阅读说明：本技术 一种n,n’-亚甲基双丙烯酰胺的合成方法 (Synthesis method of N, N' -methylene bisacrylamide ) 是由 王乐佳 张虎寅 孙世良 肖勋文 肖杰 吴乐先 王恒 于 2020-12-24 设计创作，主要内容包括：本发明涉及一种N,N’-亚甲基双丙烯酰胺的合成方法,本发明以丙烯酰胺和多聚甲醛为反应原料,采用负载型杂多酸催化剂与酰胺活化试剂协同催化,制备了N,N’-亚甲基双丙烯酰胺；负载型杂多酸催化剂与酰胺活化试剂的协同使用可在不影响杂多酸催化的情况下,与丙烯酰胺中的羰基相互作用,破坏酰胺键的p-π共轭体系,提高氨基的亲核性,增强氨基与多聚甲醛的反应活性,大大提高该反应的选择性,从而在不添加大量的水作为反应溶剂的情况下实现原料的高效转化,提高反应产率。本发明使用的杂多酸催化剂固相负载,反应均在固体催化剂表面进行,体系中无大量的酸性溶剂存在,在后处理过程中无需加入碱液中和,简化了后处理步骤并减少了废水的排放。(The invention relates to a synthesis method of N, N '-methylene bisacrylamide, which takes acrylamide and paraformaldehyde as reaction raw materials and adopts a supported heteropolyacid catalyst and an amide activating reagent for concerted catalysis to prepare the N, N' -methylene bisacrylamide; the synergistic use of the supported heteropolyacid catalyst and the amide activating reagent can interact with carbonyl in acrylamide under the condition of not influencing the catalysis of heteropolyacid, so that a p-pi conjugated system of an amido bond is damaged, the nucleophilicity of amino is improved, the reaction activity of the amino and paraformaldehyde is enhanced, the selectivity of the reaction is greatly improved, the high-efficiency conversion of raw materials is realized under the condition of not adding a large amount of water as a reaction solvent, and the reaction yield is improved. The heteropolyacid catalyst used in the invention is loaded in a solid phase, the reaction is carried out on the surface of the solid catalyst, a large amount of acid solvent does not exist in the system, alkali liquor is not required to be added for neutralization in the post-treatment process, the post-treatment step is simplified, and the discharge of waste water is reduced.)

1. A method for synthesizing N, N' -methylene bisacrylamide is characterized by comprising the following steps:

(1) putting the solid-phase porous material into a round-bottom flask, adding a heteropoly acid aqueous solution, heating, stirring, refluxing for a period of time, standing, cooling, filtering out the solid-phase porous material, and drying to obtain a supported heteropoly acid catalyst;

(2) taking acrylamide and paraformaldehyde as raw materials, adding a small amount of polymerization inhibitor, reacting under the catalysis of an amide activating reagent and the supported heteropolyacid catalyst prepared in the step (1),

(3) after the reaction in the step (2) is finished, diluting the reaction system by hot water, and filtering the supported heteropolyacid catalyst by gauze; and (3) transferring the obtained filtrate into a crystallization kettle after vacuum concentration, slowly cooling for crystallization, and performing centrifugal separation to obtain an N, N' -methylene bisacrylamide crystal, namely the target product.

2. The method for synthesizing N, N' -methylenebisacrylamide according to claim 1, wherein: in the step (1), the solid phase porous material is selected from one or more of activated carbon, silica and MCM-41 molecular sieve; the heteropoly acid is one or more of phosphotungstic acid, phosphomolybdic acid, cesium phosphotungstate and sodium silicotungstate, and the mass concentration of the heteropoly acid aqueous solution is 5-15%.

3. The method for synthesizing N, N' -methylenebisacrylamide according to claim 2, wherein: in the step (1), the reflux time is 4-6 h, and the cooling and standing time is 12-24 h; the drying temperature is 110-120 ℃, and the drying time is 2-6 h.

