Preparation method of thiocarboxylate silane

Abstract

The invention provides a preparation method of thiocarboxylate silane. The preparation method comprises the following steps: (1) mixing sulfide, ionic liquid, a phase transfer catalyst and acyl chloride for reaction; and (2) adding chloropropyltriethoxysilane and a condensation inhibitor into the reaction system in the step (1), and reacting to obtain thiocarboxylate silane. The ionic liquid is used as the solvent, and the condensation inhibitor is added, so that the method has the advantages of short reaction period, high product yield, high purity, no generation of high-salinity wastewater, safety and environmental protection.

Description

Technical Field

[0001] The invention relates to a method for preparing thiocarboxylate silane, and belongs to the technical field of silane coupling agents. Background Art

[0002] Sulfur-containing silane coupling agents are widely used in the field of rubber modification, and the demand and production volume are increasing year by year. Among them, thiocarboxylate silane, as a new type of silane coupling agent product, has a special chemical structure and stronger high temperature resistance. According to the reaction system, the main synthesis methods of thiocarboxylate silane can be divided into two types: solvent-free method and solvent method.

[0003] Patent CN 103709189A directly reacts mercaptopropyl silane with acyl chloride in the absence of solvent to generate thiocarboxylate silane. This method is a non-aqueous system and can inhibit the hydrolysis of raw materials and products, but the disadvantage is that a large amount of hydrogen chloride gas will be generated during the reaction, which needs to be extracted and treated under negative pressure in time; the remaining hydrogen chloride in the product will also affect the purity of the product, which needs to be further purified and increases the cost. The mercaptopropyl silane in the raw material is also a silane coupling agent, which is relatively expensive and is not suitable for large-scale production.

[0004] Patent CN 103193816B takes sulfide as the starting point in the aqueous phase, and under the action of a phase transfer catalyst, first reacts with acyl chloride to generate thiocarboxylate, and then reacts with 3-chloropropyltriethoxysilane at 60-90°C for 6-15h to synthesize thiocarboxylate silane. During the reaction, substances such as silanol protective agents are also added to prevent the production of hydrogen sulfide and inhibit the hydrolysis of alkoxy groups. This method solves the problem of the generation of hydrogen chloride gas, but there are problems such as too complicated steps, long reaction time, and low production efficiency. In a reaction system with water as a solvent, side reactions will inevitably occur, generating hydrogen sulfide and high-salt organic wastewater, increasing the cost of three waste treatment; and in the aqueous phase, acyl chloride hydrolysis is serious, 3-chloropropyltriethoxysilane and the product will also be hydrolyzed, resulting in a low product yield; in addition, the higher the water content of the product, the worse the stability, which is not conducive to preservation.

[0005] Patent CN 110003266B also synthesizes thiocarboxylate silane by reacting thiocarboxylate with 3-chloropropyltriethoxysilane at 60-90°C. The difference is that the reaction system is in oil-water phase, and the preferred reaction time is 4-6h. The addition of organic solvents (aliphatic hydrocarbons, aromatic hydrocarbons, halogenated hydrocarbons, ethers, alcohols) helps to reduce the water content in the oil phase after phase separation, thereby inhibiting product hydrolysis and improving yield and stability. However, the reaction will still produce a large amount of high-salt organic wastewater, increasing the cost of three waste treatment; the use of organic solvents also increases safety risks.

[0006] Therefore, it is urgent to design a method for preparing thiocarboxylate silane with shorter reaction cycle, lower cost, safety and environmental protection under the premise of ensuring product yield, so as to solve the above problems. Summary of the invention

[0007] In view of the above problems existing in the prior art, the object of the present invention is to provide a method for preparing thiocarboxylate silane by using a non-aqueous phase. The method of the present invention has the advantages that by using an ionic liquid as a solvent and adding a condensation inhibitor, the system temperature can be increased, the hydrolysis side reaction can be inhibited, and the reaction cycle can be reduced; at the same time, the product purity and yield are improved, high-salt wastewater is not generated, and the system is safe and environmentally friendly.

[0008] In order to achieve the above invention object, the technical solution of the present invention is as follows:

[0009] The present invention provides a method for preparing thiocarboxylate silane, comprising the following steps:

[0010] (1) mixing a sulfide, an ionic liquid, a phase transfer catalyst and an acyl chloride to react;

[0011] (2) Adding chloropropyltriethoxysilane and a condensation inhibitor to the reaction system of step (1) to react to obtain thiocarboxylate silane.

[0012] In the method of the present invention, the following reaction occurs in step (1):

[0013]

[0014] In the formula, R1 is a straight chain or branched chain alkyl group (C≥3);

[0015] The step (2) undergoes the following reaction:

[0016]

[0017] In one embodiment, the sulfide is selected from one or more of sodium sulfide and sodium hydrosulfide, preferably anhydrous sodium sulfide.

