A method for preparing methylphenylvinylsilanol

Abstract

The application relates to the field of high polymer chemistry and discloses a preparation method of methylphenylvinylsilanol, which uses methylvinyl dichlorosilane and a phenyl Grignard reagent as raw materials to prepare the methylphenylvinylsilanol, uses trialkyl orthoformate to eliminate the adverse effect of water in the system on the methylvinyl dichlorosilane, avoids the generation of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane which has a boiling point close to that of the methylphenylvinylsilanol, improves the content and yield of the methylphenylvinylsilanol, and overcomes the problems of difficulty in obtaining raw materials, high cost and inability to realize industrial production in the existing preparation process of the methylphenylvinylsilanol; the reaction steps are simple and reliable, the operation is simple, and the yield is high.

Description

Technical Field

[0001] This invention relates to the field of polymer chemistry, and in particular to a method for preparing methylphenylvinylsilanol. Background Technology

[0002] Silanols are small molecule compounds containing Si-OH groups. Because Si-OH is a reactive functional group, silanols readily undergo intermolecular dehydration to form disiloxanes in the presence of acids or bases. The type and nature of the organic functional groups attached to the silicon atom determine the stability and applications of silanol compounds. For example, when three methyl functional groups are attached to the silicon atom, i.e., when the silanol is trimethylsilanol, it is difficult to maintain stability at room temperature. However, when sterically hindered organic functional groups such as phenyl functional groups are attached to the silicon atom, the resulting phenylsilanol, such as diphenylsilanediol (also known as diphenyldihydroxysilane), is a relatively stable small molecule compound at room temperature. Diphenylsilanediol is widely used as a structure control agent in high-temperature vulcanized silicone rubber.

[0003] Besides being used as structure-controlling agents, silanols can also be used as end-capping agents or chain extenders in organosilicon polymerization. Furthermore, silanols can react with alkali metals to yield metal salts of silanols such as lithium silanolates, sodium silanolates, and potassium silanolates. These metal salts can be used as initiators for cyclotrisiloxane compounds with high ring strain, such as hexamethylcyclotrisiloxane, hexaethylcyclotrisiloxane, trimethyltriphenylcyclotrisiloxane, and trimethyltri(trifluoropropyl)cyclotrisiloxane. Initiating non-equilibrium anionic polymerization of cyclotrisiloxane compounds in ether solvents, followed by condensation reactions with monofunctional chlorosilanes, can produce special linear organosilicon polymers with narrow molecular weight distribution (low PDI value) and identical or different end-group structures. In addition to reacting with alkali metals to form lithium alkoxides, silanols can also undergo dehydrogenation reactions with alkyl lithiums such as n-butyllithium and tert-butyllithium to form lithium alkoxides, thereby further expanding the preparation methods of lithium silanolates.

[0004] Whether used as a capping agent, chain extender, or key raw material for the non-equilibrium polymerization of cyclotrisiloxane compounds, the types of other organic functional groups attached to the silicon atoms in the silanol molecule not only affect the stability and reactivity of the silanol, but also the reactivity and physicochemical properties such as refractive index and viscosity of the resulting organosilicon polymer. The chemical structure of methylphenylvinylsilanol is shown in formula (1). In addition to silanol groups, its molecule also contains methyl, phenyl, and vinyl functional groups. The presence of phenyl functional groups can improve the refractive index, high temperature resistance, and radiation resistance of organosilicon polymers. The presence of vinyl functional groups allows organosilicon polymers to be cross-linked and cured by hydrosilylation. Therefore, methylphenylvinylsilanol, as a capping agent for organosilicon polymers, can be used to prepare organosilicon polymers with high refractive index, high temperature resistance, radiation resistance, and curability by hydrosilylation. These organosilicon polymers have very important and wide applications in the packaging of Mini LED, MicroLED and other optoelectronic display devices and the packaging materials of high-power LED lighting devices.

