A method for the oxidative synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives

Abstract

This application provides a method for the oxidative synthesis of dihydronaphthyl-1(2H)-one from styrene and its derivatives, comprising: electrochemically catalytically oxidizing styrene and its derivatives to 3,4-dihydronaphthyl-1(2H)-one in an electrochemical catalytic reactor; wherein the working electrode of the electrochemical catalytic reactor is a platinum nanoparticle electrode. This reaction does not require stringent temperature and pressure conditions, does not use additional oxidizing or reducing agents, and utilizes only the cleanest reaction reagent, "electrons," to generate the required catalyst or reactive intermediate in situ. The electrode materials are inexpensive and readily available, the process is simple, and highly reproducible. It is an efficient, safe, and environmentally friendly production process with potential industrial application value.

Description

Technical Field

[0001] This invention belongs to the field of organic synthesis technology, and particularly relates to a method for the oxidative synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives. Background Technology

[0002] Styrene and its derivatives possess unique structural characteristics. In styrene, the electrons of the vinyl group are conjugated with the benzene ring, making it insoluble in water but soluble in most organic solvents such as ethanol and diethyl ether. Styrene and its derivatives have wide applications in organic chemical production, serving as important monomers for synthesizing resins, ion exchange resins, and synthetic rubber, and are also used in the pharmaceutical, dye, pesticide, and mineral processing industries.

[0003] Industrially, styrene and its derivatives, when oxidized, can produce a variety of industrial products such as benzyl alcohol, benzaldehyde, benzoic acid, phenyl ethylene oxide, and 1-phenylethane-1,2-diol, which have high added value. In particular, the oxidative coupling of styrene can produce many biomolecular structures and is an effective means of extending carbon chains in molecules. Traditional oxidative coupling methods often require heavy metals or strong oxidants, resulting in high material and energy consumption, severe environmental pollution, and difficult post-processing of the products, thus greatly limiting their application. Therefore, environmentally friendly, efficient, and green economic methods for styrene oxidative coupling are receiving increasing attention and importance.

[0004] In recent decades, the shape-controlled synthesis of platinum (Pt)-based noble metal nanocrystals has been extensively studied in the field of electrocatalysis. Researchers have synthesized various platinum-based noble metal nanocrystals (PtNCs) with different morphologies, compositions, and sizes using different methods, and applied them to important electrocatalytic reactions such as oxygen reduction reaction, hydrogen evolution reaction (HER), and ethanol oxidation reaction (EOR). Among them, platinum nanoparticles (PtNPs) have a wide range of applications due to their unique chemical and physical properties. As a noble metal, platinum has excellent electrical conductivity. Simultaneously, it is chemically stable, possesses good mechanical properties and corrosion resistance, and exhibits high electrocatalytic activity for the iodine / triiodine redox reaction, often used as the counter electrode (CE) of DSSCs. Its optical properties can be used in electronic, catalytic, sensing, and photovoltaic applications.

[0005] Carbon materials are particularly valuable due to their excellent properties, such as tunable shape, size and porosity, chemical stability, corrosion resistance, low cost, good heat resistance and electrical conductivity. The combination of all these properties promotes the use of these materials as electrode carriers.

[0006] Due to the high catalytic performance of these materials and the diverse applications of the products from styrene oxidation, the preparation methods of new materials for styrene oxidation are receiving increasing attention, particularly the use of highly efficient catalysts or green oxidation methods, which have become a research hotspot both domestically and internationally. Currently reported methods for styrene oxidation include the following:

[0007] A 2022 report describes the oxidation of styrene to benzaldehyde. Using styrene as a raw material, sodium periodate and ruthenium are used as co-oxidants to catalytically oxidize styrene, removing a carbon atom to produce benzaldehyde. This type of reaction uses inexpensive and readily available raw materials and has a high product yield. (Applied Organometallic Chemistry. 2022, 36(10), e6831). Furthermore, a photo-promoted bimetallic catalytic oxidation method for styrene to benzaldehyde was reported in 2024. This method uses Cu-BTC-TiO2 nanoparticles as catalysis, greatly improving catalytic efficiency, but the complex MOF fabrication process limits its industrial application. (Appl Organomet Chem. 2024; 38e7594.)

