A method for preparing conjugated macromolecular triphenyls from a biomass platform compound

Abstract

The application discloses a method for preparing conjugated macromolecular triphenylene from a biomass platform compound, comprising the following steps: under the action of a photocatalyst and light, converting a stilbene substance from a trans structure to a cis structure in a solvent, and then performing a cyclization reaction and a D-A cycloaddition reaction with a diene to obtain a conjugated macromolecular triphenylene; the method is a photocatalytic synthesis method using a biomass-derived stilbene, pentadiene or substituted pentadiene, furan or substituted furan as raw materials, and compared with an original synthesis route, the method has high product selectivity, a simple separation process, and the raw materials can be derived from biomass resources, and the dependence on petroleum resources can be reduced.

Description

Technical Field

[0001] This application relates to a method for preparing the conjugated macromolecule triphenylene from biomass platform compounds, belonging to the field of organic synthesis. Background Technology

[0002] Triphenylene and its derivatives are flat polycyclic aromatic hydrocarbons (PAHs) composed of four fused benzene rings. They possess a delocalized 18π electron system based on a planar structure, corresponding to the symmetry group D. 3h Triphenylene oxide (TPO) is a key monomer for synthesizing two-dimensional large conjugated system materials. These materials have wide applications in optoelectronic materials, such as supercapacitors and fluorescent materials. Therefore, the production of TPO is crucial for the large-scale application of advanced optoelectronic materials.

[0003] Benzene, benzene, and toluene can be separated from coal tar. They can also be synthesized in several ways. One method is the trimerization of benzeneyne. Another method is synthesis using biphenyl and benzene. However, these processes are mostly derived from fossil fuels and are non-renewable. In today's era of prioritizing green and environmentally friendly practices, the development of traditional production processes is severely constrained. Therefore, there is an urgent need to develop new green energy and environmentally friendly catalytic process routes.

[0004] Stilbene, pentadiene or equivalent derivatives, furan or equivalent derivatives are important biomass platform compounds. Trans-stilbene, upon photoirradiation, can form a cis isomer and lose electrons to cyclize into an alkenophilic phenanthrene structure. Subsequently, the conjugated diene structure undergoes Diels-Alder cycloaddition and dehydration aromatization reactions to produce fully biomass-based triphenylene. However, stilbene derivatives from biomass sources are almost always trans-structured. Summary of the Invention

[0005] The purpose of this invention is to provide a technical route for preparing triphenylene and its derivative monomers from stilbene. The raw materials, stilbene, isoprene, furan, or methyl furanate, can all be derived from biomass resources.

[0006] According to one aspect of this application, a method for preparing conjugated macromolecular triphenylene from a biomass platform compound is provided, comprising the following steps:

[0007] Under the action of ultraviolet light with a wavelength of 256 nm and a photocatalyst, trans-stilbene undergoes cis-trans isomerization to form cis-stilbene, which then loses electrons and cyclizes to form a phenanthrene structure. It then undergoes a series of Diels-Alder cycloaddition and dehydration aromatization reactions with isoprene, furan, or methyl furanate in situ. After separation and purification, triphenylene products with different substitution positions are obtained.

[0008] Optionally, the following steps are included:

[0009] Under the action of photocatalyst and light, stilbene-like substances in solvent undergo a cyclization reaction, transforming from a trans structure to a cis structure, and then undergo a DA cycloaddition reaction with dienes to obtain the conjugated macromolecule triphenylene.

[0010] The stilbene-based substance has the structure shown in Formula I:

[0011]

[0012] Among them, R1, R2, R3, and R4 are each independently selected from hydrogen atoms, alkanes, hydroxyl groups, aromatic groups, and heteroaromatic groups;

[0013] The conjugated macromolecule triphenylene has the structure shown in Formula II:

[0014]

[0015] Among them, R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen atoms, alkanes, hydroxyl groups, aromatic groups, and heteroaromatic groups;

[0016] The photocatalyst is selected from at least one of anatase titanium dioxide, zinc oxide, and nitrogen carbide;

[0017] The diene is selected from at least one of isoprene, furan, and methyl furanate.

[0018] The solvent is selected from at least one of n-hexane, cyclohexane, n-heptane, n-octane, toluene, xylene, methanol, ethanol, propanol, n-butanol, isopropanol, acetonitrile, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopropyl acetate, dimethyl carbonate, or diethyl carbonate.

[0019] The molar ratio of the stilbene-based substance to the diene is 1:20 to 20:1.

