Method for synthesizing azosilane coupling agent by one-step method

Abstract

The invention discloses a method for synthesizing an azosilane coupling agent by a one-step method, which is characterized in that ureido silane and an amine compound are used as raw materials, and the azosilane coupling agent is synthesized in one step under the action of a catalyst, a cocatalyst and an initiator. The method is simple and easy to operate, low in reaction temperature, mild in operation condition, high in reaction rate, high in conversion rate and few in side reaction, the generated azosilane has high yield and purity, and industrial production is easy.

Description

Technical Field

[0001] This invention relates to a one-step method for synthesizing azosilane coupling agents, belonging to the field of chemical synthesis technology. Background Technology

[0002] Silane coupling agents are a class of low-molecular-weight organosilicon compounds with special structures, widely used in rubber, plastics, glass fibers, filled composites, epoxy encapsulation materials, elastomers, coatings, adhesives, and sealants. Due to their unique molecular structure, silane coupling agents can interact with both hydroxyl groups in inorganic materials and long molecular chains in organic polymers, coupling two materials with different properties and thus improving various properties of biomaterials. Therefore, silane coupling agents have become an indispensable additive in the materials industry.

[0003] However, for rubber products requiring high tensile strength and wear resistance, especially in tires and conveyor belts, silica is added as an effective reinforcing filler to improve the physical properties of the rubber products. Because silica contains a large number of silanol groups on its surface, it has high surface energy, can form hydrogen bonds, exhibits hydrophilicity, and is prone to agglomeration, leading to weakened rubber-filler interactions and reduced reinforcing effect. Furthermore, the silanol groups can delay rubber vulcanization. Therefore, surface modification of silica is necessary. Typically, silane coupling agents, after hydrolysis, can react with the hydroxyl groups of silica to reduce the number of hydroxyl groups, thereby improving the physical and mechanical properties of the composite material. Among these, azosilanes, with their unique azo structure, have unique applications in rubber modification.

[0004] Azo-silane coupling agents are disclosed in CN105504370A and CN105001252A, with the following chemical formula: There are two methods for preparing this azo-silane coupling agent. One method involves reacting hydrazine (such as ethyl hydrazine carbamate or phenylhydrazine) with isocyanate silane (such as 3-isocyanopropyl (triethoxysilane)) to obtain a precursor, which is then oxidized with an oxidant (such as NBS / pyridine) to obtain the final azo-silane coupling agent. The other method involves reacting hydrazine with acyl chloride, then oxidizing the reaction product with an oxidant, and finally reacting the oxidized product with an aminosilane to obtain the final azo-silane coupling agent. Both methods require expensive reagents such as isocyanate silanes and oxidants, resulting in high production costs. The yield of the obtained product is below 90%, and the yield and purity are low. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a one-step method for synthesizing azosilane coupling agents. This method uses ureosilane and amino compounds as raw materials to synthesize azosilane coupling agents in one step. The raw materials are simple and readily available, the cost is low, the process is concise, the side reactions are low, and the product yield is high.

[0006] The technical solution of this invention is as follows: A one-step method for synthesizing azosilane coupling agents, wherein the method uses ureosilane and amine compounds as raw materials, and synthesizes azosilane coupling agents having the structure shown in formula (Ⅰ) in one step under the action of a catalyst, a co-catalyst and an initiator: (I) in: --R1 is a hydroxyl group, C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl, C6-C 18 Aryl groups. Examples: -OH; -CH3; -CH2CH3; -(CH2)2CH3; -(CH2)3CH3; -(CH2)5CH3; -(CH2) 10 CH3; -(CH2) 15 CH3; -(CH2) 17 CH3;-O-CH3;-O-CH2CH3;-O-(CH2)2CH3;-O-(CH2)5CH3;-O-(CH2) 10 CH3;-O-(CH2) 17 CH3; -C5H9; -C6H 11 -C6H5; -CH2-C6H5; -C6H4-CH3, etc. Preferably, R1 is C1-C 18 The alkoxy group, more preferably a C1-C5 alkoxy group.