[0008]

[0009] In addition, there are reports of styrene oxidative coupling. These reactions typically use styrene or its derivatives as reactants. Under the presence of an external oxygen source, one molecule of styrene is oxidized to produce an active intermediate, which then attacks another molecule of styrene, thus completing the oxidative coupling process. These reactions usually synthesize a large molecule from two molecules of styrene, and are of great value both in theoretical research and practical applications. For example, under photocatalytic oxygen participation, acetonitrile can be used as a solvent to oxidatively couple styrene to dihydronaphthalene-1(2H)-one or its derivatives. They use light as a direct energy source, enabling efficient and green styrene oxidation, but the expensive acridine-based photocatalysts greatly limit their application.

[0010] Another report describes the use of TiO2 photocatalysts. This method involves passing oxygen through a photocatalyst, causing it to lose an electron and become a more reactive oxygen radical, which then initiates a styrene reaction and dimerizes, ultimately producing a dihydronaphthalene-1(2H)-one product. (Green Chem., 2016, 18, 2864-2870)(Advanced Synthesis & Catalysis, 2016, 358(23): 3887-3896.)(ACS Catal. 2016, 6, 8389-8394)

[0011]

[0012] While these reactions can simply and efficiently oxidize styrene or its derivatives and have a wide range of applicable substrates, they also have several drawbacks: the use of transition metal or noble metal catalysts leads to the loss of precious metals and environmental pollution to some extent; the use of strong oxidizing and reducing agents increases the risk of the reaction to some extent, which does not meet the requirements of environmentally friendly green synthesis methods; and the use of photocatalysts makes post-reaction processing difficult, and some reactions require specific equipment and instruments, which limits the application of this reaction. Summary of the Invention

[0013] The present invention aims to provide a method for the oxidative synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives without the need for transition metal or noble metal catalysts, strong oxidants, or photocatalysis.

[0014] To achieve the above objectives, the present invention provides a method for the oxidative synthesis of dihydronaphthyl-1(2H)-one from styrene and its derivatives, comprising: electrochemically catalytically oxidizing styrene and its derivatives to 3,4-dihydronaphthyl-1(2H)-one in an electrochemical catalytic reactor, as shown in the following reaction formula:

[0015]

[0016] Wherein: R1 is independently selected from one of hydrogen, halogen, substituted or unsubstituted C1-10 alkyl, substituted or unsubstituted aryl, substituted or unsubstituted C1-10 alkoxy, substituted or unsubstituted amino, carboxyl, ester, acyl, cyano, nitro, hydroxy, and azide.

[0017] Furthermore, the electrolyte is one or more of lithium perchlorate, ammonium perchlorate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetraethylbenzenesulfonate, and tetraethylammonium acetate.

[0018] Furthermore, in the method for preparing the aromatic aldehydes and their derivatives, the oxygen content in the oxygen atmosphere is greater than 0%.

[0019] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives, wherein the solvent is one or more selected from water, methanol, ethanol, acetonitrile, benzene, toluene, tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, hexafluoroisopropanol, trifluoroacetic acid, ethylene glycol, and polyethylene glycol.

[0020] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives, characterized in that the counter electrode of the electrochemical catalytic reactor is one or more of the following: platinum electrode, nickel electrode, graphite electrode, glassy carbon electrode, copper electrode, magnesium electrode, silver electrode, iron electrode, and gold electrode.

[0021] Furthermore, in the platinum electrode catalysis for the synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives, the electrochemical catalytic reactor's electrolytic cell is one of a dual-cell structure separated by a diaphragm, a single-cell structure without a diaphragm, or a continuous flow electrochemical reaction cell.

[0022] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthyl-1(2H)-one from styrene and its derivatives. The electrochemical catalytic reaction is carried out by either constant current or constant voltage, with the constant voltage range being 0–30V and the constant current range being 0–100mA.

[0023] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives, with the reaction temperature ranging from 0 to 50°C and the reaction time from 0 to 36 h.

[0024] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthalene-1(2H)-one from styrene and its derivatives, wherein the concentration of styrene or its derivatives in the solvent is 0.001 mol / L to 0.5 mol / L.

[0025] Furthermore, the platinum electrode catalyzes the synthesis of dihydronaphthyl-1(2H)-one from styrene and its derivatives. The reaction solution containing dihydronaphthyl-1(2H)-one obtained from the electrochemical catalytic reaction is concentrated, purified by silica gel column chromatography, and freeze-dried to obtain dihydronaphthyl-1(2H)-one.

[0026] Further, the organic phase was washed multiple times with water and dried with anhydrous magnesium sulfate, and finally the organic phase was concentrated to obtain dihydronaphthyl-1(2H)-one.

[0027] Furthermore, the concentration is achieved using one of the following methods: atmospheric distillation, vacuum distillation, or rotary evaporation.

