A photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and its preparation method and application

Abstract

The present invention belongs to the field of novel photocatalytic materials, and particularly relates to a photocatalyst for the efficient catalytic synthesis of halogenated aromatic hydrocarbons, as well as a preparation method and application thereof. The photocatalyst prepared by the present invention comprises titanium dioxide and a 1,4-dihydropyridine compound supported on the surface of the titanium dioxide; wherein the mass ratio of the 1,4-dihydropyridine compound to the titanium dioxide is 1:1 to 100; the present invention generates halogenated aromatic hydrocarbons by inducing a photocatalytic reaction using a visible light source. The scheme used is green, safe, and has high atomic utilization efficiency, avoids the use of toxic solvents, reduces energy consumption by reacting at room temperature, and the catalyst can be recycled and reused multiple times, reducing costs.

Description

Technical Field

[0001] The present invention belongs to the field of novel photocatalytic materials, and particularly relates to a photocatalyst for efficiently catalyzing the synthesis of halogenated aromatic hydrocarbons, and a preparation method and application thereof. Background Art

[0002] The information disclosed in this background technology section is only intended to enhance understanding of the overall background of the invention and should not necessarily be regarded as an admission or any form of suggestion that the information constitutes the prior art already known to those skilled in the art.

[0003] Halogenated aromatics have important applications in pharmaceutical research and development. They are key intermediates in the synthesis of a variety of drugs and can be functionalized through a variety of reactions to synthesize biologically active compounds. At the same time, halogenated aromatics play a very important role in organic chemistry. They not only serve as precursors for the synthesis of a variety of compounds, but also have extensive applications and research value in green synthesis, environmental governance, and materials science. Currently, the synthesis of halogenated aromatics can be achieved through a variety of methods, including electrophilic halogenation, a classic aromatic functionalization process that can produce halogenated aromatics that are of great significance in chemical synthesis and pharmaceutical research and development. In addition, halogenated aromatics can also be synthesized through electrochemical methods, using electrical energy to drive chemical reactions, realizing green synthesis technology.

[0004] Currently, halogenated aromatics are widely used in organic synthesis. They can serve as starting materials for cross-coupling reactions to form new carbon-carbon bonds (for example, the palladium-catalyzed Ullmann coupling reaction is an important method for constructing carbon-carbon bonds using halogenated aromatics). They can also be converted into corresponding hydrides through hydrogenolysis dehalogenation reactions, which is not only an important synthetic strategy but also has the potential to become an important method for the detoxification of toxic halides.

[0005] In the field of environmental remediation, the microbial degradation of halogenated aromatic hydrocarbons has garnered widespread attention. Microorganisms can transform halogenated aromatic hydrocarbons into harmless or less toxic substances through their metabolic pathways, which is of great significance to environmental protection. Furthermore, the reuse of halogenated organic pollutants as halogen sources not only helps reduce environmental pollution but also allows for the synthesis of high-value-added products, which has become a research hotspot.

[0006] The traditional Wohl-Ziegler bromination reaction usually uses carbon tetrachloride (CCl4) as a solvent (Ziegler, K.; Spath, A.; Schaaf, E.; Schumann, W.; Winkelmann, E. Justus Liebigs Ann. Chem. 1942, 551, 80-119). However, CCl4 is a Class 2B carcinogen and has a destructive effect on the ozone layer, and its use has been restricted by international conventions. The classic global Ziegler bromination uses bromosuccinimide (NBS) with carbon tetrachloride as a reflux solvent and a high-energy initiator such as benzoyl peroxide (Veisi, H.; Ghorbani-Vaghei, R.; Zolfigol, MA Org. Prep. Proced. Int. 2011, 43, 489-540.), and this type of alternative method is still often chosen. (Haberhauer, G.; Tepper, C.; Wolper, C.; Blaser, D. Eur. J. Org. Chem. 2013, 2325-2333.).

[0007] Although NBS is a relatively safe and user-friendly brominating agent compared to liquid bromine (Br), the Wohl-Ziegler bromination protocol also uses the toxic and ozone-depleting solvent carbon tetrachloride. Over the past few years, researchers have been working hard to develop green bromination procedures, mainly focusing on replacing hazardous carbon tetrachloride with more benign solvents. Currently, there are several bromination protocols using non-chlorinated solvents such as methyl acetate, ethyl acetate and valerate, trifluoromethylbenzene, and acetonitrile. Alternative brominating agents have also been studied, as well as different activation methods, especially ultraviolet or visible light-induced bromination reactions to avoid the use of dangerous and potentially explosive free radical initiators such as benzoyl peroxide. Therefore, designing a catalyst with green, safe, and high atom utilization characteristics is an urgent problem to be solved by those skilled in the art. Summary of the Invention

[0008] To address the above-mentioned technical problems, the present invention aims to provide a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons, as well as a preparation method and application thereof. The photocatalyst prepared by the present invention generates halogenated aromatic hydrocarbons by inducing a photocatalytic reaction using visible light. This method is both environmentally friendly and safe. It also avoids the use of toxic solvents and operates at room temperature, significantly reducing energy consumption. Furthermore, the catalyst can be recycled and reused multiple times, significantly reducing costs.

