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A kind of preparation method of optically active menthol

An optically active, menthol technology, applied in directions such as organic chemistry methods, chemical instruments and methods, and the preparation of organic compounds, can solve problems such as low L-menthol yield, complex resolution steps, etc. The effect of novel route and cheap and easy-to-obtain raw materials

Active Publication Date: 2022-07-12
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The productive rate of this method L-menthol is lower, and resolution step is comparatively complicated

Method used

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  • A kind of preparation method of optically active menthol
  • A kind of preparation method of optically active menthol
  • A kind of preparation method of optically active menthol

Examples

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Embodiment 1

[0041] Preparation of Compound B

[0042] Take compound A 71g, Na 2 CO 3 0.53g was added to the 250ml reaction kettle, and after stirring for 25min at 20°C, 46g of ethyl acetoacetate was added, CuSO 4 ·H 2 O chiral phosphine d catalyst 0.117g, the reaction system was heated to 100°C, and the reaction was kept for 9h. The conversion rate of compound A was determined to be 99% by gas chromatography, and the product was optically active compound B with an optical purity of 95ee%. The catalyst in the reaction solution was removed by filtration while it was hot, the filtrate was transferred to a crystallization kettle, 50 g of ethyl acetate was added, the temperature was lowered by program from 90 ° C to 20 ° C, and the temperature was lowered by 1 ° C every 5 minutes, and the compound B was obtained by insulation filtration. White crystals with optical purity It is 99.9ee%, and the single-pass crystallization yield is 95%; the mother liquor is applied mechanically, and the to...

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Abstract

The invention provides a preparation method of optically active menthol, the method comprising the following steps: 1) after compound A (methyl 5-methyl-4-hexenoate) is subjected to alkali pretreatment, adding a copper salt chiral phosphine catalyst Under the effect of cyclization with ethyl acetoacetate to generate compound B (isomenthenone-4-methyl formate); 2) compound B takes place decarboxylation reaction under the effect of alkali to generate compound C (isomenthenone); 3) Compound C is reduced under the action of a catalyst to generate compound D (isomenthadienol); 4) Compound D is hydrogenated under the action of chirality induction and catalyst to yield optically active menthol. The preparation method of the invention has the advantages that the reaction route is novel, the raw materials are readily available, the price is cheap, and the reaction conditions are mild, which is suitable for industrial production.

Description

technical field [0001] The invention belongs to the field of preparation of optically active menthol, in particular to a method for preparing optically active menthol from compound A (methyl-5-methylhex-4-enoate). Background technique [0002] Menthol has a characteristic mint aroma and can produce a cool feeling, and is widely used in the fields of food, daily chemicals and medicine. Menthol has two enantiomers, L-menthol and D-menthol. Naturally extracted menthol is L-menthol, with pure odor and cooling sensation. D-menthol has a slightly camphor odor and obvious spiciness, so pure L-menthol has a higher value. [0003] Currently, optically active menthol is obtained in two ways: one is extraction from mint leaves, and the other is chemical directional synthesis. Because the content of optically active menthol contained in peppermint leaf itself is relatively low, in addition, the method for extracting optically active menthol has many problems such as low yield, cumbers...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C29/17C07C29/143C07C35/12C07C35/17C07C45/67C07C49/647C07C67/333C07C67/52C07C69/757B01J31/24
CPCC07C29/17C07C29/143C07C35/12C07C45/67C07C49/647C07C67/333C07C67/52C07C69/757B01J31/2404B01J31/2414B01J31/2461C07C2601/14C07C2601/16C07B2200/07C07C35/17
Inventor 刘连才张德旸姜鹏蔺海政张永振黎源
Owner WANHUA CHEM GRP CO LTD
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