Method for jointly preparing silazacyclopentane silane and alkoxy trialkylsilane

Abstract

The invention discloses a method for jointly preparing silazacyclopentane silane and alkoxy trialkylsilane, which comprises the following steps of: firstly, promoting intramolecular coupling of amino silane by adding a main catalyst and an auxiliary catalyst so as to reduce the reaction temperature and time; amino alkoxy silane and excessive hexaalkyldisilazane are used as raw materials, a trialkylsilyl substituted unstable intermediate structure is formed through deamination, then cyclization reaction is carried out, alkoxy trialkylsilane fraction and silazacyclopentyl silane distillate are obtained in sequence, energy consumption is remarkably reduced, the process difficulty is reduced, and the yield is increased. The problem that the conventional amino silane easily causes difficult product storage or inactivation is solved, the problems that silazacyclopentyl silane is high in preparation difficulty and difficult to separate are solved, and the obtained alkoxy trialkylsilane can obtain economic benefits after being purified and distributed.

Description

Technical Field

[0001] The invention relates to the technical field of silane preparation, and in particular to a method for jointly preparing silaazacyclopentane silane and alkoxytrialkylsilane. Background Art

[0002] As an important organosilicon product that has developed rapidly in recent years, aminosilane coupling agent usually contains two parts, amino and silane, in its structure, and can bridge organic and inorganic substrates through these two groups, thereby improving the compatibility and bonding strength of the two. The international research on aminosilane was first initiated by companies such as Union Carbide (UC) and Dow Corning in the United States. In the mid-20th century, a series of aminosilanes with typical structures were developed, which were mainly used to improve glass fiber to enhance the mechanical properties of plastic products. In recent years, with the development of materials science, the application scope of aminosilane coupling agent has gradually expanded to many other fields such as rubber technology, coatings, adhesives and sealants, processing of various fillers, and acting as drug carriers. It can not only improve the mechanical properties of materials, but also improve weather resistance and corrosion resistance to a certain extent, greatly improving the performance of materials.

[0003] Due to the high activity of amino groups, aminosilane coupling agents are prone to reaction priority conflicts with the application system during use, which leads to difficulties in product storage and premature inactivation, or the need to prepare in a two-component form and then mix them when used, increasing the cost and complexity of use. In addition, the high boiling point of aminosilane and the pressure reaction requirements in certain processes cause the high temperature and pressure conditions during the purification process to cause some aminosilanes to dealcoholize and cyclize to form silazacyclopentylsilane, which not only increases VOC emissions but also reduces product purity. Through research, it is found that this silazacyclopentylsilane can prevent the amino group from reacting with the application system by ringing it, and can open the ring under conditions such as water or alcohol to restore the original amino group to play its due role. However, the current synthesis schemes for silazacyclopentylsilane all use chloropropyltrialkoxysilane and various ammonia substances to continuously keep warm at high temperature for amination reaction. The reaction selectivity is not high, the side reactions are too many, the yield is poor, and the cost is quite high. These factors limit the market application and industrial demand of silazacyclopentylsilane.

[0004] Chinese patent document CN109824714A reports a method for preparing silazacyclopentylsilane. The method adds transition metals such as sodium ethoxide and nickel powder at 65-80°C to promote and catalyze the intramolecular dealcoholization reaction of 3-aminopropyltriethoxysilane, and then distills it under negative pressure and -20°C brine condensation to obtain the desired product. The by-product ethanol produced during the production process of this method cannot be discharged in time at the reaction temperature, and continues to react with the product in the system to form aminopropyltriethoxysilane and polysiloxane structure, which increases the difficulty of purification, reduces the yield, and has too high equipment process requirements and energy consumption, which is not conducive to industrial production.

[0005] Chinese patent document CN112430245A reports a method for preparing a similar silane coupling agent, the difference being that an additional n-butyl group is substituted on the N in its structure. The method is to pass an alcohol solution of aminosilane and an organotin catalyst into a continuous reactor at a certain flow rate for a programmed temperature reaction, and then pass through a distillation tower and a receiver to collect the final product at a yield of 79%. Although the method is simple to synthesize, it requires multiple reactors and condensers, which is costly and complex in wiring, and is not conducive to industrial production. In addition, the catalyst in the process route uses a non-environmentally friendly tin catalyst, which is harmful to the environment and human body and has limited application environment.

[0006] International patent document WO2003091186A2 reports the synthesis of silazacyclopentylsilane by using ammonium chloride as a catalyst, but the yield is only 8% and the application value is very low.

