A method for jointly preparing mercaptosilane and guanidinosilane coupling agent

Abstract

The invention provides a method for jointly preparing mercaptosilane and guanidinosilane coupling agents, comprising the following steps: firstly reacting thiourea and chloropropylsilane to form an amidine salt intermediate, then dripping aminosilane to react and obtain mercaptosilane, after standing and separating, distilling the upper layer liquid to obtain mercaptosilane coupling agent and high boiling products, neutralizing the lower layer liquid and high boiling products with sodium alcoholate, separating and distilling to obtain guanidino-containing silane coupling agent. The method can simultaneously obtain two products, mercaptosilane and guanidinosilane, by adding aminosilane, and solves the problem of more guanidino salt byproducts and difficult treatment in the traditional thiourea production process.

Description

Technical Field

[0001] The invention relates to the field of fine chemicals, and in particular to a method for jointly preparing a mercaptosilane and a guanidinosilane coupling agent. Background Art

[0002] Mercaptosilane is a silane coupling agent containing a mercapto group in its molecular structure. The most common mercaptosilanes are 3-mercaptopropyltrimethoxysilane and 3-mercaptopropyltriethoxysilane. Mercaptosilane is often used for surface treatment of inorganic fillers such as silica and carbon black. It can act as an active agent, coupling agent, cross-linking agent, and reinforcing agent in polymers such as rubber and silicone. It can also be used as a fabric finishing agent, shrinkage-resistant agent, and raw material for hair care products.

[0003] At present, there are many industrial production methods for mercaptosilane. Generally speaking, there are two main types based on the source of mercapto in silane: one is to use thiourea as raw material, and the method is to react thiourea with chloropropyl alkoxysilane to form an amidine salt intermediate, and then react with ammonia or organic amine to obtain mercaptosilane; the other is to use sodium hydrosulfide as raw material, which is divided into anhydrous method and phase transfer method. The anhydrous method is to add hydrogen sulfide under pressure to an alcohol sodium solution to react to form an anhydrous alcohol solution of sodium hydrosulfide, and then add chloropropyl alkoxysilane to react to form mercaptosilane; the phase transfer method is to add solid sodium hydrosulfide containing crystal water as raw material to water with a buffer to form an aqueous solution of sodium hydrosulfide, and then add a phase transfer catalyst and drop chloropropyl alkoxysilane to react to form mercaptosilane.

[0004] The disadvantage of the anhydrous process of method 2 is that the initial raw material hydrogen sulfide used is a highly toxic gas and the reaction is under pressure, which has high safety risks and safety management costs; the phase transfer method is carried out in water, and silane is easily hydrolyzed in water, resulting in a low yield of high-boiling products in the product or even no product is obtained. Therefore, the current domestic method for producing mercaptosilane is still mainly based on the thiourea method.

[0005] The thiourea process for producing mercaptosilane also has disadvantages: the main by-product of the thiourea process is guanidine hydrochloride, and the amount of guanidine salt solid waste produced for every ton of mercaptosilane produced is about one ton. The by-product has a strong odor and a relatively large output, so the cost of treatment is relatively high. In this regard, finding an economical treatment method for guanidine salt, a by-product of mercaptosilane synthesis by the thiourea process, has become the focus of research by many scientific and technological workers. Summary of the invention

[0006] Based on this, the object of the present invention is to provide a method for jointly preparing mercaptosilane and guanidinosilane coupling agent, which can effectively solve the problem of guanidine salt as a by-product in the production of mercaptosilane from thiourea, and has a simple, safe and low-cost process.

[0007] The present invention achieves the above technical objectives through the following technical solutions:

[0008] The present invention provides a method for jointly preparing a mercaptosilane and a guanidinosilane coupling agent, comprising the following steps:

[0009] Add thiourea and 3-chloropropyl alkoxysilane into a reaction container in proportion, then add a reaction initiator, and stir the reaction at 130-150° C. until the material changes from solid-liquid two phases to a uniform transparent liquid;

[0010] After the reaction is completed, the temperature is lowered to 70-80°C, and an aminosilane coupling agent is added dropwise for reaction. After the addition is completed, the reaction is continued for 2-2.5 hours, and then the temperature is lowered to room temperature, and the layers are allowed to stand to separate, and an upper colorless liquid layer and a lower light yellow viscous liquid layer are obtained;

[0011] The upper colorless liquid layer is distilled under reduced pressure to obtain a mercaptosilane coupling agent product and a high-boiling residue;

[0012] After mixing the high-boiling residue and the lower layer material, sodium alcohol solution is added dropwise at room temperature, and reacted at 10-50°C to obtain a mixture. The mixture is filtered and the filtrate is distilled to obtain a guanidine-containing silane coupling agent.