[0009] In order to achieve the above object, the present invention is implemented through the following technical solutions:

[0010] In a first aspect, the present invention provides a photocatalyst comprising titanium dioxide and a 1,4-dihydropyridine compound supported on the surface of the titanium dioxide; the mass ratio of the 1,4-dihydropyridine compound to the titanium dioxide is 1:1 to 100;

[0011] Wherein, the 1,4-dihydropyridine compound is selected from one of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine (DPAD), 1,4-dihydro-4-(4-hydroxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester, 1,4-dihydro-2,6-dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid diethyl ester, 1,4-dihydro-4-(4-methoxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester, 3,5-diethyl 4-(4-fluorophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate, and 3,5-diethyl 4-(4-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate.

[0012] In a second aspect, the present invention provides a method for preparing the above-mentioned photocatalyst, comprising: mixing a 1,4-dihydropyridine compound and titanium dioxide, dissolving the mixture in an organic solvent, and subjecting the mixture to a hydrothermal reaction to generate the photocatalyst.

[0013] Preferably, the organic solvent is selected from one or more of N,N-dimethylformamide (DMF), dimethylacetamide (DMA), dimethyl sulfoxide (DMSO), acetonitrile, methanol, anhydrous ethanol, isopropanol, n-butanol, isobutanol, water, and tetrahydrofuran.

[0014] Preferably, the crystal form of the titanium dioxide is anatase type, including nanometer and micrometer sizes.

[0015] Preferably, the temperature of the hydrothermal reaction is 100-380° C., and the time is 5-15 hours.

[0016] Preferably, the product after the hydrothermal reaction is filtered and dried in sequence; further preferably, the filtering method is vacuum filtration.

[0017] In a third aspect, the present invention provides a method for catalytically synthesizing halogenated aromatic products, comprising: catalyzing a reaction between an aromatic substrate and a halogenating agent using the photocatalyst described in the first aspect under irradiation with a visible light source to generate a halogenated aromatic product.

[0018] Preferably, the amount of the photocatalyst added is 1% to 20% of the total mass of the aromatic hydrocarbon substrate and the halogenation reagent.

[0019] Preferably, the molar ratio of the aromatic hydrocarbon substrate to the halogenating agent is 1:1-3.

[0020] Preferably, the aromatic hydrocarbon substrate has a structure shown in Formula I:

[0021]

[0022] Among them, R 1 is a substituent on the parent benzene ring selected from hydrogen, alkyl, substituted alkyl, and halogen;

[0023] R 2 Selected from hydrogen, alkyl, substituted alkyl, amino, carboxyl, ester, acyl, halogen, aryl, and substituted aryl.

[0024] Preferably, R 1 The substitution position is selected from the 4-position or 6-position on the benzene ring;

[0025] Preferably, R 1 Selected from hydrogen, trifluoromethyl, fluorine, chlorine, bromine, iodine;

[0026] Preferably, R 2 is selected from hydrogen, amino, carboxyl, C1-C6 alkyl, C1-C6 ester, C1-C6 acyl, fluorine, chlorine, bromine, iodine, phenyl, and substituted phenyl; wherein the substituted phenyl is selected from C1-C6 alkyl, C1-C6 ester, C1-C6 acyl, and halogen;

[0027] Preferably, R 2 Selected from hydrogen, C1-C3 alkyl, methyl group, carboxyl group.

[0028] Preferably, the halogenating agent is selected from one or more of concentrated hydrochloric acid, hydrobromic acid, hydrofluoric acid, iodic acid, elemental fluorine, chlorine, bromine, iodine, N-bromosuccinimide (NBS), N-chlorosuccinimide (NCS) and N-iodosuccinimide (NIS).

[0029] Preferably, the aromatic hydrocarbon substrate is first dissolved in an organic solvent, and then a halogenating agent is added to carry out the reaction; further preferably, the organic solvent is selected from one or more of toluene, DMF, DMA, acetonitrile, tetrahydrofuran, pyridine, methanol, anhydrous ethanol, dichloromethane, dichloroethane, ethyl acetate, and ethyl formate.

[0030] Preferably, the visible light source is selected from one or more of a xenon lamp light source with a power of 50 to 500W and an LED lamp light source with a power of 50 to 500W.

[0031] Preferably, after the reaction, the product is concentrated, extracted, dried, and subjected to column chromatography.

