Metalloporphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reaction as well as preparation method and application of metalloporphyrin / carbon nanotube composite catalyst

Abstract

The invention discloses a metalloporphyrin / carbon nanotube composite catalyst for an organic phase electrochemical oxygen transfer reaction as well as a preparation method and application of the metalloporphyrin / carbon nanotube composite catalyst. The preparation method comprises the following steps: providing ligand modified metalloporphyrin; wherein the ligand modified metalloporphyrin has a hydrophilic functional group and / or a hydrophobic functional group; and dispersing the ligand modified metalloporphyrin and a hydroxylated carbon nanotube in an organic solvent, and carrying out a reaction so as to prepare the metalloporphyrin / carbon nanotube composite catalyst. The metalloporphyrin / carbon nanotube composite catalyst provided by the invention is stable in structure, the problem of degradation of a traditional homogeneous porphyrin molecular catalyst is avoided in electrochemical reaction, the generation efficiency of a high-valence metal-oxygen species intermediate is remarkably improved, the turnover frequency of the reaction reaches up to 171 s, and the Faraday efficiency exceeds 99%.

Description

Technical Field

[0001] This invention belongs to the field of oxygen atom transfer reaction technology, specifically relating to a metal porphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reactions, its preparation method and application. Background Technology

[0002] Most organic oxidation reactions rely on the participation of chemical oxidants to overcome the thermodynamically unfavorable dehydrogenation or dehydrogenation coupling reactions during oxidation. In the prior art, oxygen atom transfer reactions offer a more attractive alternative. This process typically involves a direct reaction between high-valence metal-oxygen species and the lone pair electrons of the substrate, avoiding the thermodynamically unfavorable dehydrogenation process and promising highly selective oxidative transformations.

[0003] Currently, the high-valence metal oxide intermediates commonly used rely on oxygen sources such as hydrogen peroxide and organic peroxides. However, these oxygen sources have low molecular utilization rates, are difficult to regenerate, and the reaction conditions are usually very harsh (inert atmosphere, high temperature reaction, etc.), and are often accompanied by the generation of toxic byproducts, which limits their widespread application.

[0004] Similar high-valence metal-oxygen species can also be obtained by electrochemical methods. Existing literature shows that metalloporphyrin molecules with structures similar to natural enzymes exhibit good activity in homogeneous electrocatalytic oxygen atom transfer reactions. However, due to the easy generation of strong oxidizing intermediates (such as hydroxyl radicals) during the reaction, the porphyrin molecular structure is easily destroyed and metal ions are lost, which affects the stability and lifetime of the catalytic reaction. Special axial ligands and sacrificial agents are usually designed, as well as high catalyst concentrations to maintain the stability of homogeneous porphyrin catalysts in oxygen atom transfer reactions. Currently, the homogeneous metalloporphyrin electrocatalytic system used for oxygen atom transfer reactions has the following prominent problems: (1) Unstable material structure: Traditional homogeneous metalloporphyrins are easily degraded under electrocatalytic conditions, making it difficult to maintain effective active centers; (2) Lack of interface regulation: There is a lack of stable interaction interface between the molecular catalyst and the electrode, resulting in low efficiency of electron transport and intermediate transfer; (3) The homogeneous catalytic system is complex, and catalyst recovery is difficult. Summary of the Invention

[0005] The main objective of this invention is to provide a metal porphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reactions, its preparation method and application, so as to overcome the problems of poor stability, low oxygen source utilization efficiency and poor selectivity of molecular catalysts under electrolysis conditions in the prior art.

[0006] To achieve the aforementioned objectives, the technical solution adopted by this invention includes: This invention provides a method for preparing a metal porphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reactions, comprising: Provided ligand-modified metalloporphyrins; wherein the ligand-modified metalloporphyrins have hydrophilic and / or hydrophobic functional groups; Furthermore, the ligand-modified metalloporphyrin and hydroxylated carbon nanotubes are dispersed in an organic solvent and reacted to obtain a metalloporphyrin / carbon nanotube composite catalyst. The ligand-modified metalloporphyrin has a structure as shown in formula (I): Formula (I) In equation (I), Ar is selected from any of the following structures: ; The metal M in formula (I) is selected from Mn, Fe, Co or Ni.

[0007] The present invention also provides a metalloporphyrin / carbon nanotube composite catalyst prepared by the aforementioned preparation method.

