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Method for purifying piperidine

A technology of hexahydropyridine and potassium hydroxide, applied in the direction of organic chemistry, etc., can solve problems such as low yield, limited use of hexahydropyridine, complicated process, etc.

Inactive Publication Date: 2010-04-21
北京益利精细化学品有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0002] Hexahydropyridine is a widely used chemical raw material, which can be used as a solvent, an intermediate in organic synthesis, an epoxy resin crosslinking agent, a condensation catalyst, and as a nucleophile in cationic polymerization. However, existing The hexahydropyridine, that is, piperidine, comes from the hydrogenation reduction of pyridine under the action of a catalyst, which contains many impurities such as water, carbon dioxide and unreduced substances. The existence of these impurities greatly limits the performance of hexahydropyridine. use
[0003] There are also some purification methods for hexahydropyridine in the prior art, but these methods are either complicated in process, or the purity of the obtained hexahydropyridine is not high, and the yield is low, so it is difficult to meet the requirements of economy and quality at the same time
For example, the method of dehydrating and distilling calcium oxide, the method adopts the method of adding a certain amount of small block calcium oxide in the distillation kettle for dehydration, and then steams hexahydropyridine through distillation, and the calcium hydroxide powder that absorbs water remains In the tower kettle, the disadvantage is that the dispersion of calcium hydroxide in hexahydropyridine is not good, so that a large amount of hexahydropyridine is mixed with powdered calcium hydroxide and cannot be evaporated, which reduces the yield
In addition, a large amount of solid waste is generated during the purification process, and it is difficult and impossible to discharge these solid waste during operation

Method used

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  • Method for purifying piperidine
  • Method for purifying piperidine

Examples

Experimental program
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Effect test

Embodiment 1

[0016] Add 500 grams of sodium hydroxide to 200 kg of crude hexahydropyridine under stirring conditions, keep the temperature at 20-30°C, continue stirring for 24 hours, and then let the resulting mixture stand for 8 hours to separate into layers; (2 ) Distillation: add the supernatant liquid obtained after stratification in step (1) to an inclined orifice rectification tower with 24 trays for rectification, control the temperature below 106°C to distill out residual water, and then the temperature The temperature is raised to 106°C, and the finished product is received until the temperature has a rising trend, and the heating and distillation are stopped to obtain hexahydropyridine with a purity of 99.8% and a yield of 85%. According to Karl Fischer method, the impurity moisture content is less than 0.1%.

Embodiment 2

[0017] Example 2: The same process conditions as in Example 1 were used, except that 500 g of flake potassium hydroxide was used instead of 500 g of granular sodium hydroxide in Example 1. Hexahydropyridine with a purity of 99.8% was obtained, and the yield was 86%. According to Karl Fischer method, the impurity moisture content is below 0.1%.

Embodiment 3

[0018] Example 3: The same process conditions as in Example 1 were used, except that 500 grams of molten sodium hydroxide was used instead of the powdered sodium hydroxide in Example 1. Hexahydropyridine with a purity of 99.8% was obtained, and the yield was 88%. Analyzed by Karl Fischer method, the impurity water content is less than 0.1%.

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Abstract

The invention provides a method for purifying piperidine. The method comprises the following steps: (1) adding solid base to crude piperidine under a stirring condition, holding temperature between 20 and 30 DEG C, continuously stirring for more than 24 hours and then standing obtained mixture liquid for 6 to 10 hours to layer the mixture liquid; and (2) performing rectification, namely adding supernatant obtained after demixing in a step (1) to a rectification column for rectification to obtain piperidine with the purity of 99.8 percent. The method has the advantages of simple process, low cost, high yield and high purity of the obtained piperidine.

Description

Technical field [0001] The invention relates to a method for purifying hexahydropyridine, in particular to a method for purifying hexahydropyridine by an alkaline method. Background technique [0002] Hexahydropyridine is a widely used chemical raw material. It can be used as a solvent, organic synthesis intermediate, epoxy resin crosslinking agent, condensation catalyst, and as a nucleophile in cationic polymerization reactions. However, the existing The hexahydropyridine or piperidine is derived from the hydrogenation reduction of pyridine under the action of a catalyst. It contains many impurities such as water, carbon dioxide and unreduced substances. The existence of these impurities greatly limits the hexahydropyridine use. [0003] There are also some purification methods for hexahydropyridine in the prior art, but these methods are either complicated in process, or the purity of the obtained hexahydropyridine is not high, the yield is low, and it is difficult to meet the r...

Claims

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Application Information

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IPC IPC(8): C07D295/027C07D295/023
Inventor 刘殿莹郭存林赵玉峰杨秀玉
Owner 北京益利精细化学品有限公司