A mesoporous material limited ruthenium catalyst and application thereof in cyclization of diamine to synthesize piperidine derivatives

Abstract

The present application relates to a kind of mesoporous material limited ruthenium catalyst and application in the cyclization of diamine synthesis piperidine derivative.The catalyst is successfully loaded with metal ruthenium in the pore of mesoporous material, realizes the space limited effect of metal particle, reduces metal particle size, improves the utilization of metal atom, so as to improve the efficiency of catalyst.In the cyclization of diamine synthesis piperidine derivative reaction, the catalyst exhibits the advantages of high conversion, high selectivity, high stability.The method not only reduces the generation of byproduct, improves the yield of reaction, but also has the advantages of mild reaction condition, environment-friendly, with wide application prospect.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of catalysis and organic synthesis, in particular to a mesoporous material confined ruthenium catalyst and its application in the catalytic cyclization of diamines to synthesize piperidine derivatives. BACKGROUND

[0002] The field of organic synthesis has been pursuing efficient and environmentally friendly synthesis methods, especially for catalytic reactions to prepare important compounds. In this context, supported metal catalysts as one of the key tools for organic synthesis, their design and application have always been an important direction of research. In order to improve the efficiency, selectivity and stability of the catalyst, researchers have been exploring new catalyst design and preparation methods.

[0003] Traditional catalyst supports are limited in surface area, pore size distribution and uniformity of loading, which to some extent hinders the improvement of the performance and efficiency of the catalyst. To address this challenge, mesoporous materials as a new class of materials with ordered pore structure and high specific surface area have attracted widespread interest from researchers. These materials not only provide more active sites, but also have larger reaction surface area, providing an ideal support for catalytic reactions. Especially in the field of metal catalysts, supported metal catalysts achieve spatial confinement effect of metal particles by precisely loading metal catalysts on mesoporous materials. This effect not only helps to optimize the reaction conditions, but also significantly improves the utilization rate of metal atoms. Such technological innovation provides new possibilities for improving the efficiency of catalytic systems, and also opens up new avenues for research and application in the field of organic synthesis.

[0004] However, the pore size of mesoporous materials is usually larger (> 2 nm), while the size of noble metal clusters is smaller (< 2 nm). Loading noble metal clusters on mesoporous molecular sieves often faces a series of difficulties. Traditional impregnation method is difficult to achieve uniform loading of noble metal clusters in aqueous solution of metal salt, because in this process, metal clusters are prone to grow and form larger particles (Angew. Chem. 2008, 120 (33), 6325-6328 and Catal. Today. 2011, 174(1), 121-126.). Especially in the process of hydrogen reduction, metal particles often migrate to the outside of the support, resulting in their aggregation into large particles. This phenomenon not only affects the dispersion of metal clusters loaded on mesoporous materials, but also may cause metal particles to block the pore structure of the support, reducing the catalytic performance of mesoporous materials (ChemCatChem 2013, 5(10), 2822-2826). Therefore, how to achieve uniform loading of metal clusters on mesoporous materials is still a challenging problem. SUMMARY

[0005] The present application provides a mesoporous material limited ruthenium catalyst and its application in catalyzing diamine cyclization to synthesize piperidine derivatives to solve the above technical problems. The by-product 2-methyl-1, 5-pentanediamine produced in the process of preparing adiponitrile by butadiene method is used to synthesize piperidine derivatives under the catalysis of the ruthenium catalyst. The catalyst can be effectively applied to catalyze diamine cyclization to synthesize piperidine derivatives, and provides an innovative and feasible way for the preparation of high value-added fine chemical intermediates.

[0006] The technical solution of the present application to solve the above technical problems is as follows:

[0007] A mesoporous material limited ruthenium catalyst, comprising a mesoporous material and metal ruthenium loaded in the pore channel of the mesoporous material, the loading of the metal ruthenium is realized by subjecting the metal particles to the spatial confinement effect of the mesoporous material to reduce the size of the metal particles, thereby improving the utilization rate of metal atoms; in the mesoporous material limited ruthenium catalyst, the loading amount of the active component ruthenium is 0.5-10wt.%, preferably 2wt.%.

[0008] The mesoporous material is mesoporous alumina, mesoporous zirconia, mesoporous titania, mesoporous silicate, mesoporous molecular sieve, mesoporous carbon or mesoporous organic polymer, preferably mesoporous molecular sieve.

[0009] The metal precursor of ruthenium is triruthenium dodecacarbonyl.

