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CN-122010774-A - Preparation method of malononitrile

CN122010774ACN 122010774 ACN122010774 ACN 122010774ACN-122010774-A

Abstract

A preparation method of malononitrile, which belongs to the technical field of fine chemical engineering. The preparation method comprises the steps of mixing dimethyl malonate and ammonia water, stirring and reacting at normal temperature and normal pressure, carrying out post-treatment after the stirring and reacting are finished to obtain malonamide solid, dissolving the obtained malonamide in an organic solvent, adding a dehydrating agent, carrying out stirring and reacting at normal pressure, distilling and recovering the organic solvent after the reaction is finished to obtain a malononitrile crude product, rectifying the obtained malononitrile crude product, and collecting fractions to obtain the malononitrile with high purity of more than 99.5 percent of gas chromatography. The method has the advantages of eliminating potential safety hazards and environmental protection pressure, remarkably reducing raw material cost, having the advantages of low equipment requirement, small energy consumption, simple and safe operation, simple process, short process route and environmental protection, generating no large amount of solid waste, being simple and convenient in post-treatment, being easy to meet the requirement of industrialized amplified production, and being capable of meeting the requirement of high-purity raw materials in high-end application fields such as medicines, pesticides and the like.

Inventors

  • ZHANG FENGSHOU
  • Song Juye
  • WANG LUQIAN
  • YANG ZHENG

Assignees

  • 苏州纤美达材料科技有限公司

Dates

Publication Date
20260512
Application Date
20260327

Claims (10)

  1. 1. A preparation method of malononitrile is characterized by comprising the following steps: A) Preparing malondiamide, namely mixing dimethyl malonate with ammonia water, stirring and reacting at normal temperature and normal pressure, controlling the stirring and reacting time, and after the stirring and reacting are finished, carrying out aftertreatment to obtain malondiamide solid; b) Dissolving the malononitrile obtained in the step A) in an organic solvent, adding a dehydrating agent, stirring and reacting at normal pressure, controlling the time and the temperature of stirring and reacting, and distilling and recovering the organic solvent after the reaction is finished to obtain a malononitrile crude product; c) Refining, namely rectifying the crude malononitrile product obtained in the step B), and collecting fractions to obtain the malononitrile with high purity of more than 99.5% of gas chromatographic purity.
  2. 2. The method for producing malononitrile according to claim 1, wherein the ammonia water concentration by mass in the step A) is 20-30%, and the molar ratio of dimethyl malonate to ammonia water is 1..2-6.
  3. 3. The method for producing malononitrile according to claim 2, wherein the molar ratio of dimethyl malonate to aqueous ammonia is 1..3-5.
  4. 4. The method for producing malononitrile according to claim 1, wherein the stirring reaction time is controlled to be 120 to 360 minutes in the step A).
  5. 5. A process for the preparation of malononitrile according to claim 1, characterized in that the work-up in step A) comprises, after the end of the reaction, removing excess ammonia under reduced pressure, followed by sequential cooling, crystallization, filtration and drying.
  6. 6. The method of claim 1, wherein in step B), the organic solvent is one or more of dichloroethane, dichloromethane and chloroform.
  7. 7. The process for producing malononitrile according to claim 1, wherein the dehydrating agent in the step B) is phosgene or solid phosgene, and the molar ratio of malononimide to dehydrating agent is 1.1 to 1.5.
  8. 8. The method for producing malononitrile according to claim 7, wherein the molar ratio of the malononimide to the dehydrating agent is 1.1 to 1.3.
  9. 9. The method for producing malononitrile according to claim 1, wherein the time for controlling the subsequent reaction in the step B) is 240 to 600 minutes, and the temperature is 60 to 90 ℃.
  10. 10. The method for producing malononitrile according to claim 1, wherein the distillation in step C) is a vacuum distillation under a vacuum degree of-0.09 to-0.1 MPa, and the fraction at 105 to 115℃is collected.

