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Preparation method of alpha-cyanoacrylate

A technology of cyanoacrylate and cyanoacetate is applied in the field of preparation of α-cyanoacrylate and can solve the problems of low product yield and purity.

Active Publication Date: 2019-05-28
HEBEI CHENGXIN
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0004] Aiming at the problem that the yield and purity of the product obtained in the preparation method of the existing α-cyanoacrylate is relatively low when preparing α-cyanoacrylate long-chain esters or alkoxy esters, the present invention provides an α-cyanoacrylate preparation method

Method used

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  • Preparation method of alpha-cyanoacrylate

Examples

Experimental program
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Effect test

Embodiment 1

[0055] The preparation method of α-ethyl cyanoacrylate monomer:

[0056] ①Mix 300g of ethyl cyanoacetate and solid formaldehyde or formaldehyde solution in dichloroethane or toluene medium, add hexahydropyridine catalyst, control the temperature at 70°C±5°C, and carry out condensation reaction for 2 hours to obtain α-cyanide Oligomers of ethyl acrylate;

[0057] Wherein the feeding amount of ethyl cyanoacetate and formaldehyde aqueous solution (calculated as formaldehyde) is 1.02:1.00, and the addition amount of hexahydropyridine is 0.15% of the weight percentage of ethyl cyanoacetate.

[0058] ②Add 50g of dioctyl phthalate to the oligomer of α-ethyl cyanoacrylate, remove the solvent under normal pressure or reduced pressure until the temperature of the kettle is 140°C, add 8g of phosphorus pentoxide, terephthalate Phenol 4g, cracked under reduced pressure at -0.098Mpa, collected fractions at 150-200°C, and obtained 290g of crude monomer of ethyl α-cyanoacrylate;

[0059] ③T...

Embodiment 2

[0062] The preparation method of n-butyl α-cyanoacrylate:

[0063] Get 500g of the α-ethyl cyanoacrylate monomer prepared in Example 1 and add in a 1000ml flask, add 1% chloroacetic acid, 0.3% hydroquinone and 0.33% concentrated sulfuric acid, add 444g n-butanol, stir Raise the temperature, control the temperature of the kettle to 100-115°C, collect the ethanol fraction at the top of the tower at 76-82°C; Pressure (200-800Pa) to collect fractions with a content > 98% until the temperature at the top of the column drops significantly. 425 g of n-butyl α-cyanoacrylate with a content >99% were obtained.

[0064] Among the present invention, select glacial acetic acid or anhydrous phosphoric acid as the anionic polymerization inhibitor, select methanesulfonic acid or p-toluenesulfonic acid to replace chloroacetic acid and the concentrated sulfuric acid in the present embodiment as the catalyst, as long as the consumption of the anionic polymerization inhibitor is 1-2% of the mol...

Embodiment 3

[0066] The preparation method of n-butyl α-cyanoacrylate:

[0067] Take 500 g of the α-ethyl cyanoacrylate monomer prepared in Example 1 and add it to a 1000 ml flask, add 2% of a mixture of glacial acetic acid and anhydrous phosphoric acid (the molar ratio of glacial acetic acid and anhydrous phosphoric acid is 0.7:1), The mixture of 0.35% hydroquinone and 0.45% concentrated sulfuric acid and p-toluenesulfonic acid (the mol ratio of concentrated sulfuric acid and p-toluenesulfonic acid is 1:1), add 444g n-butanol, stir and heat up, control the temperature of the kettle at 100 -115°C, collect the ethanol fraction at the top of the tower at 76-82°C; increase the temperature of the kettle to 120-140°C, collect n-butanol under normal pressure and water pump decompression (-0.1MPa), and depressurize the oil pump (200-800Pa) Fractions containing >98% were collected until the overhead temperature dropped significantly. 440 g of n-butyl α-cyanoacrylate with a content >99% was obtain...

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Abstract

The invention relates to a preparation method of alpha-cyanoacrylate. The preparation method mainly includes the following steps that methyl cyanoacetate or ethyl cyanoacetate and formaldehyde are subjected to a condensation reaction to obtain a cyanoacrylate prepolymer; the cyanoacrylate prepolymer is cracked and rectified to obtain a methyl cyanoacrylate monomer or an ethyl cyanoacrylate monomer; and an anionic polymerization inhibitor, a free radical polymerization inhibitor, a catalyst and alcohol are added to the methyl cyanoacrylate monomer or the ethyl cyanoacrylate monomer for an esterexchange reaction, and the alpha-cyanoacrylate is obtained. According to the preparation method of the alpha-cyanoacrylate, the long-chain alpha-cyanoacrylate with the high content can be directly prepared, the depolymerization process under high-temperature and high-vacuum conditions is not required, the cost is lowered, the yield of products is increased, and the purity and stability of the products are improved.

Description

technical field [0001] The invention relates to the technical field of adhesives, in particular to a preparation method of α-cyanoacrylate. Background technique [0002] α-cyanoacrylate adhesive has the characteristics of fast curing, wide range of bonding materials, thin adhesive layer, good transparency, and convenient use, so it has been widely used in daily life and industrial adhesives. α-cyanoacrylate adhesive was first synthesized by German chemist Addis, and the production process that has been industrialized is based on Knoevenagel Condensation. The main process is: α-cyanoacrylate Acrylic acid ester and formaldehyde are condensed into a long-chain prepolymer under alkaline conditions, the reaction is terminated with acid, the solvent is removed, and then cracked under reduced pressure in the presence of a polymerization inhibitor to obtain a crude product, and finally the crude product is refined to obtain the product. The process has been well optimized in the pr...

Claims

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Application Information

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IPC IPC(8): C07C255/23C07C253/30C07C253/34
Inventor 王虹李成果张朝纯范春艳孙洁浩刘少军董津
Owner HEBEI CHENGXIN
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