[0020] Optionally, the molar ratio of the stilbene-based substance to the diene is 1:10 to 10:1;

[0021] Optionally, the molar ratio of the stilbene-based substance to the diene is 1:5 to 5:1.

[0022] The mass ratio of the stilbene-based substance to the solvent is 1:10 to 100.

[0023] The mass ratio of the photocatalyst to stilbene-based substances is 0.1 to 1:1.

[0024] The power of the illumination is 40-100W;

[0025] The wavelength of the light being illuminated is 256 nm.

[0026] The cyclization and cycloaddition reactions take 1 to 24 hours;

[0027] The cyclization and cycloaddition reactions are performed at temperatures ranging from 25 to 120°C.

[0028] The atmosphere for the cyclization and cycloaddition reactions is a nitrogen atmosphere.

[0029] The reaction process is illustrated below. The resulting conjugated macromolecule triphenylene can be used as a monomer for further polymerization.

[0030]

[0031] The beneficial effects that this application can produce include:

[0032] 1. The method for preparing the conjugated macromolecule triphenylene disclosed in this invention uses stilbene, pentadiene or substituted pentadiene, furan or substituted furan from biomass sources as raw materials for photocatalytic synthesis. Compared with the original synthesis route, the product of this invention has high selectivity, a simple separation process, and the raw materials used can be derived from biomass resources, which can reduce dependence on petroleum resources.

[0033] 2. The method of the present invention uses stilbene as raw material. The cis-trans isomerization and cyclization caused by light irradiation can quickly proceed to the next Diels-Alder reaction, avoiding multiple steps of reaction. At the same time, the series reaction will reduce the energy barrier of the overall reaction, which can achieve the rapid generation of the target product.

[0034] 3. The method of the present invention uses photocatalysis as the reaction means, which is energy-saving and environmentally friendly, highly efficient, easy to separate and purify products, and the catalyst can be recycled. The method is simple and the process is green and sustainable. Detailed Implementation

[0035] The present application is described in detail below with reference to the embodiments, but the present application is not limited to these embodiments.

[0036] Unless otherwise specified, all raw materials used in the embodiments of this application were purchased commercially. The photocatalyst was obtained commercially.

[0037] The analysis method in the embodiments of this application is as follows:

[0038] The products were qualitatively analyzed using nuclear magnetic resonance (NMR) and quantitatively analyzed using liquid chromatography with internal standard method.

[0039] In the embodiments of this application, the conversion rate and selectivity are calculated as follows:

[0040] The selectivity of each product is calculated based on the amount of stilbene fed, i.e., the formulas for calculating the reactant conversion rate and the selectivity of each product are as follows:

[0041]

[0042] The following examples will help to understand the present invention, but the scope of the present invention is not limited thereto.

[0043] Example 1: Preparation of triphenylene by reacting resveratrol with isoprene using different photocatalysts

[0044]

[0045] In a 50 mL photoreactor, 2.28 g of resveratrol (10 mmol), 6.8 g of isoprene (100 mmol), 22.8 g of methanol as reaction solvent, and 0.48 g of photocatalyst were added sequentially. After thorough mixing at room temperature, the mixture was irradiated with 365 nm ultraviolet light under a nitrogen atmosphere and reacted at 25 °C for 12 hours with magnetic stirring at 1000 rpm. Irradiation was then stopped, and a mesitylene internal standard solution was added to the reaction solution. The catalyst was removed by filtration. The products were qualitatively analyzed by NMR spectroscopy and quantitatively analyzed by liquid chromatography with internal standard method. The catalytic reaction results of different photocatalysts are shown in Table 1.

[0046] Table 1. Results of the reaction between resveratrol and isoprene catalyzed by different photocatalysts

[0047]

[0048] Example 2: Preparation of triphenylene from resveratrol and methyl furanate catalyzed by different photocatalysts

[0049]

[0050] In a 50 mL photoreactor, 2.28 g of resveratrol (10 mmol), 16.8 g of isoprene (100 mmol), 22.8 g of methanol as reaction solvent, and 0.48 g of photocatalyst were added sequentially. After thorough mixing at room temperature, the mixture was irradiated with ultraviolet light at a wavelength of 365 nm under a nitrogen atmosphere and magnetically stirred at 1000 rpm at 25 °C for 12 hours. Irradiation was then stopped, and a mesitylene internal standard solution was added to the reaction solution. The catalyst was removed by filtration. The products were qualitatively analyzed by NMR spectroscopy and quantitatively analyzed by liquid chromatography with internal standard method. The catalytic reaction results of different photocatalysts are shown in Table 1.

