Preparation method of 2-cyanoethyl aminopropyl trialkoxysilane

Abstract

The invention relates to a preparation method of 2-cyanoethyl aminopropyl trialkoxysilane, and belongs to the technical field of synthesis of fine chemicals. The preparation method comprises the following steps: A, adding aminopropyl trialkoxysilane into a reaction kettle, and adjusting a stable temperature under a stirring condition; b, acrylonitrile is dropwise added into the reaction kettle, the dropwise adding speed is controlled, the temperature is slowly increased, the temperature is increased to 80 DEG C after dropwise adding is completed, a heat preservation reaction is conducted, then standing is conducted, a dropwise adding reaction product is obtained, and the molar ratio of aminopropyltrialkoxysilane to acrylonitrile is 1: 1; and C, rectifying the dropwise added reaction product to obtain a finished product of the 2-cyanoethyl aminopropyl trialkoxysilane. According to the preparation method provided by the invention, under the solvent-free condition, the reaction purity is greater than 95%, and the mol mass yield is higher than 92% (on the basis of the mol mass of acrylonitrile). The process is simple, and the reaction synthesis method is high in comprehensive efficiency; the environment-friendly effect is achieved, and the corrosion to equipment is small. No solvent is used, the energy consumption is reduced, and the method can be used for industrial production.

Description

Technical Field

[0001] The invention relates to the technical field of synthesis of fine chemicals, and in particular to a method for preparing 2-cyanoethylaminopropyltrialkoxysilane. Background Art

[0002] 2-Cyanoethylaminopropyltrialkoxysilane is an important silane coupling agent, mainly used for modification of silicone resin and silicone rubber, reinforcement of glass fiber, oil-resistant sealing gaskets, surface treatment agents, waterproof coating additives in aviation, petrochemical and automotive industries, and end-capping of silicone-modified polyether resins. For example, polyether-modified resins end-capped with 2-cyanoethylaminopropylmethyldimethoxysilane have good elasticity, fast curing speed, high tear strength, good stain resistance and adhesion, and are widely recognized in the sealant industry. The introduction of polar nitrile groups in the side chains of silicone greatly improves the oil resistance and solvent resistance of the applied materials.

[0003] The conventional method for preparing 2-cyanoethylaminosilane is to esterify chlorosilane monomers (trichlorosilane, methyldichlorosilane, polydimethylsilane) with lower alcohols in a solvent, then react with expensive allylamine, and then react with acrylonitrile to synthesize cyanoethylaminosilane or cyanoethylaminosilicone oil. Since alcoholysis will produce a large amount of hydrogen chloride, if it cannot be discharged from the system in time, it is easy to cause alcoholysis to have side reactions, resulting in a decrease in product yield. The use of solvents increases the energy consumption of the product. At the same time, the strong acidity of hydrogen chloride is easy to corrode equipment, and this process has high requirements for equipment conditions. Summary of the invention

[0004] The purpose of the present invention is to provide a method for preparing 2-cyanoethylaminopropyltrialkoxysilane, which solves the technical problems of complicated technology and high cost in the existing production technology. The present invention does not use solvents, does not produce hydrogen chloride, improves product yield, and is relatively friendly to equipment.

[0005] The above-mentioned object of the present invention is achieved by the following technical solutions: A method for preparing 2-cyanoethylaminopropyltrialkoxysilane comprises the following steps: Step A, adding aminopropyltrialkoxysilane into a reaction kettle, and adjusting the stable temperature under stirring conditions; Step B, add acrylonitrile dropwise to the reaction kettle, control the dropping speed, slowly increase the temperature, raise the temperature to 80°C after the dropping is completed, keep the temperature for reaction, and then stand to obtain the dropping reaction product. The mol ratio of aminopropyltrialkoxysilane to acrylonitrile is 1:1.

[0006] Step C, distilling the dropwise reaction product to obtain a finished product of 2-cyanoethylaminopropyltrialkoxysilane.

[0007] Furthermore, in step A, the stable temperature is adjusted to 20-40°C, preferably 30-32°C.

[0008] Furthermore, in the step B, the dropwise addition time of acrylonitrile is 90 to 180 min, preferably 90 to 120 min.

[0009] Furthermore, in step B, the heat preservation reaction time is 2 hours, and then the temperature is naturally lowered and allowed to stand for 12 to 24 hours, preferably for 24 hours.

[0010] Furthermore, in step C, the vacuum degree of distillation is ≥0.098 MPa, and the fraction at 110-150°C is cut as the product, preferably the fraction at 110-140°C.

[0011] Furthermore, based on the mol mass of acrylonitrile, the mol yield of the preparation method of the present invention is higher than 92%, and the product purity is higher than 95%.

