阅读说明：本技术 一种4-羟基丙烯酸丁酯的合成方法 (Synthesis method of 4-hydroxy butyl acrylate ) 是由 甄彬 苏敏超 杨凤智 于 2021-08-03 设计创作，主要内容包括：本发明属于光固化稀释剂的合成工艺开发领域,具体涉及一种4-羟基丙烯酸丁酯的合成方法。本发明提供的4-羟基丙烯酸丁酯的合成方法是在强酸性催化剂的催化作用下将1,4-丁二醇与丙烯醛脱水缩合环化获得2-乙烯基-1,3-二氧七环,接着在臭氧的作用下将2-乙烯基-1,3-二氧七环氧化开环获得4-羟基丙烯酸丁酯。本发明提供的4-羟基丙烯酸丁酯的合成方法具有方法简便、效率高,获得4-羟基丙烯酸丁酯产物纯度高和羟值高的优点,有利于该4-羟基丙烯酸丁酯的合成方法的推广和应用。(The invention belongs to the field of development of a synthesis process of a photocuring diluent, and particularly relates to a synthesis method of 4-hydroxy butyl acrylate. The synthesis method of the 4-hydroxy butyl acrylate provided by the invention comprises the steps of dehydrating, condensing and cyclizing 1, 4-butanediol and acrolein under the catalytic action of a strong acid catalyst to obtain 2-vinyl-1, 3-dioxoheptanes, and then epoxidizing and opening the 2-vinyl-1, 3-dioxoheptanes under the action of ozone to obtain the 4-hydroxy butyl acrylate. The synthesis method of the 4-hydroxy butyl acrylate provided by the invention has the advantages of simple method, high efficiency, high purity and high hydroxyl value of the obtained 4-hydroxy butyl acrylate product, and is beneficial to popularization and application of the synthesis method of the 4-hydroxy butyl acrylate.)

1. The synthesis method of 4-hydroxy butyl acrylate is characterized by comprising the following steps:

s1, adding 1, 4-butanediol and acrolein into a three-neck round-bottom flask, sequentially adding a polymerization inhibitor, benzene and a catalyst, placing the three-neck round-bottom flask into an oil bath pot, heating until reaction liquid flows back, separating generated water in the reaction process, and stopping the reaction after the reaction is carried out for 2-10 hours until the reaction is not regenerated into water to obtain reaction liquid I;

s2, cooling the reaction solution I obtained in the step S1 to room temperature, adding a 10% sodium hydroxide aqueous solution in volume concentration, and washing with saturated saline solution for 2-3 times to obtain a reaction solution II;

s3, placing the reaction liquid II obtained in the step S2 in a liquid nitrogen tank, introducing ozone under the stirring condition, wherein the introduction rate of the ozone is 0.1-10 mL/min, analyzing the components of the reaction liquid II through gas chromatography after reacting for 3-4 hours, stopping the reaction when the signal peak of 2-vinyl-1, 3-dioxoheptacyclo in the reaction liquid II completely disappears, introducing nitrogen, and distilling under reduced pressure to obtain the product.

2. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the ratio of the amounts of 1, 4-butanediol to acrolein in step S1 is 1 (1.1-1.8).

3. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the amount of polymerization inhibitor added in step S1 is 0.27-1.67% of the total weight of 1, 4-butanediol.

4. The method for synthesizing 4-butylacrylate as claimed in claim 1, wherein the polymerization inhibitor in step S1 is one or a combination of more than two of phenothiazine, hydroquinone and p-hydroxyanisole.

5. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the ratio of benzene to 1, 4-butanediol in S1 is 1mL (0.18-1.8) g.

6. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the amount of catalyst added in step S1 is 0.5-5.6% by weight based on the total weight of 1, 4-butanediol.

7. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the catalyst used in step S1 is one or a combination of two or more selected from the group consisting of p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, sulfuric acid and sodium bisulfate.

8. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein in step S3, the reaction solution II is placed in a liquid nitrogen tank, and ozone is not introduced until the temperature of the reaction solution II is cooled to-50 ℃.

9. The method for synthesizing 4-hydroxybutyl acrylate according to claim 1, wherein the vacuum distillation in step S3 is performed under the following conditions: the distillation was carried out at 50 ℃ under reduced pressure.

Technical Field

The invention belongs to the field of development of a synthesis process of a photocuring diluent, and particularly relates to a synthesis method of 4-hydroxy butyl acrylate.