[0051] Table 2 Results of the reaction between resveratrol and methyl furfurylate catalyzed by different photocatalysts

[0052]

[0053]

[0054] Example 3: Titanium dioxide photocatalyst for the preparation of triphenylene from resveratrol and dimethylbutadiene

[0055] In a 50 mL photoreactor, 2.28 g of resveratrol (10 mmol), 8.2 g of isoprene (100 mmol), 22.8 g of methanol as reaction solvent, and 0.48 g of photocatalyst were added sequentially. After thorough mixing at room temperature, the mixture was irradiated with 365 nm ultraviolet light under a nitrogen atmosphere and reacted at 25 °C for 12 hours with magnetic stirring at 1000 rpm. Irradiation was then stopped, the catalyst was removed by filtration, the solvent was removed by vacuum distillation, and the final product (43% target product) was obtained by column chromatography.

[0056] Example 4: Preparation of triphenylene from resveratrol and 2,5-dimethylfuran catalyzed by carbon nitride photocatalysis

[0057] In a 50 mL photoreactor, 2.28 g of resveratrol (10 mmol), 9.6 g of 2,5-dimethylfuran (100 mmol), 22.8 g of methanol as reaction solvent, and 0.48 g of photocatalyst were added sequentially. After thorough mixing at room temperature, the mixture was irradiated with ultraviolet light at a wavelength of 365 nm under a nitrogen atmosphere and reacted at 25 °C for 12 hours with magnetic stirring at 1000 rpm. Irradiation was then stopped, the catalyst was removed by filtration, the solvent was removed by vacuum distillation, and the target product (56%) was obtained by column chromatography.

[0058] The above description is merely a few embodiments of this application and is not intended to limit this application in any way. Although this application discloses preferred embodiments as described above, it is not intended to limit this application. Any changes or modifications made by those skilled in the art without departing from the scope of the technical solution of this application using the disclosed technical content are equivalent to equivalent implementation cases and fall within the scope of the technical solution.

Claims

1. A method for preparing conjugated macromolecular triphenylene from biomass platform compounds, characterized in that, Includes the following steps: Under the action of photocatalyst and light, stilbene-like substances in solvent undergo a cyclization reaction, transforming from a trans structure to a cis structure, and then undergo a DA cycloaddition reaction with dienes to obtain the conjugated macromolecule triphenylene. The stilbene-based substance has the structure shown in Formula I: Among them, R1, R2, R3, and R4 are each independently selected from hydrogen atoms, alkanes, hydroxyl groups, aromatic groups, and heteroaromatic groups; The conjugated macromolecule triphenylene has the structure shown in Formula II: Among them, R1, R2, R3, R4, R5, and R6 are each independently selected from hydrogen atoms, alkanes, hydroxyl groups, aromatic groups, and heteroaromatic groups; The photocatalyst is selected from at least one of anatase titanium dioxide, zinc oxide, and nitrogen carbide; The diene is selected from at least one of isoprene, furan, and methyl furanate.

2. The method according to claim 1, characterized in that, The solvent is selected from at least one of n-hexane, cyclohexane, n-heptane, n-octane, toluene, xylene, methanol, ethanol, propanol, n-butanol, isopropanol, acetonitrile, methyl acetate, ethyl acetate, propyl acetate, butyl acetate, isopropyl acetate, dimethyl carbonate, or diethyl carbonate.

3. The method according to claim 1, characterized in that, The molar ratio of the stilbene-based substance to the diene is 1:20 to 20:

1. Preferably, the molar ratio of the stilbene-based substance to the diene is 1:10 to 10:1; Preferably, the molar ratio of the stilbene-based substance to the diene is 1:5 to 5:

1.

4. The method according to claim 1, characterized in that, The mass ratio of the stilbene-based substance to the solvent is 1:10 to 100.

5. The method according to claim 1, characterized in that, The mass ratio of the photocatalyst to stilbene-based substances is 0.1 to 1:

1.

6. The method according to claim 1, characterized in that, The power of the illumination is 40-100W; The wavelength of the light being illuminated is 256 nm.

7. The method according to claim 1, characterized in that, The cyclization and cycloaddition reactions take 1 to 24 hours; The cyclization and cycloaddition reactions are performed at temperatures ranging from 25 to 120°C. The atmosphere for the cyclization and cycloaddition reactions is a nitrogen atmosphere.

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