Preparation method of bis-[3-(triethoxysilyl) propyl]-disulfide

Abstract

The invention provides a preparation method of bis-[3-(triethoxysilyl) propyl]-disulfide. The preparation method comprises the following steps: S1, under the protection of nitrogen, dropwise adding chloropropene and trichlorosilane into a non-polar solvent, a first catalyst and tripropylamine, reacting at room temperature, taking filtrate, dropwise adding the filtrate into alcohol in a micro-reflux state, reacting, adding a sodium alkoxide / alcohol solution for neutralizing, filtering, and distilling to obtain allyltriethoxysilane; and S2, under ultraviolet light, mixing allyltriethoxysilane, mercaptopropyltriethoxysilane and benzoin dimethyl ether, reacting at room temperature for 2-3 hours, adding sulfur and a second catalyst, carrying out heating reaction, removing low boiling points, cooling, and filtering. According to the preparation method provided by the invention, bis-[3-(triethoxysilyl) propyl]-disulfide is successfully and effectively synthesized, a phase transfer catalyst does not need to be introduced for catalysis, hydrolysis of silane and treatment of saline water are reduced, the yield of single-kettle synthesis is high, and the utilization rate of equipment is high.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of synthesis of sulfur-containing silane, and more particularly to a preparation method of bis-[3-(triethoxysilyl)propyl]-disulfide. BACKGROUND

[0002] Sulfur-containing silane is a common processing aid in the rubber industry. At present, the sulfur-containing silane commonly researched and applied in the rubber tire industry is bis-[3-(triethoxysilyl)propyl]-disulfide (referred to as silicon 75) and bis-[3-(triethoxysilyl)propyl]-tetrasulfide (referred to as silicon 69). This kind of polysulfide silane has multiple effects of dispersant, vulcanizing agent and wetting agent, and can provide sulfur for the rubber system, which is not comparable to other coupling agents. The longer and more flexible vulcanization cross-linking bond can improve the dynamic mechanical properties of tire rubber. In industry, this kind of sulfur-containing silane is mostly synthesized by aqueous phase method. However, a large amount of sodium chloride and salt water with high COD content are generated as by-products in the preparation process of this kind of method (the output of wastewater is basically more than 1 / 2 of the product, and the single-pot efficiency is low). The treatment cost of such salt water is high, and the synthesis by aqueous phase method inevitably causes the hydrolysis of silane, resulting in low yield of target product and large fluctuation of product quality. At the same time, the aqueous phase method usually prepares a polysulfide sodium aqueous solution first, and then reacts with chloropropyl triethoxysilane under the catalysis of tetrabutylammonium bromide. In this method, the residual chloropropyl triethoxysilane, the by-product mercaptopropyl triethoxysilane, the decomposition of tetrabutylammonium bromide to produce tributylamine, and the hydrolysis of silane to produce alcohol are inevitable, resulting in high content of gas phase impurities. SUMMARY

[0003] The first object of the present application is to provide a preparation method of bis-[3-(triethoxysilyl)propyl]-disulfide, which can successfully and effectively synthesize bis-[3-(triethoxysilyl)propyl]-disulfide without introducing phase transfer catalysts, thereby reducing the hydrolysis of silane and the treatment of salt water.

[0004] The preparation method of bis-[3-(triethoxysilyl)propyl]-disulfide comprises the following steps: S1, under nitrogen protection, a mixed solution of chloropropylene and trichlorosilane is added dropwise into a non-polar solvent, a first catalyst and tripropylamine, after the dropwise addition is completed, the reaction is carried out at room temperature until the content of chloropropylene in the clear solution is not more than 0.5% by gas phase test, the filtrate is obtained by filtration, the filtrate is added dropwise into alcohol in a micro-reflux state for reaction, after the reaction is completed, sodium alcoholate / alcohol solution is added for neutralization until the pH of the system is 6-7, the solid is removed by filtration, and allyl triethoxysilane is obtained by distillation; S2, under ultraviolet light irradiation, allyltriethoxysilane, mercaptopropyltriethoxysilane and benzoin dimethyl ether obtained in step S1 are mixed and reacted at room temperature for 2-3 hours. Then, sulfur and a second catalyst are added and reacted at 80-90℃ for 1-2 hours. The mixture is then distilled at 100-110℃ and -0.07 to -0.06 MPa until no obvious bubbles are produced. After cooling, the mixture is filtered to obtain the final product.

