A catalyst for electrocatalytic oxidation cyclization synthesis of cyclopentathiophene or its derivatives and application thereof

Abstract

The application discloses a method for synthesizing cyclopentadithiophene or its derivative by electrocatalytic oxidation based on NiMo alloy. The method uses NiMo alloy as a working electrode catalyst to perform constant potential electrolysis in an electrolyte containing a substrate, so that dithiophene methanol or dithiophene-based methane substrate is subjected to oxidative cyclization to generate cyclopentadithiophene and its derivative. Under electrochemical conditions, Mo in the NiMo alloy catalyst is preferentially de-alloyed to form an unsaturated coordination Ni site, accelerates the conversion of Ni to active species NiOOH, and only 2 cycles of cyclic voltammetry scanning are needed to complete the reconstruction; the dissolved Mo is adsorbed on the catalyst surface in the form of MoO4 2‑ , blocks Cl ‑ in the electrolyte from approaching the active site through electrostatic repulsion, and at the same time, the residual Mo modulates the electronic structure of NiOOH and optimizes the adsorption energy of the intermediate. The method does not need to add a chemical oxidant, the residual metal in the product is less than 10 ppm, the separation yield of cyclopentadithiophene can reach 85%, the faradic efficiency can reach 83%, and the catalyst can be recycled for more than 8 times.

Description

Technical Field

[0001] This application belongs to the field of organic electrosynthesis and optoelectronic material preparation technology, specifically relating to a method for electrocatalytic oxidative cyclization synthesis of cyclopentylthiophene or its derivatives, and a method for preparing cyclopentylthiophene or its derivatives by rapidly self-reconstructing and catalyzing the oxidative cyclization reaction of bisthiophene methanol or dithiophene methane substrates under electrochemical conditions using a NiMo alloy catalyst. Background Technology

[0002] Cyclopentathiophene (CPDT) and its derivatives are important building blocks of organic optoelectronic materials. They possess a rigid, planar conjugated framework, effectively reducing the band gap of polymers and enhancing intermolecular π-π stacking. They are widely used in organic photovoltaic (OPV) cells, organic field-effect transistors (OFETs), and organic light-emitting diodes (OLEDs). With the rapid development of flexible electronics, wearable devices, and the Internet of Things (IoT), the market demand for high-quality CPDT and its derivatives continues to grow. However, current synthesis methods for CPDT materials still face numerous technical bottlenecks, hindering their large-scale production and widespread application.

[0003] Currently, the synthesis of cyclopentylthiophene mainly relies on chemical oxidative cyclization methods, with commonly used oxidants including dichlorodicyanobenzoquinone (DDQ) and ferric chloride (FeCl3). Taking the FeCl3 oxidation method as an example, its reaction mechanism is as follows: FeCl3, acting as a single-electron oxidant, oxidizes the electron-rich thiophene substrate into a free radical cation, which then undergoes intramolecular cyclization to form a C-C bond, ultimately constructing the fused-ring structure of CPDT. However, existing technologies have the following technical drawbacks: Currently, the synthesis of cyclopentylthiophene mainly relies on chemical oxidative cyclization methods using dichlorodicyanobenzoquinone (DDQ) or ferric chloride (FeCl3) as oxidants. However, existing technologies suffer from a series of insurmountable technical defects in practical applications. First, this method requires the use of stoichiometric or even excessive amounts of oxidant, resulting in the generation of large amounts of metal- or halogen-containing byproducts and waste after the reaction. This leads to poor atom economy, severe environmental pollution, and contradicts the development concept of green chemistry. Secondly, existing methods generally suffer from severe metal residue problems. In particular, even after purification steps such as column chromatography or recrystallization, the metal residue in the FeCl3 oxidation system can still reach as high as 0.5 wt% (approximately 5000 ppm). These residual metal impurities can act as carrier recombination centers or exciton quenching centers, severely reducing the performance and lifespan of optoelectronic devices such as organic solar cells, field-effect transistors, and light-emitting diodes. Thirdly, oxidants such as DDQ are highly toxic, and their reduction products are difficult to completely separate from the target product, increasing the complexity and safety risks of post-processing. Furthermore, existing chemical oxidation methods typically require stringent anhydrous and oxygen-free conditions, exhibiting limited tolerance to certain functional groups in the substrate (such as amino and alkoxy groups), thus restricting the structural diversity and further functionalization modifications of cyclopentylthiophene derivatives.

