Photochromic catalyst for synthesizing monobenzone and cell blocker through photocatalysis C-Cl bond activation and preparation method of photochromic catalyst

Abstract

According to the research, a novel photooxidation reduction system based on the photochromic Cu-TiO2 nano-catalyst is developed, and efficient activation and selective coupling of C-Cl bonds under visible light driving are successfully achieved. Through a dual reaction path of concerted catalysis of benzyl chloride reduction and phenol oxidation, the system can directionally synthesize C-C / C-O bond drug molecules such as 4-benzyloxyphenol (monobenzone) and benzylated 1, 4-benzoquinone. Mechanism research shows that Cu doping enhances the coordination capacity of a substrate, Cu / Cu active sites generated by excitation of Cu doping have a synergistic effect with oxygen vacancies, the C-Cl bond activation efficiency is remarkably improved, and efficient synthesis of bibenzyl (the yield is gt, 96%, and the selectivity is gt, 99%) is achieved. The photooxidation path can be selectively controlled by regulating and controlling the solvent environment, so that accurate synthesis of high-added-value drugs of different bond type products is realized. The work provides a new thought for developing a high-efficiency photocatalytic drug synthesis system, and has important guiding significance for functional research of C-Cl bonds.

Description

Technical Field

[0001] This invention relates to a method for preparing and applying an inorganic photochromic catalyst for C-Cl bond activation and functionalization coupling reactions, belonging to the field of fine chemical technology. Background Technology

[0002] Alkyl halides are crucial substrates in organic synthesis, with wide-ranging applications in fields such as pharmaceuticals, chemical engineering, and materials science. They are readily available, inexpensive, and exhibit good stability. For these reasons, organohalides are widely used as alkylating agents in nucleophilic and aryl substitution reactions, as well as substrates in transition metal-catalyzed reactions.

[0003] Currently, many related studies focus on alkyl bromides because the energy of the C-Br bond (285 kJ / mol) is relatively low. -1 The energy of the C-Cl bond (327 kJ mol) -1 The concentration of alkyl chlorides is much lower than that of organic bromides, making them easier to activate and allowing for better control of product selectivity. However, compared to organic bromides, organic chlorides offer superior performance due to their lower cost, greater abundance, better stability, ease of storage, and lower toxicity. However, due to their inert nature, alkyl chlorides are often considered inert substrates in organic reactions, making it challenging to achieve high yields and selectivity in the activation and functionalization of high-value-added drug molecules using alkyl chlorides as reaction substrates. While homogeneous photocatalysis systems can effectively activate C-Cl bonds, catalyst recovery is often problematic. In contrast, heterogeneous photocatalysis offers a more attractive alternative due to its cost-effectiveness, environmental friendliness, and sustainability. In recent years, significant progress has been made in the research and application of inorganic semiconductor photocatalysts, attracting widespread attention. However, the low charge separation efficiency and slow carrier migration rate commonly found in these materials severely limit their practical application effectiveness. Although researchers have developed various modification strategies to improve their photocatalytic performance, research on their application in the photocatalytic activation of C-Cl bonds remains scarce. Recently, there have been a few reports on heterogeneous photocatalytic activation of C-Cl bonds to induce self-coupling and generate pharmacologically active bibenzyl compounds and their derivatives. Angew. Chem. Int. Ed. 2023, 62 , e202307907.; ACS Catal. 2021, 11 , 4338-4348.; Green Chemistry 2022, 24(7622-7629). However, the above reports are often limited to ultraviolet light-driven and relatively simple photocatalytic reduction half-reactions. Therefore, developing an efficient photo-redox system driven by visible light, which can integrate reduction and oxidation half-reactions into a single photo-redox system, is of great significance for constructing high-value-added drug molecules. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method with highly efficient charge separation capabilities and multifunctional active sites (Cu⁺ / Cu). 0 The preparation method and application of photochromic materials (Ovs) were also discussed. Furthermore, a complete photocatalytic oxidation and reduction reaction in a single reaction system was achieved, enabling the synthesis of high-value-added drug molecules through the activation and functionalization of C-Cl bonds.

[0005] A method for preparing a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation is as follows: Ti(OC2H5)4 was added to ethylene glycol and stirred at room temperature until it was evenly dispersed. Then, a certain volume of hydrazine hydrate was added to it. After stirring continuously at room temperature until homogeneous, a certain amount of copper chloride (CuCl2·H2O) is added. After it is completely dissolved, the mixture is transferred to a stainless steel autoclave lined with polytetrafluoroethylene for hydrothermal treatment. After naturally cooling to room temperature, the precipitate was collected by centrifugation, washed with acetone, and dried in a vacuum drying oven. The resulting sample was copper-doped titanium dioxide (Cu-TiO2).