[0010] The mesoporous material limited ruthenium catalyst of the present application is prepared by slow evaporation method, first introducing a metal ruthenium precursor into the mesoporous material; then controlling the loading process method to load the metal ruthenium in the pore channel of the mesoporous material to obtain a ruthenium loading precursor; finally controlling the reduction conditions to realize the spatial confinement effect of the metal particles. Specifically, it includes the following steps:

[0011] 1) Dissolve the metal precursor of ruthenium in acetone and obtain solution A by ultrasonic treatment;

[0012] 2) Slowly and uniformly add the solid powder of the mesoporous material to the solution A in a stirring state, and stir vigorously at room temperature until there is no obvious solid precipitation at the bottom of the mixture, and then perform ultrasonic treatment;

[0013] 3) Slowly heat the mixture obtained by ultrasonic treatment at 55-65℃ for 20-25 hours, and obtain the precursor of the ruthenium catalyst after drying;

[0014] 4) Grind the precursor obtained in step 3), and then reduce it at 200-500℃ for 1-3 hours under 5% H2 / Ar atmosphere to finally obtain the mesoporous material limited ruthenium catalyst.

[0015] Another object of the present application is to provide an application of the mesoporous material confined ruthenium catalyst prepared by the above method in catalyzing the cyclization of diamines to synthesize piperidine derivatives.

[0016] The method for catalyzing the cyclization of diamines to synthesize piperidine derivatives by the mesoporous material confined ruthenium catalyst comprises the following steps:

[0017] 1) The mesoporous material confined ruthenium catalyst, diamine substrate and solvent are added into a reactor; the solvent is one or more of water, cyclohexane, ethanol, tetrahydrofuran and acetonitrile; the molar amount of the supported Ru catalyst is 0.025-2.5% of the molar amount of 1,5-diamino-2-methylpentane.

[0018] 2) After ensuring that the residual air in the system is removed by three times of air replacement, 0.1-3 MPa H2 is introduced;

[0019] 3) The reactor is placed on a magnetic stirrer, heated from room temperature to 50-200℃, and reacted for 1-24 h;

[0020] 4) After completion, the reactor is cooled to room temperature, and the solid-liquid mixture is separated by filtration to obtain the piperidine derivative. The diamine substrate is 2-methyl-1,5-pentanediamine, and the piperidine derivative is 3-methylpiperidine.

[0021] The mesoporous material confined ruthenium catalyst provided by the present application successfully loads metal ruthenium in the pore channel of the mesoporous material, realizes the spatial confinement effect of metal particles, reduces the size of metal particles, improves the utilization rate of metal atoms, and thus improves the efficiency of the catalyst. Not only does it effectively overcome the problem of metal cluster dispersion in the traditional preparation method, but also provides a high-efficiency, sustainable and environmentally friendly catalytic system for the cyclization of diamines to synthesize piperidine derivatives. In the reaction of cyclization of diamines to synthesize piperidine derivatives, the catalyst exhibits the advantages of high conversion rate, high selectivity and high stability. The method not only reduces the generation of by-products and improves the yield of the reaction, but also has the advantages of mild reaction conditions and environmental friendliness, and has a broad application prospect in the field of organic synthesis. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1 Figure 2 is a transmission electron microscope image of the 2% Ru / SBA-15-500 catalyst obtained in Example 1 of the present application. DETAILED DESCRIPTION

[0023] In view of the deficiencies of the prior art, the inventors have successfully proposed the technical solutions of the present application after long-term research and a large number of practices. The technical solutions of the present application are clearly and completely described below. Obviously, the described embodiments are only a part of the present application, rather than all. Based on the embodiments in the present application, all other embodiments that can be obtained by those of ordinary skill in the art without creative efforts are within the protection scope of the present application.

[0024] The principles and features of the present application are described below, and the examples are only used to explain the present application, and not to limit the scope of the present application.

[0025] The experimental materials used in the following examples are commercially available from conventional biochemical reagent stores, unless otherwise specified. The loadings are all mass fractions (wt%).

[0026] Example 1

[0027] Preparation of Ru / SBA-15 catalyst by slow evaporation method

[0028] 0.013 g of solid ruthenium tricarbonyl (Ru3(CO) 12 ) powder was weighed and dissolved in 15 mL of acetone for ultrasonic treatment to prepare solution A; 300 mg of SBA-15 mesoporous molecular sieve solid powder was slowly and uniformly added to the solution A under stirring, and stirred at room temperature for 30 min at a rate of 1000 r min -1 , until there was no obvious solid precipitation in the mixture substrate, and then ultrasonic treatment was performed for 30 min; the obtained liquid mixture was slowly heated at 60℃ for 24 hours, and after being fully dried, the precursor of the ruthenium catalyst was obtained; after grinding treatment, the precursor was reduced at 500℃ for 2 hours under a 5% H2 / Ar (H2 and Ar mixed gas, the volume fraction of H2 being 5%) atmosphere, and finally the IM-2%Ru / SBA-15-500 catalyst (catalyst 1) was obtained. The same method was used to prepare IM-1%Ru / SBA-15-500 catalyst (catalyst 2, the amount of ruthenium tricarbonyl added was 0.007 g), IM-3%Ru / SBA-15-500 catalyst (catalyst 3, the amount of ruthenium tricarbonyl added was 0.020 g) with different loadings, and IM-2%Ru / SBA-15-200 catalyst (catalyst 4, reduction treatment temperature 200℃), IM-2%Ru / SBA-15-300 catalyst (catalyst 5, reduction treatment temperature 300℃), IM-2%Ru / SBA-15-400 catalyst (catalyst 6, reduction treatment temperature 400℃) with different reduction pretreatment temperatures. The transmission electron microscope image of the 2%Ru / SBA-15-500 catalyst (catalyst 1) is shown in Figure 1, it can be seen that the ruthenium nanoparticles are uniformly distributed in the channels of the mesoporous molecular sieve, and the average particle size is only 1.45 nm.

