A process for the preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane

Abstract

The application belongs to the technical field of silane capping agents, and particularly relates to a preparation method of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The preparation method comprises the following steps: S1, at 60-70 DEG C, dimethyl monochlorosilane gas and acetylene gas are simultaneously added into a solvent, under the action of a catalyst, and reaction is carried out at 0.2-0.5 MPa and 70-90 DEG C for 4-6 h to obtain a synthesis liquid, the synthesis liquid is distilled to obtain vinyl dimethyl monochlorosilane; S2, the vinyl dimethyl monochlorosilane is mixed with water vapor, and hydrolysis reaction is carried out under the pressure of 0.05-0.1 MPa through partition temperature control to obtain a reaction material, and the reaction material is distilled to obtain the 1,3-divinyl-1,1,3,3-tetramethlydisiloxane. Compared with the sodium condensation method, the continuous silicon hydrogenation reaction and water vapor hydrolysis method are adopted to realize the continuous production of 1,3-divinyl-1,1,3,3-tetramethyl disiloxane, the synthesis process is simple and safe, raw materials are easy to obtain, the cost is low, the product has low chlorine ions, and the efficiency is high.

Description

Technical Field

[0001] This invention belongs to the field of silane end-capping agent technology, specifically relating to a method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. Background Technology

[0002] 1,3-Divinyl-1,1,3,3-tetramethyldisiloxane (referred to as vinyl disiloxane) is a commonly used functional organosilane material, used as an additive or intermediate in the production of addition-cure silicone rubber, silicone gel, liquid silicone, vinyl silicone resin, vinyl silicone oil, platinum-chromium compounds, etc. The conventional method is to prepare dimethylvinylethoxysilane using the Grignard process with dimethyldiethoxysilane. The main synthetic methods for vinyl disiloxane include the Grignard reagent method and the sodium metal condensation method. The Grignard reagent method involves dissolving magnesium and bromomethane in an alkane solvent to form a Grignard reagent, which is then reacted with vinyltriethoxysilane to produce vinyldimethylethoxysilane, followed by hydrolysis to generate tetramethyldivinyldisiloxane. This method involves multiple reaction steps, and both the magnesium metal and the intermediate Grignard reagent have high reactivity. The reaction and transfer processes are risky, and the disposal of the intermediate magnesium salt is difficult.

[0003] Currently, the industrial production of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane mainly uses metallic sodium, dimethyldiethoxysilane, and vinyl chloride as raw materials. Under the action of metallic sodium, vinyl chloride reacts to produce dimethylvinylethoxysilane and its sodium salt. Dimethylvinylethoxysilane is then hydrolyzed to obtain tetramethyldivinyldisiloxane, and the resulting sodium salt is evaporated at high temperature and then packaged. This method has a yield of approximately 70%, but it requires a significant excess of dimethyldiethoxysilane to reduce side reactions and as a solvent, resulting in high costs. The reaction produces a large amount of sodium ethoxide as a byproduct, which poses a significant risk when mixed with sodium chloride and is difficult to handle. Furthermore, separating dimethylvinylethoxysilane from dimethyldiethoxysilane is challenging, leading to high energy consumption and low efficiency. Moreover, the storage, use, and post-processing of the raw material metallic sodium pose significant safety risks, potentially leading to serious accidents. Additionally, the sodium condensation method typically employs a single-reactor reaction, resulting in low reaction efficiency, consuming large amounts of metallic sodium, and producing sodium chloride as a byproduct, thus exhibiting low levels of environmental friendliness. Summary of the Invention

[0004] Based on this, the purpose of this invention is to provide a method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. Compared with the sodium condensation method, this method uses a continuous hydrosilylation reaction and steam hydrolysis to achieve the continuous production of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The synthesis process is simple, safe, uses readily available raw materials, has low cost, produces a product with low chloride ion content, and is highly efficient.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, comprising the following steps: S1, Preparation of vinyldimethylchlorosilane: Dimethylchlorosilane gas and acetylene gas are simultaneously added to the first solvent at 60~70℃. Under the action of a catalyst, the reaction is carried out at 0.2~0.5MPa and 70~90℃ for 4~6h to obtain a synthesis solution. The synthesis solution is then distilled to obtain vinyldimethylchlorosilane. S2, Preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane: The vinyl dimethyl chlorosilane described in S1 is mixed with water vapor and subjected to hydrolysis reaction under controlled temperature and partitioned pressure of 0.05~0.1 MPa to obtain a reaction material. The reaction material is then distilled to obtain the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

