Preparation method of branched tetrasiloxane
By using hydrogen-containing trisiloxane, water, acetic acid and organic amines in the preparation of branched chain tetrasiloxanes, the problems of complex reactions and complex product structures in the prior art are solved, and the problem of achieving the following is achieved High-efficiency, low-energy consumption branched chain tetrasiloxane synthesis, with a yield of more than 97%, simplifying the process flow and reducing costs.
Patent Information
- Application Number
- CN202411353882.X
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-27
- Publication Date
- 2024-12-13
- Estimated Expiration
- 2044-09-27
AI Technical Summary
The existing branched chain tetrasiloxane preparation methods have problems such as complex reaction process, requiring excessive trimethylchlorosilane or hexamethyldisiloxane, and complex product structure, resulting in high industrialization costs and low yields.
The reaction is carried out under disilazane catalyzed by hydrogen-containing trisiloxane, water, acetic acid, N,N-dimethylformamide and organic amine. The reaction rate is increased and impurities is suppressed through the co-catalysis of acetic acid and organic amine. Generate to achieve efficient synthesis of branched tetrasiloxane.
It has achieved efficient preparation of branched tetrasiloxane, with a yield of more than 97%, low separation energy consumption, no need for a large amount of trimethylchlorosilane or hexamethyldisiloxane, simple process and high purity of the product.
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Figure CN118878573B_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the technical field of siloxanes, and in particular to a method for preparing branched tetrasiloxane. Background Art
[0002] Since small-molecule branched siloxanes do not have D linkages (dimethylsiloxy linkages), they will not decompose to produce small-molecule cyclosiloxane compounds during subsequent use. They have very high stability and can be used in cosmetics, high and low temperature resistant thermal conductive fluids, and raw materials for electronic materials, etc. The traditional method for preparing branched siloxanes is to use methyltrimethoxysilane or methyltrichlorosilane to co-hydrolyze hexamethyldisiloxane or trimethylchlorosilane. Since the reaction rates of methyltrimethoxysilane and methyltrichlorosilane are faster, in order to increase the yield and reduce the production of high molecular weight cross-linked byproducts, the amount of hexamethyldisiloxane or trimethylchlorosilane used is much greater than the theoretical amount.
[0003] Chinese invention patent CN107207949B discloses branched organic siloxane used as a heat transfer fluid. Although this invention patent successfully prepares branched siloxane with excellent high temperature resistance, the reaction process is complicated and has extremely high requirements. It requires argon gas protection and the use of multiple organic solvents in the process, and the industrialization cost is relatively high.
[0004] European invention patent EP1241171A1 discloses a method for preparing branched tetrasiloxane, in which trimethylsilyl chloride and hexamethyldisiloxane are reacted under the catalysis of chlorophosphazene to obtain a branched tetrasiloxane product, in which the hexamethyldisiloxane used is greatly excessive, and the yield of methyltris(trimethylsiloxy)silane is less than 70%, and a large amount of trimethylsilyl chloride is produced in the system.
[0005] In summary, the current preparation method of branched tetrasiloxane has the disadvantages of complex reaction process, the need to use a large amount of trimethylchlorosilane or hexamethyldisiloxane to improve the conversion rate, and the complex structure of the final product. It is urgent to develop a new preparation method of branched tetrasiloxane to solve the above problems. Summary of the invention
[0006] The technical problem to be solved by the present invention is: to overcome the shortcomings of the prior art and provide a method for preparing branched tetrasiloxane, which can accurately synthesize branched tetrasiloxane and can achieve a yield of more than 97% without excessive trimethylchlorosilane or hexamethyldisiloxane, and has low separation energy consumption.
[0007] The technical solution of the present invention is:
[0008] The preparation method of branched tetrasiloxane comprises the following steps: adding hydrogen-containing trisiloxane, water, acetic acid, N,N-dimethylformamide and organic amine into a reaction kettle, dropping disilazane to react at 70-90°C, and washing the product with deionized water after the reaction to obtain branched tetrasiloxane; wherein the amount of acetic acid added is 0.1-1wt.% of the amount of water added, the mass ratio of N,N-dimethylformamide to disilazane is ≥0.2, and the mass of the organic amine accounts for 0.5-5% of the total mass of hydrogen-containing trisiloxane and disilazane.
[0009] Acetic acid, as a catalyst, can increase the reaction rate of water, disilazane and hydrogen-containing trisiloxane; the role of N,N-dimethylformamide is to enhance the compatibility of water with disilazane and hydrogen-containing trisiloxane, ensure the reaction rate and inhibit the generation of impurities such as hexamethyldisiloxane. The reaction temperature is 70-90℃. If the reaction temperature is too low, the reaction rate will be too slow and the content of impurities in the product will increase; if the reaction temperature is too high, disilazane will decompose, the reaction will be violent, and it will cause danger.
