Method for synthesizing chiral menthone enantiomer L-menthone and D-menthone by using L-isopulegol

A kind of technology of isopulegol and isomenthone, applied in the field of preparation of chiral menthone, can solve the problems such as limited turnover number, short catalyst life, unfavorable influence of processing environment and the like

Active Publication Date: 2018-05-08
WANHUA CHEM GRP CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although chiral menthone can be obtained, the improvement of the turnover number (TON) of this process is limited, the catalyst life is still short, and a large amount of phenol derivatives is required, which will have adverse effects on post-processing and the environment

Method used

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  • Method for synthesizing chiral menthone enantiomer L-menthone and D-menthone by using L-isopulegol
  • Method for synthesizing chiral menthone enantiomer L-menthone and D-menthone by using L-isopulegol
  • Method for synthesizing chiral menthone enantiomer L-menthone and D-menthone by using L-isopulegol

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Experimental program
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Effect test

Embodiment 1

[0040] Without taking special precautions, 3.02 mg of iridium trichloride, 0.31 mg of triphenyl phosphite, 2.46 mg of DBU phenate, and 162.37 g of L-isopulegol (95 wt %) were transferred to the reaction vessel and stirred until mixed Liquid is clear and transparent. The absolute pressure of the reaction was maintained at 0.2 MPa by feeding high-purity nitrogen gas, and the mixture was heated to 120° C. and stirred for 2 hours. Conversion and menthone yield were determined by calibrated GC analysis. The results are summarized in Table 1.

Embodiment 2

[0044] Without taking special precautions, transfer 0.98 mg of iridium acetylacetonate, 3.10 mg of triphenyl phosphite, 4.43 mg of DBU phenate and 173.14 g of L-isopulegol (98wt%) to the reaction kettle, and stir until the mixture Clear and transparent. The absolute pressure of the reaction was maintained at 0.5 MPa by feeding high-purity nitrogen, and the mixture was heated to 130° C. and stirred for 5 hours. Conversion and menthone yield were determined by calibrated GC analysis. The results are summarized in Table 1.

Embodiment 3

[0046] Without special precautions, 67.2 mg of 1,5-cyclooctadiene iridium(I) chloride dimer, 65.16 mg of triphenyl phosphite, 59.12 mg of DBU phenate, and 186.97 g of L-isopulegol (99wt%) was transferred to the reactor, stirred until the mixed solution was clear and transparent. The absolute pressure of the reaction was maintained at 1.0 MPa by feeding high-purity nitrogen gas, and the mixture was heated to 140° C. and stirred for 10 hours. Conversion and menthone yield were determined by calibrated GC analysis. The results are summarized in Table 1.

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Abstract

The invention relates to a method for synthesizing chiral menthone enantiomer L-menthone and D-menthone by using L-isopulegol. The method comprises the steps that L-isopulegol, an iridium precursor with a ligand and a phosphine coordination complex in the formula (1) are in contact in a liquid medium, an addition agent is added to a reaction system, and L-isopulegol is directly subjected to a hydrogen transfer reaction. According to the method, the selectivity of L-menthone can be remarkably improved.

Description

technical field [0001] The invention relates to the field of preparation of chiral menthone, in particular to a method for synthesizing chiral menthone enantiomers L-menthone and D-isomenthone from L-isopulegol. Background technique [0002] Natural menthone has two configurations: L-menthone and D-isomenthone: L-menthone has a menthol-like aroma with a slightly bitter taste. Although D-isomenthone also has the aroma and cool taste of menthol, it has a slightly musty and bitter taste, and if the content is too high, the overall fragrance will be deteriorated. Therefore, pure L-menthone or products with high L-menthone content have better market prospect and application value. [0003] Patent US3124614 reports that menthone can also be obtained by hydrogenating thymol under the action of Pd catalyst, but the menthone obtained by this process is a racemic product, and its smell is different from natural menthone. [0004] Patent CN106061933A reports a method for preparing me...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C45/62C07C49/407
CPCC07B2200/07C07C45/62C07C49/407
Inventor 王联防董菁张永振黎源王亚新于磊方文娟
Owner WANHUA CHEM GRP CO LTD
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