[0006] Further, in S1, the molar ratio of acetylene gas to dimethylchlorosilane gas is (5~12):1; the content of the first solvent in the synthesis solution is not less than 25%, and the first solvent includes xylene, toluene or tetrahydrofuran (THF); the catalyst is a platinum compound, and the content of Pt in the synthesis solution is 5~50 ppm of the mass fraction of dimethylchlorosilane.

[0007] Further, the preparation method of the platinum compound is as follows: under nitrogen protection, the second solvent is heated to 60±2℃, an auxiliary agent is added, an isopropanol solution of chloroplatinic acid hexahydrate is added, the temperature is raised to 100~105℃ and kept at the temperature for 1.5~2.5h, the temperature is lowered to below 60℃, a neutralizing agent is added for neutralization, a desiccant is added for drying, and the product is obtained by filtration.

[0008] Furthermore, the isopropanol solution of chloroplatinic acid contains 3.5-4% chloroplatinic acid, the additives, neutralizers, and desiccants are 8-10 times, 1.5-2 times, and 1.5-2 times the mass of chloroplatinic acid, respectively, and the second solvent is 7-8 times the mass of the additives.

[0009] Further, the additives include 1,3-divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylsilane hydrolyzed oligomers with a degree of polymerization of 10-50, or viscosities of 20-50 mm. 2 / s, a low-viscosity vinyl silicone oil with a vinyl content >2%, preferably 1,3-divinyl-1,1,3,3-tetramethyldisiloxane; the second solvent is consistent with the first solvent, preferably xylene; the neutralizing agent includes sodium bicarbonate, and the drying agent includes anhydrous magnesium sulfate.

[0010] More preferably, the steps for preparing the platinum compound are as follows: under nitrogen protection, 0.2 kg of xylene is heated to 60°C, 0.22 kg of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is added, 27 g of chloroplatinic acid in 750 ml of isopropanol solution is added, the temperature is raised to 100-105°C and kept at this temperature for 2 h, the temperature is lowered to below 60°C, 50 g of sodium bicarbonate and 50 g of anhydrous magnesium sulfate are added for neutralization and drying for 1 h, and the solids are removed by filtration to obtain the catalyst liquid.

[0011] Furthermore, the molar ratio of water vapor to vinyldimethylchlorosilane in S2 is (5~10):1.

[0012] Further, the preparation of vinyldimethylchlorosilane described in S1 is carried out in a first reaction tower. The height-to-diameter ratio of the first reaction tower is (3~5):1, and a first upper support and a second middle support are provided at a position 0.08~0.12 times the tower height from the top of the tower. A first lower support is provided at the bottom of the tower. The dimethylchlorosilane gas and acetylene gas enter the first reaction tower from the first upper support, the first solvent and catalyst enter the first reaction tower from the first lower support, and the synthesis liquid exits the first reaction tower from the second middle support and then enters the first distillation tower.

[0013] More preferably, the interior of the first reaction tower is lined with enamel material, with a diameter of 20cm, a height of 80cm, and a volume of 100L. A first upper support is provided at a position 8cm from the top of the tower. The synthesis pressure and pressure temperature inside the tower are 0.2~0.5MPa and 70~90℃, respectively. The content of the first solvent in the synthesis liquid inside the first reaction tower is maintained at not less than 25%. When the liquid level in the first reaction tower reaches 60cm, the solvent heated by the preheater is added to the first reaction tower through the first lower support via a flow meter.

[0014] Further, the preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane described in S2 is carried out in a second reaction tower, the height-to-diameter ratio of which is (4~8):1; the second reaction tower is a zoned temperature-controlled reaction tower, the tower body is divided into an upper cooling zone, a middle contact reaction zone and a lower heating zone from top to bottom, the ratio of the axial length of the upper cooling zone to the axial length of the lower heating zone is (0.5~0.7):1; the temperature of the upper cooling zone is below 60℃, and the temperature of the lower heating zone is 105~120℃.