[0006] According to a preferred embodiment of the present invention, the copper source used in the above steps is copper chloride pentahydrate (CuCl2·5H2O).

[0007] According to a preferred embodiment of the present invention, the molar ratio of copper to titanium is 1-6%.

[0008] According to a preferred embodiment of the present invention, the titanium source is tetraethyl titanate.

[0009] According to a preferred embodiment of the present invention, the amount of the reaction solvent ethylene glycol is 30-50 ml.

[0010] According to a preferred embodiment of the present invention, the solvothermal reaction time is 180-200 °C and the solvothermal reaction time is 20-24 h.

[0011] According to a preferred embodiment of the present invention, the washing is performed by centrifugation using acetone solvent, and the temperature of the vacuum drying oven is set to 50-70 °C.

[0012] According to the present invention, the preparation method of the multi-active-site photochromic material and its application in C-Cl bond activation and functionalization transformation can realize the photocatalytic synthesis of high-value-added drug molecules.

[0013] Unique photochromic properties and efficient charge separation mechanism enable the preparation of Cu-based materials via a solvothermal method. 2+ Ion-doped catalyst with Ovs. Under illumination, it exhibits Cu²⁺→Cu⁺ / Cu. 0 The reversible color change, accompanied by a shift from light green to bright red, reflects the efficient capture and utilization of photogenerated electrons. Cu doping significantly improves charge separation efficiency: the photocurrent density is about 3 times higher than that of pure TiO2, the electrochemical impedance is reduced, and the excited-state Cu-TiO2 catalyst further reduces the recombination of photogenerated carriers and surface resistance.

[0014] The photocatalyst exhibits high efficiency and stability. Under visible light (405 nm LED) irradiation, a typical Cu-TiO2 nanocatalyst can efficiently activate benzyl chloride (BnCl) and generate highly selective self-coupling products, with a bibenzyl chloride yield of 96-99%, significantly superior to existing technologies (such as only 3-5% yield with pure TiO2 and only 20-23% yield with physically mixed CuCl2 / TiO2). The catalyst retains over 90% catalytic activity after 29-30 days of continuous use, and the bibenzyl chloride yield does not significantly decrease after 5-6 cycles. XRD confirms that the crystal structure remains unchanged before and after the reaction, and gram-scale experiments verify its industrialization potential.

[0015] By controlling reaction conditions, 4-benzyloxyphenol (monobenzan, 60% yield) and benzylated 1,4-benzoquinone (54% yield), both with pharmaceutical value, can be selectively synthesized, providing an efficient pathway for drug molecule synthesis. Monobenzan has multiple applications in the medical and chemical industries; it is a potent skin bleaching agent used to treat melanoma patients and is also used to induce animal models of skin diseases. As for benzylated 1,4-benzoquinone, it is a monoamine oxidase (MAO) inhibitor used clinically to treat major depressive disorder and Parkinson's disease. Attached Figure Description

[0016] Figure 1 X-ray diffraction (XRD) images of Cu-TiO2 materials with different copper doping ratios containing oxygen vacancies and exhibiting photochromic properties, prepared as examples.

[0017] Figure 2 The photochromic material prepared for the example contains 6% Cu 2+ Transmission electron microscopy (TEM) images of doped TiO2: (a, c) and particle size distribution statistics (b, d).

[0018] Figure 3 The photochromic material prepared in the examples is 6% Cu 2+ Elemental mapping (EDS) image of doped TiO2.

[0019] Figure 4 The initial state and excited state of the photochromic material prepared for the example are 6% Cu. 2+ Electron spin resonance (ESR) spectrum of doped TiO2 photochromic material.

[0020] Figure 5 The photochromic material prepared for the example contains 6% Cu 2+ The full X-ray photoelectron spectroscopy (XPS) spectrum of pure TiO2 in the comparative example of doped TiO2.

[0021] Figure 6 The photochromic material prepared for the example contains 6% Cu 2+ Doped TiO2 and pure TiO2 prepared in the comparative example, as well as 6% Cu in the excited state. 2+ X-ray photoelectron spectroscopy (XPS) Cu 2p spectrum of doped TiO2.