[0007] --R2 is a hydroxyl group, C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl, C6-C 18 Aryl groups. Examples: -CH3; -CH2CH3; -(CH2)2CH3; -(CH2)3CH3; -(CH2)5CH3; -(CH2) 10 CH3; -(CH2) 15 CH3; -(CH2) 17 CH3;-O-CH3;-O-CH2CH3;-O-(CH2)2CH3;-O-(CH2)5CH3;-O-(CH2) 10CH3;-O-(CH2) 17 CH3; -C5H9; -C6H 11 -C6H5; -CH2-C6H5; -C6H4-CH3, etc. Preferably, R2 is Cl-C 18 The alkoxy group, more preferably a C1-C5 alkoxy group.

[0008] --R3 is C1-C 18 Alkylene, C6-C 18 Aryl groups. Examples: -CH2-; -CH2CH2-; -CH2CH2CH2-; -(CH2)5-; -(CH2) 10 -;-(CH2) 15 -;-(CH2) 18 -; -C6H4-; -CH2-C6H4-; -C6H4-CH2-, etc. Preferably, R3 is C1-C 18 The alkylene group, more preferably a C1-C5 alkylene group.

[0009] --R4 is C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl, C6-C 18 The aryl, acyl, and ester groups can also be substituted acyl or ester groups. Examples: -CH3; -CH2CH3; -(CH2)2CH3; -(CH2)3CH3; -(CH2)5CH3; -(CH2) 10 CH3; -(CH2) 15 CH3; -(CH2) 17 CH3;-CH2-O-CH3;-CH2-O-CH2CH3;-CH2-O-(CH2)2CH3;-CH2-O-(CH2)5CH3;-CH2-O-(CH2) 10 CH3;-CH2-O-(CH2) 17 CH3; -C5H9; -C6H 11 -C6H5; -CH2-C6H5; -C6H4-CH3; -C(O)-CH3; -C(O)-CH2CH3; -CH2-C(O)-CH3; -C(O)-O-CH3; -C(O)-O-CH2CH3; -CH2-C(O)-O-CH3; -C(O)-CH2-O-CH3 (methoxyacetyl), etc. Preferably, R4 is C6-C 18 The aryl, C2-C6 acyl or C2-C6 ester group, more preferably phenyl, substituted phenyl, C2-C6 acyl or C2-C6 ester group; --R5 is either R1 or R2.

[0010] Furthermore, the synthesis method of the azosilane coupling agent includes the following steps: mixing ureosilane, amine compound, catalyst, co-catalyst and organic solvent 1, then adding dropwise a mixture of initiator and organic solvent 2 to the mixture, reacting after the addition is complete, and performing post-treatment after the reaction is completed to obtain the azosilane coupling agent.

[0011] Furthermore, the structural formula of the ureosilane is shown in Formula II below, and the definitions of R1, R2, R3, and R5 are consistent with those in Formula (I) above: II Furthermore, the structural formula of the amine compound is shown in Formula III: R4-NH2 (III), and the definition of R4 is consistent with the definition in Formula (I) above.

[0012] Furthermore, the reaction formulas for ureosilanes and amine compounds are as follows: Furthermore, the catalyst is a metallic element, such as one of copper, zinc, vanadium, bismuth, and tin.

[0013] Furthermore, the co-catalyst is one of sodium bromide, potassium bromide, sodium iodide, and potassium iodide.

[0014] Furthermore, the organic solvent 1 is one or more of dichloromethane, tetrahydrofuran, acetonitrile, methyl tert-butyl ether, etc.

[0015] Furthermore, the molar ratio of ureosilane to amine compound is 1:(1 to 1.2), for example 1:1, 1:1.1, 1:1.2.

[0016] Furthermore, the molar ratio of ureosilane to catalyst is 1:(0.1 to 0.5), for example 1:0.1, 1:0.2, 1:0.3, 1:0.4, 1:0.5.

[0017] Furthermore, the molar ratio of ureosilane to cocatalyst is 1:(0.2 to 1.2), for example 1:0.2, 1:0.3, 1:0.4, 1:0.5, 1:0.6, 1:0.7, 1:0.8, 1:0.9, 1:1.0, 1:1.1, and 1:1.2.

[0018] Furthermore, the mass ratio of ureosilane to organic solvent 1 is 1:(1-3), for example 1:1, 1:2, 1:3.

[0019] Furthermore, ureosilane, amine compounds, catalyst, co-catalyst, and organic solvent 1 are mixed at room temperature until homogeneous.

[0020] Furthermore, the initiator is one of tert-butyl hydroperoxide or di-tert-butyl peroxide.