[0008] The embodiments of the present invention also provide the use of the aforementioned metal porphyrin / carbon nanotube composite catalyst in electrocatalytic oxygen atom transfer reactions.

[0009] This invention also provides a method for preparing sulfoxides by selective oxidation of sulfides via electrocatalytic oxygen atom transfer, comprising: The aforementioned metal porphyrin / carbon nanotube composite catalyst is provided; Using the aforementioned metal porphyrin / carbon nanotube composite catalyst as the anode catalyst and water as the oxygen source, the sulfoxide substrate is electrocatalyzed in an organic electrolyte system under constant potential or constant current conditions to produce the sulfoxide product.

[0010] Compared with the prior art, the beneficial effects of the present invention are as follows: (1) The metal porphyrin / carbon nanotube composite catalyst provided by this invention has a stable structure, avoids the degradation problem of traditional homogeneous porphyrin molecular catalysts in electrochemical reactions, and significantly improves the generation efficiency of high-valence metal-oxygen species intermediates, with a reaction turnover frequency as high as 171 s. -1 The Faraday efficiency exceeds 99%, which is one of the highest levels reported in the literature to date. (2) By introducing ligand electronic regulation and interface hydrophilicity design, this invention constructs a single-molecule catalytic site with an electron-deficient center and a hydrophilic microenvironment, realizing a highly selective oxygen atom transfer reaction with water as the oxygen source in an organic electrolyte system. It is suitable for a variety of functionalized substrates, with short reaction time and strong selectivity. No sacrificial agent or excess oxidant is required, and the reaction system is green and environmentally friendly. (3) The synthesis method of the metal porphyrin / carbon nanotube composite catalyst in this invention is simple to operate, can be prepared on a large scale, and can be stably operated for more than 54 hours under continuous reaction conditions, realizing the gram-level preparation of methylbenzene sulfoxide, and has good prospects for industrial scale-up. (4) This invention provides a generalizable material design strategy for constructing a stable and efficient molecular heterogeneous electrocatalyst (metal porphyrin / carbon nanotube composite catalyst) system, and opens up a new path for green and efficient electrocatalytic oxidation reactions in organic synthesis. Attached Figure Description

[0011] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0012] Figure 1 This is a high-resolution transmission electron microscope (HRTEM) image of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst obtained in Example 1 of the present invention. Figure 2 This is a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst obtained in Example 1 of this invention. Figure 3 The X-ray absorption near-edge structure (XANES) spectra of the Mn K-edge of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst and its comparative material obtained in Example 1 of this invention are shown. Figure 4 The extended X-ray absorption fine structure (EXAFS) spectra of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst and its comparative material obtained in Example 1 of this invention are shown. Figure 5 The LSV curves of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst and its comparative materials obtained in Example 1 of this invention are shown. Figure 6 This is the current-time curve diagram in Embodiment 1 of the present invention; Figure 7 This is a graph showing the conversion rate-time of anisole in Example 1 of the present invention. Figure 8This is a cell pressure-time curve diagram from Embodiment 2 of the present invention; Figure 9 This is a graph showing the conversion rate-time of anisole in Example 2 of the present invention. Figure 10 The 1H NMR spectrum (400 MHz) of omeprazole, the product in Example 8 of this invention. Figure 11 The proton NMR spectrum (400 MHz) of albendazole sulfoxide, the product of Example 9 of this invention. Figure 12 This is a cell pressure-time curve of a gram-level reaction that was continuously run for 54 hours in Example 10 of the present invention. Detailed Implementation

[0013] In view of the deficiencies of the prior art, the inventors of this case, through long-term research and extensive practice, have proposed the technical solution of this invention. The technical solution of this invention will be clearly and completely described below. Obviously, the described embodiments are only some, not all, of the embodiments of this invention. All other embodiments obtained by those skilled in the art based on the embodiments of this invention without creative effort are within the scope of protection of this invention.

[0014] Specifically, as one aspect of the technical solution of this invention, a method for preparing a metal porphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reaction includes: Provided ligand-modified metalloporphyrins; wherein the ligand-modified metalloporphyrins have hydrophilic and / or hydrophobic functional groups; Furthermore, the ligand-modified metalloporphyrin and hydroxylated carbon nanotubes are dispersed in an organic solvent and reacted to obtain a metalloporphyrin / carbon nanotube composite catalyst. The ligand-modified metalloporphyrin has a structure as shown in formula (I): Formula (I) In equation (I), Ar is selected from any of the following structures: ; The metal M in formula (I) is selected from Mn, Fe, Co or Ni.