[0018] In one embodiment, the ionic liquid is selected from imidazolium ionic liquids, preferably one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bromide, and 1-hexyl-3-methylimidazolium chloride.

[0019] In one embodiment, the phase transfer catalyst is selected from quaternary ammonium salt compounds, preferably one or more of tetrabutylammonium bromide, tetrapropylammonium chloride, tetrapropylammonium bromide and the like.

[0020] In one embodiment, the acyl chloride is selected from alkyl acyl chlorides, wherein the alkyl group is preferably a linear or branched alkyl group with C≥3, preferably one or more of isobutyryl chloride, hexanoyl chloride, and octanoyl chloride.

[0021] In one embodiment, the condensation inhibitor is selected from chlorosilane compounds and acyl chloride compounds, preferably one or more of tert-butyldimethylchlorosilane, tert-butyldiphenylchlorosilane, triisopropylchlorosilane, 9-fluorenylmethylcarbonyl chloride and benzoyl chloride.

[0022] In one embodiment, the mass ratio of the sulfide to chloropropyltriethoxysilane is 0.4 to 0.6:1, such as 0.4:1, 0.45:1, 0.5:1, 0.55:1, 0.6:1, etc., preferably 0.45 to 0.5:1;

[0023] The amount of the ionic liquid is 20-60% of the mass of chloropropyltriethoxysilane, such as 20%, 30%, 40%, 50%, 60%, etc., preferably 30-55%;

[0024] The phase transfer catalyst is used in an amount of 1 to 10% of the mass of chloropropyltriethoxysilane, such as 1%, 3%, 5%, 7%, 10%, etc., preferably 2 to 5%;

[0025] The amount of the acyl chloride is 45-80% of the mass of chloropropyltriethoxysilane, such as 45%, 50%, 60%, 70%, 80%, etc., preferably 60-80%;

[0026] The amount of the condensation inhibitor is 0.1-5% of the mass of chloropropyltriethoxysilane, such as 0.1%, 1%, 2%, 3%, 4%, 5%, etc., preferably 0.2-2%.

[0027] In one embodiment, the reaction in step (1) is carried out at a temperature of 20 to 80°C, for example, 20°C, 30°C, 40°C, 50°C, 60°C, 70°C, 80°C, etc., preferably 50 to 75°C, and the reaction time is 1 to 4h, for example, 1h, 2h, 3h, 4h, etc., preferably 1.5 to 2.5h; the reaction pressure is 0.005 to 0.01MPaG, for example, 0.005MPaG, 0.007MPaG, 0.009MPaG, 0.01MPaG, etc.

[0028] In one embodiment, the reaction in step (2) is carried out at a temperature of 50 to 140°C, for example, 50°C, 70°C, 90°C, 100°C, 120°C, 140°C, etc., preferably 100 to 120°C, and the reaction time is 2 to 6h, for example, 2h, 3h, 4h, 5h, 6h, etc., preferably 2.5 to 4h; the reaction pressure is 0.005 to 0.01MPaG, for example, 0.005MPaG, 0.007MPaG, 0.009MPaG, 0.01MPaG, etc.

[0029] In a preferred embodiment, the acyl chloride in step (1) is added continuously, preferably dropwise; preferably, the addition time is 0.5 to 1.5 h, such as 0.5 h, 0.8 h, 1 h, 1.3 h, 1.5 h, etc., and the addition time is not included in the reaction time of step (1).

[0030] In a preferred embodiment, in step (1), before the reaction, the system is dehydrated under vacuum until the water content is ≤ 0.1 wt %; preferably, the pressure during the vacuum dehydration process is controlled at -0.095 to -0.09 MPaG.

[0031] In a preferred embodiment, both step (1) and step (2) are carried out in a protective gas environment, such as nitrogen, argon, etc.

[0032] In one embodiment, after the reaction in step (2) is completed, a removal process is further included, such as conventional post-treatment operations such as filtration and distillation. In a specific example, the removal process is filtration, and then vacuum distillation of the oil phase is performed to obtain the product thiocarboxylate silane. The ionic liquid recovered by vacuum distillation can be reused after filtering to precipitate sodium chloride.

[0033] Compared with the prior art, the present invention has the following advantages:

[0034] (1) The ionic liquid used in the present invention has the advantages of good thermal stability and extremely low vapor pressure, and is suitable for reactions at higher temperatures, with a shorter reaction cycle and higher production efficiency.

[0035] (2) The present invention introduces a condensation inhibitor with steric hindrance into the ionic liquid solvent to inhibit the hydrolysis and condensation of the raw material product and residual water, thereby increasing the product yield and purity.