[0029] Comparative Example 1

[0030] Preparation of Ru / SBA-15 catalyst by rapid evaporation method

[0031] 0.013 g of solid powder of triruthenium dodecacarbonyl (Ru3(CO) 12 ) was weighed out, dissolved in 15 mL of acetone, and ultrasonically treated to prepare solution A; 300 mg of solid powder of SBA-15 mesoporous molecular sieve was slowly and uniformly added to the solution A under stirring, and stirred at room temperature for 30 min at a rate of 1000 r min -1 , until no obvious solid precipitate was present in the mixture substrate, and then ultrasonically treated for 30 min; the obtained liquid mixture was placed in a rotary evaporator, and acetone was evaporated therefrom under -0.8 MPa, 150 rpm, and 35°C to collect the mesoporous molecular sieve carrier impregnated with triruthenium dodecacarbonyl, which was then ground and subjected to reduction pretreatment under a 5% H2 / Ar atmosphere at 500°C for 2 hours to finally obtain a RE-2%Ru / SBA-15-500 catalyst (catalyst 7). The RE-2%Ru / SBA-15-200 catalyst (catalyst 8), the RE-2%Ru / SBA-15-300 catalyst (catalyst 9), and the RE-2%Ru / SBA-15-400 catalyst (catalyst 10) with different reduction pretreatment temperatures were prepared by the same method.

[0032] Comparative Example 2

[0033] Preparation of Ru / SiO2 catalyst by slow evaporation method

[0034] 0.013 g of solid powder of triruthenium dodecacarbonyl (Ru3(CO) 12 ) was weighed out, dissolved in 15 mL of acetone, and ultrasonically treated to prepare solution A; 300 mg of solid powder of SBA-15 mesoporous molecular sieve was slowly and uniformly added to the solution A under stirring, and stirred at room temperature for 30 min at a rate of 1000 r min -1The liquid mixture was slowly heated at 60 °C for 24 h until it was completely dried to obtain the precursor of the ruthenium catalyst. The precursor was ground and reduced at 500 °C for 2 h under 5% H2 / Ar atmosphere to obtain the 2% Ru / SiO2-500 catalyst (catalyst 11). The 2% Ru / SiO2-200 catalyst (catalyst 12), the 2% Ru / SiO2-300 catalyst (catalyst 13), and the 2% Ru / SiO2-400 catalyst (catalyst 14) were prepared by the same method with different reduction pretreatment temperatures.

[0035] Comparative Example 3

[0036] Ru / SBA-15 catalyst with RuCl3 as the ruthenium source

[0037] 0.013 g of ruthenium chloride (RuCl3) solid powder was weighed and dissolved in 15 mL of deionized water for ultrasonic treatment to obtain solution A. 300 mg of SBA-15 mesoporous molecular sieve solid powder was slowly and uniformly added to the solution A under stirring, and stirred at a constant temperature for 30 min at a rate of 1000 r / min -1 The liquid mixture was slowly heated at 60 °C for 24 h until it was completely dried to obtain the precursor of the ruthenium catalyst. The precursor was ground and reduced at 500 °C for 2 h under 5% H2 / Ar atmosphere to obtain the 2% Ru / SiO2-500 catalyst (catalyst 11). The 2% Ru / SiO2-200 catalyst (catalyst 12), the 2% Ru / SiO2-300 catalyst (catalyst 13), and the 2% Ru / SiO2-400 catalyst (catalyst 14) were prepared by the same method with different reduction pretreatment temperatures.

[0038] Comparative Example 4

[0039] Ru / SBA-15 catalyst with Ru(acac)3 as the ruthenium source

[0040] 0.024 g of acetylacetone (Ru(acac)3) solid powder was weighed and dissolved in 15 mL of acetone for ultrasonic treatment to obtain solution A. 300 mg of SBA-15 mesoporous molecular sieve solid powder was slowly and uniformly added to the solution A under stirring, and stirred at a constant temperature for 30 min at a rate of 1000 r / min -1, until there is no obvious solid precipitate in the mixture substrate, and then ultrasonic treatment is performed for 30 min; the obtained liquid mixture is slowly heated at 60℃ for 24 hours, and a precursor of a ruthenium catalyst is obtained after being fully dried; the precursor is ground, and reduction pretreatment is performed at 500℃ for 2 hours under a 5% H2 / Ar atmosphere, and finally, the 2% Ru / SBA-15 catalyst-500 (catalyst 16) is obtained.

