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. Novel route and less waste

Active Publication Date: 2021-03-30
WANHUA CHEM GRP CO LTD
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  • Abstract
  • Description
  • Claims
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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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  • Preparation method of optically active menthol
  • Preparation method of optically active menthol
  • 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 Add 0.53g into a 250ml reactor, stir at 20°C for 25min, then add 46g of ethyl acetoacetate, CuSO 4 ·H 2 O Chiral phosphine d catalyst 0.117g, the temperature of the reaction system was raised to 100°C, and the reaction was kept for 9h. The conversion rate of compound A was measured by gas chromatography to be 99%, and the product was optically active compound B with an optical purity of 95ee%. Remove the catalyst in the reaction solution by filtration while it is hot, move the filtrate to a crystallization kettle, add 50g of ethyl acetate, program the temperature from 90°C to 20°C, and lower the temperature by 1°C every 5 minutes, keep filtering to obtain white crystals of compound B, optical purity It is 99.9ee%, and the single-pass crystallization yield is 95%; the mother liquor is applied mechanically, and the total yield is 99%.

[0043] The nuclear magnetic data spectrogram of the prepared comp...

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Abstract

The invention provides a preparation method of optically active menthol, wherein the preparation method comprises the following steps: 1) carrying out alkali pretreatment on a compound A (methyl 5-methyl-4-hexenoate), and cyclizing with ethyl acetoacetate under the action of a copper salt chiral phosphine catalyst to generate a compound B (methyl isomenthodienone-4-formate); 2) carrying out a decarboxylation reaction on the compound B under the action of alkali to generate a compound C (isomenthodienone); 3) reducing the compound C under the action of a catalyst to generate a compound D (isomenthyl dienol); and 4) hydrogenating the compound D under the action of chiral induction and a catalyst to generate the optically active menthol. The preparation method disclosed by the invention has the advantages of novel reaction route, readily available raw materials, low price and mild reaction conditions, and 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 cooling sensation, 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 both L-menthol, with a pure smell and cool feeling, while D-menthol has a slightly camphorous smell and obvious Spicy feeling, so pure L-menthol has a higher value. [0003] At present, optically active menthol is mainly obtained through two ways in the market, one is extraction from mint leaves, and the other is chemically directed synthesis. Due to the low content of optically active menthol contained in the mint leaf itself, the method for extracting optically active menthol has many problems such as...

Claims

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Application Information

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Patent Type & Authority Applications(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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