[0015] In some preferred embodiments, the ligand-modified metalloporphyrin has hydrophilic and electron-withdrawing functional groups.

[0016] In some preferred embodiments, Ar in formula (I) is selected from .

[0017] In some preferred embodiments, the metal M in formula (I) is selected from Mn.

[0018] In some preferred embodiments, the preparation method specifically includes: dispersing, sonicating, and stirring the ligand-modified metalloporphyrin and hydroxylated carbon nanotubes in an organic solvent, followed by washing and drying to obtain a metalloporphyrin / carbon nanotube composite catalyst.

[0019] Furthermore, the mass ratio of the ligand-modified metalloporphyrin to the hydroxylated carbon nanotubes is 1:20 to 1:50; Furthermore, the ultrasound uses a power of 150~900W and a duration of 1~2 hours.

[0020] Furthermore, the stirring process employs a stirring rate of 500~1000 rpm for a duration of 24~48 h.

[0021] In some preferred embodiments, the ligand-modified metalloporphyrin includes 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese.

[0022] In some embodiments, the composite catalyst is constructed using a "surface anchoring-ligand modification" strategy. Specifically, the preparation method includes: ultrasonically dispersing and stirring a hydroxylated carbon nanotube and a ligand-modified metalloporphyrin solution in N,N-dimethylformamide, achieving composite loading through electrostatic interactions and π-π stacking. The resulting solid material is then washed and dried to obtain the metalloporphyrin / hydroxylated carbon nanotube composite catalyst. The mass ratio of metalloporphyrin to carbon nanotubes is 1:20 to 1:50, the ultrasonic dispersion time is preferably 2 hours, and the stirring loading time is 24 hours.

[0023] In some embodiments, the metalloporphyrin uses 5,10,15,20-tetraphenylporphyrin manganese as the basic framework and modifies it by introducing ligands with different electronic effects and hydrophilic / hydrophobic functional groups to regulate the electronic structure of the metal center and the hydrophilicity of the reaction interface; among them, the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite material exhibits the best performance in this invention.

[0024] Another aspect of the present invention provides a metalloporphyrin / carbon nanotube composite catalyst prepared by the aforementioned preparation method.

[0025] The metal porphyrin / carbon nanotube composite catalyst in this invention is a molecular heterogeneous electrocatalyst.

[0026] Another aspect of the present invention provides the use of the aforementioned metal porphyrin / carbon nanotube composite catalyst in electrocatalytic oxygen atom transfer reactions.

[0027] For example, the application of metalloporphyrin / carbon nanotube composite catalysts in oxygen atom transfer reactions that selectively oxidize sulfides to sulfoxides using water as an oxygen source under anodic conditions. Specifically, this metalloporphyrin / carbon nanotube composite catalyst can effectively catalyze the selective conversion of a series of sulfide substrates to sulfoxides with a Faradaic efficiency exceeding 99%, making it suitable for the synthesis of drug intermediates and gram-scale continuous conversions.

[0028] Another aspect of the present invention provides a method for preparing sulfoxides by selective oxidation of sulfides via electrocatalytic oxygen atom transfer, comprising: The aforementioned metal porphyrin / carbon nanotube composite catalyst is provided; Using the aforementioned metal porphyrin / carbon nanotube composite catalyst as the anode catalyst and water as the oxygen source, the sulfoxide substrate is electrocatalyzed in an organic electrolyte system under constant potential or constant current conditions to produce the sulfoxide product.

[0029] In some preferred embodiments, the method specifically includes: applying the metal porphyrin / carbon nanotube composite catalyst to conductive carbon paper as the anode working electrode, using an organic solvent-water system as the electrolyte, and then adding an electrolyte to catalyze the electrocatalytic oxidation reaction of the sulfide substrate.

[0030] Furthermore, the loading of the metal porphyrin / carbon nanotube composite catalyst in the anode working electrode is 0.1~2 mg / cm², for example 1 mg / cm².

[0031] Furthermore, the volume ratio of organic solvent to water in the electrolyte is (1:1) to (50:1), for example, 10:1.

[0032] Furthermore, the organic solvent is a water-miscible organic solvent, including any one or more combinations of acetonitrile, tetrahydrofuran, dioxane, and acetone, and is not limited thereto.

