A method for the reductive amination of furfural with o-nitroaniline to synthesize 1,2-disubstituted benzimidazoles

Abstract

This invention proposes a method for the reductive amination of furfural with o-nitroaniline to synthesize 1,2-disubstituted benzimidazole, belonging to the field of biomass fine chemical technology. The method utilizes rare-earth phosphate-supported nickel phosphide as a catalyst. The catalyst comprises rare-earth phosphate and nickel phosphide supported on the rare-earth phosphate, with the nickel phosphide comprising 10% by mass. An ethanol solution of furfural and o-nitroaniline is reacted with the nickel phosphide catalyst in a sealed container at a pressure of 0.5 MPa under a hydrogen atmosphere to obtain 1,2-disubstituted benzimidazole. This invention uses ethanol as the green solvent as the reaction phase, achieving the preparation of 1,2-disubstituted benzimidazole under relatively mild conditions.

Description

Technical Field

[0001] This invention belongs to the field of biomass fine chemical technology, and particularly relates to a method for synthesizing 1,2-disubstituted benzimidazole by reducing furfural with o-nitroaniline. Background Technology

[0002] 1,2-Disubstituted benzimidazoles are important chemical raw materials with a wide range of applications. Benzimidazoles are often used as intermediates in bactericidal and disinfectant drugs; for example, 2-(2-furanyl)-benzimidazole is an important bactericidal pesticide. 2-(furan-2-yl)-3H-benzimidazole-5-carboxylic acid and 2-(furan-2-yl)-3H-benzimidazole-5-amine have bactericidal and anti-inflammatory effects and good biological activity, making them suitable for the development of new drugs. However, existing synthetic methods for benzimidazoles mostly employ homogeneous catalytic systems, which suffer from complex reaction separation processes, the use of expensive amides and haloaniline derivatives, complex and expensive solvent compositions, the need for external acid and alkali additions that corrode the equipment, and poor catalyst recovery. Xie et al. used copper iodide (CuI) and K3PO4 as catalysts, with substituted 2-haloanilines and benzamides as starting materials, and utilized copper-catalyzed Ullmann-type coupling reactions and intramolecular nucleophilic addition processes to obtain products with various substituents in moderate to excellent yields, showing potential applications in the synthesis of biological and pharmaceutical compounds. Arya et al. formed 1,2-disubstituted benzimazoles with similar substituents in excellent yields by reacting o-phenylenediamine derivatives with different aldehydes in the presence of sodium fluoride (NaF) in glacial acetic acid. In response, this invention attempts to utilize more inexpensive o-nitroaniline compounds and aromatic aldehydes, using inexpensive and environmentally friendly ethanol as a solvent (without added acids or bases), under mild neutral conditions to achieve efficient conversion of 1,2-disubstituted benzimazoles. Summary of the Invention

[0003] To address the aforementioned technical problems, this invention proposes a method for the reductive amination of furfural and o-nitroaniline to synthesize 1,2-disubstituted benzimidazole. This invention uses inexpensive and stable rare earth phosphate-supported nickel phosphide as a catalyst and green solvent ethanol as the reaction phase. Under relatively mild conditions, furfural and o-nitroaniline are directly converted to 1,2-disubstituted benzimidazole in a maximum yield of 80.6%.

[0004] To achieve the above objectives, the present invention provides the following technical solution: One of the technical solutions of the present invention: A rare earth phosphate supported nickel phosphide catalyst (Ni2P / REPO4 catalyst, RE representing rare earth element) comprises a rare earth phosphate (REPO4) and nickel phosphide (Ni2P) supported on the rare earth phosphate, wherein the mass fraction of nickel phosphide in the rare earth phosphate supported nickel phosphide catalyst is 10%. The rare earth elements in the rare earth phosphate include one or more of La, Ce, Pr, Sm, Gd, Dy, and Y.

[0005] The second technical solution of the present invention: A method for preparing the rare earth phosphate-supported nickel phosphide catalyst (Ni2P / REPO4 catalyst) includes the following steps: Rare earth phosphates and nickel salts were mixed and dispersed in water, and diammonium hydrogen phosphate solution was added. The mixed suspension was heated and reacted, followed by calcination and thermal reduction to obtain the rare earth phosphate-supported nickel phosphide catalyst.

