A method for synthesizing tert-butyl 4-triethoxysilylbutyrate

Abstract

The application belongs to the technical field of organic synthesis and particularly relates to a synthesis method of tert-butyl 4-triethoxysilyl butyrate. The synthesis method is that tiglic acid is reacted with sulfoxide chloride, then reacted with tert-butyl alcohol to obtain tert-butyl but-3-enoate, and finally, tert-butyl but-3-enoate is reacted with triethoxysilane with platinum dioxide as a catalyst to obtain tert-butyl 4-triethoxysilyl butyrate. The synthesis method is simple in operation, low in raw material price, low in catalyst consumption, high in yield and high in purity, and is suitable for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, specifically relating to a method for synthesizing tert-butyl 4-triethoxysilylbutyrate. Background Technology

[0002] Polysiloxane (RSiO1.5) n Polysiloxanes, with their ease of preparation and excellent physicochemical properties, have attracted increasing attention in the fields of polymer and materials science in recent years. Methods for introducing functional groups into these materials are limited to substituents R, which typically do not react with alkoxysilanes, silanols, or catalysts under sol-gel polymerization conditions. Therefore, reactive functional groups are generally introduced into polysiloxanes through chemical modification, usually with hydroxyl, vinyl, and allyl substituted polysiloxanes, and some examples include aminoalkyl, epoxy, isocyanate, and thiol groups. Alternatively, the R group can be modified using methods that stabilize the polymerization conditions and deprotect it after polymer formation. Organic carboxylic acids and carboxylic acids are useful functional groups attached to polysiloxanes, enabling the preparation of chemically and thermally stable ion exchange resins for the removal of heavy metals and organic amines. Tert-butyl 4-triethoxysilylbutyrate is an important intermediate in the synthesis of carboxyl-containing polysiloxanes.

[0003] Kamyar Rahimian et al. (Soluble, High Molecular Weight Polysilsesquioxanes with Carboxylate Functionalities, 2002, 35, 2452-2454) reported a method for the synthesis of tert-butyl 4-triethoxysilylbutyrate. Tert-butyl 4-triethoxysilylbutyrate was synthesized in 95% yield from allylbutyrate and triethoxysilane in benzene as a reaction solvent under the catalysis of chloroplatinic acid. However, this method uses chloroplatinic acid as a catalyst, which is expensive and unsuitable for industrial-scale production. Furthermore, benzene, as a reaction solvent, is highly toxic and environmentally harmful.

[0004] Therefore, there is an urgent need in the field for a method to synthesize tert-butyl 4-triethoxysilylbutyrate suitable for industrial production. Summary of the Invention

[0005] This invention addresses the problems existing in the prior art by providing a method for synthesizing tert-butyl 4-triethoxysilylbutyrate.

[0006] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0007] A method for synthesizing tert-butyl 4-triethoxysilylbutyrate, the synthetic route of which is as follows:

[0008]

[0009] The method includes the following steps:

[0010] (1) First, react crotonic acid with thionyl chloride to obtain crotonyl chloride;

[0011] (2) Crotonyl chloride is then reacted with tert-butanol to obtain tert-butyl butyrate;

[0012] (3) Finally, using platinum dioxide as a catalyst, tert-butyl butyrate is reacted with triethoxysilane to obtain the product.

[0013] Preferably, the mass ratio of crotonic acid to thionyl chloride in step (1) is 1:1-2.

[0014] Preferably, the reaction in step (1) involves adding thionyl chloride to crotonic acid, the reaction temperature is 70-90°C, the reaction time is 2-4 h, and the reaction is followed by distillation and purification after the reaction is completed.

[0015] Preferably, the reaction temperature in step (2) is -5℃ to 5℃, and the reaction time is 10-20 h.

[0016] More preferably, the temperature of the reaction in step (2) is -1℃ to 1℃, and the reaction time is 10-12 h.

[0017] Preferably, a solvent is added during the reaction in step (2), the solvent including triethylamine and methyl tert-butyl ether, and the reaction is quenched, separated, the aqueous phase is extracted, the organic phase is combined and distilled after the reaction is completed.