[0004] In recent years, although electrocatalytic synthesis methods have attracted attention due to their use of electrons as clean oxidants, their application in the oxidative cyclization of cyclopentathiophene still faces significant challenges: the formation kinetics of the active species NiOOH in traditional nickel-based catalysts are extremely slow, typically requiring hundreds or even thousands of cyclic voltammetric scans (lasting several hours to tens of hours) to complete reconstruction and achieve optimal catalytic activity, resulting in extremely low catalytic initiation efficiency; simultaneously, chloride ions (Cl...) in the electrolyte... - This process can severely corrode nickel-based active sites, leading to rapid catalyst deactivation. Furthermore, existing non-precious metal electrocatalysts generally suffer from a difficulty in simultaneously achieving both activity and stability, making it challenging to meet the requirements of high selectivity, high stability, and low cost for industrial production. Therefore, developing a non-precious metal electrocatalytic system capable of rapidly reconstructing the active phase, possessing effective protective capabilities, and exhibiting both high catalytic activity and long-term stability to achieve efficient, green, and high-purity electrochemical synthesis of cyclopentylthiophene and its derivatives has become a critical technical problem urgently needing to be solved in this field. Summary of the Invention

[0005] The purpose of this application is to provide a method for the electrocatalytic oxidative cyclization synthesis of cyclopentathiophene or its derivatives based on NiMo alloys, which possess rapid reconfiguration characteristics, high selectivity, high stability, high current density, and ease of preparation. This method achieves highly efficient catalysis of the oxidative cyclization reaction by constructing a NiMo alloy catalyst and utilizing its rapid self-reconfiguration characteristics under electrochemical conditions; simultaneously, it utilizes MoO4… 2- The electrostatic shielding effect protects active sites from Cl. - Erosion; Through the synergistic effect of NiMo alloy and substrate, a high-yield, high-purity, and green synthesis of cyclopentylthiophene or its derivatives was achieved, providing a new path for the industrial production of CPDT-type optoelectronic material intermediates.

[0006] To achieve the above objectives, as one aspect of this application, a method for the electrocatalytic oxidative cyclization synthesis of cyclopentylthiophene or its derivatives is provided, the method comprising:

[0007] Preparation of NiMo alloy catalysts;

[0008] Using the NiMo alloy catalyst as the working electrode catalyst, an electrolyte containing the substrate is placed in the electrolysis system, and an electrocatalytic oxidation cyclization reaction is carried out by constant potential electrolysis, so that the substrate undergoes intramolecular oxidation cyclization and is converted into cyclopentylthiophene or its derivatives.

[0009] The substrate is a dithiophene methanol compound or a dithiophene methane compound.

[0010] Optionally, in combination with any of the above aspects, in another implementation of this aspect, the synthesis of the NiMo alloy includes the following steps:

[0011] (1) NiMoO4 nanowire precursors were synthesized on a conductive substrate by a hydrothermal method;

[0012] (2) The NiMoO4 nanowire precursor is heat-treated in a reducing atmosphere to obtain the NiMo alloy.

[0013] Optionally, in combination with any of the above aspects, in another implementation of this aspect, in step (1), the reaction temperature of the hydrothermal method is 120-180°C and the reaction time is 4-12 hours; in step (2), the reducing atmosphere is a mixed atmosphere of hydrogen and argon, the heat treatment temperature is 350-500°C and the time is 3-8 hours.

[0014] Specifically, the preparation method of the NiMo alloy catalyst may include the following steps:

[0015] (1) Synthesis of NiMoO4 nanowire precursor: Nickel salt and molybdenum salt were dissolved in deionized water and stirred evenly to form a mixed solution; the pretreated conductive substrate was immersed in the mixed solution; the mixed solution was transferred into a reaction vessel with a polytetrafluoroethylene inner liner and hydrothermally reacted at 120-180°C for 4-12 hours; after the reaction was completed, the product was naturally cooled, washed and dried to obtain NiMoO4 nanowire precursor;

[0016] (2) Preparation of NiMo alloy: The NiMoO4 nanowire precursor obtained in step (1) is placed in a tube furnace and heat-treated at 350-500°C for 3-8 hours under H2 / Ar reducing atmosphere. After natural cooling, NiMo alloy catalyst is obtained.

[0017] Preferably, in step (1), the nickel salt is Ni(NO3)2·6H2O, the molybdenum salt is Na2MoO4·2H2O, and the molar ratio of Ni to Mo is 1:0.2-1, more preferably 1:0.4-0.6.

[0018] Preferably, the conductive substrate in step (1) is a nickel mesh, carbon cloth or carbon paper, more preferably a nickel mesh; the pretreatment method is to sonicate in 0.1-0.3M HCl for 20-40 minutes to remove surface oxides, and then rinse thoroughly with deionized water.

