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Chiral nitrogen-phosphorus ligand and preparation method thereof, and method for splitting racemic menthol

A technology of menthol and nitrogen and phosphorus is applied in the field of obtaining chiral menthol through kinetic resolution, can solve the problems of low yield, harsh conditions, low optical purity and the like, achieves low catalyst cost, simple equipment requirements, The effect of high product yield

Active Publication Date: 2019-04-19
WANHUA CHEM GRP CO LTD +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0010] The purpose of the present invention is to develop a method to improve the quality of L-menthol by kinetic resolution, aiming at many problems such as low optical purity, low yield and harsh conditions of L-menthol and D-menthol in the existing production technology. Improvement of Optical Purity of Alcohol and D-Menthol

Method used

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  • Chiral nitrogen-phosphorus ligand and preparation method thereof, and method for splitting racemic menthol
  • Chiral nitrogen-phosphorus ligand and preparation method thereof, and method for splitting racemic menthol
  • Chiral nitrogen-phosphorus ligand and preparation method thereof, and method for splitting racemic menthol

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Experimental program
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Effect test

Embodiment i

[0057]

[0058] N-bromosuccinimide NBS (34.0 mmol) was added in portions to a solution of compound 1a (30.9 mmol) in dichloromethane (300 mL) at room temperature. After stirring at 30° C. for 2 hours, dichloromethane was removed from the reaction solution under reduced pressure, and the residue was further purified by distillation under reduced pressure to obtain compound 2a (96% yield).

[0059]

[0060] At room temperature, add compound 2 (34.0mmol), substituted phenylboronic acid 3 (34.0mmol), tetrakis (triphenylphosphine) palladium (3.4mmol), potassium carbonate (34.0mmol), 1,4-diox Hexacyclic (200 mL) and water (100 mL). Heating to reflux for 3 hours, after cooling, the reaction solution was filtered with diatomaceous earth, the filtrate was back-extracted with dichloromethane, the organic phase was concentrated under reduced pressure, and the raffinate was recrystallized with dichloromethane / n-hexane to obtain compound 4 (yield 98%).

[0061]

[0062] Add comp...

Embodiment 1

[0096] In a 2L stainless steel (316L material) reaction kettle, add 1.34 grams of (1,5-cyclooctadiene) iridium (I) dichloride dimer, 156.27 grams of tetrahydrofuran, 1.932 grams 201.6 grams of allyl acetate and 156.27 grams of racemic menthol; keep the stirring speed at 800 rpm, and react at 25°C for 2 hours. After the reaction solution was cooled to room temperature, the reaction solution was taken out, filtered with a Bourg-style funnel, and the solid was filtered out, and 40 wt% aqueous sodium hydroxide solution and 156.27 g of tetrahydrofuran were added to the solid with the same mass as the solid, stirred for 0.5 h, and left to stand For a period of time, the reaction solution was subjected to rotary evaporation, and finally vacuum distillation to obtain pure L-menthol, and the filtrate filtered by the Buchner funnel was poured out and spin-dried, and vacuum distillation was obtained to obtain pure D-menthol. Sampling Analysis, the results are shown in Table 1.

Embodiment 2

[0098] In a 2L stainless steel (316L material) reaction kettle, add 67.17 grams of (1,5-cyclooctadiene) iridium (I) dichloride dimer, 156.27 grams of tetrahydrofuran, 96.636 grams 201.6 grams of allyl acetate and 156.27 grams of racemic menthol; keep the stirring speed at 800 rpm, and react at 25°C for 2 hours. After the reaction solution was cooled to room temperature, the reaction solution was taken out, filtered with a Bourg-style funnel, and the lower layer of solid was removed, and 40 wt% aqueous sodium hydroxide solution and 156.27 g of tetrahydrofuran were added to the solid, stirred for 0.5 h, and then allowed to stand for a period of time. time, the reaction solution was subjected to rotary evaporation, and finally vacuum distillation to obtain pure L-menthol. The upper layer of the Buchner funnel was poured out and spin-dried, and finally vacuum distillation was obtained to obtain pure D-menthol. Sampling and analysis , the results are shown in Table 1.

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Abstract

The invention relates to a chiral nitrogen-phosphorus ligand and a preparation method thereof, and a method for splitting racemic menthol. According to the splitting method, racemic menthol reacts with allyl ester under the action of a catalyst formed by transition metal salt and a chiral nitrogen-phosphorus ligand, so as to obtain chiral L-menthol and D-menthol under the action of a catalyst formed by a transition metal salt and a chiral nitrogen-phosphorus ligand. The optical purity of the pure L-menthol and D-menthol is greater than 99%, and the yield is greater than 95%.

Description

technical field [0001] The invention relates to a method for resolving menthol, in particular to a method for obtaining chiral menthol through dynamic resolution. Background technique [0002] Menthol is an important aroma chemical, which has a strong cooling effect and is widely used in cosmetics, food, beverage, medicine and other fields, and is one of the most important synthetic fragrances in industry. [0003] There are two enantiomers of menthol, D-menthol and L-menthol. Naturally extracted menthol is both L-menthol, with pure smell and cool feeling. The current market demand is L-menthol; D-menthol Alcohol has a musty smell and obvious spicy feeling, but D-menthol has a strong antibacterial effect. [0004] At present, L-menthol in the market mainly comes from the planting and extraction of natural mint plants. Affected by unpredictable factors such as climatic conditions, its output, quality and product price often fluctuate violently, which has a negative impact on...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07F9/653C07F15/00B01J31/22C07C29/10C07C35/12
CPCB01J31/2404B01J2531/827C07B2200/07C07C29/10C07C41/16C07F9/65324C07F15/0033C07C2601/14C07C35/12C07C43/188
Inventor 李康董菁张德旸张永振黎源王联防
Owner WANHUA CHEM GRP CO LTD
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