Method for synthesizing 2-methyl-3-mercaptopropyl alkoxy silane through thiourea method

Abstract

The invention relates to the technical field of compound synthesis, in particular to a method for synthesizing 2-methyl-3-mercaptopropyl alkoxy silane by a thiourea method, which comprises the following steps: adding 2-methyl-3-chloropropyl alkoxy silane, thiourea, a solvent, a catalyst and a stabilizer into a reaction kettle, heating to 60-120 DEG C, and reacting for 12-72 hours to generate amidino salt; adding a certain amount of alkali at 30-100 DEG C, and keeping the temperature for 1-6 hours to obtain a crude product; and adding the crude product into a rectifying tower for rectification at the rectification pressure of 0-0.1 MP and the rectification temperature of 30-190 DEG C, reducing the pressure to 0-0.08 MP, recovering the solvent, and rectifying to obtain the 2-methyl-3-mercaptopropyl alkoxy silane. The mercaptopropyl functional group (-SH) synthesized by the method has high activity, the synthesis method is simple in process, short in synthesis time, high in synthesis efficiency and high in yield of finished products, and industrial mass production is facilitated.

Description

Technical Field

[0001] The invention relates to the technical field of compound synthesis, in particular to a method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by a thiourea method. Background Art

[0002] 2-Methyl-3-mercaptopropyl alkoxysilane is a multifunctional sulfur-containing silane coupling agent with reactivity and crosslinkability. Its highly active mercaptopropyl functional group (-SH) can react with olefins, unsaturated lipids, polyesters, and metals. At the same time, the alkoxy functional group is hydrolyzed to generate silanols that can react with inorganic substances, etc., and firmly bond organic polymers and inorganic fillers together. In the prior art, there is no report on the synthesis of 2-methyl-3-mercaptopropyl alkoxysilane due to the high activity of the mercapto group in the prior art, but there are a large number of reports on the synthesis of 3-mercaptopropyl alkoxysilane. In the prior art, the preparation methods of 3-mercaptopropyl trimethoxysilane include thiourea method, sodium hydrosulfide, hydrogen sulfide method, etc.

[0003] For example, in patent CN105153216A, aqueous sodium sulfide is dissolved in methanol, and then silicon tetrachloride is added for reaction. After the reaction is completed, tetramethoxysilane is added to completely consume the excess water, and then chloropropyltrimethoxysilane is added to the reaction vessel for reaction to obtain 3-mercaptopropyltrimethoxysilane. The main disadvantage is that a large amount of silicon dioxide and sodium chloride salt will be produced, and the overall utilization rate of sodium hydrosulfide is low. Patent CN1401650 uses γ-chloropropyltrimethoxysilane and thiourea as raw materials, anhydrous methanol as solvent, and potassium iodide as a promoter. After reflux reaction, ethylenediamine is used for alkalization to obtain γ-mercaptopropyltrimethoxysilane. The disadvantage is that the activity of the mercapto functional group is too high when synthesizing this product, and the product yield is too low. Patent CN102659831 mainly uses sodium hydrosulfide, chloropropyltrimethoxysilane and water to react under the action of a buffer to generate mercaptopropyltrimethoxysilane. The main disadvantage is that there is water in the reaction system, and the product mercaptopropyltrimethoxysilane is easily hydrolyzed. The hydrogen sulfide method is to react hydrogen sulfide with sodium methoxide to obtain a methanol solution of sodium hydrosulfide, and then react with chloropropyltrimethoxysilane under a high pressure system to obtain mercaptopropyltrimethoxysilane. The main disadvantage is that the raw material hydrogen sulfide is highly toxic, and the high pressure of the reaction system has safety and environmental protection problems. The disadvantages of the prior art are difficulty in filtering, generation of toxic gases, and low product yield. Summary of the invention

[0004] The object of the present invention is to provide a method for preparing 2-methyl-3-mercaptopropyl alkoxysilane, which has mild reaction conditions, is easy to operate, has a short reaction time, a large safety factor, has low requirements on equipment, and has a high product yield and high content.

[0005] The present invention provides a method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method, comprising the following steps:

[0006] S1: Add 2-methyl-3-chloropropyl alkoxysilane, thiourea, solvent, catalyst and stabilizer into a reaction kettle, raise the temperature to 60-120°C, react for 12-72h, and react to generate amidine salt;

[0007] S2: adding a certain amount of alkali at 30-100°C and keeping warm for 1-6h to obtain a crude product;

[0008] S3: adding the crude product into a distillation tower for distillation, the distillation pressure is 0-0.1MP, the distillation temperature is 30-190°C, the pressure is reduced to 0-0.08MP and the solvent is recovered, and 2-methyl-3-mercaptopropylalkoxysilane is obtained by distillation.

