Preparation method and application of supported perfluorosulfonic acid resin catalyst

Abstract

The application relates to a preparation method and application of a supported perfluorosulfonic acid resin catalyst, wherein after powder perfluorosulfonic acid resin is prepared into a 5wt% perfluorosulfonic acid solution, the perfluorosulfonic acid solution is loaded on a titanium dioxide aerogel to prepare a PFSA@TiO2 catalyst, and the reaction is carried out in a solvent-free state; the synthesis process is simple and convenient, the product is easy to separate, the yield and purity are relatively high, the product is friendly to the environment, and the production safety is high. Compared with the prior art, the supported perfluorosulfonic acid resin catalyst developed by the application has relatively large specific surface area, more accessible acid sites, good catalytic performance and other advantages.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalyst, in particular to a preparation method and application of a supported perfluorosulfonic acid resin catalyst. BACKGROUND

[0002] Hydroamination of a double or triple bond to add an N-H bond is one of the most important methods for C-N bond construction, and is also one of the most atom-economic methods for forming value-added N-containing compounds from relatively inexpensive and ubiquitous amines and olefins. This reaction has also been found to have a wide range of applications in the synthesis of natural products, drugs, dyes, fine chemicals and surfactants.

[0003] Ethyl 3-[(pyridin-2-yl)amino]propanoate is an important intermediate of dabigatran, which is formed by the hydroamination of ethyl acrylate with 2-aminopyridine. The effective catalysts used in such reactions include CsF-Si(O-Et)4, triflic acid, etc. Although these strategies are feasible, they still have disadvantages such as complex catalyst system, low yield, etc. In addition, the frequency of catalyst recovery is still limited. Obviously, such reactions still face challenges. Therefore, it is still necessary to find a more mild and environmentally friendly solid catalyst for catalyzing the hydroamination reaction of 2-aminopyridine with ethyl acrylate.

[0004] Perfluorosulfonic acid (PFSA) resin is a solid superacid, which has good chemical stability and thermal stability, so that the material can adapt to highly severe reaction environment. The strong electronegativity of fluorine atoms in the molecule makes the sulfonic acid exhibit very strong acidity and has very strong catalytic activity. It has been used to catalyze many organic reactions, such as esterification, hydrolysis, condensation and rearrangement, etc., and has been proved to have good catalytic effect. In addition, perfluorosulfonic acid resin is superior to other acid catalysts in many aspects, such as easy recovery after reaction, high selectivity, small corrosion, and easy continuous production. However, it also has disadvantages: the specific surface area of the powdered perfluorosulfonic acid resin is very low, which leads to most of the sulfonic acid groups active sites being buried inside the polymer, which cannot fully contact with the substrate molecules, affecting the reaction performance. Chinese patent CN105665018B discloses a preparation method and application of a composite solid superacid catalyst, which adopts a sol-gel method to prepare solid particles of SiO2 supported perfluorosulfonic acid resin, and then calcines the solid particles to obtain a perfluorosulfonic acid resin / SiO2 composite solid superacid catalyst, but SiO2 itself does not have catalytic activity and is an inert carrier, and the catalytic effect needs to be further improved. SUMMARY

[0005] The present application aims at overcoming the defects of the prior art and providing a supported perfluorosulfonic acid resin catalyst, which can fully exert the excellent acid catalytic performance of the PFSA resin and further improve the catalytic performance by loading TiO2 which has a synergistic catalytic effect with the PFSA.

[0006] The object of the present application can be achieved by the following technical solutions.

[0007] In order to overcome the defects of the PFSA resin and exert the excellent acid catalytic performance of the PFSA resin, the present application prepares an organic-inorganic composite solid acid based on the PFSA resin, in which the excellent acid catalytic performance of the PFSA resin can be fully exerted, and after the reaction is completed, the catalyst can be recovered and reused by simple physical separation.

[0008] A preparation method of a supported perfluorosulfonic acid resin catalyst, which coats a perfluorosulfonic acid resin solution on a titanium dioxide aerogel, dries and crushes to obtain a perfluorosulfonic acid resin / TiO2 catalyst.

