CN112679385B - Purification method of malononitrile - Google Patents
Purification method of malononitrile Download PDFInfo
- Publication number
- CN112679385B CN112679385B CN202011631767.6A CN202011631767A CN112679385B CN 112679385 B CN112679385 B CN 112679385B CN 202011631767 A CN202011631767 A CN 202011631767A CN 112679385 B CN112679385 B CN 112679385B
- Authority
- CN
- China
- Prior art keywords
- malononitrile
- product
- melt
- crystallization
- crude
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Active
Links
Landscapes
- Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
Abstract
The invention relates to the technical field of compound purification, and particularly discloses a method for purifying malononitrile. The purification method of the malononitrile is characterized in that the malononitrile is separated from crude malononitrile by a melting crystallization method. The purification method of the malononitrile provided by the invention does not need to be provided with a vacuum system, the required temperature is lower, the energy consumption is reduced by more than 50%, the refining cost and the refining time of the malononitrile are greatly reduced, and the finally obtained pure malononitrile has extremely high purity and yield.
Description
Technical Field
The invention relates to the technical field of compound purification, in particular to a method for purifying malononitrile.
Background
Malononitrile is an important intermediate of pesticide and medicine. In the aspect of pesticides, malononitrile can be used for preparing 2-amino-4, 6-dimethoxypyrimidine, and further used for producing sulfonylurea herbicides such as bensulfuron-methyl, pyrazosulfuron-ethyl and the like, and bispyribac-sodium herbicides. In the aspect of medicine, malononitrile can be used for synthesizing a series of important medicines such as vitamin B1, aminopterin, triamterene and the like. Meanwhile, the malononitrile can also be used as an extractant of gold.
The purification process of the crude malononitrile synthesized by cyanoacetamide at present usually adopts a mode of desolventizing at normal pressure and then rectifying under reduced pressure. However, in actual practice, the solvent and malononitrile cannot be completely separated by the desolvation under normal pressure, and the solvent needs to be further distilled under reduced pressure to completely remove the solvent, and then the malononitrile is extracted by the distillation under high vacuum and reduced pressure. Therefore, the solvent is exhausted through the exhaust port of the vacuum pump, and further organic gas pollution and waste of the solvent are caused. Meanwhile, because the boiling point of the malononitrile is high, even under the condition of high vacuum, the initial temperature of the extracted malononitrile fraction is over 100 ℃, and the energy consumption on steam is high. And the melting point of the malononitrile is only 32-34 ℃, so that the malononitrile gas is inevitably pumped into a vacuum pump in the high-vacuum reduced-pressure distillation process to cause the blockage of the vacuum pump, and the malononitrile gas needs to be cleaned regularly. In addition, because the crude malononitrile contains unreacted cyanoacetamide and high-boiling point substances, the rectification method can only achieve about 99.5%, and if the purity of the malononitrile is high and reaches more than 99.9%, re-rectification or increase of reflux ratio during rectification is needed. In this case, the malononitrile is exposed to a high temperature for a long time, and thus a part of the malononitrile is polymerized, which seriously affects the yield.
Part of the downstream products of malononitrile, such as pyrimidinamine, have high requirements on the content of malononitrile, and a small amount of impurities in malononitrile can also seriously affect the quality and efficacy of the finally synthesized pyrimidinamine.
Disclosure of Invention
Aiming at the problems of the existing purification method of malononitrile, the invention provides a purification method of malononitrile, which can obviously improve the yield and the purity of malononitrile.
In order to achieve the purpose of the invention, the embodiment of the invention adopts the following technical scheme:
a method for purifying malononitrile by separating the malononitrile from crude malononitrile by melt crystallization.
The method for purifying the malononitrile provided by the invention separates the malononitrile from the crude malononitrile by a melt crystallization method, has no requirement on vacuum degree compared with the traditional rectification purification method, does not need to purchase a vacuum pump, has lower required temperature, avoids environmental pollution caused by large volatilization of a solvent, does not need to worry about vacuum pump blockage caused by the malononitrile, and saves the regular cleaning work of equipment. Meanwhile, compared with a rectification purification method, the method for purifying malononitrile has the advantages that the energy consumption is reduced by more than 50%, and the refining cost of malononitrile is greatly reduced. More unexpectedly, the purification method provided by the invention enables the obtained pure malononitrile product to have high yield and high purity, the purity of the pure malononitrile product can reach more than 99.95%, and the yield can reach more than 99%.