[0006] Furthermore, the heating reaction temperature is 100℃~120℃, and the reaction time is 8~14h; The calcination process was carried out in air at a temperature of 600°C for 4 hours. The thermal reduction treatment was carried out in an inert gas atmosphere at a temperature of 600°C for 2 hours.

[0007] Furthermore, the preparation method of the rare earth phosphate (REPO4) includes the following steps: Prepare a 0.1–0.2 mol / L rare earth nitrate solution and place it in a stirrer. Add a 0.1–0.2 mol / L ammonium hydrogen phosphate ((NH4)2HPO4) solution dropwise until no more precipitate forms. Continue stirring for 1 hour and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180–200 °C for 12–24 hours. After the reaction is complete, centrifuge to filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 hours to obtain the REPO4 sample.

[0008] The third technical solution of the present invention: A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural and o-nitroaniline, using the rare earth phosphate-supported nickel phosphide catalyst as a catalyst to catalyze the synthesis of 1,2-disubstituted benzimidazole from furfural and o-nitroaniline.

[0009] Furthermore, it includes the following steps: An ethanol solution of furfural and o-nitroaniline was placed in a sealed container with the rare earth phosphate-supported nickel phosphide catalyst and reacted in a hydrogen atmosphere to prepare 1,2-disubstituted benzimidazole.

[0010] Furthermore, the pressure inside the sealed container is 0.5 MPa.

[0011] Furthermore, the concentrations of furfural and o-nitroaniline in the ethanol solution of furfural and o-nitroaniline are 0.1 mol / L and 0.05 mol / L, respectively.

[0012] Furthermore, the volume-to-mass ratio of the furfural and o-nitroaniline ethanol solution to the rare earth phosphate-supported nickel phosphide catalyst is 1 mL: 2.5 mg.

[0013] Furthermore, the reaction temperature is 90°C and the reaction time is 8 hours.

[0014] Compared with the prior art, the present invention has the following advantages and technical effects: (1) The main function of nickel phosphide (Ni2P) is to activate furfural and o-nitroaniline. However, due to its weak activation ability for hydrogen and few acid-base sites, its catalytic efficiency is very low. In the usual synthesis process, Ni2P particles are large and have low dispersion, making it difficult to form a strong catalytic interface with other components. Although rare earth phosphates (REPO4) have a strong activation ability for hydrogen, different rare earth phosphates have different hydrogen activation abilities and surface acid-base sites. In this regard, the present invention uses a two-component composite phosphate as a support to combine REPO4 with Ni2P, and improves the composite interface of Ni2P and REPO4 to obtain Ni2P with higher dispersion. The results show that the catalyst of the present invention has excellent performance in the aqueous hydrogenation conversion of furfural and o-nitroaniline to 1,2-disubstituted benzimidazole.

[0015] (2) In this invention, inexpensive and stable rare earth phosphate supported nickel phosphide is used as catalyst and green solvent ethanol is used as reaction phase. Under relatively mild conditions, furfural and o-nitroaniline are directly converted into 1,2-disubstituted benzimidazole with a maximum yield of 80.6%.

[0016] (3) Compared with the prior art, the method for converting furfural and o-nitroaniline into 1,2-disubstituted benzimidazole provided by the present invention has low raw material and catalyst costs, green and mild reaction conditions, easy operation conditions, and high yield of the target product 1,2-disubstituted benzimidazole. This process system is expected to innovate and replace the existing 1,2-disubstituted benzimidazole production process, and has great potential for large-scale application. It is worth promoting. Attached Figure Description

[0017] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1This is the reaction equation for the synthesis of 1,2-disubstituted benzimidazole by the reductive amination of furfural and o-nitroaniline in this invention; Figure 2 The XRD patterns of the 10% Ni2P / REPO4 catalysts prepared in Examples 1-7 are shown below. Figure 3 The images shown are SEM images of the catalysts prepared in Examples 1-7 of this invention, where A represents Example 1, B represents Example 2, C represents Example 3, D represents Example 4, E represents Example 5, F represents Example 6, and G represents Example 7. Detailed Implementation

[0018] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as a limitation of the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0019] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Every smaller range between any stated value or intermediate value within a stated range, and any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0020] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0021] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0022] The terms “include,” “including,” “have,” “contain,” etc., used in this article are all open-ended terms, meaning that they include but are not limited to.