[0032] Preferably, the extraction agent used in the extraction is selected from one or more of DMF, DMA, acetonitrile, tetrahydrofuran, pyridine, methanol, anhydrous ethanol, dichloromethane, dichloroethane, ethyl acetate, and ethyl formate; the drying agent used is anhydrous sodium sulfate; and the eluent for the column chromatography is a petroleum ether / ethyl acetate elution system with a volume ratio of 9:1 to 5:1.

[0033] Preferably, the solid obtained after filtration is dried, soaked in a solvent and then dried to obtain a reusable photocatalyst; preferably, the solvent is selected from methanol 、 One or more of water, DMF.

[0034] In a fourth aspect, the present invention provides a use of the photocatalyst described in the first aspect in the catalytic synthesis of halogenated aromatic hydrocarbon products.

[0035] The beneficial effects achieved by one or more technical solutions of the present invention are as follows:

[0036] (1) The photocatalyst prepared by the present invention generates halogenated aromatic hydrocarbons by inducing a photocatalytic reaction using a visible light source, and the scheme used is green and safe.

[0037] (2) The photocatalyst prepared by the present invention avoids the use of toxic solvents and reacts at room temperature, which greatly reduces energy consumption. In addition, the catalyst can be recycled and reused multiple times, which greatly reduces costs and has practical application value.

[0038] (3) The present invention loads 1,4-dihydropyridine compounds with titanium dioxide and combines them through organic bonds, so that the catalyst has good reusability. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] Figure 1 X-ray photoelectron spectrum of the photocatalyst prepared in Example 1 of the present invention, wherein (a) is the full spectrum of 0.1DPAD-TiO2-380, (b) is the full spectrum of 0.1DPAD-TiO2-180, (c) is the C1s spectrum of 0.1DPAD-TiO2-380, (d) is the O1s spectrum of 0.1DPAD-TiO2-380, (e) is the Ti2p spectrum of 0.1DPAD-TiO2-380, (f) is the C1s spectrum of 0.1DPAD-TiO2-180, (g) is the O1s spectrum of 0.1DPAD-TiO2-180, and (h) is the Ti2p spectrum of 0.1DPAD-TiO2-180;

[0040] Figure 2 The UV-visible diffuse reflectance spectrum of the photocatalyst prepared in Example 1 of the present invention;

[0041] Figure 3The Fourier transform infrared spectrum of the photocatalyst prepared in Example 1 of the present invention;

[0042] Figure 4 This is the hydrogen nuclear magnetic resonance spectrum of 1-bromoethylbenzene catalytically synthesized in Application Example 1 of the present invention;

[0043] Figure 5 This is the H NMR spectrum of methyl bromophenylacetate catalytically synthesized in Application Example 2 of the present invention;

[0044] Figure 6 This is the H NMR spectrum of 4-fluorophenethyl bromide catalytically synthesized in Application Example 3 of the present invention;

[0045] Figure 7 This is the H NMR spectrum of the catalytic synthesis of 1-(1-bromoethyl)-4-(trifluoromethyl)benzene obtained in Application Example 4 of the present invention;

[0046] Figure 8 This is the H NMR spectrum of α-bromophenylacetic acid catalytically synthesized in Application Example 5 of the present invention;

[0047] Figure 9 This is the H NMR spectrum of α-bromo-2-chlorophenylacetic acid catalytically synthesized in Application Example 7 of the present invention;

[0048] Figure 10 This is a TLC thin layer chromatography spot plate monitoring chart of the catalytic synthesis of 1-bromoethylbenzene in Comparative Example 1 of the present invention;

[0049] Figure 11 This is a cycle performance test of the photocatalyst prepared in Example 1 of the present invention. DETAILED DESCRIPTION

[0050] It should be noted that the following detailed descriptions are exemplary and intended to provide further explanation of the present invention. Unless otherwise specified, all technical and scientific terms used in the present invention have the same meanings as those commonly understood by those skilled in the art to which the present invention belongs.

[0051] The raw materials and reagents used in the present invention are as follows:

[0052] Table 1 Main raw materials and reagents

[0053]

[0054]

[0055] The present invention will be further described in detail below with reference to specific embodiments. It should be noted that the specific embodiments are intended to explain the present invention rather than to limit it.

[0056] Example 1This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0057] (1) Preparation of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine:

[0058] 100 mL of ethylene tar was reacted at 400°C and 4 MPa for 6 hours, then cooled to yield 20 g of petroleum coke product. The petroleum coke product was soaked in 40 mL of 36% concentrated hydrochloric acid in a 250 mL beaker. After stirring at room temperature for 24 hours, 100 mL of water was added and the mixture was filtered under reduced pressure. The resulting 20 g of solid was dried and used as the petroleum coke catalyst. To a 500 mL three-necked flask, 262 mL of ethyl acetoacetate, 137 g of p-dimethylaminobenzaldehyde, and 81 g of ammonium acetate were added, along with 20 g of the petroleum coke catalyst. The mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, a large amount of solid was obtained. The solid was filtered and redissolved in 50 mL of anhydrous ethanol. The black petroleum coke catalyst was separated by filtration. The remaining filtrate was allowed to crystallize, yielding 301 g of a yellow solid compound, namely, 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine (DPAD).

