Method for directly preparing phenol and aldehyde or ketone from alkyl aromatic hydrocarbon as raw material on basis of selective carbon-carbon bond oxidative cleavage reaction

Abstract

Disclosed in the present invention is a method for directly preparing a phenol and an aldehyde or a ketone from an alkyl aromatic hydrocarbon as a raw material on the basis of a selective carbon-carbon bond oxidative cleavage reaction. The method is carried out on the basis of the following steps: mixing an alkyl aromatic hydrocarbon as represented by general formula (I) with a photocatalyst, hydrobromic acid, and an organic solvent and enabling the mixture to react under the conditions of oxygen as an oxidant and light irradiation to simultaneously prepare a phenol compound as represented by general formula (II) and a ketone or aldehyde compound as represented by general formula (III). In the present invention, bulk alkyl aromatic hydrocarbons are used as raw materials for reaction to produce phenol, aldehyde, and ketone organic chemical raw materials. Compared with traditional synthesis methods, the present invention has many advantages such as inexpensive and readily available catalysts, mild reaction conditions, simple operation, good selectivity, and high safety, is suitable for large-scale synthesis of phenols, p-cresol, cyclohexanone, etc., and exhibits wide application prospects.

Description

A method for the direct preparation of phenols and aldehydes or ketones from alkyl aromatics based on selective carbon-carbon bond oxidative cleavage reaction. Technical Field

[0001] This invention belongs to the field of fine chemical synthesis and application technology, and relates to a method for directly preparing phenols and aldehydes or ketones from alkyl aromatics based on selective carbon-carbon bond oxidative cleavage reaction. Background Technology

[0002] Aerobic oxidation of alkyl aromatics is an important pathway for converting them into high-value oxygen-containing products (such as alcohols, aldehydes, ketones, and carboxylic acids), and therefore has received continuous attention from academia and industry. For example, the catalytic oxidation of toluene and xylene in the presence of oxygen has been applied to the industrial production of benzoic acid and terephthalic acid. However, current research on these reactions mainly focuses on the oxidation of C-H bonds in the benzene ring side chains, while research on alkyl aromatic conversion reactions based on C-C bond oxidation is relatively scarce, especially for C(sp...) 2 )-C(sp 3 The oxidative cleavage reaction of C(sp) bonds. Developing carbon-carbon bond functionalization reactions offers a novel strategy for the high-value transformation of alkyl aromatics and is highly attractive, but realizing such processes faces numerous challenges. Among them, the main difficulty lies in the oxidative cleavage of C(sp) bonds. 2 )-C(sp 3 The bond dissociation energy of the C(sp) bond (98-100 kcal / mol) is higher than that of the C(sp) bond. 3 )-C(sp 3 ) bond (76-77 kcal / mol), and C(sp 2 )-C(sp 3 The ) bond is surrounded and blocked by more CH and C bonds, thus exhibiting thermodynamic stability and kinetic inertness, making its activation extremely difficult.

[0003] Carbon-carbon bond activation reactions are a major research focus in the fields of chemical industry and synthetic chemistry, offering potential methods for directly editing the carbon skeleton of molecules. Currently, there are numerous reports on the breaking of polar carbon-carbon bonds (such as carbon-cyano and carbon-carbonyl bonds). For the activation of nonpolar carbon-carbon bonds, two main approaches are employed: one is a ring-strain-releasing strategy involving opening smaller rings, and the other is β-carbon elimination assisted by chelating groups. Therefore, developing novel catalytic methods for the selective activation of nonpolar, unstrained carbon-carbon bonds is a cutting-edge scientific challenge in this field.

[0004] Oxidation reactions are an important component of synthetic chemistry, widely used in the production of fine chemicals such as pharmaceuticals and pesticides. Among numerous oxidants, oxygen is considered the cleanest and most ideal oxidant and oxygen atom donor. However, due to its weak oxidizing power, low reactivity, and the fact that stable ordinary oxygen is in the triplet state, which is subject to orbital confinement with most organic compounds, efficient oxidative transformation is difficult to achieve. How to achieve oxygen activation and oxidation under mild conditions is a cutting-edge scientific question for sustainable development. Molecular oxygen can be activated to generate reactive oxygen species (ROS), such as singlet oxygen (ROS). 1 Highly reactive oxidants such as O2, superoxide anion radicals (·O2-), hydroxyl radicals (·OH), and hydrogen peroxide (H2O2) are effective strategies for initiating desired oxidation reactions. Molecular oxygen activation can be achieved through traditional physical, chemical, and biological methods, but these methods suffer from drawbacks such as high energy consumption and low efficiency. In recent years, photocatalytic molecular oxygen activation has attracted widespread attention from researchers as a feasible strategy. Through photochemical action, spin-forbidden reactions can be broken, efficiently generating reactive oxygen species. Among them, singlet oxygen (… 1 O2 is a reactive oxygen species with selective oxidizing capabilities, and it has broad application prospects in the fields of environment and organic chemistry. Summary of the Invention

[0005] The problem the invention aims to solve

[0006] The primary objective of this invention is to provide a method for directly preparing corresponding phenols, aldehydes, or ketones from alkyl aromatic hydrocarbons based on a selective carbon-carbon bond oxidative cleavage reaction.