[0005]

[0006] To prepare methylphenylvinylsilanol, patent WO 2021168228 discloses a method for preparing methylphenylvinylsilanol by using methylphenylvinylsilane (MePhViSiH) as a raw material and ruthenium metal compound as a catalyst, through a dehydrogenation reaction with an aqueous solution of acetonitrile, achieving a yield of 90%. (Angewandte Chemie, International...) Edition, 60(4), 1839-1844; 2021) discloses a method for preparing methylphenylvinylsilane by dehydrogenation reaction using methylphenylvinylsilane (MePhViSiH) as raw material, N-hydroxyphthalimide and tetrabutylammonium hexafluorophosphate (nBu4NPF6) as catalysts, and acetonitrile as solvent, with a yield of 61%; Organometallics (Organometallics, 39(1), 165-171; 2020) discloses a method for preparing methylphenylvinylsilane by dehydrogenation reaction with water using methylphenylvinylsilane (MePhViSiH) as raw material, iridium (Ir) complex as catalyst, and tetrahydrofuran as solvent, with a yield of 92%; Molecular Catalysis (Molecular Catalysis) Catalysis (452, 167-174; 2018) discloses a method for oxidizing methylphenylvinylsilane (MePhViSiH) to methylphenylvinylsilanol and its dimer (1,3-dimethyl-1,3-diphenyl-1,3-divinyldisiloxane) using methylphenylvinylsilane (MePhViSiH) as a raw material, acetonitrile as a solvent, polyoxomolybdate containing mixed valence Sb as a heterogeneous catalyst, and tert-butylhydrogen peroxide as an oxidant, with a yield of 84%.7%, wherein the mass ratio of methylphenylvinylsilane to 1,3-dimethyl-1,3-diphenyl-1,3-divinyldisiloxane is 92:8; ChemPhysChem (ChemPhysChem, 16(8), 1603-1606; 2015) disclosed a method for generating methylphenylvinylsilane from water using methylphenylvinylsilane (MePhViSiH) as a raw material, acetone as a solvent, and nano-copper as a catalyst, with a yield of 80%; CatalysisCommunications (Catalysis Communications, 53, 53-56; 2014) disclosed a method for generating methylphenylvinylsilane from water using methylphenylvinylsilane (MePhViSiH) as a raw material, nano-silver as a catalyst, and acetone as a solvent, with a yield of 90%; Chemical Communications (Chemical Communications (Cambridge, United States) Kingdom), 49(4), 376-378; 2013) disclosed a discrete octahedron [Ag6] encapsulated in a silicot ligand using methylphenylvinylsilane (MePhViSiH) as a raw material and acetonitrile as a solvent. 4+ A method for preparing methylphenylvinylsilane with water in the presence of oxygen using a cluster compound as a catalyst yielded 95%; Angewandte Chemie (Angewandte Chemie, International Edition, 51(10), 2434-2437, S2434 / 1-S2434 / 13; 2012) disclosed a method for preparing diamond-shaped [Ag4] with methylphenylvinylsilane (MePhViSiH) as a raw material, acetonitrile as a solvent, and silicotungsticate ligands. 4+A method for preparing methylphenylvinylsilane by reacting a cluster compound with water as a catalyst, with a yield of 98%; Angewandte Chemie (Angewandte Chemie, International Edition, 49(52), 10093-10095, S10093 / 1-S10093 / 4; 2010) also disclosed a method for generating methylphenylvinylsilane by reacting it with water using methylphenylvinylsilane (MePhViSiH) as a raw material, acetone as a solvent, and gold nanoparticles as a catalyst, with a yield of 98%; Angewandte Chemie (Angewandte Chemie, International Edition, 47(41), 7938-7940; 2008) disclosed a method for generating methylphenylvinylsilane by reacting it with water using methylphenylvinylsilane (MePhViSiH) as a raw material and supported silver nanoparticles as a catalyst, with a conversion rate of 97% and a content ratio of methylphenylvinylsilane to disiloxane in the product greater than 99:1. Although methylphenylvinylsilane can be used as a raw material and appropriate catalysts, oxidants and solvents can be selected to obtain methylphenylvinylsilanol in high yield, the above reactions and processes all require methylphenylvinylsilane as a raw material and expensive catalysts. On the other hand, methylphenylvinylsilane has not yet been industrialized and there are no industrial products available on the market. As a result, the methylphenylvinylsilanol prepared by the above technical route is expensive and has no prospects for industrial application, which cannot meet the cost control requirements of optoelectronic device packaging materials.

[0007] Besides using methylphenylvinylsilane as a raw material, Polymer Chemistry (Polymer Chemistry, 11(48), 7625-7636; 2020) reported a method for preparing methylphenylvinylsilanol using tetramethyltetravinylcyclotetrasiloxane and phenyllithium as raw materials, with diethyl ether as a solvent, reacting at 0°C for 26 h, with a yield of 26%. Although the tetramethyltetravinylcyclotetrasiloxane used in this technical route is a commercially available product, it requires the use of expensive phenyllithium reagent and has a yield of only 26%, making it difficult to industrialize this technical route. The cost of methylphenylvinylsilanol prepared using this technical route is unacceptable to optoelectronic packaging companies. Summary of the Invention

[0008] This invention aims to overcome the problems of high cost, limited raw material sources, and lack of industrialization in the preparation of methylphenylvinylsilanol in the prior art. It provides a method for preparing methylphenylvinylsilanol, using raw materials that are all products from industrial-scale production. This method has the advantages of simple process route, controllable reaction process, and high methylphenylvinylsilanol content, and has good prospects for industrialization.

