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Method for continuously preparing stereoisomer mixture containing racemic menthol

A technology of stereoisomers and menthol, applied in the field of organic synthesis, can solve the problems of complex catalyst preparation procedures, harsh operating conditions, and short service life, and achieve the effects of low price, low production cost, and long service life

Active Publication Date: 2015-03-25
SHANDONG NHU PHARMA +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0012] As can be seen from the above, the existing technical methods for preparing racemic menthol have the following defects: 1, the reaction process, accompanied by more by-products; 2, the reaction must be carried out under high temperature and pressure, which requires high equipment. The operating conditions are harsh; 3. Use precious metals or rare metals as catalysts, and the catalyst preparation procedures are complicated, the service life is short, and the production cost is high

Method used

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  • Method for continuously preparing stereoisomer mixture containing racemic menthol
  • Method for continuously preparing stereoisomer mixture containing racemic menthol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0041] A method for the continuous preparation of a mixture of stereoisomers comprising racemic menthol comprising the steps of:

[0042] Catalyst preparation:

[0043] a. Dissolution of metal salts:

[0044] 1.2g NiCl 2 and 1.0 g ZnCl 2 Add to the 1L four-neck flask, add 200g of distilled water to dissolve.

[0045] b. Impregnation of porous carrier materials:

[0046] Add 50g specific surface area is 200m 2 / g of commercially available SiO 2 (Particle size 20-40 mesh), stirred and impregnated at 80°C for 2h.

[0047] c. Drying:

[0048] Transfer to an oven at 150°C for drying.

[0049] d. with BH 4 - Contact reduction of ions in aqueous solution:

[0050] Then slowly add 1.0mol / L KBH dropwise under nitrogen protection and stirring in an ice-water bath at 0°C 4 Solution 50ml, the reaction proceeds immediately and releases hydrogen.

[0051] e. Adjust pH:

[0052] After the reaction, the catalyst was washed with distilled water to pH = 7, and then washed 3 times ...

Embodiment 2

[0071] The specific surface area of ​​20g is 500m 2 / g of commercially available activated carbon (particle size 20-40 mesh) was added to a 1L four-neck flask, 200g of distilled water was added, and 19g of Ni(NO 3 ) 2 and 3.0 g LaCl 3 , stirring, dissolving and impregnating at 90°C for 5 hours, transferring to an oven for drying at 120°C, and then slowly adding 2.0mol / L KBH dropwise under nitrogen protection and stirring in an ice-water bath at 0°C 4 The solution was 100ml, and the reaction proceeded immediately and released hydrogen gas. After the reaction, the catalyst was washed with distilled water until PH = 7, and then washed 3 times with absolute ethanol. The Ni-La-B / C amorphous alloy catalyst was obtained, and the mass percentages of Ni, La and B in the catalyst were detected by inductively coupled plasma emission spectrometer (ICP) Ni: 19%; La: 6.5%; B: 8 %.

[0072] The reaction was carried out in a high-pressure light oil hydrogenation micro-reaction device prod...

Embodiment 3

[0081] The specific surface area of ​​20g is 655m 2 / g of commercially available activated carbon (particle size 20-40 mesh) was added to a 1L four-neck flask, 300g of distilled water was added, and 12g of Ni(NO 3 ) 2 and 2.0g Sc(NO 3 ) 3 , stirring, dissolving and impregnating at 80°C for 5 hours, transferring to an oven for drying at 120°C, and then slowly adding 4.0mol / L NaBH dropwise under nitrogen protection and stirring in a constant temperature bath at 20°C 4 Solution 50ml, the reaction proceeds immediately and releases hydrogen gas. After the reaction, the catalyst is washed with distilled water until pH = 7, and then washed 3 times with absolute ethanol. The Ni-Sc-B / C amorphous alloy catalyst was obtained, and the mass percentages of Ni, Sc and B in the catalyst were detected by inductively coupled plasma emission spectrometer (ICP) Ni: 12%; Sc: 1.9%; B: 6 %.

[0082] The reaction was carried out in a high-pressure light oil hydrogenation micro-reaction device pr...

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Abstract

The invention discloses a method for continuously preparing a stereoisomer mixture containing racemic menthol. The method comprises the following steps: preparing a catalyst and preparing the stereoisomer mixture containing racemic menthol. The preparation of the catalyst comprises the following steps: dissolving a metal salt, soaking a porous carrier material, drying, performing contact reduction with an aqueous solution of BH4<->ion, and adjusting the pH value; and the preparation of the stereoisomer mixture containing racemic menthol comprises the following steps: adding a catalyst, replacing nitrogen with hydrogen, pumping raw materials and separating. In the mixture prepared by the method disclosed by the invention, the content of impurity hydrocarbons is 0.2-0.8% and the content of L,D-menthol is 65.5-68.5%.

Description

technical field [0001] The invention belongs to the technical field of organic synthesis, in particular to a method for continuously preparing a stereoisomer mixture containing racemic menthol. Background technique [0002] D, L-menthol (racemic menthol) is an important terpene chiral spice. L-menthol is the main component of peppermint oil. It is widely used in spices and seasonings due to its cooling and cooling effects pharmaceutical and pharmaceutical industries. D, L-menthol and stereoisomers: D, L-neomenthol, D, L-isomenthol and D, L-neoisomenthol, the smell is slightly inferior to L-menthol, their synthesis has been has received widespread attention since. The mixture of these 4 pairs of menthol stereoisomers can be separated to obtain the racemic form of D, L-menthol, and the optically pure L-menthol can be obtained after resolution. [0003] The 8 isomers of menthol are summarized as follows: [0004] [0005] [0006] Patent No. DE2314813A1 describes the ...

Claims

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Application Information

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IPC IPC(8): C07C35/12C07C29/56B01J23/80B01J23/83B01J23/755
CPCB01J23/755B01J23/80B01J23/83B01J2523/27B01J2523/305B01J2523/35B01J2523/36B01J2523/3706B01J2523/3712C07C29/56C07C2601/14C07C35/12
Inventor 赵文乐周剑平马啸杨影管亚军方万军于明袁金桃邵卫康
Owner SHANDONG NHU PHARMA
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