A method for synthesizing a structurally symmetrical azosilane coupling agent

Abstract

The invention discloses a method for synthesizing a structurally symmetrical azosilane coupling agent, wherein aminosilane is used as a raw material, and firstly reacted with a carbonic acid diester compound under the action of a catalyst to obtain an aminoester silane; then the aminoester silane reacts with hydrazine hydrate to generate an azosilane coupling agent precursor; finally, the precursor is reacted with an oxidant to obtain a final target product. The raw materials of the invention are common and easily available, the price is low, the reaction temperature is not high, the operating conditions are mild, the reaction rate is high, the side reactions are few, the product yield and purity are high, the production cost is reduced, and it is easy to industrialize production.

Description

Technical Field

[0001] The invention relates to a method for synthesizing a structurally symmetrical azosilane coupling agent, belonging to the technical field of chemical synthesis. Background Art

[0002] Silane coupling agents are a class of low molecular weight organic silicon compounds with special structures, which are widely used in rubber, plastic, glass fiber, filling composite materials, epoxy packaging materials, elastomers, coatings, adhesives and sealants. Due to its special molecular structure, silane coupling agents can interact with both hydroxyl groups in inorganic substances and long molecular chains in organic polymers, coupling two materials with different properties, thereby improving various properties of biomaterials. Therefore, silane coupling agents have become one of the indispensable additives in the materials industry.

[0003] However, for rubber products that require high tensile strength and wear resistance, especially for tires and conveyor belts, etc., rubber products add silica as an effective reinforcing filler to improve the physical properties of rubber products. Since the surface of silica contains a large number of silanol groups, it has a high surface energy, can form hydrogen bonds, shows hydrophilicity, and is very easy to agglomerate with each other, resulting in a weakening of the rubber-filler interaction and a decrease in the reinforcement effect. Secondly, the hydroxyl groups will also cause the rubber to delay vulcanization. Therefore, it is necessary to modify the surface of silica. Generally, silane coupling agents can react with the hydroxyl groups of silica after hydrolysis to reduce the number of hydroxyl groups, thereby improving the physical and mechanical properties of the composite material. Among them, azosilane, with its unique azo structure, has a unique application in rubber modification.

[0004] CN105504370A and CN102822183A disclose an azo-silane coupling agent, the chemical formula of which is:

[0005] (R 1 ) 3-a (R 2 ) a Si-R I -NH-C(O)-N=NC(O)-NH-R I -Si(R 1 ) 3-a (R 2 ) a I,

[0006] The azo-silane coupling agent is obtained by reacting aminosilane with an azodicarboxyl compound (such as diisopropyl azodicarboxylate) in an organic solvent. The raw materials used in this method are expensive, the production cost is high, and the purity of the obtained product is low. Summary of the invention

[0007] In view of the shortcomings of the prior art, the present invention provides a method for synthesizing a structurally symmetrical azosilane coupling agent. The raw materials used in the method are common and easily available, the reaction conditions are mild, the reaction efficiency is high, the product yield and purity are high, the production cost is low, and the method is suitable for large-scale industrial production.

[0008] The structurally symmetrical azosilane coupling agent of the present invention has the structural formula described in the following formula (I):

[0009] (R 1 ) x (R 2 ) 3-x -Si-R 3 -NH-C(O)-N=NC(O)-NH-R 3 -Si-(R 1 ) x (R 2 ) 3-x (Ⅰ)

[0010] in:

[0011] --R 1 is hydroxyl group, C 1 -C 18 Alkyl, C 1 -C 18 Alkoxy, C 5 -C 18 Cycloalkyl, C 6 -C 18 For example: -OH; -CH 3 ; -CH 2 CH 3 ;-(CH 2 ) 2 CH 3 ;-(CH 2 ) 5 CH 3 ;-(CH 2 ) 10 CH 3 ;-(CH 2 ) 15 CH 3 ;-(CH 2 ) 17 CH 3 ;-O-CH 3 ;-O-CH 2 CH 3 ;-O-(CH 2 ) 2 CH 3 ;-O-(CH 2 ) 5 CH 3;-O-(CH 2 ) 10 CH 3 ;-O-(CH 2 ) 17 CH 3 ;-C 5 H 9 ;-C 6 H 11 ;-C 6 H 5 ; -CH 2 -C 6 H 5 ;-C 6 H 4 -CH 3 wait.

