A process for the preparation of a methacryloyloxysilane

Abstract

The application discloses a preparation method of methacryloxy silane, comprising the following steps: adding allyl methacrylate into a solution containing trialkoxysilane and a platinum catalyst and a polymerization inhibitor, and reacting under heating to obtain 3-(methacryloxy) propyl trialkoxysilane; the platinum catalyst is composed of platinum acetylacetone and a promoter; the promoter is one or more of amine or phosphine organic reagents. The method avoids the occurrence of side reactions such as beta-addition, limits side reactions such as trialkoxysilane redistribution and product polymerization, improves the selectivity and yield of the product, reduces the total chlorine content of the product, and reduces the catalyst consumption.

Description

Technical Field

[0001] This invention relates to the field of organosilicon technology, and in particular to a method for preparing methacryloxysilane. Background Technology

[0002] Methacryloxysilanes are a class of widely used organosilane coupling agents, mainly used in unsaturated polyester composites. They can improve the mechanical, electrical, and light transmission properties of the composites, especially significantly improving their wet properties. When used as a sizing agent to treat glass fibers, they can improve the strength of glass fiber products and enhance their wet mechanical and electrical properties. When used to treat EPM and EPDM systems with crosslinked filler oxides, they can improve the consumption factor and specific inductance and capacitive reactance, while also improving the weather resistance of wires and cables.

[0003] The mainstream industrial method for producing 3-(methacryloyloxy)propyltrialkoxysilane involves a nucleophilic substitution reaction between sodium methacrylate and 3-chloropropyltrialkoxysilane. However, this reaction requires temperatures between 130°C and 160°C, at which temperature the product is prone to free radical polymerization, resulting in a lower yield. Furthermore, the reaction generates NaCl (US2002 / 0115878 Al), necessitating the addition of solvents such as DMF to improve mixing efficiency. This also requires an additional solvent recovery step in the post-processing, leading to high energy consumption. Additionally, the reactant 3-chloropropyltrialkoxysilane has a boiling point close to the product, resulting in a high total chlorine content in the distilled product.

[0004] The synthesis method of 3-(methacryloyloxy)propyltrialkoxysilane by hydrosilylation of trialkoxysilane with allyl methacrylate (AMA) was first reported by Knorre et al. in 1968 (DE 1271712). Subsequently, a research group at UCC in the United States used chloroplatinic acid as a catalyst (US4709067) to synthesize 3-(methacryloyloxy)propyltrialkoxysilane by hydrosilylation and achieved industrial production. However, the process temperature of chloroplatinic acid catalyst is difficult to control. The low starting reaction temperature makes it difficult to initiate the hydrosilylation reaction. Chloropinic acid causes the redistribution side reaction of the starting material trialkoxysilane, resulting in a decrease in reaction yield. When the starting reaction temperature is increased, the temperature of the reaction system rises rapidly after the addition reaction is initiated, leading to the occurrence of β-addition side reaction, which increases the difficulty of product purification and thus affects the water solubility and adhesive properties of the product. At the same time, it can also cause a series of side reactions such as product polymerization, resulting in a decrease in product yield (CN 110229181A, CN 101648967A), which limits the application of this synthesis method in industrial production.

[0005] Summary of the Invention

[0006] To address the aforementioned deficiencies in the prior art, this invention provides a method for preparing methacryloxysilane, which avoids side reactions such as β-addition and has advantages such as high selectivity, high yield, and high efficiency.

[0007] To achieve the above-mentioned objective, the first aspect of this invention provides a method for preparing methacryloxysilane, comprising the following steps:

[0008] Allyl methacrylate (AMA) is added to a solution containing a trialkoxysilane, a platinum catalyst, and a polymerization inhibitor, and reacted under heating conditions to obtain 3-(methacryloyloxy)propyltrialkoxysilane; the platinum catalyst is formed by coordination of platinum acetylacetonate with a promoter; the promoter is one or more of amine or phosphine organic reagents.

[0009] The platinum catalyst used in this invention is platinum acetylacetonate, which has a moderate initiation temperature and a minimal temperature rise after initiation, effectively suppressing side reactions such as polymerization.

[0010] In some specific embodiments, the accelerator is one or more of tetramethylethylenediamine, triethylamine, and triphenylphosphine, preferably tetramethylethylenediamine.

[0011] In some specific embodiments, the amount of platinum catalyst added is based on the amount of Pt, and the mass ratio of platinum catalyst to trialkoxysilane is 5 to 10 ppm, exemplarily 5 ppm, 6 ppm, 7 ppm, 8 ppm, 9 ppm, 10 ppm, etc., which is less than the amount of catalyst used in the prior art.