[0022] Figure 7 The photochromic material prepared for the example contains 6% Cu 2+ Doped TiO2 and pure TiO2 prepared in the comparative example, as well as 6% Cu in the excited state. 2+ X-ray photoelectron spectroscopy (XPS) O 1s spectrum of doped TiO2.

[0023] Figure 8 The photochromic material prepared for the example contains 6% Cu 2+ UV spectra of doped TiO2 and its color change under nitrogen conditions with 405 nm LED excitation (a) and its fading after the addition of benzyl chloride (b).

[0024] Figure 9 The figure shows the yield and selectivity of the photochromic material prepared in the example, under the optimal reaction conditions of Cu-doped TiO2 with different doping ratios, for the catalytic dechlorination and self-coupling of benzyl chloride to bibenzyl chloride.

[0025] Figure 10 The photochromic material prepared for the example contains 6% Cu 2+ Stability test diagram of the self-coupling of benzyl chloride to bibenzyl chloride catalyzed under optimal reaction conditions of doped TiO2.

[0026] Figure 11 The photochromic material prepared for the example contains 6% Cu 2+ Photocatalytic synthesis of bibenzyl from doped TiO2 under standard conditions1 H NMR.

[0027] Figure 12 The photochromic material prepared for the example contains 6% Cu 2+ A schematic diagram of DFT calculations for the photocatalytic synthesis of bibenzyl from doped TiO2 under standard conditions.

[0028] Figure 13 Photocurrent spectra of Cu-doped TiO2 with different doping ratios prepared for the example.

[0029] Figure 14 The photochromic materials prepared for the examples include Cu-doped TiO2 with different doping ratios and excited-state 6% Cu. 2 + Impedance diagram of doped TiO2.

[0030] Figure 15 The photochromic material prepared for the example contains 6% Cu 2+ Statistical graph of the yield of photocatalytic synthesis of bibenzyl with doped TiO2 under the addition of various active substance scavengers.

[0031] Figure 16 The photochromic material prepared for the example contains 6% Cu 2+ A schematic diagram illustrating the controllable synthesis of different drug molecules using doped TiO2 under different solvent reaction conditions.

[0032] Figure 17 The photochromic material prepared for the example contains 6% Cu 2+ TiO2-doped photocatalytic synthesis of the drug Monobenzo 1 H NMR.

[0033] Figure 18 The photochromic material prepared for the example contains 6% Cu 2+ Photocatalytic synthesis of the drug benzylated 1,4-benzoquinone using doped TiO2 1 H NMR. Detailed Implementation

[0034] The present invention will be further described below with reference to specific embodiments and accompanying drawings, but is not limited thereto.

[0035] In addition, the experimental methods described in the following embodiments are conventional methods unless otherwise specified; the reagents and materials described are commercially available unless otherwise specified. Example

[0036] A method for preparing a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation is as follows: Add 1 ml of tetraethyl titanate to 33 ml of ethylene glycol solution, stir well, then add 3.3 ml of hydrazine hydrate solution, and continue stirring until the solution is homogeneous. Then add copper chloride pentahydrate with a Ti to Cu molar ratio of 6%, and stir for 30 minutes to obtain a mixed solution.

[0037] The mixed solution from step (1) was transferred to a 50 mL polytetrafluoroethylene reactor and reacted at 200 °C for 24 hours. After the reaction was completed, it was allowed to cool naturally to room temperature.

[0038] The reaction solution obtained in step (2) was filtered, and the precipitate was washed three times by centrifugation with acetone solvent. It was then dried at 60°C for 12 hours to obtain a photocatalyst with photochromic properties.

[0039] The XRD pattern of the 6Cu-TiO2 prepared in this embodiment is shown below. Figure 1 As shown, the composition and phase purity of the sample were characterized. The XRD diffraction peaks of 6Cu-TiO2 correspond to the standard card JCPDS no. 21-1272, indicating that Cu is lattice-doped in TiO2 with no other impurity phases. Figure 2 The 6Cu-TiO2 sample was found to consist of elongated nanoparticles, approximately 21 nm in length and 11 nm in width. Energy-dispersive spectroscopy (EDS) results indicated the presence of copper (Cu), titanium (Ti), and oxygen (O) elements in typical 6Cu-TiO2 nanoparticles. Figure 3 This also proves the successful doping of Cu.

