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Preparation method of alpha-cyanacrylate for controlling powder size of paraformaldehyde

A technology of cyanoacrylate and alkyl cyanoacrylate, which is applied in the field of preparation of α-alkyl cyanoacrylate, can solve the problems of decreased yield of main reaction, low product purity, slow condensation reaction rate, etc. , achieve the effects of reduced condensation reaction time, wide application prospects, and obvious economic benefits

Inactive Publication Date: 2009-07-08
北京科化新材料科技有限公司
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] The shortcoming of above-mentioned known technology is that when carrying out condensation reaction, because the particle size of the paraformaldehyde of one of raw materials used is too big (≥ 1mm), cause condensation reaction rate to be too slow so that reaction time is longer, easily make too much in the reactor The hydrolysis of the polymer increases the side reaction, resulting in a decrease in the yield of the main reaction and a low purity of the product

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0017] The preparation of embodiment 1.α-ethyl cyanoacrylate

[0018] (1). Mix ethyl cyanoacetate and paraformaldehyde (with a particle size of 40-100 mesh) in a reactor, and react in the presence of a hexahydropyridine catalyst at a temperature of 60±5°C without a dehydrating agent. The initial temperature is 35mmHg, and the condensation reaction is carried out under 1-3mmHg vacuum at the end of the reaction. After the dehydration is complete, add phosphorus pentoxide and hydroquinone polymerization inhibitor, and then in a vacuum with a vacuum degree of 1-5mmHg and a temperature of 160-195°C Carry out cracking distillation under the condition of;

[0019] Wherein, the feeding molar ratio of ethyl cyanoacetate and paraformaldehyde is 1.05:1.00; the addition amount of phosphorus pentoxide is 5 g / mol paraformaldehyde, and the addition amount of hydroquinone is 2 g / mol paraformaldehyde; The addition amount of hexahydropyridine is 3ml / mol paraformaldehyde.

[0020] (2). The cru...

Embodiment 2

[0021] The preparation of embodiment 2.α-methoxy ethyl cyanoacrylate

[0022] (1). Mix methoxyethyl cyanoacetate and paraformaldehyde (with a particle size of 40 to 100 mesh) in a reaction kettle, and in the presence of a hexahydropyridine catalyst, in the absence of a dehydrating agent, the temperature is 60 ± 5 ℃ and 30mmHg at the beginning of the reaction, and the condensation reaction is carried out under 1mmHg vacuum at the end of the reaction. After the dehydration is complete, add phosphorus pentoxide and hydroquinone polymerization inhibitor, and then in a vacuum with a vacuum degree of 0.1-25mmHg and a temperature of 160-200 Cracking distillation is carried out under the condition of ℃;

[0023] Among them, the molar ratio of methoxyethyl cyanoacetate to paraformaldehyde is 1.05:1.00; the addition amount of phosphorus pentoxide is 5g / mol paraformaldehyde, and the addition amount of hydroquinone is more than 2g / mol Paraformaldehyde; the addition amount of hexahydropyr...

Embodiment 3

[0026] (1). Mix methyl cyanoacetate and paraformaldehyde (60-120 mesh particle size) in a reaction kettle, add toluene solvent under normal pressure in the presence of sodium hydroxide catalyst, and add toluene solvent at a temperature of 100°C Carry out condensation reaction; after dehydration is complete, add phosphorus pentoxide, catechol and p-tert-butylphenol polymerization inhibitor, recover the dehydrating agent toluene and then put it in a vacuum with a vacuum degree of 0.5-25mmHg and a temperature of 160-190°C Cracking distillation under conditions;

[0027] Wherein, the molar ratio of methyl cyanoacetate and paraformaldehyde is 1.05:1.00; the addition of phosphorus pentoxide is 4g / mol paraformaldehyde, and the addition of catechol and p-tert-butylphenol are respectively 1g / mol paraformaldehyde; the addition amount of sodium hydroxide is 1.0-1.5g / mol paraformaldehyde, and the addition amount of dehydration solvent toluene is 30-40ml / mol paraformaldehyde.

[0028] (2)...

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Abstract

The invention relates to an alpha-cyanacrylate preparing method of controlling cavaform powder size in the alpha-cyanacrylate adhesive agent field. which comprises the following steps: regarding cyanoacetate and 40-120 powder size as the material; proceeding with the condensation reaction with lower boiling organic solvent which can azeotropy with water as the anhydrating agent at 60-100Deg. C and atmosphere pressure or without anhydrating agent at 60+-5Deg. C, 0.5-50mmHg vacuum condition; adding the inhibitor after completing dewatering; proceeding with cracking distillation at 0.1-25mmHg vacuum and 160-220Deg. C; getting high purity and production efficient alpha-cyanacrylate by distillation. The invention is provided with the wide application foreground and the apparent economy benefit in the industry preparing of alpha-cyanacrylate product series.

Description

technical field [0001] The invention belongs to the field of alpha-cyanoacrylate adhesives, in particular to a preparation method of alpha-cyanoacrylate alkyl for controlling the particle size of paraformaldehyde powder. Background technique [0002] U.S. Patents 3254111, 3639361, 3577394, and Chinese Patent Publication Nos. CN87103468, CN1261070, CN1070636, and CN1047077 all disclose the synthesis process or method for preparing α-cyanoacrylate (mainly α-alkyl cyanoacrylate). The main method of the currently known process is briefly described as follows: after mixing alkyl cyanoacetate (commonly used ethyl cyanoacetate, butyl cyanoacetate, etc. depending on the product series) with paraformaldehyde, in alkali Condensation reaction is carried out in the presence of a neutral catalyst (usually pyridine, sodium hydroxide, sodium alkoxide, etc.) and a dehydrating agent, the dehydrating agent is recovered after dehydration, and depolymerization distillation is carried out at a c...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C07C253/30C07C255/23
Inventor 袁有学任惠敏李琦冉建新
Owner 北京科化新材料科技有限公司