Preferably, the crude malononitrile is obtained by taking cyanoacetamide as a raw material and performing amide dehydration reaction and normal pressure desolventizing under the action of a solvent, a catalyst and a dehydrating agent. Wherein the solvent is dichloroethane, toluene or dichloromethane, the catalyst is a quaternary ammonium salt catalyst, and the dehydrating agent is conventional dehydrating agents such as calcium chloride, phosphorus pentoxide and the like.
Preferably, the final temperature of the normal pressure desolventizing is 85-120 ℃.
Preferably, the purification method of malononitrile comprises the following process steps:
a. crystallizing the crude malononitrile at 0-25 ℃, blowing out the liquid which is not crystallized by inert gas, and heating and melting the solid crystal to obtain a melt crystal product;
b. crystallizing the melt crystallization product at 30-50 ℃, blowing out the uncrystallized liquid by inert gas, and collecting the liquid to obtain the pure malononitrile.
By continuously carrying out twice melt crystallization at a specific temperature, a large amount of impurities in the malononitrile and the crude malononitrile can be quickly separated by the first crystallization, and a small amount of impurities in the melt crystallization product obtained by the first crystallization can be quickly crystallized and separated from the malononitrile in the melt crystallization product by the second crystallization; the process can not only reduce the temperature and energy consumption in the purification process, but also avoid polymerization of the malononitrile, and further improve the purity and yield of the pure malononitrile.
Preferably, in step a, the specific method for crystallizing the crude malononitrile comprises the following steps: the crude malononitrile is added with the weight of 0.2-0.5m 3 The crystallization is carried out at a rate of/h in a melt crystallizer with a 50mm internal diameter of the tube array.
The crude malononitrile product is added by 0.2-0.5m 3 The crystallization is carried out in the melting crystallizer with the inner diameter of a 50mm tube array at the speed of/h, the crystallization efficiency and the crystal purity can be improved, meanwhile, the liquid which is not crystallized can be blown out by inert gas immediately after the crude malononitrile product is fed into the melting crystallizer at the speed of/h, the retention is not needed, and the purification time is obviously shortened.
Preferably, in step a, the crystallization temperature of the crude malononitrile is 15-17 ℃. At this crystallization temperature, the crystallization efficiency of malononitrile can be further improved.
Preferably, in step a, the temperature for melting by raising the temperature is 30-100 ℃.
Preferably, in the step a, the temperature for increasing the temperature and melting is 50-60 ℃.
The heating melting temperature can ensure that the malononitrile is completely melted and can save a large amount of energy consumption.
Preferably, in step b, the specific method for crystallizing the melt crystallization product is as follows: the melt-crystallized product is added at a ratio of 0.2-0.5m 3 The crystallization is carried out at a rate of/h in a melt crystallizer with a 50mm internal diameter of the tube array.
The melt-crystallized product is added in an amount of 0.2 to 0.5m 3 The crystallization is carried out in the melting crystallizer with the inner diameter of a 50mm tube array at the speed of/h, the separation efficiency of a malononitrile melting crystallization product and impurities can be improved, meanwhile, the liquid which is not crystallized can be blown out by inert gas immediately after the crude malononitrile enters the melting crystallizer at the speed of/h, the retention is not needed, and the purification time and the purity of the malononitrile in the blown liquid are obviously shortened.
Preferably, in step b, the temperature at which the melt crystallization product is crystallized is 32 to 37 ℃. At the crystallization temperature, the purity of the pure malononitrile can be further improved.
Preferably, in step a and step b, the inert gas is nitrogen or helium.
Detailed Description
In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is further described in detail with reference to the following embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.
Example 1
A method for purifying malononitrile, which comprises the following process steps:
a. 700.3kg of malononitrile synthesis product is weighed in a desolventizing kettle, heating is started to carry out normal pressure distillation desolventizing, and distillation is stopped after the heating is carried out to 110 ℃, so that 371.2kg of fraction and 328.8kg of kettle material (crude malononitrile) are obtained. Wherein, the malononitrile synthesis product is obtained by taking cyanoacetamide as a raw material and dichloroethane as a solvent through amide dehydration reaction under the action of quaternary ammonium salt and calcium chloride.