4. The method for synthesizing N, N' -methylenebisacrylamide according to claim 1, wherein: the specific steps of the step (2) are as follows: putting the supported heteropolyacid catalyst prepared in the step (1) and an amide activating reagent into a reaction kettle, and adding water as a reaction solvent; then adding the reactants of acrylamide, paraformaldehyde and polymerization inhibitor in proportion, heating the system to the reaction temperature, reacting for a period of time, and continuing to insulate the clinker for a period of time until the reaction is complete after white solids are separated out.

5. The method for synthesizing N, N' -methylenebisacrylamide according to claim 4, wherein: in the step (2), the amide activating reagent is selected from one or two of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, N-hydroxythiosuccinimide and 4-dimethylaminopyridine; the polymerization inhibitor is any one of p-methoxyphenol, p-hydroxyphenol and phenothiazine.

6. The method for synthesizing N, N' -methylenebisacrylamide according to claim 4, wherein: in the step (2), the addition amount of the supported heteropolyacid catalyst is 6-15 wt% of acrylamide.

7. The method for synthesizing N, N' -methylenebisacrylamide according to claim 4, wherein: in the step (2), the molar ratio of the acrylamide to the amide activating reagent is 1: (0.05-0.25), wherein the molar ratio of acrylamide to water is 1: (1.2-3.0), wherein the molar ratio of acrylamide to paraformaldehyde is 1: (0.92-0.98), wherein the molar ratio of acrylamide to polymerization inhibitor is 1: (0.005-0.01).

8. The method for synthesizing N, N' -methylenebisacrylamide according to claim 4, wherein: in the step (2), the reaction temperature is 60-85 ℃, the reaction time is 0.5-3 h, the temperature of the heat preservation clinker is 45-75 ℃, and the time of the heat preservation clinker is 1-4 h.

9. The method for synthesizing N, N' -methylenebisacrylamide according to claim 1, wherein: and (3) adding diluted hot water at the temperature of 50-80 ℃, concentrating the filtrate in vacuum at the vacuum degree of 50-100mmHg at the vacuum concentration temperature of 45-60 ℃, and concentrating the filtrate in vacuum to 1/2-2/3 of the volume of the original filtrate.

10. The method for synthesizing N, N' -methylenebisacrylamide according to claim 9, wherein: in the step (3), the cooling crystallization temperature is 5-10 ℃, and the cooling crystallization time is 12-36 h.

Technical Field

The invention relates to a synthetic method of N, N' -methylene bisacrylamide.

Background

N, N '-methylene bisacrylamide is a fine chemical with wide application, the molecular structure of the N, N' -methylene bisacrylamide contains two polymerizable double bond active groups, the N, N '-methylene bisacrylamide has the characteristic of a cross-linking agent monomer, can be copolymerized with various ethylene monomers, acrylic acid monomers and acrylic monomers to obtain various copolymers, and due to the fact that the N, N' -methylene bisacrylamide has two double bond active groups, the structure of a high molecular chain can be effectively regulated and controlled in the copolymers, and therefore macroscopic physical and chemical properties of materials can be regulated and controlled.

For example, starch and acrylamide can obtain high-performance water-absorbent resin with excellent water absorption by using N, N' -methylene bisacrylamide as a cross-linking agent, and the high-performance water-absorbent resin is widely applied to soil water retention agents; the thickener for pigment printing in all water phase is prepared with N, N' -methylene bisacrylamide, acrylamide, butyl acrylate and other material and is one key assistant for pigment printing in all water phase.

At present, a polymer formed by crosslinking N, N' -methylene bisacrylamide with acrylamide and other active monomers is widely applied to the construction of water conservancy, electric power engineering and underground engineering, and is a waterproof plugging grouting material with the best effect and the most reliable quality; the fracturing fluid and water shutoff agent used in the oil extraction process are very important chemical raw materials in the petroleum and building industries. In recent years, N' -methylene bisacrylamide has polyfunctional group polymerization sites, is also commonly used in the production industries of photosensitive plastics, nylon photosensitive plates, various films and tapes, novel high-grade high-temperature-resistant fireproof glass and the like, and is a multipurpose crosslinking agent and a chemical auxiliary agent with reliable quality. The research on N, N ' -methylene bisacrylamide is mature in foreign countries, the research on application development and preparation methods of the N, N ' -methylene bisacrylamide is limited in China, and many application fields are yet to be further researched and developed, so that the N, N ' -methylene bisacrylamide has greater potential and value.