[0012] --R 2 C 1 -C 18 Alkyl, C 1 -C 18 Alkoxy, C 5 -C 18 Cycloalkyl, C 6 -C 18 For example: -CH 3 ; -CH 2 CH 3 ;-(CH 2 ) 2 CH 3 ;-(CH 2 ) 3 CH 3 ;-(CH 2 ) 5 CH 3 ;-(CH 2 ) 10 CH 3 ;-(CH 2 ) 15 CH 3 ;-(CH 2 ) 17 CH 3 ;-O-CH 3 ;-O-CH 2 CH 3 ;-O-(CH 2 ) 2 CH 3 ;-O-(CH 2 ) 5 CH 3 ;-O-(CH 2 ) 10 CH 3 ;-O-(CH2 ) 17 CH 3 ;-C 5 H 9 ;-C 6 H 11 ;-C 6 H 5 ; -CH 2 -C 6 H 5 ;-C 6 H 4 -CH 3 wait.

[0013] --x is equal to 1, 2, or 3.

[0014] --R 3 C 1 -C 18 Alkylene, C 6 -C 18 For example: -CH 2 -;-CH 2 CH 2 -;-CH 2 CH 2 CH 2 -;-(CH 2 ) 5 -;-(CH 2 ) 10 -;-(CH 2 ) 15 -;-(CH 2 ) 18 -;-C 6 H 4 -;-CH 2 -C 6 H 4 -;-C 6 H 4 -CH 2 -wait.

[0015] The method for synthesizing the structurally symmetrical azosilane coupling agent of the present invention comprises the following steps:

[0016] (1) using an aminosilane of formula (II) as a raw material, first reacting it with a carbonic acid diester compound of formula (III) under the action of a catalyst to obtain an amino ester silane of formula (IV);

[0017] (2) then reacting the amino ester silane of formula (IV) with hydrazine hydrate to generate an azosilane coupling agent precursor of formula (V);

[0018] (3) Finally, the azosilane coupling agent precursor of formula (V) is oxidatively dehydrogenated under the action of an oxidant to obtain the final target product, a structurally symmetrical azosilane coupling agent of formula (I).

[0019] Furthermore, in step (1), the structural formula of the aminosilane is:

[0020] (R 1 ) x (R 2 ) 3-x -Si-R 3 -NH 2 (Ⅱ)

[0021] In formula (II), R 1 , R 2 , R 3 The definitions of and x are the same as those in the above formula (I).

[0022] Furthermore, in step (1), the structural formula of the carbonic acid diester compound is:

[0023] CH 3 -(CH 2 ) y -OC(O)-O-(CH 2 ) y -CH 3 (III)

[0024] In formula (III), y is equal to 0, 1, 2, 3, 4, etc.

[0025] Furthermore, in step (1), the structural formula of the aminoester silane obtained is:

[0026] (R 1 ) x (R 2 ) 3-x -Si-R 3 -NH-C(O)-O-(CH 2 ) y -CH 3 (IV)

[0027] In formula (IV), R 1 , R 2 , R 3 The definitions of x and y are the same as those in the above formula (I), and the definitions of y are the same as those in the above formula (III).

[0028] Furthermore, in step (1), the aminosilane of formula (II) undergoes a substitution reaction with the carbonic acid diester compound of formula (III), and the molar ratio of the aminosilane of formula (II) to the carbonic acid diester compound of formula (III) is 1:(1-1.2), for example, 1:1, 1:1.1, 1:1.2.

[0029] Furthermore, in step (1), the catalyst is an ethanol solution of sodium ethoxide with a mass fraction of 25% to 30%, and the mass ratio of the ethanol solution of sodium ethoxide with a mass fraction of 25% to 30% to the aminosilane of formula (II) is (2% to 5%):1, for example, 2%:1, 3%:1, 4%:1, 5%:1. The catalyst is sodium ethoxide. Since sodium ethoxide is relatively active, it will quickly decompose into sodium hydroxide and ethanol when dissolved in water, and is relatively stable in ethanol solution. Therefore, it is selected to be added in the form of ethanol solution. The sodium ethoxide ethanol solution of this concentration is convenient for feeding and makes the reaction more gentle.

[0030] Furthermore, in step (1), there is no special requirement for the order of adding the raw materials, and the raw materials can be mixed together, or the raw materials can be mixed first and then the catalyst can be added, or one raw material can be added first, then another raw material, and then the catalyst. Preferably, the catalyst is added dropwise.