b. The pot charge was brought to 0.3m at 15 ℃ 3 The flow rate/h was fed into a primary melt crystallizer with a tube array having an internal diameter of 50mm, while the uncrystallized liquid flowed out through the outlet. After the kettle material is fed, blowing out the residual liquid by using nitrogen, and heating the residual solid crystal to 50 ℃ for melting to obtain a molten crystal product;
c. the melt-crystallized product was brought to 0.3m at 32 DEG C 3 The flow rate/h was fed into a secondary melt crystallizer having a tube array with an internal diameter of 50mm, while the uncrystallized liquid flowed out through the outlet. And after the molten and crystallized product is fed, blowing out the residual liquid by using nitrogen, and collecting the liquid flowing out of the outlet and the blown-out liquid, namely the pure malononitrile product, so as to obtain 298.8kg of the pure malononitrile product. The detection proves that the mass content of the malononitrile in the pure product of the malononitrile is 99.97%, and the yield of the malononitrile is 99.31%.
Wherein, the yield of the malononitrile is the mass content of the malononitrile in the pure product of the malononitrile/the mass content of the malononitrile in the product synthesized by the malononitrile.
Example 2
A method for purifying malononitrile comprises the following process steps:
a. 750kg of malononitrile synthesis product is weighed in a desolventizing kettle, heating is started to carry out normal pressure distillation desolventizing, and distillation is stopped after the heating is carried out to 85 ℃, so that 391.6kg of fraction and 358.0kg of kettle material are obtained. Wherein, the malononitrile synthetic product is obtained by taking cyanoacetamide as a raw material and dichloroethane as a solvent through amide dehydration reaction under the action of quaternary ammonium salt and phosphorus pentoxide.
b. The pot charge was brought to 0.2m at 16 ℃ 3 The flow/h is directed into a primary melt crystallizer with a tube array having an internal diameter of 50mm, while the uncrystallized liquid flows out through an outlet. After the kettle material is fed, blowing out the residual liquid by using nitrogen, and heating the residual solid crystal to 55 ℃ for melting to obtain a molten crystal product;
c. the melt-crystallized product was brought to 0.2m at 35 deg.C 3 The flow rate/h was fed into a secondary melt crystallizer having a tube array with an internal diameter of 50mm, while the uncrystallized liquid flowed out through the outlet. And after the feeding of the melt crystallization product is finished, blowing out the residual liquid by using nitrogen, and collecting the liquid flowing out of the outlet and the blown-out liquid, namely the pure malononitrile product to obtain 307.1kg of the pure malononitrile product. The detection proves that the mass content of the malononitrile in the pure product of the malononitrile is 99.98 percent, and the yield of the malononitrile is 99.30 percent.
Example 3
A method for purifying malononitrile comprises the following process steps:
a. 730kg of malononitrile synthesis product is weighed into a desolventizing kettle, heating is started to carry out normal pressure distillation desolventizing, and distillation is stopped after the heating is carried out to 120 ℃, so that 374.3kg of fraction and 355.5kg of kettle material are obtained. Wherein, the malononitrile synthesis product is obtained by taking cyanoacetamide as a raw material and dichloroethane as a solvent through amide dehydration reaction under the action of quaternary ammonium salt and calcium chloride.
b. The pot charge was brought to 0.5m at 17 ℃ 3 The flow/h is directed into a primary melt crystallizer with a tube array having an internal diameter of 50mm, while the uncrystallized liquid flows out through an outlet. After the kettle material is fed, blowing out the residual liquid by using nitrogen, and heating the residual solid crystals to 60 ℃ for melting to obtain a molten crystal product;
c. the melt-crystallized product was brought to 0.5m at 37 deg.C 3 The velocity of the flow is such that the flow is directed into a secondary melt crystallizer having a tube array with an internal diameter of 50mm, while the uncrystallized liquid is discharged through an outlet. And after the molten and crystallized product is fed, blowing out the residual liquid by using nitrogen, and collecting the liquid flowing out of the outlet and the blown-out liquid, namely the pure malononitrile product, so as to obtain 303.9kg of the pure malononitrile product. The detected purity of malononitrileThe mass content of malononitrile in the product is 99.98%, and the yield of malononitrile is 99.25%.
