A cobalt-based crystalline catalyst with a three-dimensional porous structure, and a preparation method and application thereof

Abstract

The application discloses a three-dimensional porous structure cobalt-based crystalline catalyst and preparation and catalytic application thereof, the catalyst is a porous cobalt-based crystalline catalyst formed by mixing ligands of D-camphoric acid (D-cma) and 2,4,6-tris (4-pyridyl) -1,3,5-triazine (4-TPT) under a solvothermal condition, and mixing with cobalt nitrate hexahydrate Co (NO3) 3.6H2O; the application provides a preparation method of the catalyst, the mixed ligand and cobalt nitrate are mixed, then are transferred into a hydrothermal kettle to perform a solvothermal reaction, and the Co (II) -based crystalline material is separated by extraction filtration, washing and drying; the crystalline material has a large specific surface area and a large conjugated system, has high catalytic activity on an oxidation alkylation reaction of styrene, and the highest separation yield can reach 88%.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of cobalt-based crystalline catalysts, and particularly relates to a cobalt-based crystalline catalyst with a three-dimensional porous structure and a preparation method and application thereof. BACKGROUND

[0002] The difunctionalization reaction of olefins is an important research direction in organic chemistry, which increases the diversity and function of organic compounds by introducing two functional groups, and provides the required raw materials for new drug development, material manufacturing and polymer synthesis. Among them, oxidative alkylation is a common way of olefin difunctionalization, which can convert olefins into difunctional compounds containing carbonyl and alkyl groups in one step, simplifying the synthesis process and improving the structural accuracy of the product. Carbonyl, as an important functional group, has wide application in the fields of drugs and materials, and becomes a key element for new drug design and high-performance material preparation. However, traditional oxidative alkylation methods have strict reaction conditions, low yield, and many by-products, which limit their wide application. Therefore, developing an efficient, environmentally friendly, and mild olefin oxidative alkylation method is of great significance to promote the development of organic chemistry and meet the needs of new drugs and new materials.

[0003] In patent CN 116969820A, a method for olefin difunctionalization using 1,4-alkyne compound, trifluoromethyl source, base and solvent is disclosed. The method has mild conditions, but the process steps are complicated and the reaction time is long, which limits its application in catalytic reactions. In patent CN 117903071 A, alpha-methyl styrene derivatives, azole derivatives, photocatalysts and inorganic bases are used to obtain alpha-amino ketone derivatives under visible light irradiation. The method has mild conditions and fast reaction time, but the yield is generally between 50-60%, which limits its application in catalytic reactions.

[0004] How to solve the problems of small specific surface area, complicated preparation, low catalytic efficiency, and few active sites in traditional methods has become an urgent problem to be solved. SUMMARY

[0005] This section aims to summarize some aspects of the embodiments of the present application and briefly introduce some preferred embodiments. Some simplifications or omissions may be made in this section and the abstract and title of the specification to avoid obscuring the purpose of this section, abstract and title, and such simplifications or omissions cannot be used to limit the scope of the present application.

[0006] In view of the above and / or problems existing in the prior art, the present application is proposed.

[0007] Therefore, the purpose of the present application is to overcome the deficiencies in the prior art and provide a cobalt-based crystalline catalyst.

[0008] To solve the above technical problems, the present application provides the following technical solutions: a cobalt-based crystalline catalyst is provided, the Co(II)-based crystalline catalyst is assembled from a mixed ligand and Co(II), wherein the mixed ligand is composed of 2,4,6-tris(4-pyridyl)-1,3,5-triazine and D-camphoric acid, and the Co(II) is a central ion.

[0009] Another object of the present application is to overcome the deficiencies in the prior art and provide a preparation method of a cobalt-based crystalline catalyst.