[0009] To achieve the above objectives, the present invention adopts the following technical solution:

[0010] A method for preparing methylphenylvinylsilanol includes the following steps:

[0011] (1) Mix trialkyl orthoformate and tetrahydrofuran under dry and inert gas protection, and then add methyl vinyl dichlorosilane;

[0012] (2) Add the phenyl Grignard reagent dropwise to the reaction system. After the phenyl Grignard reagent is added, continue to maintain the reaction.

[0013] (3) After the alkylation reaction is completed, the solvent, unreacted raw materials and impurities in the system are removed by atmospheric distillation and then by vacuum distillation.

[0014] (4) After cooling to room temperature, filter to remove magnesium chloride generated in the reaction. Wash the filter cake with acetonitrile. Combine the washing liquid and filtrate and add dropwise to a saturated mixed solution of sodium bicarbonate and acetonitrile in a 1:1 mass ratio to carry out the hydrolysis reaction. After the addition is complete, maintain the reaction.

[0015] (5) Add ethyl acetate to the hydrolysis reaction mixture for extraction and separation. Add saturated sodium bicarbonate aqueous solution to the recovered organic layer until the pH is 6-8. Then separate the aqueous layer and the organic layer again, and add trialkyl orthoformate to the organic layer.

[0016] (6) The organic layer solution was subjected to vacuum distillation to remove the organic solvent and small molecule compounds, and a methylphenyl vinylsilanol solution was obtained.

[0017] The preparation process of the present invention is carried out according to the following reaction route: as in reaction formula (1), methylphenylvinylchlorosilane is prepared by alkylation reaction with phenyl Grignard reagent using methylvinyl dichlorosilane as raw material; then, as in reaction formula (2), methylphenylvinylchlorosilane is hydrolyzed and condensed in acetonitrile-water solution at low temperature to prepare methylphenylvinylsilanol.

[0018]

[0019] Chlorine-containing organosilicon monomers readily react with moisture in the air, releasing HCl and hydrolyzing chlorosilanes to form silanols. Among these, the difunctional silanols condense under HCl catalysis to form linear or cyclic oligomeric siloxanes. Although the atmospheric boiling point of methylvinyldichlorosilane is 93℃, the predicted atmospheric boiling point of methylphenylvinylchlorosilane is 206.9±13.0℃, and the predicted atmospheric boiling point of methylphenylvinylsilanol is 221.2±13.0℃, theoretically, excess or incompletely reacted methylvinyldichlorosilane can be easily separated from the reaction system. However, the atmospheric boiling point of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, generated from the hydrolysis of methylvinyldichlorosilane, is 229.00℃, close to that of methylphenylvinylsilanol. This makes it difficult to obtain high-purity methylphenylvinylsilanol using common distillation methods.

[0020] To eliminate the adverse effects of 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, generated from the reaction of methyl vinyl dichlorosilane with trace amounts of moisture in the system, on the content of methyl phenyl vinyl silanol, this invention proposes using trialkyl orthoformate as a moisture scavenger in the system. Taking advantage of the property of trialkyl orthoformate to generate low-boiling-point substances such as alkyl formate and alkyl alcohols from moisture in the system, this avoids the reaction of methyl vinyl dichlorosilane with water to generate 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, thereby increasing the content of methyl phenyl vinyl silanol in the product.

[0021] Preferably, in step (1), the mass ratio of the trialkyl orthoformate to tetrahydrofuran is (0.01-0.30):1, the mass ratio of methyl vinyl dichlorosilane to tetrahydrofuran is (0.15-0.75):1, and the material temperature in the reactor is controlled between -30°C and 30°C.

[0022] Preferably, in step (2), the phenyl Grignard reagent is a tetrahydrofuran solution of PhMgCl.

[0023] Preferably, in step (2), the molar ratio of phenyl Grignard reagent to methyl vinyl dichlorosilane is (0.75–0.95):1.