[0033] Furthermore, the electrolyte includes any one or more combinations of tetrabutylammonium hexafluorophosphate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium perchlorate, tetrabutylammonium bromide, and sodium perchlorate, and is not limited thereto.

[0034] Furthermore, the thioether substrate includes aryl thioether substrates and / or aliphatic thioether substrates.

[0035] Furthermore, the sulfide substrate includes any one or more combinations of anisole, p-chloroanisole, 4-methoxyanisole, 2-(methylthio)pyridine, dibenzothiophene, dibutyl sulfide, and omeprazole sulfide, and is not limited thereto.

[0036] In some preferred embodiments, the electrocatalytic oxidation reaction is carried out at a voltage of 0.5~1.0V (vs Fc / Fc). + The reaction temperature is 20~60℃, and the current density is controlled at 50mA / cm. 2 Within.

[0037] In some embodiments, the resulting composite catalyst is coated onto conductive carbon paper at a loading of 1 mg / cm² and used as the anolyte in an electrocatalytic oxygen atom transfer reaction. The electrolyte is an acetonitrile-water system, preferably with a volume ratio of 10:1, and a supporting electrolyte, tetrabutylammonium hexafluorophosphate, is added at a concentration preferably 0.25 M.

[0038] In some more preferred embodiments, the sulfide substrate is anisole, and its electrocatalytic oxidation reaction voltage range is 0.5–1.0 V (vs Fc / Fc). + The reaction temperature is 20–60℃, and the current density is controlled at 50 mA / cm². 2 Within a certain range, the reaction time is 0.5 to 54 hours.

[0039] The method is widely applicable to structurally diverse aryl and aliphatic thioether substrates, and the resulting sulfoxide products can be quantitatively analyzed and structurally confirmed by methods such as proton nuclear magnetic resonance spectroscopy.

[0040] This invention presents a metalloporphyrin / carbon nanotube composite catalyst constructed based on a "surface anchoring-ligand modification" strategy, and applies it to an oxygen atom transfer reaction that selectively oxidizes sulfides to sulfoxides under anodic conditions using water as the oxygen source. The method includes: anchoring a ligand-modified metalloporphyrin molecular catalyst on the surface of hydroxylated carbon nanotubes, and then electrocatalytically oxidizing sulfide substrates under electrochemical conditions to generate the corresponding sulfoxide products.

[0041] In some implementations, the method specifically includes: An electrolyte containing a sulfide substrate, water, and an electrolyte is provided and added to the electrochemical reactor; The catalyst formed by loading ligand-modified metalloporphyrins onto hydroxylated carbon nanotubes is modified onto the working electrode. Under constant current or constant potential conditions, an electrolytic reaction is carried out to selectively oxidize the substrate to sulfoxides and avoid the formation of byproducts (sulfones).

[0042] In some embodiments, the method for constructing the metalloporphyrin / carbon nanotube composite catalyst includes: dispersing hydroxylated carbon nanotubes and metalloporphyrins modified with different ligands in an organic solvent, ultrasonicating and stirring to form a stable composite through electrostatic interactions and π-π interactions, and then washing and drying to obtain the metalloporphyrin / carbon nanotube composite catalyst. The ligands regulate the electron density and microenvironment of the metal center by introducing electron-withdrawing and / or hydrophilic groups.

[0043] The technical solution of the present invention will be further described in detail below with reference to several preferred embodiments and accompanying drawings. This embodiment is implemented on the premise of the technical solution of the invention, and provides detailed implementation methods and specific operation processes. However, the protection scope of the present invention is not limited to the following embodiments.

[0044] Unless otherwise specified, the experimental materials used in the examples below can be purchased from conventional biochemical reagent companies.

[0045] Example 1 Assembly of manganese porphyrin molecular catalyst supported on hydroxylated carbon nanotubes and its application in a membraneless electrolytic cell for the electrocatalytic oxidation of benzyl sulfide to sulfoxide.

[0046] Measure 30 mg of commercially available hydroxylated multi-walled carbon nanotubes (purchased from XFNANO) and add them to 20 mL of N,N-dimethylformamide (DMF, HPLC grade). Disperse the mixture by sonication for 60 minutes. Separately, weigh 1.5 mg of 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese and dissolve it in 10 mL of DMF. Sonicate the solution by sonication for 60 minutes. Combine the two dispersions and sonicate for another 60 minutes. Then, stir the mixture at 700 rpm at room temperature for 24 hours using a magnetic stirrer to promote uniform anchoring of manganese porphyrin on the carbon nanotube surface.