[0005] In this invention, the allyltriethoxysilane obtained using the method in step S1 has high purity. This preparation method avoids the sulfur distribution fluctuations caused by the synthesis of sodium polysulfide aqueous solution and does not require the introduction of a phase transfer catalyst. Furthermore, the bis-[3-(triethoxysilyl)propyl]-disulfide obtained in this invention has low gaseous impurity content.

[0006] In a preferred embodiment of the present invention, in step S1, the molar ratio of allyl chloride to trichlorosilane is 1:(1.05~1.2).

[0007] In a preferred embodiment of the present invention, in order to improve the yield, in step S1, the molar ratio of tripropylamine to trichlorosilane is (1.05~1.2):1.

[0008] In a preferred embodiment of the present invention, the first catalyst is one or more of cuprous chloride, ferric chloride, cuprous oxide, and bismuth trichloride, preferably bismuth trichloride. The first catalyst is preferably 0.02 to 0.08 times the molar amount of allyl chloride.

[0009] In a preferred embodiment of the present invention, the alcohol is ethanol. The molar ratio of ethanol to allyl chloride is preferably (3.0~3.6):1. In a preferred embodiment of the present invention, the mixture of allyl chloride and trichlorosilane is added dropwise within 1~1.2 hours. Both excessively long and short addition times will affect the yield of allyltriethoxysilane.

[0010] In a specific embodiment of the present invention, after the addition is complete, the gas phase residue of allyl chloride in the clear liquid is used to determine the endpoint of the reaction. That is, the reaction is considered complete when the gas phase test of the clear liquid of the reaction system shows that the allyl chloride content does not exceed 0.5%. In the scheme of the present invention, the reaction is usually carried out for 2-3 hours until the gas phase test of the clear liquid shows that the allyl chloride content does not exceed 0.5%.

[0011] In a preferred embodiment of the present invention, the alcohol in the sodium alkoxide / alcohol solution is the same type as the saturated alcohol. If the saturated alcohol is methanol, then the sodium alkoxide / alcohol solution is a sodium methoxide / methanol solution; if the saturated alcohol is ethanol, then the sodium alkoxide / alcohol solution is a sodium ethoxide / ethanol solution. The sodium alkoxide / alcohol solution can be a commonly used sodium alkoxide / alcohol solution in the art, and its mass fraction can be the same as that of commercially available sodium alkoxide / alcohol solutions without affecting the effect of the present invention. The role of the sodium alkoxide / alcohol solution is to neutralize; the amount added is sufficient to neutralize the system to neutrality (system pH 6-7).

[0012] In an optional embodiment of the present invention, the non-polar solvent can be cyclohexane, n-hexane, petroleum ether, etc., and the amount of non-polar solvent can be the amount of solvent commonly used in the art, for example, 50% to 120% of the total amount of raw materials in the system.

[0013] In one specific embodiment of the present invention, in step S1, after filtering to remove the solid, allyltriethoxysilane can be obtained by distillation under normal pressure or reduced pressure.

[0014] In this invention, the yield of allyltriethoxysilane obtained by the method in step S1 can be as high as 90% or more, preferably as high as 93% or more.

[0015] In a preferred embodiment of the present invention, in step S2, the molar ratio of allyltriethoxysilane and mercaptopropyltriethoxysilane obtained in step S1 is 1:(1.02~1.05). Within this range, there are fewer byproducts and the product quality is good.

[0016] In step S2 of this invention, benzoin dimethyl ether acts as a catalyst. Compared with catalysts such as diphenyl ethyl ketone, benzophenone, and diaryl iodonium salt, the applicant unexpectedly discovered through numerous experiments that when using benzoin dimethyl ether, the reaction only needs 2-3 hours at room temperature (other catalysts require at least 5 hours and are less efficient). At the same time, under the synergistic effect of benzoin dimethyl ether, when sulfur is added, high-quality (narrow distribution, low gaseous impurity content) bis-[3-(triethoxysilyl)propyl]-disulfide can be generated by using triethylenediamine as a catalyst.

[0017] In the research of this invention, the applicant discovered during the experiment that in step S2, "mixing allyltriethoxysilane, mercaptopropyltriethoxysilane, and benzoin dimethyl ether and reacting at room temperature for 2-3 hours," when using gas phase testing to track the residual allyltriethoxysilane in the reaction system to determine the endpoint of the reaction (the allyltriethoxysilane content in the system is less than 0.3%), under the same conditions, when using benzoin dimethyl ether, only 2-3 hours of reaction are needed when the allyltriethoxysilane content in the system is less than 0.3%, while using other catalysts, at least 5 hours are required.