[0024] Since both active Si-Cl bonds in the methylvinyldichlorosilane molecule can undergo alkylation reactions with the phenyl Grignard reagent PhMgCl, the formation of the byproduct methyldiphenylvinylsilane should be suppressed as much as possible to obtain a high yield of methylphenylvinylchlorosilane and its hydrolysis condensation product methylphenylvinylsilanol. Controlling the molar ratio of the phenyl Grignard reagent to methylvinyldichlorosilane is a key factor in reducing the content of the byproduct methyldiphenylvinylsilane. Theoretically, the byproduct methyldiphenylvinylsilane can only be formed when the molar ratio of the phenyl Grignard reagent to methylvinyldichlorosilane exceeds 1:1. This application uses a feeding method where the phenyl Grignard reagent is added dropwise to a stirred methylvinyldichlorosilane solution for the reaction. However, the phenomenon of excessively high local concentrations of the phenyl Grignard reagent in the reaction system is still unavoidable; that is, there are local regions in the reaction system where the molar ratio of the phenyl Grignard reagent to methylvinyldichlorosilane is greater than 1:1, leading to the formation of the byproduct methyldiphenylvinylsilane. Therefore, by making the molar ratio of phenyl Grignard reagent to methyl vinyl dichlorosilane lower than the stoichiometric ratio, and by using an excess of methyl vinyl dichlorosilane, not only can the phenyl Grignard reagent react completely, avoiding safety hazards in the post-processing, but it also helps to reduce the content of the byproduct methyl diphenyl vinyl silane.

[0025] Preferably, in step (2), the reaction temperature is -30 to 25°C, and the phenyl Grignard reagent is added over a period of 1 to 10 hours; after the phenyl Grignard reagent is added, the reaction is maintained for 10 to 24 hours. Since the reaction is exothermic, the phenyl Grignard reagent cannot be added too quickly, otherwise the system temperature will be too high, leading to an increase in byproducts and affecting the reaction yield. Through dual control of the adding rate and the reactor temperature control system, the temperature inside the reactor is kept within a suitable range, ensuring the smooth progress of the reaction.

[0026] Preferably, in step (3), the atmospheric distillation temperature is 110–170°C, the vacuum distillation pressure is -101.2 kPa, and the vacuum distillation temperature is 110–170°C. During atmospheric distillation, tetrahydrofuran, excess or unreacted methylvinyldichlorosilane, trialkyl orthoformate, and their reaction products can be removed first, and then impurities in the system can be further removed by vacuum distillation to prevent these substances from interfering with subsequent reactions.

[0027] Preferably, in step (4), the mass ratio of acetonitrile to tetrahydrofuran in step (1) is (0.1-0.3):1; and the mass ratio of the saturated sodium bicarbonate and acetonitrile mixed solution to the mass ratio of methylvinyldichlorosilane in step (1) is (2.5-4.5):1.

[0028] Preferably, in step (4), the hydrolysis temperature is -10 to 10°C, the dripping time after the washing liquid and filtrate are combined is 1 to 5 hours, the reaction temperature is maintained at -10 to 10°C, and the reaction time is maintained at 1 to 5 hours.

[0029] Preferably, in step (5), the mass ratio of ethyl acetate to tetrahydrofuran in step (1) is (0.3-1.0):1; and the mass ratio of trialkyl orthoformate added to the organic layer to ethyl acetate is (0.01-0.25):1.

[0030] Preferably, in step (6), the pressure of vacuum distillation is -101.2 kPa and the temperature of vacuum distillation is 110 to 170 °C.

[0031] Therefore, the present invention has the following beneficial effects: (1) Methylphenylvinylsilane is prepared by using industrially produced methylvinyldichlorosilane and phenyl Grignard reagent PhMgCl as raw materials, which has the advantages of low cost and easy large-scale industrial production; (2) Trialkyl orthoformate is used to react with water in the reaction system, which avoids the hydrolysis of methylvinyldichlorosilane to generate 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane with a boiling point close to that of methylphenylvinylsilane, thereby increasing the content of methylphenylvinylsilane in the product and the yield of methylphenylvinylsilane. Attached Figure Description

[0032] Figure 1 This is the mass spectrum of methylphenylvinylsilanol prepared in Example 1. Detailed Implementation

[0033] The present invention will be further described below with reference to the accompanying drawings and specific embodiments. It should be understood that these embodiments are intended to illustrate the basic principles, main features, and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions used in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are generally those used in routine experiments. Unless otherwise specified in the following embodiments, all raw materials are commercially available or prepared by conventional methods in the art.