[0013] Wherein, 3-chloropropyl alkoxysilane is:

[0014]

[0015] Here, R is any one of a methyl group and an ethyl alkyl group.

[0016] As a preferred embodiment, the molar ratio of thiourea to 3-chloropropylalkoxysilane is (1.05-1.1):1.

[0017] As a preferred embodiment, the reaction initiator includes but is not limited to potassium iodide.

[0018] As a preferred embodiment, the amount of the initiator used is 0.1-0.2% of the total mass of thiourea and 3-chloropropylalkoxysilane.

[0019] As a preferred embodiment, the aminosilane coupling agent is added dropwise under stirring at normal pressure, and the adding time is controlled within 1 to 2 hours.

[0020] As a preferred embodiment, the aminosilane coupling agent is selected from one or more of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane or N-(2-aminoethyl)-3-aminopropyltriethoxysilane; the molar ratio of aminosilane to 3-chloropropylalkoxysilane is (0.98-1.0): 1. The molar feed amount of the aminosilane coupling agent is not more than or slightly less than the amount of 3-chloropropylalkoxysilane, which is beneficial to increase the content of the guanidinosilane coupling agent in the distillation process.

[0021] As a preferred embodiment, the conditions for the reduced pressure distillation of the upper colorless liquid layer are: distillation temperature 90-135° C., vacuum degree above -0.098 MPa.

[0022] As a preferred embodiment, the conditions for distillation of the filtrate are: first distill out methanol at normal pressure and 100-115°C, then distill out the front fraction at a vacuum degree of -0.098MPa and within 125°C, and finally distill at a vacuum degree of more than -0.099MPa at 125-150°C to obtain a fraction, which is a guanidine-containing silane coupling agent.

[0023] As a preferred embodiment, the sodium alkoxide solution is a sodium methoxide or sodium ethoxide solution; the molar ratio of the amount of sodium alkoxide to 3-chloropropylalkoxysilane is (1.0-1.02): 1. The sodium methoxide and sodium ethoxide used are alcohol solutions, which are convenient for controlling the feeding amount and feeding.

[0024] The structure of the guanidine-containing silane coupling agent prepared by the above method is:

[0025]

[0026]

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) The present invention uses aminosilane as a reaction raw material, which can be used as a basic raw material for producing guanidinosilane, ensuring that the prepared products are mercaptosilane and guanidinosilane, solving the problem of more guanidine salt by-products and difficult treatment in the traditional thiourea production process; at the same time, the obtained guanidine-containing hydrochloride is a liquid substance, which is easy to liquid-liquid stratification with mercaptosilane, which is beneficial to improve the yield of the product and is easy to operate.

[0029] (2) The silicon-containing guanidine salt obtained by the reaction is a viscous liquid, which is easy to separate from the mercaptosilane; the crude product is separated by separation and then distilled. Compared with the traditional process of filtering and separating guanidine salt, it is simple to operate, has high separation efficiency, low loss and high yield, and the final by-product is sodium chloride salt with a small yield, simple to handle and low cost;

[0030] (3) The method has simple process and equipment, mild reaction conditions, and is easy to realize industrial production. The yield of mercaptosilane can reach 90-95%, the purity is above 98.5%, and the molar yield of guanidinosilane can reach 90-96%, the purity is above 97.5%. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0032] The following embodiments are only used to illustrate the present invention, but are not used to limit the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0033] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art. In the examples of the present invention, the raw materials used are conventional commercial products.

[0034] Example 1

[0035] 470.5g (6.18mol) of thiourea and 1193g (6.0mol) of 3-chloropropyltrimethoxysilane were added to a 2L flask equipped with mechanical stirring, condensation, reflux and oil bath heating, and 2.5g of potassium iodide was added as an initiator; mechanical stirring was turned on and heated to 140-150°C and stirred for 8-9h to form a homogeneous transparent liquid. After the reaction was completed, the temperature of the reactant was lowered to maintain at 70-75°C, and 1076g (6.0mol) of 3-aminopropyltrimethoxysilane was slowly added dropwise for 1.5h. After the addition was completed, the reaction continued for 2h to cool down.

[0036] The above reaction materials were introduced into a glass separating funnel and allowed to stand for 6 to 8 hours. The lower layer of viscous liquid and the upper layer of colorless transparent liquid were collected separately. The upper layer of materials was charged into a 2L glass distillation apparatus. 1107g of 3-mercaptopropyltrimethoxysilane product was distilled out at a vacuum degree of -0.098 to -0.099MPa and a kettle temperature of 100 to 120°C. The content of the product was 99.2% detected by GC.