[0015] Furthermore, the second reaction tower is provided with a second upper support port at the top, a second lower support port at the bottom, and a second middle support port in the middle; the vinyl dimethyl chlorosilane enters the second reaction tower from the second upper support port, the water vapor enters the second reaction tower from the second lower support port, and the reactant exits the second reaction tower from the second middle support port and then enters the second distillation tower.

[0016] Furthermore, the unreacted acetylene in S1 is purified and returned to S1 for recycling, and the unreacted dimethylchlorosilane separated in the first distillation column is returned to S1 for recycling; the vinyl dimethylchlorosilane collected in the first distillation column first enters the first receiving tank, and then flows out of the first receiving tank and enters the second reaction column through the second upper branch port on the second reaction column.

[0017] Furthermore, the hydrogen chloride separated in the second distillation column is reused as a raw material for the synthesis of trichlorosilane.

[0018] More preferably, the interior of the second reaction tower is lined with enamel material. The second reaction tower has a diameter of 30cm, a height of 1.8m, and a volume of 500L. The second reaction tower has zoned temperature control. The upper 50cm section of the tower is cooled by water through a jacket to maintain the temperature below 60℃. The bottom 50cm section is heated with steam to maintain the temperature of the lower section at 105~120℃. The middle 80cm section of the tower is the contact reaction zone. The pressure inside the tower is 0.05~0.1MPa. The top of the second reaction tower is equipped with a hydrogen chloride outlet. A second middle branch is opened 60cm from the top, through which the reaction product enters the second distillation tower. A second lower branch is opened 80cm from the bottom, through which liquid water is discharged when it accumulates to a certain level.

[0019] The beneficial effects of this invention are: This invention provides a method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane that avoids the sodium condensation method. First, vinyldimethylchlorosilane is synthesized via hydrosilylation. Then, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane is synthesized via hydrolysis with steam. This method achieves continuous synthesis, hydrolysis, and distillation, while also allowing for the removal and reuse of excess acetylene. The recovered byproduct hydrogen chloride has a low water content and can be directly used as a raw material for the synthesis of trichlorosilane, avoiding the generation of hydrochloric acid or saline wastewater. Distillation yields 99% pure, low-chloride-ion 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The synthesis process is simple, efficient, and carries low safety risks related to equipment and raw material use and storage. Attached Figure Description

[0020] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the synthesis apparatus used in the preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to the present invention. In the diagram, 1 is a solvent tank, 2 is a preheater, 3 is an acetylene tank, 4 is an acetylene vaporization tank, 5 is a dimethylchlorosilane tank, 6 is a dimethylchlorosilane vaporization tank, 7 is a first reaction tower, 71 is a first upper branch, 72 is a first middle branch, 73 is a first lower branch, 8 is an acetylene purifier, 9 is a first distillation tower, 10 is a first receiving tank, 11 is a pure water storage tank, 12 is a water evaporator, 13 is a second reaction tower, 131 is a second upper branch, 132 is a second lower branch, 133 is a second middle branch, 134 is a hydrogen chloride discharge outlet, 14 is a second distillation tower, 15 is a hydrogen chloride purifier, 16 is a hydrogen chloride receiving tank, 17 is a product receiving tank; 18 is a condenser, and 19 is a non-condensable gas receiving tank. Detailed Implementation

[0022] The technical solution of the present invention will now be clearly and completely described in conjunction with the accompanying drawings.

