Process for preparing pyrazine-2-formic acid through metalloporphyrin catalytic oxidation of 2-methylpyrazine

Abstract

The invention relates to a process for preparing pyrazine-2-formic acid through metalloporphyrin catalytic oxidation of 2-methylpyrazine. The process comprises the steps of using 2-methylpyrazine as raw materials; using a mixed solution of ethanol or 60% - 90% (by volume) of ethanol and water as a solvent; using monokaryon metalloporphyrin having a structure represented by formula (I) or formula (II) or dicaryon metalloporphyrin having a structure represented by formula (III) as a catalytic agent with the using amount accounting for 0.02% - 0.07% of raw material weight; reacting for 0.5 - 8 hours at a temperature between 80 DEG C - 140 DEG C under the oxygen pressure of 0.5 - 2.5 MPa in the presence of alkali sodium hydroxide or potassium hydroxide; subjecting the reacted product to acidification, filtration, extraction and hot water recrystallization; and obtaining the pyrazine-2-formic acid finally. According to the process, a small amount of the catalytic agent is consumed and the catalytic agent does not require to be separated, the reaction temperature is low, the solvent environment is friendly, and the process has wide application prospects in industry.

Description

technical field [0001] The invention relates to a method for preparing pyrazine-2-carboxylic acid by catalyzing the oxidation of 2-methylpyrazine by metalloporphyrin. Background technique [0002] Pyrazine-2-carboxylic acid is an important pharmaceutical intermediate, mainly used in the synthesis of the anticancer drug oltipraz and the first-line anti-tuberculosis drug pyrazinamide. At the same time, it is also a widely used bridging ligand. At present, the preparation methods of pyrazine-2-carboxylic acid mainly include chemical oxidation method, intermolecular ring method, decarboxylation method and hydrolysis method. The preparation of pyrazine-2-carboxylic acid by air or oxygen oxidation of 2-methylpyrazine has the advantages of short process, simple operation, readily available raw materials, simple separation, etc. Compared with other synthetic methods, it has broader industrial application prospects. [0003] US 3154549 (publication date: October 27, 1964) discloses...

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Problems solved by technology

[0006] (1) It is usually necessary to use chemical oxidants, which are generally expensive and used in large quantities, and a large amount of toxic waste water and waste liquid are generated during the preparation process, which pollutes the environment;

[0007] (2) It generally needs to be reacted at high temperature (225°C), which increases energy consumption and equipment cost, and increases the risk of operation;

[0008] (3) Catalyst consumption is big (weight ratio 2~3%), also must be separated after using, has increased the input of equipment cost;

[0009] (4) The use of non-environmentally friendly solvents (1,2-dimethoxyethane) increases environmental pollution

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