[0007] This preparation method has many advantages, such as inexpensive and readily available catalysts, mild reaction conditions, simple operation, good selectivity, and high safety. It is suitable for the large-scale synthesis of important organic chemical raw materials such as phenol, p-cresol, and cyclohexanone.

[0008] Solution for solving the problem

[0009] To achieve the above objectives, the present invention employs the following technical means:

[0010] This invention proposes a method for the direct preparation of phenols (II) and aldehydes or ketones (III) from alkyl aromatic hydrocarbons (I) based on selective carbon-carbon bond oxidative cleavage reactions. The method is carried out according to the following steps:

[0011] An alkyl aromatic hydrocarbon having general formula (I) is mixed with a photocatalyst, hydrobromic acid, and an organic solvent, and reacted under conditions of oxygen as the oxidant and light source irradiation to simultaneously produce phenolic compounds having general formula (II) and ketones or aldehydes having general formula (III); the method is shown in the following reaction formula (1):

[0012] Among them, R 1 This indicates a substituent group located on the benzene ring;

[0013] Among them, R 1 R 2 or R 3 R is independently selected from hydrogen, halogen, alkyl, aryl, substituted aryl, heterocyclic aryl, or substituted heterocyclic aryl. 1 R 2 or R 3 When they exist independently, they can be the same or different; or R 1 With R 2 R 2 With R 3 They combine to form cycloalkyl or substituted cycloalkyl groups;

[0014] Preferably, R 1 =R 2 = Hydrogen, R 3 = Hydrogen, methyl, pentyl, phenyl;

[0015] Preferably, R 1 = Hydrogen, methyl, R 2 =R 3 =Methyl;

[0016] Preferably, R 1 = Hydrogen, Bromine, R 2 and R 3 They combine to form a cyclohexyl group;

[0017] More preferably, the alkyl aromatic hydrocarbon represented by formula (I) is cyclohexylbenzene, 4-bromocyclohexylbenzene, cumene, or p-methylcumene.

[0018] The photocatalyst includes organic small molecule photocatalysts, transition metal photocatalysts, or heterogeneous photocatalysts.

[0019] Specifically, organic small molecule photocatalysts include, but are not limited to, photocatalysts of polycyano aromatic compounds (such as terephthalonitrile, 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile), photocatalysts of benzophenone compounds (such as benzophenone, azobenzoyl, 9-fluorenone, 4,5-diazonyl-9-one, thioxanthone), photocatalysts of quinone compounds (such as terebenzoquinone, 2,3-dichloro-5,6-dicyanobenzoquinone, anthraquinone), and fluorescein compounds. Photocatalysts (such as water-soluble eosin, eosin Y, sodium erythrosine B, sodium tetraiodofluorescein, eosin B, Bengal rose red), other small organic molecules (rhodamine, pyrans, phenthiazides, acridines, porphyrins) and compound photocatalysts (such as rhodamine 6G, 2,4,6-triphenylpyran tetrafluoride boron salt, methylene blue, 10-methyl-9-trimethylpyridine perchlorate, tetraphenylporphyrin); the transition metal photocatalysts of component (a) specifically include but... This is not limited to iridium photocatalysts (such as tris(2-phenylpyridine)iridium, tris[2-(2,4-difluorophenyl)pyridine]iridium), ruthenium photocatalysts (such as tris(2,2'-bipyridine)ruthenium dichloride, tris(2,2-bipyrimidine)ruthenium dichloride, tris(2,2'-bipyridine)ruthenium di(hexafluorophosphate)), and copper photocatalysts (such as bis(2,9-dimethyl-1,10-phenanthroline)copper dichloride, bis(2,9-diphenyl-1,10-... The heterogeneous photocatalyst of component (a) includes, but is not limited to, sodium decatungstate, titanium dioxide, quantum dot photocatalyst, and graphitic carbon nitride; preferably, anthraquinone, eosin Y, erythrosine B sodium salt, Bengal rose red, 9-fluorenone, and 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile.

[0020] The hydrobromic acid includes added hydrobromic acid or hydrobromic acid generated in situ during the reaction; the added hydrobromic acid includes an aqueous solution of hydrobromic acid, an organic solution of hydrobromic acid, a combination of bromide salts (lithium bromide, potassium bromide, sodium bromide, etc.) and protic acids (sulfuric acid, hydrochloric acid, nitric acid, methanesulfonic acid, trifluoromethanesulfonic acid, benzenesulfonic acid, p-toluenesulfonic acid monohydrate, etc.), or hydrogen bromide gas; the hydrobromic acid generated in situ during the reaction is hydrobromic acid generated in situ by the hydrogen atom transfer between bromine free radicals generated from bromine free radical precursors (including but not limited to N-bromosuccinimide, N-bromosaccharin, trichlorobromomethane, carbon tetrabromide, liquid bromine, alkyl bromides, or bromide salts) and alkyl aromatic hydrocarbons; preferably, it is an aqueous solution of hydrobromic acid.