[0028] Furthermore, post-processing can also be performed using column chromatography purification, wherein the column chromatography uses 200-300 mesh silica gel as the separation resin, and the eluent is selected from at least one of petroleum ether, n-hexane, dichloromethane, water, acetonitrile, methanol, and ethyl acetate.

[0029] The above-mentioned platinum nanoparticle electrode is prepared by isopotential electrodeposition on a substrate in a platinum ion-containing deposition solution to obtain a platinum nanoparticle electrode.

[0030] Furthermore, in the preparation of the platinum nanoparticle electrode, the substrate material is one or more of carbon paper, carbon felt, glassy carbon, mesh glassy carbon, nickel foam, and copper foam.

[0031] Furthermore, in the preparation of the platinum nanoparticle electrode, the source of metallic platinum in the deposition solution can be one of platinum dichloride, chloroplatinic acid, potassium chloroplatinate, or dinitrosodiamineplatinum, and the concentration of platinum ions can be 0.01-100 mmol / L.

[0032] Furthermore, in the preparation of the platinum nanoparticle electrode, the anions in the deposition solution are each independently selected from one or more of fluoride ions, chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, perchlorate ions, and p-toluenesulfonate ions, wherein the concentration of the anions is 0.005-0.5 mol / L.

[0033] Furthermore, the preparation of the platinum nanoparticle electrode is characterized by the use of underpotential deposition, isopotential deposition, or overpotential deposition as the electrodeposition method, with a deposition potential of -0.5V to -1.2V. The deposition time is between 10 and 300 seconds.

[0034] The structural formula of the above dihydronaphthalene-1(2H)-one is shown below:

[0035]

[0036] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0037] This invention loads platinum nanoparticles onto conductive carbon paper, replacing the expensive platinum electrode with a low-cost carbon-based material, thus saving reaction costs and significantly improving catalytic activity. Simultaneously, this electrode is used for the catalytic oxidation of styrene and its derivatives to obtain a series of higher value-added products such as 3,4-dihydronaphthyl-1(2H)-one. This reaction does not require stringent temperature and pressure conditions, nor does it use additional redox agents; it utilizes only the cleanest reaction reagent, "electrons," to generate the desired catalyst or reactive intermediates in situ. The electrode material is inexpensive and readily available, the process is simple, and highly reproducible. It is an efficient, safe, and environmentally friendly production process with potential industrial application value. Attached Figure Description

[0038] Figure 1 The deposition curve of the platinum nanoparticle electrode is shown.

[0039] Figure 2 The image shows the XRD characterization of platinum nanoparticles.

[0040] Figure 3 SEM characterization image of platinum nanoparticles;

[0041] Figure 4 The image shows the SEM energy spectrum of platinum nanoparticles.

[0042] Figure 5 For example, compound 3a1 1H NMR carbon NMR spectrum;

[0043] Figure 6 For example, compound 3a 13 C10 NMR spectrum.

[0044] Figure 7 For example, compound 3b 1 1H NMR carbon NMR spectrum;

[0045] Figure 8 For example, compound 3b 13 C10 NMR spectrum.

[0046] Figure 9 For example, compound 3c 1 1H NMR carbon NMR spectrum;

[0047] Figure 10 For example, compound 3c 13 C10 NMR spectrum.

[0048] Figure 11 For example, compound 3d 1 1H NMR carbon NMR spectrum;

[0049] Figure 12 For example, compound 3d 13 C10 NMR spectrum. Detailed Implementation

[0050] The embodiments of the technical solution of this application will now be described in detail with reference to the accompanying drawings. These embodiments are only used to more clearly illustrate the technical solution of this application and are therefore merely examples, and should not be used to limit the scope of protection of this application.

[0051] This invention provides a method for synthesizing styrene and its derivatives into 3,4-dihydronaphthyl-1(2H)-one. In an electrochemical catalytic reactor, styrene and its derivatives are electrochemically catalytically oxidized to 3,4-dihydronaphthyl-1(2H)-one; the reaction formula is as follows:

[0052]

[0053] Each of the R groups is independently selected from one of hydrogen, halogen, substituted or unsubstituted C1-10 alkyl, substituted or unsubstituted aryl, substituted or unsubstituted C1-10 alkoxy, substituted or unsubstituted amino, carboxyl, ester, acyl, cyano, nitro, hydroxyl, and azide.

[0054] The working electrode of the electrochemical catalytic reactor used in this invention is a platinum nanoparticle electrode.