[0009] Preferably, the 2-methyl-3-chloropropyl alkoxysilane includes: 2-methyl-3-chloropropyltrimethoxysilane, 2-methyl-3-chloropropyltriethoxysilane, 2-methyl-3-chloropropylmethyldimethoxysilane, 2-methyl-3-chloropropylmethyldiethoxysilane, 2-methyl-3-chloropropyldimethylmethoxysilane, and 2-methyl-3-chloropropylmethylethoxysilane.

[0010] Preferably, the solvent includes: methanol, ethanol, petroleum ether, dimethylformamide, dimethylacetamide, toluene, and xylene.

[0011] Preferably, the catalyst includes: 18 crown 6, 15 crown 5, cyclodextrin, benzyltriethylammonium chloride (TEBA), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and potassium iodide.

[0012] Preferably, the stabilizer includes: butylated hydroxyanisole (BHA), di-tert-butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ).

[0013] Preferably, the base includes: ammonia, ethylamine, triethylamine, diethylamine, ethylenediamine.

[0014] Preferably, the ratio of the 2-methyl-3-chloropropyl alkoxysilane, the catalyst and the stabilizer is 1:0.1%-5%:0.1%-5%.

[0015] Preferably, the mass ratio of the solvent to the 2-methyl-3-chloropropylalkoxysilane is 0.1-3:1.

[0016] Preferably, during synthesis, the molar ratio of the 2-methyl-3-chloropropylalkoxysilane, thiourea and base is 1:1-1.5:0.5-1.

[0017] The structural formula of the product is HSCH2CH(CH3)CH2Si(CH3)m(OR)3-m, wherein m is 0 to 2; and R is CH3 or CH2CH3.

[0018] The chemical reaction equation of the present invention is:

[0019] ClCH2CH(CH3)CH2Si(CH3)m(OR)3-m+NH2C(S)NH2+NH3→ClCH2CH(CH3)CH2Si(CH3)m(OR)3-m+NH2C(NH)NH2﹒ HCl; wherein m is 0-2; R is CH3 or CH2CH3.

[0020] The beneficial effects of the present invention are as follows: the present invention utilizes thiourea and 2-methyl-3-mercaptopropyl alkoxysilane to react in an organic solvent, and then adds a base to obtain 2-methyl-3-mercaptopropyl alkoxysilane. The synthesized 2-methyl-3-mercaptopropyl alkoxysilane has a high activity due to the presence of methyl groups, and its mercaptopropyl functional group (-SH) can react with olefins, unsaturated fats, polyesters, and metals. In particular, the alkoxy functional group is hydrolyzed to generate silanols, which can react with inorganic substances and the like, and firmly bond the organic polymer to the inorganic filler. The special function for metals makes it easy to connect metals and other inorganic fillers. The synthesis method of this product has a simple process, a short synthesis time, a high synthesis efficiency, and a high yield of the finished product, which is conducive to industrial mass production. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 Schematic diagram of the synthesis of 2-methyl-3-mercaptopropyltrimethoxysilane;

[0022] Figure 2 Schematic diagram of the synthesis of 2-methyl-3-mercaptopropyltriethoxysilane;

[0023] Figure 3 Schematic diagram of the synthesis of 2-methyl-3-mercaptopropylmethyldimethoxysilane. DETAILED DESCRIPTION

[0024] The present invention will be further described below in conjunction with specific embodiments.

[0025] Example 1

[0026] The present invention provides a method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method, specifically a method for synthesizing 2-methyl-3-mercaptopropyl trimethoxysilane, comprising the following steps:

[0027] Add 25g petroleum ether, 42.5g 2-methyl-3-chloropropyltrimethoxysilane (0.2mol), 16.7g thiourea (0.22mol), 0.2g potassium iodide, and 0.2g di-tert-butylhydroxytoluene into the kettle, stir and react at 90-110℃ for 72 hours, then cool to 60℃, pass 3.4g ammonia (0.2mol), and keep warm for 2h. After the reaction, cool the reaction solution to room temperature, filter, remove the solvent in the filtrate under reduced pressure, and then distill to obtain 38.07g of the product 2-methyl-3-mercaptopropyltrimethoxysilane.

[0028] This synthetic reaction refers to Figure 1 The synthesis method has a simple process, a short synthesis time, a yield of 91.4%, and a purity of 98.2%, which is conducive to industrial mass production.