[0012] In some specific embodiments, the platinum catalyst used is obtained by dissolving platinum acetylacetonate in a solvent and mixing it with a promoter, and reacting it under reflux conditions for 1 to 2 hours to obtain the platinum catalyst. Exemplarily, the reaction is carried out at a temperature of 56°C and at atmospheric pressure.

[0013] In some specific embodiments, the molar ratio of the accelerator to platinum acetylacetone is 3 to 5:1, exemplarily 3:1, 4:1, 5:1, etc.

[0014] In some specific embodiments, the polymerization inhibitor is one or more of 2,6-di-tert-butylphenol, phenothiazine, or N,N-diphenyl-p-phenylenediamine, and the amount of the polymerization inhibitor added is 1-3 wt% of the mass of the trimekoxysilane. Adding the polymerization inhibitor can limit the occurrence of polymerization side reactions.

[0015] In some specific embodiments, the trialkoxysilane is trimethoxysilane or triethoxysilane; the molar ratio of the trialkoxysilane to AMA is 1:(0.95-1), preferably 1:(0.98-1).

[0016] In some specific embodiments, the reaction temperature under heating conditions is 90–125°C, exemplarily 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, etc. The reaction temperature described above in this invention is lower than that of mainstream methods for synthesizing KH570, which can limit the occurrence of polymerization side reactions and result in lower energy consumption.

[0017] In some specific embodiments, the preparation method of the methacryloxysilane includes the following steps: heating the trialkoxysilane to 90-95°C, adding a platinum catalyst and a polymerization inhibitor, starting to add AMA dropwise, controlling the temperature at 90-125°C during the dropwise addition process, maintaining the reaction at 90-125°C for 1-3 hours after the dropwise addition is complete, and then distilling to obtain the product 3-(methacryloyloxy)propyltrialkoxysilane.

[0018] In some specific embodiments, the distillation is vacuum distillation.

[0019] Compared with the prior art, the present invention has the following advantages:

[0020] Unlike existing technologies, this invention employs a catalytic system composed of platinum acetylacetonate and a promoter. AMA is added uniformly to a solution containing trialkoxysilane, a platinum catalyst, and a polymerization inhibitor. The reaction is carried out under heating conditions to obtain 3-(methacryloyloxy)propyltrialkoxysilane. The reaction diagram is as follows:

[0021]

[0022] The preparation method of this invention yields 3-(methacryloyloxy)propyltrialkoxysilane with an α-addition product to β-addition product ratio of 99%:1% to 99.9%:0.1%, and a total chlorine content of less than 30 ppm. This method avoids side reactions such as β-addition, limits side reactions such as trialkoxysilane redistribution and product polymerization, and improves product selectivity and yield.

[0023] Other features and advantages of the present invention will be described in detail through the following specific embodiments. Detailed Implementation

[0024] The following will clearly and completely describe the concept and technical effects of this application in conjunction with embodiments, so as to fully understand the purpose, features and effects of this application. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are all within the scope of protection of this application.

[0025] raw material:

[0026] Trimethoxysilane, INNOCHEM, 98%;

[0027] Triethoxysilane, INNOCHEM, 99%;

[0028] Allyl methacrylate, INNOCHEM, 99%;

[0029] Tetramethylethylenediamine, INNOCHEM, 99%;

[0030] 2,6-Di-tert-butylphenol, INNOCHEM, 99%;

[0031] Phenothiazide, INNOCHEM, 99%;

[0032] N,N-Diphenyl-p-phenylenediamine, INNOCHEM, 99%;

[0033] Gas chromatography instrument: Agilent 8890. Test method: Initial temperature 40℃, hold for 6 minutes; increase temperature by 5℃ / min to 80℃, hold for 0 minutes; increase temperature by 30℃ / min to 300℃, hold for 0 minutes.

[0034] Instrument used for NMR analysis: Bruker Avance 400MHz

[0035] Preparation of platinum catalysts:

[0036] 1g of platinum acetylacetonate was dissolved in 97.82g of acetone, and then 1.18g of tetramethylethylenediamine was added. The mixture was then refluxed for 1 hour (reaction temperature 56℃, pressure atmospheric pressure). After cooling, a liquid Pt catalyst was obtained, denoted as Al.

[0037] 1g of platinum acetylacetonate was dissolved in 97.82g of acetone, and then 2.66g of triphenylphosphine was added. The mixture was then refluxed for 1 hour (reaction temperature 56℃, pressure atmospheric pressure). After cooling, a liquid Pt catalyst was obtained, denoted as A2.

