Menthol purification method

A purification method and a menthol technology are applied in the directions of organic chemistry methods, separation/purification of hydroxyl compounds, organic chemistry, etc., which can solve the problems such as cumbersome freezing crystallization technology, and achieve the advantages of shortening nucleation time, increasing content and increasing optical rotation. Effect

Pending Publication Date: 2020-04-14
安徽恒达药业有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The purpose of the present invention is to provide a kind of purification method of menthol for the complicated problem of existing frozen crystallization technology

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0020] A method for purifying menthol, comprising the following:

[0021] (1) Prepare by mixing compound solvent and menthol raw material, heat to 28°C and dissolve to obtain a compound solution with a concentration of menthol raw material of 0.3 g / mL, adjust the compound solution to a pH value of 5.8 with sodium carbonate, and obtain an acidic compound solution, Add the acidic composite solution into the crystallizer for subsequent use; the composite solvent includes the following raw materials in parts by weight: 21 parts of dimethylformamide, 5 parts of ethyl acetate, 1.2 parts of sodium carboxymethyl cellulose; the external device of the crystallizer Three ultrasonic generators, the three ultrasonic generators are evenly distributed on the same level, and the ultrasonic power of the ultrasonic generators is 400W continuously adjustable;

[0022] (2) The crystallization process is divided into three stages

[0023] (2.1) Control the cooling rate to 1°C / min, and cool down t...

Embodiment 2

[0028] A method for purifying menthol, comprising the following:

[0029] (1) Prepare by mixing compound solvent and menthol raw material, heat to 26°C and dissolve to obtain a compound solution with a concentration of menthol raw material of 0.25 g / mL, adjust the compound solution to a pH value of 5.6 with sodium carbonate, and obtain an acidic compound solution, Add the acidic composite solution into the crystallizer for subsequent use; the composite solvent includes the following raw materials in parts by weight: 24 parts of dimethylformamide, 4 parts of ethyl acetate, 1.6 parts of sodium carboxymethyl cellulose; Two ultrasonic generators, the two ultrasonic generators are evenly distributed on the same level, and the ultrasonic power of the ultrasonic generators is 500W continuously adjustable;

[0030] (2) The crystallization process is divided into three stages

[0031] (2.1) Control the cooling rate to 1°C / min, and cool down to 24°C;

[0032] (2.2) Start the ultrasoni...

Embodiment 3

[0035] A method for purifying menthol, comprising the following:

[0036] (1) Prepare by mixing compound solvent and menthol raw material, heat to 26-30°C to dissolve to obtain a compound solution with a concentration of menthol raw material of 0.25-0.35g / mL, and adjust the compound solution to a pH value of 5.6-6.0 with sodium carbonate , to obtain an acidic composite solution, the acidic composite solution is added to the crystallizer for subsequent use; the composite solvent includes the following raw materials in parts by weight: 18 parts of dimethylformamide, 6 parts of ethyl acetate, 0.8 part of sodium carboxymethylcellulose; Three ultrasonic generators are installed outside the crystallizer, and the ultrasonic power of the ultrasonic generator is continuously adjustable at 300W;

[0037] (2) The crystallization process is divided into three stages

[0038] (2.1) Control the cooling rate to 1°C / min, and cool down to 24°C;

[0039] (2.2) Start the ultrasonic generator, ...

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Abstract

The invention belongs to the technical field of menthol purification, and particularly relates to a menthol purification method which comprises the following steps: preparing a composite solution froma composite solvent and a menthol raw material, and assisting ultrasonic treatment in the crystallization process, wherein a plurality of crystallization processes are adopted, so that the purification degree of menthol can be improved. Compared with the prior art, the method has the following advantages that: by reasonably preparing the solvent and cooperating with the effect of an ultrasonic generator, the properties of a crystal growth interface can be affected, the size and structural form of growth elements of crystals can be effectively controlled, then the nucleation time can be shortened, the menthol purity can be improved, the optical rotation can be improved, and it shows that the content of L-menthol is increased, and the quality of menthol crystals is greatly improved.

Description

technical field [0001] The invention belongs to the technical field of menthol purification, in particular to a method for purifying menthol. Background technique [0002] Menthol is a colorless and transparent crystal or crystalline powder, the main chemical component is menthol, the melting point is 41-44 ° C, extracted from the leaves and stems of mint, volatile, easily soluble in ethanol, chloroform, ether, liquid paraffin or volatile oil; China is the main natural peppermint producer, and the annual output of peppermint oil reaches 2000-3000t, which is widely used; the purity of commercially available menthol is about 95%, and trace impurities therein will also affect the quality of menthol; therefore It is necessary to further purify menthol. The prior art uses freeze crystallization technology to purify menthol. During the cooling and crystallization process, the cooling rate should be controlled. If the cooling is too fast, the peppermint oil will condense and not cr...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C29/78C07C35/12
CPCC07C29/78C07C2601/14C07B2200/13C07C35/12
Inventor 张涛
Owner 安徽恒达药业有限公司
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