The existing method for synthesizing N, N' -methylene bisacrylamide is disclosed as follows:

(1) chinese patent No. CN101462979B discloses that N, N' -methylene bisacrylamide is prepared from acrylamide and formaldehyde solution as raw materials and using hydrochloric acid or sulfuric acid as a catalyst. The method uses inorganic acid as catalyst, and improves reaction yield. However, the concentration of the reactants in the system needs to be strictly controlled during the reaction process to avoid the deactivation of the inorganic acid catalyst. Meanwhile, the post-treatment steps of the product are more, the production equipment is more complex, the used formaldehyde solution has stronger volatility, the production environment is not friendly enough in the charging process, and the industrial production has certain limitation.

(2) In 2008, Martin et al reported a method for synthesizing N, N' -methylenebisacrylamide by using acryloyl chloride and methylenediamine in toluene and potassium carbonate as an acid-binding agent in Journal of Controlled Release. The method can carry out reaction in an organic system, the purity of the obtained product is high, and the yield reaches more than 90%. However, the raw material acryloyl chloride is very easy to decompose in water and generate a large amount of hydrogen chloride, so that the operation is difficult to realize; the reaction raw material methylene diamine is expensive, the reaction needs to be carried out under the conditions of low temperature and no water, the reaction environment is harsh, the production cost is high, and no industrial foundation is provided.

(3) In 2009, the catalytic synthesis of N, N' -methylenebisacrylamide by acrylonitrile and formaldehyde using an acidic ionic liquid was reported by zhuangshan, jingdong sheng et al in "applied chemical industry" and "chemical intermediate" respectively. The method uses 1-methyl-3- [ alpha-methyl- (4-sulfonic acid benzyl) ] imidazole bisulfate acidic ionic liquid as a reaction catalyst, the catalytic efficiency is greatly enhanced compared with inorganic acid, the treatment after the reaction is easier, a large amount of alkali liquor is not required to be added for neutralization, and the generation of byproducts is reduced. However, the preparation process of the used acidic ionic liquid is complex, the price is high, the repeated cyclic utilization rate is low, and the industrial application of the acidic ionic liquid is limited.

In conclusion, the N, N' -methylene bisacrylamide used in the prior art generally has the difficulties of high production cost and environmental pollution caused by the production process, and the free formaldehyde content in the product is high.

Disclosure of Invention

The first technical problem to be solved by the present invention is to provide a method for synthesizing N, N' -methylenebisacrylamide, which can reduce reaction temperature, improve yield, and reduce byproduct generation and waste liquid discharge, aiming at the current situation of the prior art.

The second technical problem to be solved by the invention is to provide a method for synthesizing N, N' -methylene-bisacrylamide, which is mild in reaction conditions, easy to control, high in safety, simple in post-treatment, high in product purity and easy for industrial production, aiming at the current situation of the prior art.

The technical scheme adopted by the invention for solving the technical problems is as follows: a method for synthesizing N, N' -methylene bisacrylamide is characterized by comprising the following steps:

(1) putting the solid-phase porous material into a round-bottom flask, adding a heteropoly acid aqueous solution, heating, stirring, refluxing for a period of time, standing, cooling, filtering out the solid-phase porous material, and drying to obtain a supported heteropoly acid catalyst;

(2) taking acrylamide and paraformaldehyde as raw materials, adding a small amount of polymerization inhibitor, reacting under the catalysis of an amide activating reagent and the supported heteropolyacid catalyst prepared in the step (1),

(3) after the reaction in the step (2) is finished, diluting the reaction system by hot water, and filtering the supported heteropolyacid catalyst by gauze; vacuum concentrating the filtrate, transferring to a crystallization kettle, slowly cooling for crystallization, and performing centrifugal separation to obtain N, N' -methylene bisacrylamide crystals, namely the target product; the centrifugal mother liquor contains an amide activating reagent, and can be concentrated for continuous reuse. The structure of the target product is determined by nuclear magnetic resonance hydrogen spectrum and infrared spectrum, and the yield is about 87%.