Background

In recent years, the photo-curing industry has been rapidly developed and is changing day by day. The photocuring technology and the electron beam curing technology have the technical characteristics of high efficiency, wide adaptability, economy, energy conservation and environmental friendliness, are widely applied to the fields of coating, printing, photoresist, additive manufacturing and the like by virtue of unique advantages, and continuously develop updated and better photocuring products.

The photocured product is mainly composed of three parts, namely a reactive diluent, an oligomer and a photoinitiator. The group imparting photocuring activity to the photocured product is mainly an acrylate group (H)₂C ═ CHCOO —), methacrylate group (H)₂C＝C(CH₃) COO-), vinyl ether group (H)₂C ═ CH-O-), epoxy three membered cyclic group (CH)₂(O) CH-), an oxetane group (CH)₂(O)CH₂CH-). Currently, the most widely used light-curable products are acrylates. Among them, hydroxyalkyl acrylate is a very important photo-curing monomer, mainly comprising hydroxyethyl acrylate (HEA), hydroxypropyl acrylate (HPA), 4-hydroxybutyl acrylate (4-HBA). The hydroxyalkyl acrylate can be further reacted with an oligomer containing an isocyanate group to produce a urethane acrylate oligomer having photocuring activity.

Compared to HEA and HPA, 4-HBA has numerous advantages: (1) hydroxyl has higher reactivity; (2) the hardness of polyurethane synthesized by taking 4-HBA as a raw material is higher; (3) the coating has better low-temperature flexibility, scratch resistance and weather resistance.

The synthesis method of 4-HBA mainly comprises an esterification method and an ester exchange method. The 4-HBA is synthesized by an ester exchange method, which is mainly characterized in that 1, 4-butanediol and acrylic acid low-carbon alcohol ester are subjected to ester exchange reaction; the esterification method mainly adopts 1, 4-butanediol and acrylic acid to carry out esterification reaction. No matter the ester exchange method or the esterification method is adopted, 1, 4-butanediol diacrylate and 4-hydroxyl butyl acrylate are simultaneously generated in the process of synthesizing the 1, 4-butanediol acrylate. Therefore, it is necessary to obtain 4-hydroxybutyl acrylate with higher purity by purification. The crude liquid before purification generally contains 1, 4-butanediol, 4-hydroxybutyl acrylate and 1, 4-butanediol diacrylate, the boiling points of the three are close, and the analysis by a rectification method is difficult. In addition, the acrylic ester products are easily polymerized under heating, which is also an important reason for the difficulty of separation by the rectification process.

The Lanjun Yu of Qingdao university of science and technology adopts extraction method to extract 4-HBA from crude liquid, when the extraction rate is 74.4%, the purity of 4-hydroxybutyl acrylate reaches 79.45%, and the process is as follows (the research and optimization of Lanjun Yu, the process of synthesizing 4-hydroxybutyl acrylate by direct esterification method, Master thesis of Qingdao university of science and technology, Qingdao university of technology and technology, Lanjun Yu, the process of synthesizing 4-hydroxybutyl acrylate by direct esterification method

German Basff company adopts large excess 1, 4-butanediol to esterify with acrylic acid, after obtaining a mixed aqueous solution of 4-HBA and 1, 4-butanediol, a strong protonic acid catalyst is added to promote the 1, 4-butanediol to be converted into tetrahydrofuran with low boiling point, and finally the tetrahydrofuran is distilled and removed to obtain the 4-HBA with the purity of 99 percent (the process is shown as below). However, 98% of the 1, 4-butanediol is converted to tetrahydrofuran in this process (Shanghai paint, 2010,48(3): 16-18.).

The two methods have the problems of complex process, low product yield, high cost and the like.

Disclosure of Invention

In order to solve the defects in the prior art, the invention provides a synthesis method of 4-hydroxy butyl acrylate. The synthesis method of the 4-hydroxy butyl acrylate provided by the invention comprises the steps of dehydrating, condensing and cyclizing 1, 4-butanediol and acrolein under the catalytic action of a strong acid catalyst to obtain 2-vinyl-1, 3-dioxoheptanes, and then epoxidizing and opening the 2-vinyl-1, 3-dioxoheptanes under the action of ozone to obtain the 4-hydroxy butyl acrylate. The synthesis method of the 4-hydroxy butyl acrylate provided by the invention has the advantages of simple method, high efficiency, high purity of the obtained 4-hydroxy butyl acrylate product and high hydroxyl value.