[0018] In a preferred embodiment of the present invention, the amount of benzoin dimethyl ether used is 1 to 3% of the total mass of the reactants in step S2 (i.e., the total mass of allyltriethoxysilane and mercaptopropyltriethoxysilane).

[0019] In a preferred embodiment of the present invention, in step S2, the molar ratio of the amount of sulfur to the allyltriethoxysilane is (1.01~1.25):1.

[0020] In a preferred embodiment of the present invention, in step S2, the second catalyst is triethylenediamine. The applicant has attempted to use catalysts such as diallylamine, diethylenetriamine, triethylenetetraamine, dicyclohexylamine, tetramethylethylenediamine, and triethylenediamine, but only the bis-[3-(triethoxysilyl)propyl]-disulfide obtained using triethylenediamine as a catalyst exhibits high quality after the addition of sulfur. In a preferred embodiment of the present invention, the second catalyst is preferably 1-3% by weight of sulfur.

[0021] In this invention, room temperature typically refers to 25~35°C.

[0022] Another object of the present invention is to provide a method for preparing a sulfur-containing silane, the method comprising mixing the bis-[3-(triethoxysilane)propyl]-disulfide obtained by the above preparation method, a third catalyst and a polyhydroxy compound, reacting at 80~90°C, distilling at -0.04MPa~-0.02MPa for 2~3 hours after the reaction is completed, and distilling at 120~140°C and -0.08MPa~-0.06MPa until no bubbles are generated.

[0023] In a preferred embodiment of the present invention, the polyhydroxy compound may be trimethylolpropane, glycerol, pentaerythritol, or triethanolamine. The molar ratio of the polyhydroxy compound to mercaptopropyltrialkoxysilane is preferably (1.2~1.6):1.

[0024] In an optional embodiment of the present invention, the third catalyst is a sodium alkoxide / alcohol solution, a solid acid, or other catalyst, wherein the alcohol in the sodium alkoxide / alcohol solution is of the same type as the alcohol in the polyhydroxy compound. Using the sulfur-containing silane obtained by the above preparation method as a coupling agent to prepare rubber can also effectively reduce premature scorching during rubber compounding.

[0025] The beneficial effects of this invention are as follows: The preparation method provided by this invention can successfully and effectively synthesize bis-[3-(triethoxysilane)propyl]-disulfide (disulfide content as high as 88% or more, low gaseous impurities (less than 1%, preferably less than 0.8%)). The preparation method provided by this invention can obtain bis-[3-(triethoxysilane)propyl]-disulfide with a narrow distribution. There are almost no small molecule impurities left in the entire preparation method. It avoids the sulfur distribution fluctuations caused by the synthesis of sodium polysulfide aqueous solution. It does not require the introduction of phase transfer catalyst catalysis, reduces the hydrolysis of silane and the treatment of brine, and has a high single-reactor synthesis yield and high equipment utilization. Detailed Implementation

[0026] The specific embodiments and comparative examples of the present invention will be described in further detail below. These typical embodiments and comparative examples are used to illustrate the present invention, but are not intended to limit the scope of the invention.

[0027] Unless otherwise specified in the embodiments of this invention, conditions shall be performed under conventional conditions or conditions recommended by the manufacturer. Reagents or instruments whose manufacturers are not specified are all commercially available conventional products. In this invention, unless otherwise specified, "%" refers to a percentage by mass.

[0028] Example 1 The method for preparing bis-[3-(triethoxysilyl)propyl]-disulfide provided in this embodiment includes the following steps: S1: Under nitrogen protection, 76.5g of allyl chloride and 149g of trichlorosilane were mixed evenly in a constant-pressure dropping funnel. At room temperature (30℃±2℃), the mixture of 130g of cyclohexane, 9.5g of bismuth chloride, and 165g of tripropylamine was added dropwise over 1 hour. Stirring continued at room temperature for 2 hours. The clear liquid was collected, and the allyl chloride content was determined to be 0.32% by gas chromatography. The filtrate was filtered and added dropwise to 157g of ethanol heated to 80℃ under micro-reflux conditions over 40 minutes. After the addition was complete, micro-reflux was maintained for approximately 1 hour. The temperature was lowered to below 50℃, and a 19% sodium ethoxide / ethanol solution was added to neutralize to pH 6.42. The mixture was filtered, and the fraction collected at 175~177℃ was distilled under normal pressure to obtain 190.4g of allyltriethoxysilane with a purity of 98.1%, yielding a yield of 93.2%.