[0010] As a preferred embodiment of the preparation method of the present application, the preparation method comprises the following steps:

[0011] 2,4,6-tris(4-pyridyl)-1,3,5-triazine and D-camphoric acid are mixed to form a mixed ligand;

[0012] The mixed ligand is mixed with cobalt nitrate hydrate in a solvent under ultrasonic or stirring to configure a precursor solution;

[0013] The precursor solution is transferred into an autoclave, and a solvothermal reaction is carried out at 80-120°C, and then the Co(II)-based crystalline catalyst is obtained by filtration, washing and drying.

[0014] As a preferred embodiment of the preparation method of the present application, the molar ratio of 2,4,6-tris(4-pyridyl)-1,3,5-triazine to D-camphoric acid is 1:1-1:2.

[0015] As a preferred embodiment of the preparation method of the present application, the molar ratio of the cobalt nitrate hydrate (Co(NO3)2·6H2O) to 2,4,6-tris(4-pyridyl)-1,3,5-triazine is 1:1-3:1.

[0016] As a preferred embodiment of the preparation method of the present application, the solvent is a mixed solvent of N,N-dimethylformamide and ethanol.

[0017] As a preferred embodiment of the preparation method of the present application, the volume ratio of N,N-dimethylformamide to ethanol is 1:1-3:1.

[0018] As a preferred embodiment of the preparation method of the present application, the solvothermal reaction time is 24-96 hours.

[0019] Another object of the present application is to overcome the deficiencies in the prior art and provide the application of the cobalt-based crystalline catalyst in catalyzing the preparation of acetophenone-based compounds.

[0020] The present application has the following beneficial effects:

[0021] 1. The Co(II) based crystalline material obtained by the present application has a large specific surface area, empty active sites, high catalytic activity, and especially high catalytic efficiency for the oxidative alkylation reaction of styrene, and the catalyst can be recycled without loss of its skeletal integrity and catalytic activity.

[0022] 2. The present application catalyzes the oxidative alkylation reaction of styrene and tetrahydrofuran, and the highest separation yield can reach 88%, such material has high structural stability and good recycling effect, and the catalytic efficiency is still as high as 85% after 10 cycles.

[0023] 3. The synthesis process of the present application is simple, and the controllable assembly of the catalyst material can be realized, which has good selectivity and yield.

[0024] 4. The Co(II) based porous crystalline catalyst material synthesized by the present application can solve the problems of small specific surface area, complicated preparation, low catalytic efficiency, and few active sites of traditional catalysts, and when used for catalyzing the oxidative alkylation reaction of styrene, the catalyst has high yield and good stability, which will greatly promote the application prospect of phenone product synthesis. BRIEF DESCRIPTION OF DRAWINGS

[0025] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings needed in the embodiment description will be briefly introduced below, and obviously, the drawings in the following description are only some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor. Among them:

[0026] Figure 1 It is a two-dimensional structure diagram of the Co(II) porous crystalline catalyst in embodiment 1 of the present application.

[0027] Figure 2 It is a single crystal three-dimensional structure diagram of the Co(II) porous crystalline catalyst in embodiment 1 of the present application.

[0028] Figure 3 It is the N2 adsorption-desorption curve diagram of the crystalline catalyst in embodiment 1 of the present application.

[0029] Figure 4 It is the HNMR spectrum diagram of the separated product in embodiment 6 of the present application. 1 HNMR spectrum diagram. DETAILED DESCRIPTION

[0030] In order to make the above-mentioned purposes, features and advantages of the present application more obvious and easy to understand, the specific embodiments of the present application will be described in detail below.

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details set forth in this description. In other instances, well-known methods have not been described in detail in order not to unnecessarily obscure aspects of the present application.

[0032] Second, the term "one embodiment" or "an embodiment" as used herein means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one implementation of the present application. The appearances of the phrase "in one embodiment" or "in an embodiment" in various places in the specification are not necessarily all referring to the same embodiment, nor are the various embodiments necessarily mutually exclusive.

[0033] The raw materials and reagents used in the present application are commercially available unless otherwise specified.

