A method for preparing 2,5-disil-1-oxolane compounds

Abstract

This invention belongs to the field of silane reagent preparation technology, specifically relating to a method for preparing 2,5-disil-1-oxacyclopentane compounds. The preparation method includes the following steps: S1, under nitrogen protection and stirring, a first solvent, dialkylchlorosilane, and a first catalyst are mixed and kept at 50-60°C for 0.5-1 h. Acetylene is slowly introduced into the mixture. After stopping the acetylene introduction, the temperature is raised to 70-80°C and the reaction is maintained for 2-3 h. After distillation to remove impurities, 1,2-bis(chlorodialkylsilyl)ethane is obtained; S2, under stirring, the product obtained in S1 is added dropwise to an ammonia solution at 10-20°C for hydrolysis, separation, neutralization, and drying to obtain a mixture of cyclic and linear siloxanes; S3, the substance obtained in S2 is mixed with a second solvent and a second catalyst and heated at -0.07--0.06 MPa and 120-130°C for distillation to obtain the final product. The preparation method provided by this invention has mild reaction conditions, low cost, and a yield of over 70%, making it suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of silane reagent preparation technology, specifically relating to a method for preparing 2,5-disil-1-oxacyclopentane compounds. Background Technology

[0002] 2,5-Disil-1-oxacyclopentanes are a class of five-membered heterocyclic compounds containing two silicon atoms and one oxygen atom, with a basic skeleton of Si-O-Si-CC. Derivatives of this class, especially high-purity silane heterocyclic compounds such as 2,2,5,5-tetramethyl-1-oxa-2,5-disil-oxacyclopentane, can be used to prepare polydimethylsilylmethylene siloxanes through acid-catalyzed ring-opening. These polydimethylsilylmethylene siloxanes can replace conventional polydimethylsiloxanes, providing high compatibility and selective permeability in pervaporation membrane materials. Furthermore, the resulting polymers, due to their unique biocompatibility, are increasingly being developed for use in transdermal drug delivery systems and biomedical materials such as contact lenses. In addition, polymers containing active silyl ethylene can effectively prevent the permeation of oxygen and sulfur vapors, and possess excellent electrical insulation properties, protecting electronic components, electrodes, and chips from oxidation while improving the material's arc resistance.

[0003] No publicly available information directly reports a synthetic method for 2,2,5,5-tetramethyl-1-oxa-2,5-disiloxane. Based on the principles of organic compounding and related research, the literature indicates that the most promising synthetic route is to first prepare 1,2-bis(hydroxydimethylsilyl)ethane, and then achieve cyclization by controlling the intramolecular condensation reaction. At the same time, by precisely controlling the hydrolysis and condensation conditions of hydroxysilane, the generation of linear and polymeric compounds can be suppressed to improve the yield of five-membered siloxane. However, 1,2-bis(hydroxydimethylsilyl)ethane has poor storage stability and is extremely prone to cyclization and condensation, resulting in low yields of 2,2,5,5-tetramethyl-1-oxa-2,5-disiloxane prepared using this method.

[0004] Therefore, developing new synthetic strategies or improving existing cyclization processes has become an important research direction for breaking through the bottleneck in the preparation of this type of 2,5-disil-1-oxacyclopentane compounds. Summary of the Invention

[0005] Based on this, the purpose of the present invention is to provide a method for preparing 2,5-disil-1-oxacyclopentane compounds, which has mild reaction conditions, low cost, high yield, and is suitable for industrial production.

[0006] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a method for preparing 2,5-disil-1-oxacyclopentane compounds, comprising the following steps: S1, under inert gas protection and stirring, dialkylchlorosilane, the first solvent and the first catalyst are mixed and acetylene is introduced to carry out a hydrosilylation reaction. After the reaction is completed, 1,2-bis(chlorodialkylsilyl)ethane is obtained by distillation to remove impurities. S2, under stirring, an alkaline solution is added to the 1,2-bis(chlorodialkylsilyl)ethane described in S1, and after hydrolysis, separation, neutralization and drying, a mixture of siloxane cyclic and linear is obtained; S3, the siloxane cyclic mixture obtained in S2 is mixed with the linear mixture, the second solvent and the second catalyst, and then subjected to reduced pressure heating distillation to obtain the 2,5-disil-1-oxacyclopentane derivative.