[0031] Further, in step (1), the reaction temperature is -10°C to -25°C, for example, -10°C, -11°C, -12°C, -13°C, -14°C, -15°C, -16°C, -17°C, -18°C, -19°C, -20°C, -21°C, -22°C, -23°C, -24°C, -25°C, and the reaction time is 15 min to 45 min, for example, 15 min, 20 min, 25 min, 30 min, 35 min, 40 min, 45 min.

[0032] Furthermore, in step (1), after the reaction is completed, a quencher is added to terminate the reaction, and the quencher is liquid pure acetic acid, and the mass ratio of acetic acid to the aminosilane of formula (II) is (0.3% to 2%):1, for example, 0.3%:1, 0.5%:1, 1%:1, 1.5%:1, 2%:1.

[0033] Furthermore, in step (1), the temperature of the quenching reaction is 20°C to 30°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, and the time of the quenching reaction is 5 min to 15 min, for example, 5 min, 10 min, 15 min.

[0034] Furthermore, in step (2), the structural formula of the azosilane coupling agent precursor obtained is:

[0035] (R 1 )x (R 2 ) 3-x -Si-R 3 -NH-C(O)-NH-NH-C(O)-NH-R 3 -Si-(R 1 ) x (R 2 ) 3-x (V)

[0036] In formula (V), R 1 , R 2 , R 3 The definitions of and x are the same as those in the above formula (I).

[0037] Furthermore, in step (2), hydrazine hydrate is present in the form of a solution, preferably a high concentration hydrazine hydrate solution, such as 75-85 wt %.

[0038] Furthermore, in step (2), the molar ratio of hydrazine hydrate to the aminosilane of formula (II) is (1-1.1):1.

[0039] Furthermore, in step (2), the reaction is carried out in the presence of an organic solvent, and the organic solvent as the reaction medium can be selected from at least one of dichloromethane, tetrahydrofuran, N,N-dimethylamide, acetonitrile, etc. The mass ratio of the organic solvent to the hydrazine hydrate solution is (2 to 6):1, for example, 2:1, 3:1, 4:1, 5:1, 6:1.

[0040] Furthermore, the product obtained in step (1) does not need to be separated and can be directly used in the next step. In step (2), preferably, the hydrazine hydrate solution is first mixed with an organic solvent, and then the reaction solution of step (1) is added dropwise to the resulting mixture.

[0041] Further, in step (2), the reaction temperature is 40°C to 60°C, for example 40°C, 45°C, 50°C, 55°C, 60°C. The reaction time is 30min to 2h, for example 30min, 35min, 40min, 45min, 50min, 55min, 60min, 65min, 70min, 75min, 80min, 85min, 90min, 95min, 100min, 105min, 110min, 115min, 120min.

[0042] Furthermore, in step (2), after the reaction, water in the reaction solution is removed, and the dehydration method can be distillation, vacuum distillation, adding a dehydrating agent, etc., preferably adding a dehydrating agent. The dehydrating agent is preferably a water-absorbing resin, such as SAP superabsorbent resin, and examples thereof include polyacrylate, starch acrylate polymer, starch-acrylonitrile graft copolymer, acrylamide-acrylonitrile-acrylic acid terpolymer, etc. Preferably, the mass ratio of the dehydrating agent to the hydrazine hydrate solution is (3% to 8%): 1, such as 3%: 1, 4%: 1, 5%: 1, 6%: 1, 7%: 1, 8%: 1. After dehydration, the resin is filtered to remove the resin, and the filtrate does not need to be extracted and separated from the azosilane coupling agent precursor, and can be directly used in the next step of the reaction.

[0043] Further, in step (3), the oxidant is one of dichloroisocyanuric acid (TCCA) / acid-binding agent oxidation system, sodium bromide / chlorine / acid-binding agent oxidation system, diacetoxyphenyliodide (PIDA), bis(trifluoroacetoxy)phenyliodide (PIFA), etc. Among them, the acid-binding agent can be an alkaline substance such as pyridine and triethylamine.

[0044] Further, in step (3), when the oxidant is a dichloroisocyanuric acid (TCCA) / acid binding agent oxidation system, dichloroisocyanuric acid (TCCA) acts as an oxidant, and the acid binding agent can better promote the oxidation reaction. The molar ratio of dichloroisocyanuric acid (TCCA) to hydrazine hydrate is (0.5-2.5):1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, and the mass ratio of the acid binding agent to the hydrazine hydrate solution is (5%-10%):1, for example, 5%:1, 6%:1, 7%:1, 8%:1, 9%:1, 10%:1.