[0055] According to this invention, the electrochemically catalyzed electrolyte is one or more of lithium perchlorate, ammonium perchlorate, tetrabutylammonium tetrafluoroborate, tetrabutylammonium hexafluorophosphate, tetraethylbenzenesulfonate, and tetraethylammonium acetate. It should be understood that in the reaction of this invention, the common feature of the above electrolytes is that they are either ammonium salts or lithium salts. In the reaction of this invention, all of the above electrolytes can create the electrochemically catalyzed electrolysis conditions. Therefore, as long as any of the above electrolytes is selected, the above-mentioned reaction of this application can be achieved. Although only some examples of electrolytes are given in the specific embodiments of this invention, those skilled in the art should understand that the examples are merely used to explain the preferred embodiments given by this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention by using other electrolytes given in this invention, based on the guidance of the examples.

[0056] According to the present invention, the oxygen content in the oxygen atmosphere is greater than 0%. It should be understood that in the reaction of the present invention, the above reaction can occur as long as styrene or its derivatives, oxygen, and electrochemically catalyzed reaction conditions are present. Although only some parameters regarding oxygen content are given in the specific embodiments of the present invention, those skilled in the art should understand that the embodiments are merely used to explain the preferred implementation schemes given by the present invention and are not intended to limit the present invention. Those skilled in the art can also obtain the present invention according to other parameters given in the present invention based on the guidance provided in the embodiments.

[0057] According to this invention, the solvent is one or more selected from water, methanol, ethanol, acetonitrile, benzene, toluene, tetrahydrofuran, 1,4-dioxane, dimethyl sulfoxide, N,N-dimethylformamide, hexafluoroisopropanol, trifluoroacetic acid, ethylene glycol, and polyethylene glycol. It should be understood that in the reaction of this invention, the above-mentioned solvents are only used to dissolve the reactants; the solvents themselves do not participate in the reaction. Therefore, any solvent capable of dissolving the reactants can achieve the above-mentioned reaction. Although only some of the above-mentioned solvents are given as reaction solvents in the specific embodiments of this invention, those skilled in the art should understand that the embodiments are merely used to explain the preferred embodiments given by this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention using other solvents given in this invention, based on the guidance of the embodiments.

[0058] According to this invention, the counter electrode of the electrochemical catalytic reactor is one or more of the following: platinum electrode, nickel electrode, graphite electrode, glassy carbon electrode, copper electrode, magnesium electrode, silver electrode, iron electrode, and gold electrode. The electrolytic cell of the electrochemical catalytic reactor is one of a dual-cell structure separated by a diaphragm, a single-cell structure without a diaphragm, or a continuous flow electrochemical reaction cell. The electrolysis method of the electrochemical catalytic reaction is one of constant current or constant voltage, with a constant voltage range of 0–30V and a constant current range of 0–100mA. It should be understood that in the reaction of this invention, the counter electrode provides the conductive environment of the electrolytic cell; the counter electrode itself does not participate in the reaction. The type of electrolytic cell is a unique device for electrolytic reactions. Therefore, as long as a suitable counter electrode and electrolytic cell are selected, the above-mentioned reaction can be achieved. Although only preferred embodiments of the reaction in the above-mentioned devices are given in the specific embodiments of this invention, those skilled in the art should understand that the embodiments are only used to explain the preferred implementation schemes given by this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention by using other solvents given in this invention under the guidance of the embodiments.

[0059] According to the present invention, the reaction solution containing dihydronaphthyl-1(2H)-one obtained by using the prepared platinum nanoelectrode for the catalytic reaction of styrene is concentrated, purified by silica gel column chromatography, and freeze-dried to obtain dihydronaphthyl-1(2H)-one.

[0060] Furthermore, the platinum nanoparticle electrode of the present invention is prepared by means of isopotential electrodeposition on a substrate in a platinum ion-containing deposition solution to obtain a platinum nanoparticle electrode.

[0061] According to this invention, the substrate material is one or more selected from carbon paper, carbon felt, glassy carbon, reticulated glassy carbon, nickel foam, and copper foam. It should be understood that in the reaction of this invention, the common feature of the above-mentioned substrates is that they are conductive materials, and in the reaction of this invention, all of the above-mentioned substrate materials can create the preparation conditions for platinum nanoparticles. Therefore, as long as the above-mentioned substrate materials are selected, the above-mentioned reaction of this application can be achieved. Although only some examples of substrate materials are given in the specific embodiments of this invention, those skilled in the art should understand that the examples are only used to explain the preferred embodiments given by this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention by following other electrolytes given in this invention, based on the teachings of the examples.

