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Menthyl lactate process

A technology of menthyl lactate and lactic acid, which is applied in the preparation of carboxylic acid esters, chemical instruments and methods, organic chemistry, etc., can solve the problems of unrecorded yield and unprovided synthesis details, etc.

Inactive Publication Date: 2008-10-15
利安德巴塞尔调味香料和芳香有限责任公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

This reference provides few synthetic details and does not describe the yield of ML obtained

Method used

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Examples

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Embodiment 1

[0034] Preparation of 1-menthyl lactate by esterification and controlled hydrolysis

[0035] Esterification : Add 1-menthol (1440g), L-(+)-lactic acid (2880g, from Purac's HS-88 grade, 88% lactic acid in water) and heptane (720g). The stirred mixture was brought to reflux and water was periodically drained from the trap as it formed. After 32 hours and after 854 mL of the aqueous phase had been removed, the temperature of the mixture was gradually increased to 128°C. The mixture was cooled to ambient temperature and analyzed by gas-liquid chromatography (GC). The mixture contains: 5.4% unreacted menthol, 67.7% 1-menthyl L-lactate (ML), 0.6% lactide (cyclic dimer of lactic acid), 24.6% 1- Menthyl L-lactyl-L-lactate (MLL) and 0.4% 1-menthyl L-lactyl-L-lactyl-L-lactate (MLLL).

[0036] controlled hydrolysis : The esterified product was diluted with water (4230 g) and heptane (960 g). Aqueous sodium hydroxide solution (809 g, 50% NaOH) was then added dropwise over 30 minu...

Embodiment 2

[0042] Preparation of 1-menthyl lactate by sulfuric acid-catalyzed esterification and controlled hydrolysis

[0043] Esterification : The procedure of Example 1 was generally followed, using 1000 g 1-menthol, 1000 g L-(+)-lactic acid, 500 g heptane and 6 g concentrated sulfuric acid. After 2 hours and after 300 mL of the aqueous phase had been removed, the temperature of the mixture was gradually increased to 119°C. The mixture was cooled and analyzed by GC. The mixture contained: 6.4% unreacted menthol, 57.6% ML, 0.4% lactide, 32.2% MLL and 1.9% MLLL.

[0044] controlled hydrolysis : The esterified product was diluted with water (800 g) and heptane (500 mL). Aqueous sodium hydroxide solution (204 g, 50% NaOH) was then added dropwise over 70 minutes while stirring and cooling (cold water bath) the mixture so that the temperature did not exceed 30° C. and the pH did not exceed 13.1. Separate layers. The organic layer was diluted with water (1350 g) and treated with more...

Embodiment 3

[0051] Preparation of 1-Menthanyl Lactate by Esterification Catalyzed by Sodium Bisulfate

[0052] The esterification procedure of Example 1 was generally followed using 1000 g 1-menthol, 2000 g L-(+)-lactic acid, 500 g heptane and 10 g crystalline NaHSO 4 ·H 2 O. Reflux started at about 93°C and ended at about 123°C after about 581 g of water had been expelled (taking slightly less than 17 hours). Composition of the mixture (%, GC): Menthol 3.3%, ML 48.7%, Lactide 4.8%, MLL 36.5%, MLLL 5.6%. This mixture was then used in the hydrolysis experiments described below.

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Abstract

A simple, high-yield process for making menthyl lactate (ML) is disclosed. Menthol and lactic acid react to produce a mixture comprising menthyl lactate and one or more higher lactoyl esters of ML. Hydrolysis of the esterification mixture follows in the presence of aqueous base under conditions effective to convert the higher lactoyl esters to menthyl lactate. Coincidentally, the conditions minimize hydrolysis of menthyl lactate to menthol, thereby maximizing the overall yield of ML.

Description

field of invention [0001] The present invention relates to a high yield process for obtaining menthyl lactate by esterification and controlled hydrolysis. Background of the invention [0002] Menthyl lactate (ML), an ester of menthol and lactic acid, is a physiological cooling agent widely used in flavors, oral care, and cosmetics. Recently, ML has been proposed for use in cancer therapy or as a diagnostic reagent (see, eg, US Patent Application Publication 2005 / 0054651). Since ML has four chiral centers, there are sixteen possible stereoisomers. The most common ML isomer, 1, is derived from 1-menthol and L(+)-lactic acid: [0003] [0004] Few synthetic routes to ML have been reported. A common approach involves the asymmetric reduction of menthyl pyruvate (see, e.g., Nishiyama et al., J. Chem. Soc. Chem.Commun. (1976) 101 and Ojima et al., J. Org. Chem. 42 (1977) 1671). This approach uses complex chiral reagents and produces MLs with modest chemical and optica...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C67/08C07C67/30C07C69/68
CPCC07C67/08C07C67/30C07C69/68
Inventor M·B·厄曼J·W·斯诺
Owner 利安德巴塞尔调味香料和芳香有限责任公司
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