[0034] Example 1 Synthesis of Co(II) porous crystalline catalyst

[0035] (1) 2,4,6-tris(4-pyridyl)-1,3,5-triazine and D-camphoric acid were weighed according to the molar ratio of 1:1, mixed, and then a mixed ligand was prepared;

[0036] (2) Cobalt nitrate hydrate was weighed according to the molar ratio of 1:1 of 2,4,6-tris(4-pyridyl)-1,3,5-triazine in (1);

[0037] (3) The cobalt nitrate hydrate and the mixed ligand were mixed in a mixed solvent of DMF / EtOH (volume ratio of 4:2) under ultrasonic or stirring to prepare a precursor solution;

[0038] (4) The precursor solution was transferred into a hydrothermal kettle, and a solvothermal reaction was carried out at 80°C for 48 hours. After filtration, washing, and drying, a Co(II)-based crystalline catalyst was obtained.

[0039] The obtained Co(II)-based crystalline catalyst is composed of a mixed ligand of 2,4,6-tris(4-pyridyl)-1,3,5-triazine and D-camphoric acid, and Co(II) as a central ion. The mixed ligand and Co(II) assemble to form a three-dimensional porous crystalline catalyst with a tetragonal pyramid structure.

[0040] The coordination structure of the catalyst was obtained by collecting diffraction intensity data on a Bruker APEX II diffractometer. In the material, the Co(II) central ion is connected to the carboxyl oxygen atoms from four D-camphoric acids and a pyridine nitrogen atom from 2,4,6-tris(4-pyridyl)-1,3,5-triazine, respectively, to form a five-coordinated tetragonal pyramid structure, as shown in Figure 1As shown, the two symmetry-related Co(II) centers are bridged by four carboxyl groups to form a stable Co2(OCO)4 binuclear paddle-wheel unit, which is connected by D-camphoric acid to form a two-dimensional layered structure, which is further connected by 4-TPT to form a porous material with a three-dimensional structure, such as Figure 2 As shown, two of the three pyridines of 2,4,6-tris(4-pyridyl)-1,3,5-triazine are involved in the construction of the structure, and the remaining one pyridine nitrogen atom containing a lone pair of electrons is not involved in coordination and extends to the center of the channel, so it can well contact the guest molecules as a Lewis base catalytic center; at the same time, the Co(II) center therein acts as a Lewis acid to further catalyze the oxidative alkylation reaction.

[0041] Figure 3 The N2 adsorption-desorption isotherm curve of the sample obtained in Example 1 is disclosed, and experimental tests show that the obtained porous material has a large specific surface area, and its S BET = 856.4 m 2 / g.

[0042] Example 2

[0043] The difference between this example and Example 1 is that in step (4) of this example, the solvothermal reaction is carried out at a temperature of 100°C for 48 hours, and the other steps are the same.

[0044] Example 3

[0045] The difference between this example and Example 1 is that in step (2) of this example, the hydrated cobalt nitrate metal salt is weighed according to a molar ratio of 2:1 of hydrated cobalt nitrate to 2,4,6-tris(4-pyridyl)-1,3,5-triazine in (1), and in step (4) of this example, the solvothermal reaction is carried out at a temperature of 100°C for 96 hours, and the other steps are the same.

[0046] Example 4

[0047] The difference between this example and Example 1 is that in step (2) of this example, the hydrated cobalt nitrate metal salt is weighed according to a molar ratio of 3:1 of hydrated cobalt nitrate to 2,4,6-tris(4-pyridyl)-1,3,5-triazine in (1), and in step (4) of this example, the solvothermal reaction is carried out at a temperature of 120°C for 24 hours, and the other steps are the same.

[0048] Example 5

[0049] The difference between this example and Example 1 is that in step (1) of this example, 2,4,6-tris(4-pyridyl)-1,3,5-triazine is weighed according to a molar ratio of 1:2 to D-camphoric acid, and the other steps are the same.