[0007] Kirilin, Belova and Korobova (2009) "Use of 3-(Ethoxysilyl)-1-propylamine in the Synthesis of Silicon Heterocycles" reported a method for synthesizing silanyl azacyclopentylsilane, using excess hexamethyldisilazane and aminopropyltriethoxysilane as raw materials. First, ammonia was removed to replace a trimethylsilyl group on the amino group of aminopropyltriethoxysilane, and then the ethoxytrimethylsilane was removed and cyclized with the highly active secondary amine in the silane structure by continuous heat preservation. Although the by-products produced in the reaction scheme can also be purified and sold as commodities for profit, its synthesis requires heating to above 200°C and heat preservation for 1 to 2 days. The actual production is very time-consuming and energy-intensive, which greatly reduces the production efficiency. Summary of the invention

[0008] The present invention aims to provide a method for the combined preparation of silazacyclopentane silane and alkoxytrialkylsilane, so as to at least solve one of the many defects of the above prior art.

[0009] In view of this, the scheme of the present invention is:

[0010] A method for jointly preparing silaazacyclopentane silane and alkoxytrialkylsilane, comprising the steps of:

[0011] a) adding aminosilane and hexaalkyldisilazane into a reactor in proportion, adding a main catalyst and a co-catalyst, stirring and reacting at 120-150° C. for 3-4 hours, removing ammonia gas, until the material forms a light yellow viscous liquid to obtain an intermediate material;

[0012] b) cooling the intermediate material to 100-130° C., keeping the temperature for 5-10 hours and collecting the fractions to obtain alkoxytrialkylsilane;

[0013] c) distilling the remaining material to obtain silaazacyclopentylsilane.

[0014] Furthermore, the molar ratio of the aminosilane to the hexaalkyldisilazane is 1:(0.7-1.1).

[0015] Furthermore, the aminosilane is selected from at least one of aminopropyltrimethoxysilane and aminopropyltriethoxysilane; and / or the hexaalkyldisilazane is at least one of hexamethyldisilazane, hexaethyldisilazane and bis(triisopropylsilyl)amine.

[0016] Furthermore, the main catalyst is cuprous halide, and the co-catalyst is organic bismuth and / or ammonium alkaline catalyst.

[0017] Preferably, the amount of the main catalyst added is 0.3-0.7% of the mass of the aminosilane; and / or the amount of the co-catalyst added is 0.1-0.3% of the mass of the aminosilane.

[0018] Preferably, the cuprous halide is selected from at least one of cuprous iodide and cuprous chloride.

[0019] Preferably, the organic bismuth is selected from at least one of bismuth octanoate, bismuth isooctanoate and bismuth methanesulfonate.

[0020] Preferably, the ammonium alkaline catalyst is selected from at least one of ammonium sulfate and ammonium chloride.

[0021] Furthermore, in step a), the reactor is purged with an inert gas before adding materials.

[0022] Furthermore, in step c), the distillation process is reduced pressure distillation.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The combined preparation method of the present invention first promotes the intramolecular coupling of aminosilane by adding a main catalyst and a co-catalyst to reduce the reaction temperature and time; aminoalkoxysilane and excess hexaalkyldisilazane are used as raw materials, and an unstable intermediate structure substituted with a trialkylsilyl group is formed by deamination, and then a cyclization reaction occurs to obtain an alkoxytrialkylsilane fraction and a silazacyclopentylsilane distillate in sequence, which significantly reduces energy consumption and process difficulty, and solves the problem that conventional aminosilane easily leads to product storage difficulties or inactivation, and the problem that silazacyclopentylsilane is difficult to prepare and difficult to separate, and the obtained alkoxytrialkylsilane can also be purified and distributed to obtain economic benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the hydrogen nuclear magnetic spectrum of 1-aza-2-sila-2,2-diethoxycyclopentane prepared by the present invention.

[0026] Figure 2 This is the infrared spectrum of 1-aza-2-sila-2,2-diethoxycyclopentane prepared by the present invention. DETAILED DESCRIPTION

[0027] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0028] In one embodiment, a method for jointly preparing silazacyclopentane silane and alkoxytrialkylsilane is provided, the steps comprising:

[0029] S1. Purge with nitrogen to ensure that the reaction vessel is dry, add aminosilane and hexaalkyldisilazane to the reactor in proportion, add the main and co-catalysts, stir the reaction at 120 to 150 ° C for 3 to 4 hours, remove ammonia, until the material forms a light yellow viscous liquid to obtain an intermediate material;

[0030] S2. The intermediate material is cooled to 100-130°C, kept warm for 5-10 hours and the fractions are collected to obtain alkoxytrialkylsilane;

[0031] S3. The remaining material is subjected to reduced pressure distillation to obtain silaazacyclopentylsilane.