[0023] like Figure 1As shown, the synthesis apparatus used in the preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane in this invention includes a solvent tank 1, a preheater 2, an acetylene tank 3, an acetylene vaporization tank 4, a dimethylchlorosilane tank 5, a dimethylchlorosilane vaporization tank 6, a first reaction tower 7, an acetylene purifier 8, a first distillation tower 9, a first receiving tank 10, a pure water storage tank 11, a water evaporator 12, a second reaction tower 13, a second distillation tower 14, a hydrogen chloride purifier 15, a hydrogen chloride receiving tank 16, a product receiving tank 17, a condenser 18, and a non-condensable gas receiving tank 19. The solvent material tank 1 is connected to the preheater 2, the acetylene material tank 3 is connected to the acetylene vaporization tank 4, and the dimethylchlorosilane material tank 5 is connected to the dimethylchlorosilane vaporization tank 6. The preheater 2, the acetylene vaporization tank 4, and the dimethylchlorosilane vaporization tank 6 are respectively connected to the first reaction tower 7. The first reaction tower 7 is connected to the first distillation tower 9, the first distillation tower 9 is connected to the acetylene purifier 8, and the acetylene purifier 8 is connected to the acetylene vaporization tank 4. The first distillation tower 9 is connected to the first receiving tank 10, the pure water storage tank 11 is connected to the water evaporator 12, and the first receiving tank 10 and the water evaporator 12 are connected to the second reaction tower 13. The second reaction tower 13 is connected to the second distillation tower 14 and the hydrogen chloride purifier 15, and the hydrogen chloride purifier 15 is connected to the hydrogen chloride receiving tank 16. The distillation outlet of the second distillation tower 14 is connected to the product receiving tank 17, and the condensable gas enters the non-condensable gas receiving tank 19 through the condenser 18.

[0024] The first reaction tower 7 in this apparatus is used to prepare the intermediate product vinyldimethylchlorosilane. The height-to-diameter ratio of the first reaction tower 7 is (3~5):1, and the upper part of the tower body is provided with a first upper support 71 and a first middle support 72 at a position 0.08~0.12 times the tower height from the top of the tower body, and the bottom of the tower body is provided with a first lower support 73. Dimethylchlorosilane gas from dimethylchlorosilane vaporizer 6 and acetylene gas from acetylene vaporizer 4 enter the first reaction tower 7 through the first upper support 71. The first solvent and catalyst in solvent material tank 1 are preheated by preheater 2 and then enter the first reaction tower 7 through the first lower support 73. The synthesis liquid is discharged from the first middle support 72 and then enters the first distillation tower 9.

[0025] Excess unreacted acetylene is purified by acetylene purifier 8 and then enters acetylene vaporization tank 4 for continued recycling as a raw material. Unreacted dimethylchlorosilane separated in the first distillation column 9 enters dimethylchloro material tank 5 for continued recycling as a raw material. Vinyl dimethylchlorosilane collected by distillation in the first distillation column 9 enters the first receiving tank 10.

[0026] In this embodiment of the invention, the first reaction tower 7 is lined with enamel material, has a diameter of 20cm, a height of 80cm, a volume of 100L, a first upper support 71 8cm from the top of the tower, and a first middle support 72 in the middle. The synthesis pressure and pressure temperature inside the tower are 0.2~0.5MPa and 70~90℃, respectively. The content of the first solvent in the synthesis liquid inside the first reaction tower 7 is kept not less than 25%. When the liquid level in the first reaction tower 7 reaches 60cm, the solvent heated by the preheater 2 is added to the first reaction tower through a flow meter.

[0027] This invention regulates the pressure of the first reaction tower 7 by controlling the vaporization temperature of acetylene and dimethylchlorosilane, and controls the material ratio and holding time by controlling the mass flow rates of acetylene, dimethylchlorosilane, and the solvent containing the catalyst. For example, when 20 kg of solvent is pre-filled in the first reaction tower 7, the acetylene flow rate is 10 kg / h, the dimethylchlorosilane flow rate is 5 kg / h, the molar ratio of acetylene to dimethylchlorosilane is 7.9:1, and the residence time of the material in the first reaction tower 7 (100 L volume, 20 cm diameter, 80 cm height) is 4.5-5 h, after a period of reaction discharge, the catalyst is added to maintain the Pt content in the first reaction tower 7 at 5-50 ppm of the mass fraction of dimethylchlorosilane, and to maintain the first solvent content in the synthesis liquid in the first reaction tower 7 at no less than 25%. When the liquid level in the first reaction tower 7 reaches 60 cm, the solvent heated by the preheater 2 is added to the first reaction tower through a flow meter.

[0028] like Figure 1 As shown, the second reaction tower 13 in this apparatus is used to prepare the target product 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The height-to-diameter ratio of the second reaction tower 13 is (4~8):1. It is a zoned temperature-controlled reaction tower. From top to bottom, the tower body consists of an upper cooling zone, a middle contact reaction zone, and a lower heating zone. The ratio of the axial length of the upper cooling zone to the axial length of the lower heating zone is (0.5~0.7):1. The temperature of the upper cooling zone is below 60℃, and the temperature of the lower heating zone is 105~120℃.

