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Preparation method of halohydrocarbon-free alpha-cyanoacrylate

A technology of cyanoacrylate and cyanoacetate is applied in the field of preparation of high-purity α-cyanoacrylate, and can solve the problems of poor control of synthesis temperature, difficulty in chemical production and conversion, unstable vacuum degree, etc. The reaction is easy to control, not easy to hydrolyze, and the effect of improving product purity

Active Publication Date: 2014-02-12
山东禹王和天下新材料有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Although this method solves the potential safety hazard caused by the toxicity of organic solvents, in actual operation, the control of the degree of vacuum in the condensation reaction is not easy to operate, especially in the initial stage of the condensation reaction, due to the vacuum state, it is easy to charge the material, resulting in poor control of the reaction; And as the air pressure in the reactor is unstable, the vacuum degree is also unstable, which eventually leads to poor control of the synthesis temperature and difficulty in chemical production and conversion.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0028] 1. Applied to the preparation of ethyl α-cyanoacrylate

[0029] (1) Mix 1500mL ethyl cyanoacetate and 1000mL dimethyl carbonate in the reactor, and at the same time mix 1200g liquid formaldehyde and 10mL hexahydropyridine in the feeding funnel, when the temperature of the material in the reactor reaches 40-45°C, Add 1 / 2 of the mixture of formaldehyde and hexahydropyridine, and start adding the remaining 1 / 2 of the material dropwise when the temperature in the kettle rises to 74°C, and turn on the cooling water to control the temperature in the reactor not to exceed 78°C. After the feeding is completed, the temperature is controlled at 78 °C and the reflux condensation reaction is continued under normal pressure. After the condensation reaction is completed, 5000 ml of dimethyl carbonate is added for dehydration. After the dehydration is complete, 30 g of phosphorus pentoxide and 20 g of hydroquinone polymerization inhibitor are added. Then cracking distillation is carri...

Embodiment 2

[0033] (1) Mix 1600ml of isopropyl cyanoacetate and 1100mL of dimethyl carbonate in the reaction kettle, and at the same time mix 1200mL of formaldehyde and 10mL of triethanolamine in the addition funnel, and add the mixture of formaldehyde and triethanolamine into the reaction kettle twice The timing of the first feeding is when the temperature of the material in the reactor reaches 40-45°C, add 1 / 2 of the mixture of formaldehyde and triethanolamine, and start to drop the remaining 1 / 2 of the mixture when the temperature in the kettle rises to 74°C. For the material, turn on the cooling water to control the temperature in the reactor not to exceed 78°C. After the feeding is completed, the temperature is controlled at 78°C and the reflux condensation reaction is continued under normal pressure. After the condensation reaction is completed, 5500mL of dimethyl carbonate is added for dehydration. Add phosphorus pentoxide in the amount of 4g / mol liquid formaldehyde, and add catecho...

Embodiment 3

[0037] (1) Mix 1600mL of methoxyethyl cyanoacetate and 1200mL of dimethyl carbonate in a reaction kettle, and at the same time, mix liquid formaldehyde (1200g) and sodium hydroxide (10g) in an addition funnel, and mix liquid formaldehyde with hydrogen Add the mixture of sodium oxide to the reaction kettle twice, and the timing of the first feeding is when the temperature of the material in the reaction kettle reaches 40-45°C, add 1 / 2 of the mixture of formaldehyde and sodium hydroxide, and wait until the temperature in the kettle rises to 74 At ℃, start to drop the remaining 1 / 2 of the material, turn on the cooling water to control the temperature in the reactor not to exceed 78 ℃, after the feeding is completed, the temperature is controlled at 78 ℃ and the reflux condensation reaction is continued under normal pressure, after the condensation reaction is completed, add 5400mL Dimethyl carbonate is dehydrated, and after the dehydration is complete, p-tert-butylphenol polymeriz...

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Abstract

The invention relates to a preparation method of halohydrocarbon-free alpha-cyanoacrylate, which comprises the following steps: mixing cyanoacetate and methyl carbonate in a reaction kettle, simultaneously mixing formaldehyde and a base catalyst in a charging hopper, then adding the mixture of the formaldehyde and the base catalyst to the reaction kettle at twice, performing a refluxing and condensation reaction at 78 DEG C under normal pressure, adding a dehydration solvent methyl carbonate to dehydrolyze after the condensation reaction is finished, adding an anionic polymerization inhibitor phosphorus pentoxide and a free radical polymerization inhibitor, and depolymerizing and distilling at 155-210 DEG C at a vacuum degree of 0.5-30 mmHg to obtain an alpha-cyanoacrylate coarse monomer; and rectifying the coarse monomer to obtain a high-purity alpha-cyanoacrylate refined monomer, wherein the yield of the alpha-cyanoacrylate refined monomer is more than 75%, and the purity of the alpha-cyanoacrylate refined monomer is 99%. The invention has the advantages of no pollution, energy conservation and high yield and high purity of the obtained product, and is stable in reaction, thereby being suitable for popularization and application.

Description

technical field [0001] The invention relates to a preparation method of α-cyanoacrylate, in particular to a preparation method of high-purity α-cyanoacrylate without using halogenated hydrocarbon as a dehydrating agent. Background technique [0002] At present, the main production process or method of α-cyanoacrylate is: alkyl cyanoacetate (ethyl cyanoacetate, butyl cyanoacetate, etc. are commonly used depending on the product series) in aqueous formaldehyde or more After POM is mixed, condensation reaction is carried out in the presence of basic catalyst (usually hexahydropyridine, sodium hydroxide, sodium alkoxide, etc.), and dehydrating agent is added after the condensation reaction. The dehydrating agent does not participate in the condensation reaction, and the dehydration is recovered after dehydration After adding the plasticizer, carry out cracking distillation at a certain temperature and polymerization inhibitor to obtain the crude monomer of α-cyanoacrylate (such ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C255/23C07C253/30
Inventor 刘锡潜刘锡鼎万鹏曾军王淑敏
Owner 山东禹王和天下新材料有限公司
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