[0012] Furthermore, the reaction mechanism of the preparation method is: CH2=CH-CN2 +NH (CH2)3SiR' n (OR) 3-n →NC-CH2CH2NH(CH2)3SiR' n (OR) 3-n Wherein, R=alkyl, such as methyl, ethyl, propyl. R'=methyl. When R is equal to methyl, 2-cyanoethylaminopropyltrimethoxysilane or 2-cyanoethylaminopropylmethyldimethoxysilane is obtained. When R is equal to ethyl, 2-cyanoethylaminopropyltriethoxysilane or 2-cyanoethylaminopropylmethyldiethoxysilane is obtained. n=0 or 1 or 2 or 3.

[0013] The beneficial effects of the present invention are as follows: the preparation method provided by the present invention is to generate 2-cyanoethylaminopropyltrialkoxysilane with a purity greater than 95% and a mol mass yield greater than 92% (based on the mol mass of acrylonitrile) by reacting acrylonitrile and aminopropyltrialkoxysilane under solvent-free conditions. Compared with the cumbersome process, high cost and large amount of hydrogen chloride produced by the cyanoethylaminosilane in the prior art, the process of the present invention is simple, the reaction synthesis method is efficient, more environmentally friendly, less corrosive to the equipment, and the service life of the equipment can be extended. No solvent is used, which reduces energy consumption and thus reduces production costs, and there are few by-products, no waste is generated, and the raw material conversion rate is high, which can be used for industrial production. In the preparation method provided by the present invention, the reaction raw materials are all raw materials that are easy to obtain and relatively safe. The reaction is carried out at a temperature not higher than 100° C., and no catalyst is required, which greatly reduces production costs and has a safe process. It is highly practical. DETAILED DESCRIPTION

[0014] The technical solutions in the embodiments of the present invention are described clearly and completely below. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention. In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below in conjunction with specific embodiments.

[0015] The present invention provides a method for preparing 2-cyanoethylaminopropyltrialkoxysilane, and the reaction mechanism thereof is: CH2=CH-CN2 +NH (CH2)3SiR' n (OR) 3-n →NC-CH2CH2NH(CH2)3SiR' n (OR) 3-n Wherein, R=alkyl, such as methyl, ethyl, propyl. R'=methyl. In the case where R is equal to methyl, 2-cyanoethylaminopropyltrimethoxysilane or 2-cyanoethylaminopropylmethyldimethoxysilane is obtained. In the case where R is equal to ethyl, 2-cyanoethylaminopropyltriethoxysilane or 2-cyanoethylaminopropylmethyldiethoxysilane is obtained. n=0 or 1 or 2 or 3.

[0016] The reaction comprises the following steps: Step A: Add aminopropyltrialkoxysilane into the reaction kettle, and adjust the stable temperature under stirring conditions.

[0017] Step B, add acrylonitrile dropwise to the reaction kettle, control the dropping speed, slowly increase the temperature, and after the dropping is completed, increase the temperature to 80° C., keep the temperature for reaction, and then let it stand, the molar ratio of aminopropyltrialkoxysilane to acrylonitrile is 1:1.

[0018] Step C, distilling the dropwise reaction product to obtain a finished product of 2-cyanoethylaminopropyltrialkoxysilane.

[0019] In step A, the stabilization temperature is adjusted to 20-40°C.

[0020] In step B, the dropwise addition time of acrylonitrile is 90 to 180 minutes. The heat preservation reaction time is 2 hours, and then the temperature is naturally lowered and the mixture is allowed to stand for 12 to 24 hours to obtain a dropwise reaction product.

[0021] In step C, the vacuum degree of distillation is ≥0.098 MPa, and the fraction at 110-150°C is the product.

[0022] The finished product prepared by the method has a purity greater than 95% and a mass yield greater than 92% (based on the mol mass of acrylonitrile).

[0023] The present invention is described in detail below by means of three embodiments. Embodiment 1:

[0024] In a four-necked flask equipped with a stirrer, a constant pressure dropping funnel, a reflux condenser and a thermometer, nitrogen was introduced into the flask until the flask was full, and then 163.3 g (1 mol) of aminopropylmethyldimethoxysilane was added, stirring was started, and the temperature was adjusted to 30°C.

[0025] Weigh 53g (1mol) of acrylonitrile and put it into a dropping funnel; after the temperature stabilizes, add acrylonitrile to the four-necked bottle, controlling the speed to drip in 60 minutes. Control the reaction temperature not higher than 40℃. After the addition is completed, raise the temperature to 80℃, keep the temperature for 2 hours, and take samples for analysis.

[0026] Gas chromatography analysis showed that the content of 2-cyanoethylaminopropylmethyldimethoxysilane in the material was 89%.

[0027] After 24 hours, take samples for analysis: 2-Cyanoethylaminopropylmethyldimethoxysilane content 95%.