[0059] (2) 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine were stirred in 20 g of DMA solvent at room temperature for 12 h. The mixed solution was hydrothermally reacted at 180 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure and the filter cake was washed with methanol. The obtained solid was dried to obtain the photocatalyst (0.1DPAD-TiO2-180).

[0060] Example 2 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0061] (1) Preparation of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine:

[0062] 100 mL of ethylene tar was reacted at 400°C and 4 MPa for 6 hours, then cooled to yield 20 g of petroleum coke product. The petroleum coke product was soaked in 40 mL of 36% concentrated hydrochloric acid in a 250 mL beaker. After stirring at room temperature for 24 hours, 100 mL of water was added and the mixture was filtered under reduced pressure. The resulting 20 g of solid was dried and used as the petroleum coke catalyst. To a 500 mL three-necked flask, 262 mL of ethyl acetoacetate, 137 g of p-dimethylaminobenzaldehyde, and 81 g of ammonium acetate were added, along with 20 g of the petroleum coke catalyst. The mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, a large amount of solid was obtained. The solid was filtered and redissolved in 50 mL of anhydrous ethanol. The black petroleum coke catalyst was separated by filtration. The remaining filtrate was allowed to crystallize, yielding 301 g of a yellow solid compound, namely, 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine (DPAD).

[0063] (2) 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine were stirred in 20 g of DMA solvent at room temperature for 12 h. The mixed solution was hydrothermally reacted at 380 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure and the filter cake was washed with methanol. The obtained solid was dried to obtain the photocatalyst (0.1DPAD-TiO2-380).

[0064] Example 3 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0065] (1) Preparation of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine:

[0066] 100 mL of ethylene tar was reacted at 400°C and 4 MPa for 6 hours, then cooled to yield 20 g of petroleum coke product. The petroleum coke product was soaked in 40 mL of 36% concentrated hydrochloric acid in a 250 mL beaker. After stirring at room temperature for 24 hours, 100 mL of water was added and the mixture was filtered under reduced pressure. The resulting 20 g of solid was dried and used as the petroleum coke catalyst. To a 500 mL three-necked flask, 262 mL of ethyl acetoacetate, 137 g of p-dimethylaminobenzaldehyde, and 81 g of ammonium acetate were added, along with 20 g of the petroleum coke catalyst. The mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, a large amount of solid was obtained. The solid was filtered and redissolved in 50 mL of anhydrous ethanol. The black petroleum coke catalyst was separated by filtration. The remaining filtrate was allowed to crystallize, yielding 301 g of a yellow solid compound, namely, 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine (DPAD).

[0067] (2) 0.2 g of 30 nm anatase titanium dioxide and 0.01 g of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine were stirred in 20 g of DMA solvent at room temperature for 12 h. The mixed solution was hydrothermally reacted at 180 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure and the filter cake was washed with methanol. The obtained solid was dried to obtain the photocatalyst (0.05DPAD-TiO2).

[0068] Example 4 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0069] (1) Preparation of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine:

[0070] 100 mL of ethylene tar was reacted at 400°C and 4 MPa for 6 hours, then cooled to yield 20 g of petroleum coke product. The petroleum coke product was soaked in 40 mL of 36% concentrated hydrochloric acid in a 250 mL beaker. After stirring at room temperature for 24 hours, 100 mL of water was added and the mixture was filtered under reduced pressure. The resulting 20 g of solid was dried and used as the petroleum coke catalyst. To a 500 mL three-necked flask, 262 mL of ethyl acetoacetate, 137 g of p-dimethylaminobenzaldehyde, and 81 g of ammonium acetate were added, along with 20 g of the petroleum coke catalyst. The mixture was stirred at room temperature for 24 hours. Upon completion of the reaction, a large amount of solid was obtained. The solid was filtered and redissolved in 50 mL of anhydrous ethanol. The black petroleum coke catalyst was separated by filtration. The remaining filtrate was allowed to crystallize, yielding 301 g of a yellow solid compound, namely, 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine (DPAD).

[0071] (2) 0.2 g of 30 nm anatase titanium dioxide and 0.04 g of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine were stirred in 20 g of DMA solvent at room temperature for 12 h. The mixed solution was hydrothermally reacted at 180 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure and the filter cake was washed with methanol. The obtained solid was dried to obtain the photocatalyst (0.2DPAD-TiO2).

