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Method for synthesizing 5-methylpyrazine-2-carboxylic acid

A technology of methylpyrazine and hydroxymethylpyrazine, applied in the direction of organic chemistry, etc., can solve problems such as the difficulty in industrial design of electrochemical methods, and achieve the effects of low cost, high yield, and reduced side reactions

Inactive Publication Date: 2011-09-21
自贡市华气化学制品有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The highest yield of electrochemical method is as high as 93%, but the industrial design of electrochemical method is difficult

Method used

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  • Method for synthesizing 5-methylpyrazine-2-carboxylic acid
  • Method for synthesizing 5-methylpyrazine-2-carboxylic acid
  • Method for synthesizing 5-methylpyrazine-2-carboxylic acid

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Experimental program
Comparison scheme
Effect test

Embodiment 1

[0044] Embodiment 1 carries out following processing step in sequence:

[0045]Add 12.4g of 2-methyl-5-hydroxymethylpyrazine (0.1mol), 50ml of water, and 0.15g of ammonium metavanadate to a 250ml three-necked flask, raise the temperature to 100°C, add 29g (0.3mol) of 65% nitric acid dropwise, for 1h After dripping, keep reflux for 4 hours, cool to room temperature; neutralize with 30% sodium hydroxide aqueous solution to pH = 2.0, distill off about 50g of water under reduced pressure, and extract with butanone three times, each time using 50ml of butanone, Then, butanone was distilled off to obtain 8.28 g of 5-methylpyrazine-2-carboxylic acid, the liquid chromatography analysis was 99.6%, and the yield was 60%.

Embodiment 2

[0046] Embodiment 2 carries out following processing steps in sequence:

[0047] Add 12.4g 2-methyl-5-hydroxymethylpyrazine (0.2mol) to a 250ml three-necked flask, 50ml water, 0.15g ammonium metavanadate, heat up to 100°C, add 38.8g (0.4mol) of 65% nitric acid dropwise, After 1 hour of dripping, keep reflux for 4 hours to cool to room temperature; use 30% potassium hydroxide aqueous solution to neutralize to pH = 1.8, evaporate about 50g of water under reduced pressure, and extract three times with cyclohexanone, the amount of cyclohexanone used each time The aqueous phase was extracted into 50 ml, and then the cyclohexanone was distilled off to obtain 8.97 g of 5-methylpyrazine-2-carboxylic acid. The liquid chromatography analysis was 99.5%, and the yield was 65%.

Embodiment 3

[0048] Embodiment 3 carries out following processing step in sequence:

[0049] Add 12.4g 2-methyl-5-hydroxymethylpyrazine (0.1mol) to a 250ml three-necked flask, 50ml water, 0.15g sodium metavanadate, heat up to 100°C, add 58.2g (0.6mol) of 65% nitric acid dropwise, After 1 hour of dripping, keep reflux for 8 hours; cool to room temperature, neutralize to PH=1.5 with saturated aqueous sodium carbonate solution, evaporate about 50g of water under reduced pressure, extract the water phase with 50ml×3 ethyl acetate, and then evaporate Ethyl acetate was used to obtain 10.76 g of 5-methylpyrazine-2-carboxylic acid, the liquid chromatography analysis was 99.4%, and the yield was 78%.

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Abstract

The invention relates to a method for synthesizing 5-methylpyrazine-2-carboxylic acid. According to the invention, 2-methyl-5-hydroxymethylpyrazine is used as a raw material, nitric acid is employed as an oxidant, and ammonium metavanadate or sodium metavanadate is employed as a catalyst. Hydroxymethyl is oxidized by the nitric acid to synthesize the 5-methylpyrazine-2-carboxylic acid, so that products have good selectivity and high yield. Moreover, the price of nitric acid is low, and tail gas that is produced during the process of synthesizing the 5-methylpyrazine-2-carboxylic acid by the method can be absorbed by alkali lye to synthesize nitrite or nitrate. Because the ammonium metavanadate or the sodium metavanadate is employed as the catalyst, the reaction temperature for oxidizing the 2-methyl-5-hydroxymethylpyrazine by the nitric acid directly can be reduced; meanwhile, the reaction rate can be enhanced, and side reaction can be reduced. Furthermore, tail gas NO2 produced by the technology in the invention can be absorbed by the alkali lye, so that environmental pollution can be reduced.

Description

technical field [0001] The invention relates to a method for synthesizing 5-methylpyrazine-2-carboxylic acid. technical background [0002] 5-Methylpyrazine-2-carboxylic acid is a key intermediate for the preparation of drugs glipizide and acipimus. The current synthetic methods mainly contain the following synthetic methods: [0003] 1. Using 2,5-dimethylpyrazine as the starting material, the nitric oxide intermediate is prepared by hydrogen peroxide oxidation, and then esterified with acetic anhydride, then hydrolyzed by sodium hydroxide and oxidized by potassium permanganate to prepare 5-methylpyrazine Pyrazine-2-carboxylic acid, the process uses potassium permanganate, will produce a lot of MnO 2 Solid waste, and the yield is very low (J. Org. Chem. 26, 126 (1961). [0004] 2. O-phenylenediamine and methylglyoxal method [0005] CN1392143 obtains 3-methylbenzopyrazine by cyclization of o-phenylenediamine and aceguv aldehyde, then uses potassium permanganate to oxidize...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D241/24B01J27/24B01J23/22
Inventor 王健黄林
Owner 自贡市华气化学制品有限公司
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