[0040] Figure 4 The electron spin resonance (ESR) spectrum shows that typical 6Cu-TiO2 nanoparticles exhibit strong Cu... 2+ signal (g) ⊥ = 2.05, g ‖ = 2.27), further proving the presence of Cu in TiO2 nanoparticles. 2+ Ion doping. And after illumination, Cu 2+ The signal strength decreased significantly, indicating that Cu 2+ It was reduced to a low price by Guang Sheng Electronics. Figure 5 The XPS full spectrum of the samples prepared for the examples and comparative examples is shown in the figure. Compared with the TiO2 full spectrum, 6% Cu 2+ In addition to Ti, O, and C, the XPS full spectrum of TiO2 doped with Cu also showed Cu, with each element exhibiting a different peak position in the spectrum, which verifies that Cu... 2+ The successful introduction of effective doping of TiO2.

[0041] Figure 6The image shows the 2p XPS spectrum of Cu, with two distinct Cu 2p peaks at binding energies of 951.4 eV and 931.8 eV. 1 / 2 and 2p 3 / 2 A peak is observed, and a vibrational satellite peak is present at 943.6 eV, indicating the presence of Cu. 2+ The Cu 2p peak can be decomposed into Cu... + / Cu 0 (931.8 and 951.4 eV) and Cu 2+ (934.0 and 953.7 eV). Furthermore, after photoexcitation, the 2p peaks and vibrational satellite peaks of Cu at 953.7 and 934.0 eV completely disappeared. And, belonging to Cu... + / Cu 0 The 2p peak of Cu shifted to a lower binding energy by 0.23 eV after illumination, indicating that after illumination, Cu... 2+ Completely reduced to Cu by photogenerated electrons + With Cu 0 .

[0042] like Figure 7 As shown, the XPS spectrum of O 1s in TiO2 exhibits four peaks at 528.9, 529.8, 530.9, and 532.1 eV, corresponding to Ti-O, Ti-OC, surface Ti-OH, and surface oxygen vacancies (Ovs), respectively. Due to Cu doping, the binding energy of O 1s was observed to increase by approximately 0.24 eV in XPS measurements, while the Ovs content increased from 2.4% to 3.6%. After phototreatment, the binding energy of the O 1s XPS peak decreased by 0.2 eV, indicating the formation of Ti³⁺ species and oxygen vacancies. Furthermore, calculations revealed that the oxygen vacancy content in the nanoparticles increased from 3.6% to 5.0%.

[0043] When the 6Cu-TiO2 photocatalyst with photochromic properties prepared in this embodiment is dispersed in an isopropanol-water (1:1) solution, it exhibits unique photochromic behavior under blue LED irradiation, with its color gradually changing from an initial light green (static state) to a bright red (activated state). Correspondingly, under illumination, the absorption intensity of the UV-Vis absorption spectrum of the dispersion gradually increases in the 375-780 nm range. Figure 8 It exhibits two characteristic absorption peaks at 445 nm and 575 nm, corresponding to Cu, respectively. + and Cu 0 Speciation. When benzyl chloride is added to an activated Cu-TiO2 nanoparticle dispersion, its bright red color fades. Figure 8This phenomenon indicates that 6Cu-TiO2 nanoparticles in the activated state can capture photogenerated electrons and transfer them to benzyl chloride molecules, thus providing a possibility for photoinduced C-Cl bond reduction reactions.

[0044] Figure 9 The figure shows the yield and selectivity statistics of the self-coupling of benzyl chloride to bibenzyl chloride under the optimal reaction conditions of Cu-doped TiO2 with different doping ratios for the photochromic materials prepared in the examples. As shown in the figure, the activity and selectivity of the benzyl chloride dehalogenation coupling reaction are significantly improved with the increase of copper doping. When the copper doping reaches 6% (6Cu-TiO2 nanoparticles), a bibenzyl chloride yield of up to 96% and a selectivity of over 99% can be obtained after 10 hours of reaction. However, excessive copper doping leads to a decrease in yield, which may be due to: 1) excessive dopant may become an electron-hole recombination center; 2) excessive coverage of copper species on the surface, thereby reducing the charge carrier concentration available for the catalytic reaction.

[0045] Figure 10 The photochromic material prepared for the example contains 6% Cu 2+ The stability test results for the self-coupling of benzyl chloride to bibenzyl chloride under optimal reaction conditions with doped TiO2 are shown. The results indicate that the catalyst retains high reactivity after multiple cycles, demonstrating its good stability.