[0019] Preferably, the hydrothermal reaction temperature in step (1) is 150-170°C and the reaction time is 5-7 hours.

[0020] Preferably, the volume fraction of H2 in the H2 / Ar mixed atmosphere in step (2) is 5-15%, more preferably 10%; the heating rate is 2-10°C·min. -1 More preferably, 5°C·min -1 The heat treatment temperature is 380-420°C, and the holding time is 4-6 hours.

[0021] Optionally, in conjunction with any of the above aspects, in another implementation of this aspect, the bisthiophene methanol compound is bis(3-substituted thiophene-2-yl)methanol, wherein the substituent is selected from H, C1-C1. 12 Alkyl, C1-C 12 Any one of alkoxy groups and halogens;

[0022] The dithienylmethane compound is di(3-substituted thien-2-yl)methane, wherein the substituent is selected from H, C1-C6. 12 Alkyl, C1-C 12 Any one of alkoxy or halogen.

[0023] Alternatively, in conjunction with any of the above aspects, in another implementation of this aspect, the substrate concentration is preferably 5-20 mM, more preferably 8-12 mM.

[0024] Optionally, in conjunction with any of the above aspects, in another implementation of this aspect, the electrolyte is an organic electrolyte system or an alkaline aqueous electrolyte system. The organic electrolyte system includes a supporting electrolyte and an organic solvent. The supporting electrolyte is selected from at least one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium perchlorate, and tetraethylammonium tetrafluoroborate. The organic solvent is selected from at least one of acetonitrile, dichloromethane, and N,N-dimethylformamide. Optionally, the concentration of the supporting electrolyte in the organic system is preferably 0.05-0.2M, more preferably 0.1M.

[0025] Alternatively, the alkaline aqueous electrolyte system includes a supporting electrolyte and a solvent, wherein the supporting electrolyte is selected from at least one of KOH and NaOH, and the solvent is water. Optionally, the KOH concentration in the alkaline aqueous system is preferably 0.5-2.0M, more preferably 1.0M.

[0026] Alternatively, in conjunction with any of the above aspects, in another implementation of this aspect, when the organic electrolyte system is used, the potential of the constant potential electrolysis reaction is 0.8-1.5V vs Ag / Ag. + Alternatively, when using the alkaline aqueous electrolyte system, the potential of the constant potential electrolysis reaction is 1.3-1.6V vs RHE; the electrolysis reaction time is 1-4 hours; and the constant potential electrolysis reaction is carried out under inert gas protection.

[0027] Alternatively, in combination with any of the above aspects, in another implementation of this aspect, the NiMo alloy catalyst undergoes rapid in-situ self-reconstruction in the constant potential electrolysis reaction, and the self-reconstruction is completed within 2 cycles of cyclic voltammetry scans;

[0028] During the reconstruction process, Mo undergoes dealloying, and a highly active NiOOH phase rich in unsaturated coordinated Ni sites is formed on the surface of the NiMo catalyst.

[0029] Alternatively, in conjunction with any of the above aspects, in another implementation of this aspect, the Mo dissolved in the NiMo alloy catalyst is in the form of MoO4. 2- The form is adsorbed on the surface of the NiMo alloy catalyst, and the charge distribution on the catalyst surface is optimized through electrostatic repulsion.

[0030] Specifically, the method for electrocatalytic oxidative cyclization synthesis of cyclopentylthiophene or its derivatives may include the following steps:

[0031] (1) Dissolve the substrate and supporting electrolyte in a solvent, and purge with an inert gas (nitrogen or argon) to remove oxygen for 10-20 minutes to obtain the electrolyte;

[0032] (2) A three-electrode system is adopted, with the NiMo alloy catalyst electrode as the working electrode, the platinum sheet as the counter electrode, and the reference electrode selected according to the electrolyte system: Ag / Ag is used for organic systems. + (0.01 M AgNO3 + 0.1 M Bu4NPF6in CH3CN), alkaline aqueous system using Hg / HgO (1.0 M KOH), inserted into the electrolyte;

[0033] (3) First, perform cyclic voltammetry scanning to activate the electrode and determine the oxidation peak potential. The scan rate is 20-100 mV s. -1 Scan 2-5 times;

[0034] (4) Perform constant potential electrolysis at the oxidation peak potential for 1-4 hours, and continuously introduce inert gas for protection during the electrolysis process;

[0035] (5) After the reaction was completed, the solvent was removed by vacuum distillation and the product was purified by column chromatography to obtain the cyclopentylthiophene product.