[0050] Example 6 Reaction of catalytic oxidative alkylation of styrene with tetrahydrofuran to prepare acetophenone

[0051] In the reaction of catalytic oxidative alkylation of styrene with tetrahydrofuran, styrene (2 mmol) and tetrahydrofuran (20 mL) were used as the reaction substrates, N-hydroxyphthalimide (NHPI, 20 mol%) was added as the initiator, and 10 wt% of the Co(II)-based crystalline catalyst was added to a round-bottom flask, and an oxygen balloon was used to provide an oxygen atmosphere.

[0052] The reaction mixture was heated and stirred on an oil bath at 65°C for 12 hours, and after the reaction was completed, it was allowed to cool to room temperature naturally.

[0053] The reaction mixture was poured into a sand core funnel pre-loaded with diatomite for filtration treatment, and ethyl acetate was used as the washing solvent to wash the filter cake thoroughly.

[0054] Subsequently, the collected filtrate was distilled under reduced pressure to remove the solvent and obtain the crude product. To obtain the target product with high purity, the crude product was further subjected to column chromatography separation treatment, and petroleum ether: ethyl acetate with a volume ratio of 20:1 was used as the eluent, the product was collected, the solvent was removed under reduced pressure on a rotary evaporator, the product was dried and weighed to calculate the yield, and the product was provided for further nuclear magnetic testing, as shown in Figure 4 .

[0055] After the above reaction was completed, the catalyst could be separated by simple filtration, washed, and used in the next round of catalyst recycling experiments, and the specific reaction steps were the same as above. The catalytic conversion efficiency was still above 85% after 10 or more cycles.

[0056] Example 7

[0057] The catalytic efficiency of the catalyst for the oxidative alkylation of styrene containing different substituents was shown by the following reaction equation:

[0058]

[0059] The experimental results are shown in Table 1 (where R represents a substituent), and the results show that the catalyst has high catalytic efficiency for the oxidative alkylation of styrene with different substituents.

[0060] Table 1

[0061]

[0062]

[0063] It should be noted that the above examples are only used to illustrate the technical solutions of the present application but not limit the present application. Although the present application is described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solutions of the present application can be modified or equivalently replaced, without departing from the spirit and scope of the technical solutions of the present application, which should be covered in the scope of the claims of the present application.

Claims

1. A cobalt-based crystalline catalyst characterized by: The Co(II)-based crystalline catalyst is assembled by a mixed ligand and Co(II), wherein the mixed ligand is composed of 2, 4, 6-tris(4-pyridyl)-1, 3, 5-triazine and D-camphoric acid, and the Co(II) is a central ion.

2. The method of making a cobalt-based crystalline catalyst of claim 1, characterized by: The application relates to a Co(II)-based crystalline catalyst and a preparation method thereof. 2, 4, 6-tris(4-pyridyl)-1, 3, 5-triazine and D-camphoric acid are mixed to form a mixed ligand; Cobalt nitrate hydrate and the mixed ligand are mixed in a solvent under ultrasonic or stirring to configure a precursor solution; The precursor solution is transferred into an autoclave, and a solvothermal reaction is carried out at 80-120 DEG C, and then the Co(II)-based crystalline catalyst is obtained through filtration, washing and drying.

3. The production method according to claim 2, characterized by: The molar ratio of 2, 4, 6-tris(4-pyridyl)-1, 3, 5-triazine to D-camphoric acid is 1:1-1:

2.

4. The production method according to claim 2, characterized by: The molar ratio of cobalt nitrate hydrate to 2, 4, 6-tris(4-pyridyl)-1, 3, 5-triazine is 1:1-3:

1.

5. The production method according to claim 2, wherein: The solvent is a mixed solvent of N,N-dimethylformamide and ethanol.

6. The production method according to claim 5, characterized by: The volume ratio of N,N-dimethylformamide to ethanol is 1:1-3:

1.

7. The production method according to claim 2, wherein: The solvothermal reaction time is 24-96h.

8. The Co(II)-based crystalline catalyst according to claim 1 is applied to catalytic preparation of acetophenone-based compounds.

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