Mercaptopropyl trimethoxy silane synthesis method

Abstract

The invention provides a synthesis method of mercaptopropyltrimethoxysilane, which comprises the following steps: dissolving industrial sodium hydrosulfide in a composite solvent, separating water through azeotropic distillation, reacting the separated and dewatered industrial sodium hydrosulfide-composite solvent solution with chloropropyltrimethoxysilane to obtain a reaction product, and carrying out heat preservation on the reaction product; carrying out cooling, filter pressing, rectification and separation on the reaction product subjected to heat preservation to obtain mercaptopropyltrimethoxysilane; the composite solvent comprises a first type of solvent and a second type of solvent, the first type of solvent is a non-water-soluble solvent, and the second type of solvent is a water-soluble solvent. According to the method, after water in sodium hydrosulfide is removed through azeotropic distillation, chloropropyltrimethoxysilane is added for full reaction, so that reaction products are prevented from being reacted with water, and after the reaction is completed, high-purity mercaptopropyltrimethoxysilane is obtained through cooling, filter pressing and distillation separation.

Description

Technical Field

[0001] This application relates to the field of organic chemical synthesis technology, and more specifically, to a method for synthesizing mercaptopropyltrimethoxysilane. Background Technology

[0002] Mercaptopropyltrimethoxysilane is an important organosilicon compound widely used as a coupling agent, crosslinking agent, and surfactant. Its synthesis methods are diverse, but traditional methods suffer from problems such as harsh reaction conditions, numerous byproducts, and low yields. For example:

[0003] Patent application publication (CN102659831A) discloses a method for synthesizing γ-mercaptopropyltrimethoxysilane. This method involves dissolving NaHS in water and adjusting the pH to below 7.0; then mixing γ-chloropropyltrimethoxysilane, ethanol, a phase transfer catalyst, and a stabilizer; next, evacuating the synthesis reactor and introducing a mixture of N2 and CO2 gases, adjusting the reactor temperature to 65–70°C; then adding the NaHS solution with a pH less than 7.0 and the mixture of γ-chloropropyltrimethoxysilane, ethanol, and the phase transfer catalyst separately into the synthesis reactor for the synthesis reaction; finally, separating the reactants into layers, and distilling the upper oil phase to obtain the product γ-mercaptopropyltrimethoxysilane. The synthesis method disclosed in this document requires the introduction of phase transfer catalysts such as dodecyltrimethylammonium chloride and tetrabutylammonium bromide, necessitating a catalyst removal step, resulting in a complex process and high cost.

[0004] Patent application publication (CN105153216A) discloses a method for preparing 3-mercaptopropyltrimethoxysilane. This method involves dissolving hydrated sodium sulfide in methanol, adding silicon tetrachloride to react, and then adding tetramethoxysilane to completely consume excess water after the reaction. Chloropropyltrimethoxysilane is then added to a four-stage reaction vessel to obtain crude 3-mercaptopropyltrimethoxysilane. The crude product is then purified by vacuum distillation to obtain a high-purity 3-mercaptopropyltrimethoxysilane final product. However, this method suffers from stringent reaction conditions.

[0005] The inventors of this application have discovered that if the above method uses only hydrated sodium hydrosulfide and chloropropyltrimethoxysilane as raw materials, the target product mercaptopropyltrimethoxysilane will react and hydrolyze upon contact with water to generate mercaptopropanol and trimethylsilanol. Summary of the Invention

[0006] The technical problem to be solved by this application is to provide a method for synthesizing mercaptopropyltrimethoxysilane, which solves the problem that mercaptopropyltrimethoxysilane cannot be directly prepared by reacting industrial sodium hydrosulfide with chloropropyltrimethoxysilane.

[0007] To address the aforementioned problems, this application provides a method for synthesizing mercaptopropyltrimethoxysilane, comprising:

[0008] Industrial sodium hydrosulfide was dissolved in a composite solvent, and water was separated by azeotropic distillation. The separated and dehydrated industrial sodium hydrosulfide-composite solvent solution was then reacted with chloropropyltrimethoxysilane to obtain a reaction product, which was then kept at a certain temperature.

[0009] The reaction product after heat preservation was cooled, filtered, distilled and separated to obtain mercaptopropyltrimethoxysilane;

[0010] The composite solvent includes a first type of solvent and a second type of solvent, wherein the first type of solvent is a non-water-soluble solvent and the second type of solvent is a water-soluble solvent;

[0011] The mass ratio of the first solvent to the second solvent is 1:2.6 to 8.

[0012] The aforementioned industrial sodium hydrosulfide refers to sodium hydrosulfide hydrate.

[0013] As one option for the mass ratio of industrial sodium hydrosulfide to the composite solvent, the mass ratio of industrial sodium hydrosulfide to the composite solvent is 1:2 to 3.5.

[0014] As a preferred option among the above technical solutions, the mass ratio of the sodium hydrosulfide participating in the reaction to the chloropropyltrimethoxysilane is 1:1.05-3.