[0036] As another aspect of this application, an electrocatalytic application of a NiMo alloy catalyst is provided, wherein the NiMo alloy catalyst is used in the electrocatalytic oxidative cyclization reaction for the synthesis of cyclopentylthiophene or its derivatives as described in any of the above aspects.

[0037] Alternatively, in combination with any of the above aspects, in another implementation of this aspect, the NiMo alloy catalyst has the dual functions of a working electrode substrate and an oxidation cyclization reaction catalyst, and can be in-situ dealloyed and reconstituted in the electrolysis reaction system to stably generate a highly active NiOOH catalytic active phase, enabling the catalytic substrate to undergo an efficient oxidation cyclization reaction.

[0038] Based on the above technical solutions, the beneficial effects of this application are as follows:

[0039] 1. Green and environmentally friendly, with no waste generation: This application uses electrons as a clean oxidant, without the need to add any stoichiometric oxidant (such as FeCl3, DDQ, etc.). The only byproduct in the reaction process is hydrogen (alkaline water system) or protons (organic system). It does not produce metal- or halogen-containing waste, has high atom economy, and meets the requirements of green chemistry and sustainable development.

[0040] 2. High product purity and extremely low metal residue: Because this method completely eliminates the use of metal oxidants, the resulting cyclopentylthiophene product has extremely low metal residue. ICP-MS analysis shows that the Ni residue in the product is less than 5 ppm, the Mo residue is less than 3 ppm, and the total metal residue is less than 10 ppm. Compared to the approximately 5000 ppm Fe residue of the traditional FeCl3 chemical oxidation method, this application reduces the metal residue by more than three orders of magnitude, completely solving the problem of metal impurities poisoning the performance of optoelectronic devices and fully meeting the stringent purity requirements of intermediates for high-end optoelectronic materials such as organic solar cells, field-effect transistors, and light-emitting diodes.

[0041] 3. Rapid Reconstruction and High Catalytic Start-up Efficiency: The NiMo alloy catalyst of this application exhibits unique rapid self-reconstruction characteristics. Under electrochemical conditions, this catalyst can complete the in-situ generation and reconstruction of the active species NiOOH in only two cyclic voltammetric scans (approximately 10 minutes), while traditional nickel-based catalysts typically require hundreds to thousands of CV cycles (several hours to tens of hours). This application shortens the reconstruction time by more than two orders of magnitude, significantly improving the catalytic start-up efficiency and enabling the electrode to be "ready to use immediately," providing convenience for continuous industrial production.

[0042] 4. High yield, good selectivity, and excellent stability: The NiMo alloy catalyst of this application achieves a separation yield of 85% for cyclopentylthiophene at a potential of 1.45 V vs RHE, with a Faradaic efficiency of 83% and an HPLC purity of 98.5%. Simultaneously, the catalyst exhibits good mechanical and chemical stability, can be recycled more than 8 times, and maintains a yield above 78% at 500 mA*cm². -2 It can operate stably for more than 1000 hours under high current density.

[0043] 5. Good substrate versatility: The method of this application is applicable to a variety of bisthiophene methanol and dithiophene methane substrates with different substituents, including H, methyl, hexyl, bromine and other substituents, with yields between 75% and 85%, providing a broad platform for the development of structural diversity of cyclopentylthiophene derivatives.

[0044] 6. Simple preparation method and promising industrialization prospects: The catalyst preparation method of this application is simple, using non-precious metals Ni and Mo as raw materials, and employing conventional hydrothermal and hydrogen reduction processes. The conditions are mild, highly controllable, and easy to scale up. Furthermore, the conductive substrate can be directly used as an electrode, eliminating the need for additional electrode coating steps. The raw material cost is low, the process is simple, and it demonstrates promising prospects for industrial application.

[0045] The above summary provides a simplified overview of some concepts, which will be further described in detail in the following specific embodiments. The above summary is not intended to identify key or essential features of the claimed subject matter, nor is it intended to help determine the scope of the claimed subject matter. The claimed subject matter is not limited to embodiments that address any or all the shortcomings pointed out in the background art.

[0046] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by means of embodiments thereof. Attached Figure Description

[0047] The accompanying drawings, incorporated in and forming part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application. To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the description of the embodiments will be briefly introduced below. Obviously, those skilled in the art can obtain other drawings based on these drawings without any creative effort. These drawings and textual descriptions are not intended to limit the scope of the concept of this application in any way, but rather to illustrate the concepts of this application to those skilled in the art by referring to specific embodiments.

[0048] Figure 1 Scanning electron microscope images of the NiMoO4 nanowire precursor in Example 1 (Figure a) and the NiMo alloy catalyst in Example 2 (Figure b) of this application;

[0049] Figure 2 This is a schematic diagram showing the comparison of cyclopentathiophene yields in Examples 3 and 4, Comparative Examples 1, 2 and 3 of this application.

