Hydrogen-containing siloxane and method for producing the same

Abstract

The application provides a hydrogen-containing siloxane and a preparation method thereof. The method comprises the following steps: reacting ammonia gas in a solution of hydrogen-containing chlorosilane, and filtering to obtain a mother liquor; reacting the mother liquor of S1 with alcohol, and performing rectification to obtain the hydrogen-containing siloxane. The application can convert the hydrogen-containing chlorosilane into the hydrogen-containing siloxane with high selectivity, avoid the generation of HCl in the traditional method, inhibit side reactions, and improve the yield of the target product.

Description

Technical Field

[0001] This invention belongs to the field of organosilicon, specifically relating to a hydrogen-containing siloxane and its preparation method. Background Technology

[0002] Hydrogen-containing siloxanes possess both hydrolyzable alkoxy groups and active silane-hydrogen bonds. They can undergo hydrosilylation reactions with a series of alkene monomers in the presence of a platinum catalyst through silane-hydrogen bonds, introducing different functional groups to obtain various silane coupling agents and base adhesives for organosilicon-modified polyether sealants. They are an important organosilicon intermediate. At the same time, these silanes are also important raw materials for the preparation of hydrogen-containing silicone oils, addition-type silicone rubbers, and silicone resins, and can improve the physical and chemical properties of many copolymers.

[0003] Traditional industrial production of hydrosiloxanes involves the alcoholysis reaction of hydrochlorosilanes with alcohols. However, this reaction generates HCl (US4851558). HCl not only reacts with the reactant hydrochlorosilane and the product hydrosiloxane, but also catalyzes the condensation of alcohols to form ethers and water, leading to the hydrolysis and condensation of silanes and triggering a series of side reactions.

[0004] One way to avoid HCl formation is to add organic bases such as pyridine or phenyl dimethylamine to the reaction system to neutralize the HCl formed during the reaction. However, the resulting organic ammonium salts have a certain degree of solubility in the reaction solution, making them difficult to separate and purify (J.Am.Soc.Chem.1953,75,2712.). Another approach is to use reagents such as sodium alkoxide (US5189194) or diekoxy sulfoxide (Inorg.Chem.1963,2,825.) to replace alcohols as alkoxy donors for the reaction with hydrochlorosilanes. However, these reagents are chemically reactive and difficult to use for large-scale industrial production.

[0005] Therefore, there is an urgent need in this field for a highly selective method for synthesizing hydrogen-containing siloxanes. Summary of the Invention

[0006] The purpose of this invention is to provide a method for preparing hydrogen-containing siloxanes from hydrogen-containing chlorosilanes, which can obtain highly selective hydrogen-containing siloxanes.

[0007] To achieve the above-mentioned objective, this invention provides a two-step method for preparing hydrogen-containing siloxanes by first reacting a hydrogen-containing chlorosilane with ammonia and then with an alcohol, as detailed below:

[0008] A method for preparing a hydrogen-containing siloxane, the method comprising the following steps:

[0009] S1: Ammonia gas is passed into a solution containing hydrochlorosilane to react, and the mother liquor is obtained by filtration;

[0010] S2: The mother liquor of S1 is reacted with alcohol, and after distillation, hydrogen-containing siloxane is obtained.

[0011] Unlike existing technologies, this application employs a two-step reaction method. First, ammonia is reacted with the raw material, a hydrochlorosilane, to replace chlorine atoms with ammonia. Excess ammonia neutralizes the generated hydrogen chloride. Subsequently, the reaction solution reacts with an alcohol at high temperature. The generated methyldimethoxysilane is vaporized and continuously carried out of the reaction system by nitrogen gas, and finally collected in a condenser.

[0012] In one embodiment, methyldichlorosilane and methanol are used for preparation, and the two-step reaction is illustrated below:

[0013] 3eq.MeHSiCl2+9eq.NH3→(MeHSiNH)3+6eq·NH4Cl

[0014] (MeHSiNH)3+6eq·MeOH→3eq.MeHSi(OMe)2+3eq.NH3

[0015] In this invention, the hydrochlorosilane in S1 is methyldichlorosilane.