[0021] The organic solvent includes one or more of 1,2-dichloroethane, 1,2-dibromoethane, 1,1-dibromomethane, dichloromethane, chloroform, carbon tetrachloride, acetonitrile, ethyl acetate, methyl acetate, butyl acetate, acetone, cyclohexanone, methanol, n-hexane, or cyclohexane; preferably, it is acetone, ethyl acetate, or n-hexane.

[0022] The source of the oxygen includes pure oxygen, oxygen in the air, or a mixture of oxygen and other gases; preferably, it is pure oxygen.

[0023] The light source is visible light or ultraviolet light; preferably, it is visible light (white light).

[0024] The molar ratio of the photocatalyst to hydrobromic acid is 1:20 to 1:1000; preferably, it is 1:200 to 1:500.

[0025] The molar ratio of the photocatalyst to the alkyl aromatic hydrocarbon having general formula (Ⅰ) is 1:100 to 1:10000; preferably, it is 1:1000 to 1:5000.

[0026] The volume ratio of the organic solvent to the alkyl aromatic hydrocarbon having general formula (I) is 1:2 to 1:60; preferably, it is 1:6 to 1:10.

[0027] The reaction time is 1-24 hours; preferably, it is 12 hours.

[0028] The reaction pressure is 0.1–10 MPa; preferably, it is atmospheric pressure.

[0029] The reaction temperature is 0–50°C; preferably, it is room temperature.

[0030] The reaction apparatus used in the method is a conventional photochemical reaction apparatus or a flow photochemical reaction apparatus.

[0031] The present invention also proposes a catalytic system comprising the following components: (a) a photocatalyst, (b) oxygen, and (c) hydrobromic acid;

[0032] For the carbon-carbon bond selective oxidation reaction of the aforementioned alkyl aromatics, a possible reaction mechanism is shown in Equation 2: Under illumination, the introduction of a photocatalyst significantly improves the light absorption efficiency of the system, acting as a medium to transfer light energy to oxygen (ET). The photocatalyst (PC) is excited to an excited state (PC*), and subsequently reacts with triplet oxygen (…). 3 O2 undergoes energy transfer to generate singlet oxygen (O2). 1O2). The oxidizing power of singlet oxygen is significantly enhanced compared to triplet oxygen. It can undergo a hydrogen atom transfer reaction (HAT) with hydrobromic acid (HBr) to form bromine radicals (Br·) and hydroperoxy radicals (HOO·). Bromine radicals can selectively and efficiently abstract hydrogen atoms from the benzyl position of alkyl aromatic hydrocarbons with general formula (I) to generate alkyl radicals (Int.1); these alkyl radicals can combine with hydroperoxy radicals to generate hydroperoxide intermediates (Int.2). Due to the acidic conditions of the reaction system, the hydroperoxide intermediates are protonated in situ once generated (Int.3), and then undergo a Hock rearrangement reaction to generate phenols with general formula (II) and ketones or aldehydes with general formula (III).

[0033] Among them, the photocatalyst of component (a) includes organic small molecule photocatalyst, transition metal photocatalyst, or heterogeneous photocatalyst.

[0034] Organic small molecule photocatalysts specifically include, but are not limited to, polycyano aromatic compound photocatalysts (such as terephthalonitrile, 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile), benzophenone photocatalysts (such as benzophenone, azobenzoyl, 9-fluorenone, 4,5-diazylfluoren-9-one, thioxanthone), quinone photocatalysts (such as p-benzoquinone, 2,3-dichloro-5,6-dicyanobenzoquinone, anthraquinone), and fluorescein photocatalysts (such as water-soluble eosin, eosin Y, erythrosine B sodium salt, tetraiodofluorescein). Photocatalysts include sodium fluorescein, eosin B, Bengal rose red, and other small organic molecules (rhodamine, pyran, phenthiazide, acridine, porphyrin) photocatalysts (such as rhodamine 6G, 2,4,6-triphenylpyran tetrafluoride boron salt, methylene blue, 10-methyl-9-trimethylpyridine perchlorate, tetraphenylporphyrin); the transition metal photocatalysts of component (a) specifically include, but are not limited to, iridium photocatalysts (such as tris(2-phenylpyridine)iridium, tris[2-(2,4-difluorophenyl)pyridine]iridium). Ruthenium metal photocatalysts (such as tris(2,2'-bipyridine)ruthenium dichloride, tris(2,2-bipyrimidine)ruthenium dichloride, tris(2,2'-bipyridine)ruthenium di(hexafluorophosphate)), copper metal photocatalysts (such as bis(2,9-dimethyl-1,10-phenanthroline)copper dichloride, bis(2,9-diphenyl-1,10-phenanthroline)cuprous chloride, bis(2,9-diphenyl-1,10-phenanthroline)copper dichloride), and iron metal photocatalysts (such as m-tetraphenylporphyrin ferric chloride); component (a) The heterogeneous photocatalyst specifically includes, but is not limited to, sodium decatungstate, titanium dioxide photocatalysts, quantum dot photocatalysts, and graphitic carbon nitride; preferably, it includes one or more of 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile, 9-fluorenone, anthraquinone, water-soluble eosin, eosin Y, sodium erythrosine B, sodium tetraiodofluorescein, eosin B, Bengal rose red, 2,4,6-triphenylpyran tetrafluoride boron salt, 10-methyl-9-trimethylpyridine perchlorate, titanium dioxide, or cadmium selenide.