[0007] Furthermore, the inert gas includes nitrogen; the substances removed by distillation include unreacted raw material dialkylchlorosilane, co-product vinyldialkylchlorosilane, and other low-boiling-point impurities; the distillation temperature is 85~90℃ at atmospheric pressure.

[0008] Furthermore, the structural formula of the dialkylchlorosilane in S1 is as follows: R1 and R2 are each independently selected from alkyl groups having 1 to 4 carbon atoms; R1 and R2 are preferably methyl groups.

[0009] Furthermore, in S1, the first solvent is an inert solvent with a boiling point significantly higher than that of dialkylchlorosilane; the first solvent includes toluene, xylene, isooctane or dodecane, preferably dodecane; the amount of the first solvent is 100-200% of the mass of the dialkylchlorosilane.

[0010] Further, in S1, the first catalyst is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum catalyst. The 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum catalyst is prepared by dissolving chloroplatinic acid hexahydrate in 1,3-divinyltetramethyldisiloxane and isopropanol under inert gas protection, heating at 70-80°C for 1.5-2.5 h, followed by cooling and filtration, and then adding N,N-dimethylaniline to the filtrate. The Pt content in the first catalyst is 3-30 ppm of the mass of the dialkylchlorosilane.

[0011] More preferably, the preparation process of the 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum catalyst is as follows: under nitrogen protection, 1g of chloroplatinic acid hexahydrate is dissolved in 5g of 1,3-divinyltetramethyldisiloxane and 10ml of isopropanol, heated at 70~80℃ for 2h, cooled and filtered, and 0.3g of N,N-dimethylaniline is added to obtain the catalyst.

[0012] Furthermore, the molar ratio of acetylene to dimethylchlorosilane in S1 is (0.5~1.2):1.

[0013] Furthermore, in S1, the dialkylchlorosilane, the first solvent, and the first catalyst are mixed and kept at 50-60°C for 0.5-1 h; the hydrosilylation reaction is carried out at 70-80°C for 2-3 h.

[0014] Further, the alkaline solution in S2 includes an ammonia solution with a mass concentration of 5-10%; the molar ratio of ammonia to dialkylchlorosilane in the alkaline solution is (1-1.3):1; the hydrolysis reaction is carried out at a temperature of 10-20°C for 0.5-2 hours.

[0015] Furthermore, the separation, neutralization, and drying steps described in S2 are commonly used methods in the chemical industry. Specifically, the separation involves allowing the mixture to stand at room temperature (25±5℃) for 25-35 minutes; the neutralization involves adding 10% of an inorganic alkali such as sodium carbonate, sodium bicarbonate, or sodium hydroxide to the upper layer obtained after separation to neutralize it to a pH of 5.0-6.5; and the drying process involves heating at -0.04 to -0.03 MPa and 70-80℃ to remove water.

[0016] Further, in S3, the second solvent is a high-boiling-point inert solvent; the second solvent includes n-octadecyl alcohol, n-hexadecyl alcohol, white oil, paraffin oil or dibutyl phthalate, preferably n-octadecyl alcohol; the amount of the second solvent is 30-80% of the mass of the dialkylchlorosilane.

[0017] Further, in S3, the second catalyst includes tetramethylammonium hydroxide, a complex of tetramethylammonium hydroxide with dimethyl silicone oil and tetramethylcyclotetrasiloxane, potassium hydroxide or lithium hydroxide, preferably potassium hydroxide; the amount of the second catalyst is 0.8 to 2% of the mass of the dialkylchlorosilane.

[0018] Furthermore, the pressure for depressurization heating described in S3 is -0.07 to -0.06 MPa, and the temperature is 120 to 130°C.

[0019] The key to the preparation method of 2,5-disil-1-oxacyclopentane compounds in this invention lies in controlling the selectivity of the monoaddition reaction between acetylene and dialkylchlorosilane, and the cyclization under basic conditions to construct a five-membered disiloxane. This reaction is mainly driven by the alkyne structure, the activity of the silane-hydrogen bond, and the cyclization strain; alkyl substitution on the silicon (C1-C4) has no essential impact on the reaction mechanism and feasibility. Based on the reaction pathway and examples disclosed in this invention, those skilled in the art can, without inventive effort, replace dimethylchlorosilane with homologues such as diethyl, dipropyl, and dibutyl to prepare the corresponding 2,5-disil-1-oxacyclopentane derivatives under the same process conditions.