[0016] In this invention, ammonia is in excess in S1, and preferably the molar ratio of hydrochlorosilane to ammonia is 1:(3-6), more preferably 1:(4-6).

[0017] In this invention, the ammonia space velocity in S1 is 1-2 L / min, preferably 1.5-2 L / min.

[0018] In this invention, the reaction temperature in S1 is 0–20°C.

[0019] In this invention, the solvent of the S1 solution is one or more of aliphatic hydrocarbons or benzene-based organic solvents, preferably one or more of n-hexane, toluene, and xylene.

[0020] In this invention, the alcohol in S2 is ROH, and R is a C1-C8 alkyl group, preferably one or more of methanol, ethanol, and isopropanol, more preferably methanol.

[0021] In this invention, the molar ratio of intermediate product to alcohol in the mother liquor of S2 is 1:(6-9), preferably 1:(6-8).

[0022] In this invention, the reaction temperature in S2 is 55–100°C.

[0023] In this invention, the S2 distillation process is atmospheric pressure distillation.

[0024] As is well known in the art, in order to obtain better process results, the ammonia, solvent, alcohol, etc., need to be conventionally dehydrated before the above reaction.

[0025] Another object of the present invention is to provide a hydrogen-containing siloxane.

[0026] A hydrogen-containing siloxane prepared by the above method, wherein the chloride ion content in the hydrogen-containing siloxane is less than 50 ppm.

[0027] Compared with the prior art, the advantages of this invention are as follows:

[0028] (1) It avoids the generation of HCl, suppresses side reactions, and improves the selectivity of the target product.

[0029] (2) The process is easy to implement and facilitates industrial application. Detailed Implementation

[0030] The following examples further illustrate the synthesis method of the hydrogen-containing siloxanes of the present invention. These examples are implemented based on the technical solution of the present invention, providing detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following examples.

[0031] raw material:

[0032] Methyldichlorosilane, INNOCHEM, 98%;

[0033] Methanol and ethanol, INNOCHEM, 99.5% analytical grade;

[0034] Toluene, INNOCHEM, analytical grade;

[0035] Ammonia, Wanhua Chemical, 98%.

[0036] Gas chromatography instrument: Agilent 8890. Test method: Initial temperature 40℃, hold for 6 minutes; increase temperature by 5℃ / min to 80℃, hold for 0 minutes; increase temperature by 30℃ / min to 300℃, hold for 0 minutes.

[0037] Example 1

[0038] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 678 L of ammonia gas (molar ratio 1:6) was passed into the methyldichlorosilane solution at a rate of 2 L / min, maintaining the temperature in the reaction vessel at 20 °C. The reaction mother liquor was obtained after filtration. The reaction mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 60 °C. Under a nitrogen atmosphere, 323 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldimethoxysilane, was collected through a reflux condenser. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 93%, and the chloride ion content was 38 ppm.

[0039] Example 2

[0040] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 565 L of ammonia gas (molar ratio 1:5) was passed into the methyldichlorosilane solution at a rate of 1.2 L / min, maintaining the temperature in the reaction vessel at 15 °C. The reaction mother liquor was obtained after filtration. The reaction mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 95 °C. Under a nitrogen atmosphere, 323 g of ethanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the ethanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldiethoxysilane, was collected through a reflux condenser. Gas chromatography analysis of the liquid in the condenser showed a yield of 84% for methyldiethoxysilane and a chloride ion content of 43 ppm.

[0041] Example 3

[0042] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 339 L of ammonia gas (molar ratio 1:3) was passed into the methyldichlorosilane solution at a rate of 2 L / min, maintaining the temperature in the reaction vessel at 5 °C. The reaction mother liquor was obtained after filtration. The reaction mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 65 °C. Under a nitrogen atmosphere, 440 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldimethoxysilane, was collected through a reflux condenser. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 75%, and the chloride ion content was 49 ppm.