[0038] Example 1

[0039] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system temperature reached a maximum of 103 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1852 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 93%, an α-addition product to β-addition product ratio of 99.5%:0.5%, and a total chlorine content of 23 ppm. α-addition product structural information is also provided. 13 C-NMR chemical shifts (100 MHz, CDCl3): 5.3 (-CH2-Si-O-), 18.3 (CH3-CH-), 22.2 (CH2-(CH2)2-), 50.6 (CH3-O-Si), 66.0 (CH2-O), 125.0 (CH2-C=O), 136.7 (C-CH2), 167.0 (C=O). Structural information of the β-addition product. 13 C-NMR chemical shifts (100 MHz, CDCl3): 3.9 (CH3-CH-Si-), 18.3 (CH3-CH-), 21.9 (CH-Si-O-), 50.6 (CH3-O-Si), 66.0 (CH2-O), 125.0 (CH2-C=O), 136.7 (C-CH2), 167.0 (C=O).

[0040] Example 2

[0041] Under nitrogen protection, 1 kg of trimethoxysilane was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (A2) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system temperature was raised to a maximum of 100 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1792 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 90%, an α-addition product to β-addition product ratio of 99%:1%, and a total chlorine content of 17 ppm.

[0042] Example 3

[0043] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. Phenythiazide (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the maximum temperature of the reaction system reached 103 °C. After the AMA was completely added, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and approximately 1732 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 87%, an α-addition product to β-addition product ratio of 99.5%:0.5%, and a total chlorine content of 25 ppm.

[0044] Example 4

[0045] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. N,N-diphenyl-p-phenylenediamine (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the maximum temperature of the reaction system reached 103 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and approximately 1812 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 91%, an α-addition product to β-addition product ratio of 99.3%:0.7%, and a total chlorine content of 21 ppm.

[0046] Example 5

[0047] Under nitrogen protection, 1 kg of triethoxysilane was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. 768 g of AMA was added to the reactor at a rate of 4.8 g / min, and the reaction system temperature was raised to a maximum of 105 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and approximately 1646 g of a colorless, transparent liquid product at 125–132 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 94%, an α-addition product to β-addition product ratio of 99.5%:0.5%, and a total chlorine content of 15 ppm.

[0048] Example 6

[0049] Under nitrogen protection, 1 kg of trimethoxysilane was added to the reactor, and the mixture was stirred and heated to 105 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system reached a maximum temperature of 122 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1712 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 86%, an α-addition product to β-addition product ratio of 99%:1%, and a total chlorine content of 19 ppm.

[0050] Example 7

[0051] Under nitrogen protection, 1 kg of trimethoxysilane was added to the reactor, and the mixture was stirred and heated to 125 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system reached a maximum temperature of 143 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1294 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 65%, an α-addition product to β-addition product ratio of 97%:3%, and a total chlorine content of 34 ppm.

[0052] Example 8

[0053] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 2.04 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system temperature was raised to a maximum of 110 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1812 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 91%, an α-addition product to β-addition product ratio of 99.5%:0.5%, and a total chlorine content of 27 ppm.

[0054] Example 9

[0055] Under nitrogen protection, 1 kg of trimethoxysilane was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 2.58 mL of 0.5 wt% Pt catalyst (Al) were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system temperature was raised to a maximum of 110 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1832 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 92%, an α-addition product to β-addition product ratio of 99.5%:0.5%, and a total chlorine content of 24 ppm.

[0056] Comparative Example 1

[0057] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. 2,6-Di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% isopropanol solution of chloroplatinic acid were then added. AMA (1003 g) was added to the reactor at a rate of 4.8 g / min, and the reaction system reached a maximum temperature of 133 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1613 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 81%, an α-addition product to β-addition product ratio of 94%:6%, and a total chlorine content of 23 ppm.

[0058] Comparative Example 2

[0059] Under nitrogen protection, trimethoxysilane (1 kg) was added to the reactor, and the mixture was stirred and heated to 90 °C. Then, 2,6-di-tert-butylphenol (29 g) and 1.27 mL of 0.5 wt% isopropanol solution of chloroplatinic acid were added. AMA (1003 g) was added to the reactor at a rate of 2 g / min, and the reaction system temperature was raised to a maximum of 110 °C. After the AMA addition was complete, the mixture was kept at 95 °C and stirred for 1.5 hours to obtain the crude product. The crude product was subjected to vacuum distillation, and 1693 g of a colorless, transparent liquid product at 118–120 °C (1 mmHg) was collected. Gas chromatography analysis showed a purity of 98%, a yield of 85%, an α-addition product to β-addition product ratio of 95%:5%, and a total chlorine content of 27 ppm.