[0035] Wherein, the source of oxygen in component (b) includes pure oxygen, oxygen in the air, or a mixture of oxygen and other gases; preferably, it is pure oxygen.

[0036] The hydrobromic acid in component (c) includes added hydrobromic acid or hydrobromic acid generated in situ during the reaction.

[0037] The added hydrobromic acid includes, but is not limited to, aqueous solutions of hydrobromic acid, organic solutions of hydrobromic acid, combinations of bromides and protic acids, or hydrogen bromide gas; the hydrobromic acid generated in situ by the reaction is hydrobromic acid generated in situ by the hydrogen atom transfer between bromine free radicals generated from bromine free radical precursors including N-bromosuccinimide, N-bromosaccharin, trichlorobromomethane, carbon tetrabromide, liquid bromine, alkyl bromides, or bromides and alkyl aromatic hydrocarbons.

[0038] The molar ratio of the photocatalyst to hydrobromic acid is 1:20 to 1:1000; preferably, it is 1:200 to 1:500.

[0039] The catalyst system is used for the selective oxidation of carbon-carbon bonds in alkyl aromatics.

[0040] The present invention also proposes the application of the catalyst system in the selective oxidation of carbon-carbon bonds in alkyl aromatics.

[0041] The selective oxidation reaction of carbon-carbon bonds of alkyl aromatics refers to the reaction of directly preparing the corresponding phenols, ketones or aldehydes from alkyl aromatics.

[0042] The amount of hydrobromic acid directly added and the hydrobromic acid generated in situ in this invention play a crucial role in realizing the carbon-carbon bond selective oxidation reaction of the alkyl aromatic hydrocarbons: on the one hand, because hydrobromic acid has a suitable bond dissociation energy (Figure 1), bromine radicals can selectively extract hydrogen from the benzyl position to give alkyl radicals; on the other hand, because hydrobromic acid is a strong acid, it can catalyze the rearrangement reaction of hydroperoxide intermediates in situ.

[0043] In addition, the addition of photocatalysts can greatly improve the conversion efficiency of the reaction: First, under light conditions, the efficiency of directly generating bromine radicals from hydrobromic acid is very low. By introducing photocatalysts, the efficient generation of singlet oxygen can be achieved through energy transfer, thereby promoting the efficient generation of bromine radicals (Figure 2); Second, the hydroperoxide radicals generated by the hydrogen atom transfer between singlet oxygen and hydrobromic acid can quickly capture alkyl radicals, achieving the efficient generation of hydroperoxides (Figure 3).

[0044] The effects of the invention

[0045] The beneficial effects of this invention include, but are not limited to:

[0046] 1. This invention is the first to use alkyl aromatics as raw materials and utilizes the developed photocatalytic selective oxidation and cleavage reaction of carbon-carbon bonds to directly prepare the corresponding phenols, aldehydes or ketones.

[0047] 2. Compared with traditional synthesis methods, the method of the present invention has many advantages, such as economical and readily available catalysts, mild reaction conditions, no need for metal participation, and simple operation.

[0048] This technology has great potential for large-scale production of phenol, p-phenol, and cyclohexanone. Based on this invention, a new process can be developed to directly produce phenol and co-produce cyclohexanone from cyclohexylbenzene in a one-step process. This new process has the advantages of a short process flow and high selectivity. Attached Figure Description

[0049] Figure 1 shows a schematic diagram of the bond dissociation energy investigated in this invention.

[0050] Figure 2 shows a comparison of the energy of hydrogen atom transfer between oxygen and hydrobromic acid with different electronic configurations.

[0051] Figure 3 shows a comparison of the energies of different pathways for the formation of cyclohexylbenzene-1-hydroperoxide.

[0052] Figure 4 shows the NMR spectrum of the cyclohexylbenzene reaction monitoring. Detailed Implementation

[0053] The present invention will be further described below with reference to specific embodiments, and the advantages and features of the present invention will become clearer with the description. However, the embodiments are merely exemplary and do not constitute any limitation on the scope of the present invention. Those skilled in the art should understand that modifications or substitutions can be made to the details and form of the technical solutions of the present invention without departing from the spirit and scope of the present invention, but all such modifications and substitutions fall within the protection scope of the present invention.

