Preparation method of L-menthol

Abstract

The invention discloses a preparation method of L-menthol. The preparation method comprises the following steps: 1) adding 3-methyl-6-isopropyl-phenol and a composite noble metal catalyst to a high-pressure kettle, wherein the composite noble metal catalyst is formed by the combination of a Raney nickel catalyst RTH211, palladium carbon, cyclodextrin and Cu / SiO2; closing the high-pressure kettle; filling hydrogen to replace the air in the kettle for two to three times; finally filling hydrogen to enable pressure in the kettle to be 5.0 to 8.0MPa; controlling the temperature to be 100 to 150 DEG C for 4 to 6 hours, thus obtaining a mixture of menthol; rectifying to obtain D,L-menthol; 2) performing esterification reaction on D,L-menthol and an acylation reagent under the effect of alkali so as to obtain D,L-menthol ester; 3) performing hydrolysis reaction on D,L-menthol ester under the effect of hydrolytic enzyme, thus obtaining L-menthol, wherein the hydrolytic enzyme is cellularized burkholderia cepacia (B.cepacia ATCC25416). The preparation method has the advantages that the production raw materials are simple and easy to obtain; the prepared L-menthol is high in yield and lower in cost and suitable for mass production and use.

Description

Technical field [0001] The invention belongs to the technical field of perfume production. More specifically, the present invention relates to a method for preparing L-menthol. Background technique [0002] I-menthol is not only an important additive in the pharmaceutical, food and cosmetic industries, but also an indispensable chiral precursor for the synthesis of chiral materials. The development of I-menthol is important for promoting the technological progress of my country’s fragrance industry and the pharmaceutical industry. The development of the company has important strategic significance. Natural menthol is I-menthol. Due to the influence of weather and region, the output and quality fluctuate greatly. The quality of synthetic menthol products is stable. The quality of I-menthol obtained after enantiomeric separation is The difference from natural products is very small, so it has received extensive attention in recent years. Since the 1920s, people have used various m...

AI Technical Summary

Problems solved by technology

In summary, in the current preparation methods of L-menthol, there are problems such as raw materials are not easy to obtain, D, L-menthol resolution efficiency is not high, etc.