[0034] Example 1

[0035] A method for preparing methylphenylvinylsilanol includes the following steps:

[0036] (1) Add 5.0 g of trimethyl orthoformate and 177.84 g of tetrahydrofuran with a water content of less than 200 ppm to a 1 L jacketed reactor equipped with mechanical stirring. After stirring at room temperature for 30 minutes, add 101.57 g (0.72 mol) of methyl vinyl dichlorosilane. Pour ethanol coolant into the reactor jacket to cool the material inside the reactor to 10 °C.

[0037] (2) 300 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed 10 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol coolant. The dropping time was 3 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at 10 °C for 16 h.

[0038] (3) Transfer the reaction mixture to a de-lowering molecular reactor, gradually raise the temperature to 120°C, and remove the reaction solvent THF, trimethyl orthoformate, methyl formate (a product of the hydrolysis of trimethyl orthoformate), and excess methyl vinyl dichlorosilane and methyl vinyl dimethoxysilane (formed from methanol generated by the decomposition of trimethyl orthoformate) by atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-lowering reactor, gradually raise the temperature to 120°C at -101.2 kPa for vacuum distillation, and stop vacuum distillation when no more fractions escape.

[0039] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 40g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 300g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at 0℃ to carry out the hydrolysis reaction of methylphenylvinylchlorosilane. The addition time of methylphenylvinylchlorosilane was 2h. After the addition was completed, the temperature was maintained at 0℃ for another 2h.

[0040] (5) At this temperature, 150g of ethyl acetate was added for extraction. After separating the water layer and the organic layer using a separatory funnel, saturated sodium bicarbonate aqueous solution was added to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, 20g of trimethyl orthoformate was added to the organic layer to remove the water entrained in the organic layer.

[0041] (6) Remove the organic solvent from the organic layer at -101.2 kPa / 120 °C, and after cooling, obtain 89.6 g of methylphenyl vinylsilane solution.

[0042] The substances and their contents in the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The content of methylphenylvinylsilanol was 98.5%, and the content of methyldiphenylvinylsilane was 1.5%. The yield of methylphenylvinylsilanol was calculated to be 89.54%.

[0043] Example 2

[0044] A method for preparing methylphenylvinylsilanol includes the following steps:

[0045] (1) Add 10.0 g of trimethyl orthoformate and 200.2 g of tetrahydrofuran with a water content of less than 200 ppm to a 1 L jacketed reactor equipped with mechanical stirring. After stirring at room temperature for 30 minutes, add 101.57 g (0.72 mol) of methyl vinyl dichlorosilane. Pour ethanol coolant into the reactor jacket to cool the material inside the reactor to 0 °C.

[0046] (2) 280 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed 0 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol cooling solution. The dropping time was 5 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at 0 °C for 12 h.

[0047] (3) Transfer the reaction mixture to a de-lowering molecular reactor, gradually raise the temperature to 130°C, and remove the reaction solvent THF, trimethyl orthoformate, methyl formate (a product of the hydrolysis of trimethyl orthoformate), and excess methyl vinyl dichlorosilane and methyl vinyl dimethoxysilane (formed from methanol generated by the decomposition of trimethyl orthoformate) by atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-lowering reactor, and gradually raise the temperature to 130°C at -101.2 kPa for vacuum distillation. Stop vacuum distillation when no more fractions escape.

[0048] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 30g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 300g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at a temperature of -5℃ to carry out the hydrolysis reaction of methylphenylvinylchlorosilane. The addition time of methylphenylvinylchlorosilane was 2h. After the addition was completed, the temperature was maintained at -5℃ for another 3h.

[0049] (5) Add 120g of ethyl acetate for extraction. After separating the water layer and the organic layer using a separatory funnel, add saturated sodium bicarbonate aqueous solution to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, add 15g of trimethyl orthoformate to the organic layer to remove the water entrained in the organic layer.

[0050] (6) Remove the organic solvent from the organic layer at -101.2 kPa / 130 °C, and after cooling, obtain 85.3 g of methylphenyl vinylsilane solution.

[0051] The substances and their contents in the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The content of methylphenylvinylsilanol was 99.2%, and the content of methyldiphenylvinylsilane was 0.8%. The yield of methylphenylvinylsilanol was calculated to be 91.98%.

[0052] Example 3

[0053] A method for preparing methylphenylvinylsilanol includes the following steps:

[0054] (1) In a 1L jacketed reactor equipped with mechanical stirring, 50.0g of triethyl orthoformate and 300.0g of tetrahydrofuran with a water content of less than 200ppm were stirred at room temperature for 20 minutes, and then 101.57g (0.72mol) of methylvinyldichlorosilane was added. Ethanol coolant was circulated through the reactor jacket to cool the material in the reactor to -20℃;

[0055] (2) 330 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed -20 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol coolant. The dropping time was 7 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at -20 °C for 12 h.