[0054] Example 1—Blank Control Experiment

[0055] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. One of the following was added sequentially to the reaction system: anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), acetone (1.0 mL), or white LED lamp (60 W). After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a coarse NMR spectrometer. The results are shown in Table 1. The experimental results show that the reaction can proceed smoothly with a high conversion rate only when the photocatalyst, hydrobromic acid solution, reaction solvent and light are present in the system at the same time. When there is no photocatalyst or reaction solvent in the system, the formation of the product will be severely inhibited, and when there is no hydrobromic acid solution or light in the system, the reaction cannot proceed.

[0056] Table 1

[0057] Example 2—Control Experiment

[0058] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask, and the effects of different hydrobromic acid sources (3.6 mmol) were investigated. After purging the reaction flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a coarse NMR spectrometer. The results are shown in Table 2. The experimental results show that no reaction occurred when only bromide and water were added; when hydrobromic acid was generated in situ using a combination of bromide and protic acid, the reaction proceeded normally, but the conversion rate was low, while the addition of deionized water significantly promoted the reaction.

[0059] Table 2

[0060] Example 3—Reaction of Cyclohexylbenzene

[0061] a) Cyclohexylbenzene (6.0 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 25.8%, the yield of cyclohexanone was 22.2%, and the conversion of cyclohexylbenzene was 27.5%.

[0062] (b) Cyclohexylbenzene (6.1 mL), azobenzoic acid (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.3%, the yield of cyclohexanone was 3.3%, and the conversion of cyclohexylbenzene was 5.5%.

[0063] c) Cyclohexylbenzene (6.1 mL), 9-fluorenone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 24.6%, the yield of cyclohexanone was 20.4%, and the conversion of cyclohexylbenzene was 27%.

[0064] d) Cyclohexylbenzene (6.1 mL), eosin Y (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 24.6%, the yield of cyclohexanone was 21.4%, and the conversion of cyclohexylbenzene was 27.1%.

[0065] e) Cyclohexylbenzene (6.1 mL), aqueous eosin (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 18%, the yield of cyclohexanone was 16%, and the conversion of cyclohexylbenzene was 21%.

[0066] f) Cyclohexylbenzene (6.1 mL), eosin B (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 15%, the yield of cyclohexanone was 13%, and the conversion of cyclohexylbenzene was 18%.

[0067] g) Cyclohexylbenzene (6.1 mL), sodium tetraiodofluorescein (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 24.6%, the yield of cyclohexanone was 20.2%, and the conversion of cyclohexylbenzene was 31%.

[0068] h) Cyclohexylbenzene (6.1 mL), Bengal rose red (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 22.4%, the yield of cyclohexanone was 18%, and the conversion of cyclohexylbenzene was 32%.

[0069] i) Cyclohexylbenzene (6.1 mL), erythrosine B sodium salt (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the reaction flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 24.3%, the yield of cyclohexanone was 19.4%, and the conversion of cyclohexylbenzene was 31%.

[0070] j) Cyclohexylbenzene (6.1 mL), 2,4,5,6-tetrakis(9-carbazolyl)-isophthalonitrile (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 24.6%, the yield of cyclohexanone was 20%, and the conversion of cyclohexylbenzene was 29%.

[0071] k) Cyclohexylbenzene (6.1 mL), rhodamine 6 G (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.2%, the yield of cyclohexanone was 3.2%, and the conversion of cyclohexylbenzene was 5.5%.

[0072] 1) Cyclohexylbenzene (6.1 mL), 2,4,6-triphenylpyran tetrafluoride boron salt (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 5.5%, the yield of cyclohexanone was 5.3%, and the conversion of cyclohexylbenzene was 6%.

[0073] In a reaction flask, cyclohexylbenzene (6.1 mL), methylene blue (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 3.7%, the yield of cyclohexanone was 2.8%, and the conversion of cyclohexylbenzene was 4.0%.

[0074] In a reaction flask, cyclohexylbenzene (6.1 mL), 10-methyl-9-trimethylmethylacridinium perchlorate (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 3.6%, the yield of cyclohexanone was 2.2%, and the conversion of cyclohexylbenzene was 4.4%.

[0075] In a reaction flask, cyclohexylbenzene (6.1 mL), tetraphenylporphyrin (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 2.0%, the yield of cyclohexanone was 1.5%, and the conversion of cyclohexylbenzene was 2.6%.

[0076] p) Cyclohexylbenzene (6.1 mL), tris(2-phenylpyridinium)iridium (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.5%, the yield of cyclohexanone was 3.9%, and the conversion of cyclohexylbenzene was 5.6%.

[0077] q) Cyclohexylbenzene (6.1 mL), tris(2,2-bipyrimidine)ruthenium dichloride (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 3.5%, the yield of cyclohexanone was 2.8%, and the conversion of cyclohexylbenzene was 4.7%.