[0023] This invention provides a rare earth phosphate supported nickel phosphide catalyst (Ni2P / REPO4 catalyst, RE represents rare earth element), comprising rare earth phosphate (REPO4) and nickel phosphide (Ni2P) supported on rare earth phosphate, wherein the mass fraction of nickel phosphide in the rare earth phosphate supported nickel phosphide catalyst is 10%. Rare earth elements in rare earth phosphates include one or more of La, Ce, Pr, Sm, Gd, Dy, and Y.

[0024] This invention also proposes a method for preparing the above-mentioned rare earth phosphate supported nickel phosphide catalyst (Ni2P / REPO4 catalyst), comprising the following steps: Rare earth phosphates and nickel salts were mixed and dispersed in water, and diammonium hydrogen phosphate solution was added. The mixed suspension was heated and reacted, followed by calcination and thermal reduction to obtain rare earth phosphate-supported nickel phosphide catalyst.

[0025] In a preferred embodiment of the present invention, the mass ratio of rare earth phosphate to nickel salt is 0.3:(0.1-0.3), and the amount of diammonium hydrogen phosphate solution added needs to be excessive. The purpose is to ensure that Ni species are fully deposited and precipitated on the CePO4 sample. For example, in the process of preparing Ni2P / CePO4 catalyst, when the amount of rare earth phosphate (CePO4) is 0.3g and the amount of nickel salt (Ni(NO3)2·6H2O) is 0.1170g, the amount of diammonium hydrogen phosphate solution added should be 0.054g. However, in order to promote the full deposition and precipitation of Ni species on the CePO4 sample, the amount of diammonium hydrogen phosphate solution added can be increased to greater than 0.060g to meet the requirement that the mass fraction of Ni2P in the catalyst is 10%.

[0026] In a preferred embodiment of the present invention, the temperature of the heating reaction is 100℃~120℃, and the reaction time is 8~14h.

[0027] In a preferred embodiment of the present invention, the calcination process is carried out in air at a temperature of 600°C for 4 hours.

[0028] In a preferred embodiment of the present invention, the thermal reduction treatment is carried out in an inert gas atmosphere at a temperature of 600°C for 2 hours.

[0029] In a preferred embodiment of the present invention, the method for preparing rare earth phosphate (REPO4) includes the following steps: Prepare a 0.1–0.2 mol / L (preferably 0.1 mol / L) rare earth nitrate solution and place it in a stirrer. Add a 0.1–0.2 mol / L (preferably 0.1 mol / L) monoammonium phosphate ((NH4)2HPO4) solution dropwise until no more precipitate forms. Continue stirring for 1 hour, then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor and react at 180–200°C for 12–24 hours (preferably 12 hours at 180°C). After the reaction, centrifuge to filter out the solid, wash it, dry it overnight at 70°C, and then calcine it in air at 600°C for 4 hours to obtain the REPO4 sample.

[0030] This invention also proposes a method for the reductive amination of furfural with o-nitroaniline to synthesize 1,2-disubstituted benzimidazole, using the above-mentioned rare earth phosphate supported nickel phosphide catalyst as a catalyst to catalyze the synthesis of 1,2-disubstituted benzimidazole from furfural with o-nitroaniline, comprising the following steps: 1,2-Disubstituted benzimidazole was prepared by reacting an ethanol solution of furfural and o-nitroaniline with a rare earth phosphate-supported nickel phosphide catalyst in a sealed container under a hydrogen atmosphere.

[0031] In a preferred embodiment of the present invention, the pressure in the sealed container is 0.5 MPa.

[0032] In a preferred embodiment of the present invention, the concentrations of furfural and o-nitroaniline in the ethanol solution of furfural and o-nitroaniline are 0.1 mol / L and 0.05 mol / L, respectively.