The invention provides a synthesis method of 4-hydroxy butyl acrylate, which comprises the following steps:

s1, adding 1, 4-butanediol and acrolein into a three-neck round-bottom flask, sequentially adding a polymerization inhibitor, benzene and a catalyst, placing the three-neck round-bottom flask into an oil bath pot, heating until reaction liquid flows back, separating generated water in the reaction process, and stopping the reaction after the reaction is carried out for 2-10 hours until the reaction is not regenerated into water to obtain reaction liquid I;

the water separator is used for separating the generated water so as to promote the reaction.

S2, cooling the reaction solution I obtained in the step S1 to room temperature, adding a 10% sodium hydroxide aqueous solution in volume concentration, and washing with saturated saline solution for 2-3 times to obtain a reaction solution II;

the reaction solution II was washed with a dilute aqueous sodium hydroxide solution to remove the acidic catalyst added during the reaction, and then washed with a saturated aqueous sodium chloride solution to remove the residual sodium hydroxide.

S3, placing the reaction liquid II obtained in the step S2 in a liquid nitrogen tank, introducing ozone under the stirring condition, wherein the introduction rate of the ozone is 0.1-10 mL/min, after reacting for 3-4 h, sampling every 30min in the reaction process, analyzing the components of the reaction liquid II through gas chromatography, sampling every 30min in the reaction process, stopping the reaction when the signal peak of 2-vinyl-1, 3-dioxolane in the reaction liquid II completely disappears, introducing nitrogen, and distilling under reduced pressure to obtain the product.

The nitrogen gas is introduced to discharge ozone and oxygen dissolved in the reaction solution, and the nitrogen gas is removed by distillation under reduced pressure to remove benzene and other low boiling point substances.

Further, the ratio of the amount of the 1, 4-butanediol to the amount of acrolein in step S1 is 1 (1.1-1.8).

Further, the amount of the polymerization inhibitor added in step S1 is 0.27 to 1.67% of the total weight of 1, 4-butanediol.

Further, the polymerization inhibitor in step S1 is one or a combination of two or more of phenothiazine, hydroquinone and p-hydroxyanisole.

In step S1, the liquid-solid ratio of benzene to 1, 4-butanediol is 1mL (0.18-1.8) g.

Further, the amount of the catalyst added in the step S1 is 0.5-5.6% of the total weight of the 1, 4-butanediol.

Further, the catalyst in step S1 is one or a combination of two or more of p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, sulfuric acid and sodium bisulfate.

Further, in the step S3, the reaction solution II is placed in a liquid nitrogen tank, and the ozone is not introduced until the temperature of the reaction solution II is cooled to-50 ℃.

Further, the conditions of the reduced pressure distillation in the step S3 are: the distillation was carried out at 50 ℃ under reduced pressure.

The 4-hydroxy butyl acrylate (4-HBA) synthesized by the invention is called 4-Hydroxybutyl acrylate in English, and the CAS number is as follows: 2478-10-6, ENIECS: 257-130-8, the molecular formula is: c₇H₁₂O₃The molecular weight is: 144.1684.

in the traditional esterification synthesis method and ester exchange synthesis method of 4-hydroxy butyl acrylate, 1, 4-butanediol diacrylate and 4-hydroxy butyl acrylate are simultaneously generated in the process of synthesizing 1, 4-butanediol acrylate, and in the purification process, an acrylate product is easy to polymerize under the heating condition, the boiling point of a mixture is close to that of the product, and the mixture is difficult to separate by rectification. Therefore, the problems of complicated reaction process, high energy consumption, low product purity, poor product quality and the like are caused.

In order to solve the above problems, the present inventors have proposed a new route for efficiently synthesizing high-purity 4-butylacrylate by dehydrating, condensing and cyclizing 1, 4-butanediol and acrolein under the catalytic action of a strongly acidic catalyst to obtain 2-vinyl-1, 3-dioxaheptanes, and then epoxidizing and ring-opening the 2-vinyl-1, 3-dioxaheptanes under the action of ozone to obtain 4-butylacrylate.