[0056] (3) Transfer the reaction mixture to a de-lowering molecular reactor, gradually raise the temperature to 160°C, and remove the reaction solvent THF, triethyl orthoformate, methyl acetate (a product of the hydrolysis of triethyl orthoformate), and excess methyl vinyl dichlorosilane and methyl vinyl diethoxysilane (formed from ethanol generated by the decomposition of triethyl orthoformate) by atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-lowering reactor, and gradually raise the temperature to 160°C at -101.2 kPa for vacuum distillation. Stop vacuum distillation when no more distillate escapes.

[0057] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 50g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 400g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at a temperature of -10℃ to carry out the hydrolysis reaction of methylphenylvinylchlorosilane. The addition time of methylphenylvinylchlorosilane was 4h. After the addition was completed, the temperature was maintained at -10℃ for another 4h.

[0058] (5) Add 120g of ethyl acetate for extraction. After separating the water layer and the organic layer using a separatory funnel, add saturated sodium bicarbonate aqueous solution to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, add 20g of triethyl orthoformate to the organic layer to remove the water entrained in the organic layer.

[0059] (6) Remove the organic solvent from the organic layer at -101.2 kPa / 160 °C, and after cooling, obtain 100.7 g of methylphenyl vinylsilane solution.

[0060] The substances and their contents in the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The content of methylphenylvinylsilanol was 98.6%, and the content of methyldiphenylvinylsilane was 1.4%. The yield of methylphenylvinylsilanol was calculated to be 91.58%.

[0061] Comparative Example 1

[0062] The difference between this comparative example and the embodiment is that no water-removing agent is added during the preparation process. The specific preparation method includes the following steps:

[0063] (1) Add 101.57g (0.72mol) of methyl vinyl dichlorosilane to a 1L jacketed reactor with mechanical stirring, and then add 190.2g of tetrahydrofuran with a water content of less than 200ppm. Pass ethanol coolant into the reactor jacket to cool the material in the reactor to 10°C.

[0064] (2) 300 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed 15 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol coolant. The dropping time was 3 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at 15 °C for 16 h.

[0065] (3) Transfer the reaction mixture to a de-molecular-weight reactor, gradually raise the temperature to 120°C, and remove the reaction solvent THF and residual methyl vinyl dichlorosilane and other substances in the system by atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-molecular-weight reactor, and gradually raise the temperature to 120°C at -101.2 kPa for vacuum distillation. Stop vacuum distillation when no more distillate escapes.

[0066] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 40g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 300g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at 0℃ to carry out the hydrolysis reaction of methylphenylvinylchlorosilane. The addition time of methylphenylvinylchlorosilane was 2h. After the addition was completed, the temperature was maintained at 0℃ for another 2h.

[0067] (5) Add 150g of ethyl acetate for extraction. After separating the water layer and the organic layer using a separatory funnel, add saturated sodium bicarbonate aqueous solution to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, add 50g of anhydrous sodium sulfate to the organic layer to remove the water entrained in the organic layer.

[0068] (6) After filtration and desalination, the organic solvent in the filtrate was removed at -101.2 kPa / 120 °C, and after cooling, 87.6 g of methyl phenyl vinyl silanol solution was obtained.

[0069] The contents of the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The contents of 1,3,5-trimethyl-1,3,5-trivinylcyclotrisiloxane were 3.2%, 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane were 10.2%, methylphenylvinylsilanol was 78.6%, 1,3-dimethyl-1,3-divinyl-1,3-diphenyldisiloxane was 3.2%, and methyldiphenylvinylsilane was 4.8%. The yield of methylphenylvinylsilanol was calculated to be 69.85%.

[0070] As can be seen from Examples 1-3 and Comparative Example 1, the addition of the moisture scavenger trialkyl orthoformate can significantly reduce the formation of byproducts in the system, especially 1,3,5,7-tetramethyl-1,3,5,7-tetravinylcyclotetrasiloxane, thereby significantly increasing the yield of methylphenylvinylsilanol, improving the reliability of the preparation method, and making the preparation method have significant industrialization prospects.

[0071] Comparative Example 2

[0072] The difference between this comparative example and the embodiment is that an equal amount of phenyl Grignard reagent is used to react with methyl vinyl dichlorosilane, and the specific steps include the following:

[0073] (1) Add 20.0 g of trimethyl orthoformate and 177.84 g of tetrahydrofuran with a water content of less than 200 ppm to a 1 L jacketed reactor equipped with mechanical stirring. After stirring at room temperature for 30 minutes, add 101.57 g (0.72 mol) of methyl vinyl dichlorosilane. Pour ethanol coolant into the reactor jacket to cool the material inside the reactor to 10 °C.