[0072] Example 5 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0073] 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 1,4-dihydro-4-(4-hydroxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester were stirred in 20 g of DMF solvent at room temperature for 6 h, and the mixed solution was hydrothermally reacted at 220 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure, the filter cake was washed with methanol, and the obtained solid was dried to obtain a photocatalyst.

[0074] Example 6 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0075] 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 1,4-dihydro-2,6-dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid diethyl ester were stirred in 20 g of methanol solvent at room temperature for 12 hours, and the mixed solution was hydrothermally reacted at 150 ° C for 12 hours. After the reaction was completed, it was filtered under reduced pressure, the filter cake was washed with methanol, and the obtained solid was dried to obtain a photocatalyst.

[0076] Example 7 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0077] 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 1,4-dihydro-4-(4-methoxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester were stirred in 30 g of DMSO solvent at room temperature for 12 hours, and the mixed solution was hydrothermally reacted at 250 ° C for 8 hours. After the reaction was completed, it was filtered under reduced pressure, the filter cake was washed with methanol, and the obtained solid was dried to obtain a photocatalyst.

[0078] Example 8 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0079] 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 3,5-diethyl 4-(4-fluorophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate were stirred in 40 g of anhydrous ethanol solvent at room temperature for 12 hours, and the mixed solution was hydrothermally reacted at 200 ° C for 12 hours. After the reaction was completed, it was filtered under reduced pressure, the filter cake was washed with methanol, and the obtained solid was dried to obtain a photocatalyst.

[0080] Example 9 This embodiment provides a photocatalyst for the efficient synthesis of halogenated aromatic hydrocarbons and a method for preparing the same

[0081] 0.2 g of 30 nm anatase titanium dioxide and 0.02 g of 3,5-diethyl 4-(4-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate were stirred in 20 g of methanol solvent at room temperature for 12 h, and the mixed solution was hydrothermally reacted at 160 ° C for 12 h. After the reaction was completed, it was filtered under reduced pressure, the filter cake was washed with methanol, and the obtained solid was dried to obtain a photocatalyst.

[0082] Example 10 The photocatalysts prepared in Examples 1 and 2 were analyzed by X-ray photoelectron spectroscopy (XPS) and UV-visible diffuse reflectance spectroscopy.

[0083] like Figure 1As shown, the photocatalysts prepared in Example 1 and Example 2 were subjected to XPS qualitative analysis. It can be seen from the figure that the peaks of C, N, O, and Ti can be clearly displayed in the full spectra of (a) and (b), proving that DPAD and TiO2 are combined with each other after the thermal reaction process; (c), (d), and (e) are the C1s, O1s, and Ti2p spectra of 0.1DPAD-TiO2-380, respectively; it can be clearly seen that C1s is fitted into four peaks, and it can be seen that CC, C=C, COC, and -CC=O exist, which are located at 284.81, 283.94, 285.71, and 288.51 eV, respectively. From O1s, it can be seen that three peaks are fitted, and it can be seen that Ti-O, C=O, and CO exist, which are located at 529.91, 531.65, and 533 eV, respectively. From the Ti2p spectrum, there are obvious Ti2p orbital characteristic peaks at 458.78 and 464.35 eV, indicating that Ti 4+ (f), (g), and (h) are the C1s, O1s, and Ti2p spectra of 0.1DPAD-TiO2-180, respectively. It can be clearly seen that C1s is fitted into three peaks, indicating the presence of CC, COC, and -CC=O, located at 284.81, 285.2, and 288.8 eV, respectively. O1s is fitted into three peaks, indicating the presence of Ti-O, C=O, and CO, located at 529.85, 531.7, and 533.5 eV, respectively. From the Ti2p spectrum, obvious Ti2p orbital characteristic peaks appear at 458.65 and 464.38 eV, indicating that Ti 4+ exists; in summary, it can be fully explained that the organic matter is loaded on titanium dioxide through chemical bonds.

[0084] like Figure 2 As shown in the UV diffuse reflectance spectra of TiO2, 0.1DPAD-TiO2-380, and 0.1DPAD-TiO2-180, it can be seen that TiO2 alone has almost no absorption in the visible light region, but has strong absorption in the UV absorption region after combining with DPAD. Therefore, it can be seen from the figure that DPAD modification of TiO2 effectively increases the catalyst's absorption at 400-600nm, indicating that DPAD modification effectively improves the catalyst's utilization of visible light.

