The preparation method of triazine ring

Abstract

The invention belongs to the technical field of organic intermediate preparation, and in particular relates to a preparation method of a triazine ring. The method comprises the following steps: adding 2-methylthiosemicarbazide, diethyl oxalate and mixed alcohol solvent into the reaction bottle, adding a mixed alkali catalyst dropwise, carrying out ring closure reaction at 45-55°C, acidifying with hydrochloric acid, cooling to 0-5°C and pumping Filter to obtain the crude triazine ring; dissolve the crude triazine ring in distilled water at 65-70°C, cool down to 10-15°C to crystallize to obtain the wet product of the triazine ring, dry at 90-100°C for 3-5 hours, and obtain the triazine ring Dry goods. The preparation method of the present invention does not introduce a new solvent system, and should have high selectivity, less side reactions, easy recovery and treatment of the solvent system, and high product yield; the raw materials used are cheap and easy to obtain, low in cost, and suitable for industrial scale-up.

Description

Technical field [0001] The present invention belongs to the technical field of preparation of organic intermediates, specifically relates to a method of preparation of triazine rings. Background [0002] Triazine ring (TTZ) is a key intermediate in the synthesis of ceftriaxone sodium, which has a wide range of applications in polymer materials, dyes, pesticides, and pharmaceutical industries, and has very important development value. [0003] Molecular formula: C 4 H 5 N 3 O 2 S。 [0004] The structural formula is as follows: [0005] [0006] At present, there are two main preparation methods for triazine rings: [0007] (1) With 2-methylamidourea, diethyl oxalate as raw material, sodium methanol as the catalyst for cyclic reaction, the reaction requires a large number of solvent systems to complete, while the system is very viscous, resulting in uneven local concentration, while sodium methanol alkaline is too strong, in the presence of local excess alkali, the generation of ...

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Problems solved by technology

The route of this process is more complicated, especially the preparation of raw material methylmalonyl chloride is complicated, and the yield is low (about 80%), and it is a highly active acid chloride intermediate, which is inconvenient to operate, and it must use ion exchange resin simultaneously. Purification, complex process, high cost, not suitable for industrial production, no practical production significance

[0009] In order to avoid these two disadvantages, the patent CN 104177305 A proposes the idea of ​​using a mixed solvent, but this invention introduces one of DMF, DMSO, NMP, HMPA, acetone, acetonitrile, dioxane, and THF. None of the solvents are in the reaction system. The biggest disadvantage of the above patents is the introduction of a new solvent system, which increases the difficulty of recycling and introduces new environmental issues.

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