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Method for purifying 2-pyrrolidone

The technology of a pyrrolidone and a purification method, which is applied in the field of medicine and chemical industry, can solve the problems of low crystallization temperature, requirements, and the content cannot meet the requirements for use, and achieves the effects of low energy consumption and simple process

Inactive Publication Date: 2017-02-22
JIAOZUO ZHONGWEI CHEM
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

At present, the manufacturer adopts the traditional batch distillation method. Although this method can also achieve the purpose, it needs multiple distillations. Since 2-pyrrolidone is a heat-sensitive substance, it consumes a lot of energy, and some 2-pyrrolidones are damaged due to repeated heating. (mainly caused by intramolecular condensation), which affects the yield, and at the same time the content is difficult to meet the requirements
[0003] The melting point of 2-pyrrolidone is 24.5°C. If crystallization and purification are simply based on this melting point, there will be the following defects: (1) The crystallization speed is slow and cannot be applied to large-scale production; (2) The crystallization temperature is low, requiring a refrigeration device, increasing Energy consumption; (3) Some impurities will crystallize together with the product, and the content does not meet the requirements for use

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0012] Get transition fraction 1000 grams, use Agilent chromatograph, SE-54 capillary column analysis is as follows: NVP accounts for 15%, 2-pyrrolidone accounts for 75%, other impurity accounts for 10%. Add 159 grams of water, place it in a deep well water bath at 18°C, stir, and after 30 minutes, add a little seed crystal when the temperature reaches 24°C, crystallization will occur soon, and centrifuge after it becomes viscous to obtain 650 grams crystal, the rest is mother liquor, and the purity of the crystal is 99.58%. The mother liquor can also be recrystallized, and the crystal purity can reach 98.2% after centrifugation. After the primary crystal is melted, it can be directly used as the raw material for the production of NVP, and the secondary crystal needs to be crystallized again before it can be used as the raw material for the production of NVP.

Embodiment 2

[0014] After taking 1000 grams of cuts, the chromatographic analysis contained 73% of 2-pyrrolidone, 2.6% of NVP, and the rest were impurities. Add 155 grams of water, place it in a deep well water bath at 18°C, stir, and after 30 minutes, add a little seed crystal when the temperature reaches 24°C, crystallization will occur soon, and centrifuge after it becomes viscous to obtain 610 grams crystal, the rest is mother liquor, and the purity of the crystal is 99.53%. The mother liquor can also be recrystallized, and the crystal purity can reach 97.8% after centrifugation. After the primary crystallization, it can be directly used as the raw material for the production of NVP, and the secondary crystal needs to be crystallized again before it can be used as the raw material for the production of NVP.

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Abstract

The invention discloses a method for purifying 2-pyrrolidone. The method comprises the steps of mixing impure 2-pyrrolidone with water, carrying out crystallization at the temperature of 15 DEG C to 28 DEG C, and carrying out solid-liquid separation, thereby obtaining high-purity 2-pyrrolidone and mother liquor. Compared with the prior art, the method has the advantages that the process is simple, the energy consumption is low, and crystallized crystals are loose and cannot form lumpy cake shapes, so that subsequent centrifuging and sweating operations are facilitated; and the purity of the high-purity 2-pyrrolidone reaches 99.5% or more.

Description

technical field [0001] The invention belongs to the field of medicine and chemical industry, in particular to a method for purifying 2-pyrrolidone. Background technique [0002] N-vinylpyrrolidone (hereinafter referred to as NVP) is a very useful pharmaceutical intermediate. At present, the main preparation method is to use acetylene and 2-pyrrolidone at a certain pressure and temperature, and use potassium hydroxide as a catalyst. Since the conversion rate of 2-pyrrolidone is only 50-65%, there is still 35-50% of 2-pyrrolidone not converted, and there are 5-15% other impurities in addition. The impurity in this part is mainly due to the self-aggregation of the generated NVP or the low selectivity. NVP is used to prepare PVP series products after purification, and 2-pyrrolidone is used as a raw material for the synthesis of NVP after purification. In the separation process of NVP and 2-pyrrolidone, the cuts of the following components can be produced: 1, the transition cut...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): C07D207/26
CPCC07D207/26
Inventor 张恒家
Owner JIAOZUO ZHONGWEI CHEM
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