[0050] Figure 3 This is a schematic diagram comparing the yields of cyclopentathiophene produced from different substrates using the NiMo alloy catalyst in Example 5 of this application.

[0051] Figure 4 This is a schematic diagram illustrating the recyclability of the NiMo alloy catalyst in Example 6 of this application;

[0052] Figure 5 This is a schematic diagram showing the performance comparison of different NiMo alloys prepared at different temperatures in Comparative Example 4 of this application;

[0053] Figure 6 This is a schematic diagram showing the performance comparison of different electrolyte systems in Comparative Example 5 of this application. Detailed Implementation

[0054] Exemplary embodiments will now be described in detail, examples of which are illustrated in the accompanying drawings. When the following description relates to the drawings, unless otherwise indicated, the same numbers in different drawings denote the same or similar elements. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0055] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Unless otherwise specified, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes that element. It should be further understood that, as used herein, the singular forms "a," "an," and "the" are intended to also include the plural forms, unless the context indicates otherwise. Furthermore, the terms "or," "and / or," "including at least one of the following," etc., as used herein, can be interpreted as inclusive, or mean any one or any combination thereof. Exceptions to this definition only arise when combinations of elements, functions, steps, or operations are inherently mutually exclusive in some manner.

[0056] It should be understood that the specific embodiments described herein are merely illustrative of this application and are not intended to limit the scope of this application. Unless otherwise specified, the materials, reagents, etc., used in the following embodiments are commercially available. Experimental methods not specifically described in the embodiments are generally performed under conventional conditions or as recommended by the manufacturer.

[0057] The technical solution of the present invention will be further described below in conjunction with its implementation.

[0058] Example 1: Preparation of NiMoO4 nanowire precursor

[0059] Weigh 0.6 g Ni(NO3)2·6H2O and 0.24 g Na2MoO4·2H2O and dissolve them in 30 mL of deionized water. Stir for 30 minutes until homogeneous. Immerse a 2 cm * 2 cm nickel mesh (pre-treated with 0.2 M HCl for 30 minutes to remove surface oxides, then thoroughly rinsed with deionized water) into the above mixed solution. Transfer the mixed solution to a 50 mL polytetrafluoroethylene-lined high-pressure reactor and place it in an oven for hydrothermal reaction at 160°C for 6 hours. After the reaction, allow it to cool naturally to room temperature. Wash the obtained product three times alternately with ethanol and deionized water, and dry it under vacuum at 60°C for 12 hours to obtain the NiMoO4 precursor.

[0060] Example 2: Preparation of NiMo alloy catalyst

[0061] The NiMoO4 precursor prepared in Example 1 was placed in a tube furnace and heated in a H2 / Ar mixed atmosphere (H2 volume fraction 10%, total flow rate 50 mL·min). -1 At 5 °C·min -1 The temperature was increased to 400 °C at a rising rate and held for 5 hours. After the holding period, the catalyst was naturally cooled to room temperature under an H2 / Ar atmosphere to obtain a NiMo alloy catalyst with a loading of approximately 3.64 mg cm⁻¹. -2 .

[0062] Example 3: Electrocatalytic oxidative cyclization synthesis of cyclopentathiophene (alkaline water electrolyte system)

[0063] In this embodiment, bis(3-bromothiophene-2-yl)methanol was used as the substrate (10 mM, dissolved in a small amount of acetonitrile before addition), and 1.0 M KOH aqueous solution (pH=14) was used as the electrolyte. A three-electrode system was employed for the electrocatalytic oxidative cyclization reaction. The working electrode was the NiMo alloy electrode (1 cm * 1 cm) prepared in Example 2, the counter electrode was a platinum sheet (2 cm * 2 cm), and the reference electrode was Hg / HgO (1.0 M KOH). The potential conversion formula was E. RHE =E Hg / HgO +0.059pH + 0.095 = E Hg / HgO +0.921V. The specific operating steps are as follows: Dissolve the substrate in a small amount of acetonitrile, then add it to 1.0 M KOH electrolyte, and purge with nitrogen gas for 15 minutes to remove oxygen; insert the three electrodes and apply 50 mV / s. -1Cyclic voltammetry was performed at a scan rate (potential range 1.0–1.7 V vs RHE), with 3 scans to complete electrode reconstruction; then, electrolysis was performed at a constant potential of 1.45 V vs RHE for 1.5 hours. After the reaction, the product was extracted with dichloromethane, the organic phase was dried over anhydrous sodium sulfate, the solvent was removed under reduced pressure, and the product was purified by column chromatography (petroleum ether / dichloromethane = 4:1) to obtain the cyclopentylthiophene product. The calculated separation yield in this example was 85%, the HPLC purity was 98.5%, and ICP-MS analysis showed that the residual Ni content in the product was less than 5 ppm and the residual Mo content was less than 3 ppm, with a Faraday efficiency of 83%.