[0028] The reaction material was subjected to reduced pressure distillation (vacuum degree ≥ 0.098 MPa, 110-120°C fraction). 209.5 g of distilled product with a content of 96% was obtained, and the mol yield was 93%. Embodiment 2:

[0029] In a four-necked flask equipped with a stirrer, a constant pressure dropping funnel, a reflux condenser and a thermometer, nitrogen was introduced into the flask until the flask was full, and then 179.3 g (1 mol) of aminopropyltrimethoxysilane was added, stirring was started, and the temperature was adjusted to 30°C.

[0030] Weigh 53g (1mol) of acrylonitrile and put it into a dropping funnel; after the temperature stabilizes, add acrylonitrile to the four-necked bottle at a speed of 60 minutes. Control the reaction temperature to no higher than 40°C. After the addition is complete, heat it to 80°C and keep the reaction temperature for 2 hours, then take samples for analysis.

[0031] Gas chromatography analysis showed that the content of 2-cyanoethylaminopropyltrimethoxysilane in the material was 90.50%.

[0032] After 24 hours, take samples for analysis: The content of 2-cyanoethylaminopropyltrimethoxysilane is 94.5%.

[0033] The reaction material was subjected to reduced pressure distillation (vacuum degree ≥ 0.098 MPa, 110-130°C fraction). 220.3 g of distilled product with a content of 97% was obtained, and the mol yield was 92%. Embodiment 3:

[0034] In a four-necked flask equipped with a stirrer, a constant pressure dropping funnel, a reflux condenser and a thermometer, nitrogen was introduced into the flask until the flask was full, and then 221.37 g (1 mol) of aminopropyltriethoxysilane was added, stirring was started, and the temperature was adjusted to 30°C.

[0035] Weigh 53g (1mol) of acrylonitrile and put it into a dropping funnel; after the temperature stabilizes, add acrylonitrile to the four-necked bottle at a speed of 120min. Control the reaction temperature to be no higher than 40℃. After the addition is complete, raise the temperature to 80℃, keep the temperature for 2h, and take samples for analysis.

[0036] Gas chromatography analysis showed that the content of 2-cyanoethylaminopropyltriethoxysilane in the material was 91%.

[0037] After leaving it for 24 hours, sampling and analysis showed that the content of 2-cyanoethylaminopropyltriethoxysilane was 95%.

[0038] The reaction material was subjected to reduced pressure distillation (vacuum degree ≥ 0.098 MPa, 110-140°C fraction). 270.10 g of distilled product with a content of 96.5% was obtained, and the mol yield was 95%.

[0039] The present invention is not limited to the above-mentioned embodiments. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications are also considered to be within the scope of protection of the present invention. The contents not described in detail in this specification belong to the prior art known to professional and technical personnel in this field.

Claims

1. A method for preparing 2-cyanoethylaminopropyltrialkoxysilane, characterized in that: The steps include: Step A: Add aminopropyltrialkoxysilane into the reaction kettle, and adjust the stable temperature under stirring conditions; Step B: adding acrylonitrile dropwise to the reaction kettle, controlling the dropping speed, slowly raising the temperature, raising the temperature to 80° C. after the dropping is completed, keeping the temperature for reaction, and then standing to obtain a dropwise reaction product, wherein the molar ratio of aminopropyltrialkoxysilane to acrylonitrile is 1:1; Step C: distilling the dropwise reaction product to obtain a finished product of 2-cyanoethylaminopropyltrialkoxysilane.

2. The method for preparing 2-cyanoethylaminopropyltrialkoxysilane according to claim 1, characterized in that: In step A, the stabilization temperature is adjusted to 20-40°C.

3. The method for preparing 2-cyanoethylaminopropyltrialkoxysilane according to claim 1, characterized in that: In step B, the dropwise addition time of acrylonitrile is 90 to 180 minutes.

4. The method for preparing 2-cyanoethylaminopropyltrialkoxysilane according to claim 1, characterized in that: In step B, the reaction time is 2 hours, and then the temperature is naturally lowered and allowed to stand for 12 to 24 hours.

5. The method for preparing 2-cyanoethylaminopropyltrialkoxysilane according to claim 1, characterized in that: In step C, the vacuum degree of distillation is ≥0.098 MPa, and the fraction at 110-150° C. is taken as the product.

6. The method for preparing 2-cyanoethylaminopropyltrialkoxysilane according to claim 1, characterized in that: The reaction mechanism of the preparation method is: CH2=CH-CN2 +NH (CH2)3SiR’ n (OR) 3-n →NC-CH2CH2NH(CH2)3SiR’ n (OR) 3-n Wherein, R=alkyl, including methyl, ethyl or propyl; R'=methyl; in the case of R=methyl, 2-cyanoethylaminopropyltrimethoxysilane or 2-cyanoethylaminopropylmethyldimethoxysilane is obtained; in the case of R=ethyl, 2-cyanoethylaminopropyltriethoxysilane or 2-cyanoethylaminopropylmethyldiethoxysilane is obtained; n=0 or 1 or 2 or 3.