[0029] S2: Under ultraviolet light irradiation, the obtained allyltriethoxysilane was mixed with 229g of mercaptopropyltriethoxysilane (purity 98.7%) and 5g of benzoin dimethyl ether at room temperature and stirred for 2h. 36g of sulfur and 0.72g of triethylenediamine were added, and the mixture was heated to 135~137℃ and kept at that temperature for 2h. The mixture was then cooled to 100~110℃ and subjected to -0.07~-0.06MPa until no obvious bubbles were generated. The mixture was then cooled to below 20℃ and filtered to obtain 450.3g of product.

[0030] The product is a bis-[3-(triethoxysilyl)propyl]-disulfide with a sulfur content of 14.51%, gaseous impurities of 0.52%, disulfide content of 88.3%, and an average sulfur chain length of 2.24. All other parameters of the product are within the specified range. The sulfur content, disulfide content, and gaseous impurities were tested according to GB / T 30309-2013, and the average sulfur chain length was calculated using the obtained sulfur distribution.

[0031] The specifications for the aqueous phase synthesis of bis-[3-(triethoxysilyl)propyl]-disulfide in the prior art are shown in Table 1 below: Table 1 ; Based on the data in Table 1, it can be seen that this embodiment successfully synthesized bis-[3-(triethoxysilyl)propyl]-disulfide, in which the disulfide content is as high as 88% or more, the gas phase impurities are low, the entire preparation method does not use aqueous phase synthesis, reduces the hydrolysis of silane and the treatment of brine, and does not introduce phase transfer catalyst catalysis.

[0032] Comparative Example 1 The preparation methods of this comparative example and Example 1 are the same, except that in step S2, 5g of diphenyl ethyl ketone is used instead of 5g of benzoin dimethyl ether, and 0.63g of cyclohexylamine is used instead of 0.72g of triethylenediamine.

[0033] This comparative example yielded a bis-[3-(triethoxysilyl)propyl]-disulfide with a sulfur content of 14.23%, gaseous impurities of 1.32%, disulfide content of 85.3%, and an average sulfur chain length of 2.31.

[0034] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 1, except that in step S2, 5g of benzophenone is used instead of 5g of benzoin dimethyl ether, and 0.78g of triethylenetetramine is used instead of 0.72g of triethylenediamine.

[0035] This comparative example yielded a bis-[3-(triethoxysilyl)propyl]-disulfide with a sulfur content of 16.1%, gaseous impurities of 3.13%, disulfide content of 83.6%, and an average sulfur chain length of 2.17.

[0036] Comparative Example 3 The preparation method of this comparative example is the same as that of Example 1, except that in step S2, 5g of 4,4′-diacetamidophenyliodohexafluorophosphate is used instead of 5g of benzoin dimethyl ether, and 0.7g of tetramethylethylenediamine is used instead of 0.72g of triethylenediamine.

[0037] The product obtained in this comparative example has a sulfur content of 15.4%, gaseous impurities of 21.73%, disulfide content of 81.4%, and an average sulfur chain length of 2.28, and is a bis-[3-(triethoxysilyl)propyl]-disulfide.

[0038] Experimental Example The product obtained in Example 1 was reacted with 85g of 8% sodium ethoxide / ethanol solution and 197g of triethanolamine (1.32mol) amine at 85°C for 1h. After removing alcohol by -0.03MPa to -0.02MPa for 2h, the temperature was slowly raised to 125~128°C and the pressure was reduced to -0.07MPa to -0.06MPa until no more bubbles were generated. After cooling, 409.2g of white powder was obtained.

[0039] This white powder was used as a coupling agent to prepare the compound. The compound preparation consisted of 100 parts natural rubber (NR), 30 parts silica, other industrial-grade rubber compounding agents (including 5 parts zinc oxide, 2 parts stearic acid, 1.5 parts N-tert-butyl-2-benzothiazole sulfenamide, 1 part diphenylguanidine, 1.5 parts N-isopropyl-N'-phenyl-p-phenylenediamine, 1 part sulfur, 2 parts CBS, and 2 parts DPG), plus 2 parts of the white powder coupling agent. The compound was prepared using a two-roll mill and then vulcanized using a hydraulic flat vulcanizing press for the specified vulcanization time t. 90 Vulcanization at 151 °C.