[0064] Example 4: Electrocatalytic oxidative cyclization synthesis of cyclopentylthiophene (organic electrolyte system)

[0065] In this embodiment, bis(3-bromothiophene-2-yl)methanol was used as the substrate (10 mM), and 0.1 M Bu4NPF6 acetonitrile solution was used as the electrolyte. A three-electrode system was employed for the electrocatalytic oxidative cyclization reaction. The working electrode was the NiMo alloy electrode (1 cm * 1 cm) prepared in Example 2, the counter electrode was a platinum sheet (2 cm * 2 cm), and the reference electrode was Ag / Ag. + (0.01M AgNO3 + 0.1M Bu4NPF6 / CH3CN). The specific operating steps are as follows: Dissolve the substrate and supporting electrolyte in acetonitrile, bubble with nitrogen for 15 minutes to remove oxygen; insert a three-electrode system, and apply 50mV / s. -1 Cyclic voltammetry scans were performed at a scan rate (potential range 0~+1.2V vs Ag / Ag). + ), scan 3 times to activate the electrode and determine the oxidation peak potential; then at 1.05V vs Ag / Ag + Electrolysis was performed at a constant potential for 2 hours. After the reaction was completed, the solvent was removed under reduced pressure, and the product was purified by column chromatography (petroleum ether / dichloromethane = 4:1) to obtain the cyclopentylthiophene product. The calculated separation yield in this example was 82%, the HPLC purity was 98.2%, and the Faraday efficiency was 79%.

[0066] Example 5: Investigation of the Applicability Range of Different Substrates

[0067] This embodiment follows the method of Example 3, conducting electrocatalytic oxidative cyclization reactions with different substrates to examine the substrate universality of the method of this application. The substrates include bis(3-bromothiophene-2-yl)methanol, bis(3-methylthiophene-2-yl)methanol, dithienylmethane, and bis(3-hexylthiophene-2-yl)methanol. Experimental results show that: with bis(3-bromothiophene-2-yl)methanol as the substrate, the yield of cyclopentylthiophene is 85% after 1.5 hours of reaction; with bis(3-methylthiophene-2-yl)methanol as the substrate, the yield of 4,4-dimethyl-cyclopentylthiophene is 79% after 2.5 hours of reaction; with dithienylmethane as the substrate, the yield of cyclopentylthiophene is 75% after 3 hours of reaction; and with bis(3-hexylthiophene-2-yl)methanol as the substrate, the yield of 4,4-dihexyl-cyclopentylthiophene is 80% after 2 hours of reaction. The above results indicate that the method of this application is applicable to substrates with various substituents, including electron-donating groups (methyl, hexyl) and electron-withdrawing groups (bromine), with a stable yield between 75% and 85%, demonstrating good substrate versatility.

[0068] Example 6: Catalyst recycling performance

[0069] This example investigated the recycling performance of the NiMo alloy catalyst. The NiMo alloy electrode used in Example 3 was removed, washed three times alternately with acetonitrile and deionized water, dried under vacuum at 60°C, and the experimental steps of Example 3 were repeated for the next round of reaction, for a total of 10 cycles. The experimental results showed that the yield of cyclopentylthiophene was 85% in the first cycle; 83% in the third cycle; 81% in the fifth cycle; 78% in the eighth cycle; and 74% in the tenth cycle. These results indicate that the NiMo alloy catalyst can be stably recycled more than 8 times, maintaining a yield above 78%, exhibiting excellent mechanical and chemical stability. The retention of catalyst performance is attributed to the integrity of the NiMo alloy structure and the presence of MoO4. 2- The in-situ protection of the active sites allows the catalyst to maintain high catalytic activity even after multiple cycles.

[0070] Comparative Example 1: No catalyst control

[0071] Under the same electrolysis conditions, a blank nickel mesh was used instead of the NiMo alloy as the working electrode, and the other conditions were the same as in Example 3. After 1.5 hours of reaction, the yield of cyclopentylthiophene was only 12%, indicating that the NiMo alloy catalyst had a significant promoting effect on the reaction.