[0045] Further, in step (3), when the oxidant is a sodium bromide / chlorine / acid binding agent oxidation system, sodium bromide acts as an oxidant, and chlorine and acid binding agent can better promote the oxidation reaction. The molar ratio of sodium bromide to hydrazine hydrate is (0.5-2.5):1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1, chlorine is continuously introduced into the reaction system, and the pressure in the reaction system is ensured to be below 0.1Mpa to ensure safety. The mass ratio of acid binding agent to hydrazine hydrate solution is (5%-10%):1, for example, 5%:1, 6%:1, 7%:1, 8%:1, 9%:1, 10%:1.

[0046] Furthermore, in step (3), the molar ratio of diacetoxyphenyliodoacetyl (PIDA) to hydrazine hydrate is (0.5-2.5):1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1.

[0047] Furthermore, in step (3), the molar ratio of bis(trifluoroacetoxy)phenyliodoacetyl (PIFA) to hydrazine hydrate is (0.5-2.5):1, for example, 0.5:1, 1:1, 1.5:1, 2:1, 2.5:1.

[0048] Furthermore, in step (3), there is no special requirement for the mixing order of the reactants. Preferably, dichloroisocyanuric acid (TCCA), diacetoxyphenyliodoacetyl (PIDA), and bis(trifluoroacetoxy)phenyliodoacetyl (PIFA) are added in the form of an organic solvent solution, and sodium bromide is added in the form of a solid powder. The organic solvent used can be at least one of dichloromethane, tetrahydrofuran, N,N-dimethylformamide, acetonitrile, etc.

[0049] Furthermore, in step (3), the reaction temperature is 20°C to 35°C, for example, 20°C, 21°C, 22°C, 23°C, 24°C, 25°C, 26°C, 27°C, 28°C, 29°C, 30°C, 31°C, 32°C, 33°C, 34°C, 35°C, and the reaction time is 30min to 60min, for example, 30min, 35min, 40min, 45min, 50min, 55min, 60min.

[0050] Furthermore, in step (3), after the reaction is completed, the reaction solution is post-treated to obtain the final product, and the post-treatment includes: recovering the organic solvent by vacuum rotary evaporation, washing the residue with a detergent, filtering after washing, and vacuum rotary evaporating the filtrate to remove the detergent to obtain the final product.

[0051] Furthermore, in step (3), the detergent is a mixture of heptane and isopropyl ether (volume ratio is 1:1), and the mass of the mixture of heptane and isopropyl ether and the mass of the azosilane coupling agent precursor of formula (VI) are (0.5-2):1, for example, 0.5:1, 1:1, 1.5:1, 2:1.

[0052] Furthermore, in step (3), the drying temperature of the two vacuum rotary evaporation dryings is 55°C to 65°C, the drying pressure is -0.08MPa to -0.1MPa, and the drying time is 0.5h to 3h. The purpose of the first vacuum rotary evaporation drying is to remove the organic solvent, and the purpose of the second vacuum rotary evaporation drying is to remove the detergent (a mixture of heptane and isopropyl ether).

[0053] Furthermore, in steps (1), (2) and (3), the reaction processes are all carried out under the protection of an inert gas such as nitrogen.

[0054] The present invention has the following beneficial effects:

[0055] (1) The present invention uses aminosilane as a raw material, first reacts with a carbonic acid diester compound to generate a corresponding amino ester silane, then reacts with hydrazine hydrate to generate a precursor, and finally oxidatively dehydrogenates under the action of an oxidant to obtain a target structurally symmetrical azo silane coupling agent. In this synthesis method, various raw materials are common and easy to obtain, and the cost of raw materials is low. Compared with the route of directly reacting aminosilane with azodicarboxylate, the reaction cost is low, and it is more conducive to industrial production.

[0056] (2) The present invention uses an ethanol solution of sodium ethoxide as a strong catalyst for both the first and second step reactions, which helps to improve the reaction efficiency, while also improving the utilization rate of raw materials, shortening the reaction time, and reducing production costs.