[0085] Example 11 : This example is to carry out Fourier transform infrared spectroscopy analysis on the photocatalyst prepared in Example 1 and Example 3-4

[0086] like Figure 3 As shown in the figure, the Fourier transform infrared spectroscopy results show that the organic DPAD has a peak at 3352 cm -1 There is a strong NH absorption peak at 1615 cm -1There is the bending vibration of the NH of the primary amine at 1510~1480cm -1 The skeletal vibration of the benzene ring is 1697 cm -1 The peak is C=O, which is due to the C=C-CO-OR environment causing the absorption to shift to a lower wave number; 1646 cm -1 The stretching vibration of C=C is 1206cm -1 is the stretching vibration of the CO bond, 1370cm -1 It is the deformation vibration of -CH3 bond. After doping with TiO2, 3400~3200cm -1 The peak of NH is covered by the -OH peak of TiO2, so the peak of NH is not visible. At the same time, the intensity of the characteristic peak of DPAD increases with the increase of DPAD concentration compared with TiO2.

[0087] As described above, through X-ray photoelectron spectroscopy (XPS), UV-visible diffuse reflectance spectroscopy and Fourier transform infrared spectroscopy analysis of the raw materials DPAD, TiO2 and the generated catalyst (DPAD-TiO2), it can be clearly seen that the organic substance DPAD is successfully bonded to titanium dioxide in the form of a chemical bond.

[0088] Application Example 1 This application example uses the photocatalyst prepared in Example 1 to catalyze the synthesis of 1-bromoethylbenzene, comprising the following steps:

[0089] S1. Add 10 mL of benzyl alcohol to a 100 mL beaker with a jacket, add 30 mL of dichloromethane, add 0.3 g of the prepared photocatalyst, add 16.41 g of N-bromosuccinimide (NBS), and react under 200 W xenon lamp light source for 15 min.

[0090] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0091] S3. The reaction solution after filtration was concentrated, 15 mL of water was added, and the product was extracted with 20 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 85%.

[0092] like Figure 4 As shown, the data characterization: 1H NMR (400MHz, CDCl3) δ7.43(d,J=7.6Hz,2H),7.33(t,J=7.7Hz,2H),7.28(d,J=7.2Hz,1H),5.21(q,J=7.2Hz,1H),2.04(d,J=7.0Hz,3H).

[0093] Application Example 2 This application example catalyzes the synthesis of methyl bromophenylacetate using the photocatalyst prepared in Example 2, comprising the following steps:

[0094] S1. Add 10 mL of DL-methyl mandelate to a 100 mL jacketed beaker, add 30 mL of dichloromethane, add 10.71 g of NBS, and add 0.5 g of the prepared photocatalyst. The mixture was irradiated with a 100 W xenon lamp and reacted for 25 min.

[0095] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0096] S3. The reaction solution after filtration was concentrated, 25 mL of water was added, and the product was extracted with 40 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 90%.

[0097] like Figure 5 As shown, the data characterization: 1 H NMR (400MHz, CDCl3) δ7.61-7.42(m,2H),7.41-7.32(m,3H),5.36(d,J=2.7Hz,1H),3.78(d,J=2.8Hz,3H).

[0098] Application Example 3 This application example catalyzes the synthesis of 4-fluorophenethyl bromide using the photocatalyst prepared in Example 3, comprising the following steps:

[0099] S1. Add 20 mL of 1-(4-fluorophenyl)-1-anhydrous ethanol to a 100 mL beaker with a jacket, add 40 mL of dichloromethane, add 25.39 g of NBS, and add 1.5 g of the prepared photocatalyst. The reaction was carried out under irradiation with a 200 W xenon lamp light source for 30 min.

[0100] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0101] S3. The reaction solution after filtration was concentrated, 40 mL of water was added, and the product was extracted with 40 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 75%.

[0102] like Figure 6 As shown, the data characterization: 1 H NMR (400MHz, CDCl3) δ7.40 (dd, J = 8.5, 5.1Hz, 2H), 7.01 (t, J = 8.7Hz, 2H), 5.19 (q, J = 7.2Hz, 1H), 2.02 (d, J = 6.9Hz, 3H).

[0103] Application Example 4 This application example catalyzes the synthesis of 1-(1-bromoethyl)-4-(trifluoromethyl)benzene using the photocatalyst prepared in Example 4, comprising the following steps:

[0104] S1. Add 20 mL of α-methyl-4-(trifluoromethyl)benzyl alcohol to a 100 mL beaker with a jacket, add 50 mL of dichloromethane, add 2 g of the prepared photocatalyst, add 26.41 g of N-bromosuccinimide (NBS), and react under 200 W xenon lamp light source for 15 min.

[0105] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0106] S3. The reaction solution after filtration was concentrated, 15 mL of water was added, and the product was extracted with 20 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 85%.

[0107] like Figure 7 As shown, the data characterization: 1 H NMR (400MHz, CDCl3) δ7.68 (s, 1H), 7.63 (d, J = 7.9Hz, 1H), 7.55 (d, J = 8Hz, 1H), 7.46 (t, J = 8.1Hz, 1H), 5.26-5.15 (m, 1H), 2.05 (dd, J = 6.9, 2.7Hz, 3H).