[0041] Examples 2-7

[0042] 2 mmol of 2-methyl-1,5-pentanediamine and 1 mL of deionized water are added to a 25 mL batch autoclave, and 50 mg of the Ru / SBA-15 catalyst prepared in Example 1 is added. 1 MPa of H2 is filled, and reaction is performed at 130℃ for 8 h. After the reaction is completed, the reaction liquid is filtered, and the product 3-methylpiperidine is quantitatively analyzed by NMR and qualitatively analyzed by GC-MS.

[0043]

[0044] Comparative Examples 5-14

[0045] 2 mmol of 2-methyl-1,5-pentanediamine and 1 mL of deionized water are added to a 25 mL batch autoclave, and 50 mg of the ruthenium catalyst prepared in Comparative Examples 1-4 is added. 1 MPa of H2 is filled, and reaction is performed at 130℃ for 8 h. After the reaction is completed, the reaction liquid is filtered, and the product 3-methylpiperidine is quantitatively analyzed by NMR and qualitatively analyzed by GC-MS.

[0046] Product structure:

[0047]

[0048] In summary, the Ru / SBA-15 catalyst provided by the present application exhibits excellent performance under the confinement condition of mesoporous materials. By successfully loading the metal ruthenium into the pore channel of the SBA-15 mesoporous material, the spatial confinement effect of the metal particles is realized, the size of the metal particles is significantly reduced, the utilization rate of the metal atoms is improved, and thus the efficiency of the catalyst is improved.

[0049] In the reaction of synthesizing piperidine derivatives by cyclization of diamines, the catalyst of the present application exhibits excellent performance of high conversion rate, high selectivity and high stability. The catalyst not only effectively reduces the generation of by-products and improves the reaction yield, but also has mild reaction conditions, is environmentally friendly, and has a wide application prospect.

[0050] In summary, the Ru / SBA-15 catalyst provided by the application successfully overcomes some limitations of traditional catalysts under the limitation of mesoporous materials, and provides an efficient, sustainable and environmentally friendly catalytic system for the cyclization of diamines to synthesize piperidine derivatives.

[0051] The above merely describes preferred embodiments of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. The application of a mesoporous ruthenium catalyst confined in a material in the catalytic synthesis of piperidine derivatives via diamine cyclization, characterized in that: The diamine substrate is 2-methyl-1,5-pentanediamine, and the piperidine derivative is 3-methylpiperidine; the mesoporous material-confined ruthenium catalyst comprises a mesoporous material and metallic ruthenium supported in the pores of the mesoporous material; the loading of the active component ruthenium in the mesoporous material-confined ruthenium catalyst is 0.5–10 wt.%; the mesoporous material is a mesoporous molecular sieve; The method for preparing the mesoporous material-confined ruthenium catalyst includes the following steps: 1) Dissolve the ruthenium metal precursor in acetone and treat it with ultrasound to obtain solution A; the ruthenium metal precursor is dodecyltriruthenium; 2) Slowly and evenly add the mesoporous material solid powder to solution A which is under stirring, and stir vigorously at room temperature until there is no obvious solid precipitate in the mixture, and then perform ultrasonic treatment. 3) The mixture obtained by ultrasonic treatment is slowly heated at 55~65℃ for 20~25 hours, and after being fully dried, the precursor of ruthenium catalyst is obtained; 4) The precursor obtained in step 3) is ground and then reduced at 200~500℃ for 1~3 hours under a 5% H2 / Ar atmosphere to finally obtain a ruthenium catalyst confined in a mesoporous material.

2. The application according to claim 1, characterized in that: The diamine substrate 2-methyl-1,5-pentanediamine was subjected to a deamination cyclization reaction with a ruthenium catalyst confined in a mesoporous material under a hydrogen atmosphere at 50–200 °C and 0.1–3 MPa to obtain a piperidine derivative.

3. The application according to claim 2, characterized in that: Based on the Ru content, the molar amount of ruthenium catalyst confined by the mesoporous material is 0.025% to 2.5% of the molar amount of 2-methyl-1,5-pentanediamine.

4. The application according to claim 2, characterized in that: The deamination cyclization reaction time is 1~24 h.

5. The application according to claim 2, characterized in that: The deamination cyclization reaction is carried out in a solvent, which is one or more of water, cyclohexane, ethanol, tetrahydrofuran, and acetonitrile.

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