[0057] (3) The oxidant used in the present invention is one of dichloroisocyanuric acid (TCCA) / acid-binding agent oxidation system, sodium bromide / chlorine / acid-binding agent oxidation system, diacetoxyphenyliodide (PIDA), and bis(trifluoroacetoxyphenyliodide) (PIFA). The oxidation system has a low price, high oxidation efficiency, short reaction time, and a milder and more controllable oxidation process, so that the oxidation reaction proceeds more thoroughly in the forward direction. Among them, the more preferred oxidant is dichloroisocyanuric acid (TCCA) / acid-binding agent oxidation system, because the oxidant not only has a high oxidation efficiency, but is also cheap and easy to obtain, and the obtained structurally symmetrical azo silane coupling agent has a higher yield and product purity.

[0058] (4) The synthesis method of the present invention has low reaction temperature, mild operating conditions, high reaction rate, few side reactions, high product yield and purity, and is easy for industrial production.

[0059] (5) The structurally symmetrical azo silane coupling agent obtained by the present invention 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, formability and process operability of the rubber. DETAILED DESCRIPTION

[0060] The following is a description of exemplary embodiments of the present invention, including various details of the embodiments of the present invention to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present invention. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions, operations and structures are omitted in the following description. The methods described in the following embodiments, unless otherwise specified, are conventional methods; the materials, unless otherwise specified, can be obtained from commercial sources.

[0061] In the following examples and comparative examples, unless otherwise specified, the concentrations are all mass percentage concentrations.

[0062] Example 1

[0063] (CH 3 -0) 3 -Si-(CH 2 ) 3 -NH-C(O)-N=NC(O)-NH-(CH 2 ) 3 -Si-(0-CH 3 ) 3 (Ⅰ-1)

[0064] A method for synthesizing a structurally symmetrical azosilane coupling agent of formula (I-1), comprising the following steps:

[0065] 1) 100 g of 3-aminopropyltrimethoxysilane and 72.51 g of diethyl carbonate were added to a reactor at the same time, and the reactor was placed under a nitrogen atmosphere; when the system temperature was reduced to -15°C, 3 g of an ethanol solution of sodium ethoxide with a mass fraction of 25% was added dropwise to the reactor, and the mixture was reacted at a temperature of -13°C to -18°C for 20 min; after the reaction was completed, the temperature was raised to 25°C, and 0.8 g of acetic acid was added to quench the reaction for 5 min to obtain a mixture containing [3-(trimethoxysilyl)propyl]ethyl carbamate.

[0066] 2) At room temperature, 36.66g of hydrazine hydrate with a mass fraction of 80% was dissolved in 100g of tetrahydrofuran, and then placed in a clean reactor, and the reactor was placed in a nitrogen atmosphere; at 45°C, the mixture containing [3-(trimethoxysilyl)propyl]urethane obtained in step 1) was added dropwise to the reactor, and the temperature was controlled to be 45°C to 50°C, and the reaction was carried out in this temperature range for 90min. Then the reaction system was cooled to room temperature, and 1.5g of SAP super absorbent resin was added to the reaction system, and the reaction was filtered after stirring for 15min to fully remove the water in the reaction solution. The filtrate was a tetrahydrofuran solution of azosilane precursor.

[0067] 3) Add 3g of pyridine to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere, then add 158.77g of a 60% tetrahydrofuran solution of dichloroisocyanuric acid (TCCA) to the reactor at 25°C, and react at room temperature for 45min. After the reaction is completed, the organic solvent is recovered by vacuum rotary drying at 60°C and a vacuum degree of 0.09MPa, and the residual paste is washed with a mixture of heptane and isopropyl ether (volume ratio of 1:1), and then filtered. The filtrate is vacuum rotary dried at 60°C and a vacuum degree of 0.09MPa to obtain the final structurally symmetrical azosilane product as shown in formula (I-1), which has the appearance of a red oily liquid.

[0068] Example 2

[0069] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (1), "3 g of an ethanol solution of sodium ethoxide with a mass fraction of 25% was added dropwise to the reaction kettle" was replaced by "5 g of an ethanol solution of sodium ethoxide with a mass fraction of 25% was added dropwise to the reaction kettle".

[0070] Example 3

[0071] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that in step (2), "36.66 g of 80% by mass hydrazine hydrate was dissolved in 100 g of tetrahydrofuran" was replaced by "36.66 g of 80% by mass hydrazine hydrate was dissolved in 100 g of dichloromethane".