[0029] The second reaction tower 13 has a second upper support port 131 at the top, a second lower support port 132 at the bottom, and a second middle support port 133 in the middle. The intermediate product vinyldimethylchlorosilane flows out of the first receiving tank 10 and enters the second reaction tower 13 through the second upper support port 131. Water vapor in the water evaporator 12 enters the second reaction tower 13 through the second lower support port 132. The reaction material is discharged from the second middle support port 133 and enters the second distillation tower 14. Hydrogen chloride enters the hydrogen chloride purifier 15 from the hydrogen chloride discharge port 134 at the top of the second reaction tower 13. After purification, it enters the hydrogen chloride receiving tank 16, where it is reused as a raw material for the synthesis of trichlorosilane. The reaction material is distilled and purified to obtain 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, which enters the product receiving tank 17. The distillation solvent enters the non-condensable gas receiving tank 19 through the condenser 18 and then enters the solvent material tank 1 for recycling.

[0030] In the process of hydrolyzing vinyldimethylchlorosilane with steam, the segmented temperature control of the second reaction tower 13 not only improves efficiency and reduces costs, but also avoids the generation of hydrochloric acid or saline wastewater while simultaneously recovering and utilizing hydrogen chloride. Furthermore, during the reaction, as the hydrolysis product 1,3-divinyl-1,1,3,3-tetramethyldisiloxane flows to the bottom of the tower, the reboiling steam can completely react the incompletely hydrolyzed vinyldimethylchlorosilane in the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane. The higher steam temperature also washes away the dissolved hydrogen chloride from the top of the second reaction tower 13, significantly reducing the acidity of the product and simplifying post-processing steps. High-quality products can be easily obtained through distillation. From the top of the reaction tower, due to the sufficient introduction of chlorosilane, the steam can be completely consumed, and the cooling measures can condense the steam, ensuring that hydrogen chloride enters the hydrogen chloride recovery system in gaseous form, eliminating the need to use water to absorb hydrogen chloride to create a saturated solution, and then evaporate and dry the hydrogen chloride from the saturated solution.

[0031] In this embodiment of the invention, the second reaction tower 13 is lined with enamel, has a diameter of 30cm, a height of 1.8m, and a volume of 500L. The reaction tower features zoned temperature control: the upper 50cm section is cooled by water circulation through a jacket to maintain a temperature below 60℃; the bottom 50cm section is heated with steam to maintain a temperature of 105-120℃; and the middle 80cm section is the contact reaction zone. The internal pressure is 0.05-0.1MPa. The second reaction tower 13 has a hydrogen chloride outlet 134 at the top, a second upper branch 131 60cm from the top, through which the reaction product enters the second distillation tower 14 via the second middle branch 133. A second lower branch 132 80cm from the bottom of the tower discharges liquid water into a water evaporator 12 after reaching a certain level.

[0032] In this invention, water vapor is introduced from the bottom of the enamel-lined second reaction tower 13 at a rate of 10 kg / h via a booster pump through a mass flow meter. The bottom of the second reaction tower 13 is kept at 105~120℃ to maintain the water in a vaporized state and the pressure inside the tower is maintained at 0.05~0.1 MPa. Vinyl dimethyl chlorosilane liquid is introduced from the top of the hydrolysis tower, and the molar ratio of water to vinyl dimethyl chlorosilane is maintained at (5~10):1 by mass flow.

[0033] Using the above-described synthesis apparatus, this invention achieves the continuous production of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane through a continuous hydrosilylation reaction and steam hydrolysis, specifically including the following steps: A certain amount of solvent in solvent tank 1 is heated by preheater 2 and then pumped into the first reaction tower 7, which is preheated to 60-70°C. A catalyst is added, and the dimethylchlorosilane in dimethylchlorosilane tank 5 is vaporized in dimethylchlorosilane vaporization tank 6, while the acetylene in acetylene tank 3 is vaporized in acetylene vaporization tank 4. The vaporized dimethylchlorosilane and acetylene gases simultaneously enter the first reaction tower 7 at certain flow rates, maintaining the pressure in the first reaction tower 7 at 0.2-0.5 MPa. The reaction is carried out at 0~90℃ for 4~6 hours. The material enters the first distillation column 9 from the first upper branch 71 of the first reaction column 7 to separate vinyl dimethyl chlorosilane. The collected vinyl dimethyl chlorosilane is fed from the top of the second reaction column 13 and reacts with the water vapor entering from the bottom of the second reaction column 13 in the middle section of the second reaction column 13. The pressure of the second reaction column 13 is maintained at 0.05~0.1MPa. 1,3-Divinyl-1,1,3,3-tetramethyldisiloxane is obtained by distillation.