[0033] In a preferred embodiment of the present invention, the volume-to-mass ratio of the ethanol solution of furfural and o-nitroaniline to the rare earth phosphate-supported nickel phosphide catalyst is 1 mL: 2.5 mg.

[0034] In a preferred embodiment of the present invention, the reaction temperature is 90°C and the reaction time is 8 hours.

[0035] The reaction equation for the synthesis of 1,2-disubstituted benzimidazole by the reductive amination of furfural and o-nitroaniline in this invention is shown below. Figure 1 .

[0036] In this embodiment of the invention, atmospheric pressure refers to standard atmospheric pressure, which has a value of 101325 Pascals (Pa).

[0037] The technical solution of the present invention will be further illustrated by the following embodiments.

[0038] Example 1 A method for preparing a rare earth phosphate-supported nickel phosphide catalyst (Ni2P / CePO4 catalyst) includes the following steps: (1) Prepare 30 mL of 0.1 mol / L Ce(NO3)3·6H2O solution, place it in a stirrer, and add 30 mL of 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate is formed. Continue stirring for 1 h, then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor and react at 180 °C for 12 h. After the reaction is completed, centrifuge and filter out the solid, wash it, dry it at 70 °C overnight, and calcine it in air at 600 °C for 4 h to obtain CePO4 sample. (2) Weigh 0.3g of CePO4 sample obtained in step (1) and disperse it in 40mL of water. Disperse 0.1170g of Ni(NO3)2·6H2O in 10mL of water. Mix the two and stir. Add excess (0.06g) of diammonium hydrogen phosphate solution (0.05mol / L) to allow Ni species to fully precipitate on the CePO4 sample. Transfer the resulting mixed suspension to an oven and react at 120℃ for 12h. Then calcine at 600℃ in air for 4h. Then perform thermal reduction treatment at 600℃ for 2h to obtain Ni2P / CePO4 catalyst. The mass fraction of Ni2P in the catalyst is 10%, which is recorded as 10% Ni2P / CePO4 (meaning that the mass percentage of Ni2P relative to the overall catalyst is 10%, and the same applies below).

[0039] Example 2 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / La) 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and La(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction, centrifuge and filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain La. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of La obtained in step (1). 0.5 Ce 0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow Ni species to fully precipitate on the La. 0.5 Ce 0.5The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined in air at 600°C for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / La. 0.5 Ce 0.5 PO4 catalyst, the mass fraction of Ni2P in the catalyst is 10%, denoted as 10% Ni2P / La 0.5 Ce 0.5 PO4.

[0040] Example 3 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / Pr) 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and Pr(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction is complete, centrifuge to filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain Pr. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of Pr obtained in step (1). 0.5 Ce 0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow the Ni species to fully precipitate on the Pr. 0.5 Ce 0.5 The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined at 600°C in air for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / Pr. 0.5 Ce 0.5 PO4 catalyst, the mass fraction of Ni2P in the catalyst is 10%, denoted as 10%Ni2P / Pr 0.5 Ce 0.5 PO4.

[0041] Example 4 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / Sm) 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and Sm(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction is complete, centrifuge to filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain Sm. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of the Sm obtained in step (1). 0.5 Ce 0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow the Ni species to fully precipitate on the Sm. 0.5 Ce 0.5 The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined in air at 600°C for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / Sm. 0.5 Ce 0.5 PO4 catalyst, the mass fraction of Ni2P in the catalyst is 10%, denoted as 10%Ni2P / Sm 0.5 Ce 0.5 PO4.

[0042] Example 5 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / Gd) 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and Gd(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction is complete, centrifuge and filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain Gd. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of the Gd obtained in step (1). 0.5 Ce0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow the Ni species to fully precipitate on the Gd. 0.5 Ce 0.5 The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined in air at 600°C for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / Gd. 0.5 Ce 0.5 A PO4 catalyst with a Ni2P mass fraction of 10% is denoted as 10% Ni2P / Gd. 0.5 Ce 0.5 PO4.