[0062] According to this invention, the source of platinum in the deposition solution can be platinum dichloride, chloroplatinic acid, potassium chloroplatinate, or dinitrosodiamineplatinum, and the concentration of platinum ions can be 0.01-100 mmol / L. The anions in the deposition solution are each independently selected from one or more of fluoride ions, chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, perchlorate ions, and p-toluenesulfonate ions, and the concentration of the anions is 0.005-0.5 mol / L. It should be understood that in the reaction of this invention, the above-mentioned platinum ions are all platinum-containing salts and have good solubility in aqueous solution. The above-mentioned anions can all provide a good conductive environment for the solution and have an effect on the shape of platinum ions during the deposition process. Therefore, as long as the above-mentioned platinum salts and anions are selected, the above-mentioned reaction of this application can be achieved. Although only some examples of platinum salts and anions are given in the specific embodiments of this invention, those skilled in the art should understand that the examples are only used to explain the preferred embodiments given by this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention by following other platinum salts and anions given in this invention under the guidance of the examples.

[0063] According to this invention, the electrodeposition method can be selected from underpotential deposition, equal-potential deposition, or overpotential deposition, with a deposition potential of -0.5V to -1.2V. The deposition time is between 10 and 300 seconds. It should be understood that in the reaction of this invention, platinum ions can undergo deposition reaction as long as the potential for platinum ion deposition is met. Although only some deposition potential and deposition time parameters are given in the specific embodiments of this invention, those skilled in the art should understand that the embodiments are only used to explain the preferred embodiments of this invention and are not intended to limit this invention. Those skilled in the art can also obtain this invention according to other parameters given in this invention based on the teachings given in the embodiments.

[0064] The technical solution and effects of the present invention will be further illustrated below through specific embodiments.

[0065] Example of platinum nanoparticle electrode fabrication:

[0066] Preparation of substrate (carbon paper)

[0067] Cut the carbon paper into 15mm x 10mm rectangles and smooth the edges. Clean it in a 50W ultrasonic cleaner with 3M hydrochloric acid, anhydrous ethanol, acetone, and deionized water for 15 minutes each, then dry it in an 80°C oven for 2 hours.

[0068] Preparation of deposition solution

[0069] Weigh out platinum salt K2PtCl6 (240 mg) and electrolyte sodium chloride (290 mg), dissolve them in 50 ml of deionized water, and vibrate in a 50 W ultrasonic cleaner for 30 minutes to ensure that all solids are completely dissolved.

[0070] Determining the reduction potential of Pt nanoparticles

[0071] Take 10 ml of the prepared solution, clamp the working electrode (carbon paper), counter electrode (platinum sheet), and reference electrode (Ag / AgCl) onto the electrode holder, set the cyclic voltammetry parameters: initial potential 0 V, upper limit potential 0.1 V, lower limit potential -1.2 V, scan rate 50 mV / s, sensitivity 1.0e-004, and find the Pt reduction potential in the cyclic voltammogram.

[0072] Electrodeposited platinum nanoparticles

[0073] Electrodeposition was performed using the it amperometric method at the reduction potential of Pt, with the initial potential being the reduction potential of platinum. The process lasted 40 seconds, during which three electrode sheets were deposited in parallel at one time.

[0074] Figure 1 Deposition curve of platinum nanoparticle electrode in the example of platinum nanoparticle electrode preparation;

[0075] Figure 2 XRD characterization of platinum nanoparticles in the example of platinum nanoparticle electrode preparation;

[0076] Figure 3 SEM characterization image of platinum nanoparticles in the example of platinum nanoparticle electrode preparation;

[0077] Figure 4 SEM energy spectrum of platinum nanoparticles in the example of platinum nanoparticle electrode preparation;

[0078] An electrochemical catalytic reactor using the platinum nanoparticle electrode prepared in the above example was used to process styrene and its derivatives. Example of biosynthesis of dihydronaphthalene-1(2H)-one:

[0079] Example 1

[0080] The electrochemical catalytic synthesis of dihydronaphthalene-1(2H)-one 3a from styrene derivative 1a is described below, along with its structure and preparation method:

[0081]

[0082] 0.2 mmol of 4-phenylstyrene, 0.4 mmol of tetrabutylammonium hexafluorophosphate, 5 mL of acetonitrile, and 0.5 mL of water were added to a 10 mL reactor. A magnetic stir bar was added, and a platinum electrode was prepared as the anode and a platinum sheet electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate in a volume ratio of 95:5 to obtain 4-([1,1'-biphenyl]-4-yl)-7-phenyl-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 93%.