[0015] As a preferred choice of solvent in the above technical solution, the first type of solvent includes solvents that readily form azeotropes with water. For example, the first type of solvent includes at least one of solvents that readily form azeotropes with water, such as benzene, toluene, and isooctane.

[0016] The second type of solvent includes at least one of water-soluble solvents such as ethylene glycol, diethylene glycol dimethyl ether, dimethylformamide, and dimethyl sulfoxide.

[0017] As a preferred option for the above technical solution, the azeotropic distillation temperature is 60–130°C and the pressure is atmospheric pressure.

[0018] As a preferred option of the above technical solution, the temperature for keeping the reaction product warm is 65-120℃, and the holding time is 2h.

[0019] The beneficial effects of this application are as follows:

[0020] To address the issue that the target product mercaptopropyltrimethoxysilane reacts with water to hydrolyze and generate mercaptopropanol and trimethylsilanol, thus preventing the acquisition of the template product, this application employs azeotropic distillation to remove water from sodium hydrosulfide, followed by the addition of chloropropyltrimethoxysilane for complete reaction. This avoids the reaction product reacting with water. Furthermore, the reaction product is cooled, filtered, distilled, and separated after being kept at a constant temperature to obtain high-purity mercaptopropyltrimethoxysilane.

[0021] The composite solvent of this application is a mixture of water-soluble organic solvent and non-water-soluble organic solvent, thereby improving the binding ability of the composite solvent with the complexed water in sodium hydrosulfide, thereby removing the water from the sodium hydrosulfide and forming an azeotrope after mixing with the composite solvent, thus realizing the removal of water from the industrial sodium hydrosulfide reactant by distillation. Detailed Implementation

[0022] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0023] This application provides a method for synthesizing mercaptopropyltrimethoxysilane, comprising:

[0024] S1. Industrial sodium hydrosulfide is dissolved in a composite solvent, and water is separated by azeotropic distillation. The separated and dehydrated industrial sodium hydrosulfide-composite solvent solution is reacted with chloropropyltrimethoxysilane to obtain a reaction product, and the reaction product is kept at 65-75°C for 2 hours. In this step, the mass ratio of industrial sodium hydrosulfide to the composite solvent is 1:2-3.5, the azeotropic distillation temperature is 60-130°C, and the pressure is atmospheric pressure. In this step, the composite solvent includes a first type of solvent and a second type of solvent. The first type of solvent is a non-water-soluble solvent, and the second type of solvent is a water-soluble solvent. The first type of solvent includes at least one of solvents that readily form azeotropes with water, such as benzene, toluene, and isooctane. The second type of solvent includes at least one of water-soluble solvents, such as ethylene glycol, diethylene glycol dimethyl ether, dimethylformamide, and dimethyl sulfoxide.

[0025] S2. The reaction product after heat preservation is cooled, filtered, distilled and separated to obtain mercaptopropyltrimethoxysilane.

[0026] Based on the embodiments provided in this application, some specific experiments have been conducted on this application. On this basis, some comparative examples are also given. From these embodiments and comparative examples, it can be seen that the solution provided in this application has achieved good results. It should be noted that the following embodiments are only used to illustrate this application in detail and do not limit the scope of protection of the invention in any way.

[0027] Example 1

[0028] S1. Dissolve 800g of industrial sodium hydrosulfide with a water content of 30% in 2160g of a composite solvent (the first solvent in the composite solvent is 60g of benzene, and the second solvent is 1800g of ethylene glycol). After azeotropic distillation at 69℃ and atmospheric pressure for 2 hours, 232.9g of water and 0.413g of the composite solvent are obtained. In this step, the mass ratio of benzene to ethylene glycol is 1:5, and the mass ratio of industrial sodium hydrosulfide to the composite solvent is 1:2.25.

[0029] The industrial sodium hydrosulfide-composite solvent solution after separation and removal of water and residual composite solvent was reacted with 2000g of chloropropyltrimethoxysilane to obtain the reaction product, and the reaction product was kept at 70℃ for 2 hours.

[0030] S2. The reaction product after heat preservation was cooled to 35°C, filtered under pressure, and then separated by distillation at 83±1°C to obtain 1393.79g of mercaptopropyltrimethoxysilane with a purity of 98.6%.

[0031] Examples 2-10

[0032] Examples 2-10 synthesized mercaptopropyltrimethoxysilane using the same method as in Example 1, except that the type of the second solvent used was different, the mass ratio of the first solvent to the second solvent was different, the mass ratio of industrial sodium hydrosulfide to the composite solvent was different, and the azeotropic distillation temperature was different. Step S1 is detailed in Table 1, and step S2 is detailed in Table 2. The results of the detection of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Examples 1-10 are shown in Table 2.

[0033] Table 1 Control conditions for steps S1 in Examples 1-10

[0034]

[0035]

[0036] Table 2. Control conditions for step S2 in Examples 1-10 and the synthesis products of mercaptopropyltrimethoxysilane.