[0074] (2) 360 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed 10 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol coolant. The dropping time was 1.5 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at 10 °C for 12 h.

[0075] (3) Transfer the reaction mixture to a de-molecular-weight reactor and gradually heat it to 120°C. Remove the reaction solvent THF, trimethyl orthoformate, methyl formate (a product of the hydrolysis of trimethyl orthoformate), and unreacted methyl vinyl dichlorosilane and methyl vinyl dimethoxysilane (formed from methanol generated by the decomposition of trimethyl orthoformate) by atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-molecular-weight reactor and gradually heat it to 120°C at -101.2 kPa for vacuum distillation. Stop vacuum distillation when no more distillate escapes.

[0076] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 40g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 400g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at 0℃ to carry out the hydrolysis reaction of chlorosilane. The dropwise addition time of the combined washing liquid and filtrate was 3h. After the dropwise addition was completed, the solution was maintained at 0℃ for another 2h.

[0077] (5) At this temperature, 150g of ethyl acetate was added for extraction. After separating the water layer and the organic layer using a separatory funnel, saturated sodium bicarbonate aqueous solution was added to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, 30g of trimethyl orthoformate was added to the organic layer to remove the water entrained in the organic layer.

[0078] (6) Remove the organic solvent from the organic layer at -101.2 kPa / 120 °C, and after cooling, obtain 99.7 g of methylphenyl vinylsilanol solution.

[0079] The substances and their contents in the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The content of methylphenylvinylsilanol was 85.7%, and the content of methyldiphenylvinylsilane was 14.3%. The yield of methylphenylvinylsilanol was calculated to be 72.24%.

[0080] Comparative Example 3

[0081] The difference between this comparative example and the embodiment is that a phenyl Grignard reagent with a molar ratio of 1:0.9 is used to react with methylvinyldichlorosilane, and the specific steps include the following:

[0082] (1) Add 20.0 g of trimethyl orthoformate and 201.15 g of tetrahydrofuran with a water content of less than 200 ppm to a 1 L jacketed reactor equipped with mechanical stirring. After stirring at room temperature for 30 minutes, add 91.41 g (0.648 mol) of methyl vinyl dichlorosilane. Pour ethanol coolant into the reactor jacket to cool the material inside the reactor to 10 °C.

[0083] (2) 360 mL of a 2 mol / L PhMgCl tetrahydrofuran solution was slowly added to the reactor through a constant pressure dropping funnel. The temperature of the reaction system was controlled to not exceed 10 °C by the dropping rate of the PhMgCl tetrahydrofuran solution and the temperature of the ethanol coolant. The dropping time was 3.0 h. After the PhMgCl tetrahydrofuran solution was completely added, the reaction continued at 10 °C for 18 h.

[0084] (3) Transfer the reaction mixture to a de-lowering molecular reactor, gradually raise the temperature to 120°C, and remove the reaction solvent THF, trimethyl orthoformate, methyl formate (a product of the hydrolysis of trimethyl orthoformate), and methyl vinyl dichlorosilane (formed from methanol generated by the decomposition of trimethyl orthoformate) using atmospheric distillation. After atmospheric distillation, transfer the remaining material in the reactor to a vacuum de-lowering reactor, gradually raise the temperature to 120°C at -101.2 kPa for vacuum distillation, and stop vacuum distillation when no more distillate escapes.

[0085] (4) After cooling to room temperature, magnesium chloride was removed by vacuum filtration. The filter cake was washed three times with 35g of acetonitrile, and the washing liquid and filtrate were combined. The combined washing liquid and filtrate were added dropwise to 250g of a mixed solution consisting of saturated sodium bicarbonate aqueous solution and acetonitrile in a 1:1 mass ratio and at 0℃ to carry out the hydrolysis reaction of methylphenylvinylchlorosilane. The addition time of methylphenylvinylchlorosilane was 4h. After the addition was completed, the temperature was maintained at 0℃ for another 2h.

[0086] (5) At this temperature, 130g of ethyl acetate was added for extraction. After separating the water layer and the organic layer using a separatory funnel, saturated sodium bicarbonate aqueous solution was added to the recovered organic layer to neutralize the solution pH to 6-8. After separating the water layer and the organic layer again, 28g of trimethyl orthoformate was added to the organic layer to remove the water entrained in the organic layer.

