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A kind of synthetic method of racemic menthol and its derivatives

A synthesis method and menthol technology are applied in the synthesis field of racemic menthol and derivatives thereof, can solve the problems of high equipment requirements, harsh operating conditions, and cannot reuse hydrocarbon by-products, etc., and achieve a simple process and a green process. Effect

Active Publication Date: 2017-10-10
SHANGHAI WANXIANG FLAVORS & FRAGRANCES
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0007] The conditions for catalytic hydrogenation or isomerization of compounds with menthane carbon skeletons described so far are either reacted in organic solvents, or carried out at high temperature and under excessive pressure, so the equipment requirements are high, the operating conditions are harsh, and it is easy to Causes hydrogenolysis of hydroxyl groups in menthol to generate hydrocarbon by-products that cannot be reused; or requires the use of noble metals as catalysts

Method used

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  • A kind of synthetic method of racemic menthol and its derivatives
  • A kind of synthetic method of racemic menthol and its derivatives

Examples

Experimental program
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Effect test

Embodiment 1

[0022] 25g of chlorobenzene was heated to 125°C, and a mixture of 7.6g of citronellol and 7g of di-tert-butyl peroxide was added dropwise under stirring, the addition was completed in 4 hours, and the reaction was continued at 125°C for 14 hours. Gas chromatography detection showed that the conversion rate of citronellol was 57.1%, and the ratio of racemic menthol / neomenthol / isomenthol / menthone / isopulegol was 12.93:1.65:5.31:12.03:3.85. The ratio of menthone to isomenthone is 7.66:4.37. The total selectivity of racemic menthol and its isomers was 34.83%; the selectivity of menthone was 21.64%. The selectivity of isopulegol was 6.74%.

Embodiment 2

[0024] 50g of diphenyl ether, heated to 160°C, added dropwise a mixture of 13g of citronellol, 10g of di-tert-butyl peroxide and 4g of tert-butyl hydroperoxide (70% aqueous solution) under stirring, and the addition was completed in 2 hours. The reaction was continued at 160°C for 12 hours. Gas chromatography detection showed that the conversion rate of citronellol was 81.9%, and the ratio of menthol / neomenthol / isomenthol / menthone / isopulegol was 9.54:2.71:2.25:3.16:19.18. The total selectivity of racemic menthol and its isomers was 17.7%; the selectivity of isopulegol was 23.4%.

Embodiment 3

[0026] 10g of n-decane was heated to 140°C, and a mixture of 3.2g of citronellol and 3g of di-tert-butyl peroxide was added dropwise with stirring, and the addition was completed in 3 hours, and the reaction was continued at 140°C for 8 hours. Gas chromatography detection showed that the conversion rate of citronellol was 68.3%, and the ratio of racemic menthol / neomenthol / isomenthol / menthone / isopulegol was 17.4:3.92:7.83:10.53:2.85. The ratio of menthone to isomenthone is 6.87:3.66. The total selectivity of racemic menthol and its isomers was 42.68%; the selectivity of menthone was 15.4%. The selectivity of isopulegol was 4.17%.

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Abstract

The invention discloses a synthetic method of racemic menthol and derivatives thereof. The synthetic method is characterized by comprising the following steps of adopting citronellol as raw materials, and carrying out intramolecular free radical addition reaction in a solvent at a certain temperature under the action of a peroxide free radical initiator to obtain the racemic menthol; meanwhile, obtaining a certain amount of isomer neomenthol, isomenthol, derivative menthone and isopulegol of the racemic menthol. Compared with the prior art, the synthetic method of the racemic menthol and the derivatives thereof has the following advantages that (1) no waste water is produced during a reaction process, and the technology is simple and green; (2) according to the method provided by the invention, the racemic menthol, and the isomer neomenthol, the isomenthol, the menthone and the isopulegol of the racemic menthol can be produced at the same time.

Description

technical field [0001] The invention belongs to the field of organic synthesis, and in particular relates to a synthesis method of racemic menthol and derivatives thereof. Background technique [0002] As a naturally occurring cyclic terpene alcohol, L-menthol is one of the main components of peppermint oil; due to its cooling and cooling effects, it is widely used in flavor formulations and seasonings, and is also widely used in medicine. Racemic menthol and its several stereoisomers neomenthol, isomenthol and menthone are also widely used as raw materials for the deployment of refreshing flavors. Therefore, their synthesis has attracted extensive attention. Disclosed in EP0563611A1, an aromatic or alicyclic compound with a menthane carbon skeleton containing at least one C=C double bond and an oxygen atom connected at the 3-position is loaded on a carrier such as a rare earth metal oxide with precious metal ruthenium, palladium or rhodium , at a temperature of 180-240° C...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C35/12C07C29/03C07C49/407C07C45/00
CPCC07B2200/07C07C29/03C07C45/00C07C35/12C07C49/407
Inventor 黄战鏖侯峰钱正刚裴继红张长征
Owner SHANGHAI WANXIANG FLAVORS & FRAGRANCES
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