[0021] Furthermore, the molar ratio of the initiator to the ureosilane is (0.2 to 1.2):1, for example, 0.2:1, 0.3:1, 0.4:1, 0.5:1, 0.6:1, 0.7:1, 0.8:1, 0.9:1, 1.0:1, 1.1:1, 1.2:1.

[0022] Furthermore, the organic solvent 2 is a mixture of solvent A and solvent B, wherein solvent A is one of dichloromethane, tetrahydrofuran, and methyl tert-butyl ether, preferably tetrahydrofuran; and solvent B is one of triethylamine or pyridine, preferably pyridine.

[0023] Furthermore, the mass ratio of solvent A to solvent B is (1-5):1, preferably 4:1.

[0024] Furthermore, in the mixture of initiator and organic solvent 2, the mass ratio of organic solvent 2 to initiator is (2-5):1, for example 2:1, 3:1, 4:1, 5:1.

[0025] Furthermore, the dropping temperature of the mixture of initiator and organic solvent 2 is 30℃~45℃, for example 30℃, 35℃, 40℃, 45℃, and the dropping time is 30min~60min, for example 30min, 40min, 60min.

[0026] Furthermore, after the mixture of initiator and organic solvent 2 is added, maintain the temperature at 35℃~55℃, for example 35℃, 40℃, 45℃, 50℃, 55℃, and continue the reaction for 2h~5h, for example 2h, 3h, 4h, 5h.

[0027] Furthermore, after the reaction, the reaction solution is post-treated to obtain the final product. The post-treatment process is as follows: the reaction solution is filtered to remove the solid catalyst and other solid by-products, then water is added and stirred for washing. After standing and separating, the organic phase is concentrated under reduced pressure to remove the organic solvent, thus obtaining the final azosilane coupling agent product.

[0028] Furthermore, the mass ratio of washing water to urea-silane is (0.5-3):1, preferably 1.5:1.

[0029] Furthermore, the temperature for vacuum concentration is 35℃~55℃, for example 35℃, 40℃, 45℃, 50℃, 55℃, and the pressure is -0.08 MPa~-0.1Mpa.

[0030] Furthermore, the entire reaction process is carried out under the protection of inert gases such as nitrogen and argon.

[0031] The present invention has the following beneficial effects: (1) The present invention uses ureosilane and amine compounds to synthesize azosilane coupling agent in one step. The method is simple and easy to operate, with high conversion rate. The generated azosilane has high purity and can be used alone or in combination with other types of coupling agents in rubber, especially tire rubber, which greatly improves the mechanical properties, weather resistance, dispersibility, molding properties and processability of rubber.

[0032] (2) The present invention uses metals such as copper, zinc, vanadium, bismuth and tin as catalysts, and sodium bromide, potassium bromide, sodium iodide and potassium iodide as co-catalysts. The azo synthesis reaction is initiated by free radicals generated by tert-butyl hydroperoxide and di-tert-butyl peroxide, which improves the catalytic activity. The catalytic system has few side reactions and high conversion rate.

[0033] (3) The present invention uses a mixed solvent as the organic solvent for the initiator, which improves the dispersibility of the reaction and provides a reaction medium for the reaction; on the other hand, triethylamine or pyridine can act as an acid-binding agent, which helps to capture the acid produced in the reaction, promote the forward reaction, and improve the yield of the reaction.

[0034] (4) The synthesis method provided by the present invention has a low reaction temperature, mild operating conditions, high reaction rate, few side reactions, high product yield and purity, and is easy to industrialize. Attached Figure Description

[0035] Figure 1 The image shows the liquid chromatogram of the product obtained in Example 1. Detailed Implementation

[0036] The following description illustrates exemplary embodiments of the present invention, including various details to aid understanding. These should be considered merely exemplary. Therefore, those skilled in the art will recognize that various changes and modifications can be made to the embodiments described herein without departing from the scope and spirit of the invention. Similarly, for clarity and brevity, descriptions of well-known functions, operations, and structures are omitted in the following description. Unless otherwise specified, the methods described in the following embodiments are conventional methods; the materials described, unless otherwise specified, are commercially available.

[0037] Unless otherwise specified, all concentrations mentioned in the following examples and comparative examples are mass percentage concentrations.