The specific reaction principle of the synthesis method of 4-hydroxy butyl acrylate provided by the invention is as follows:

(1) the invention adopts 1, 4-butanediol and acrolein to synthesize 2-vinyl-1, 3-dioxohepta-cycle by dehydration condensation, adopts benzene as solvent, strong acids such as p-toluenesulfonic acid, methanesulfonic acid, phosphoric acid, sulfuric acid, sodium bisulfate and the like as catalysts, phenothiazine, hydroquinone, p-hydroxyanisole and the like as polymerization inhibitors, and removes the generated water out of a reaction system by benzene refluxing with water, wherein the reaction formula is as follows:

(2) the invention adopts dilute sodium hydroxide aqueous solution to wash the product solution, then sequentially uses saturated salt solution to wash, after the washing is finished, the product solution is placed in a liquid nitrogen tank, ozone is introduced under the stirring condition, the continuous reaction is carried out, 2-vinyl-1, 3-dioxohepta-epoxidation ring-opening synthesis of 4-hydroxy butyl acrylate is promoted, after the reaction is finished, nitrogen is introduced to discharge the ozone and oxygen dissolved in the solution, and finally the final product is obtained by removing the solvent and low boiling point substances through reduced pressure distillation, wherein the reaction formula is as follows:

compared with the prior art, the synthesis method of 4-hydroxy butyl acrylate provided by the invention has the advantages of simple operation, good repeatability and high efficiency, 1, 4-butanediol diacrylate and 4-hydroxy butyl acrylate do not need to be separated by rectification, and the obtained 4-hydroxy butyl acrylate product has high purity and high hydroxyl value, thereby being more beneficial to popularization and application of the synthesis method of 4-hydroxy butyl acrylate.

Description of the drawings:

FIG. 1 is a gas chromatogram of 2-vinyl-1, 3-dioxoheptanes in reaction liquid II of example 1;

FIG. 2 is a gas chromatogram of the product 4-butylacrylate of example 1;

FIG. 3 is a gas chromatogram of 2-vinyl-1, 3-dioxodeco-heptanes in reaction liquid II of example 2;

FIG. 4 is a gas chromatogram of the product 4-butylacrylate of example 2;

FIG. 5 is a gas chromatogram of 2-vinyl-1, 3-dioxodecoy ring in reaction liquid II of example 3;

FIG. 6 is a gas chromatogram of the product 4-butylacrylate of example 3.

Detailed Description

The present invention is further described in the following description of the specific embodiments, which is not intended to limit the invention, but various modifications and improvements can be made by those skilled in the art according to the basic idea of the invention, within the scope of the invention, as long as they do not depart from the basic idea of the invention.

Example 1 Synthesis method of 4-hydroxybutyl acrylate

S1, adding 180.24g (2mol) of 1, 4-butanediol and 123.33g (2.2mol) of acrolein into a 2000mL three-neck round-bottom flask, sequentially adding 1g of phenothiazine, 500mL of benzene and 3g of sodium bisulfate, then placing the three-neck round-bottom flask into an oil bath, heating until the reaction liquid refluxes, separating out the generated water by adopting a water separator in the reaction process, stopping the reaction after 8 hours of reaction until the reaction is not regenerated into water, and obtaining reaction liquid I, wherein the reaction liquid I is 2-vinyl-1, 3-dioxoheptacyclic solution;

s2, cooling the reaction liquid I obtained in the step S1 to room temperature, adding 100mL of 10% by volume aqueous solution of sodium hydroxide, washing with 100mL of saturated saline solution for 3 times, removing the catalyst and the unconverted 1, 4-butanediol raw material to obtain a reaction liquid II, wherein the reaction liquid II mainly contains solvent benzene and 2-vinyl-1, 3-dioxoheptacyclo, and the gas chromatogram of the reaction liquid II is shown in FIG. 1:

s3, placing the reaction liquid II obtained in the step S2 in a liquid nitrogen tank, when the temperature of the reaction liquid II is cooled to-50 ℃, introducing ozone under the stirring condition, wherein the introduction rate of the ozone is 0.5mL/min, reacting for 3h, stopping the reaction when the 2-vinyl-1, 3-dioxetane is completely converted through gas chromatography analysis, introducing nitrogen, carrying out reduced pressure distillation at the temperature of 50 ℃, removing low-boiling-point substances such as benzene and acrolein, and the like to obtain 4-butyl hydroxyacrylate, wherein the purity of the 4-butyl hydroxyacrylate in the final product is 95.8% through gas chromatography analysis, the hydroxyl value is 382.35mg KOH/g, and a gas chromatogram is shown in figure 2.

Example 2 Synthesis method of 4-hydroxy butyl acrylate

S1, adding 180.24g (2mol) of 1, 4-butanediol and 140.15g (2.5mol) of acrolein into a 2000mL three-neck round-bottom flask, sequentially adding 0.5g of phenothiazine and 0.5g of p-hydroxyanisole, 600mL of benzene and 5g of p-toluenesulfonic acid, then placing the three-neck round-bottom flask into an oil bath, heating until the reaction liquid refluxes, separating out generated water by using a water separator in the reaction process, stopping the reaction after 6 hours of reaction until the reaction is not regenerated into water, and obtaining a reaction liquid I, wherein the reaction liquid I is a 2-vinyl-1, 3-dioxoheptacyclic solution;

s2, cooling the reaction solution I obtained in step S1 to room temperature, adding 100mL of 10% by volume aqueous sodium hydroxide solution, washing the mixture with 100mL of saturated saline solution for 3 times, and removing the catalyst and the unconverted 1, 4-butanediol starting material to obtain a reaction solution II, wherein the gas chromatogram of the reaction solution II is shown in FIG. 3:

s3, placing the reaction liquid II obtained in the step S2 in a liquid nitrogen tank, when the temperature of the reaction liquid II is cooled to-50 ℃, introducing ozone under the stirring condition, wherein the introduction rate of the ozone is 0.5mL/min, reacting for 3h, stopping the reaction when the 2-vinyl-1, 3-dioxetane is completely converted through gas chromatography analysis, introducing nitrogen, carrying out reduced pressure distillation at the temperature of 50 ℃ to obtain 4-butyl hydroxyacrylate, analyzing the purity of the 4-butyl hydroxyacrylate in the final product through gas chromatography to be 96.6%, wherein the hydroxyl value is 385.41mg KOH/g, and the gas chromatogram thereof is shown in FIG. 4.

Example 3 Synthesis method of 4-hydroxy butyl acrylate

S1, adding 180.24g (2mol) of 1, 4-butanediol and 201.83g (3.6mol) of acrolein into a 2000mL three-neck round-bottom flask, sequentially adding 0.5g of phenothiazine and 0.5g of hydroquinone, 800mL of benzene and 4g of methanesulfonic acid, placing the three-neck round-bottom flask into an oil bath kettle, heating until the reaction liquid refluxes, separating out the generated water by using a water separator in the reaction process, stopping the reaction after reacting for 4.5h until the reaction is not regenerated into water, and obtaining a reaction liquid I, wherein the reaction liquid I is a 2-vinyl-1, 3-dioxoheptacyclic solution;

s2, cooling the reaction solution I obtained in step S1 to room temperature, adding 100mL of 10% by volume aqueous sodium hydroxide solution, washing the mixture with 100mL of saturated saline solution for 3 times, and removing the catalyst and the unconverted 1, 4-butanediol starting material to obtain a reaction solution II, wherein the gas chromatogram of the reaction solution II is shown in FIG. 5:

s3, placing the reaction liquid II obtained in the step S2 in a liquid nitrogen tank, when the temperature of the reaction liquid II is cooled to-50 ℃, introducing ozone under the stirring condition, wherein the introduction rate of the ozone is 0.5mL/min, reacting for 3h, stopping the reaction when the 2-vinyl-1, 3-dioxetane is completely converted through gas chromatography analysis, introducing nitrogen, carrying out reduced pressure distillation at the temperature of 50 ℃ to obtain 4-butyl hydroxyacrylate, analyzing the purity of the 4-butyl hydroxyacrylate in the final product through gas chromatography to be 96.9%, wherein the hydroxyl value is 384.88mg KOH/g, and a gas chromatogram thereof is shown in FIG. 6.

Comparative example 1, Synthesis method of 4-hydroxy butyl acrylate

A2000 mL three-necked round bottom flask was charged with 180.24g (2mol) of 1, 4-butanediol and 123.33g (2.2mol) of acrolein; 1g of phenothiazine, 500mL of toluene and 3g of sodium hydrogen sulfate are added in sequence, then the three-neck round-bottom flask is placed in an oil bath pot, the temperature is raised until the reaction liquid refluxes, a water separator is adopted to separate out the generated water in the reaction process, and after 24 hours of reaction, 1, 4-butanediol still remains in the reaction liquid. This is because acrolein is taken out of the reaction solution in a large amount during the reaction and dissolved in water, resulting in a large decrease in the acrolein content of the reaction solution, eventually resulting in incomplete conversion of 1, 4-butanediol.

Comparative example 2, Synthesis method of 4-hydroxy butyl acrylate

2-vinyl-1, 3-dioxetane was synthesized by the same protocol as in example 1, and neutralized and washed by the same method. When the ring opening is carried out by ozone oxidation, the reaction is carried out at the room temperature of 25 ℃. The reaction was found to be very rapid and completed within 10min, but at the same time the final product obtained was found to be an oligomer of 4-hydroxy butyl acrylate.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.