[0037] The high-boiling products of distilled mercaptosilane are mixed with the viscous material in the lower layer, and transferred into a 2L flask with stirring and water bath cooling; 1095g of 30.2% sodium methoxide methanol solution is slowly added dropwise through a dropping funnel. The temperature will rise during the dropwise reaction. At this time, the cooling and the dropping speed are controlled to control the reaction at 10-50°C. After the sodium methoxide is added dropwise, the reaction is continued for 0.5h to terminate the reaction and obtain a low-viscosity solid-liquid mixture.

[0038] The obtained reaction mixture was transferred to a filtration device for filtration, and 405 g of solid filter residue was separated. The obtained light yellow filtrate was transferred to a distillation device, and the kettle temperature was first distilled at normal pressure to 100-105°C to distill out most of the methanol, and then the front fraction was distilled out within a vacuum degree of less than -0.09 MPa and a kettle temperature of less than 120°C; then the oil pump vacuum was used to control the distillation at a temperature above -0.099 MPa, and the fraction with a feed temperature of 126-135°C was taken out as the 2-(3-trimethoxysilylpropyl)guanidine silane product. The weight of the product was 1262 g, and the product content was detected to be 98.2%.

[0039] Example 2

[0040] 470.5g (6.18mol) of thiourea and 1445g (6.0mol) of 3-chloropropyltriethoxysilane were added to a 3L flask equipped with mechanical stirring, condensation, reflux and oil bath heating devices, and 3.5g of potassium iodide was added as an initiator; mechanical stirring was turned on and heated to 130-135°C and stirred for 9-10h to form a homogeneous transparent liquid. After the reaction was completed, the temperature of the reactant was lowered to maintain at 70-75°C, and 1302g (6.0mol) of 3-aminopropyltriethoxysilane was slowly added dropwise for 2.0h. After the addition was completed, the reaction continued for 2.5h and the temperature was lowered.

[0041] The above reaction materials were introduced into a glass separatory funnel and allowed to stand for 6 to 8 hours. The lower layer of viscous liquid and the upper layer of colorless transparent liquid were collected respectively. The upper layer of materials was charged into a 3L glass distillation apparatus. 1302g of 3-mercaptopropyltriethoxysilane product was distilled out at a vacuum degree of -0.099MPa and a kettle temperature of 110 to 130°C. The content of the product was 98.6% by GC.

[0042] The high-boiling products of distilled mercaptosilane are mixed with the viscous material in the lower layer, and transferred into a 3L flask with stirring and water bath cooling; 1965g of 21.2% sodium ethoxide ethanol solution is slowly added dropwise through a dropping funnel. The temperature will rise during the dropwise reaction. At this time, the cooling and the dropping speed are controlled to control the reaction at 10-50°C. After the sodium ethoxide is added dropwise, the reaction is continued for 0.5h to terminate the reaction and obtain a low-viscosity solid-liquid mixture.

[0043] The obtained reaction mixture was transferred to a filtration device for filtration, and 425 g of solid filter residue was separated. The obtained light yellow filtrate was transferred to a distillation device, and the majority of the ethanol was distilled out by atmospheric distillation at a kettle temperature of 100-115°C. Then, the front fraction with a vacuum degree within -0.095 MPa and a kettle temperature within 125°C was distilled out under low vacuum. Then, the oil pump vacuum was used to control the distillation at a temperature above -0.099 MPa. The fraction with a feed temperature within 132-142°C was taken out as the 2-(3-triethoxysilylpropyl)guanidine silane product. The weight of the product was 1490 g, and the product content was detected to be 97.6%.

[0044] Example 3

[0045] 470.5g (6.18mol) of thiourea and 1096g (6.0mol) of 3-chloropropylmethyldimethoxysilane were added to a 3L flask equipped with mechanical stirring, condensation, reflux and oil bath heating, and 3.0g of potassium iodide was added as an initiator; mechanical stirring was turned on and heated to 135-140°C and stirred for 5-6h to form a homogeneous transparent liquid. After the reaction was completed, the temperature of the reactant was lowered to maintain at 75-80°C, and 1334g (6.0mol) of N-(2-aminoethyl)-3-aminopropyltrimethoxysilane was slowly added dropwise for 1.5h. After the addition was completed, the reaction was continued for 2.0h and the temperature was lowered.

