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Method for preparing methyldopa from alpha-methyl-(3,4-dimethoxy phenyl)-alpha-aminopropionitrile by microwave hydrolysis method

A technology of dimethoxyphenyl and methyldopa, which is applied in the preparation of methyldopa by hydrolyzing α-methyl-(3,4-dimethoxyphenyl)-α-aminopropionitrile by a microwave hydrolysis method It can solve the problems of long reaction time, more acidic wastewater, and increased by-products, and achieve the effects of reducing energy and economic costs, reducing acid wastewater discharge, and improving purity and yield.

Active Publication Date: 2012-10-03
ZHEJIANG CHIRAL MEDICINE CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0013] The common disadvantages of the hydrolysis method of nitrile hydrolysis into carboxylic acid are large amount of acid, high cost, long reaction time, large energy consumption, and more acidic waste water
In addition, α-methyl-(3,4-dimethoxyphenyl)-α-aminopropionitrile (or hydrochloride) nitrile hydrolysis and demethylation hydrolysis under acidic conditions give methyldopa, It takes a long time, large dose, and high-concentration acid heating hydrolysis (and heating high-concentration acid for a long time to volatilize the acid, and needs to add acid continuously during the hydrolysis process), but this long-term, high-concentration acid heating hydrolysis will cause α -Methyl-(3,4-dimethoxyphenyl)-α-aminopropionitrile (or hydrochloride) Unknown changes in the structure of some compounds increase the by-products and decrease the purity and yield

Method used

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  • Method for preparing methyldopa from alpha-methyl-(3,4-dimethoxy phenyl)-alpha-aminopropionitrile by microwave hydrolysis method
  • Method for preparing methyldopa from alpha-methyl-(3,4-dimethoxy phenyl)-alpha-aminopropionitrile by microwave hydrolysis method

Examples

Experimental program
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Effect test

Embodiment 1

[0049] In a two-neck flask equipped with a thermometer and a stirrer, add 20.7 g (0.051 mol) of 9% concentrated hydrochloric acid. Cool to 0~5°C with ice water. Slowly add 2.18 g (0.0085mol) of DL-2-amino-3-(3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride [or L-2-amino-3-( 3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride, the same for the following examples] was dissolved in ice-cold concentrated hydrochloric acid. Stir vigorously for 1-2 hours after addition. Warm up to room temperature after the reaction is complete. The reaction mixture was placed in a chemical experiment temperature-controlled microwave instrument, and irradiated for 15 minutes at a microwave power of 250 watts. After the reaction was completed, the temperature was raised to room temperature, and N was directly introduced into the reaction mixture slowly. 2 , while extracting excess HCl by distillation under reduced pressure. Adjust the pH value of the solution with ammonia water an...

Embodiment 2

[0052] In a two-neck flask equipped with a thermometer and a stirrer, add 10.3 g (0.051 mol) of 18% concentrated hydrochloric acid. Cool to 0~5°C with ice water. Slowly add 2.18 g (0.0085mol) of DL-2-amino-3-(3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride [or L-2-amino-3-( 3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride, the same for the following examples] was dissolved in ice-cold concentrated hydrochloric acid. Stir vigorously for 1-2 hours after addition. Warm up to room temperature after the reaction is complete. The reaction mixture was placed in a chemical experiment temperature-controlled microwave instrument, and irradiated for 15 minutes at a microwave power of 250 watts. After the reaction was completed, the temperature was raised to room temperature, and N was directly introduced into the reaction mixture slowly. 2 , while extracting excess HCl by distillation under reduced pressure. Adjust the pH value of the solution with ammonia water a...

Embodiment 3

[0055] In a two-necked flask equipped with a thermometer and a stirrer, add 34.4 grams (0.051 mol) of 12% hydrobromic acid. Cool to 0~5°C with ice water. Slowly add 2.18 g (0.0085mol) of DL-2-amino-3-(3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride [or L-2-amino-3-( 3,4-dimethoxyphenyl)-2-methyl-propionitrile hydrochloride, the same for the following examples] was dissolved in ice-cold concentrated hydrochloric acid. Stir vigorously for 1-2 hours after addition. Warm up to room temperature after the reaction is complete. The reaction mixture was placed in a chemical experiment temperature-controlled microwave instrument, and irradiated for 15 minutes at a microwave power of 250 watts. After the reaction was completed, the temperature was raised to room temperature, and N was directly introduced into the reaction mixture slowly. 2, while extracting excess hydrobromic acid by distillation under reduced pressure. Adjust the pH value of the solution with ammonia wat...

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Abstract

The invention belongs to the technical field of one critical step in microwave nitrile hydrolysis and demethylation hydrolysis of chemical synthesis medicine methyldopa [alpha-methyl-(3,4-dyhydroxy phenyl)-alpha-aminopropionic acid, similarly hereinafter] or synthetic chiral medicine L-methyldopa [L-alpha-methyl-(3,4-dyhydroxy phenyl)-alpha-aminopropionic acid, similarly hereinafter], i.e. the chemical reaction for preparing methyldopa or L-methyldopa from alpha-methyl-(3,4-dimethoxy phenyl)-alpha-aminopropionitrile or L-alpha-methyl-(3,4-dimethoxy phenyl)-alpha-aminopropionitrile through microwave nitrile hydrolysis and demethylation hydrolysis. The microwave hydrolysis uses low-concentration hydrochloric acid or hydrobromic acid, so the energy sources and the economic cost are reduced, the acid wastewater discharge is reduced, by-products are reduced, and the purity and the yield of products are improved.

Description

[0001] technical field [0002] The technical field of the present invention belongs to the chemical synthesis drug methyldopa [Methyldopa, α-methyl-(3,4-dihydroxyphenyl)-α-alanine, the same below] or the synthetic chiral drug L-methyldopa One of the key steps in [L-methyldopa, L-α-methyl-(3,4-dihydroxyphenyl)-α-alanine, the same below]: microwave nitrile hydrolysis and demethylation hydrolysis Reaction; i.e. α-methyl-(3,4-dimethoxyphenyl)-α-aminopropionitrile or L-α-methyl-(3,4-dimethoxyphenyl)-α-amino The chemical reaction of propionitrile to prepare methyldopa or L-methyldopa by microwave nitrile group hydrolysis and demethylation hydrolysis. [0003] Background technique [0004] L-Methyldopa is a catecholamine hormone in organisms and is a decarboxylase inhibitor [SLETA INGER M, CHEMERDA J M, W BOLL INGER F. Potent decarboxylase inhibitors. analogs of methyldopa [ J ]. J Med Chem, 1963, 6 ( 2) : 1012103.], has antihypertensive effect, and is clinically used to treat ...

Claims

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Application Information

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IPC IPC(8): C07C229/36C07C227/18
Inventor 徐伟亮徐子河汪静黄有明
Owner ZHEJIANG CHIRAL MEDICINE CHEM
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