[0072] Example 4

[0073] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (2), "36.66 g of 80% hydrazine hydrate was dissolved in 100 g of tetrahydrofuran" was replaced by "38.41 g of 80% hydrazine hydrate was dissolved in 100 g of tetrahydrofuran", and in step (3), "158.77 g of 60% dichloroisocyanuric acid (TCCA) in tetrahydrofuran was then added dropwise to the reaction kettle at 25°C" was replaced by "166.33 g of 60% dichloroisocyanuric acid (TCCA) in tetrahydrofuran was then added dropwise to the reaction kettle at 25°C".

[0074] Example 5

[0075] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that in step (2), "and 1.5 g of SAP super absorbent resin was added to the reaction system, stirred for 15 min and filtered" was replaced by "and 3 g of SAP super absorbent resin was added to the reaction system, stirred for 15 min and filtered".

[0076] Example 6

[0077] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "then 158.77 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran was added dropwise to the reaction kettle at 25°C" was replaced by "then 317.52 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran was added dropwise to the reaction kettle at 25°C".

[0078] Example 7

[0079] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "adding 3 g of pyridine to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere" was replaced by "adding 3 g of triethylamine to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere".

[0080] Example 8

[0081] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "then 158.77 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran was added dropwise to the reactor at 25°C" was replaced by "then 42.29 g of sodium bromide solid was added to the reactor at 25°C, and chlorine gas was continuously bubbled into the bottom of the reactor to maintain the pressure in the reactor below 0.1 MPa".

[0082] Example 9

[0083] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "adding 3 g of pyridine to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere, and then adding dropwise 158.77 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran to the reaction kettle at 25°C" was replaced by "adding dropwise 220.36 g of a 60% by mass solution of diacetoxyphenyliodoacetate (PIDA) in tetrahydrofuran to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere at 25°C".

[0084] Example 10

[0085] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "3 g of pyridine was added to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere, and then 158.77 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran was added dropwise to the reaction kettle at 25°C" was replaced by "294.27 g of a 60% by mass solution of bis(trifluoroacetoxy)phenyliodoacetyl (PIFA) in tetrahydrofuran was added dropwise to the tetrahydrofuran solution of the azosilane precursor obtained in step 2) under a nitrogen atmosphere at 25°C".

[0086] Embodiment 11

[0087] (CH 3 ) 3 -Si-(CH 2 )3 -NH-C(O)-N=NC(O)-NH-(CH 2 ) 3 -Si-(CH 3 ) 3 (Ⅰ-2)

[0088] A structurally symmetrical azosilane coupling agent of formula (I-2) was synthesized according to the method of Example 1, except that: in step (1), "100 g of 3-aminopropyltrimethoxysilane and 72.51 g of diethyl carbonate were added to the reaction kettle at the same time, and the reaction kettle was placed under a nitrogen atmosphere" was replaced by "73.18 g of 3-aminopropyltrimethylsilane and 72.51 g of diethyl carbonate were added to the reaction kettle at the same time, and the reaction kettle was placed under a nitrogen atmosphere".

[0089] Comparative Example 1

[0090] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (1), "after the reaction is completed, the temperature is raised to 25°C, and 0.8 g of acetic acid is added to quench the reaction for 5 minutes" is replaced by "after the reaction is completed, the temperature is raised to 25°C and the reaction is carried out for 5 minutes".

[0091] Comparative Example 2

[0092] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (3), "then 158.77 g of a 60% by mass solution of dichloroisocyanuric acid (TCCA) in tetrahydrofuran was added dropwise to the reaction kettle at 25°C" was replaced by "then 121.82 g of a 60% by mass solution of N-bromosuccinimide (NBS) in tetrahydrofuran was added dropwise to the reaction kettle at 25°C".

[0093] Comparative Example 3

[0094] The structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Comparative Example 2, except that: in step (2), "36.66 g of hydrazine hydrate with a mass fraction of 80% was dissolved in 100 g of tetrahydrofuran" was replaced by "36.66 g of hydrazine hydrate with a mass fraction of 80% was dissolved in 100 g of dichloromethane".

[0095] Comparative Example 4

[0096] A structurally symmetrical azosilane coupling agent of formula (I-1) was synthesized according to the method of Example 1, except that: in step (1), "when the system temperature is lowered to -15°C, 3 g of 25% sodium ethoxide ethanol solution is added dropwise to the reaction kettle, and the mixture is reacted at a temperature of -13°C to -18°C for 20 min" is replaced by "when the system temperature is lowered to -13°C to -18°C, the mixture is reacted at this temperature for 20 min".