[0083] Structural identification of compound 3a:

[0084] Nuclear magnetic resonance data:

[0085] 1 H NMR(500MHz,Chloroform-d)δ8.21(d,J=8.2Hz,1H),7.59(dddd,J=13.6,12.4,7.3 ,1.9Hz,5H),7.53–7.49(m,2H),7.45–7.38(m,4H),7.36–7.32(m,2H),7.28(d,J=1. 9Hz,1H),7.24–7.21(m,2H),4.43(dd,J=7.6,4.6Hz,1H),2.81–2.75(m,1H),2.67(d dd,J=17.2,8.7,4.4Hz,1H),2.56(ddt,J=13.2,8.9,4.5Hz,1H),2.41–2.34(m,1H). 13 C NMR(126MHz,Chloroform-d)δ197.84,146.54,146.31,142.64,140.66,131.75,129.04,128.87, 128.81,128.24,128.12,127.87,127.41,127.32,127.29,127.03,126.02,45.11,36.52,31.91.

[0086] High-resolution mass spectrometry data

[0087] HRMS(ESI)m / z:[M+H]+calcd for C 14 H 14 O:374.1671 found:375.1737

[0088] Compound 3a 1 H NMR, 13 C NMR such as Figure 5 ,like Figure 6 As shown in the figure, the analysis results indicate that the target product obtained is correct.

[0089] Example 2

[0090] The electrochemical catalytic oxidation of styrene derivative 1b to synthesize dihydronaphthalene-1(2H)-one and its derivative 3b, the structure of which and the preparation method are as follows:

[0091]

[0092] 4-Methylstyrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and the prepared graphite electrode was used as the anode and a platinum sheet electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) at a ratio of 95:5 to obtain 7-methyl-4-(p-tolyl)-3,4-dihydronaphthyl-1(2H)-one, a colorless viscous liquid with a separation yield of 90%.

[0093] Structural identification of compound 3b:

[0094] Nuclear magnetic resonance data:

[0095] 1 H NMR(500MHz,Chloroform-d)δ8.06(d,J=8.0Hz,1H),7.18(t,J=8.8Hz,3H),7.04(d,J=7.9Hz,2H),6.85(s,1H),4.27(dd,J=7.7,4.6Hz,1H),2.73(ddd, J=17.1,8.6,4.3Hz,1H),2.61(ddd,J=17.1,8.7,4.4Hz,1H),2.47(ddd,J=1 3.6,8.9,4.6Hz,1H),2.39(s,3H),2.32(s,3H),2.27(td,J=8.2,4.1Hz,1H). 13C NMR(126MHz,Chloroform-d)δ198.00,146.48,144.50,140.76,136.33,130.64 ,129.96,129.35,128.52,128.08,127.24,44.86,36.51,31.98,21.80,21.07.

[0096] High-resolution mass spectrometry data

[0097] HRMS(ESI)m / z:[M+H]+calcd for C 14 H 14 O:250.1358 found:251.1362

[0098] Compound 3b 1 H NMR, 13 C NMR such as Figure 7 ,like Figure 8 As shown in the figure, the analysis results indicate that the target product obtained is correct.

[0099] Example 3

[0100] The electrochemical catalytic oxidation of styrene derivative 1c to synthesize dihydronaphthalene-1(2H)-one and its derivative 3c, the structure and preparation method of which are as follows:

[0101]

[0102] 4-Methoxystyrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and the prepared graphite electrode was used as the anode and a platinum sheet electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) at a ratio of 95:5 to obtain 7-methoxy-4-(p-methoxyphenyl)-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 91%.

[0103] Structural identification of compound 3c:

[0104] Nuclear magnetic resonance data:

[0105] 1H NMR(500MHz,Chloroform-d)δ8.11(d,J=8.7Hz,1H),7.10–7.00(m,2H),6.88(dd ,J=8.9,2.4Hz,3H),6.46(d,J=2.5Hz,1H),4.22(dd,J=8.1,4.4Hz,1H),3.82(s, 3H), 3.76 (s, 3H), 2.69 (ddd, J=17.2, 8.1, 4.4Hz, 1H), 2.58 (ddd, J=17.2, 9.0, 4. 5Hz,1H),2.43(ddt,J=12.7,8.5,4.4Hz,1H),2.26(dtd,J=13.2,8.6,4.4Hz,1H). 13 C NMR(126MHz,Chloroform-d)δ197.04,163.74,158.42,149.17,135.52,129.63 ,129.53,126.54,114.04,113.69,113.24,55.37,55.28,44.85,36.47,31.99.