[0018] Preferably, the mass-to-volume ratio of crotonyl chloride, tert-butanol, triethylamine, and methyl tert-butyl ether is 40-60 g: 30-60 g: 50-60 g: 1-2 L, sodium bicarbonate is added during quenching, methyl tert-butyl ether is used as the extraction solvent, and the extraction is performed 2-3 times.

[0019] Preferably, the volume concentration of platinum dioxide in the solution in step (3) is 100-200 ppm, toluene is added during the reaction, the reaction temperature is 80-120℃, the reaction time is 10-12 h, and the reaction is filtered and distilled after the reaction is completed.

[0020] Preferably, the mass-to-volume ratio of tert-butyl butyrate, triethoxysilane, and toluene is 20-40 g: 40-60 mL: 200-400 mL.

[0021] Compared with the prior art, the present invention has the following beneficial effects:

[0022] The method for synthesizing tert-butyl 4-triethoxysilylbutyrate provided by this invention is simple to operate, uses inexpensive raw materials, selects platinum dioxide as a catalyst, requires less catalyst, has high yield and high purity, and is suitable for industrial production. It has significant advantages over existing methods for preparing tert-butyl 4-triethoxysilylbutyrate. Attached Figure Description

[0023] Figure 1 The proton NMR spectrum of the product prepared in Example 1 ( 1 H NMR). Detailed Implementation

[0024] It is worth noting that the raw materials used in this invention are all commercially available products.

[0025] Example 1

[0026] (1) Preparation of crotonyl chloride (compound II)

[0027] 50 g of crotonic acid (compound I) was added to a reaction flask, followed by the dropwise addition of 82 g of thionyl chloride (SOCl2). After the addition was complete, the reaction continued for 3 h. A sample was taken for control, and the remaining raw material was ≤1%. Excess thionyl chloride was removed by vacuum distillation using a water pump. Distillation was continued to obtain crotonyl chloride (compound II) with a yield of 90% and a GC value of 95%.

[0028] (2) Preparation of tert-butyl butyrate (compound III)

[0029] At room temperature, 37 g of tert-butanol (tBuOH) and 55 g of triethylamine (TEA) were added to a reaction flask, followed by 1 L of methyl tert-butyl ether (MTBE). The temperature was maintained at 0°C, and 50 g of crotonyl chloride (compound II) was added dropwise to the reaction flask. The reaction was maintained at this temperature for 12 h. After the reaction was complete, 100 mL of saturated sodium bicarbonate (Na₂HCO₃) was added to quench the reaction. After separation, the aqueous phase was extracted twice with 200 mL of methyl tert-butyl ether (MTBE). The organic phases were combined and distilled under reduced pressure to obtain tert-butyl butyrate (compound III) with a yield of 95% and a GC yield of 98%.

[0030] (3) Preparation of tert-butyl 4-triethoxysilylbutyrate (compound IV)

[0031] 30 g of tert-butyl butyrate (compound III) was added to a reaction flask, followed by 300 mL of toluene, 46.8 g of triethoxysilane (TES), and 8.5 mg of platinum dioxide (PtO2). The reaction was carried out at 100 °C for 12 h. After the reaction was completed, the catalyst was removed by filtration, and the product was distilled under reduced pressure using an oil pump to obtain tert-butyl 4-triethoxysilylbutyrate (compound IV) with a yield of 98%, a GC content of 99%, and a moisture content of ≤0.5%.

[0032] The tert-butyl 4-triethoxysilylbutyrate (compound IV) prepared in this example 1 H NMR spectrum, such as Figure 1 As shown.

[0033] Example 2

[0034] (1) Preparation of crotonyl chloride (compound II)

[0035] 50 g of crotonic acid (compound I) was added to the reaction flask, followed by the dropwise addition of 100 g of thionyl chloride (SOCl2). After the addition was complete, the reaction continued for 2 h. A sample was taken for control, and the remaining raw material was ≤1%. Excess thionyl chloride was removed by vacuum distillation using a water pump. Distillation was continued to obtain crotonyl chloride (compound II) with a yield of 91% and a GC value of 94%.