[0038] In the following examples and comparative examples, the product purity was determined by liquid chromatography, and the product yield was calculated using the following formula: Example 1 (Ⅰ-1) A method for synthesizing an azosilane coupling agent of formula (I-1) includes the following steps: (1) Under room temperature and inert gas protection, 100g of 3-ureapropyltriethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.), 38.75g of aniline, 8.66g of zinc powder, 27.31g of sodium bromide and 150g of tetrahydrofuran were added to the reaction vessel and mixed evenly to obtain mixed solution A. (2) Heat the reaction system to 35°C and add 85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine with a mass ratio of 4:1) to the mixed solution A in step (1). The addition time is 40min. After the addition is complete, heat the system to 50°C and reflux for 3.5h.

[0039] (3) After the reaction is completed, the solid catalyst and by-products are removed by filtration. Then, 150g of water is added to the filtrate for washing. After standing and separation, the organic phase is concentrated under reduced pressure at -0.09MPa and 50℃ to obtain 128.75g of the target product. The product is a reddish-brown oily liquid with a purity of 98.82% (liquid chromatography) and a yield of 95.15% based on ureosilane.

[0040] Example 2 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "38.75g aniline" was replaced with "42.27g aniline".

[0041] Example 3 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "8.66g zinc powder" was replaced with "8.42g copper powder".

[0042] Example 4 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "8.66g zinc powder" was replaced with "12.37g zinc powder".

[0043] Example 5 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "27.31g sodium bromide" was replaced with "46.82g sodium bromide".

[0044] Example 6 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "27.31g sodium bromide" was replaced with "39.74g sodium iodide".

[0045] Example 7 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (1), "8.66g zinc powder" was replaced with "15.74g tin powder" and "27.31g sodium bromide" was replaced with "31.55g potassium bromide".

[0046] Example 8 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (2), "85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1) was added to the mixed solution A in step (1)" instead of "138.27g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1) was added to the mixed solution A in step (1)".

[0047] Example 9 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that: in step (1), “150g tetrahydrofuran” was replaced with “150g dichloromethane”; in step (2), “85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1)” was replaced with “85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is dichloromethane and triethylamine in a mass ratio of 4:1)”.

[0048] Example 10 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that: in step (1), “150g tetrahydrofuran” was replaced with “150g methyl tert-butyl ether”; in step (2), “85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1)” was replaced with “85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is methyl tert-butyl ether and triethylamine in a mass ratio of 4:1)”.

[0049] Example 11 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (2), "85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1)" was replaced with "85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 1:1)".

[0050] Example 12 (Ⅰ-2) The azosilane coupling agent of formula (Ⅰ-2) was synthesized according to the method of Example 1, except that in step (1), "100g 3-ureapropyltriethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.) and 38.75g aniline" were replaced with "84.09g 3-ureapropyltrimethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.) and 57.08g m-aminophenethyl ether".

[0051] Example 13 (Ⅰ-3) The azosilane coupling agent of formula (Ⅰ-3) was synthesized according to the method of Example 1, except that in step (1), "38.75g aniline" was replaced with "47.92g 1-amino-3,3-dimethylbut-2-one".

[0052] Example 14 (Ⅰ-4) The azosilane coupling agent of formula (Ⅰ-4) was synthesized according to the method of Example 1, except that in step (1), "100g 3-ureapropyltriethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.) and 38.75g aniline" were replaced with "84.09g 3-ureapropyltrimethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.) and 31.25g methyl carbamate".

[0053] Comparative Example 1 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that zinc powder was not added in step (1).

[0054] Comparative Example 2 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that sodium bromide was not added in step (1).

[0055] Comparative Example 3 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that in step (2), "85.23g of 30% tert-butyl hydrogen peroxide solution (the organic solvent is tetrahydrofuran and pyridine in a mass ratio of 4:1)" was replaced with "73.06g of 35% tert-butyl hydrogen peroxide tetrahydrofuran solution, and 12.17g of sodium carbonate solid was added at the same time".

[0056] Comparative Example 4 The azosilane coupling agent of formula (Ⅰ-1) was synthesized according to the method of Example 1, except that no initiator was added in step (2).