[0036] (3) The present invention avoids the use of water in the raw materials, and there is no problem of treating high-salt organic wastewater during the production process, thereby reducing the cost of treating the three wastes; the ionic liquid used as the solvent is non-toxic and non-flammable, and can be easily separated from the product after post-treatment and can be reused, effectively avoiding the safety and environmental protection problems of traditional organic solvents. DETAILED DESCRIPTION

[0037] The present invention is further described below by means of specific examples. The examples described in the present invention are only used to illustrate the present invention and do not limit the scope of the present invention.

[0038] In the embodiments and comparative examples of the present invention, the sources of the main raw materials used are as follows. Unless otherwise specified, other raw materials and reagents were purchased from commercial sources:

[0039] 1-Butyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium hexafluorophosphate, and 1-butyl-3-methylimidazolium bromide were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0040] Tetrabutylammonium bromide, tetrapropylammonium chloride, and tetrapropylammonium bromide were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0041] Isobutyryl chloride, hexanoyl chloride, and octanoyl chloride were purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0042] Tert-butyldimethylsilyl chloride, tert-butyldiphenylsilyl chloride, triisopropylsilyl chloride: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.;

[0043] Chloropropyltriethoxysilane: purchased from Shanghai MacLean Biochemical Technology Co., Ltd.

[0044] Embodiment 1:

[0045] 1) 270 g of anhydrous sodium sulfide and 280 g of 1-butyl-3-methylimidazolium tetrafluoroborate are put into a reaction kettle and mixed evenly; the reaction kettle is heated to 60° C. in a water bath, and 15 g of tetrabutylammonium bromide is added and stirred evenly; the pressure of the kettle is controlled at -0.095 to -0.09 MPaG, nitrogen is introduced for bubbling, and water is pumped under vacuum until the water content is <0.1 wt%; under nitrogen protection, 480 g of octanoyl chloride is added at a pressure of 0.005 to 0.01 MPaG and 60° C. for 1 hour; and the reaction is continued for 2 hours to obtain an ionic liquid solution of thiocarboxylate.

[0046] 2) The ionic liquid solution of the thiocarboxylate was heated to 110° C., 600 g of chloropropyltriethoxysilane and 4.5 g of tert-butyldimethylchlorosilane were added under the kettle pressure controlled at 0.005-0.01 MPaG, and the reaction was continued with stirring for 4 h. The mixture was cooled to room temperature, filtered to remove salt, and then vacuum distilled to obtain thiocarboxylate silane with a purity of 97.8% and a yield of 95.6% (based on chloropropyltriethoxysilane).

[0047] Embodiment 2:

[0048] 1) 270 g of anhydrous sodium sulfide and 265 g of 1-propyl-3-methylimidazolium hexafluorophosphate are put into a reaction kettle and mixed evenly; the reaction kettle is maintained at 20° C., and 45 g of tetrapropylammonium bromide is added and stirred evenly; the pressure of the kettle is controlled at -0.095 to -0.09 MPaG, nitrogen is introduced for bubbling, and water is pumped under vacuum until the water content is <0.1 wt%; under nitrogen protection, 220 g of isobutyryl chloride is added at a pressure of 0.005 to 0.01 MPaG and 20° C. for 1.5 hours; and the reaction is continued for 4 hours to obtain an ionic liquid solution of thiocarboxylate.

[0049] 2) The ionic liquid solution of the thiocarboxylate was heated to 50° C., 450 g of chloropropyltriethoxysilane and 0.5 g of tert-butyldiphenylchlorosilane were added under the kettle pressure controlled at 0.005-0.01 MPaG, and the reaction was continued with stirring for 6 h. The mixture was cooled to room temperature, filtered to remove salt, and then vacuum distilled to obtain thiocarboxylate silane with a purity of 97.3% and a yield of 92.3% (based on chloropropyltriethoxysilane).

[0050] Embodiment 3:

[0051] 1) 320 g of anhydrous sodium sulfide and 160 g of 1-butyl-3-methylimidazolium bromide are put into a reaction kettle and mixed evenly; the reaction kettle is heated to 80° C. in a water bath, and 10 g of tetrapropylammonium chloride is added and stirred evenly; the pressure of the kettle is controlled at -0.095 to -0.09 MPaG, nitrogen is introduced for bubbling, and water is pumped under vacuum until the water content is less than 0.1 wt %; under nitrogen protection, 510 g of hexanoyl chloride is added at a pressure of 0.005 to 0.01 MPaG and 80° C. for 0.5 h; and the reaction is continued for 1 h to obtain an ionic liquid solution of thiocarboxylate.

[0052] 2) The ionic liquid solution of the thiocarboxylate was heated to 140° C., 810 g of chloropropyltriethoxysilane and 40 g of triisopropylchlorosilane were added under the kettle pressure controlled at 0.005-0.01 MPaG, the reaction was continued with stirring for 2 h, the mixture was cooled to room temperature, filtered to remove salt, and then vacuum distilled to obtain thiocarboxylate silane with a purity of 97.5% and a yield of 90.9% (based on chloropropyltriethoxysilane).

