Preparation method of 4, 6-dichloropyrimidine

Abstract

The invention discloses a preparation method of 4, 6-dichloropyrimidine, which comprises the following steps: (1) dissolving 4, 6-dihydroxypyrimidine and a catalyst in a polar solvent, and mixing to obtain a mixed solution containing 4, 6-dihydroxypyrimidine; (2) adding chlorine or liquid chlorine into the mixed solution, and reacting to obtain a mixed solution containing 4, 6-dichloropyrimidine;(3) distilling the mixed solution containing 4, 6-dichloropyrimidine to remove the solvent, deacidifying, and distilling to recover byproduct phosphorus oxychloride, thereby obtaining a 4, 6-dichloropyrimidine crude product; (5) carrying out extraction separation on the 4, 6-dichloropyrimidine crude product, carrying out flash evaporation to remove a solvent and leave 4, 6-dichloropyrimidine in awater phase; and cooling and crystallizing the water phase, and carrying out dehydration treatment to obtain the 4, 6-dichloropyrimidine product. According to the method, the low-price easily-available catalyst is adopted, so that the reaction efficiency can be remarkably improved; chlorine / liquid chlorine is used as a chlorinating agent, so that the risk of the process is greatly reduced, and thebyproduct phosphorus oxychloride with high additional value is produced.

Description

technical field [0001] The invention relates to the technical field of organic chemical synthesis, in particular to a 4,6-dichloropyrimidine synthesis technology. Background technique [0002] 4,6-dichloropyrimidine is an important organic chemical intermediate, used in the production of sulfa products in medicine, such as sulfamethazine, sulfamethiadiazole, sulfamotosine, sulfa-6-methyl Oxypyrimidine, etc.; used in the synthesis of methoxyacrylate fungicide azoxystrobin in pesticides. [0003] In the known method for preparing 4,6-dichloropyrimidine, the main method is to react 4,6-dichloropyrimidine, phosphorus oxychloride and an organic base at a certain temperature, and then react the resulting mixture Perform distillation to reclaim phosphorus oxychloride, then extract with organic solvent in ice water, and reclaim the solvent to obtain product 4,6-dichloropyrimidine (Yang Fengke, Hu Zhanlin, Synthesis Research of 4,6-dichloropyrimidine, Applied Chemical Industry, 2012...

AI Technical Summary

Problems solved by technology

The main disadvantage of this method is that it is difficult to recover the organic base in the reaction process, and at the same time, the waste water output is large, the alkali consumption is large, the useful phosphorus resource is seriously wasted, and it is finally converted into low-value phosphate, and the cost of waste water treatment is high.

[0004] In order to solve the above problems, the Chinese patent with publication number CN106187913A discloses a preparation method of 4,6-dichloropyrimidine, which uses phosgene instead of phosphorus oxychloride for chlorination, although this method can solve some problems , but at the same time it also causes problems such as low yield, poor safety, and poor operability in the process of industrialization

[0005] Chinese patent CN105439963B discloses a method of 4,6-dichloropyrimidine, which is similar to the above-mentioned patented method. The chlorination agent uses triphosgene and diphosgene, which also have the problems of potential safety hazards and low yield.

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