Method for separating 4-cyanopyridine by cooling solvent crystallization

A cyanopyridine and cooling crystallization technology, which is applied in the field of separation and purification of chemical production, can solve the problems of unsatisfactory separation effect of 4-cyanopyridine, fumaric nitrile prone to polymerization reaction, and clogging of rectification device equipment, etc. Good economy, reasonable structure, and the effect of improving productivity

Active Publication Date: 2020-02-04
ANHUI RUIBANG BIOLOGICAL SCI & TECH CO LTD
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  • Claims
  • Application Information

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Problems solved by technology

[0003]4-cyanopyridine is mainly derived from the ammoxidative synthesis of alkylpyridine, but the synthesis of 4-cyanopyridine using alkylpyridine is usually accompanied by 3-cyano Pyridine is generated, in order to obtain the required high-purity intermediate raw material, the crude product of 4-cyanopyridine must be separated and purified, but since 3-cyanopyridine is an isomer of 4-cyanopyridine, 3-cyanopyridine The boiling point difference from 4-cyanopyridine is only 5°C, so it is difficult to separate
[0004] At present, most industrial

Method used

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  • Method for separating 4-cyanopyridine by cooling solvent crystallization

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Experimental program
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Effect test

Embodiment 1

[0024] Such as figure 1 As shown, a 4-cyanopyridine separation and purification device includes a device body 1, a crystallization box 2 and a centrifuge box 3 are arranged inside the device body 1, the crystallization box 2 is fixedly installed above the centrifuge box 3, and the bottom of the centrifuge box 3 is fixed and installed 4. There is a rotating shaft 5 inside the crystallization box 2. The lower end of the rotating shaft 5 is fixed with a stirring rod 6. The upper end of the rotating shaft 5 runs through the middle of the top of the crystallization box 2. The rotating shaft 5 is connected with the crystallization box 2 in a sealed rotation, and the middle of the top of the crystallization box 2 is fixed. Motor one 7 is installed, and the output shaft of rotating shaft 5 tops is connected with motor one 7, and crystallization box 2 top left side is provided with feed inlet 8, and crystallization box 2 top right sides is provided with water inlet 9, and crystallizatio...

Embodiment 2

[0026] A method of using the solvent cooling crystallization of separation and purification device in embodiment 1 to separate 4-cyanopyridine, comprising the following steps:

[0027] S1. Add the crude 4-cyanopyridine to the separation and purification device, add a mixed solvent of ethanol and ether with a volume ratio of 2.5:1 to the separation and purification device, and the mass ratio of the added mixed solvent to the crude 4-cyanopyridine is 1.5: 1. Heat and stir to make a saturated solution of 4-cyanopyridine;

[0028] S2. Cool the saturated 4-cyanopyridine solution prepared in step S1 at a rate of 1.4° C. / min, and 4-cyanopyridine crystals are precipitated to obtain a mixed slurry;

[0029] S3. Centrifugally filter the mixed slurry obtained in step S2 to obtain filter residue 1 and filtrate 1. Clean filter residue 1 with pure water for 1-2 times and then centrifugally filter to obtain filter residue 2 and filtrate 2. Dry filter residue 2 to obtain high-purity 4-cyanop...

Embodiment 3

[0034] A method of using the solvent cooling crystallization of separation and purification device in embodiment 1 to separate 4-cyanopyridine, comprising the following steps:

[0035] S1. Add the crude 4-cyanopyridine to the separation and purification device, add a mixed solvent of ethanol and ether with a volume ratio of 3:1 to the separation and purification device, and the mass ratio of the added mixed solvent to the crude 4-cyanopyridine is 1.5: 1. Heat and stir to make a saturated solution of 4-cyanopyridine;

[0036] S2. Cool the saturated 4-cyanopyridine solution prepared in step S1 at a rate of 1 °C / min, and 4-cyanopyridine crystals are precipitated to obtain a mixed slurry;

[0037] S3. Centrifugally filter the mixed slurry obtained in step S2 to obtain filter residue 1 and filtrate 1. Clean filter residue 1 with pure water for 1-2 times and then centrifugally filter to obtain filter residue 2 and filtrate 2. Dry filter residue 2 to obtain high-purity 4-cyanopyridi...

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Abstract

The invention provides a method for separating 4-cyanopyridine through solvent cooling crystallization. The method comprises the following steps: S1, preparing a 4-cyanopyridine saturated solution; S2, cooling the saturated solution to obtain a mixed slurry; S3, carrying out centrifugal filtration on the mixed slurry, washing with pure water, and carrying out centrifugal filtration and drying to obtain highly-pure 4-cyanopyridine; S4, performing reduced pressure distillation on the obtained filtrate to obtain a solute, heating and decolorizing the solute, and repeating step S1 and step S2 to obtain highly-pure 4-cyanopyridine; and S5, collecting the highly-pure 4-cyanopyridine obtained in step S3 and step S4 to obtain the finished 4-cyanopyridine product. The purity of the 4-cyanopyridineseparated through cooling crystallization is high, and reaches up to 99.54%; the primary filtrate and the washing filtrate are distilled and then purified, so the yield of 4-cyanopyridine is increased, and can reach up to 97.2%; and a separation and purification device for 4-cyanopyridine can complete a series of steps of crystallization, centrifugation, washing, drying and the like in separationand purification of 4-cyanopyridine.

Description

technical field [0001] The invention relates to the technical field of chemical production separation and purification, in particular to a method for separating 4-cyanopyridine by solvent cooling and crystallization. Background technique [0002] 4-cyanopyridine, the molecular formula is C 6 h 4 N 2 , with a molecular weight of 104.11, is a white to pale yellow needle-like crystal with a characteristic odor. Soluble in ethanol, ether and benzene. The main purpose is to be used as intermediate products of medicine and pesticide. [0003] 4-cyanopyridine is mainly derived from the ammoxidative synthesis of alkylpyridine, but the synthesis of 4-cyanopyridine using alkylpyridine is usually accompanied by the formation of 3-cyanopyridine. In order to obtain the required high-purity intermediate raw materials, it is necessary to Separation and purification of crude 4-cyanopyridine, but since 3-cyanopyridine is an isomer of 4-cyanopyridine, the boiling point difference between...

Claims

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Application Information

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IPC IPC(8): C07D213/85B01D3/10B01D9/00B01D11/02B01D33/11
CPCC07D213/85B01D11/02B01D9/00B01D33/11B01D3/10Y02P20/10
Inventor 杨红军袁晓路刘宣平杨竞成夏建荣刘彬
Owner ANHUI RUIBANG BIOLOGICAL SCI & TECH CO LTD
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