Preparation method of 4,6-dichloropyrimidine

A technology of dichloropyrimidine and dihydroxypyrimidine, which is applied in the field of preparation of organic compounds, can solve the problems of increased material consumption, low recovery rate, and energy consumption, so as to reduce material and energy consumption, facilitate industrial scale-up production, and avoid product loss Effect

Inactive Publication Date: 2012-10-24
CHONGQING UNISPLENDOUR CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

But above-mentioned method has the following problems in actual production: 1) reclaim excessive phosphorus oxychloride to carry out under higher vacuum degree, and recovery rate is low (sometimes less than 35%), not only expends a large amount of energy, but also increases Material consumption; 2) The operations of organic solvent extraction, drying and dehydration, and recovery of organic solvents are cumbersome and time-consuming. Organic solvents are toxic to a certain extent, causin

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0011] In a four-neck flask equipped with a reflux condenser, a thermometer, a stirrer, and a constant pressure dropping funnel, add 4,6-dihydroxypyrimidine (22.8g, content 98%, 0.2mol) and phosphorus oxychloride (62.3 g, content 99%, 0.402mol), add triethylamine (40.8g, content 99%, 0.4mol) dropwise between temperature control 50-65°C, heat up to 120°C after addition, keep stirring for 2 hours, analyze by HPLC The 4,6-dihydroxypyrimidine content was 0.5%, the 4,6-dichloropyrimidine content was 98.8%, and the reaction was completed. Cool the reaction mixture to 25°C, add dropwise sodium hydroxide solution with a mass fraction of 50% between 25-30°C to pH = 6, then conduct steam distillation, collect the distillate, filter with suction, and dry the filter cake , 27.9 g of 4,6-dichloropyrimidine (white solid) was obtained, the HPLC analysis content was 99.6%, and the yield was 93.9%.

Embodiment 2

[0013] In a four-neck flask equipped with a reflux condenser, a thermometer, a stirrer, and a constant pressure dropping funnel, add 4,6-dihydroxypyrimidine (22.8g, content 98%, 0.2mol) and phosphorus oxychloride (62.3 g, content 99%, 0.402mol), add triethylamine (40.8g, content 99%, 0.4mol) dropwise between temperature control 50-65°C, heat up to 120°C after addition, keep stirring for 2 hours, analyze by HPLC The 4,6-dihydroxypyrimidine content was 0.5%, the 4,6-dichloropyrimidine content was 98.8%, and the reaction was completed. Cool the reaction mixture to 25°C, add dropwise sodium hydroxide solution with a mass fraction of 50% between 25-30°C to pH = 6.5, then conduct steam distillation, collect the distillate, filter with suction, and dry the filter cake , 27.7 g of 4,6-dichloropyrimidine (white solid) was obtained, the HPLC analysis content was 99.6%, and the yield was 92.6%.

Embodiment 3

[0015] In a four-neck flask equipped with a reflux condenser, a thermometer, a stirrer, and a constant pressure dropping funnel, add 4,6-dihydroxypyrimidine (22.8g, content 98%, 0.2mol) and phosphorus oxychloride (62.3 g, content 99%, 0.402mol), add triethylamine (40.8g, content 99%, 0.4mol) dropwise between temperature control 40-45°C, heat up to 120°C after addition, keep stirring for 2 hours, analyze by HPLC The 4,6-dihydroxypyrimidine content was 0.3%, the 4,6-dichloropyrimidine content was 99.5%, and the reaction was completed. Cool the reaction mixture to 10°C, add dropwise sodium hydroxide solution with a mass fraction of 50% between 10-20°C to pH = 6, then conduct steam distillation, collect the distillate, filter with suction, and dry the filter cake , 27.5 g of 4,6-dichloropyrimidine (white solid) was obtained, the HPLC analysis content was 99.1%, and the yield was 91.5%.

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Abstract

The invention discloses a preparation method of 4,6-dichloropyrimidine, which comprises the following steps: mixing 4,6-dihydroxypyrimidine and phosphorus oxychloride, dropwise adding triethylamine under the temperature of 40-65 DEG C, then heating up to 110-120 DEG C, carrying out heat preservation reaction, stopping the reaction until the content of 4,6-dihydroxypyrimidine is less than 1%, cooling reaction mixture to below 30 DEG C, dropwise adding sodium hydroxide solution while controlling the temperature not more than 30 DEG C until the pH is in the range of 6-6.5, conducting steam distillation, collecting distillate, separating solid and liquid, and drying solid to obtain the 4,6-dichloropyrimidine; The invention uses stoichiometric or slight excess of phosphorus oxychloride. There is no need to recover phosphorus oxychloride after the reaction. Material and energy consumption and loss of product are reduced. Separation methods such as organic solvent extraction, drying and dehydration, organic solvent recovering and the like are not used. There is no need to use and recover organic solvent. The preparation method provided by the invention is environment friendly, avoids loss of product, produces no extra solid waste, and is conducive to industrial scale production. The product has high yield and purity, and can reach the commercial requirement without being subjected to secondary purification. The production cycle is short and the production cost is low.

Description

technical field [0001] The invention belongs to the field of organic chemistry and relates to a preparation method of a class of organic compounds. Background technique [0002] 4,6-Dichloropyrimidine is an important intermediate in the synthesis of sulfa drugs and fungicide azoxystrobin. There are many reports in the literature about its preparation method. One of the preparation methods is to react 4,6-dihydroxypyrimidine with triethylamine and excess phosphorus oxychloride at a certain temperature, and the resulting reaction mixture is distilled under reduced pressure to recover the excess phosphorus oxychloride, and poured into ice water. Extract with an organic solvent, dry and dehydrate, and recover the organic solvent to obtain 4,6-dichloropyrimidine. But above-mentioned method has the following problems in actual production: 1) reclaim excessive phosphorus oxychloride to carry out under higher vacuum degree, and recovery rate is low (sometimes less than 35%), not o...

Claims

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Application Information

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IPC IPC(8): C07D239/30
Inventor 丁永良龙晓钦曹超周红朱丽利
Owner CHONGQING UNISPLENDOUR CHEM
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