[0009] Further, the mass ratio of the perfluorosulfonic acid resin to the aerogel titanium dioxide is 1:4-4:1, preferably 1:1.

[0010] Further, the perfluorosulfonic acid resin solution is a 5wt% perfluorosulfonic acid solution.

[0011] Further, the titanium dioxide aerogel is prepared by the following method: using a titanium source, deionized water, ethanol, and N,N-dimethylformamide as raw materials, adjusting the pH to 2.5 to obtain a sol, then adjusting the pH of the system to 7, and reacting at 40℃ for 25min to obtain the titanium dioxide aerogel, and calcining the prepared titanium dioxide aerogel at high temperature.

[0012] Further, the mass ratio of the titanium source, deionized water, anhydrous ethanol, and N,N-dimethylformamide is 1:(2-4):6:0.5, preferably 1:4:6:0.5, and the prepared aerogel titanium dioxide is calcined at 500℃ for 2h for subsequent loading.

[0013] Further, the calcination temperature is 500℃.

[0014] Further, the calcination time is 2h.

[0015] Further, after loading, the perfluorosulfonic acid resin catalyst is separated, dried, and reused, the drying temperature is 60-80℃, the drying time is 5-8h, and the catalyst can be recycled.

[0016] A supported perfluorosulfonic acid resin catalyst is prepared by the above method.

[0017] Further, the ion exchange capacity of the perfluorosulfonic acid resin is 0.7-2.2 mmol / g.

[0018] Further, the perfluorosulfonic acid resin is supported on the titanium dioxide aerogel by dip coating.

[0019] The application of a supported perfluorosulfonic acid resin catalyst in catalyzing the hydroxylamination reaction of 2-aminopyridine and ethyl acrylate.

[0020] Further, the molar ratio of 2-aminopyridine to ethyl acrylate is 1:1-1:3, preferably the molar ratio of 2-aminopyridine to ethyl acrylate is 1:1.3.

[0021] Further, the temperature of the hydroxylamination reaction is 80-160℃, and the reaction time is 10-23h, the reaction time of the series of reactions is accelerated with the increase of the reaction temperature in the appropriate temperature range, and too short reaction time will result in too low conversion rate, and further preferably the reaction temperature of the hydrogenation amination reaction is 140℃, and the reaction time is 23h.

[0022] Further, during catalysis, the molar percentage content of the single perfluorosulfonic acid resin catalyst in the supported perfluorosulfonic acid resin catalyst relative to the 2-aminopyridine and ethyl acrylate to be catalyzed is 1mol%-9mol%, preferably the molar percentage content of the perfluorosulfonic acid resin is 5mol%.

[0023] Compared with the prior art, the application has the following advantages and beneficial effects:

[0024] (1) A brand new supported perfluorosulfonic acid resin catalyst is prepared, 5% perfluorosulfonic acid resin solution is supported on the aerogel titanium dioxide to prepare a supported catalyst, the catalytically active carrier (titanium dioxide) is supported on the perfluorosulfonic acid resin, and the synergistic effect of the Bronsted acid and the Lewis acid is embodied.

[0025] (2) Good catalytic effect: the supported perfluorosulfonic acid resin catalyst developed in the application has a relatively large specific surface area, more accessible acid sites, good catalytic performance, can be used repeatedly, and the carrier titanium dioxide has catalytic activity, further increasing the catalytic performance and improving the conversion rate, the supported catalyst exhibits good catalytic performance in the hydrogenation amination reaction of 2-aminopyridine and ethyl acrylate, and is easy to separate from the product. DETAILED DESCRIPTION

[0026] The application will be described in detail below in combination with specific embodiments.

[0027] In the following examples, unless otherwise specified, the raw reagents or processing techniques are all conventional commercially available products or conventional processing techniques in the art.