[0078] r) Cyclohexylbenzene (6.1 mL), bis(2,9-dimethyl-1,10-phenanthroline)copper dichloride (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 2.8%, the yield of cyclohexanone was 2.1%, and the conversion of cyclohexylbenzene was 5.0%.

[0079] s) Cyclohexylbenzene (6.1 mL), m-tetraphenylporphyrin ferric chloride (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the reaction flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 3.6%, the yield of cyclohexanone was 3.0%, and the conversion of cyclohexylbenzene was 4.8%.

[0080] Cyclohexylbenzene (6.1 mL), cadmium selenide quantum dots (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 2.6%, the yield of cyclohexanone was 2.2%, and the conversion of cyclohexylbenzene was 4%.

[0081] u) Cyclohexylbenzene (6.1 mL), titanium dioxide (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.6%, the yield of cyclohexanone was 3.4%, and the conversion of cyclohexylbenzene was 6%.

[0082] v) Cyclohexylbenzene (6.1 mL), sodium decatungstate (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 2.0%, the yield of cyclohexanone was 1.2%, and the conversion of cyclohexylbenzene was 3.0%.

[0083] In a reaction flask, 6.1 mL of cyclohexylbenzene, 0.0072 mmol of graphitic carbon nitride, 0.6 mL of hydrobromic acid solution (40 wt.% aqueous solution), and 1.0 mL of acetone were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a 60 W white LED lamp for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with 0.5 mL of deuterated chloroform before being sent to a crude NMR spectrometer. The yields of phenol and cyclohexanone were 1.0%, and the conversion of cyclohexylbenzene was 2.6%.

[0084] x) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0036 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 7.0%, the yield of cyclohexanone was 6.4%, and the conversion of cyclohexylbenzene was 7.7%.

[0085] y) Cyclohexylbenzene (6.1 mL), anthraquinone (0.018 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 27.5%, the yield of cyclohexanone was 23.5%, and the conversion of cyclohexylbenzene was 29.9%.

[0086] z) Cyclohexylbenzene (6.1 mL), anthraquinone (0.18 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 20.9%, the yield of cyclohexanone was 16.4%, and the conversion of cyclohexylbenzene was 24.3%.

[0087] aa) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a green LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 25.3%, the yield of cyclohexanone was 20.7%, and the conversion of cyclohexylbenzene was 28%.

[0088] ab) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a blue LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 26%, the yield of cyclohexanone was 22%, and the conversion of cyclohexylbenzene was 30%.

[0089] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under UV light (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 10%, the yield of cyclohexanone was 6.1%, and the conversion of cyclohexylbenzene was 17%.

[0090] In the reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (30 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 6%, the yield of cyclohexanone was 4.9%, and the conversion of cyclohexylbenzene was 6.1%.

[0091] In reaction flask ablation, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (90 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 25.4%, the yield of cyclohexanone was 19.7%, and the conversion of cyclohexylbenzene was 29.2%.

[0092] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.3 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 17.4%, the yield of cyclohexanone was 13.9%, and the conversion of cyclohexylbenzene was 19.3%.

[0093] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.9 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 6.1%, the yield of cyclohexanone was 4.8%, and the conversion of cyclohexylbenzene was 6.7%.

[0094] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to a reaction flask. The flask was then purged with an oxygen atmosphere and an air balloon was inserted. The flask was then placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 6.7%, the yield of cyclohexanone was 5.3%, and the conversion of cyclohexylbenzene was 7.6%.

[0095] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere and a balloon was inserted (N2:O2 = 1:1). The flask was then placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 12.5%, the yield of cyclohexanone was 10.9%, and the conversion of cyclohexylbenzene was 13%.

[0096] a) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere and an oxygen bulb was inserted (N2:O2 = 4:1). The flask was then placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.5%, the yield of cyclohexanone was 3.9%, and the conversion of cyclohexylbenzene was 6%.

[0097] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and ethyl acetate (1.0 mL) were added sequentially to a reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 25.3%, the yield of cyclohexanone was 20.8%, and the conversion of cyclohexylbenzene was 37.7%.

[0098] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetonitrile (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 18.6%, the yield of cyclohexanone was 12.7%, and the conversion of cyclohexylbenzene was 22%.

[0099] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and dichloromethane (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 3.5%, the yield of cyclohexanone was 1.1%, and the conversion of cyclohexylbenzene was 6.2%.

[0100] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and cyclohexanone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 1.4%, and the conversion of cyclohexylbenzene was 1.8%.

[0101] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and methanol (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the reaction was carried out under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 1.8%, the yield of cyclohexanone was 0.9%, and the conversion of cyclohexylbenzene was 2.5%.

[0102] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and cyclohexane (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the reaction was carried out under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 24.2%, the yield of cyclohexanone was 18%, and the conversion of cyclohexylbenzene was 28%.

[0103] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The reaction flask was purged with oxygen at 1 MPa and then placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 24.8%, the yield of cyclohexanone was 20.6%, and the conversion of cyclohexylbenzene was 28.9%.