Preferably, in the step (1), the solid phase porous material is selected from one or more of activated carbon, silica and MCM-41 molecular sieve; the heteropoly acid is one or more of phosphotungstic acid, phosphomolybdic acid, cesium phosphotungstate and sodium silicotungstate, and the mass concentration of the heteropoly acid aqueous solution is 5-15%.

Preferably, in the step (1), the reflux time is 4-6 h, and the cooling and standing time is 12-24 h; the drying temperature is 110-120 ℃, and the drying time is 2-6 h.

Preferably, the specific steps of step (2) are: putting the supported heteropolyacid catalyst prepared in the step (1) and an amide activating reagent into a reaction kettle, and adding water as a reaction solvent; then adding the reactants of acrylamide, paraformaldehyde and polymerization inhibitor in proportion, heating the system to the reaction temperature, reacting for a period of time, and continuing to insulate the clinker for a period of time until the reaction is complete after white solids are separated out.

Preferably, in the step (2), the amide activating reagent is selected from one or two of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride, N-hydroxysuccinimide, N-hydroxythiosuccinimide and 4-dimethylaminopyridine; the polymerization inhibitor is any one of p-methoxyphenol, p-hydroxyphenol and phenothiazine.

Preferably, in step (2), the supported heteropolyacid catalyst is added in an amount of 6 wt% to 15 wt% based on the acrylamide.

Preferably, in step (2), the molar ratio of acrylamide to amide activating agent is 1: (0.05-0.25), wherein the molar ratio of acrylamide to water is 1: (1.2-3.0), wherein the molar ratio of acrylamide to paraformaldehyde is 1: (0.92-0.98), wherein the molar ratio of acrylamide to polymerization inhibitor is 1: (0.005-0.01).

Preferably, in the step (2), the reaction temperature is 60-85 ℃, the reaction time is 0.5-3 h, the temperature of the heat preservation clinker is 45-75 ℃, and the time of the heat preservation clinker is 1-4 h.

Preferably, in the step (3), the temperature of the added diluted hot water is 50-80 ℃, the vacuum degree of the filtrate vacuum concentration is 50-100mmHg, the temperature of the filtrate vacuum concentration is 45-60 ℃, and the filtrate vacuum concentration is carried out until the volume of the filtrate is 1/2-2/3 of the original volume.

Preferably, in the step (3), the cooling crystallization temperature is 5-10 ℃, and the cooling crystallization time is 12-36 h.

Compared with the prior art, the invention has the advantages that: according to the invention, acrylamide and paraformaldehyde are used as reaction raw materials, and a supported heteropolyacid catalyst and an amide activating reagent are adopted for concerted catalysis to prepare N, N' -methylene bisacrylamide; the synergistic use of the supported heteropolyacid catalyst and the amide activating reagent can interact with carbonyl in acrylamide under the condition of not influencing the catalysis of heteropolyacid, so that a p-pi conjugated system of an amido bond is damaged, the nucleophilicity of amino is improved, the reaction activity of the amino and paraformaldehyde is enhanced, the selectivity of the reaction is greatly improved, the high-efficiency conversion of raw materials is realized under the condition of not adding a large amount of water as a reaction solvent, and the reaction yield is improved.

The heteropolyacid catalyst used in the invention is loaded in a solid phase, the reaction is carried out on the surface of the solid catalyst, a large amount of acid solvent does not exist in the system, and alkali liquor is not required to be added for neutralization in the post-treatment process, so that the post-treatment step is simplified, and the discharge of waste water is reduced; the supported heteropoly acid has high catalytic activity, the reaction temperature of the system is lower, the reaction time is shorter, the double bond high-temperature polymerization or other addition byproducts in acrylamide are avoided, and the energy consumption is greatly reduced; in addition, the preparation process is simple, the reaction conditions are mild, the prepared product is crystallized N, N' -methylene bisacrylamide, three wastes are not generated basically in the synthesis process, the used supported heteropoly acid and amide activating reagent can be recycled after treatment, and the production cost is reduced.