[0046] The above reaction materials were introduced into a glass separatory funnel and allowed to stand for 6 to 8 hours. The lower layer of viscous liquid and the upper layer of colorless transparent liquid were collected separately. The upper layer of materials was charged into a 3L glass distillation apparatus. 1025g of 3-mercaptopropylmethyldimethoxysilane product was distilled out at a vacuum degree of -0.098 to -0.099MPa and a kettle temperature of 100 to 115°C. The content of the product was 98.9% detected by GC.

[0047] The high-boiling products of distilled mercaptosilane are mixed with the viscous material in the lower layer, and transferred into a 3L flask with stirring and water bath cooling; 1074g of 30.2% sodium methoxide methanol solution is slowly added dropwise through a dropping funnel. The temperature will rise during the dropwise reaction. At this time, the temperature is controlled to be controlled at 10-50°C. After the sodium methoxide is added dropwise, the reaction is continued for 1h to terminate the reaction and a low-viscosity solid-liquid mixture is obtained.

[0048] The obtained reaction mixture was transferred to a filtration device for filtration, and 412 g of solid filter residue was separated. The obtained yellow filtrate was transferred to a distillation device, and firstly the kettle temperature was raised to 100-105°C to distill out most of the methanol, and then the front fraction was distilled out at a vacuum degree of less than -0.09 MPa and a kettle temperature of less than 120°C; then the oil pump was used to control the distillation at a vacuum degree of more than -0.099 MPa, and the fraction with a feed temperature of 140-150°C was taken out as the 2-(3-trimethoxysilylpropyl)-N-(2-aminoethyl)guanidine silane product. The weight of the product was 1393 g, and the product content was detected to be 97.8%.

[0049] It is necessary to point out that the above embodiments are limited to further elaboration and explanation of the technical solution of the present invention, and are not further limitations of the technical solution of the present invention. The method of the present invention is only a preferred implementation scheme, and is not used to limit the protection scope of the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for jointly preparing mercaptosilane and guanidinosilane coupling agents, characterized in that: The following steps are involved: Add thiourea and 3-chloropropyl alkoxysilane into the reaction container in proportion, then add the reaction initiator, and stir the reaction at 130-150°C until the material changes from solid-liquid two phases to a uniform transparent liquid; After the reaction is completed, the temperature is lowered to 70-80°C, and an aminosilane coupling agent is added dropwise for reaction. After the addition is completed, the reaction is continued for 2-2.5 hours, and then the temperature is lowered to room temperature, and the layers are allowed to stand to separate, and an upper colorless liquid layer and a lower light yellow viscous liquid layer are obtained; The upper colorless liquid layer is distilled under reduced pressure to obtain a mercaptosilane coupling agent product and a high-boiling residue; After mixing the high-boiling residue and the lower layer material, sodium alcoholate solution is added dropwise at room temperature, and the mixture is reacted at 10-50°C to obtain a mixture, and the mixture is filtered and the filtrate is distilled to obtain a guanidine-containing silane coupling agent; Wherein, the 3-chloropropyl alkoxysilane is selected from 3-chloropropyl trimethoxysilane, 3-chloropropyl triethoxysilane or 3-chloropropyl methyl dimethoxysilane; the aminosilane coupling agent is selected from 3-aminopropyl trimethoxysilane, 3-aminopropyl triethoxysilane or N-(2-aminoethyl)-3-aminopropyl trimethoxysilane.

2. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The molar ratio of thiourea to 3-chloropropylalkoxysilane is (1.05~1.1):

1.

3. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The reaction initiator is selected from potassium iodide.

4. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The amount of the initiator used is 0.1-0.2% of the total mass of thiourea and 3-chloropropylalkoxysilane.

5. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The aminosilane coupling agent is added dropwise under stirring at normal pressure, and the addition time is controlled within 1 to 2 hours.

6. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The molar ratio of aminosilane to 3-chloropropylalkoxysilane is (0.98~1.0):

1.

7. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The conditions for the reduced pressure distillation of the upper colorless liquid layer are: distillation temperature 90~135℃, vacuum degree above -0.098MPa.

8. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The conditions for distillation of the filtrate are: firstly distill out the alcohol at normal pressure and 100-115°C, then distill out the front fraction at a vacuum degree of less than -0.098MPa and 125°C, and finally distill out the fraction at a vacuum degree of more than -0.099MPa and 125-150°C, which is the silane coupling agent containing a guanidine group.

9. The method for jointly preparing mercaptosilane and guanidinosilane coupling agent according to claim 1, characterized in that: The sodium alcoholate solution is sodium methoxide solution or sodium ethoxide solution; or, The molar ratio of sodium alcoholate to 3-chloropropylalkoxysilane is (1.0~1.02):1.

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