Refining method of methyl or ethyl vanillin

Abstract

The invention relates to a refining method of a compound, in particular to a refining method of methyl or ethyl vanillin, which comprises the following steps: adopting a mixed solvent consisting of liquid alkane or petroleum ether and toluene for carrying out re-crystallization on a methyl or ethyl vanillin crude product containing a byproduct of o-methyl or ethyl vanillin, leading the methyl or ethyl vanillin to crystallize and precipitate and remaining the o-methyl or ethyl vanillin in mother liquor. Compared with the prior art of purely adopting the toluene as the re-crystallization solvent, the adoption of the method can reduce the using quantity of the toluene to below 1 / 2 of the original using quantity and lead the re-crystallization yield of the methyl or ethyl vanillin to be more than 90%, which is improved by about 20% in comparison with the prior art; furthermore, the product has the advantages of good color and luster, low viscosity of the mother liquor after devitrification, convenient discharge on production and low production cost, and is applicable to industrial applications.

Description

technical field [0001] The present invention relates to a method for refining compounds, in particular to a method for refining methyl or ethyl vanillin. Background technique [0002] Methyl vanillin (4-hydroxy-3-methoxybenzaldehyde) and ethyl vanillin (4-hydroxy-3-ethoxybenzaldehyde) are important fragrances, widely used in cosmetics, soaps, beverages , cigarettes and baked goods industries. At the same time, they are important chemical intermediates and raw materials, and are widely used in pesticide synthesis and electroplating. [0003] At present, the synthesis of methyl or ethyl vanillin usually adopts the guaiacol route, that is, guaiacol (o-methoxyphenol) or ethyl guaiacol (o-ethoxyphenol) and acetaldehyde The acid is used as the starting material, and it is prepared by condensation, oxidation, and decarboxylation. The synthetic route is as follows: [0004] [0005] Owing to the by-product o-methyl or ethyl vanillin will be generated during the synthesis proc...

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Problems solved by technology

[0007] But said method has following shortcoming: adopt toluene as the recrystallization solvent of crude product, because the mother liquor after the crystallization is viscous paste, is unfavorable for producing upper discharge, for easy operation, has to increase toluene consumption in production (Add at least 3.3mL of toluene per 1g of crude product), but the recrystallization yield will be affected, generally only about 70%; from cost considerations, the mother liquor after crystallization has to be evaporated to remove the toluene and rectified again To reclaim methyl or ethyl vanillin, this not only increases energy consumption and other costs, but also because methyl or ethyl vanillin is a heat-sensitive substance, it is easily oxidized into acid or polymerized by heating during the distillation process, which will cause Product yield decreased

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