[0108] Application Example 5This application example uses the photocatalyst prepared in Example 5 to catalyze the synthesis of α-bromophenylacetic acid, comprising the following steps:

[0109] S1. Add 10 mL of DL-mandelic acid to a 100 mL jacketed beaker, add 30 mL of dichloromethane, add 0.8 g of the prepared photocatalyst, and add 14.1 g of N-bromosuccinimide (NBS). The mixture is irradiated with a 200 W xenon lamp and the reaction is stopped after 15 min.

[0110] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0111] S3. The reaction solution after filtration was concentrated, 15 mL of water was added, and the product was extracted with 20 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 85%.

[0112] like Figure 8 As shown, the data characterization: 1 H NMR (400MHz, CDCl3) δ10.72(s,1H),10.39(s,1H),7.58-7.52(m,4H),7.40-7.34(m,6H),5.35(s,2H).

[0113] Application Example 6 This application example uses the photocatalyst prepared in Example 6 to catalyze the synthesis of α-bromo-2-chlorophenylacetic acid, comprising the following steps:

[0114] S1. Add 10 mL of 2-chloromandelic acid to a 100 mL beaker with a jacket, add 30 mL of dichloromethane, add 1.1 g of the prepared photocatalyst, and add 15.2 g of N-bromosuccinimide (NBS). The mixture is irradiated with a 200 W xenon lamp and the reaction is stopped after 15 min.

[0115] S2, filtering the reaction solution, drying the obtained solid, soaking it in 30 mL of methanol, evaporating the solvent to obtain a dried solid, which is a reusable photocatalyst;

[0116] S3. The reaction solution after filtration was concentrated, 15 mL of water was added, and the product was extracted with 20 mL of ethyl acetate. The extraction was repeated three times to collect the ethyl acetate layer, which was dried over anhydrous sodium sulfate. The organic layer was concentrated and separated by column chromatography using petroleum ether: ethyl acetate = 9:1 to 5:1 to obtain an oily liquid product with a yield of 85%.

[0117] like Figure 9 As shown, the data characterization: 1 H NMR (400MHz, CDCl3) δ9.47 (s, 2H), 7.81-7.74 (m, 1H), 7.39 (d, J = 7.0Hz, 1H), 7.32 (d, J = 8.2Hz, 2H), 5.95 (d, J = 3.2Hz, 1H).

[0118] Comparative Example 1 : This comparative example catalyzes the synthesis of 1-bromoethylbenzene using a single DPAD compound, comprising the following steps:

[0119] S1. Add 10 mL of benzyl alcohol to a 100 mL jacketed beaker, add 30 mL of dichloromethane, add 0.3 g of DPAD, and add 16.41 g of N-bromosuccinimide (NBS), and react under 200 W xenon lamp light source for 15 min.

[0120] S2. Filter the reaction solution, rinse the filter cake with 30 mL of methanol, and dry and weigh the filter cake to obtain 0.3 g of a yellow solid;

[0121] S3. The filtered reaction solution is monitored using a TLC thin layer chromatography plate.

[0122] The results are as follows Figure 10 As shown: Through thin layer chromatography analysis, the main reaction raw materials, benzyl alcohol, NBS bromination reagent and target product were spotted. As shown in the figure, the reaction liquid after filtration was spotted on the far right, and it was found that no target product spots appeared in the reaction liquid. This shows that the single DPAD organic compound has no ability to catalyze the reaction.

[0123] Test Example 1 :This test example tests the cycling performance of the photocatalyst prepared in Example 1

[0124] Experimental process: Benzyl alcohol was used as the reactant, and the yield of the generated brominated product was used as the performance evaluation index of the catalyst's reusability (catalytic synthesis process of Application Example 1). Figure 11 It can be seen that after five repeated experiments, the yield of the product did not show a significant decrease (difference: 1.2~2), indicating that the catalyst has good reusability.

[0125] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations of the present invention are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. An application of a photocatalyst in the photocatalytic reaction of an aromatic hydrocarbon substrate with a halogenating agent to synthesize a halogenated aromatic hydrocarbon product, characterized in that: The photocatalyst includes titanium dioxide and a 1,4-dihydropyridine compound supported on the surface of the titanium dioxide; the mass ratio of the 1,4-dihydropyridine compound to the titanium dioxide is 1:1 to 100; the 1,4-dihydropyridine compound is supported on the titanium dioxide and is bonded via an organic bond; Wherein, the 1,4-dihydropyridine compound is selected from one of 4-(4-(dimethylamino)phenyl)-2,6-dimethyl-3,5-dicarboxylic acid diethyl ester-1,4-dihydropyridine, 1,4-dihydro-4-(4-hydroxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester, 1,4-dihydro-2,6-dimethyl-4-phenyl-3,5-pyridinedicarboxylic acid diethyl ester, 1,4-dihydro-4-(4-methoxyphenyl)-2,6-dimethyl-3,5-pyridinedicarboxylic acid diethyl ester, 3,5-diethyl-4-(4-fluorophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate, and 3,5-diethyl-4-(4-nitrophenyl)-1,4-dihydro-2,6-dimethyl-3,5-pyridinedicarboxylate; The crystal form of the titanium dioxide is anatase, including nanometer and micrometer sizes; The preparation method of the photocatalyst comprises: mixing 1,4-dihydropyridine compounds and titanium dioxide, dissolving the mixture in an organic solvent, and performing a hydrothermal reaction to generate the photocatalyst.