[0037]

[0038] Comparative Examples 1-6

[0039] Comparative Example 1

[0040] The difference between this comparative example and Example 2 is that in the azeotropic distillation process of Comparative Example 1, only the first solvent benzene is used in step S1, without the second solvent. The rest is the same as in Example 2. The control conditions of step S1 are detailed in Table 3, and the control conditions of step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Comparative Example 1 are shown in Table 4.

[0041] Comparative Example 2

[0042] The difference between this comparative example and Example 2 is that in the azeotropic distillation process of Comparative Example 2, only dimethylformamide as the second solvent was used, and no first solvent benzene was added. Otherwise, it was the same as Example 2. The control conditions of step S1 are detailed in Table 3, and the control conditions of step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Comparative Example 2 are shown in Table 4.

[0043] Comparative Example 3

[0044] The difference between this comparative example and Example 2 is that the composite solvent used in the azeotropic distillation process of Comparative Example 3 in step S1 is a mixture of toluene and benzene. The other conditions are the same as in Example 2. The control conditions of step S1 are detailed in Table 3, and the control conditions of step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Comparative Example 3 are shown in Table 4.

[0045] Comparative Example 4

[0046] The difference between this comparative example and Example 2 is that the composite solvent used in the azeotropic distillation process of Comparative Example 4 in step S1 is a mixture of ethylene glycol and dimethylformamide. The rest is the same as in Example 2. The control conditions of step S1 are detailed in Table 3, and the control conditions of step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Comparative Example 4 are shown in Table 4.

[0047] Comparative Example 5

[0048] The difference between this comparative example and Example 2 is that the benzene content in the composite solvent used in the azeotropic distillation process of Comparative Example 5 in step S1 is higher. Otherwise, it is the same as Example 2. The control conditions of step S1 are detailed in Table 3, and the control conditions of step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in Comparative Example 5 are shown in Table 4.

[0049] Comparative Example 6

[0050] The difference between this comparative example and Example 2 is that there is no azeotropic distillation process in step S1 of comparative example 6. Everything else is the same as in Example 2. The control conditions for step S1 are detailed in Table 3, and the control conditions for step S2 are detailed in Table 4. The detection results of the synthesis efficiency of mercaptopropyltrimethoxysilane obtained in comparative example 5 are shown in Table 4.

[0051] Table 3 Control conditions for steps S1 in Comparative Examples 1-6

[0052]

[0053]

[0054] Table 4. Control conditions for step S2 and synthesis products of mercaptopropyltrimethoxysilane in Comparative Examples 1–6

[0055]

[0056] As can be seen from Examples 1 to 10, the yield of mercaptopropyltrimethoxysilane obtained in Examples 1 to 10 is higher than 1393, and the purity of the product reaches more than 98%. Among them, the mercaptopropyltrimethoxysilane obtained in Example 3 has the highest yield.

[0057] Comparative Examples 1 to 4 and Comparative Example 6 could not yield mercaptopropyltrimethoxysilane because water was present in the raw materials. Mercaptopropyltrimethoxysilane reacts and hydrolyzes when it comes into contact with water, making it impossible to effectively obtain mercaptopropyltrimethoxysilane.

[0058] As can be seen from Example 2 and Comparative Example 5, the yield of mercaptopropyltrimethoxysilane obtained in Comparative Example 5 was reduced because the benzene content in the azeotropic distillation solvent was low, resulting in a low product yield.

[0059] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for synthesizing mercaptopropyltrimethoxysilane, characterized in that, include: Industrial sodium hydrosulfide was dissolved in a composite solvent, and water was separated by azeotropic distillation. The separated and dehydrated industrial sodium hydrosulfide-composite solvent solution was then reacted with chloropropyltrimethoxysilane to obtain a reaction product, which was then kept at a certain temperature. The reaction product after heat preservation was cooled, filtered, distilled and separated to obtain mercaptopropyltrimethoxysilane; The composite solvent includes a first type of solvent and a second type of solvent, wherein the first type of solvent is a non-water-soluble solvent and the second type of solvent is a water-soluble solvent; The mass ratio of the first solvent to the second solvent is 1:2.6 to 8.

2. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The industrial sodium hydrosulfide mentioned is sodium hydrosulfide hydrate.

3. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The mass ratio of the industrial sodium hydrosulfide to the composite solvent is 1:2 to 3.

5.

4. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The mass ratio of the industrial sodium hydrosulfide to the chloropropyltrimethoxysilane is 1:1.05-3.

5. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The first type of solvent includes solvents that readily form azeotropes with water.

6. The method for synthesizing mercaptopropyltrimethoxysilane according to any one of claims 1 or 5, characterized in that, The first type of solvent includes at least one of benzene, toluene, and isooctane.

7. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The second type of solvent includes at least one of ethylene glycol, diethylene glycol dimethyl ether, dimethylformamide, and dimethyl sulfoxide.

8. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The azeotropic distillation temperature is 60–130°C and the pressure is atmospheric pressure.

9. The method for synthesizing mercaptopropyltrimethoxysilane according to claim 1, characterized in that, The temperature at which the reaction product is kept warm is 65–120°C.

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