[0047] After the mixing reaction was completed, the precipitate was collected by centrifugation at 12,000 rpm for 5 minutes and washed three times each with DMF, ultrapure water, and ethanol. The precipitate was then vacuum-dried overnight to obtain a catalyst with 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin manganese supported on carbon nanotubes (i.e., manganese porphyrin / carbon nanotube composite catalyst). 10 mg of the prepared catalyst was added to a mixture of 950 μL isopropanol and 50 μL DuPont membrane solution (5 wt.%) and ultrasonically dispersed for 2 hours to obtain a homogeneous catalyst ink. 100 μL of this catalyst ink was dropped onto a 1 cm² piece of conductive carbon paper using a pipette. After drying, the working electrode was obtained, with a catalyst loading of 1 mg / cm².

[0048] Electrocatalytic assays were performed using a membraneless electrolytic cell system at 25 °C with stirring at 500 rpm. The electrolyte was acetonitrile:water = 10:1 (volume ratio), with 0.25 M tetrabutylammonium hexafluorophosphate added as the supporting electrolyte. The substrate was 1 mmol of anisole. The catalytic reaction was carried out at a current density of 10 mA / cm². 2 Run for 3 hours under constant current conditions.

[0049] After the reaction was complete, 50 μL of the reaction solution was sampled and mixed with 550 μL of deuterated chloroform (containing 0.03% TMS). The reaction products were detected by 1H NMR spectroscopy (400 MHz). The yield of the target product sulfoxide was calculated using the signal of tetrabutylammonium hexafluorophosphate as an internal standard, and it was confirmed that no sulfoxide byproduct was formed.

[0050] Experimental results analysis: This catalyst exhibits highly efficient electrocatalytic oxidation activity. After the reaction, NMR confirmed the formation of benzene sulfoxide, with a conversion rate of 55.6% and a Faraday efficiency of 99.3%. Constant voltage polarization experiments showed that at an operating voltage of 0.6 V (vs Fc / Fc...), the catalyst... + A significant current response was observed immediately, and no byproducts were generated, verifying that the material has excellent oxygen atom transfer catalytic performance and product selectivity.

[0051] Figure 1 High-resolution transmission electron microscopy (HRTEM) images of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst obtained in this embodiment are shown. Figure 2 This image shows a high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) image of the catalyst used in this embodiment. Figure 3 The X-ray absorption near-edge (XANES) spectrum of Mn K-edge is shown, proving that the Mn center in the catalyst is in an electron-deficient state, which is conducive to the formation of high-valence metal-oxygen intermediates; Figure 4 The extended X-ray absorption fine structure (EXAFS) spectra of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst and its comparative material obtained in Example 1 of this invention are shown. Figure 5 The LSV curves of the 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese / hydroxylated carbon nanotube composite catalyst and its comparative materials obtained in this embodiment are shown. Figure 6 This is the current-time curve in this embodiment; Figure 7 This is a graph showing the conversion rate-time of benzyl sulfide in this embodiment.

[0052] Example 2 The same catalyst preparation method, electrode construction, electrochemical reaction conditions, and product detection method as in Example 1 were used, with 1 mmol of anisole as the substrate. The reaction was carried out at a current density of 10 mA / cm². 2 The reaction was conducted at a time of 325 minutes (the reaction time at which the theoretical conversion rate is 100% at this current density). After the reaction, the conversion rate of the target product to benzene sulfoxide was 98% by quantitative detection using nuclear magnetic resonance hydrogen spectroscopy (400 MHz). Figure 8This is the tank pressure-time curve in this embodiment; Figure 9 This is a graph showing the conversion rate-time of benzyl sulfide in this embodiment.

[0053] Example 3 Using the same catalyst preparation method, electrode structure, electrochemical reaction conditions, and product detection method as in Example 2, except that anisole was replaced with p-chlorobenzyl sulfide, the conversion rate of the target product p-chlorobenzyl sulfoxide was 97% after the reaction was completed by quantitative detection using 1H NMR spectroscopy (400 MHz) at the same reaction time and current density.

[0054] Example 4 Using the same catalyst preparation method, electrode structure, electrochemical reaction conditions, and product detection method as in Example 2, only the substrate was replaced with 4-methoxybenzyl sulfide. Under the same reaction time and current density, the conversion rate of the target product, 4-methoxybenzyl sulfoxide, was 93% after the reaction was completed, as quantitatively detected by 1H NMR spectroscopy (400 MHz). No methoxy decomposition was detected under these conditions, indicating that the catalytic system has good functional group tolerance.