[0028] Example 1

[0029] This example provides a preparation method and catalytic application of a supported perfluorosulfonic acid resin catalyst. The preparation method is as follows:

[0030] (1) Preparation of perfluorosulfonic acid solution: Dissolve perfluorosulfonic acid resin powder (manufactured by Shandong Dongyue Future Hydrogen Energy Materials Co., Ltd.) in deionized water and isopropanol at a mass ratio of 1:1 to prepare a 5wt% perfluorosulfonic acid solution;

[0031] (2) Preparation of titanium dioxide aerogel: Use tetraethyl orthotitanate as the titanium source, deionized water, anhydrous ethanol, and N,N-dimethylformamide as raw materials, and follow the molar ratio of 1:4:6:0.5 to prepare the sol, adjust the pH to 2.5 with hydrochloric acid, and obtain the sol at 40°C. Then, add ammonia water to adjust the pH of the system to 7 and react for 25 min at 40°C to obtain the aerogel titanium dioxide. The prepared aerogel titanium dioxide is calcined at 500°C for 2h for subsequent loading.

[0032] (3) Preparation of supported perfluorosulfonic acid resin catalyst:

[0033] Load the 5wt% perfluorosulfonic acid solution and the titanium dioxide aerogel at a mass ratio of 4:1 by dip coating, stir and mix uniformly, then place in an 80°C oven to dry for 1h, and grind to obtain the PFSA@TiO2 catalyst.

[0034] The application experiment is as follows:

[0035] Weigh the supported catalyst (PFSA@TiO2 catalyst) according to the amount of 5mol% perfluorosulfonic acid, add the supported catalyst to the mixture of 2-aminopyridine (1mmol) and ethyl acrylate (1.3mmol), heat and stir the mixture, the temperature of the hydroxylamine reaction is 120°C, and the reaction time is 23h.

[0036] The whole reaction process is monitored by TLC until the reaction is completed. To detect the yield of the hydroxylamine reaction product, add ethyl acetate to the mixture, stir to dissolve, then use a dropper to transfer the solution to a rotary evaporation flask, add silica gel to the rotary evaporation flask to load the product, and use a rotary evaporator to evaporate. The product (3-[(pyridin-2-yl)amino]propionic acid ethyl ester) is separated by column chromatography, and the yield is 57.94%.

[0037] Examples 2-5

[0038] The embodiment provides a preparation and application of a supported perfluorosulfonic acid resin catalyst, and the difference from the embodiment 1 is that in the preparation of the supported perfluorosulfonic acid resin catalyst in step (3), 5wt% perfluorosulfonic acid solution and titanium dioxide aerogel are fed in a mass ratio of 2:1, 1:1, 1:2 and 1:4, and other steps, feeding, reagents and the like are the same as those in the embodiment 1. The experimental results and parameters are shown in Table 1. As shown in the table, when the mass ratio of the perfluorosulfonic acid solution to the titanium dioxide aerogel is 1:1, the catalytic effect is the best.

[0039] Table 1: Experimental parameters and catalytic effects of the embodiments 1-5

[0040]

[0041]

[0042] Embodiments 6-10

[0043] The embodiment provides a preparation and application of a supported perfluorosulfonic acid resin catalyst, and the difference from the embodiment 3 is that in the application experiment, the hydroxylamine reaction is carried out at a reaction temperature of 80℃, 100℃, 130℃, 140℃ and 160℃ respectively, and other steps, feeding, reagents and the like are the same as those in the embodiment 1. The experimental results and parameters are shown in Table 2. As shown in the table, when the hydroxylamine reaction temperature is 140℃, the catalytic effect is the best.

[0044] Table 2: Experimental parameters and catalytic effects of the embodiments 1 and 6-10

[0045]

[0046] Embodiments 11-14

[0047] The embodiment provides a preparation and application of a supported perfluorosulfonic acid resin catalyst, and the difference from the embodiment 9 is that in the application experiment, the hydroxylamine reaction is carried out by feeding ethyl acrylate in an amount of 1mmol, 1.5mmol, 2mmol and 3mmol respectively, and other steps, feeding, reagents and the like are the same as those in the embodiment 1. The experimental results and parameters are shown in Table 3.