[0087] (6) Remove the organic solvent from the organic layer at -101.2 kPa / 120 °C, and after cooling, obtain 94.8 g of methylphenyl vinylsilanol solution.

[0088] The substances and their contents in the prepared methylphenylvinylsilanol solution were analyzed by GC-MS. The content of methylphenylvinylsilanol was 63.5%, and the content of methyldiphenylvinylsilane was 36.5%. The yield of methylphenylvinylsilanol was calculated to be 63.62%.

[0089] Comparative Examples 2 and 3, along with Examples 1-3, show that when the molar ratio of phenyl Grignard reagent to methyl vinyl dichlorosilane is lower than the stoichiometric ratio, resulting in an excess of methyl vinyl dichlorosilane, the formation of the byproduct methyl diphenyl vinyl silane can be reduced, significantly increasing the yield of methyl phenyl vinyl silanol. Furthermore, since the phenyl Grignard reagent is completely reacted, safety hazards in subsequent processing can be avoided.

Claims

1. A process for the preparation of methylphenylvinylsilanol, characterized in that, The method comprises the following steps: (1) mixing trialkyl orthoformate and tetrahydrofuran under dry and inert gas protection, and then adding methylvinyl dichlorosilane; (2) adding phenyl Grignard reagent dropwise into the reaction system, and continuing to maintain the reaction after the addition of the phenyl Grignard reagent is completed, wherein the molar ratio of the phenyl Grignard reagent to the methylvinyl dichlorosilane is (0.75-0.95):1; (3) after the completion of the alkylation reaction, removing the solvent, unreacted raw material and impurities in the system through normal pressure distillation and then vacuum distillation; (4) after being cooled to room temperature, filtering to remove the magnesium chloride generated in the reaction, washing the filter cake with acetonitrile, combining the washing liquid with the filtrate, and then adding the combined liquid dropwise into a mixed solution composed of saturated sodium bicarbonate and acetonitrile with a mass ratio of 1:1 to perform a hydrolysis reaction, and maintaining the reaction after the dropwise addition is completed; (5) adding ethyl acetate into the hydrolysis reaction mixture to perform extraction and separation, adding saturated sodium bicarbonate aqueous solution into the recovered organic layer until the pH is 6-8, and then separating the water layer and the organic layer again, and adding trialkyl orthoformate into the organic layer; (6) performing vacuum distillation on the organic layer solution to remove the organic solvent and small molecular compounds, and obtaining a methylphenylvinylsilanol solution; In step (1), the mass ratio of the trialkyl orthoformate to the tetrahydrofuran is (0.01-0.30):1, and the mass ratio of the methylvinyl dichlorosilane to the tetrahydrofuran is (0.15-0.75):1, and the temperature of the materials in the reactor is controlled to be between -30 and 30°C; In step (2), the phenyl Grignard reagent is a tetrahydrofuran solution of PhMgCl; In step (2), the reaction temperature is -30-25°C, the dropwise addition time of the phenyl Grignard reagent is 1-10 h, and the reaction is continued for 10-24 h after the dropwise addition of the phenyl Grignard reagent is completed.

2. The method for preparing methylphenylvinylsilanol according to claim 1, characterized in that, In step (3), the normal pressure distillation temperature is 110-170°C, the vacuum distillation pressure is -101.2 kPa, and the vacuum distillation temperature is 110-170°C.

3. The method for preparing methylphenylvinylsilanol according to claim 1, characterized in that, In step (4), the mass ratio of the acetonitrile to the tetrahydrofuran in step (1) is (0.1-0.3):1, and the mass ratio of the saturated sodium bicarbonate and acetonitrile mixed solution to the methylvinyl dichlorosilane in step (1) is (2.5-4.5):

1.

4. The method for preparing methylphenylvinylsilanol according to claim 1, characterized in that, In step (4), the hydrolysis temperature is -10-10°C, the dropwise addition time of the combined washing liquid and filtrate is 1-5 h, the maintained reaction temperature is -10-10°C, and the maintained reaction time is 1-5 h.

5. The method for preparing methylphenylvinylsilanol according to claim 1, characterized in that, In step (5), the mass ratio of the ethyl acetate to the tetrahydrofuran in step (1) is (0.3-1.0):1, and the mass ratio of the trialkyl orthoformate added into the organic layer to the ethyl acetate is (0.01-0.25):

1.

6. The method for preparing methylphenylvinylsilanol according to claim 1, characterized in that, In step (6), the vacuum distillation pressure is -101.2 kPa, and the vacuum distillation temperature is 110-170°C.

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