[0055] Example 5 Using the same catalyst preparation method, electrode structure, electrochemical reaction conditions, and product detection method as in Example 2, only the substrate was replaced with 2-(methylthio)pyridine. Under the same reaction time and current density, quantitative detection by 1H NMR (400 MHz) after the reaction revealed a conversion rate of 84% for the target product, methyl(2-pyridyl) sulfoxide, indicating that this catalytic system also exhibits high activity for substrates with heterocyclic structures.

[0056] Example 6 Using the same catalyst preparation method, electrode structure, electrochemical reaction conditions, and product detection method as in Example 2, only the substrate was replaced with dibenzothiophene. Under the same reaction time and current density, the conversion rate of the target product diphenyl sulfoxide was found to be 89% by quantitative detection by 1H NMR spectroscopy (400 MHz) after the reaction.

[0057] Example 7 Using the same catalyst preparation method, electrode structure, electrochemical reaction conditions, and product detection method as in Example 2, except that the substrate was replaced with dibutyl sulfoxide, a typical aliphatic sulfoxide, the conversion rate of the target product, dibutyl sulfoxide, was 94% after the reaction was completed, as quantitatively detected by 1H NMR spectroscopy (400 MHz). This result indicates that the catalyst also exhibits good compatibility with substrates without aromatic ring structures.

[0058] Example 8 Using the same catalyst preparation method, electrode structure, and electrochemical reaction conditions as in Example 2, only the substrate was replaced with the drug prodrug omeprazole thioether. The purified product was obtained by rotary evaporation and column chromatography after the reaction, with a yield of 61%. Nuclear magnetic resonance (NMR) 1H (400 MHz) spectroscopy was used (e.g., Figure 10 As shown in the image, and NMR (101 MHz) analysis confirmed the formation of its oxidation product, omeprazole. This result demonstrates the catalyst's practical conversion capability on drug-related substrates.

[0059] Example 9 Using the same catalyst preparation method, electrode structure, and electrochemical reaction conditions as in Example 2, only the substrate was replaced with the drug albendazole. The purified product was obtained by rotary evaporation and column chromatography after the reaction, with a yield of 73%. Nuclear magnetic resonance (NMR) 1H (400 MHz) spectroscopy was used (e.g., Figure 11 As shown in the figure, and nuclear magnetic resonance carbon spectroscopy (101 MHz) analysis confirmed the formation of its oxidation product albendazole sulfoxide (the active ingredient of albendazole).

[0060] Example 10 To verify the continuous operation capability of the material, the same electrode as in Example 1 was used, and the reaction was carried out for 54 hours with a gram-level anisole (1.24 g) substrate. After the electrolysis reaction was completed, 1.37 g of crude anisole sulfoxide was obtained through crude purification, with a yield of 98% and a purity of 95%. The cell pressure-time curve for the gram-level reaction carried out continuously for 54 hours is shown in the figure. Figure 12 As shown, no significant changes in tank pressure were observed throughout the process, indicating that the material exhibited good stability.

[0061] Compare with Example 1 This comparative example is basically the same as Example 1, except that 5,10,15,20-tetra(4-carboxyphenyl)porphyrin manganese is replaced with 5,10,15,20-tetraphenylporphyrin manganese, resulting in a conversion rate of 45.3% and a Faraday efficiency of 80.8%.

[0062] Compare with Example 2 This comparative example is basically the same as Example 1, except that: if the hydroxylated carbon nanotubes are replaced with graphitized carbon nanotubes, no reaction will occur.

[0063] Compare with Example 3 This comparative example uses only 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin manganese as a catalyst, dissolved in an electrolyte (concentration of 1 mM), instead of being supported on hydroxylated carbon nanotubes, and uses uncoated carbon paper as the working electrode. Other experimental conditions in this comparative example are basically the same as in Example 1, under which the reaction cannot occur.

[0064] In addition, the inventors of this case also conducted experiments with other raw materials, process operations, and process conditions described in this specification, referring to the aforementioned embodiments, and obtained relatively ideal results in all cases.

[0065] It should be understood that the technical solutions of the present invention are not limited to the specific embodiments described above. Any technical modifications made to the technical solutions of the present invention without departing from the spirit and scope of the claims are within the scope of protection of the present invention.