[0053] Comparative Example 1:

[0054] Thiocarboxylate silane was prepared according to the method of Example 1, except that the ionic liquid 1-butyl-3-methylimidazolium tetrafluoroborate was replaced by 1300 g of water to dissolve sodium sulfide, and the reaction was carried out in an aqueous phase. Other operations and conditions remained unchanged to obtain thiocarboxylate silane with a purity of 93.3% and a yield of 88.3% (based on chloropropyltriethoxysilane).

[0055] In addition, unlike Example 1, Comparative Example 1 produces high-salt wastewater with a total mass of about twice that of the product.

[0056] Comparative Example 2:

[0057] Thiocarboxylate silane was prepared according to the method of Example 1, except that tert-butyldimethylsilyl chloride was not added. The purity of the finally obtained thiocarboxylate silane was 94.8%, and the yield was 90.3% (based on chloropropyltriethoxysilane).

[0058] Comparative Example 3:

[0059] Thiocarboxylate silane was prepared according to the method of Example 1, except that tetrabutylammonium bromide was not added. The purity of the finally obtained thiocarboxylate silane was 90.8%, and the yield was 82.3% (based on chloropropyltriethoxysilane).

Claims

1. A method for preparing thiocarboxylate silane, characterized in that: The following steps are involved: (1) mixing a sulfide, an ionic liquid, a phase transfer catalyst and an acyl chloride to react; (2) Adding chloropropyltriethoxysilane and a condensation inhibitor to the reaction system of step (1) to react to obtain thiocarboxylate silane.

2. The preparation method according to claim 1, characterized in that: The sulfide is selected from one or more of sodium sulfide and sodium hydrosulfide, preferably anhydrous sodium sulfide; and / or The mass ratio of the sulfide to chloropropyltriethoxysilane is 0.4-0.6:1, preferably 0.45-0.5:

1.

3. The preparation method according to claim 1, characterized in that: The ionic liquid is selected from imidazolium ionic liquids, preferably one or more of 1-butyl-3-methylimidazolium tetrafluoroborate, 1-propyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium bromide, and 1-hexyl-3-methylimidazolium chloride; and / or The amount of the ionic liquid is 20-60% of the mass of chloropropyltriethoxysilane, preferably 30-55%.

4. The preparation method according to claim 1, characterized in that: The phase transfer catalyst is selected from quaternary ammonium salt compounds, preferably one or more of tetrabutylammonium bromide, tetrapropylammonium chloride, and tetrapropylammonium bromide; and / or The amount of the phase transfer catalyst is 1-10% of the mass of chloropropyltriethoxysilane, preferably 2-5%.

5. The preparation method according to claim 1, characterized in that: The acyl chloride is selected from alkyl acyl chlorides, wherein the alkyl group is preferably a linear or branched alkyl group with C≥3; the acyl chloride is preferably one or more of isobutyryl chloride, hexanoyl chloride, and octanoyl chloride; and / or The amount of the acyl chloride used is 45-80% of the mass of chloropropyltriethoxysilane, preferably 60-80%.

6. The preparation method according to claim 1, characterized in that: The condensation inhibitor is selected from chlorosilane compounds and acyl chloride compounds, preferably one or more of tert-butyldimethylchlorosilane, tert-butyldiphenylchlorosilane, triisopropylchlorosilane, 9-fluorenylmethylcarbonyl chloride and benzoyl chloride; and / or The amount of the condensation inhibitor is 0.1-5% of the mass of chloropropyltriethoxysilane, preferably 0.2-2%.

7. The preparation method according to claim 1, characterized in that: The reaction in step (1) is carried out at a temperature of 20 to 80°C, preferably 50 to 75°C, for a time of 1 to 4 hours, preferably 1.5 to 2.5 hours; and a reaction pressure of 0.005 to 0.01 MPaG; and / or The reaction in step (2) is carried out at a temperature of 50 to 140° C., preferably 100 to 120° C., for a time of 2 to 6 hours, preferably 2.5 to 4 hours; and a reaction pressure of 0.005 to 0.01 MPaG.

8. The preparation method according to claim 1, characterized in that: The acyl chloride in step (1) is added continuously, preferably dropwise; preferably, the addition time is 0.5 to 1.5 hours, and the addition time is not included in the reaction time of step (1).

9. The preparation method according to claim 1, characterized in that: Step (1) Before the reaction, the system is vacuum-dehydrated until the water content is ≤0.1wt%; preferably, the pressure of the vacuum dehydration process is controlled at -0.095 to -0.09MPaG.

10. The preparation method according to claim 1, characterized in that: Both step (1) and step (2) are carried out in a protective gas environment.

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