[0104] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to a reaction flask. The reaction flask was then purged with oxygen at 5 MPa and placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 26.5%, the yield of cyclohexanone was 21.1%, and the conversion of cyclohexylbenzene was 30.8%.

[0105] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. The reaction flask was then purged with an oxygen atmosphere at 10 MPa and placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 27.1%, the yield of cyclohexanone was 22.0%, and the conversion of cyclohexylbenzene was 32.4%.

[0106] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to a reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at 0 °C using a constant temperature reaction bath. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yields of phenol and cyclohexanone were 3.3%, 3.2%, and 3.8% of cyclohexylbenzene were converted.

[0107] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to a reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at 15 °C using a constant temperature reaction bath. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 13.0%, the yield of cyclohexanone was 12.6%, and the conversion of cyclohexylbenzene was 14.2%.

[0108] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to a reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at 40 °C using a constant temperature reaction bath. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 11.1%, the yield of cyclohexanone was 10.1%, and the conversion of cyclohexylbenzene was 11.6%.

[0109] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the reaction temperature controlled at 50 °C using a constant temperature reaction bath. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 6.8%, the yield of cyclohexanone was 5.4%, and the conversion of cyclohexylbenzene was 7.7%.

[0110] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the mixture was placed under a white LED lamp (60 W) for 6 hours, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yields of phenol and cyclohexanone were 13.1%, 11.9%, and 13.9% of cyclohexylbenzene were converted.

[0111] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 9 hours, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 22.2%, the yield of cyclohexanone was 19.0%, and the conversion of cyclohexylbenzene was 23.5%.

[0112] In a reaction flask, cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the reaction was carried out under a white LED lamp (60 W) for 15 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 27.0%, the yield of cyclohexanone was 22.0%, and the conversion of cyclohexylbenzene was 31.6%.

[0113] Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 24 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 27.1%, the yield of cyclohexanone was 22.2%, and the conversion of cyclohexylbenzene was 34%.

[0114] Example 4—Reaction of Cyclohexylbenzene

[0115] a) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), sodium bromide (4 mmol), concentrated sulfuric acid (0.2 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 4.4%, the yield of cyclohexanone was 3.1%, and the conversion of cyclohexylbenzene was 6.7%.

[0116] (b) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), potassium bromide (4 mmol), concentrated sulfuric acid (0.2 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 2.8%, the yield of cyclohexanone was 2.2%, and the conversion of cyclohexylbenzene was 5.1%.

[0117] c) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), concentrated hydrochloric acid (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 9.0%, the yield of cyclohexanone was 8.2%, and the conversion of cyclohexylbenzene was 9.1%.

[0118] d) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), concentrated nitric acid (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 3.1%, the yield of cyclohexanone was 1.9%, and the conversion of cyclohexylbenzene was 3.9%.

[0119] e) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), methanesulfonic acid (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 8.4%, the yield of cyclohexanone was 6.1%, and the conversion of cyclohexylbenzene was 10.3%.

[0120] f) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), trifluoromethanesulfonic acid (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 2.2%, the yield of cyclohexanone was 1.6%, and the conversion of cyclohexylbenzene was 3.5%.

[0121] g) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), benzenesulfonic acid (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 5.0%, the yield of cyclohexanone was 4.2%, and the conversion of cyclohexylbenzene was 7.2%.

[0122] h) Cyclohexylbenzene (6.1 mL), anthraquinone (0.0072 mmol), lithium bromide (4 mmol), p-toluenesulfonic acid monohydrate (4 mmol), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 7.0%, the yield of cyclohexanone was 6.0%, and the conversion of cyclohexylbenzene was 8.2%.

[0123] Example 5—Reaction of Cyclohexylbenzene

[0124] Cyclohexylbenzene (6.1 mL), liquid bromine (0.36 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectrometer. The yield of phenol was 4.6%, the yield of cyclohexanone was 4.1%, and the conversion of cyclohexylbenzene was 7.6%.

[0125] Example 6—Reaction of Cyclohexylbenzene

[0126] a) Cyclohexylbenzene (CHB, 1.0 mL, 6.0 mmol), carbon tetrabromide (0.6 mmol), and acetonitrile (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under different light sources (60 W) for 12 h, with the reaction temperature controlled at room temperature using a fan. After the reaction was complete, the solution was passed through a 1 cm silica gel (100–200 mesh) short column and eluted with 50 mL of ethyl acetate. After removing the solvent, dibromomethane (210 μL, 3.0 mmol) and deuterated chloroform (1 mL) were added to the residue. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 10.1%, the yield of cyclohexanone was 3.6%, and the conversion of cyclohexylbenzene was 18.5%.

[0127] b) Cyclohexylbenzene (CHB, 1.0 mL, 6.0 mmol), N-bromosuccinimide (0.6 mmol), and acetonitrile (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under different light sources (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, the solution was eluted with 50 mL of ethyl acetate through a 1 cm silica gel (100–200 mesh) short column. After removing the solvent, dibromomethane (210 μL, 3.0 mmol) and deuterated chloroform (1 mL) were added to the residue. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 1.9%, the yield of cyclohexanone was 1.4%, and the conversion of cyclohexylbenzene was 5.2%.