[0097] The purity of the structurally symmetrical azosilane coupling agents obtained in the examples of the present invention and the comparative examples was detected by gas chromatography, and the yield was calculated by the following formula. The specific results are shown in Table 1.

[0098]

[0099] Table 1

[0100] Appearance quality purity Yield Example 1 Red oily liquid 238.77g 96.72％ 93.95％ Example 2 Red oily liquid 238.24g 96.16％ 93.20％ Example 3 Red oily liquid 237.32g 95.95％ 92.64％ Example 4 Red oily liquid 237.85g 95.78％ 92.68％ Example 5 Red oily liquid 237.53g 96.29％ 93.05％ Example 6 Red oily liquid 238.16g 96.06％ 93.07％ Example 7 Red oily liquid 237.79g 96.39％ 93.25％ Example 8 Red oily liquid 237.86g 96.48％ 93.36％ Example 9 Red oily liquid 237.92g 96.11％ 93.03％ Example 10 Red oily liquid 237.76g 96.05％ 92.90％ Embodiment 11 Red oily liquid 187.42g 96.25％ 93.87％ Comparative Example 1 Red oily liquid 237.56g 91.17％ 88.11％ Comparative Example 2 Red oily liquid 233.92g 92.33％ 87.86％ Comparative Example 3 Red oily liquid 232.01g 90.73％ 85.64％ Comparative Example 4 Reddish brown oily liquid 229.92g 84.57％ 79.10％

[0101] The above embodiments are only used to help understand the method and core idea of ​​the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A method for synthesizing a structurally symmetrical azosilane coupling agent, characterized in that include: In the first step, aminosilane of formula (II) (R1) x (R2) 3-x -Si-R3-NH2(Ⅱ) With the carbonic acid diester compound of formula (III) CH3-(CH2) y -OC(O)-O-(CH2) y -CH3(Ⅲ) Under the action of a catalyst, an amino ester silane of formula (IV) is obtained: (R1) x (R2) 3-x -Si-R3-NH-C(O)-O-(CH2) y -CH3(Ⅳ); In the second step, the amino ester silane of formula (IV) reacts with hydrazine hydrate to obtain an azosilane coupling agent precursor of formula (V): (R1) x (R2) 3-x -Si-R3-NH-C(O)-NH-NH-C(O)-NH-R3-Si-(R1) x (R2) 3-x (Ⅴ); In the third step, the azosilane coupling agent precursor of formula (V) is reacted with an oxidant to obtain a structurally symmetrical azosilane coupling agent of formula (I): (R1) x (R2) 3-x -Si-R3-NH-C(O)-N=NC(O)-NH-R3-Si-(R1) x (R2) 3-x (Ⅰ); In formula (I), formula (II), formula (III), formula (IV) and formula (V), R1 is hydroxyl, C1-C 18 Alkyl, C1-C 18 Alkoxy, C5-C 18 Cycloalkyl, C6-C 18 The aromatic group; R2 is C1-C 18 Alkyl, C1-C 18 Alkoxy, C5-C 18 Cycloalkyl, C6-C 18 The aromatic group; R3 is C1-C 18 Alkylene, C6-C 18 arylene; x is an integer from 1 to 3; y is an integer from 0 to 4.