[0106] High-resolution mass spectrometry data

[0107] HRMS(ESI)m / z:[M+H]+calcd for C 14 H 14 O:278.1671 found:279.1687

[0108] Compound 3c 1 H NMR, 13 C NMR such as Figure 9 ,like Figure 10 As shown in the figure, the analysis results indicate that the target product obtained is correct.

[0109] Example 4

[0110] The electrochemical catalytic oxidation of styrene derivatives 1d to synthesize dihydronaphthalene-1(2H)-one, and its derivative 3d, have the following structure and preparation method:

[0111]

[0112] 2-Methylstyrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and a prepared graphite electrode was used as the anode and a platinum sheet electrode as the cathode. The system was sealed and purged with oxygen three times. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) = 95:5 to obtain 8-methyl-4-(o-tolyl)-3,4-dihydronaphthyl-1(2H)-one, a colorless viscous liquid with a separation yield of 83%.

[0113] Structural identification of compound 3w:

[0114] Nuclear magnetic resonance data:

[0115] 1H NMR(500MHz,Chloroform-d)δ7.29–7.25(m,2H),7.19–7.12(m,3H),6.84(d,J=7.6Hz,1H),6.79(d,J=7.7Hz,1H),4.54(dd,J=8.0,4. 8Hz,1H),2.82–2.75(m,1H),2.74(s,3H),2.66(ddd,J=16.7,9.2,4.7Hz,1H),2.45(s,3H),2.39–2.36(m,1H),2.29–2.22(m,1H).13C NMR(126MHz,Chloroform-d)δ200.28,147.78,142.20,141.19,135.96,132.46,131.82 ,130.79,130.69,128.69,127.44,126.60,126.26,42.45,38.68,29.43,23.45,19.65.

[0116] High-resolution mass spectrometry data

[0117] HRMS(ESI)m / z:[M+H]+calcd for C 14 H 14 O:278.1671 found:279.1687

[0118] 3d compounds 1 H NMR, 13 C NMR such as Figure 7 ,like Figure 8As shown in the figure, the analysis results indicate that the target product obtained is correct.

[0119] The present invention also synthesized compound 3e-3i by the same method as in Example 1. The NMR data of compound 3e-3i are as follows. For the structural formula, yield, etc. of compound 3e-3i, please refer to Table 1.

[0120] Table 1. Structural formulas, yields, and NMR data of the synthesized compounds.

[0121]

[0122]

[0123]

[0124] Comparative Example 1:

[0125] The difference between Comparative Example 1 and Example 1 is that the electrode used in Comparative Example 1 for electrochemical catalytic oxidation is a graphite electrode.

[0126]

[0127] 4-Phenylacetyl styrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and a graphite electrode was used as both the anode and cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) at a ratio of 95:5 to obtain 4-([1,1'-biphenyl]-4-yl)-7-phenyl-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 21%.

[0128] Comparative Example 2:

[0129] The difference between Comparative Example 2 and Example 1 is that the electrode used in Comparative Example 2 for electrochemical catalytic oxidation is a platinum sheet electrode.

[0130]

[0131] 0.2 mmol of 4-phenylstyrene, 0.4 mmol of tetrabutylammonium hexafluorophosphate, 5 mL of acetonitrile, and 0.5 mL of water were added to a 10 mL reactor. A magnetic stir bar was added, and a platinum electrode was used as the anode and a graphite electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate in a volume ratio of 95:5 to obtain 4-([1,1'-biphenyl]-4-yl)-7-phenyl-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 44%.

[0132] Comparative Example 3:

[0133] The difference between Comparative Example 3 and Example 1 is that the electrode used in Comparative Example 3 for electrochemical catalytic oxidation is a copper sheet electrode.

[0134]

[0135] 0.2 mmol of 4-phenylstyrene, 0.4 mmol of tetrabutylammonium hexafluorophosphate, 5 mL of acetonitrile, and 0.5 mL of water were added to a 10 mL reactor. A magnetic stir bar was added, and a copper sheet electrode was used as the anode and a graphite electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. As the reaction proceeded, TLC showed no product formation. The conclusion of Comparative Example 3 is that the copper sheet electrode cannot catalyze the formation of 3,4-dihydronaphthyl-1(2H)-one compounds from styrene.

[0136] Comparative Example 4:

[0137] The difference between Comparative Example 4 and Example 1 is that the electrode used in Comparative Example 4 for electrochemical catalytic oxidation is a platinum nanoparticle electrode with a deposition time of 30 s.