Example 4
A method for purifying malononitrile, which comprises the following process steps:
a. weighing 700kg of malononitrile synthesis product into a desolventizing kettle, starting heating to perform normal pressure distillation desolventizing, stopping distillation after heating to 110 ℃, and obtaining 374.1kg of fraction and 325.4kg of kettle material. Wherein, the malononitrile synthetic product is obtained by taking cyanoacetamide as a raw material and dichloroethane as a solvent through amide dehydration reaction under the action of quaternary ammonium salt and calcium chloride.
b. The pot charge was brought to 0.4m at 0 deg.C 3 The flow/h is directed into a primary melt crystallizer with a tube array having an internal diameter of 50mm, while the uncrystallized liquid flows out through an outlet. After the kettle material is fed, blowing out the residual liquid by using nitrogen, and heating the residual solid crystal to 30 ℃ for melting to obtain a molten crystal product;
c. the melt-crystallized product was brought to 0.4m at 30 ℃ 3 The flow rate/h was fed into a secondary melt crystallizer having a tube array with an internal diameter of 50mm, while the uncrystallized liquid flowed out through the outlet. And after the molten and crystallized product is fed, blowing out the residual liquid by using nitrogen, and collecting the liquid flowing out of the outlet and the blown-out liquid, namely the pure malononitrile product, so as to obtain 297.2kg of the pure malononitrile product. The detection proves that the mass content of the malononitrile in the pure product of the malononitrile is 99.96 percent, and the yield of the malononitrile is 99.33 percent.
Example 5
A method for purifying malononitrile comprises the following process steps:
a. weighing 700kg of malononitrile synthesis product in a desolventizing kettle, starting heating for atmospheric distillation desolventizing, stopping distillation after heating to 110 ℃, obtaining 375.8kg of fraction and 324.0kg of kettle material. Wherein, the malononitrile synthetic product is obtained by taking cyanoacetamide as a raw material and dichloroethane as a solvent through amide dehydration reaction under the action of quaternary ammonium salt and calcium chloride.
b. At 25 deg.C, the pot charge was brought to 0.4m 3 H into a primary melt crystallizer with a tube array having an internal diameter of 50mm, while the uncrystallized liquid flows out of the outletAnd (6) discharging. After the kettle material is fed, blowing out the residual liquid by using nitrogen, and heating the residual solid crystal to 100 ℃ for melting to obtain a molten crystal product;
c. the melt-crystallized product was brought to 0.4m at 50 deg.C 3 The velocity of the flow is such that the flow is directed into a secondary melt crystallizer having a tube array with an internal diameter of 50mm, while the uncrystallized liquid is discharged through an outlet. And after the molten and crystallized product is fed, blowing out the residual liquid by using nitrogen, and collecting the liquid flowing out of the outlet and the blown-out liquid, namely the pure malononitrile product, so as to obtain 295.3kg of the pure malononitrile product. The detection proves that the mass content of the malononitrile in the pure product of the malononitrile is 99.97%, and the yield of the malononitrile is 99.18%.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents or improvements made within the spirit and principle of the present invention should be included in the scope of the present invention.
Claims (3)
1. A method for purifying malononitrile, which is characterized in that: separating the malononitrile from the crude malononitrile by melt crystallization; the method comprises the following process steps:
a. crystallizing the crude malononitrile at 0-17 ℃, blowing out the liquid which is not crystallized by inert gas, and heating the solid crystal to 50-100 ℃ for melting to obtain a melt crystal product;
b. crystallizing the melt crystallization product at 32-37 ℃, blowing out the uncrystallized liquid by using inert gas, and collecting the liquid to obtain a pure malononitrile product; in the step a, the specific method for crystallizing the crude malononitrile comprises the following steps: the crude malononitrile product is added by 0.2-0.5m 3 The crystallization is carried out in a melt crystallizer with the inner diameter of a 50mm row pipe at the speed of/h; in the step b, the specific method for crystallizing the melt crystallization product comprises the following steps: feeding the melt crystallization product into a melt crystallizer with the inner diameter of a 50mm array pipe at the speed of 0.2-0.5m3/h for crystallization;
the crude malononitrile is obtained by taking cyanoacetamide as a raw material and performing amide dehydration reaction and normal pressure desolventizing under the action of a solvent, a catalyst and a dehydrating agent.
2. The method of purifying malononitrile according to claim 1, wherein: the final temperature of the normal pressure desolventizing is 85-120 ℃.