[0048] Table 3: Hydroxylamine reaction parameters and catalytic effects of the embodiments 1 and 11-14

[0049]

[0050]

[0051] Comparative examples 1-5

[0052] Comparative Example 1-5 directly used perfluorosulfonic acid resin (1 mol%, 3 mol%, 5 mol%, 7 mol%, 9 mol%) to catalyze the hydroxylamination reaction of 2-aminopyridine (1 mmol) and ethyl acrylate (1.3 mmol), and the experimental results and parameters are shown in Table 4:

[0053] Table 4 Hydroxylamination reaction parameters and catalytic effect of Comparative Example 1-5

[0054]

[0055] As can be seen from Table 4, compared with the supported perfluorosulfonic acid resin catalyst Example 1: 57.94%, the effect of using perfluorosulfonic acid resin powder alone is poorer, which shows that the loading of titanium dioxide has better catalytic effect, and the two synergistically catalyze, significantly improving the catalytic efficiency.

[0056] Comparative Example 6

[0057] Comparative Example 6 directly used aerogel TiO2 powder to catalyze the hydroxylamination reaction of 2-aminopyridine (1 mmol) and ethyl acrylate (1.3 mmol), the reaction temperature was 120°C, the reaction time was 23h, the whole reaction process was monitored by TLC until the reaction was completed. Ethyl acetate was added to the mixture, stirred and dissolved, then the solution was removed to a rotary evaporation flask with a dropper, silica gel was added to the rotary evaporation flask to load the product, rotary evaporation was performed, and the product was separated by column chromatography. The yield of the product was 31.24%, which can be seen, compared with the supported perfluorosulfonic acid resin catalyst Example 1: 57.94%, the effect of using aerogel TiO2 powder alone is poorer, which shows that the loading of titanium dioxide has better catalytic effect.

[0058] The above description of the embodiments is to facilitate those of ordinary skill in the art to understand and use the invention. Those skilled in the art can easily make various modifications to these embodiments, and apply the general principles described herein to other embodiments without having to go through creative labor. Therefore, the present invention is not limited to the above embodiments, and improvements and modifications made by those skilled in the art without departing from the scope of the invention should be within the scope of protection of the invention.

Claims

1. Use of a supported perfluorosulfonic acid resin catalyst, characterized in that, The supported perfluorosulfonic acid resin catalyst is used for catalyzing the hydroaminomerization reaction of 2-aminopyridine and ethyl acrylate; the temperature of the hydroaminomerization reaction is 80-160℃; The preparation method of the supported perfluorosulfonic acid resin catalyst comprises: coating a perfluorosulfonic acid resin solution on a titanium dioxide aerogel, drying and crushing to obtain a perfluorosulfonic acid resin / TiO2 catalyst; the mass ratio of the perfluorosulfonic acid resin solution to the aerogel titanium dioxide is 1:4-4:

1.

2. Use of a supported perfluorosulfonic acid resin catalyst according to claim 1, characterized in that, The perfluorosulfonic acid resin solution is a 5wt% perfluorosulfonic acid solution.

3. Use of a supported perfluorosulfonic acid resin catalyst according to claim 1, characterized in that, The titanium dioxide aerogel is prepared by the following method: taking a titanium source, deionized water, ethanol and N,N-dimethylformamide as raw materials, adjusting the pH to 2.5 to obtain a sol, then adjusting the pH of the system to 7, and reacting at 40℃ for 25min to obtain the titanium dioxide aerogel, and high-temperature calcining the prepared titanium dioxide aerogel.

4. Use of a supported perfluorosulfonic acid resin catalyst according to claim 3, characterized in that, The mass ratio of the titanium source, deionized water, ethanol and N,N-dimethylformamide is 1:(2-4):6:0.

5.

5. Use of a supported perfluorosulfonic acid resin catalyst according to claim 3, characterized in that, The calcining temperature is 500℃.

6. Use of a supported perfluorosulfonic acid resin catalyst according to claim 3, characterized in that, The calcining time is 2h.

7. Use of a supported perfluorosulfonic acid resin catalyst according to claim 1, characterized in that, The reaction time of the hydroaminomerization reaction is 10-23h.

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