[0072] Comparative Example 2: NiMoO4 Precursor Control

[0073] NiMoO4 prepared in Example 1 was used instead of NiMo alloy as the working electrode, with other conditions the same as in Example 3. Cyclic voltammetry scans showed that the oxidation onset potential of NiMoO4 (1.30 V vs RHE) was significantly higher than that of NiMo alloy (1.25 V vs RHE), and it required more than 10 CV scans to reach stable activity, while NiMo alloy only required 2 scans. After 1.5 hours of reaction, the yield of cyclopentylthiophene was 58%, lower than the 85% yield of NiMo alloy.

[0074] Comparative Example 3: Chemical Oxidation Method (Comparison)

[0075] The conventional FeCl3 oxidative cyclization method was employed: 1 mmol of bis(3-bromothiophene-2-yl)methanol was dissolved in 10 mL of dichloromethane, and 3 mmol of FeCl3 was added. The mixture was stirred at room temperature for 12 hours. After purification by column chromatography, the product yield was 76%, the HPLC purity was 97.2%, and ICP-MS analysis showed that the residual Fe content in the product was 0.52 wt% (approximately 5200 ppm).

[0076] Comparative Example 4: Performance Comparison of NiMo Alloys Prepared at Different Temperatures

[0077] Following the method of Example 2, NiMo alloy catalysts were prepared at different heat treatment temperatures (350°C, 400°C, 450°C, and 500°C), and their catalytic performance was tested according to the method of Example 3. The results showed that the NiMo alloy catalyst prepared at 400°C had the best performance (yield of 85%). At too low a temperature (350°C), the reduction was incomplete, and at too high a temperature (500°C), the alloy particles agglomerated, resulting in a decrease in performance.

[0078] Comparative Example 5: Performance Comparison of Different Electrolyte Systems

[0079] This comparative study investigated the effects of different electrolyte systems on the electrocatalytic oxidative cyclization reaction of NiMo alloys to synthesize cyclopentylthiophene. Following the method in Example 3, three electrolytes were used for the electrocatalytic oxidative cyclization reaction: 1.0 M KOH aqueous solution, 0.1 M KHCO3 aqueous solution, and 0.1 MBu4NPF6 / acetonitrile organic system. The substrate was bis(3-bromothiophene-2-yl)methanol (10 mM). The reaction potentials were 1.45 V vs RHE (1.0 M KOH and 0.1 M KHCO3 systems) and 1.05 V vs Ag / Ag, respectively. +(0.1 M Bu4NPF6 / acetonitrile system), reaction time was 1.5 hours. Experimental results showed that the highest separation yield of cyclopentylthiophene (85%) and Faraday efficiency (83%) were achieved when using 1.0 M KOH as the electrolyte. This is because strongly alkaline conditions favor the rapid reconstruction of NiMo alloys and the in-situ formation of the NiOOH active phase, while OH... - The high concentration of HCO3 promoted the deprotonation step of the substrate. When using 0.1 M KHCO3 as the electrolyte, the separation yield of cyclopentylthiophene was 72%, and the Faradaic efficiency was 70%, which was lower than that of the 1.0 M KOH system. This was mainly because the KHCO3 system was less alkaline (pH approximately 8.3), which was not conducive to the rapid formation of the NiOOH active phase. Additionally, CO2 had low solubility under near-neutral conditions. Although this comparative example did not involve CO2 reduction, the KHCO3:HCO3 content in the system... - : with CO3 2- The buffering effect of the acetonitrile affects the local pH environment on the electrode surface, thus influencing the reaction kinetics. When using a 0.1M Bu4NPF6 / acetonitrile organic system as the electrolyte, the separation yield of cyclopentylthiophene is 82%, and the Faradaic efficiency is 79%, similar to the 1.0M KOH system. Product separation is also simpler (no extraction is required; solvent can be removed directly by evaporation). However, the organic system has poor conductivity, requiring the addition of a higher concentration of supporting electrolyte. Furthermore, acetonitrile has a certain degree of toxicity, necessitating consideration of solvent recovery and safety measures for industrial applications. In summary, the 1.0M KOH aqueous system exhibits the best performance in terms of yield and Faradaic efficiency, and also offers advantages in environmental friendliness and low cost, making it the preferred electrolyte system for this application. The 0.1M Bu4NPF6 / acetonitrile organic system can serve as an alternative, particularly suitable for the electrocatalytic oxidation cyclization reaction of water-sensitive substrates.

[0080] The sequence numbers of the embodiments in this application are for descriptive purposes only and do not represent the superiority or inferiority of the embodiments.

[0081] In this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions are generally described in detail only when they appear for the first time. When they appear again, they are generally not repeated for the sake of brevity. When understanding the technical solutions and other contents of this application, the same or similar terms, concepts, technical solutions and / or application scenario descriptions that are not described in detail later can be referred to their previous relevant detailed descriptions.