[0043] Example 6 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / Dy 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and Dy(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction is complete, centrifuge to filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain Dy. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of the Dy obtained in step (1). 0.5 Ce 0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow the Ni species to fully precipitate on the Dy. 0.5 Ce 0.5 The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined in air at 600°C for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / Dy. 0.5 Ce 0.5 A PO4 catalyst with a Ni2P mass fraction of 10% is denoted as 10% Ni2P / Dy.0.5 Ce 0.5 PO4.

[0044] Example 7 A rare earth phosphate supported nickel phosphide catalyst (Ni2P / Y) 0.5 Ce 0.5 The preparation method of PO4 catalyst includes the following steps: (1) Prepare 15 mL each of Ce(NO3)3·6H2O and Y(NO3)3·6H2O solutions with a concentration of 0.1 mol / L. Mix the two solutions in a stirrer and add 30 mL of a 0.1 mol / L (NH4)2HPO4 solution dropwise until no more precipitate forms. Continue stirring for 1 h and then transfer the mixture to a polytetrafluoroethylene hydrothermal reactor. React at 180 °C for 12 h. After the reaction is complete, centrifuge to filter out the solid, wash it, dry it overnight at 70 °C, and then calcine it in air at 600 °C for 4 h to obtain Y. 0.5 Ce 0.5 PO4 sample; (2) Weigh 0.3g of Y obtained in step (1). 0.5 Ce 0.5 The PO4 sample was dispersed in 40 mL of water, and 0.1170 g of Ni(NO3)2·6H2O was dispersed in 10 mL of water. After mixing and stirring, excess (0.06 g) of diammonium hydrogen phosphate solution (0.05 mol / L) was added to allow the Ni species to fully precipitate on the Y. 0.5 Ce 0.5 The resulting mixed suspension was transferred to an oven and reacted at 120°C for 12 hours on a PO4 sample. It was then calcined in air at 600°C for 4 hours, followed by a thermal reduction treatment at 600°C for 2 hours to obtain Ni2P / Y. 0.5 Ce 0.5 A PO4 catalyst with a Ni2P mass fraction of 10% is denoted as 10%Ni2P / Y. 0.5 Ce 0.5 PO4.

[0045] The XRD patterns of the 10% Ni2P / REPO4 catalysts prepared in Examples 1-7 are shown in [reference needed]. Figure 2 .from Figure 2 As can be seen from the XRD pattern, the peaks with diffraction angles of 40.80°, 44.80°, 47.44°, and 54.20° in the sample belong to the Ni2P phase (corresponding to PDF card #03-0953). Furthermore, the characteristic diffraction peaks of rare earth phosphate monoclinic or hexagonal crystal form are clearly visible in the XRD pattern, indicating that the 10% Ni2P / REPO4 catalyst is composed of two phases, Ni2P and REPO4.

[0046] SEM images of the catalysts prepared in Examples 1-7 of this invention are shown below. Figure 3 Where A is Example 1, B is Example 2, C is Example 3, D is Example 4, E is Example 5, F is Example 6, and G is Example 7. From Figure 3 As can be seen, the spherical Ni2P is tightly attached to the surface of the rod-shaped rare earth phosphate, indicating that the Ni2P / REPO4 supported catalyst was successfully prepared.

[0047] The catalysts prepared in Examples 1-7 were used for the reductive amination of furfural with o-nitroaniline to synthesize 1,2-disubstituted benzimidazole, as detailed in the following examples: Example 8 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add 50 mg of the 10% Ni2P / CePO4 catalyst prepared in Example 1 and stir at 350 rpm to mix evenly. Then seal the reactor and purge it with H2 (hydrogen) at atmospheric pressure 5 times. Then purge with H2 to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, raise the reaction temperature to 90 °C and maintain the stirring speed at 350 rpm. After the reaction is completed in 8 h, cool to room temperature and perform GC quantitative analysis on the product. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0048] Example 9 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) was placed in a 50 mL pressure reaction vessel, and then 10% Ni2P / La prepared in Example 2 was added. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0049] Example 10 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / Pr solution prepared in Example 3. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0050] Example 11 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / Sm solution prepared in Example 4. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0051] Example 12 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / Gd solution prepared in Example 5. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0052] Example 13 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / Dy solution prepared in Example 6. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0053] Example 14 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / Y solution prepared in Example 7. 0.5 Ce 0.5 50 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 0.5 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0054] Example 15 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2Pla solution prepared in Example 2. 0.5 Ce 0.5250 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 2.0 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 8 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0055] Example 16 A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline includes the following steps: Take 20 mL of an ethanol solution of furfural (0.1 mol / L) and o-nitroaniline (0.05 mol / L) and place it in a 50 mL pressure reaction vessel. Add the 10% Ni2P / La solution prepared in Example 2. 0.5 Ce 0.5 250 mg of PO4 catalyst was mixed evenly with stirring at 350 rpm. The reactor was then sealed and purged with H2 at atmospheric pressure five times. H2 was then added again to adjust and maintain the internal pressure of the reactor at 2.0 MPa. After sealing the gas path, the reaction temperature was raised to 90 °C and the stirring speed was maintained at 350 rpm. The reaction was stopped after 16 h and cooled to room temperature. The product was quantitatively analyzed by GC. The conversion rate of o-nitroaniline and the yield of 1,2-disubstituted benzimidazole are shown in Table 1.