[0020] The beneficial effects of this invention are: This invention provides a method for preparing 2,5-disil-1-oxacyclopentane compounds. The preferred method uses dimethylchlorosilane and acetylene as raw materials to efficiently synthesize disiloxacyclopentane. This synthesis method does not require the prior preparation of highly reactive 1,2-bis(hydroxydimethylsilyl)ethane, has mild synthesis conditions, a single-pass cracking yield of over 70%, a GC content of over 98%, low cost, and is suitable for industrial production. Attached Figure Description

[0021] 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.

[0022] Figure 1 The 2,2,5,5-tetramethyl-2,5-disil-1-oxacyclopentane prepared in Example 1 of this invention 1 H NMR spectrum. Detailed Implementation

[0023] The specific embodiments of the present invention will be described in further detail below with reference to the examples. These examples are for illustrative purposes only and are not intended to limit the scope of the invention.

[0024] Unless otherwise specified in the embodiments of this invention, the conditions shall be performed according to conventional conditions or the manufacturer's recommendations. Reagents or instruments used, unless otherwise specified, are all commercially available conventional products. In this invention, commercially available 92.3% purity dimethylchlorosilane is used as the raw material, and Karl Fischer reagent is used to test for moisture content. Unless otherwise specified, "%" refers to mass percentage, and the yield is calculated based on dimethylchlorosilane.

[0025] Example 1

[0026] The preparation of 2,2,5,5-tetramethyl-2,5-disil-1-oxacyclopentane includes the following steps: S1: Under nitrogen protection and stirring, a mixture of 130g dodecane, 102.5g dimethylchlorosilane, and the first catalyst was kept at 53℃ for 0.5h, where Pt was 10ppm of the mass of dimethylchlorosilane. Acetylene was introduced into the mixture at a rate of 5L / h for 3h40min. After stopping the acetylene introduction, the temperature was raised to 75℃ and the reaction was maintained for 2.5h. The raw material dimethylchlorosilane, the co-product vinyldimethylchlorosilane, and other low-boiling-point impurities were removed by distillation, yielding 221.7g of a colorless to pale yellow transparent liquid.

[0027] The first catalyst used in this step is 1,3-divinyl-1,1,3,3-tetramethyldisiloxane combined with a platinum catalyst. The preparation process is as follows: under nitrogen protection, 1g of chloroplatinic acid hexahydrate is dissolved in 5g of 1,3-divinyl-1,1,3,3-tetramethyldisiloxane and 10ml of isopropanol, heated at 70~80℃ for 2h, cooled and filtered, and 0.3g of N,N-dimethylaniline is added to obtain the catalyst.

[0028] S2: The product obtained in S1 was added dropwise to 255g of 8% ammonia solution at about 12℃, and the dropping temperature was maintained below 20℃. After the addition was complete, the mixture was allowed to stand for 0.5h and then separated. The upper layer was taken and neutralized with 10% sodium carbonate solution to pH=6.2. The mixture was separated again, and the upper layer was taken and heated at about 75℃ and pressure of -0.04~-0.03MPa until no obvious bubbles were generated, resulting in 210.8g of slightly turbid colorless liquid with a water content of 368ppm.

[0029] S3: In a 250ml three-necked flask, the product obtained in S2 was mixed with 60g of n-octadecyl alcohol and 0.8g of potassium hydroxide and distilled at -0.07~-0.06MPa and 126℃ onto a 60cm Widmanstätten column. 57.2g of 98.2% disiloxane was collected by distillation, with a yield of 71.3%.

[0030] The obtained disiloxane was tested, and the test results are as follows: Figure 1 As shown, its 1H NMR spectrum data are as follows: 1 H-NMR (400 MHz, CDCl3, δ): 0.03-0.08ppm (12H, Si CH3 ), 0.39-0.60ppm (4H, Si) CH2CH2 Si). The 1H NMR data indicates that the product obtained is 2,2,5,5-tetramethyl-2,5-disil-1-oxacyclopentane.