[0034] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to specific embodiments. All mentioned embodiments are implemented based on the technical solutions of this invention, and detailed implementation processes are provided. However, it should be stated that the scope of protection of this invention is not limited to the following embodiments. Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; the materials and reagents used, unless otherwise specified, are commercially available.

[0035] Example 1

[0036] The preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane follows these steps: (1) 15 kg of xylene preheated to 60°C was introduced into the first reaction tower. The first reaction tower was heated to 60°C and the pressure was maintained at 0.095~1 MPa. Acetylene gas was introduced into the first reaction tower with a volume of 100 L, a diameter of 20 cm and a height of 80 m at a flow rate of 10 kg / h and dimethylchlorosilane gas was introduced into the first reaction tower with a flow rate of 6 kg / h. A catalyst was added to maintain Pt at 10~20 ppm of dimethylchlorosilane. The pressure in the first reaction tower was 0.25~0.3 MPa. When the liquid level in the first reaction tower reached 60 cm, the solvent heated by the preheater was added to the first reaction tower through the flow meter to maintain the solvent ratio at 25%~35%. The material entered the first distillation tower through the upper branch 8 cm away from the top of the first reaction tower. Vinyl dimethylchlorosilane was collected by distillation. After 3 days of feeding, 453.3 kg of vinyl dimethylchlorosilane with a content of 99.5% was collected by rectification, with a yield of 82.3%.

[0037] The catalyst preparation steps are as follows: Under nitrogen protection, 0.2 kg of xylene was heated to 60 °C, and 0.22 kg of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane was added. 27 g of chloroplatinic acid was added to 750 ml of isopropanol solution, and the mixture was heated to 100-105 °C and reacted for 2 hours. The mixture was then cooled to below 60 °C, and 50 g of sodium bicarbonate and 50 g of anhydrous magnesium sulfate were added for neutralization and drying for 1 hour. The mixture was then filtered to obtain the final product.

[0038] Steam was heated to 150°C and fed into a second reaction column with a volume of 500L, a diameter of 30cm, and a height of 180cm at a flow rate of 10kg / h. Steam heating was used to maintain the temperature of the lower section (bottom 80cm) at 115-120°C, and the pressure inside the column was 0.095-0.1MPa. Simultaneously, distilled vinyldimethylchlorosilane was added from the top of the second reaction column at a flow rate of 10kg / h. Water was circulated through a jacket to cool the upper 50cm section, maintaining the temperature at 45-50°C. When the reactant reached a level 60cm from the top of the second reaction column, it was discharged into a second distillation column. When the water level exceeded a level 80cm from the bottom of the second reaction column, water was drained into a water evaporator. After continuous feeding for 2 days, 335.1kg of [amount missing] was collected at 102°C and -0.06 to -0.05MPa in the second distillation column. 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with a purity of 99.1% and a chloride ion content of 3.23 ppm was obtained in a yield of 95.7%.

[0039] Example 2

[0040] The difference between this embodiment and Embodiment 1 is that: In step (1), the flow rate of acetylene gas was 12 kg / h, and the flow rate of dimethylchlorosilane gas was 6 kg / h; Pt was 20-30 ppm of dimethylchlorosilane. After 3 days of feeding, 455.5 kg of vinyldimethylchlorosilane with a purity of 99.23% was collected by distillation, with a yield of 82.7%.

[0041] In step (2), the flow rates of water and vinyldimethylchlorosilane were 15 kg / h and 12 kg / h, respectively; the bottom temperature of the second reaction tower was maintained at 105~110℃, and the pressure was 0.08~0.09 MPa. After 2 days of feeding, 419.2 kg of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane with 99.24% chloride content and 4.37 ppm chloride ions was collected by distillation, with a yield of 94.2%.

