (TMHQ) is improved, the production process is simplified, the emission of three wastes is reduced, and the method has good environmental protection benefits.

Description

technical field [0001] The invention relates to the field of fine organic chemical synthesis, in particular to a synthesis method and device for 2,3,5-trimethylhydroquinone. Background technique [0002] 2,3,5-Trimethylbenzoquinone (hereinafter referred to as TMHQ) is an important intermediate for the synthesis of vitamin E. There are two common synthetic methods: 1) 2,3,5-trimethylbenzoquinone (hereinafter referred to as TMBQ ) is synthesized by reduction reaction with zinc powder and sulfuric acid; 2) TMBQ is synthesized by reduction reaction with hydrogen in the presence of a noble metal catalyst. The zinc powder / sulfuric acid process reduction process will produce a large amount of waste salt by-products. Considering environmental protection, noble metal catalytic hydrogenation is more widely used at present, and palladium carbon, platinum carbon and Raney nickel catalytic direct hydrogenation are preferred. [0003] When noble metal catalysts, such as platinum and pall...

AI Technical Summary

Problems solved by technology

Although this technical solution has made great progress, the disadvantages are still obvious: 1. The highest impurity content is 0.5%, which may be enlarged in the subsequent VE preparation. The content can be enlarged by 3-5 times in the preparation of VE

2. The newly introduced catalyst deactivator is a new impurity, which has a certain impact on the subsequent VE preparation. The introduced deactivator cannot be effectively removed during TMHQ purification

Both acetone and methyl tert-butyl ether have the disadvantages of strong odor, low boiling point, large recovery loss, low flash point, flammability and explosion

[0015] There have been many research results on the solvent system for the preparation of TMHQ by catalytic hydrogenation of precious metals in China, and they have been applied in production, and have also achieved good conversion rates (generally above 95%) and selectivity (above 95%), but for different solvents The hydrogenation reaction effect of the system has its own advantages and disadvantages

Commonly used solvent systems for the preparation of TMHQ by catalytic hydrogenation of precious metals include water, low-carbon alcohols and their aqueous solutions, such as water, methanol, ethanol, isopropanol, isobutanol, etc. The advantages: the raw materials are easy to obtain and cheap, and the disadvantage is that the product purity is not high , the conversion rate is 98-99%, and 1-2% of raw materials remain; low-carbon esters, such as methyl acetate, ethyl acetate, isobutyl acetate, etc., have the advantages of high conversion rate and high selectivity, basically It can reach 99% on the surface, but the disadvantage is that the solvent recovery rate is low, the esters are easy to hydrolyze, and the solvent treatment is troublesome; the alkanes, such as pentane, heptane, hexane, cyclohexane, etc., have the advantage that the raw materials are easy to obtain, cheap and stable The disadvantage is that it is volatile, the recovery loss is large, and the flash point is low and unsafe; aromatic hydrocarbons, such as benzene, toluene, xylene, trimethylbenzene, etc., have the advantages of reaction selectivity and high product purity, and the disadvantage is that the reaction conversion rate is not high; others , such as ether, methyl tert-butyl ether, tetrahydrofuran, N,N-dimethylformamide, etc., have the advantages of low polarity, low boiling point, and are not easy to produce quinhydrone (ie, impurity 3), and the disadvantage is the safety risk of solvent recovery Large, ether compounds are prone to produce peroxides, tetrahydrofuran and N,N-dimethylformamide have a strong odor

[0016] In short, the current technical defects in the preparation of TMHQ by hydrogenation of TMBQ include: the selectivity of hydrogenation reaction needs to be further improved, the product has many impurities, and the content of impurities is high

None of the current technical means can effectively solve the

Images