[0043] Example 4

[0044] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 678 L of ammonia gas (molar ratio 1:6) was passed into the methyldichlorosilane solution at a rate of 1.5 L / min, maintaining the temperature in the reaction vessel at 20 °C. The reaction mother liquor was obtained after filtration. The reaction mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 55 °C. Under a nitrogen atmosphere, 323 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldimethoxysilane, was collected through a reflux condenser at the rear. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 91%, and the chloride ion content was 41 ppm.

[0045] Example 5

[0046] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 678 L of ammonia gas (molar ratio 1:6) was passed into the methyldichlorosilane solution at a rate of 2 L / min, maintaining the temperature in the reaction vessel at 20 °C. The reaction mother liquor was obtained after filtration. The reaction mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 60 °C. Under a nitrogen atmosphere, 372 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldimethoxysilane, was collected through a reflux condenser at the rear. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 92%, and the chloride ion content was 40 ppm.

[0047] Example 6

[0048] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and cooled to 0 °C. 678 L of ammonia gas (molar ratio 1:6) was passed into the methyldichlorosilane solution at a rate of 2 L / min, maintaining the temperature in the reaction vessel at 20 °C. The mother liquor was obtained after filtration. The mother liquor was added to the reaction vessel, and the mixture was stirred and heated to 60 °C. Under a nitrogen atmosphere, 484 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours, and the target product, methyldimethoxysilane, was collected through a reflux condenser. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 88%, and the chloride ion content was 38 ppm.

[0049] Comparative Example 1

[0050] This comparative example is compared with Example 1.

[0051] 580 g of methyldichlorosilane and 580 g of toluene solvent were added to a reaction vessel, and the mixture was stirred and heated to 60 °C. Under a nitrogen atmosphere, 323 g of methanol was added dropwise to the reaction vessel at a rate of 2 g / min. After the methanol addition was complete, the mixture was stirred for 3 hours. The target product, methyldimethoxysilane, was collected through a reflux condenser at the rear end. The liquid in the condenser was analyzed by gas chromatography. The yield of methyldimethoxysilane was 29%, and the chloride ion content was 141 ppm.

[0052] In summary, this invention produces methyldimethoxysilane in high yield by reacting methyldichlorosilane with ammonia first, and then with methanol, avoiding the generation of hydrogen chloride, and has the potential for industrial production.

Claims

1. A method for preparing a hydrogen-containing siloxane, characterized in that, The method includes the following steps: S1: Ammonia gas is passed into a solution containing hydrochlorosilane to react, and the mother liquor is obtained by filtration; S2: The mother liquor of S1 is reacted with alcohol, and after distillation, hydrogen-containing siloxane is obtained.

2. The method according to claim 1, characterized in that, The hydrochlorosilane contained in S1 is methyldichlorosilane; And / or, there is an excess of ammonia in S1; And / or, the ammonia flow rate in S1 is 1-2 L / min; And / or, the reaction temperature in S1 is 0–20°C; And / or, the solvent of the S1 solution is one or more of aliphatic hydrocarbons or benzene-based organic solvents.

3. The method according to claim 2, characterized in that, The molar ratio of hydrochlorosilane to ammonia in S1 is 1:(3-6); And / or, the ammonia flow rate in S1 is 1.5-2 L / min; And / or, the solvent of the S1 solution is one or more of n-hexane, toluene, and xylene.

4. The method according to claim 2, characterized in that, The molar ratio of hydrochlorosilane to ammonia in S1 is 1:(4-6).

5. The method according to claim 1, characterized in that, In S2, the alcohol is ROH and R is a C1-C8 alkyl group; And / or, the molar ratio of intermediate product to alcohol in the mother liquor of S2 is 1:(6-9); And / or, the reaction temperature in S2 is 55–100°C; And / or, the S2 distillation process is atmospheric distillation.

6. The method according to claim 5, characterized in that, The alcohol in S2 is one or more of methanol, ethanol, and isopropanol; And / or, the molar ratio of intermediate product to alcohol in the mother liquor of S2 is 1:(6-8).

7. The method according to claim 6, characterized in that, The alcohol in S2 is methanol.