[0040] The scorch time was tested using a Mooney viscometer according to ASTM D1646-94; the Shore A hardness was tested on a hardness tester according to GB / T 531-83; the tensile properties were tested according to GB / T 528-92; and the tensile strength was tested on an electronic tensile testing machine according to GB / T 528-2009 at a tensile rate of 500 mm / min.

[0041] The properties of the obtained rubber compound are as follows: scorch time at 130℃ is 22.5 min, hardness is 62, tensile strength is 35.1 MPa, and tear strength is 105.73 kN·m. -1 .

[0042] Finally, the method of this invention is merely a preferred embodiment and is not intended to limit the scope of protection of this invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A method for preparing bis-[3-(triethoxysilyl)propyl]-disulfide, characterized in that, Includes the following steps: S1, Under nitrogen protection, a mixture of allyl chloride and trichlorosilane is added dropwise to a nonpolar solvent, a first catalyst, and tripropylamine. After the addition is complete, the mixture is reacted at room temperature until the allyl chloride content in the clear liquid is not more than 0.5% as determined by gas phase analysis. The mixture is then filtered and the filtrate is added dropwise to an alcohol under micro-reflux conditions. After the reaction is complete, a sodium alkoxide / alcohol solution is added to neutralize the system to a pH of 6-7. The solid is removed by filtration, and allyltriethoxysilane is obtained by distillation. S2, under ultraviolet light irradiation, allyltriethoxysilane, mercaptopropyltriethoxysilane and benzoin dimethyl ether obtained in step S1 are mixed and reacted at room temperature for 2-3 hours. Then, sulfur and a second catalyst are added and reacted at 80-90℃ for 1-2 hours. The mixture is then distilled at 100-110℃ and -0.07 to -0.06 MPa until no obvious bubbles are produced. After cooling, the mixture is filtered to obtain the final product.

2. The preparation method according to claim 1, characterized in that, In step S1, the molar ratio of allyl chloride to trichlorosilane is 1:(1.05~1.2), and the molar ratio of tripropylamine to trichlorosilane is (1.05~1.2):

1.

3. The preparation method according to claim 1, characterized in that, The first catalyst is one or more of cuprous chloride, ferric chloride, cuprous oxide, and bismuth trichloride, preferably bismuth trichloride; the amount of the catalyst is 0.02 to 0.08 times the molar amount of allyl chloride.

4. The preparation method according to claim 1, characterized in that, The alcohol is ethanol; the molar ratio of the alcohol to allyl chloride is (3.0~3.6):

1.

5. The preparation method according to claim 1, characterized in that, The nonpolar solvent is cyclohexane, n-hexane, or petroleum ether; and / or, the alcohol in the sodium alkoxide / alcohol solution is the same as the alcohol in the solution.

6. The preparation method according to any one of claims 1 to 5, characterized in that, In step S2, the molar ratio of allyltriethoxysilane to mercaptopropyltriethoxysilane is 1:(1.02~1.05), and the molar ratio of sulfur to allyltriethoxysilane is (1.01~1.25):

1.

7. The preparation method according to any one of claims 1 to 5, characterized in that, The amount of benzoin dimethyl ether used is 1-3% of the total mass of allyltriethoxysilane and mercaptopropyltriethoxysilane.

8. The preparation method according to any one of claims 1 to 5, characterized in that, In step S2, the second catalyst is triethylenediamine; the second catalyst is 1-3% by mass of sulfur.

9. A method for preparing a sulfur-containing silane, characterized in that, Includes the following steps: The bis-[3-(triethoxysilyl)propyl]-disulfide obtained by any one of claims 1 to 8, the third catalyst, and the polyhydroxy compound are mixed and reacted at 130 to 150 °C. After the reaction is completed, the mixture is distilled at -0.04 MPa to -0.02 MPa for 2 to 3 hours, and then distilled at 120 to 140 °C and -0.08 MPa to -0.06 MPa until no bubbles are generated.

10. The method for preparing sulfur-containing silanes according to claim 9, characterized in that, The polyhydroxy compound is trimethylolpropane, glycerol, pentaerythritol, or triethanolamine; The third catalyst is a sodium alkoxide / alcohol solution, wherein the alcohol in the sodium alkoxide / alcohol solution is of the same type as the alcohol in the polyhydroxy compound.