[0046] Figure 11 The photochromic material prepared for the example contains 6% Cu 2+ Photocatalytic synthesis of bibenzyl from doped TiO2 under standard conditions 1 ¹H NMR was used to confirm that the catalytic yield was 96%. Figure 12 This is a schematic diagram of the DFT calculation results for the activation of the C-Cl bond of benzyl chloride. The calculation system investigated the adsorption performance of benzyl chloride and its key intermediate, benzyl radical, on TiO2 and Cu-TiO2 surfaces. The calculation results show that compared with pure TiO2 nanoparticles, Cu-TiO2 nanoparticles have significantly higher adsorption energies for benzyl chloride (-0.012 eV and -0.022 eV, respectively), which confirms that benzyl chloride is more readily adsorbed onto copper ions through coordination. More importantly, the adsorption energy of benzyl radical on the Cu-TiO2 surface (-2.17 eV) is significantly higher than that on the pure TiO2 surface (-1.92 eV), fully demonstrating that Cu-TiO2 can effectively stabilize surface benzyl radicals, a characteristic that is crucial for subsequent coupling reactions.

[0047] Figure 13 and 14The photocurrent and impedance spectra of Cu-doped TiO2 with different doping ratios prepared for the example are shown. This demonstrates that Cu doping significantly improves the photoelectric separation efficiency of single TiO2 and reduces the surface resistance of the catalyst. Furthermore, the surface resistance of the catalyst in the excited state is further reduced, giving it stronger charge transport capabilities.

[0048] Figure 15 The photochromic material prepared for the example contains 6% Cu 2+ Statistical graphs showing the yield of photocatalytic synthesis of bibenzyl with doped TiO2 under various active scavenging agents. In this study, O2, silver nitrate, and KI were used as electron (e⁻) and hole (h⁺) scavengers, respectively, for quenching experiments. The results showed that the yield of bibenzyl was unaffected by the addition of the hole scavenger KI; however, the yield decreased to 15% in the presence of O2, confirming that O2 acts as an exogenous electron acceptor competing with the reaction system for electrons. Notably, when silver nitrate was used to capture photogenerated electrons, the formation of bibenzyl was completely suppressed, fully demonstrating the crucial role of photogenerated electrons in the reduction reaction.

[0049] Figure 16 The photochromic material prepared for the example contains 6% Cu 2+ A schematic diagram illustrating the controllable synthesis of different drug molecules using doped TiO2 under varying solvent reaction conditions. While photogenerated electrons and holes possess excellent reduction and oxidation capabilities in photocatalysis, research on how to synergistically utilize them to drive oxidation and reduction reactions within the same system remains scarce. Based on the highly efficient photoreduction performance of Cu-TiO2 photocatalysts for benzyl chloride, we successfully constructed a synergistic photoredox system, achieving the selective synthesis of CC and CO bonded drug molecules through coupling with the oxidation half-reaction. To drive the oxidation half-reaction, p-phenol was selected as a valuable raw material. By controlling the reaction solvent, 4-benzyloxyphenol (monobenzoan) and benzylated 1,4-benzoquinone could be selectively synthesized in this photoredox catalytic system. It is particularly noteworthy that 4-benzyloxyphenol has significant applications in the pharmaceutical and chemical industries, serving as a potent skin whitening agent for melanoma treatment and for constructing animal models of skin diseases. Meanwhile, benzylated 1,4-benzoquinone, as a monoamine oxidase (MAO) inhibitor, is clinically used to treat major depressive disorder and Parkinson's disease. The successful synthesis of the two drugs also Figure 17 and 18 of 1 Confirmed by H NMR.

[0050] As described in Example 1, under the same conditions, the amount of copper chloride was changed so that the molar ratio of doped Cu was 1, 3 and 10%, and several Cu-TiO2 with different doping ratios were prepared.

[0051] Commercially available TiO2 with the same crystal form was used as a comparison sample.

[0052] The catalysts prepared in the above examples were subjected to experiments, and the steps are as follows: 10-15 mg of 6Cu-TiO2 from Example 1 was dispersed in 2.5-3.5 mL of a mixed solvent (water:isopropanol = 1:1) containing benzyl chloride (0.05-0.15 mmol), and twice the equivalent amount of potassium carbonate was added to the reaction system. Before the photocatalytic reaction, to ensure the removal of oxygen from the reaction tube, the air was purged with nitrogen and then sealed with a sealing film. Subsequently, the photocatalytic reaction was carried out under blue light (405 nm, 100 W), and the reaction environment was controlled at 30-35 °C (room temperature) using a constant-temperature water pump. The light source was positioned 1-1.5 cm away from the quartz tube. After reacting at room temperature for 10-12 h, trimethoxybenzene was added as an internal standard for calibration. The suspension was collected, centrifuged, extracted, and quantitatively analyzed using GC-MS.

