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Method for splitting D,L-menthol

A technology of menthol and menthyl esters, applied in the field of splitting D, can solve the problems of difficult industrial application, limited resolution concentration, low yield of menthyl esters, etc., and achieve the effect of facilitating industrial production

Inactive Publication Date: 2015-08-12
HUNAN LIJIE BIOCHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The traditional resolution method (US3943181) is to prepare D, L-menthol into an ester compound, form a supersaturated solution, add seed crystals to induce crystallization, but this method uses racemic menthol ester as a substrate , the yield of the obtained optically pure menthol ester is only 8%, and repeated induction crystallization is required to completely separate the two chiral configurations
[0004] In addition, the patent application documents of CN103614450A and CN1978659 disclose chiral resolution by enzymatic hydrolysis. The choice of sub-concentration makes it difficult for industrial application

Method used

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Examples

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Embodiment 1

[0027] (1) 1 g of D-menthyl benzoate with an optical purity of 40% as a substrate was dissolved in 8 mL of ethanol at 25°C, and after stirring for 30 minutes, the temperature was lowered to 0°C and stirred for 30 minutes to precipitate 260 mg of solid.

[0028] (2) Add 100 mg of the solid to a 2mol / L sodium hydroxide aqueous solution, and heat and stir at 100°C for 6 hours to perform alkaline hydrolysis to obtain D-menthol. The hydrolysate was subjected to gas phase analysis, and the optical purity of D-menthol was 98.1%.

Embodiment 2

[0030] 1 g of D-menthyl benzoate with an optical purity of 60% as a substrate was dissolved in 9 mL of ethanol at 30°C, and after stirring for 30 minutes, the temperature was lowered to 5°C and stirred for 30 minutes to precipitate 400 mg of solid.

[0031] Take 100mg of the solid and add it to a 1mol / L sodium hydroxide aqueous solution, and heat and stir at 100°C for 8 hours for alkaline hydrolysis to obtain D-menthol. The hydrolysate was subjected to gas phase analysis, and the optical purity of D-menthol was 98.5%.

Embodiment 3

[0033] 1g of D-menthyl benzoate with an optical purity of 90% as the substrate, dissolved in 8 mL of ethanol at 35°C, stirred for 30 minutes, cooled to 0°C, stirred for 30 minutes, and added optically pure D-menthyl benzoate Seed crystals were 30 mg, and stirring was continued for 30 minutes, 460 mg of solids were precipitated.

[0034] Take 100 mg of the solid and add it to a 2mol / L potassium hydroxide aqueous solution, and heat and stir at 100°C for 5 hours for alkaline hydrolysis to obtain D-menthol. The hydrolysate was subjected to gas phase analysis, and the optical purity of D-menthol was 99.0%.

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Abstract

The present invention relates to the field of chemical industry, and in particular to a method for splitting D,L-menthol. The method for splitting D,L-menthol comprises the steps of: (1) dissolving D-menthyl acrylate or L-menthyl acrylate with optical purity of 40%-90% in an organic solvent, cooling and stirring to precipitate solid; and (2) subjecting the precipitated solid to alkali hydrolysis to obtain the optically pure D- menthol or L-menthol. The step (1) can also be replaced with a step of forming a supersaturated solution of D-menthyl acrylate or L-menthyl acrylate with optical purity of 40%-90% in an organic solvent, cooling, stirring, adding seed crystals for inducing crystallization and precipitating solid. The D-menthol or L-menthol obtained by the method provided by the invention has optical purity higher than 98%, and the problem of insufficient optical purity caused by chiral induction conventional crystallization or chiral induction crystallization is well solved.

Description

Technical field [0001] The invention relates to the field of chemical engineering, in particular to a method for resolving D, L-menthol. Background technique [0002] In addition to the pungent sweetness of fresh and transparent hair, L-menthol also has a strong cooling effect. Because L-menthol has a unique fragrance and strong cooling effect, it is used in food, beverages, daily chemicals, cosmetics, It is widely used in cigarettes and medicine and has great industrial value. L-menthol can be divided into natural menthol and synthetic menthol according to its source. Natural menthol has great price fluctuations due to the influence of weather and natural conditions. Synthetic menthol has a more obvious competitive advantage due to its stable chemical composition and little price fluctuation. However, there is currently no L-menthol synthesis enterprise in China. [0003] The racemate of D, L-menthol is difficult to chiral resolution by induced crystallization or recrystallizat...

Claims

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Application Information

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IPC IPC(8): C07C27/02C07C35/12C07B57/00C07C67/52C07C69/78C07C69/76C07C69/92C07C69/14C07C201/16C07C205/57
CPCC07C29/095C07B57/00C07B2200/07C07C67/52C07C201/16C07C2601/14C07C35/12C07C69/78C07C69/76C07C69/92C07C69/14C07C205/57
Inventor 朱敏亮彭丹吴非胡汉忠
Owner HUNAN LIJIE BIOCHEM
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