Description

Preparation method of malononitrile Technical Field The invention belongs to the technical field of fine chemical engineering, and particularly relates to a preparation method of malononitrile. Background Malononitrile is an important organic synthesis intermediate, and is widely applied to medicines, pesticides and dyes, and is mainly applied to electronic chemicals and new energy materials, and also relates to precious metal extraction and high polymer synthesis. At present, the industrial process for preparing malononitrile is mainly divided into two major categories, namely synthesis and dehydration. The synthesis method is generally prepared by taking acetonitrile and cyanuric chloride, or chloroacetonitrile and hydrogen cyanide, or chloroethane and sodium cyanide as raw materials and reacting in the presence of a catalyst. The method generally uses virulent cyanide or cyanuric chloride, which puts high requirements on production safety and environmental protection, and the reaction conditions are often harsh, and the dehydration method is prepared by taking cyanoacetamide as a raw material and dehydrating under the action of dehydrating agents such as phosphorus oxychloride, phosphorus pentoxide or phosgene. Although the cyanoacetamide route avoids directly using extremely toxic gas, cyanoacetamide is generally prepared by amination of cyanoacetate, cyanogen-containing raw materials can be involved in the production process, and a large amount of phosphorus-containing solid waste can be generated by the traditional dehydrating agent, so that the environmental protection pressure is huge. Technical information related to the preparation method of malononitrile is seen in the published chinese patent literature, and a typical preparation method of malononitrile is disclosed in CN118619847a, which is prepared by one-step catalytic reaction of malonic acid or dimethyl malonate as a raw material with ammonia gas at high temperature and high pressure, i.e. one-step method for direct catalytic amination without intermediate separation. The method has the advantages of easily obtained raw materials, severe reaction conditions, high equipment requirement and high energy consumption, and the specific composite metal oxide catalyst is used, so that the production cost is not reduced and the process is simplified. Therefore, the method has positive significance in exploring the preparation method of the malononitrile with easily obtained raw materials, simple process, mild reaction conditions, environmental friendliness and capability of obtaining the malononitrile with high purity. Disclosure of Invention The invention aims to provide a preparation method of malononitrile, which has the advantages of low-cost and easily-obtained starting raw materials, no damage to environment, mild reaction conditions, high purity of malononitrile obtained by a two-step method of dehydration through amine, low preparation cost, simple operation, safety and environmental protection. The task of the invention is accomplished in such a way that a preparation method of malononitrile comprises the following steps: A) Preparing malondiamide, namely mixing dimethyl malonate with ammonia water, stirring and reacting at normal temperature and normal pressure, controlling the stirring and reacting time, and after the stirring and reacting are finished, carrying out aftertreatment to obtain malondiamide solid; b) Dissolving the malononitrile obtained in the step A) in an organic solvent, adding a dehydrating agent, stirring and reacting at normal pressure, controlling the time and the temperature of stirring and reacting, and distilling and recovering the organic solvent after the reaction is finished to obtain a malononitrile crude product; c) Refining, namely rectifying the crude malononitrile product obtained in the step B), and collecting fractions to obtain the malononitrile with high purity of more than 99.5% of gas chromatographic purity. In a specific embodiment of the invention, the mass concentration of the ammonia water in the step A) is 20-30%, and the molar ratio of the dimethyl malonate to the ammonia water is 1..2-6. In another specific embodiment of the present invention, the molar ratio of dimethyl malonate to aqueous ammonia is 1..3-5. In yet another specific embodiment of the present invention, the controlling the stirring reaction time as described in step a) is controlling the stirring reaction time to 120-360min. In a further embodiment of the invention, the work-up described in step A) comprises, after the end of the reaction, removing excess ammonia under reduced pressure, followed by successive cooling, crystallization, filtration and drying. In still another specific embodiment of the present invention, in step B), the organic solvent is one or more of dichloroethane, dichloromethane and chloroform. In a further specific embodiment of the invention, the organic solvent is dichloroethane. In a further specific emb