[0060] Compared to the embodiments of the present invention, the isopropanol solution using chloroplatinic acid in Comparative Examples 1-2 showed a significantly increased proportion of β-addition products and a decreased yield. Analysis suggests this is because the chloroplatinic acid catalyst has a longer initiation period for the hydrosilylation reaction in this type of reaction. At 90°C, chloroplatinic acid causes a redistribution side reaction in the starting material, trialkoxysilane, reducing the reaction yield. After initiating the addition reaction, the large accumulation of reactant AMA leads to a rapid increase in the reaction system temperature, resulting in redistribution side reactions and polymerization reactions, further reducing the product yield. Even with a reduced AMA addition rate and decreased AMA accumulation, the proportion of β-addition products remained high due to the absence of sterically hindered ligands, increasing the difficulty of product purification and consequently affecting the product's application performance.

[0061] In summary, this invention utilizes a catalytic system composed of platinum acetylacetonate and a promoter to uniformly add allyl methacrylate (AMA) to a solution containing trialkoxysilane, a platinum catalyst, and a polymerization inhibitor. Under heating conditions, 3-(methacryloyloxy)propyltrialkoxysilane is obtained with high selectivity, high efficiency, and high yield, avoiding side reactions such as β-addition, improving product yield and quality, and showing promise for industrial production.

[0062] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is impossible to exhaustively list all embodiments here. All obvious variations or modifications derived from the technical solutions of the present invention are within the spirit and scope of the present invention.

Claims

1. A method for preparing a methacryloyloxysilane, characterized in that, The method comprises the following steps: The allyl methacrylate is added to a solution containing trialkoxysilane and platinum catalyst, and a polymerization inhibitor, and reacted under heating to obtain 3-(methacryloyloxy) propyl trialkoxysilane; the platinum catalyst is prepared by complexing platinum acetylacetonate with a promoter; the promoter is one or more of amine or phosphine organic reagents; the promoter is one or more of tetramethyl ethylenediamine, triethylamine and triphenylphosphine.

2. The method for preparing methacryloxysilane according to claim 1, characterized in that, The promoter is tetramethyl ethylenediamine.

3. The method for preparing methacryloxysilane according to claim 1, characterized in that, The platinum catalyst is added in an amount of 5-10 ppm of platinum based on the mass ratio of platinum catalyst to trialkoxysilane.

4. The method for preparing methacryloxysilane according to claim 1, characterized in that, The platinum catalyst is obtained by dissolving platinum acetylacetonate in a solvent, mixing with a promoter, and keeping under reflux conditions for 1-2 hours to obtain the platinum catalyst.

5. The process for the preparation of methacryloxy silanes according to any one of claims 1 to 4, characterized in that, The molar ratio of the promoter to platinum acetylacetonate is 3-5:

1.

6. The method for preparing methacryloxysilane according to claim 1, characterized in that, The polymerization inhibitor is one or more of 2,6-di-tert-butyl phenol, phenothiazine or N,N-diphenyl-p-phenylenediamine, and the polymerization inhibitor is added in an amount of 1-3 wt% of the mass of trialkoxysilane.

7. The method for preparing methacryloxysilane according to claim 1, characterized in that, The trialkoxysilane is trimethoxysilane or triethoxysilane; and the molar ratio of the trialkoxysilane to allyl methacrylate is 1:(0.95-1).

8. The method of claim 7, wherein the methacryloxy silane is prepared by the process comprising: reacting a methacryloxy silane precursor with a reducing agent in the presence of a solvent to form the methacryloxy silane. The molar ratio of the trialkoxysilane to allyl methacrylate is 1:(0.98-1).

9. The method for preparing methacryloxysilane according to claim 1, characterized in that, The reaction temperature under heating is 90-125℃.

10. The method for preparing methacryloxysilane according to claim 1, characterized in that, The preparation method of the methacryloyloxy silane comprises the following steps: heating the trialkoxysilane to 90-95℃, adding the platinum catalyst and the polymerization inhibitor, starting to drop the allyl methacrylate, controlling the temperature at 90-125℃ during the dropping process, keeping at 90-125℃ for 1-3 hours after the dropping is completed, and then distilling to obtain the product 3-(methacryloyloxy) propyl trialkoxysilane.

11. The method of claim 10, wherein the methacryloxy silane is prepared by the process comprising: reacting a methacryloxy silane precursor with a reducing agent in the presence of a solvent to form the methacryloxy silane. The distillation is reduced pressure distillation.

Images