[0053] 10-15 mg of Cu-TiO2 nanocatalyst was dispersed in 3-4 mL of a mixed solvent (isopropanol:water = 1:1) or 3-4 mL of acetonitrile, and 0.05-0.15 mmol of benzyl chloride, 0.4-0.6 mmol of p-phenol, and 0.1-0.3 mmol of potassium carbonate were added. Under a nitrogen (N2) atmosphere, the mixture was placed under a 405 nm LED light source and stirred at room temperature for 10-15 hours. After the reaction was complete, the mixture was diluted with water and extracted with dichloromethane. The extract was concentrated by vacuum distillation and then purified by silica gel column chromatography (eluent: ethyl acetate / n-hexane), and the yield was calculated.

[0054] This study developed a photochromic Cu-TiO2 nanocatalyst, achieving synergistic catalysis of C-Cl bond activation and p-phenol oxidation under visible light-driven conditions. This catalyst utilizes Cu²⁺ and Cu⁺ / Cu... 0 The reversible enhancement of charge separation between the active sites of benzyl chloride and its active sites can simultaneously mediate the dechlorination reduction and radical coupling of benzyl chloride, achieving highly selective synthesis of bibenzyl chloride (yield 96%, selectivity >99%). By controlling the solvent, high-value-added drug molecules such as CO bonds (monobenzene) or C / C bonds (benzylated 1,4-benzoquinone) can be selectively obtained. This work provides a new strategy for designing multifunctional photocatalysts, promoting green drug synthesis.

Claims

1. A method for preparing a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation is as follows: (1) Add tetraethyl titanate to ethylene glycol solution, stir evenly, then add hydrazine hydrate solution, continue stirring until the solution is uniform, then add copper chloride pentahydrate, stir for 30 minutes to obtain mixed solution; (2) After continuous stirring at room temperature, the mixture is transferred to a stainless steel autoclave lined with polytetrafluoroethylene for hydrothermal treatment; (3) After naturally cooling to room temperature, the precipitate was collected by centrifugation, washed with acetone, and dried in a vacuum drying oven. The sample Cu-TiO2 was obtained.

2. The preparation method of Cu-TiO2, a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation according to claim 1, is characterized in that, The copper chloride hydrate mentioned is copper chloride pentahydrate, and the order of addition of each reaction raw material is specified.

3. The method for preparing the multi-active-site photochromic catalyst Cu-TiO2 based on C-Cl bond activation and functionalization transformation according to claim 1, characterized in that, The molar ratio of copper source to titanium source is 1% to 10%.

4. The method for preparing the multi-active-site photochromic catalyst Cu-TiO2 based on C-Cl bond activation and functionalization transformation according to claim 1, characterized in that, The volume of the ethylene glycol is 30-50 mL.

5. The method for preparing the multi-active-site photochromic catalyst Cu-TiO2 based on C-Cl bond activation and functionalization transformation according to claim 1, characterized in that, The volume of hydrazine hydrate added was 3.3 ml.

6. The method for preparing the multi-active-site photochromic catalyst Cu-TiO2 based on C-Cl bond activation and functionalization transformation according to claim 1, characterized in that, The solvothermal maintenance temperature is 180~200℃, and the time is 20~24 h.

7. The method for preparing the multi-active-site photochromic catalyst Cu-TiO2 based on C-Cl bond activation and functionalization transformation according to claim 1, characterized in that, The temperature of the drying oven is 50~70℃.

8. The method for preparing Cu-TiO2, a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation according to claim 1, is applied to the selective synthesis of bibenzyl chloride (yield > 95%, selectivity > 99%) by reducing benzyl chloride to benzyl radical under visible light.

9. The method for preparing Cu-TiO2, a multi-active-site photochromic catalyst based on C-Cl bond activation and functionalization transformation according to claim 1, is applied to selectively prepare monobenzene or benzylated 1,4-benzoquinone under visible light by controlling the solvent to be acetonitrile or a mixture of water and isopropanol and in the presence of potassium carbonate.

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