3. The process for purifying malononitrile according to claim 1, wherein: in step a and step b, the inert gas is nitrogen or helium.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011631767.6A CN112679385B (en) | 2020-12-31 | 2020-12-31 | Purification method of malononitrile |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN202011631767.6A CN112679385B (en) | 2020-12-31 | 2020-12-31 | Purification method of malononitrile |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN112679385A CN112679385A (en) | 2021-04-20 |
| CN112679385B true CN112679385B (en) | 2022-09-09 |
Family
ID=75456064
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN202011631767.6A Active CN112679385B (en) | 2020-12-31 | 2020-12-31 | Purification method of malononitrile |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN112679385B (en) |
Family Cites Families (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE1201325B (en) * | 1963-11-25 | 1965-09-23 | Knapsack Ag | Process for the continuous production of malonic dinitrile |
| DE2260126C2 (en) * | 1972-12-08 | 1983-12-01 | Degussa Ag, 6000 Frankfurt | Process for the production of pure, stable malononitrile |
| CN1079094C (en) * | 1998-10-09 | 2002-02-13 | 如东县通园精细化工厂 | Process for preparing high-purity malononitrile |
| CN104945278A (en) * | 2015-06-04 | 2015-09-30 | 荆州和乐实业科技有限公司 | Malononitrile synthesis method |
| EP3173402B1 (en) * | 2015-11-30 | 2018-03-21 | Evonik Degussa GmbH | Fine purification of isophorone nitrile by melt crystallization |
| CN107721878A (en) * | 2017-10-23 | 2018-02-23 | 天津大学 | A kind of method using fusion-crystallization technology separating-purifying succinonitrile |
| CN107827777B (en) * | 2017-10-27 | 2020-09-11 | 河北诚信集团有限公司 | Synthesis method of malononitrile |
| CN110156632A (en) * | 2019-05-29 | 2019-08-23 | 南通市纳百园化工有限公司 | A kind of separating and extracting process of malononitrile |
-
2020
- 2020-12-31 CN CN202011631767.6A patent/CN112679385B/en active Active
Also Published As
| Publication number | Publication date |
|---|---|
| CN112679385A (en) | 2021-04-20 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CN100354266C (en) | Prep. of epsilon-hexanolactam | |
| US10294197B2 (en) | Purifying method, production method, and distillation apparatus for acrylonitrile | |
| CN108409658B (en) | High-efficiency refining method of caprolactam | |
| US2436311A (en) | Preparation of n, n'ethyleneurea | |
| CN112679385B (en) | Purification method of malononitrile | |
| US5696305A (en) | Process for the production of nitroaromatic compounds | |
| CN110128285B (en) | Preparation method of D-phenylglycine methyl ester hydrochloride/D-dihydrophenylglycine methyl ester hydrochloride | |
| CN115231989B (en) | Preparation method of 3, 5-dichlorobenzyl alcohol | |
| CN110066249B (en) | Novel caprolactam refining and purifying method | |
| KR20190080535A (en) | Process for the purification of laurolactam and purifing apparatus thereof | |
| CN114174258A (en) | Recovery of anhydrous methanesulfonic acid from a distillation column bottom stream | |
| US4178448A (en) | Process for preparing herbicidal triazines | |
| CN112094203B (en) | Preparation method of 1-cyano-2-propenyl acetate | |
| CN111592492A (en) | Method for improving quality of caprolactam product subjected to liquid phase Beckmann rearrangement | |
| JPH01261363A (en) | Production of high-purity caprolactam | |
| US4195032A (en) | Process for continuously working up solutions of the type accumulating in the phosgenation of monoamines | |
| CN115443263A (en) | Process for acylating alpha, omega-alkanediols | |
| US3966786A (en) | Method for producing chloroformates | |
| CN111153833A (en) | Method and device for extracting biuret from reaction liquid of urea and polyol | |
| CN113880776B (en) | Preparation method of rituximab intermediate | |
| CN110950919B (en) | Synthetic method of sofosbuvir | |
| US3562254A (en) | Production of caprolactam starting with cyclohexanone | |
| CN117229266B (en) | Method for synthesizing ramosetron racemate and salt thereof | |
| US2447419A (en) | Preparation of diphenylacetonitrile | |
| US4066691A (en) | Process for the production of pure diglycolic acid by oxidation of diethylene glycol with nitric acid |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| TA01 | Transfer of patent application right |
Effective date of registration: 20220818 Address after: 051130 south of dongyuanzhao highway, Yuanshi railway station, Shijiazhuang City, Hebei Province Applicant after: HEBEI CHENGXIN Co.,Ltd. Applicant after: HEBEI CHENGXIN JIUTIAN PHARMACEUTICAL CHEMICAL CO.,LTD. Address before: 051130 south of dongyuanzhao highway, Yuanshi railway station, Shijiazhuang City, Hebei Province Applicant before: HEBEI CHENGXIN Co.,Ltd. |
|
| TA01 | Transfer of patent application right | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |