A method for the self-separation synthesis of trimethylolpropane triacrylate

Abstract

The application discloses a method for self-separation synthesis of trimethylolpropane triacrylate, and belongs to the technical field of fine chemical synthesis. A sulfonic acid functionalized polysilsesquioxane is used as a catalyst for trimethylolpropane and acrylation reaction, a water-carrying agent, a polymerization inhibitor and a reducing agent are introduced into the reaction system. The highest conversion rate of trimethylolpropane is 100%, and the selectivity of trimethylolpropane triacrylate is more than 90%. More importantly, the catalyst is easily dissolved in trimethylolpropane but not in the ester product, which makes the catalyst present as a homogeneous catalyst during the reaction, and the catalyst is spontaneously separated from the system after the reaction, so that the self-separation of the catalyst is realized.

Description

Technical Field

[0001] This invention belongs to the field of fine chemical synthesis technology, and relates to a method for synthesizing trimethylolpropane triacrylate, particularly a method for preparing self-separated trimethylolpropane triacrylate. Background Technology

[0002] Acrylic esters are an important class of organic chemicals, widely used in plasticizers, cosmetics, printing, and pharmaceuticals. Among them, trimethylolpropane triacrylate (TMPTA) plays an increasingly important role as a monomer in polymer materials. Traditionally, the esterification reaction of acrylic acid and trimethylolpropane (TMP) in industry primarily uses liquid acids such as H₂SO₄, HF, and CH₃SO₃H as catalysts. While these liquid acid catalysts exhibit good catalytic activity, they face challenges such as separation difficulties and equipment corrosion. To effectively address these issues, solid acid catalysts such as resins, zeolites, and supported inorganic acids have been developed. However, these solid acid catalysts are prone to deactivation and exhibit low catalytic activity, limiting their industrial application. Therefore, finding a highly active and reusable acid catalyst is particularly important.

[0003] Phase transfer catalysis is a catalytic process that has attracted much attention in recent years, possessing the advantages of homogeneous catalysis and heterogeneous separation. In particular, phase transfer reaction systems based on ionic liquids have been extensively reported in the literature, due to the fact that ionic liquids are green reaction media with negligible volatility, significant solubility, and structural designability. Brosted acidic ionic liquids (BILs), especially 1,3-propanesulfonate (PS) functionalized BILs, are promising alternatives to traditional catalysts, and their application as phase transfer catalysts in esterification reactions has been widely studied. For example, Davis first used alkanesulfonic acid ILs as solvent / catalyst for temperature-controlled liquid-liquid separation (Cole AC, Jensen JL, Ntai I, et al. Novel Brosted acidic ionic liquids and their use as dual solvent-catalysts[J]. Journal of the American Chemical Society, 2002, 124(21):5962-5963.). Fang et al. reported BILs as dual-solvent catalysts for Fischer esterification (Fang D, Zhou XL, Ye ZW, et al.). Acidic ionic liquids and their use as dual solvent-catalysts for Fischer esterifications[J]. Industrial & Engineering Chemistry Research, 2006, 45: 7892-7894.). In order to reduce the amount of IL used in the catalytic process, Leng et al. prepared a heteropolyacid anion-based "reaction-induced self-separation" catalyst, which can achieve homogeneous catalysis and heterogeneous separation in the reaction process (Leng Y, Wang J, Zhu D, et al. Heteropolyanion-based ionic liquids: reaction-induced self-separation catalysts for esterification[J]. Angewandte Chemie International edtion in English, 2009, 48(1): 168-71.). However, most phase transfer catalytic esterification reactions are still based on ionic liquid catalytic systems, and the application of phase separation catalysis technology in acrylic acid esterification reaction is still relatively rare. There is an urgent need to develop more phase separation catalysts and catalytic systems. Summary of the Invention

[0004] This invention addresses the difficulties in catalyst separation and recovery in existing catalytic systems for the esterification of acrylic acid and trimethylolpropane to trimethylolpropane triacrylate. It provides a method for the self-separation synthesis of trimethylolpropane triacrylate using a polysilsesquioxane sulfonic acid catalyst. By applying sulfonic acid-functionalized polysilsesquioxane to the esterification catalytic system of acrylic acid and trimethylolpropane, the catalyst achieves homogeneous catalysis. After the reaction, the catalyst precipitates from the reaction system, achieving heterogeneous separation. Therefore, this catalytic system combines the advantages of both homogeneous and heterogeneous catalytic systems, and the catalyst can be easily recovered and reused.

[0005] To address the above problems, this invention provides a method for the self-separation synthesis of trimethylolpropane triacrylate, comprising the following steps:

[0006] Acrylic acid, trimethylolpropane, a dehydrating agent, a polymerization inhibitor, and a reducing agent are added to a reactor equipped with a water separator. Then, a polysilsesquioxane sulfonic acid catalyst is added. The reaction is carried out at a temperature of 90–120°C for 10–18 hours to obtain an esterification reaction mixture. The mixture is then separated to obtain trimethylolpropane triacrylate. The polysilsesquioxane sulfonic acid catalyst has the following structural characteristics:

[0007]

[0008] In one embodiment of the present invention, the preparation method of the polysilsesquioxane sulfonic acid catalyst includes the following steps:

[0009] (1) Add organic solvent A, hydrochloric acid and 3-aminopropyltriethoxysilane into a round-bottom flask and stir at 50-80℃ for 12-24h. Then, add organic solvent B in the same volume as organic solvent A into the round-bottom flask, filter to obtain a white precipitate, wash the precipitate with organic solvent B several times, and finally dry it under vacuum at 50-70℃ to obtain functionalized polysilsesquioxane.

[0010] (2) Dissolve the functionalized polysilsesquioxane and alkyl sulfonate obtained in step (1) in organic solvent C, stir at 60-80℃ for 16-30h, separate the product by filtration or rotary evaporation, wash and dry to obtain polysilsesquioxane sulfonic acid catalyst.

[0011] In one embodiment of the present invention, organic solvent A and organic solvent C are one of methanol, ethanol, isopropanol, and ethylene glycol.

[0012] In one embodiment of the present invention, the organic solvent B is one or a mixture of several of ethyl acetate, cyclohexane, tetrahydrofuran, toluene, 1,2-dichloroethane, and n-hexane.

[0013] In one embodiment of the present invention, the alkyl sulfonate lactone is 1,3-propane sulfonate lactone or 1,4-butane sulfonate lactone.

[0014] In one embodiment of the present invention, the mass ratio of hydrochloric acid to 3-aminopropyltriethoxysilane is 1:1 to 2:1, and the total mass of hydrochloric acid and 3-aminopropyltriethoxysilane is 10% to 25% of the mass of organic solvent A.

[0015] In one embodiment of the present invention, the molar mass ratio of the functionalized polysilsesquioxane to the alkyl sulfonate lactone is 1:16 to 1:30, and the total mass of the functionalized polysilsesquioxane and the alkyl sulfonate lactone is 10% to 30% of the mass of the organic solvent C.

[0016] In one embodiment of the present invention, the molar ratio of acrylic acid to trimethylolpropane is 3:1 to 4:1.

[0017] In one embodiment of the present invention, the amount of the polysilsesquioxane sulfonic acid catalyst is 1 to 5% of the total mass of acrylic acid and trimethylolpropane.

[0018] In one embodiment of the present invention, the mass ratio of acrylic acid to dehydrating agent is 1:1 to 1:5, the amount of polymerization inhibitor is 2 to 5‰ of the total mass of acrylic acid and trimethylolpropane, and the amount of reducing agent is 2 to 5‰ of the total mass of acrylic acid and trimethylolpropane.

[0019] In one embodiment of the present invention, the dehydrating agent is one of n-hexane, cyclohexane, 1,1-dichloroethane, and toluene.

[0020] In one embodiment of the present invention, the polymerization inhibitor is one or more of phenothiazine, p-hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol, and cuprous chloride.

[0021] In one embodiment of the present invention, the reducing agent is one or more of polymethylhydrosiloxane, sodium bisulfite, sodium sulfite, hypophosphorous acid, phosphorous acid, and stannous oxide.

[0022] In one embodiment of the present invention, after solid-liquid separation of the obtained esterification reaction mixture, a polysilsesquioxane catalyst is recovered, which can be reused for the catalytic synthesis of trimethylolpropane triacrylate.

[0023] Beneficial effects of the present invention

[0024] (1) In this invention, polysilsesquioxane sulfonic acid catalyst is applied to the esterification reaction of trimethylolpropane and acrylic acid. The catalyst can achieve homogeneous catalysis. After the reaction is completed, the catalyst is precipitated from the reaction system, realizing heterogeneous separation. Therefore, the catalytic system has the advantages of both homogeneous and heterogeneous catalytic systems.

[0025] (2) In the catalytic reaction of the present invention, the catalyst has high catalytic activity, the conversion rate of reactants and the selectivity of products in the esterification reaction are high, the conversion rate of trimethylolpropane can be up to 100%, and the selectivity of trimethylolpropane triacrylate can be up to 92%.

[0026] (3) After the esterification reaction of the present invention, the catalyst can be easily recovered and reused. After the catalyst is reused 4 times, the catalytic activity is not significantly reduced. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the catalyst synthesis process.

[0028] Figure 2 This is a schematic diagram of the esterification reaction process in Example 3. Detailed Implementation

[0029] The present invention will be further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention.

[0030] Example 1

[0031] 60 mL of ethanol, 7 mL of hydrochloric acid, and 5 mL of 3-aminopropyltriethoxysilane were added to a round-bottom flask and stirred at 70 °C for 20 h. Then, 60 mL of tetrahydrofuran was added to the round-bottom flask containing the above mixture. After a white precipitate appeared, it was filtered, and the white precipitate was washed several times with tetrahydrofuran to remove impurities. Finally, the white precipitate was dried under vacuum at 60 °C to obtain aminopropyl-functionalized polysilsesquioxane (aminopropyl-functionalized POSS).

[0032] Aminopropyl-functionalized polysilsesquioxane and 1,3-propanesulfonate lactone were dissolved in 40 mL of ethanol at a molar ratio of 24:1 and stirred at 80 °C for 24 h. The product was distilled, washed repeatedly with ethyl acetate, and then dried under vacuum at 60 °C for 12 h to obtain the polysilsesquioxane sulfonic acid catalyst PS3-POSS.

[0033] Example 2

[0034] 60 mL of ethanol, 7 mL of hydrochloric acid, and 5 mL of 3-aminopropyltriethoxysilane were added to a round-bottom flask and stirred at 70 °C for 20 h. Then, 60 mL of tetrahydrofuran was added to the round-bottom flask containing the above mixture. After a white precipitate appeared, it was filtered, and the white precipitate was washed several times with tetrahydrofuran to remove impurities. Finally, the white precipitate was dried under vacuum at 60 °C to obtain aminopropyl-functionalized polysilsesquioxane (aminopropyl-functionalized POSS).

[0035] Aminopropyl-functionalized polysilsesquioxane and 1,3-propanesulfonic acid lactone were dissolved in 40 mL of ethanol at a molar ratio of 16:1 and stirred at 80 °C for 24 h. The product was distilled, washed several times with ethyl acetate, and then dried under vacuum at 60 °C for 12 h to obtain the polysilsesquioxane sulfonic acid catalyst PS. 2- POSS.

[0036] Example 3

[0037] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst PS3-POSS, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The preparation method of catalyst PS3-POSS was the same as in Example 1.

[0038] See the schematic diagram of the reaction process. Figure 2The reactants are added to a glass container and heated. The reactants change from a solid-liquid mixture to a liquid-liquid mixture, and the catalyst gradually dissolves into the reaction system. This is because the catalyst is soluble in the highly polar trimethylolpropane. As the reaction proceeds, trimethylolpropane reacts with acrylic acid to form trimethylolpropane acrylate. The content of trimethylolpropane in the system gradually decreases, while the catalyst, being insoluble in the ester product, gradually precipitates out of the system after the reaction is complete, achieving self-separation of the catalyst.

[0039] The yield (conversion rate of reactants) and selectivity of the product were calculated using the internal standard method based on the gas chromatogram. The results showed that the conversion rate of trimethylolpropane was 100% and the selectivity of trimethylolpropene was 92%.

[0040] Example 4

[0041] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst PS2-POSS, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The preparation method of catalyst PS2-POSS was the same as in Example 2.

[0042] Gas chromatography showed that the conversion rate of trimethylolpropane was 100% and the selectivity of trimethylolpropene was 90%.

[0043] Example 5

[0044] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst PS3-POSS, 8 g of cyclohexane, 10 mg of stannous oxide, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The preparation method of catalyst PS3-POSS was the same as in Example 1.

[0045] Gas chromatography showed that the conversion rate of trimethylolpropane was 98% and the selectivity of trimethylolpropane was 88%.

[0046] Example 6

[0047] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.2 g of catalyst PS3-POSS, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The preparation method of catalyst PS3-POSS was the same as in Example 1.

[0048] Gas chromatography showed that the conversion rate of trimethylolpropane was 95% and the selectivity of trimethylolpropene was 94%.

[0049] Example 7

[0050] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst PS3-POSS, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The preparation method of catalyst PS3-POSS was the same as in Example 1.

[0051] After the reaction was completed, the catalyst PS3-POSS was filtered out and reused three more times under the same reaction conditions. After each reaction, the selectivity of trimethylolpropionic acid ester and the conversion rate of the reactants were tested by gas chromatography.

[0052] Gas chromatography analysis showed that after three repeated uses of the catalyst, the selectivity of the obtained trimethylolpropane was 91%, 89%, and 90%, respectively, and the conversion rate of trimethylolpropane was 100% in all cases.

[0053] Comparative Example 1

[0054] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, add 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole. Heat the flask in an oil bath to 110 °C and react for 12 h. The catalyst is 98% sulfuric acid.

[0055] Gas chromatography showed that the conversion rate of trimethylolpropane was 98%, and the selectivity of trimethylolpropane was 82%.

[0056] The catalytic reaction system is homogeneous, and the catalyst cannot be recovered or reused.

[0057] Comparative Example 2

[0058] In a 50 mL three-necked flask equipped with a magnetic stir bar, a serpentine condenser, and a water separator, add 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst CH3SO3H, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole. Heat the oil bath to 110 °C and react for 12 h.

[0059] Gas chromatography showed that the conversion rate of trimethylolpropane was 95% and the selectivity of trimethylolpropene was 85%.

[0060] The catalytic reaction system is homogeneous, and the catalyst cannot be recovered or reused.

[0061] Comparative Example 3

[0062] In a 50 mL three-necked flask equipped with a magnetic stirrer, a serpentine condenser, and a water separator, 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of sulfonic acid resin solid catalyst, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole were added. The mixture was heated in an oil bath to 110 °C and reacted for 12 h. The sulfonic acid resin solid catalyst was p-toluenesulfonic acid resin.

[0063] Gas chromatography showed that the conversion rate of trimethylolpropane was 75%, while the selectivity of trimethylolpropane was only 43%.

[0064] The catalyst is insoluble in the reaction system, and the entire catalytic process is a liquid-solid phase catalysis.

[0065] Comparative Example 4

[0066] 60 mL of ethanol, 7 mL of hydrochloric acid, and 5 mL of 3-aminopropyltriethoxysilane were added to a round-bottom flask and stirred at 70 °C for 20 h. Then, 60 mL of tetrahydrofuran was added to the round-bottom flask containing the above mixture. After a white precipitate appeared, it was filtered, and the white precipitate was washed several times with tetrahydrofuran to remove impurities. Finally, it was dried under vacuum at 60 °C to obtain aminopropyl-functionalized POSS.

[0067] Aminopropyl-functionalized POSS and 1,3-propanesulfonic acid lactone were dissolved in 40 mL of ethanol at a molar ratio of 10:1 and stirred at 80 °C for 24 h. The product was distilled, washed several times with ethyl acetate, and then dried under vacuum at 60 °C for 12 h to obtain the polysilsesquioxane sulfonic acid catalyst PS1-POSS.

[0068] In a 50 mL three-necked flask equipped with a magnetic stir bar, a serpentine condenser, and a water separator, add 3.5 g of trimethylolpropane, 6.2 g of acrylic acid, 0.4 g of catalyst PS1-POSS, 8 g of cyclohexane, 10 mg of hypophosphite, and 5 mg of p-hydroxyanisole. Heat the oil bath to 110 °C and react for 12 h.

[0069] Gas chromatography analysis showed that when using the PS1-POSS catalyst, the conversion rate of trimethylolpropane was 53%, while the selectivity of trimethylolpropane was only 4%.

[0070] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Anyone skilled in the art can make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the claims.

Claims

1. A process for the self-separation synthesis of trimethylolpropane triacrylate, characterized in that, The process comprises adding acrylic acid, trimethylolpropane, water-carrying agent, polymerization inhibitor and reducing agent into a reactor with a water trap, then adding a polyhedral oligomeric silsesquioxane sulfonic acid catalyst, to obtain an esterification reaction mixture under the conditions of a reaction temperature of 90-120°C and a reaction time of 10-18 h, and then separating the mixture to obtain trimethylolpropane triacrylate; the polyhedral oligomeric silsesquioxane sulfonic acid catalyst has the structure of PS3-POSS or PS2-POSS as shown below: wherein represents , represents .

2. The method of claim 1, wherein, The preparation method of the polyhedral oligomeric silsesquioxane sulfonic acid catalyst comprises the following steps: (1) adding an organic solvent A, hydrochloric acid and 3-aminopropyl triethoxysilane into a round-bottom flask, stirring at 50-80°C for 12-24 h, then adding an organic solvent B with the same volume as the organic solvent A into the round-bottom flask, filtering to obtain white precipitate, washing the obtained precipitate with the organic solvent B for multiple times, and finally drying under vacuum at 50-70°C to obtain functionalized polyhedral oligomeric silsesquioxane; (2) dissolving the functionalized polyhedral oligomeric silsesquioxane and alkylsulfonic acid lactone in an organic solvent C, stirring at 60-80°C for 16-30 h, separating the product by filtration or rotary evaporation, washing and drying to obtain the polyhedral oligomeric silsesquioxane sulfonic acid catalyst.

3. The method of claim 2, wherein, The organic solvent A comprises one of methanol, ethanol, isopropanol and ethylene glycol, the organic solvent C comprises one of methanol, ethanol, isopropanol and ethylene glycol, and the organic solvent B comprises any one or mixture of several of ethyl acetate, cyclohexane, tetrahydrofuran, toluene, 1,2-dichloroethane and n-hexane.

4. The method of claim 2, wherein, The mass ratio of the hydrochloric acid and 3-aminopropyl triethoxysilane is 1:1-2:1, and the total mass of the hydrochloric acid and 3-aminopropyl triethoxysilane is 10%-25% of the mass of the organic solvent A.

5. The method of claim 2, wherein, The molar mass ratio of the functionalized polyhedral oligomeric silsesquioxane and alkylsulfonic acid lactone is 1:16-1:30, and the alkylsulfonic acid lactone comprises 1,3-propane sulfonic acid lactone or 1,4-butane sulfonic acid lactone.

6. The method of claim 1, wherein, The molar ratio of the acrylic acid and trimethylolpropane is 3:1-4:1, and the amount of the polyhedral oligomeric silsesquioxane sulfonic acid catalyst is 1-5% of the total mass of the acrylic acid and trimethylolpropane.

7. The method of claim 1, wherein, The amount of the polymerization inhibitor is 2-5‰ of the total mass of the acrylic acid and trimethylolpropane, the mass ratio of the acrylic acid and water-carrying agent is 1:1-1:5, and the mass of the reducing agent is 2-5‰ of the total mass of the acrylic acid and trimethylolpropane.

8. The method of claim 1, wherein, The polymerization inhibitor comprises any one or mixture of several of phenothiazine, p-hydroxyanisole, 2,6-di-tert-butyl-4-methylphenol and cuprous chloride.

9. The method of claim 1, wherein, The water-carrying agent comprises any one of n-hexane, cyclohexane, 1,1-dichloroethane and toluene, and the reducing agent comprises any one or mixture of several of polymethylhydrogenosiloxane, sodium bisulfite, sodium sulfite, hypophosphorous acid, phosphorous acid and stannous oxide.

10. The method of any one of claims 1-9, wherein, The obtained esterification reaction mixture is subjected to solid-liquid separation, and the polyhedral oligomeric silsesquioxane sulfonic acid catalyst is recovered, which can be repeatedly used for catalytic synthesis of trimethylolpropane triacrylate.

Images