[0029] Example 2

[0030] The present invention provides a method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by a thiourea method, specifically a method for synthesizing 2-methyl-3-mercaptopropyl triethoxysilane, comprising the following steps:

[0031] Add 35g ethanol, 63.7g 2-methyl-3-chloropropyltriethoxysilane (0.25mol), 22.8g thiourea (0.3mol), 0.3g potassium iodide, and 0.3g di-tert-butylhydroxytoluene into the kettle, stir and react at 90-110℃ for 72 hours, cool to 60℃, add 9.7g (0.16mol) of ethylenediamine dropwise, and keep warm for 2h. After the reaction is completed, go directly to the distillation kettle, remove the solvent in the filtrate under reduced pressure, and then distill to obtain 57.06g of the product 2-methyl-3-mercaptopropyltriethoxysilane.

[0032] This synthetic reaction refers to Figure 2 Compared with traditional processes, this synthetic reaction has a high safety factor, low equipment requirements, a yield of 90.5%, and a purity of up to 98.6%, and has a high development prospect.

[0033] Example 3

[0034] The present invention provides a method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by a thiourea method, specifically a method for synthesizing 2-methyl-3-mercaptopropyl methyldimethoxysilane, comprising the following steps:

[0035] Add 25g toluene, 39.34g 2-methyl-3-chloropropylmethyldimethoxysilane (0.2mol), 17.5g thiourea (0.23mol), 0.2g tetrabutylammonium bromide, and 0.2g di-tert-butylhydroxytoluene into the kettle, stir and react at 90-110℃ for 72 hours, then cool to 60℃, pass 3.4g ammonia (0.2mol), and keep warm for 2h. After the reaction, cool the reaction solution to room temperature, filter, remove the solvent in the filtrate under reduced pressure, and then distill to obtain 26.5g of the product 2-methyl-3-mercaptopropylmethyldimethoxysilane.

[0036] Please refer to this synthesis reaction Figure 2 The reaction conditions are mild and easy to operate, with a yield of 68.2% and a purity of 98.1%.

[0037] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method, characterized in that: The steps include: S1: Add 2-methyl-3-chloropropyl alkoxysilane, thiourea, solvent, catalyst and stabilizer into a reaction kettle, raise the temperature to 60-120°C, react for 12-72h, and react to generate amidine salt; S2: adding a certain amount of alkali at 30-100°C and keeping warm for 1-6h to obtain a crude product; S3: adding the crude product into a distillation tower for distillation, the distillation pressure is 0-0.1MP, the distillation temperature is 30-190°C, the pressure is reduced to 0-0.08MP and the solvent is recovered, and 2-methyl-3-mercaptopropylalkoxysilane is obtained by distillation.

2. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The 2-methyl-3-chloropropyl alkoxysilane includes: 2-methyl-3-chloropropyl trimethoxysilane, 2-methyl-3-chloropropyl triethoxysilane, 2-methyl-3-chloropropyl methyl dimethoxysilane, 2-methyl-3-chloropropyl methyl diethoxysilane, 2-methyl-3-chloropropyl dimethyl methoxysilane, and 2-methyl-3-chloropropyl methyl ethoxysilane.

3. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The solvent includes: methanol, ethanol, petroleum ether, dimethylformamide, dimethylacetamide, toluene, and xylene.

4. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The catalyst includes: 18 crown 6, 15 crown 5, cyclodextrin, benzyltriethylammonium chloride (TEBA), tetrabutylammonium bromide (TBAB), tetrabutylammonium chloride, tetrabutylammonium hydrogen sulfate, trioctylmethylammonium chloride, dodecyltrimethylammonium chloride, tetradecyltrimethylammonium chloride, and potassium iodide.

5. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The stabilizer includes: butylated hydroxyanisole (BHA), di-tert-butylated hydroxytoluene (BHT), and tert-butylhydroquinone (TBHQ).

6. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The base includes: ammonia, ethylamine, triethylamine, diethylamine, ethylenediamine.

7. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The ratio of the 2-methyl-3-chloropropyl alkoxysilane, the catalyst and the stabilizer is 1: 0.1%-5%: 0.1%-5%.

8. The method for synthesizing 2-methyl-3-mercaptopropyl alkoxysilane by thiourea method according to claim 1, characterized in that: The mass ratio of the solvent to the 2-methyl-3-chloropropylalkoxysilane is 0.1-3:

1.

9. The method for synthesizing 2-methyl-3-mercaptopropylalkoxysilane by thiourea method according to claim 1, characterized in that: During the synthesis, the molar ratio of the 2-methyl-3-chloropropyl alkoxysilane, thiourea and base is 1:1-1.5:0.5-1.

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