[0036] (2) Preparation of tert-butyl butyrate (compound III)

[0037] At room temperature, 50 g of tert-butanol (tBuOH) and 60 g of triethylamine (TEA) were added to a reaction flask, followed by 1 L of methyl tert-butyl ether (MTBE). The temperature was maintained at 0 °C. 50 g of crotonyl chloride (compound II) was weighed and added dropwise to the reaction flask, and the reaction was maintained at this temperature for 20 h. After the reaction was complete, 100 mL of saturated sodium bicarbonate (Na₂HCO₃) was added to quench the reaction. After separation, the aqueous phase was extracted twice with 200 mL of methyl tert-butyl ether (MTBE). The organic phases were combined and distilled under reduced pressure to obtain tert-butyl butyrate (compound III) in 90% yield (GC 95%).

[0038] (3) Preparation of tert-butyl 4-triethoxysilylbutyrate (compound IV)

[0039] 20 g of tert-butyl butyrate (compound III) was added to a reaction flask, followed by 200 mL of toluene, 40 mL of triethoxysilane (TES), and 5.5 mg of platinum dioxide (PtO2). The reaction was carried out at 80 °C for 12 h. After the reaction was completed, the catalyst was removed by filtration, and the product was distilled under reduced pressure using an oil pump to obtain tert-butyl 4-triethoxysilylbutyrate (compound IV), with a yield of 96%, a GC content of 94%, and a moisture content of ≤0.5%.

[0040] Example 3

[0041] (1) Preparation of crotonyl chloride (compound II)

[0042] 50 g of crotonic acid (compound I) was added to the reaction flask, followed by the dropwise addition of 50 g of thionyl chloride (SOCl2). After the addition was complete, the reaction continued for 4 h. A sample was taken for control, and the remaining raw material was ≤1%. Excess thionyl chloride was removed by vacuum distillation using a water pump. Distillation was continued to obtain crotonyl chloride (compound II) with a yield of 85% and a GC value of 92%.

[0043] (2) Preparation of tert-butyl butyrate (compound III)

[0044] At room temperature, 60 g of tert-butanol (tBuOH) and 50 g of triethylamine (TEA) were added to a reaction flask, followed by 2 L of methyl tert-butyl ether (MTBE). The temperature was maintained at 0°C, and 50 g of crotonyl chloride (compound II) was added dropwise to the reaction flask. The reaction was maintained at this temperature for 20 h. After the reaction was complete, 100 mL of saturated sodium bicarbonate (Na₂HCO₃) was added to quench the reaction. After separation, the aqueous phase was extracted three times with 200 mL of methyl tert-butyl ether (MTBE). The organic phases were combined and distilled under reduced pressure to obtain tert-butyl butyrate (compound III) in 86% yield (GC 90%).

[0045] (3) Preparation of tert-butyl 4-triethoxysilylbutyrate (compound IV)

[0046] 40 g of tert-butyl butyrate (compound III) was added to a reaction flask, followed by 400 mL of toluene, 60 mL of triethoxysilane (TES), and 13.4 mg of platinum dioxide (PtO2). The reaction was carried out at 120 °C for 10 h. After the reaction was completed, the catalyst was removed by filtration, and the product was distilled under reduced pressure using an oil pump to obtain tert-butyl 4-triethoxysilylbutyrate (compound IV) with a yield of 95%, a GC content of 98%, and a moisture content of ≤0.5%.

[0047] Comparative Example 1

[0048] (1) Preparation of crotonyl chloride (compound II)

[0049] 50 g of crotonic acid (compound I) was added to a reaction flask, followed by the dropwise addition of 82 g of thionyl chloride (SOCl2). After the addition was complete, the reaction continued for 3 h. A sample was taken for control, and the remaining raw material was ≤1%. Excess thionyl chloride was removed by vacuum distillation using a water pump. Distillation was continued to obtain crotonyl chloride (compound II) with a yield of 90% and a GC value of 95%.

