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Method for preparing 5-methylprazine-2-carboxylic acid

A technology of methyl pyrazine and pyrazine dicarboxylic acid, applied in chemical instruments and methods, organic decomposition, organic chemistry and other directions, can solve the problems of high temperature, unfavorable large-scale production, harsh conditions, etc., and achieves high selectivity, green The effect of mild environmental conditions and few by-products

Active Publication Date: 2009-09-02
LIAONING ASYMCHEM LAB CO LTD
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This method has harsh conditions, although it is a water phase reaction, but the temperature is high, which is not conducive to large-scale production

Method used

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  • Method for preparing 5-methylprazine-2-carboxylic acid
  • Method for preparing 5-methylprazine-2-carboxylic acid

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0019] Add 80g 5-methyl-2,3-pyrazine dicarboxylic acid to a 2L four-neck bottle (1eq) and 0.96kg saturated saline (10ml / g), heated to 110oC and refluxed for 10h. When the reaction proceeds to the HPLC showing 91% conversion rate, it is cooled to room temperature, filtered with suction, and the filtrate is filtered with 1.6kg methyl ethyl ketone (25mL / g), the organic phases are combined and concentrated, cooled in an ice-water bath to crystallize, and filtered with suction to obtain the product 33.5g. HPLC purity: 98%, isomer impurity content: 1.1%, yield: 55%.

Embodiment 2

[0021] Add 36g 5-methyl-2,3-pyrazine dicarboxylic acid to a 2L four-neck bottle (1eq) and 349g saturated brine (8ml / g), heated to 108oC and refluxed for 8h. When the reaction proceeds to HPLC showing 92% conversion rate, it is cooled to room temperature, filtered with suction, and the filtrate is filtered with 524g methyl ethyl ketone (18mL / g). The organic phases are combined and concentrated, cooled in an ice-water bath to crystallize, and filtered with suction to obtain the product 15.3 g. HPLC purity: 98%, isomer impurity content: 0.7%, yield: 56.2%.

Embodiment 3

[0023] Add 54g 5-methyl-2,3-pyrazine dicarboxylic acid to a 2L four-neck bottle (1eq) and 327g saturated brine (5ml / g), heated to 105oC and refluxed for 8h. When the reaction proceeds to HPLC showing 90% conversion rate, it is cooled to room temperature, filtered with suction, the filtrate is combined with 655g methyl ethyl ketone (15mL / g), the organic phases are combined and concentrated, cooled and crystallized in an ice-water bath, and filtered with suction to obtain the product 22.5 g. HPLC purity: 98%, isomer impurity content: 2.0%, yield: 55%.

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Abstract

The invention provides a method for preparing 5-methylprazine-2-carboxylic acid. The preparation method comprises the steps: using 5-methyl-2and3- pyrazine 2-carboxylic acid as raw material, carrying out photophobism reaction in a saturated saline solution, and obtaining 5-methylprazine-2-carboxylic acid as a final product. The preparation method optimizes the process from the source on the basis of the principle of water decarboxylation, thereby being a method for effective decarboxylation in a saline solution at lower temperature. Moreover, in the preparation method, no organic solvent is added in the chemical reaction, no pollution is generated, the condition is mild, the reaction in the whole technological process has no high temperature, high selectivity and few by-products, thus the preparation method is a simple and available pollution-free method which has the capability of large-scale production.

Description

(1) Technical field: [0001] The invention relates to a preparation method of 5-methylpyrazine-2-carboxylic acid. (2) Background technology: [0002] The decarboxylation reaction generally takes advantage of the instability of the compound to heat, and is completed by methods such as vacuum decarboxylation, solvent decarboxylation, and high pressure decarboxylation in an aqueous medium. [0003] Vacuum decarboxylation is the use of vacuum to remove the carbon dioxide generated after the reaction, so that the reaction proceeds in the positive direction. This method needs to be equipped with special equipment, and the early production investment is relatively large. [0004] Solvent decarboxylation is to select solvents with higher boiling points, such as xylene and trimethylbenzene, to perform decarboxylation at about 140-180°C. The disadvantage of this method is that the cost is relatively high, a large amount of organic solvents are consumed, the by-products are large and difficu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D241/24C07B37/06
Inventor 洪浩陈迥陈朝勇
Owner LIAONING ASYMCHEM LAB CO LTD
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