Malononitrile purification method

A purification method, malononitrile technology, applied in the purification/separation of carboxylic acid nitrile, organic chemistry, etc., can solve the problems affecting the quality and efficacy of pyrimidinamine, high steam energy consumption, affecting yield, etc., so as to save the need for regular cleaning work, avoid environmental pollution, and reduce the effect of refining costs

Active Publication Date: 2021-04-20
HEBEI CHENGXIN +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This will inevitably cause the solvent to be discharged through the exhaust port of the vacuum pump, resulting in organic gas pollution and waste of solvent.
At the same time, due to the high boiling point of malononitrile, even in the case of high vacuum, the initial temperature of the extracted malononitrile fraction is above 100°C, which consumes a lot of energy for steam.
And because the melting point of malononitrile is only 32-34°C, during the high vacuum vacuum distillation process, malononitrile gas will inevitably be sucked into the vacuum pump, causing blockage of the vacuum pump, which needs to be cleaned regularly
In addition, since the malononitrile crude product contains unreacted cya

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0027] A method for purifying malononitrile, comprising the following processing steps:

[0028] a. Weigh 700.3kg of malononitrile synthesis product in the precipitation kettle, start heating and carry out atmospheric distillation precipitation, stop distillation after heating to 110°C, obtain 371.2kg of fractions, 328.8kg of still material (malononitrile crude product) . Wherein, the synthetic product of malononitrile is obtained through amide dehydration reaction using cyanoacetamide as raw material and ethylene dichloride as solvent under the action of quaternary ammonium salt and calcium chloride.

[0029] b. At 15°C, make the kettle material 0.3m 3 The rate of / h enters the first-stage melting crystallizer with an inner diameter of the tube of 50 mm, and the uncrystallized liquid flows out from the outlet at the same time. After the feeding of the kettle material is completed, the remaining liquid is blown out with nitrogen, and the remaining solid crystal is heated to ...

Embodiment 2

[0033] A method for purifying malononitrile, comprising the following processing steps:

[0034] a. Weigh 750kg of the malononitrile synthesis product in the precipitation kettle, start heating for atmospheric distillation and precipitation, stop the distillation after heating to 85°C, and obtain 391.6kg of distillates and 358.0kg of kettle material. Wherein, the synthetic product of malononitrile is obtained by amide dehydration reaction using cyanoacetamide as raw material and ethylene dichloride as solvent under the action of quaternary ammonium salt and phosphorus pentoxide.

[0035] b. At 16°C, make the kettle material 0.2m 3 / h enters the first-stage melting crystallizer with an inner diameter of 50 mm, while the uncrystallized liquid flows out from the outlet. After the feeding of the kettle material is completed, the remaining liquid is blown out with nitrogen, and the remaining solid crystal is heated to 55°C to melt to obtain a molten crystal product;

[0036] c. A...

Embodiment 3

[0038] A method for purifying malononitrile, comprising the following processing steps:

[0039] a. Weigh 730kg of malononitrile synthesis product in a precipitation kettle, start heating to carry out atmospheric distillation precipitation, stop the distillation after heating to 120°C, obtain 374.3kg of fractions, and 355.5kg of kettle material. Wherein, the synthetic product of malononitrile is obtained through amide dehydration reaction using cyanoacetamide as raw material and ethylene dichloride as solvent under the action of quaternary ammonium salt and calcium chloride.

[0040] b. At 17°C, make the kettle material 0.5m 3 / h enters the first-stage melting crystallizer with an inner diameter of 50 mm, while the uncrystallized liquid flows out from the outlet. After the feeding of the kettle material is completed, the remaining liquid is blown out with nitrogen, and the remaining solid crystal is heated to 60°C to melt to obtain a molten crystal product;

[0041] c. At 37...

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PUM

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Abstract

The invention relates to the technical field of compound purification, and particularly discloses a malononitrile purification method. The purification method of malononitrile specifically comprises the step of separating malononitrile from a malononitrile crude product through adoption of a melt crystallization method. According to the malononitrile purification method provided by the invention, a vacuum system does not need to be arranged, the required temperature is relatively low, the energy consumption is reduced by 50% or above, the refining cost and refining time of malononitrile are greatly reduced, and the finally obtained malononitrile pure product has extremely high purity and yield.

Description

technical field [0001] The invention relates to the technical field of compound purification, in particular to a method for purifying malononitrile. Background technique [0002] Malononitrile is an important pesticide and pharmaceutical intermediate. In terms of pesticides, malononitrile can be used to prepare 2-amino-4,6-dimethoxypyrimidine, and then used to produce sulfonylurea herbicides such as bensulfuron-methyl, pyrazosulfuron-methyl, etc., and bispyribac Class herbicides. In terms of medicine, malononitrile can be used to synthesize a series of important drugs such as vitamin B1, aminopterin, and triamterene. At the same time, malononitrile can also be used as an extraction agent for gold. [0003] At present, the purification process of the malononitrile crude product synthesized by cyanoacetamide is usually carried out by atmospheric pressure precipitation and then vacuum distillation. However, in actual operation, the solvent and malononitrile cannot be comple...

Claims

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Application Information

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IPC IPC(8): C07C253/34C07C255/04
Inventor 李晓俊张林杰李娟张国栋宋香哲张影赵欢温明军李成果
Owner HEBEI CHENGXIN
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