[0010] Preferably, the structural formula of the branched tetrasiloxane is as follows: , where R 1 is methyl or vinyl, R 2 It is a hydrocarbon group of 1 to 6 carbon atoms.
[0011] Preferably, the structural formula of the hydrogen-containing trisiloxane is as follows: , where R 1 Methyl or vinyl.
[0012] Preferably, the structural formula of the disilazane is as follows: , R 2 It is a hydrocarbon group of 1 to 6 carbon atoms.
[0013] The synthetic route of branched tetrasiloxane is as follows:
[0014] .
[0015] Preferably, the molar ratio of the hydrogen-containing trisiloxane, water and disilazane is (1.8-2): (2-3): 1. Excessive water will cause phase separation of the system and reduce the reaction rate.
[0016] Preferably, the organic amine is diethylhydroxylamine, which has very good compatibility with the system. Meanwhile, diethylhydroxylamine, as a catalyst, can enhance the reaction rate of water, disilazane and hydrogen-containing trisiloxane.
[0017] Compared with the prior art, the present invention has the following beneficial effects:
[0018] The preparation method of the branched tetrasiloxane of the present invention comprises the following steps: hydrogen-containing trisiloxane, water and disilazane react under the co-catalytic action of acetic acid and an organic amine to prepare the branched tetrasiloxane product, and the process is simple; and compared with the traditional preparation process, the method of the present invention has a fast reaction speed, does not require a large amount of trimethylchlorosilane or hexamethyldisiloxane to ensure the yield of the target product, and the yield of the method of the present invention can reach more than 97%, and the purification energy consumption is low. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 is the methyl tris(trimethylsiloxy)silane obtained in Example 1 of the present invention 1 H NMR spectrum.
[0020] Figure 2 3-trimethylsilyloxy-1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane prepared in Example 2 of the present invention 1 H NMR spectrum.
[0021] Figure 3 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane prepared in Example 3 of the present invention 1 H NMR spectrum.
[0022] Figure 4 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane prepared in Example 3 of the present invention 29 Si NMR spectrum.
[0023] Figure 5 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane prepared in Example 3 of the present invention 13 C NMR spectrum.
[0024] Figure 6 3-n-hexyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane prepared in Example 4 of the present invention 1 H NMR spectrum. DETAILED DESCRIPTION
[0025] In order to enable persons skilled in the art to better understand the technical solution of the present invention, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention.
[0026] Unless otherwise specified, all raw materials used in the following examples are commercially available products.
[0027] Example 1 Preparation of methyltris(trimethylsiloxy)silane
[0028] The structural formula of methyltris(trimethylsiloxy)silane is as follows:
[0029] .
[0030] Its synthetic route is as follows:
[0031] .
[0032] The preparation method is as follows: 445.02 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 54 g of deionized water, 32.28 g of N,N-dimethylformamide, 30.32 g of diethylhydroxylamine, and 0.38 g of glacial acetic acid are added to a flask, stirring is started, the temperature is raised to 70°C, 161.4 g of hexamethyldisilazane is added dropwise to the flask, the temperature is kept at 70°C, and the reaction is continued for 2 hours after the addition is completed, and the product is washed three times with deionized water, and small molecular impurities are removed at -0.095 MPa and 80°C to obtain 615.49 g of colorless transparent liquid, of which the purity of methyltris(trimethylsiloxy)silane is 98.15%, and the yield is 97.22%. 1 The product was characterized by H NMR. Figure 1 As shown, 1 H NMR (400 MHz, CDCl 3 , ppm): 0.19 (s, 3H), 0.21 (s, 27H).
[0033] Example 2 Preparation of 3-trimethylsilyloxy-1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane
[0034] The structural formula of 3-trimethylsilyloxy-1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane is as follows:
[0035] .
[0036] Its synthetic route is as follows:
[0037] .
[0038] The synthetic route of 1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane is as follows:
[0039] .
[0040] The preparation method is as follows: 932 g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane, 60.13 g of 1,3,5,7-tetramethylcyclotetrasiloxane and 29.76 g of concentrated sulfuric acid are added into a flask, stirring is started, the reaction is carried out for 4 hours, 160.95 g of sodium carbonate is added for neutralization, after the neutralization is completed, the salt is filtered out, distillation is performed, and the 46-48°C fraction under 970 Pa is collected to obtain 209.55 g of the target product.