2. The use according to claim 1, characterized in that The organic solvent is selected from one or more of N,N-dimethylformamide, dimethylacetamide, dimethyl sulfoxide, acetonitrile, methanol, anhydrous ethanol, isopropanol, n-butanol, isobutanol, and tetrahydrofuran.

3. The use according to claim 1, characterized in that The temperature of the hydrothermal reaction is 100-380° C., and the time is 5-15 h.

4. The use according to claim 1, wherein The product after the hydrothermal reaction is filtered and dried in sequence.

5. The use according to claim 4, characterized in that The filtering method is vacuum filtration.

6. The use according to claim 1, wherein Applications include: under the irradiation of visible light, the photocatalyst catalyzes the reaction of aromatic hydrocarbon substrates with halogenation reagents to generate halogenated aromatic hydrocarbon products.

7. The use according to claim 6, characterized in that The amount of the photocatalyst added is 1%-20% of the total mass of the aromatic hydrocarbon substrate and the halogenation reagent, and the molar ratio of the aromatic hydrocarbon substrate to the halogenation reagent is 1:1-3.

8. The use according to claim 6, characterized in that The aromatic hydrocarbon substrate has a structure shown in Formula I: Formula I; Among them, R 1 is a substituent on the parent benzene ring selected from hydrogen, alkyl or halogen; R 2 is selected from hydrogen, alkyl, amino, carboxyl, ester, acyl, halogen or aryl.

9. The use according to claim 8, characterized in that The R 1 The substitution position is selected from the 4-position or 6-position on the benzene ring.

10. The use according to claim 8, characterized in that The R 1 is selected from hydrogen, fluorine, chlorine, bromine or iodine.

11. The use according to claim 8, wherein The R 2 is selected from hydrogen, amino, carboxyl, C1~C6 alkyl, C1~C6 ester, C1~C6 acyl, fluorine, chlorine, bromine, iodine, phenyl, and substituted phenyl; wherein the substituent of the substituted phenyl is selected from C1~C6 alkyl, C1~C6 ester, C1~C6 acyl or halogen.

12. The use according to claim 11, characterized in that The R 2 Selected from hydrogen, C1~C3 alkyl, methyl group or carboxyl group.

13. The use according to claim 6, characterized in that The halogenating agent is selected from one or more of concentrated hydrochloric acid, hydrobromic acid, hydrofluoric acid, iodic acid, elemental fluorine, elemental chlorine, elemental bromine, elemental iodine, N-bromosuccinimide, N-chlorosuccinimide and N-iodosuccinimide.

14. The use according to claim 6, characterized in that The aromatic hydrocarbon substrate is first dissolved in an organic solvent, and then a halogenating reagent is added to carry out the reaction.

15. The use according to claim 14, characterized in that The aromatic hydrocarbon substrate is first dissolved in an organic solvent, wherein the organic solvent is selected from one or more of toluene, DMF, DMA, acetonitrile, tetrahydrofuran, pyridine, methanol, anhydrous ethanol, dichloromethane, dichloroethane, ethyl acetate, and ethyl formate.

16. The use according to claim 6, wherein: The visible light source is selected from one or more of a xenon lamp light source with a power of 50-500 W and a LED light source with a power of 50-500 W.

17. The use according to claim 6, characterized in that After the reaction, the product is filtered, concentrated, extracted, dried, and subjected to column chromatography.

18. The use according to claim 17, characterized in that The extraction agent used in the extraction is selected from one or more of DMF, DMA, acetonitrile, tetrahydrofuran, pyridine, methanol, anhydrous ethanol, dichloromethane, dichloroethane, ethyl acetate, and ethyl formate; the drying agent used is anhydrous sodium sulfate; and the eluent for the column chromatography is a petroleum ether / ethyl acetate elution system with a volume ratio of 9:1 to 5:

1.

19. The use according to claim 17, wherein: The solid obtained after filtering is dried, soaked in a solvent and then dried to obtain a reusable photocatalyst.

20. The use according to claim 19, characterized in that The solid obtained after filtration is dried, soaked in a solvent and then dried, wherein the solvent is selected from one or more of methanol, water and DMF.

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