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Method for preparing L-menthol

A technology for menthol and isopulegol, applied in the field of preparing L-menthol, can solve problems such as catalyst instability, lack of industrial value, and inability to reuse, achieve significant innovation, reduce production costs, and mild reaction conditions Effect

Inactive Publication Date: 2013-05-08
上海统益生物科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But the catalyst itself is very unstable and cannot be reused, so it has no industrial value

Method used

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  • Method for preparing L-menthol
  • Method for preparing L-menthol
  • Method for preparing L-menthol

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0034] Add 500 grams of zinc bromide aqueous solution with a weight concentration of 5% in a 1000 mL dry three-port reactor equipped with a thermometer and magnetic stirring, then add 20 grams of NaY type molecular sieves to the aqueous solution, and then the system is sealed at 100 °C for 2 hours. After completion of the reaction, water was concentrated and removed under reduced pressure, and dried at 200°C, followed by calcination at 400°C for 2 hours to obtain the catalyst.

Embodiment 2

[0036] Adding 250 grams of zinc bromide aqueous solution with a weight concentration of 10% in a 1000 mL dry three-port reactor equipped with a thermometer and magnetic stirring, followed by adding 25 grams of NaY type molecular sieves to the aqueous solution, and then the system was sealed at 50 °C for 4 hours. After the reaction, the water was concentrated and removed under reduced pressure, and dried at 100° C., followed by roasting at 600° C. for 0.5 hour to obtain the catalyst.

Embodiment 3

[0038] Add the catalyst 50g of embodiment 1, 200mL of anhydrous toluene in 500mL equipped with thermometer, dropping funnel, magnetic stirring dry three-port reactor full of nitrogen, 50g of citronellal (ee value 99%) is transferred to constant Then drop it into the system in the pressure dropping funnel, and keep stirring vigorously, and the temperature of the system is controlled between -5-0°C. Stirring was continued at this temperature for 2 hours after the dropwise addition was complete. After the reaction was completed, the mixture was filtered to obtain a colorless clear liquid, and the filter cake was recovered for use. Then the organic phase was washed with 2*20 mL of deionized water, dried with 20 mL of saturated sodium chloride aqueous solution, and then dried over anhydrous sodium sulfate, filtered to remove inorganic salts, and the solvent was concentrated. Subsequently, the product was fractionated under reduced pressure (20 cm long to the thorn distillation col...

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Abstract

The invention discloses a method for preparing L-menthol, which comprises the following steps:(1) reacting d-citronellal in a solvent in the presence of a catalyst, and collecting isopulegol from the reaction product, wherein the catalyst is a zinc-bromide-modified NaY molecular sieve; and carrying out high-pressure hydrogenation on the obtained isopulegol to obtain the target product L-menthol. The obtained isopulegol can be subjected to high-pressure hydrogenation to obtain the target product L-menthol without purification. The invention has the characteristics of mild reaction conditions, high stereoselectivity, high yield and the like, and is simple to operate; and the catalyst is simple to recover, and can be used repeatedly. The method disclosed by the invention avoids the problems of difficulty in product purification, low yield and the like in the traditional synthesis technique of the compounds, and greatly lowers the production cost.

Description

technical field [0001] The invention relates to a method for preparing L-menthol. Background technique [0002] L-menthol, also known as L-menthol, its chemical name is (1R,2S,5R)-2-isopropyl-5-methyl-1-cyclohexanol, its English name is L-menthol, and its structural formula is as follows : [0003] [0004] L-menthol is a cyclic monoterpene alcohol structure substance with very obvious physiological activity, and it is widely used in 1. local infiltration anesthesia, surgical anesthesia, postoperative analgesia, etc.; 2. nerve block: costal Internerve block, trigeminal nerve block, occipital nerve block, etc.; 3. Intractable pruritus skin diseases: neurodermatitis, etc. Menthol is a saturated cyclic alcohol, which may interact with nerve cell membrane lipids, causing changes in membrane lipid structure, preventing Na+ influx, inhibiting depolarization, and preventing nerve cells from generating spreading action potentials, thereby generating local Nerve blockade. At t...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07C35/12C07C29/17C07C35/17C07C29/56B01J29/08
CPCY02P20/584
Inventor 严政军刘熠
Owner 上海统益生物科技有限公司
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