[0041] The preparation method of 3-trimethylsilyloxy-1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane is as follows: 443.75 g of 1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane, 36 g of deionized water, 64.56 g of N,N-dimethylformamide, 3.03 g of diethylhydroxylamine, and 0.36 g of glacial acetic acid are added to a flask, stirring is started, the temperature is raised to 80°C, 161.4 g of hexamethyldisilazane is added dropwise to the flask, the temperature is kept at 80°C, and the reaction is continued for 2 hours after the addition is completed, and the product is washed three times with deionized water. Small molecular impurities are removed at -0.095 MPa and 80°C to obtain 597.06 g of colorless transparent liquid, of which the purity of 3-trimethylsilyloxy-1,3-divinyl-1,1,3,5,5-pentamethyltrisiloxane is 99%, and the yield is 98.11%. 1 The product was characterized by H NMR. Figure 2 As shown, 1 H NMR (400 MHz, CDCl 3 , ppm): 0.14 (s, 3H), 0.19 (s, 9H), 0.21 (s, 12H), 5.73 (dd, J1=20.4Hz, J2=4.4Hz, 2H), 5.93 (dd, J1=15.1Hz, J2=3.7Hz, 2H), 6.12 (dd, J1=20.4Hz, J2=15.1Hz, 2H).
[0042] Example 3 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0043] The structural formula of vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane is as follows: .
[0044] Its synthetic route is as follows:
[0045] .
[0046] The preparation method is as follows: add 422.77 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 37.1 g of N,N-dimethylformamide, 18.25 g of diethylhydroxylamine, and 0.046 g of glacial acetic acid into a flask, start stirring, raise the temperature to 90°C, drop 1,3-divinyl-1,1,3,3-tetramethyldisilazane into the flask, keep the temperature at 90°C, continue the reaction for 2 hours after the addition is completed, wash three times with deionized water, remove small molecular impurities at -0.095 MPa and 80°C, and obtain 610.06 g of colorless transparent liquid, of which the purity of 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane is 97.89%, and the yield is 97.40%. 1 H NMR, 29 Si NMR and 13 The product was characterized by C NMR. Figure 3-5 As shown:
[0047] 1 H NMR (400 MHz, CDCl 3 , ppm): 0.14 (s, 3H), 0.19 (s, 18H), 0.21 (s, 6H), 5.73 (dd, J1=20.4Hz, J2=4.4Hz, 1H), 5.93 (dd, J1=15.1Hz, J2=3.7Hz, 1H), 6.12 (dd, J1=20.4Hz, J2=15.1Hz, 1H).
[0048] 13 C NMR (400 MHz, CDCl 3 , ppm): -2.12 (1C), 0.15 (2C), 1.67 (6C), 131.67 (1C), 139.23 (1C).
[0049] 29 Si NMR (400 MHz, CDCl 3 , ppm): 7.52 (2Si), -4.08 (1Si), -64.21 (1Si).
[0050] Example 4 Preparation of 3-n-hexyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0051] The structural formula of 3-n-hexyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane is as follows:
[0052] .
[0053] Its synthetic route is as follows:
[0054] .
[0055] Among them, the preparation method of 1,3-dihexyl-1,1,3,3-tetramethyldisilazane is as follows: 168.32g of 1-hexene and 10.72g of platinum-carbon catalyst (platinum content is 5wt.%) are added to a flask and stirred, the temperature is raised to 40°C, 189.22g of dimethylhydrochlorosilane is added dropwise to the flask, after the reaction is completed, the platinum-carbon catalyst is removed by filtering, and the product is n-hexyldimethylchlorosilane. The temperature is lowered to 0°C, ammonia is directly introduced into the above reaction solution, the amount of ammonia introduced is controlled, and the reaction temperature is controlled not to exceed 10°C. After the ammonia introduction is completed, it is washed three times with deionized water, and the liquid is separated to obtain 1,3-di-n-hexyl-1,1,3,3-tetramethyldisilazane.
[0056] The preparation method of 3-n-hexyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane is as follows: 445.02 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 90.5 g of N,N-dimethylformamide, 37.33 g of diethylhydroxylamine, and 0.45 g of glacial acetic acid are added into a flask, stirring is started, the temperature is raised to 80°C, and 1,3-di-n-hexyl-1,1 ,3,3-tetramethyldisilazane 301.67g was added dropwise to the flask, the temperature was kept at 80℃, the reaction was continued for 2h after the addition was completed, and the small molecule impurities were removed at -0.095MPa and 80℃ to obtain 766.59g of colorless transparent liquid, of which the purity of 3-n-hexyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane was 98.46% and the yield was 99.1%. 1 The product was characterized by H NMR. Figure 6 As shown, 1 H NMR (400 MHz, CDCl 3 , ppm): 0.14 (s, 3H), 0.19 (s, 18H), 0.21 (s, 6H), 0.54 (t, J=8.32Hz, 2H), 0.88 (t, J=7.1Hz, 3H), 1.31 (m, 8H).