[0031] Example 2

[0032] This embodiment differs from Example 1 in that the first solvent in S1 is toluene, Pt is 15 ppm, the acetylene flow rate is 12 L / h, and acetylene is passed through for 2 hours; the ammonia concentration in S2 is 5%, and the molar ratio of ammonia to dimethylchlorosilane is 1.1:1; and the second solvent in S3 is dibutyl phthalate. Finally, the product yield from distillation is 69.3%.

[0033] Comparative Example 1 The difference between this comparative example and Example 1 is that S2 was directly hydrolyzed with 500% pure water (by weight of 1,2-bis(chlorodimethylsilyl)ethane) to obtain 183.4 g of a nearly colorless turbid liquid, and S3 was solvent-free, ultimately yielding 20.5 g of 2,2,5,5-tetramethyl-2,5-disil-1-oxacyclopentane, with a yield of 25.6%.

[0034] 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 2,5-disil-1-oxacyclopentane compounds, characterized in that, Includes the following steps: S1, under inert gas protection and stirring, dialkylchlorosilane, the first solvent and the first catalyst are mixed and acetylene is introduced to carry out a hydrosilylation reaction. After the reaction is completed, 1,2-bis(chlorodialkylsilyl)ethane is obtained by distillation to remove impurities. S2, under stirring, an alkaline solution is added to the 1,2-bis(chlorodialkylsilyl)ethane described in S1, and after hydrolysis, separation, neutralization and drying, a mixture of siloxane cyclic and linear is obtained; S3, the siloxane cyclic mixture obtained in S2 is mixed with the linear mixture, the second solvent and the second catalyst, and then subjected to reduced pressure heating distillation to obtain the 2,5-disil-1-oxacyclopentane derivative.

2. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The structural formula of the dialkylchlorosilane mentioned in S1 is: R1 and R2 are each independently selected from alkyl groups having 1 to 4 carbon atoms.

3. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The first solvent in S1 includes toluene, xylene, isooctane or dodecane, and the amount of the first solvent is 100 to 200% of the mass of the dialkylchlorosilane.

4. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The first catalyst in S1 is a 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum catalyst. This 1,3-divinyl-1,1,3,3-tetramethyldisiloxane-platinum catalyst is prepared by dissolving chloroplatinic acid hexahydrate in 1,3-divinyltetramethyldisiloxane and isopropanol under inert gas protection, heating at 70-80°C for 1.5-2.5 hours, followed by cooling and filtration. N,N-dimethylaniline is then added to the filtrate. The Pt content in the first catalyst is 3-30 ppm of the mass of the dialkylchlorosilane.

5. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The molar ratio of acetylene to dimethylchlorosilane in S1 is (0.5~1.2):

1.

6. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The dialkylchlorosilane, the first solvent, and the first catalyst in S1 are mixed and kept at 50-60°C for 0.5-1 h; the hydrosilylation reaction is carried out at 70-80°C for 2-3 h.

7. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The alkaline solution in S2 includes an ammonia solution with a mass concentration of 5-10%; the molar ratio of ammonia to dialkylchlorosilane in the alkaline solution is (1-1.3):1; the hydrolysis reaction is carried out at a temperature of 10-20°C for 0.5-2 hours.

8. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The second solvent in S3 includes n-octadecyl alcohol, n-hexadecyl alcohol, white oil, paraffin oil or dibutyl phthalate, and the amount of the second solvent is 30 to 80% of the mass of the dialkylchlorosilane.

9. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The second catalyst in S3 includes tetramethylammonium hydroxide, a complex of tetramethylammonium hydroxide with dimethyl silicone oil and tetramethylcyclotetrasiloxane, potassium hydroxide or lithium hydroxide; the amount of the second catalyst is 0.8 to 2% of the mass of the dialkylchlorosilane.

10. The method for preparing 2,5-disil-1-oxacyclopentane compounds according to claim 1, characterized in that, The pressure for depressurization heating described in S3 is -0.07 to -0.06 MPa, and the temperature is 120 to 130°C.

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