Claims

1. A method for preparing a metalloporphyrin / carbon nanotube composite catalyst for organic phase electrochemical oxygen transfer reactions, characterized by, Comprise: Providing ligand-modified metalloporphyrin; wherein the ligand-modified metalloporphyrin has hydrophilic functional groups and / or hydrophobic functional groups; And the ligand-modified metalloporphyrin, hydroxylated carbon nanotubes are dispersed in an organic solvent to react, and a metalloporphyrin / carbon nanotube composite catalyst is prepared; Wherein the ligand-modified metalloporphyrin has a structure as shown in formula (I): Formula (I) Ar in the formula (I) is selected from any one of the following structures: ； The metal M in the formula (I) is selected from Mn, Fe, Co or Ni.

2. The method of claim 1, wherein: The ligand-modified metalloporphyrin has hydrophilic, electron-withdrawing functional groups; and / or, Ar in formula (I) is selected from ; And / or, the metal M in formula (I) is selected from Mn.

3. The production method according to claim 1, characterized by, Specifically comprising: The ligand-modified metalloporphyrin, hydroxylated carbon nanotubes are dispersed, ultrasonic, stirring treatment in an organic solvent, and then washed, dried to prepare a metalloporphyrin / carbon nanotube composite catalyst; Preferably, the mass ratio of the ligand-modified metalloporphyrin to the hydroxylated carbon nanotubes is 1:20-1:50; Preferably, the ultrasonic power is 150~900W, and the time is 1~2 h; preferably, the stirring rate used in the stirring treatment is 500~1000 rpm, and the time is 24~48 h.

4. The preparation method according to claim 1, characterized in that, The ligand-modified metalloporphyrin includes 5,10,15,20-tetrakis(4-carboxyphenyl)porphyrin manganese.

5. The metalloporphyrin / carbon nanotube composite catalyst prepared by the preparation method of any one of claims 1-4.

6. The use of the metalloporphyrin / carbon nanotube composite catalyst of claim 5 in electrocatalytic oxygen atom transfer reactions; preferably, the use in oxygen atom transfer reactions for selective oxidation of sulfides to sulfoxides under anodic conditions with water as the oxygen source.

7. A method for the selective oxidation of sulfides to sulfoxides by electrocatalytic oxygen atom transfer, characterized in that, Comprise: Providing the metalloporphyrin / carbon nanotube composite catalyst of claim 5; Using the metalloporphyrin / carbon nanotube composite catalyst as an anode catalyst, using water as an oxygen source, and catalyzing the electrocatalytic oxidation reaction of a sulfide substrate in an organic electrolyte system under a constant potential or constant current condition to prepare a sulfoxide product.

8. The method of claim 7, wherein, Specifically comprising: The metalloporphyrin / carbon nanotube composite catalyst is applied to conductive carbon paper as an anode working electrode, an organic solvent-water system is used as an electrolyte, and then an electrolyte is added to catalyze the electrocatalytic oxidation reaction of a sulfide substrate.

9. The method of claim 8, wherein: The loading amount of the metalloporphyrin / carbon nanotube composite catalyst in the anode working electrode is 0.1~2 mg / cm², preferably 1 mg / cm²; And / or, the volume ratio of the organic solvent to water in the electrolyte is (1:1)~(50:1), preferably 10:1; And / or, the organic solvent is a water-miscible organic solvent, and the organic solvent includes any one or a combination of acetonitrile, tetrahydrofuran, dioxane, and acetone; And / or, the electrolyte includes any one or a combination of tetra-n-butylammonium hexafluorophosphate, tetra-n-butylammonium tetrafluoroborate, tetra-n-butylammonium perchlorate, tetra-n-butylammonium bromide, and sodium perchlorate; And / or, the sulfide substrate comprises an aryl sulfide substrate and / or an aliphatic sulfide substrate; preferably, the sulfide substrate comprises any one or more of a combination of benzyl sulfide, p-chlorobenzyl sulfide, 4-methoxybenzyl sulfide, 2-(methylthio)pyridine, dibenzothiophene, dibutyl sulfide, omeprazole sulfide.

10. The method of claim 7, wherein: The electro-catalytic oxidation reaction is carried out at a voltage of 0.5-1.0V (vs Fc / Fc + ), a reaction temperature of 20-60℃, and a current density controlled within 50mA / cm 2 .

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