[0056] Table 1. Yield and conversion rate results in Examples 8-16 As can be seen from Table 1, the synthesis process of Examples 8-16 of the present invention can hydrogenate furfural and o-nitroaniline to 1,2-disubstituted benzimidazole in aqueous solution under relatively mild conditions, and the yield is high. The highest yield of 1,2-disubstituted benzimidazole is achieved under the conditions of Examples 9, 15, and 16, reaching more than 80%. This indicates that the method of synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural and o-nitroaniline of the present invention has great potential for industrial application.

[0057] The above are merely preferred embodiments of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A rare earth phosphate-supported nickel phosphide catalyst, characterized in that, It includes rare earth phosphates and nickel phosphide supported on the rare earth phosphates, wherein the nickel phosphide mass fraction in the rare earth phosphate-supported nickel phosphide catalyst is 10%. The rare earth elements in the rare earth phosphate include one or more of La, Ce, Pr, Sm, Gd, Dy, and Y.

2. A method for preparing the rare earth phosphate-supported nickel phosphide catalyst according to claim 1, characterized in that, Includes the following steps: Rare earth phosphates and nickel salts are mixed and dispersed in water, and diammonium hydrogen phosphate solution is added to obtain a mixed suspension. The mixed suspension is heated and reacted, and then subjected to calcination and thermal reduction treatment to obtain the rare earth phosphate-supported nickel phosphide catalyst.

3. The method for preparing the rare earth phosphate-supported nickel phosphide catalyst according to claim 2, characterized in that, The heating reaction is carried out at a temperature of 100℃ to 120℃ for 8 to 14 hours.

4. The method for preparing the rare earth phosphate-supported nickel phosphide catalyst according to claim 2, characterized in that, The calcination process was carried out in an air atmosphere at a temperature of 600°C for 4 hours. The thermal reduction treatment was carried out in an inert gas atmosphere at a temperature of 600°C for 2 hours.

5. A method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline, characterized in that, The rare earth phosphate supported nickel phosphide catalyst according to any one of claims 1 to 4 is used as the catalyst.

6. The method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline according to claim 5, characterized in that, Includes the following steps: The 1,2-disubstituted benzimidazole was prepared by reacting an ethanol solution of furfural and o-nitroaniline with the rare earth phosphate-supported nickel phosphide catalyst in a sealed container under a hydrogen atmosphere.

7. The method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline according to claim 6, characterized in that, The pressure inside the sealed container is 0.5 MPa.

8. The method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline according to claim 6, characterized in that, In the ethanol solution of furfural and o-nitroaniline, the concentrations of furfural and o-nitroaniline are 0.1 mol / L and 0.05 mol / L, respectively.

9. The method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline according to claim 6, characterized in that, The ratio of the ethanol solution of furfural and o-nitroaniline to the rare earth phosphate-supported nickel phosphide catalyst is 1 mL: 2.5 mg.

10. The method for synthesizing 1,2-disubstituted benzimidazole by reductive amination of furfural with o-nitroaniline according to claim 6, characterized in that, The reaction was carried out at a temperature of 90°C for 8 hours.

Images