2. The synthesis method according to claim 1, characterized in that: R1 is -OH; -CH3; -CH2CH3; <h2 style=";text-align:left;direction:ltr">-(CH2)2CH3;-(CH2)5CH3;-(CH2)<h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> CH3;-(CH2)<h2 style=";text-align:left;direction:ltr"> 15 <h2 style=";text-align:left;direction:ltr"> CH3;-(CH2)<h2 style=";text-align:left;direction:ltr"> 17 <h2 style=";text-align:left;direction:ltr"> CH3;-O-CH3; <h2 style=";text-align:left;direction:ltr">-O-CH2CH3;-O-(CH2)2CH3;-O-(CH2)5CH3;-O-(CH2)<h2 style=";text-align:left;direction:ltr"> 10 <h2 style=";text-align:left;direction:ltr"> CH3;-O-(CH2)<h2 style=";text-align:left;direction:ltr"> 17 <h2 style=";text-align:left;direction:ltr"> CH3;-C5H9; -C6H 11 ;-C6H5;-CH2-C6H5;-C6H4-CH3; R2 is -CH3; -CH2CH3; -(CH2)2CH3; -(CH2)3CH3; -(CH2)5CH3; -(CH2) 10 CH3; <h2 style=";text-align:left;direction:ltr">-(CH2)<h2 style=";text-align:left;direction:ltr"> 15 <h2 style=";text-align:left;direction:ltr"> CH3;-(CH2)<h2 style=";text-align:left;direction:ltr"> 17 <h2 style=";text-align:left;direction:ltr"> 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; R3 is -CH2-; -CH2 CH2-; -CH2CH2CH2-; -(CH2)5-; -(CH2) 10 -; -(CH2) 15 -; -(CH2) 18 -;-C6H4-;-CH2-C6H4-;-C6H4-CH2-。 3. The synthesis method according to claim 1, characterized in that: in the first step, at least one of the following conditions is included: Condition 1: The molar ratio of the aminosilane of formula (II) to the carbonic acid diester compound of formula (III) is 1: (1～1.2)； Condition 2: The catalyst is an ethanol solution of sodium ethoxide with a mass fraction of 25% to 30%; Condition 3, the reaction temperature is -10°C to -25°C; Condition 4: The reaction time is 15 min to 45 min.

4. The synthesis method according to claim 3 is characterized in that: in the first step, the mass ratio of the ethanol solution of sodium ethoxide with a mass fraction of 25% to 30% to the aminosilane of formula (II) is (2% to 5%):

1.

5. The synthesis method according to claim 1, characterized in that: in the second step, at least one of the following conditions is included: Condition 1: The molar ratio of hydrazine hydrate to the aminosilane of formula (II) is (1-1.1):1; Condition 2: hydrazine hydrate exists in the form of a solution, and the concentration of the hydrazine hydrate solution is 75-85wt%; Condition 2: The reaction is carried out in the presence of an organic solvent, and the organic solvent is preferably at least one of dichloromethane, tetrahydrofuran, N,N-dimethylamide and acetonitrile; Condition 3, the reaction temperature is 40°C to 60°C; Condition 4: Reaction time is 30 min to 2 h.

6. The synthesis method according to claim 1, characterized in that: in the third step, the oxidant is one of dichloroisocyanuric acid / acid binding agent oxidation system, sodium bromide / chlorine / acid binding agent oxidation system, diacetoxybenzyl iodide, and bis(trifluoroacetoxy)benzyl iodide.

7. The synthesis method according to claim 6 is characterized in that: in the third step, the ratio of the molar amount of dichloroisocyanuric acid, sodium bromide, diacetoxybenzyl iodide or di(trifluoroacetoxy)benzyl iodide to the molar amount of hydrazine hydrate is (0.5-2.5):1; the mass ratio of the acid binding agent to hydrazine hydrate is (5%-10%):1; chlorine gas is continuously introduced into the reaction system, and the pressure in the reaction system is below 0.1Mpa.

8. The synthesis method according to claim 1, 6 or 7, characterized in that: in the third step, at least one of the following conditions is included: Condition 1: The reaction is carried out in the presence of an organic solvent, and the organic solvent is preferably at least one of dichloromethane, tetrahydrofuran, N,N-dimethylamide and acetonitrile; Condition 2: reaction temperature is 20°C to 35°C; Condition 3: The reaction time is 30 min to 60 min.

9. The synthesis method according to claim 1, characterized in that: It includes at least one of the following conditions: Condition 1, in the first step, after the reaction is completed, a quencher is added to terminate the reaction; Preferably, the quencher is acetic acid, and the mass ratio of acetic acid to the aminosilane of formula (II) is (0.3% to 2%): 1; Preferably, the quenching reaction temperature is 20°C to 30°C, and the quenching reaction time is 5min to 15min; Condition 2: In the second step, after the reaction, water in the reaction solution is removed; Condition 3: In the third step, after the reaction, the organic solvent is recovered by vacuum rotary evaporation, the residue is washed, filtered after washing, and the filtrate is vacuum rotary evaporated to obtain a structurally symmetrical azosilane coupling agent.

10. The synthesis method according to any one of claims 1 to 9, characterized in that: In the first step, the second step and the third step, the reaction processes are all carried out under the protection of inert gas.

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