[0042] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. A method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, characterized in that, Includes the following steps: S1, Preparation of vinyldimethylchlorosilane: Dimethylchlorosilane gas and acetylene gas are simultaneously added to the first solvent at 60~70℃. Under the action of a catalyst, the reaction is carried out at 0.2~0.5MPa and 70~90℃ for 4~6h to obtain a synthesis solution. The synthesis solution is then distilled to obtain vinyldimethylchlorosilane. S2, Preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane: The vinyl dimethyl chlorosilane described in S1 is mixed with water vapor and subjected to hydrolysis reaction under controlled temperature and partitioned pressure of 0.05~0.1 MPa to obtain a reaction material. The reaction material is then distilled to obtain the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane.

2. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 1, characterized in that, The molar ratio of acetylene gas to dimethylchlorosilane gas in S1 is (5~12):1; the content of the first solvent in the synthesis solution is not less than 25%, and the first solvent includes xylene, toluene or tetrahydrofuran; the catalyst is a platinum compound, and the content of Pt in the synthesis solution is 5~50 ppm of the mass fraction of dimethylchlorosilane.

3. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 2, characterized in that, The platinum compound is prepared as follows: under nitrogen protection, the second solvent is heated to 60±2℃, an auxiliary agent is added, an isopropanol solution of chloroplatinic acid hexahydrate is added, the temperature is raised to 100~105℃ and kept at the temperature for 1.5~2.5h, the temperature is lowered to below 60℃, a neutralizing agent is added sequentially for neutralization, a desiccant is added for drying, and the product is obtained by filtration.

4. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 3, characterized in that, The additives include 1,3-divinyltetramethyldisiloxane, tetramethyltetravinylcyclotetrasiloxane, vinyltrimethoxysilane, vinyltriethoxysilane, vinylsilane hydrolysate oligomers, or have a viscosity of 20-50 mm. 2 / s, vinyl silicone oil with a vinyl content >2%; the second solvent is consistent with the first solvent; the neutralizing agent includes sodium bicarbonate, and the drying agent includes anhydrous magnesium sulfate.

5. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 1, characterized in that, The molar ratio of water vapor to vinyldimethylchlorosilane in S2 is (5~10):

1.

6. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 1, characterized in that, The preparation of vinyldimethylchlorosilane described in S1 is carried out in a first reaction tower. The height-to-diameter ratio of the first reaction tower is (3~5):1, and a first upper support and a first middle support are provided at a position 0.08~0.12 times the tower height from the top of the tower. A first lower support is provided at the bottom of the tower. The dimethylchlorosilane gas and acetylene gas enter the first reaction tower from the first upper support, the first solvent and catalyst enter the first reaction tower from the first lower support, and the synthesis liquid exits the first reaction tower from the first middle support and then enters the first distillation tower.

7. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 6, characterized in that, The preparation of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane as described in S2 is carried out in a second reaction tower with a height-to-diameter ratio of (4~8):

1. The second reaction tower is a zoned temperature-controlled reaction tower, with the tower body consisting of an upper cooling zone, a middle contact reaction zone, and a lower heating zone from top to bottom. The ratio of the axial length of the upper cooling zone to the axial length of the lower heating zone is (0.5~0.7):

1. The temperature of the upper cooling zone is below 60°C, and the temperature of the lower heating zone is 105~120°C.

8. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 7, characterized in that, The second reaction tower has a second upper support port at the top, a second lower support port at the bottom, and a second middle support port in the middle. The vinyl dimethyl chlorosilane enters the second reaction tower from the second upper support port, the water vapor enters the second reaction tower from the second lower support port, and the reactant exits the second reaction tower from the second middle support port and then enters the second distillation tower.

9. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 8, characterized in that, Unreacted acetylene in S1 is purified and returned to S1 for recycling. Unreacted dimethylchlorosilane separated in the first distillation column is also returned to S1 for recycling. Vinyl dimethylchlorosilane collected in the first distillation column first enters the first receiving tank, and then flows out of the first receiving tank and enters the second reaction column through the second upper branch port.

10. The method for preparing 1,3-divinyl-1,1,3,3-tetramethyldisiloxane according to claim 8, characterized in that, The hydrogen chloride separated in the second distillation column is reused as a raw material for the synthesis of trichlorosilane.

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