[0032] The reaction route of the above process is:

[0033]

[0034] Among them, R 1is methoxy or ethoxy; R 2 It is methyl, ethyl or isopropyl.

[0035] In a preferred embodiment, the aminosilane is selected from at least one of aminopropyltrimethoxysilane and aminopropyltriethoxysilane; and / or the hexaalkyldisilazane is at least one of hexamethyldisilazane, hexaethyldisilazane and bis(triisopropylsilyl)amine. The molar ratio of the aminosilane to the hexaalkyldisilazane is 1:(0.7-1.1).

[0036] In a preferred embodiment, the main catalyst is cuprous halide, and the co-catalyst is organic bismuth and / or ammonium alkaline catalyst. Preferably, the cuprous halide is selected from at least one of cuprous iodide and cuprous chloride; preferably, the organic bismuth is selected from at least one of bismuth octanoate, bismuth isooctanoate, and bismuth methanesulfonate; preferably, the ammonium alkaline catalyst is selected from at least one of ammonium sulfate and ammonium chloride.

[0037] In a preferred embodiment, the amount of the main catalyst added is 0.3-0.7% of the mass of the aminosilane; and / or the amount of the co-catalyst added is 0.1-0.3% of the mass of the aminosilane.

[0038] In the above embodiment, the preparation method is to deaminize aminosilane with hexaalkyldisilazane under the action of cuprous halide and bismuth-based or alkaline ammonia combined catalyst to form an unstable intermediate structure substituted with trialkylsilyl. The secondary amine in this structure has strong alkalinity and can easily undergo intramolecular coupling reaction with silanoxy under the action of transition metal catalyst, remove alkoxytrialkylsilane, form a silanyl-nitrogen heterocyclic structure, and obtain two products after separation and purification.

[0039] In the above embodiment, this silazacyclopentylsilane solves the problem that conventional aminosilanes are prone to causing product storage difficulties or inactivation. As a new type of silane coupling agent, it solves the problems existing in existing aminosilanes and has potential application advantages. In addition, this solution can simultaneously prepare high-purity alkoxytrialkylsilanes, solving the problem of difficult preparation and separation of silazacyclopentylsilanes. The byproduct ammonia can be adsorbed by industrial means for other industrial purposes, generating additional economic benefits. At the same time, the method has a simple process and mild reaction conditions. The combined preparation of two products can further reduce costs and has broad application prospects.

[0040] In the above embodiment, the prepared 1-aza-2-sila-2,2-diethoxycyclopentane has a hydrogen NMR spectrum as shown in Figure 1 As shown, it can be obtained from 1H NMR shows that the peaks at δ = 2.66, 1.48, and 0.59 ppm belong to the three methylene groups on silicon and nitrogen. Unlike KH550, the peak of -NH- in cyclosilazane shifts from 1.36 ppm to 0.99, and the area is halved, which corresponds to the peak of -NH 2 The change from -NH- to -NH- proves that 1-aza-2-silanyl-2,2-diethoxycyclopentane was successfully synthesized. Figure 2 As shown in the FT IR spectrum, the chemical shift is 3369 cm -1 The peak at 3300cm is the characteristic absorption peak of secondary ammonia, while KH550 will be at 3300cm -1 An additional characteristic peak of primary amine appeared at the position of the cyclopentane, proving the successful synthesis of 1-aza-2-sila-2,2-diethoxycyclopentane.

[0041] The following are preferred implementation examples. If the manufacturer of the reagent or instrument is not specified in the examples, conventional products can be purchased from the market. If the specific conditions are not specified, conventional conditions or conditions recommended by the manufacturer can be followed.

[0042] Example 1

[0043] Into a dry 500ml three-necked flask filled with nitrogen, 110.7g (0.5mol) of aminopropyltriethoxysilane, 64.6g (0.4mol) of hexamethyldisilazane, 0.5g of cuprous iodide and 0.2g of ammonium sulfate were added, and the mixture was kept at 120°C for 3h to remove ammonia to obtain a trimethylsilyl-substituted intermediate. The generated ammonia can be used for other industrial purposes after absorption; the system temperature was lowered to 100°C and kept for reaction for 6h, and 46.7g (0.395mol, yield 79%) of ethoxytrimethylsilane was collected in a condensation collection bottle; after replacing the collection bottle, the crude silane in the flask was subjected to reduced pressure distillation at a pressure of 3mmHg, and 71.2g (0.406mol, yield 81.2%) of 1-aza-2-sila-2,2-diethoxycyclopentane was collected at 87-95°C.