[0057] Comparative Example 5 A method for synthesizing an azosilane coupling agent of formula (I-1) includes the following steps: (1) 100g of 3-ureapropyltriethoxysilane (manufacturer: Shanghai Aladdin Biochemical Technology Co., Ltd.), 38.75g of aniline, 8.66g of zinc powder, 27.31g of sodium bromide, 36.53g of 70% tert-butyl hydrogen peroxide solution, 12.17g of pyridine and 186.53g of tetrahydrofuran were added to the reaction vessel and mixed evenly. Then the reaction system was heated to 85℃ and reacted at this temperature for 3.5h.

[0058] (2) After the reaction is completed, the solid catalyst and by-products are removed by filtration. Then, 150g of water is added to the filtrate for washing. After standing and separating, the organic phase is concentrated under reduced pressure at -0.09MPa and 50℃ to obtain the target product.

[0059] The product details of the above embodiments and comparative examples are shown in Table 1 below: Table 1 The above description of the embodiments is only for the purpose of helping to understand the method and core ideas of the present invention. It should be noted that those skilled in the art can make several improvements and modifications to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A one-step method for synthesizing azosilane coupling agents, characterized in that: Using ureosilanes of Formula II and amines of Formula III as raw materials, azosilane coupling agents of Formula I are synthesized in the presence of catalysts, co-catalysts and initiators. In Formulas I, II, and III, R1 is a hydroxyl group, C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl or C6-C 18 The aryl group, preferably C1-C 18 The alkoxy group, more preferably a C1-C5 alkoxy group; R2 is a hydroxyl group, C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl or C6-C 18 The aryl group, preferably C1-C 18 The alkoxy group, more preferably a C1-C5 alkoxy group; R3 is C1-C 18 alkylene or C6-C 18 The arylene group, preferably C1-C 18 The alkylene group, more preferably a C1-C5 alkylene group; R4 is C1-C 18 Alkyl, C1-C 18 alkoxy groups, C5-C 18 cycloalkyl, C6-C 18 The aryl, acyl, or ester group, preferably C6-C 18 The aryl, C2-C6 acyl, or C2-C6 ester group; R5 is either R1 or R2.

2. The method according to claim 1, characterized in that: Urea-silane, amine compound, catalyst, co-catalyst and organic solvent 1 are mixed, and then a mixture of initiator and organic solvent 2 is added dropwise to the mixture. After the addition is complete, the reaction is carried out. After the reaction is completed, post-treatment is performed to obtain azosilane coupling agent.

3. The method according to claim 1 or 2, characterized in that: The catalyst is a metallic element, preferably one of copper, zinc, vanadium, bismuth, and tin; preferably, the co-catalyst is one of sodium bromide, potassium bromide, sodium iodide, and potassium iodide; preferably, the initiator is one of tert-butyl hydroperoxide or di-tert-butyl peroxide.

4. The method according to claim 1 or 2, characterized in that: The molar ratio of ureosilane to amine compound is 1:(1-1.2); preferably, the molar ratio of ureosilane to catalyst is 1:(0.1-0.5); preferably, the molar ratio of ureosilane to co-catalyst is 1:(0.2-1.2); preferably, the molar ratio of initiator to ureosilane is (0.2-1.2):

1.

5. The method according to claim 2, characterized in that: The organic solvent 1 is one or more of dichloromethane, tetrahydrofuran, acetonitrile, and methyl tert-butyl ether; preferably, the mass ratio of ureosilane to organic solvent 1 is 1:(1-3).

6. The method according to claim 2, characterized in that: The organic solvent 2 is a mixture of solvent A and solvent B. Solvent A is one of dichloromethane, tetrahydrofuran, and methyl tert-butyl ether, preferably tetrahydrofuran. Solvent B is one of triethylamine or pyridine, preferably pyridine. Preferably, the mass ratio of solvent A to solvent B is (1-5):

1.

7. The method according to claim 2 or 6, characterized in that: In step (2), the mass ratio of organic solvent 2 to initiator is (2-5):

1.

8. The method according to claim 2, characterized in that: In step (2), the dropping temperature of the mixture of initiator and organic solvent 2 is 30℃~45℃, and the dropping time is 30min~60min.

9. The method according to claim 2, characterized in that: In step (2), after the mixture of initiator and organic solvent 2 is added, the reaction continues at 35℃~55℃ for 2h~5h.

10. The method according to claim 1 or 2, characterized in that: In step (2), the entire reaction process is carried out under the protection of an inert gas.

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