[0082] In this application, the descriptions of the various embodiments have different focuses. For parts that are not described in detail or recorded in a certain embodiment, please refer to the relevant descriptions of other embodiments.

[0083] The technical features of the present application can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of the present application.

[0084] The above are merely preferred embodiments of this application and do not limit the patent scope of this application. Any equivalent structural or procedural transformations made using the content of this application's specification and drawings, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of this application.

Claims

1. A method for the electrocatalytic oxidative cyclization synthesis of cyclopentylthiophene or its derivatives, characterized in that, The method includes: Preparation of NiMo alloy catalysts; Using the NiMo alloy catalyst as the working electrode catalyst, an electrolyte containing the substrate is placed in the electrolysis system, and an electrocatalytic oxidation cyclization reaction is carried out by constant potential electrolysis, so that the substrate undergoes intramolecular oxidation cyclization and is converted into cyclopentylthiophene or its derivatives. The substrate is a dithiophene methanol compound or a dithiophene methane compound.

2. The method according to claim 1, characterized in that, The synthesis of the NiMo alloy includes the following steps: (1) NiMoO4 nanowire precursors were synthesized on a conductive substrate by a hydrothermal method; (2) The NiMoO4 nanowire precursor is heat-treated in a reducing atmosphere to obtain the NiMo alloy.

3. The method according to claim 2, characterized in that, In step (1), the reaction temperature of the hydrothermal method is 120-180°C and the reaction time is 4-12 hours; in step (2), the reducing atmosphere is a mixed atmosphere of hydrogen and argon, the heat treatment temperature is 350-500°C and the time is 3-8 hours.

4. The method according to claim 1, characterized in that, The bisthiophene methanol compound is bis(3-substituted thiophene-2-yl)methanol, wherein the substituent is selected from H, C1-C. 12 Alkyl, C1-C 12 Any one of alkoxy groups and halogens; The dithienylmethane compound is di(3-substituted thien-2-yl)methane, wherein the substituent is selected from H, C1-C6. 12 Alkyl, C1-C 12 Any one of alkoxy or halogen.

5. The method according to claim 1, characterized in that, The electrolyte is an organic electrolyte system or an alkaline aqueous electrolyte system. The organic electrolyte system includes a supporting electrolyte and an organic solvent. The supporting electrolyte is selected from at least one of tetrabutylammonium hexafluorophosphate, tetrabutylammonium perchlorate, and tetraethylammonium tetrafluoroborate. The organic solvent is selected from at least one of acetonitrile, dichloromethane, and N,N-dimethylformamide. Alternatively, the alkaline aqueous electrolyte system includes a supporting electrolyte and a solvent, wherein the supporting electrolyte is selected from at least one of KOH and NaOH, and the solvent is water.

6. The method according to claim 5, characterized in that, When using the aforementioned organic electrolyte system, the potential of the constant-potential electrolysis reaction is 0.8-1.5V vs Ag / Ag. + Alternatively, when using the alkaline aqueous electrolyte system, the potential of the constant potential electrolysis reaction is 1.3-1.6V vs RHE; the electrolysis reaction time is 1-4 hours; and the constant potential electrolysis reaction is carried out under inert gas protection.

7. The method according to claim 1, characterized in that, The NiMo alloy catalyst undergoes rapid in-situ self-reconstruction in the constant potential electrolysis reaction, and the self-reconstruction is completed within 2 cycles of cyclic voltammetry scans. During the reconstruction process, Mo undergoes dealloying, and a highly active NiOOH phase rich in unsaturated coordinated Ni sites is formed on the surface of the NiMo catalyst.

8. The method according to claim 7, characterized in that, The Mo dissolved in the NiMo alloy catalyst is in the form of MoO4. 2- The form is adsorbed on the surface of the NiMo alloy catalyst, and the charge distribution on the catalyst surface is optimized through electrostatic repulsion.

9. An electrocatalytic application of a NiMo alloy catalyst, characterized in that, The NiMo alloy catalyst is used in the electrocatalytic oxidative cyclization reaction for the synthesis of cyclopentylthiophene or its derivatives as described in any one of claims 1-8.

10. The application according to claim 9, characterized in that, The NiMo alloy catalyst has the dual functions of working electrode matrix and oxidation cyclization reaction catalyst. It can be in-situ dealloyed and reconstituted in the electrolysis reaction system to stably generate a highly active NiOOH catalytic phase, and the catalytic substrate undergoes an efficient oxidation cyclization reaction.

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