[0044] Example 2

[0045] Into a dry 500ml three-necked flask filled with nitrogen, 110.7g (0.5mol) of aminopropyltriethoxysilane, 80.7g (0.5mol) of hexamethyldisilazane, 0.4g of cuprous chloride and 0.3g of ammonium chloride were added, and the mixture was kept at 145°C for 4h to remove ammonia to obtain a trimethylsilyl-substituted intermediate. The generated ammonia can be used for other industrial purposes after absorption; the system temperature was lowered to 120°C and kept for reaction for 8h, and 43.5g (0.368mol, yield 73.6%) of ethoxytrimethylsilane was collected in a condensation collection bottle; after replacing the collection bottle, the crude silane in the flask was subjected to reduced pressure distillation at a pressure of 3mmHg, and 67.4g (0.406mol, yield 76.9%) of 1-aza-2-sila-2,2-diethoxycyclopentane was collected at 87-95°C.

[0046] Example 3

[0047] Into a dry 500ml three-necked flask filled with nitrogen, 110.7g (0.5mol) of aminopropyltriethoxysilane, 122.8g (0.5mol) of hexaethyldisilazane, 0.5g of cuprous iodide, and 0.2g of bismuth neodecanoate were added, and the mixture was kept at 130°C for 3h to remove ammonia to obtain a triethylsilyl-substituted intermediate. The generated ammonia can be used for other industrial purposes after absorption; the system temperature was lowered to 110°C and kept for reaction for 8h, and 61g (0.38mol, yield 76.1%) of ethoxytriethylsilane was collected in a condensation collection bottle; after replacing the collection bottle, the crude silane in the flask was subjected to reduced pressure distillation at a pressure of 3mmHg, and 69.5g (0.396mol, yield 79.3%) of 1-aza-2-sila-2,2-diethoxycyclopentane was collected at 87-95°C.

[0048] Comparative Example 1

[0049] In a dry 500ml three-necked flask filled with nitrogen, 221.4g (1mol) of aminopropyltriethoxysilane and 2.2g (mass ratio 1%) of ammonium sulfate were added, and the mixture was reacted at 180°C for 15h. The reaction apparatus was changed to a distillation apparatus, and the product was subjected to reduced pressure distillation at a pressure of 3mmHg. 33g (0.188mol, yield 18.8%) of 1-aza-2-sila-2,2-diethoxycyclopentane was collected at 87-95°C.

[0050] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for jointly preparing silazacyclopentane silane and alkoxytrialkylsilane, characterized in that the steps include: a) adding aminosilane and hexaalkyldisilazane into a reactor in proportion, adding a main catalyst and a co-catalyst, stirring and reacting at 120-150° C. for 3-4 hours, removing ammonia gas, until the material forms a light yellow viscous liquid to obtain an intermediate material; b) cooling the intermediate material to 100-130° C., keeping the temperature for 5-10 hours and collecting the fractions to obtain alkoxytrialkylsilane; c) distilling the remaining material to obtain silaazacyclopentylsilane; The reaction route of the above process is: Wherein, R1 is methoxy or ethoxy; R2 is methyl, ethyl or isopropyl.

2. The method according to claim 1, characterized in that The molar ratio of the aminosilane to the hexaalkyldisilazane is 1:(0.7-1.1).

3. The method according to claim 1, characterized in that The aminosilane is selected from at least one of aminopropyltrimethoxysilane and aminopropyltriethoxysilane; and / or the hexaalkyldisilazane is at least one of hexamethyldisilazane, hexaethyldisilazane and bis(triisopropylsilyl)amine.

4. The method according to claim 1, characterized in that The main catalyst is cuprous halide, and the co-catalyst is organic bismuth and / or ammonium alkaline catalyst.

5. The method according to claim 4, characterized in that The amount of the main catalyst added is 0.3-0.7% of the mass of the aminosilane; and / or the amount of the co-catalyst added is 0.1-0.3% of the mass of the aminosilane.

6. The method according to claim 4, characterized in that The cuprous halide is selected from at least one of cuprous iodide and cuprous chloride.

7. The method according to claim 4, characterized in that The organic bismuth is selected from at least one of bismuth octanoate, bismuth isooctanoate and bismuth methanesulfonate.

8. The method according to claim 4, characterized in that The ammonium alkaline catalyst is selected from at least one of ammonium sulfate and ammonium chloride.

9. The method according to claim 1, characterized in that: In step a), the reactor is purged with an inert gas before adding materials.

10. The method according to claim 1, characterized in that In step c), the distillation process is reduced pressure distillation.

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