In conclusion, the method has the advantages of mild reaction process conditions, easiness in control, high safety, capability of obtaining high-purity products, simplicity in post-treatment and easiness in industrial production.

Drawings

FIG. 1 is a comparison graph of the IR spectra of N, N' -methylenebisacrylamide in example 1 of the present invention and a commercial sample;

FIG. 2 shows the NMR spectrum of N, N' -methylenebisacrylamide in example 1 of the present invention.

Detailed Description

The invention is described in further detail below with reference to the accompanying examples.

Example 1:

the synthesis method of N, N' -methylene bisacrylamide in the embodiment comprises the following steps:

adding 250mL of 15 wt% phosphotungstic acid solution into a 500L round-bottom flask, then adding 200g of activated silica microspheres (the diameter is 2.5-4mm), ensuring that the silica microspheres are completely immersed into the solution, heating and refluxing for 6 hours, cooling to room temperature, standing for 12 hours, filtering out the silica microspheres, drying in an oven at 110 ℃ for 3 hours, and recording the obtained catalyst as Cat HPW/SiO₂；

In a 1L reactor, 60g Cat HPW/SiO were added₂With 191g (1moL) of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride, 250mL of deionized water was added, 7.5g (0.06moL) of p-methoxyphenol and 710g (10moL) of acrylamide were added to the system at room temperature, and 288g (9.6moL) of paraformaldehyde was added to the system in portions with mechanical stirring. After the charging is finished, the temperature of the system is gradually increased to 75 ℃, the reaction is carried out for 1 hour at 75 ℃, then the temperature is slowly decreased to 60 ℃, and the clinker is kept warm for 2 hours until the reaction is completed. Then 150mL of deionized water at 60 ℃ was added to the system, and the silica microspheres in the system were filtered off with gauze while hot, and the silica microspheres were carefully washed with a small amount of deionized water (50mL) at 60 ℃. The resulting filtrate was carefully concentrated under vacuum to about 250mL (60 ℃, 80mmHg), poured into a crystallization kettle, slowly cooled to 5 ℃, and left to crystallize for 24 hours. Centrifuging to separate crystals in the system to obtain the target product, as shown in FIG. 1,2, which is a verification map of the sample obtained in this example.

Air-drying the separated crystal at room temperature to obtain 1340g of crystal, wherein the extraction rate of the obtained crystal is 87.18%.

Example 2:

the synthesis method of N, N' -methylene bisacrylamide in the embodiment comprises the following steps:

250mL of 6 wt% phosphomolybdic acid solution is added to a 500mL round bottom flask, then about 200g of activated MCM-41 molecular sieve is added, the molecular sieve is fully immersed in the solution, heated and refluxed for 4 hours, cooled to room temperature, kept standing for 12 hours, filtered off, and dried in an oven at 110 ℃ for 3 hours. The resulting catalyst was designated Cat HPM/MCM.

In a 250mL round bottom flask, 20g of Cat HPM/MCM and 38g (0.2moL) of 1- (3-dimethylaminopropyl) -3-ethylcarbodiimide hydrochloride and 24g (0.2moL) of 4-dimethylaminopyridine were added, 200mL of deionized water was added, 2.2g (0.02moL) of hydroquinone and 287g (4moL) of acrylamide were added to the system, mechanical stirring was performed at room temperature, and 117g (3.92moL) of paraformaldehyde was added to the system in portions. After the charging is finished, the temperature of the system is gradually increased to 75 ℃, the reaction is carried out for 0.5 hour at 75 ℃, then the temperature is slowly decreased to 65 ℃, and the clinker is kept warm for 2 hours until the reaction is completed. Then 150mL of deionized water at 65 ℃ was added to the system, and the silica microspheres in the system were filtered off while hot with gauze and carefully washed with a small amount of deionized water (about 25mL) at 65 ℃. The filtrate was carefully concentrated under vacuum to about 200mL (60 ℃, 80mmHg), poured into a crystallization kettle, slowly cooled to 5 ℃, and left to crystallize for 24 hours. And (3) centrifugally separating crystals in the system, and air-drying at room temperature to obtain 540g of crystals, wherein the extraction rate of the obtained crystals is 87.54%.