[0050] (2) Preparation of tert-butyl butyrate (compound III)

[0051] At room temperature, 37 g of tert-butanol (tBuOH) and 55 g of triethylamine (TEA) were added to a reaction flask, followed by 1 L of methyl tert-butyl ether (MTBE). The temperature was maintained at 0°C, and 50 g of crotonyl chloride (compound II) was added dropwise to the reaction flask. The reaction was maintained at this temperature for 12 h. After the reaction was complete, 100 mL of saturated sodium bicarbonate (Na₂HCO₃) was added to quench the reaction. After separation, the aqueous phase was extracted twice with 200 mL of methyl tert-butyl ether (MTBE). The organic phases were combined and distilled under reduced pressure to obtain tert-butyl butyrate (compound III) with a yield of 95% and a GC yield of 98%.

[0052] (3) Preparation of tert-butyl 4-triethoxysilylbutyrate (compound IV)

[0053] 30 g of tert-butyl butyrate (compound III) was added to a reaction flask, followed by 150 mL of benzene, 38.1 mL of triethoxysilane (TES), and 8.6 mg of chloroplatinic acid. The reaction was carried out at room temperature for 12 h. After the reaction was completed, the catalyst was removed by filtration, and the product was distilled under reduced pressure using an oil pump to obtain tert-butyl 4-triethoxysilylbutyrate (compound IV) with a yield of 95%, a GC content of 90%, and a moisture content of ≤1%.

[0054] Finally, it should be noted that the above content is only used to illustrate the technical solution of the present invention, and is not intended to limit the scope of protection of the present invention. Simple modifications or equivalent substitutions made by those skilled in the art to the technical solution of the present invention do not depart from the essence and scope of the technical solution of the present invention.

Claims

1. A method for synthesizing tert-butyl 4-triethoxysilylbutyrate, characterized in that, The steps are as follows: (1) First, react crotonic acid with thionyl chloride to obtain crotonyl chloride; (2) Crotonyl chloride is then reacted with tert-butanol to obtain tert-butyl butyrate; (3) Finally, using platinum dioxide as a catalyst, tert-butyl butyrate is reacted with triethoxysilane to obtain the product; In step (2), the reaction temperature is 0°C and the reaction time is 10 h or 20 h; a solvent is also added during the reaction, which is triethylamine and methyl tert-butyl ether, and the mass-volume ratio of crotonyl chloride, tert-butanol, triethylamine and methyl tert-butyl ether is 50 g:37 g:55 g:1 L or 50 g:50 g:60 g:1 L; In step (3), the reaction temperature is 80°C or 100°C, and the reaction time is 12 h.

2. The synthesis method according to claim 1, characterized in that, The mass ratio of crotonic acid to thionyl chloride in step (1) is 1:1-2.

3. The synthesis method according to claim 1, characterized in that, The reaction described in step (1) involves adding thionyl chloride to crotonic acid. The reaction temperature is 70-90℃ and the reaction time is 2-4 h. After the reaction is completed, the mixture is distilled and purified.

4. The synthesis method according to claim 1, characterized in that, After the reaction described in step (2) is completed, quenching, layering, extraction of the aqueous phase, merging of the organic phase and distillation are performed.

5. The synthesis method according to claim 4, characterized in that, Sodium bicarbonate is added during quenching, methyl tert-butyl ether is used as the solvent for extraction, and the extraction is performed 2-3 times.

6. The synthesis method according to claim 1, characterized in that, In step (3), the volume concentration of platinum dioxide in the solution is 100-200 ppm. Toluene is added during the reaction, and the reaction is completed by filtration and distillation.

7. The synthesis method according to claim 1, characterized in that, The mass-to-volume ratio of tert-butyl butyrate, triethoxysilane, and toluene is 20-40 g: 40-60 mL: 200-400 mL.

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