[0138]

[0139] 4-Phenylacetyl styrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and a platinum nanoparticle electrode was used as the anode and a graphite electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) at a ratio of 95:5 to obtain 4-([1,1'-biphenyl]-4-yl)-7-phenyl-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 32%.

[0140] Comparative Example 5:

[0141] The difference between Comparative Example 5 and Example 1 is that the electrode used in Comparative Example 5 for electrochemical catalytic oxidation is a platinum nanoparticle electrode with a deposition time of 150 s.

[0142]

[0143] 4-Phenylacetyl styrene (0.2 mmol), tetrabutylammonium hexafluorophosphate (0.4 mmol), acetonitrile (5 mL), and water (0.5 mL) were added to a 10 mL reactor. A magnetic stir bar was added, and a platinum nanoparticle electrode was used as the anode and a graphite electrode as the cathode. The reaction was carried out under constant current electrolysis (7.5 mA) for 10 hours. The reaction was monitored by TLC. After the reaction was completed, 10 mL of saturated brine was added to the system, and the reaction was quenched by stirring. The mixture was extracted with ethyl acetate (10 mL × 3), and the organic phases were combined. The solvent was removed by rotary evaporation to obtain the crude product. The crude product was purified by column chromatography with silica gel loading and petroleum ether:ethyl acetate (v / v) at a ratio of 95:5 to obtain 4-([1,1'-biphenyl]-4-yl)-7-phenyl-3,4-dihydronaphthyl-1(2H)-one, a white solid with a separation yield of 70%.

[0144] As can be seen from Comparative Examples 1, 2, 3, 4, 5 and Example 1, the platinum nanoparticle electrode of the present invention, with appropriate deposition time and nanoparticle morphology and size to achieve suitable catalytic conditions, can effectively catalytically oxidize styrene derivatives.

[0145] Finally, it should be noted that the above comparative examples are actually comparative embodiments, and some of these comparative embodiments can also serve as the basis for the technical solutions protected by the claims of this invention. Furthermore, the above embodiments are only used to illustrate the technical solutions of this invention, and not to limit them; although this invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this invention.

Claims

1. An oxidative synthesis of dihydronaphthalene-1 from styrene and its derivatives ( 2H) The method for -ketones, characterized in that... include: In an electrochemical catalytic reactor, styrene and its derivatives are electrochemically catalytically oxidized to 3,4-dihydronaphth-1(2H)-one, as shown in the following reaction formula: The working electrode of the electrochemical catalytic reactor is a platinum nanoparticle electrode. In the reaction formula, R is independently selected from one of hydrogen, halogen, unsubstituted C1-10 alkyl, unsubstituted aryl, and unsubstituted C1-10 alkoxy.

2. The method according to claim 1, characterized in that, The electrolyte in the electrochemical catalytic reactor is an ammonium salt electrolyte or a lithium salt electrolyte.

3. The method according to claim 1, characterized in that, The electrochemical catalytic reaction is electrolyzed using either constant current or constant voltage methods, with the constant voltage range being 0~30V and the constant current range being 0~100mA.

4. The method according to claim 1, characterized in that, The concentration of styrene or styrene derivatives in the solvent is 0.001 mol / L to 0.5 mol / L.

5. The method according to claim 1, characterized in that, The reaction solution containing dihydronaphthyl-1(2H)-one obtained by electrochemical catalysis was concentrated, purified by silica gel column chromatography, and freeze-dried to obtain dihydronaphthyl-1(2H)-one.

6. The method according to claim 1, characterized in that, The platinum nanoparticle electrode is prepared by: Platinum nanoparticles are prepared on a substrate by isopotential electrodeposition in a platinum ion-containing deposition solution to obtain a platinum nanoparticle electrode.

7. The method according to claim 6, characterized in that, The substrate material is one or more of carbon paper, carbon felt, glassy carbon, nickel foam, and copper foam.

8. The method according to claim 6, characterized in that, The source of platinum in the sediment is one of platinum dichloride, chloroplatinic acid, potassium chloroplatinate, or dinitrosodiamineplatinum; the concentration of platinum ions is 0.01-100 mmol / L.

9. The method according to claim 6, characterized in that, The anions in the sediment are each independently selected from one or more of fluoride ions, chloride ions, bromide ions, iodide ions, nitrate ions, sulfate ions, perchlorate ions, and p-toluenesulfonate ions, and the concentration of the anions is 0.005-0.5 mol / L.

10. The method according to claim 6, characterized in that, The electrodeposition method selected is underpotential deposition, equal potential deposition, or overpotential deposition. The potential for electrodeposition is -0.5V to -1.2V, and the deposition time is between 10 and 300 seconds.

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