[0057] Comparative Example 1 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0058] 422.77 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 37.1 g of N,N-dimethylformamide, 18.25 g of diethylhydroxylamine and 0.046 g of glacial acetic acid were added into a flask, stirring was started, the temperature was raised to 100°C, 185.42 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane was added dropwise into the flask, the system temperature was maintained at 100°C, the reaction was continued for 2 h after the addition was completed, and the mixture was washed three times with deionized water. Small molecular impurities were removed at -0.095 MPa and 80°C to obtain 279.33 g of colorless transparent liquid, of which the purity of 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane was 74.33%, and the yield was 32.17%.
[0059] Comparative Example 2 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0060] 422.77 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 37.1 g of N,N-dimethylformamide, 18.25 g of diethylhydroxylamine and 0.036 g of glacial acetic acid were added into a flask, stirring was started, the temperature was raised to 90°C, 185.42 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane was added dropwise into the flask, the system temperature was maintained at 90°C, the reaction was continued for 2 h after the addition was completed, the product was washed three times with deionized water, small molecular impurities were removed at -0.095 MPa and 80°C, and 430.5 g of colorless transparent liquid was obtained, wherein the purity of 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane was 36.55%, and the yield was 24.38%.
[0061] Comparative Example 3 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0062] 422.77 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 33.37 g of N,N-dimethylformamide, 18.25 g of diethylhydroxylamine, and 0.046 g of glacial acetic acid were added to the flask, stirring was started, and the temperature was raised to 90°C. 185.42 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane was added dropwise to the flask, and the system temperature was maintained at 90°C. When the addition began, the system The system was separated into layers. When half of the addition was completed, the system began to react and the temperature rose sharply to 100°C. After the addition was completed, the reaction was continued for 2 hours. The product was washed three times with deionized water and small molecular impurities were removed at -0.095 MPa and 80°C to obtain 557.16 g of colorless transparent liquid, of which 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane had a purity of 37.45% and a yield of 32.33%.
[0063] Comparative Example 4 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0064] Add 422.77 g of 1,1,1,3,5,5,5-heptamethyltrisiloxane, 45 g of deionized water, 37.1 g of N,N-dimethylformamide, 2.43 g of diethylhydroxylamine and 0.046 g of glacial acetic acid into a flask, start stirring, raise the temperature to 90°C, add 185.42 g of 1,3-divinyl-1,1,3,3-tetramethyldisilazane dropwise into the flask, maintain the system temperature at 90°C, continue the reaction for 2 h after the addition is completed, wash three times with deionized water, remove small molecular impurities at -0.095 MPa and 80°C, and no product remains.
[0065] Comparative Example 5 Preparation of 3-vinyldimethylsilyloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane
[0066] 149.47 g of methyltrichlorosilane, 405.95 g of hexamethyldisiloxane and 186.4 g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane were added to a flask, and 7.42 g of phosphazene chloride was added to the flask. Stirring was started and the temperature was raised to 80°C for reaction. After the reaction was carried out for 5 hours, samples were taken for GC analysis. The content of the target product 3-vinyldimethylsiloxy-1,1,1,3,5,5,5-heptamethyltrisiloxane was 22.35%.
Claims
1. A method for preparing branched tetrasiloxane, characterized in that: Add hydrogen-containing trisiloxane, water, acetic acid, N,N-dimethylformamide and organic amine into a reaction kettle, add disilazane dropwise and react at 70-90°C, wash the product with deionized water after the reaction to obtain branched tetrasiloxane; wherein, the amount of acetic acid added is 0.1-1wt.% of the amount of water added, the mass ratio of N,N-dimethylformamide to disilazane is ≥0.2, and the mass of the organic amine accounts for 0.5-5% of the total mass of hydrogen-containing trisiloxane and disilazane; The structural formula of the branched tetrasiloxane is as follows: , where R 1 is methyl or vinyl, R 2 is a hydrocarbon group of 1 to 6 carbon atoms; The structural formula of the hydrogen-containing trisiloxane is as follows: , where R 1 is methyl or vinyl; The structural formula of the disilazane is as follows: , R 2 is a hydrocarbon group of 1 to 6 carbon atoms; The organic amine is diethylhydroxylamine.
2. The method for preparing branched tetrasiloxane according to claim 1, characterized in that: The molar ratio of the hydrogen-containing trisiloxane, water and disilazane is (1.8-2): (2-3): 1.