[0128] Example 7—Scale-up reaction of cyclohexylbenzene

[0129] Cyclohexylbenzene (CHB, 169.0 mL, 1000.0 mmol), anthraquinone (0.2 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 8.4 mL), and acetone (28.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bag was inserted, and the flask was placed under a white LED lamp (90 W) for irradiation. The temperature was maintained at room temperature using a fan, and mechanical stirring was used to ensure homogeneous mixing of the reaction mixture. After 15 h of reaction, 0.5 mL of the reaction mixture was collected and allowed to stand. 0.2 mL of the supernatant was then collected and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 23.2%, the yield of cyclohexanone was 21.8%, and the conversion of 4-bromocyclohexylbenzene was 24.4%.

[0130] Example 8—Reaction of Cyclohexylbenzene Using a Flow Photochemical Device

[0131] Cyclohexylbenzene (CHB, 12.0 mL, 72.0 mmol), eosin Y (0.0144 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 1.2 mL), and acetone (2.0 mL) were added sequentially to the reaction flask. The flask was connected to a flow purging device for circulation (80 mL / min), and after purging to an oxygen atmosphere, an oxygen bulb was inserted. The flask was then placed under a white LED lamp (90 W) for 12 hours, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a coarse NMR spectrometer. The yield of phenol was 23.7%, the yield of cyclohexanone was 19.7%, and the conversion of cyclohexylbenzene was 24%. The experimental results indicate that the 72 mmol specification reaction can proceed normally in a mobile phase apparatus.

[0132] Example 9—Reaction of 4-bromocyclohexylbenzene

[0133] 4-Bromocyclohexylbenzene (7.0 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of p-bromophenol was 16.5%, the yield of cyclohexanone was 13.4%, and the conversion of 4-bromocyclohexylbenzene was 17.8%.

[0134] Example 10—Reaction of Cumene

[0135] Cumene (5.0 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 11.5%, and the conversion of cumene was 12%.

[0136] Example 11—Reaction of p-methylisopropylbenzene

[0137] In a reaction flask, p-methylisopropylbenzene (5.6 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially. The flask was then purged with an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature maintained at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of p-methylphenol was 3.7%, and the conversion of 4-bromocyclohexylbenzene was 4%.

[0138] Example 12—Reaction of ethylbenzene

[0139] Ethylbenzene (4.5 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 2.3%, the yield of acetaldehyde was 1.0%, and the conversion of ethylbenzene was 2.5%.

[0140] Example 13—Reaction of Hexylbenzene

[0141] Hexylbenzene (6.8 mL, 36.0 mmol), anthraquinone (0.0072 mmol), hydrobromic acid solution (40 wt.% aqueous solution, 0.6 mL), and acetone (1.0 mL) were added sequentially to the reaction flask. After purging the flask to an oxygen atmosphere, an oxygen bulb was inserted, and the flask was placed under a white LED lamp (60 W) for 12 h, with the temperature controlled at room temperature using a fan. After the reaction was complete, 0.2 mL of the reaction solution was taken and dibromomethane (35 μL, 0.5 mmol) and deuterated chloroform (0.5 mL) were added. After mixing, 100 μL of the mixture was transferred to an NMR tube and diluted with deuterated chloroform (0.5 mL) before being sent to a crude NMR spectroscopy. The yield of phenol was 1.0%, the yield of hexanal was 0.5%, and the conversion of hexylbenzene was 1.2%.

[0142] The scope of protection of this invention is not limited to the above embodiments. Any variations and advantages that can be conceived by those skilled in the art without departing from the spirit and scope of this invention are included in this invention and are protected by the appended claims.

Claims

1. A method for the direct preparation of phenols (II) and aldehydes or ketones (III) from alkyl aromatic hydrocarbons (I) based on selective carbon-carbon bond oxidative cleavage reaction, characterized in that, The method includes the following steps: mixing an alkyl aromatic hydrocarbon having general formula (I) with a photocatalyst, hydrobromic acid, and an organic solvent, and reacting it under conditions of oxygen as the oxidant and light source irradiation, thereby simultaneously preparing a phenolic compound having general formula (II) and a ketone or aldehyde compound having general formula (III); the method is shown in the following reaction formula (1): Among them, R 1 This indicates a substituent group located on the benzene ring; R 1 R 2 Or R 3 R is independently selected from hydrogen, halogen, alkyl, aryl, substituted aryl, heterocyclic aryl, or substituted heterocyclic aryl. 1 R 2 Or R 3 When they exist independently, they can be the same or different; or R 1 With R 2 R 2 With R 3 They combine to form cycloalkyl or substituted cycloalkyl groups.

2. The method as described in claim 1, characterized in that, The photocatalyst includes organic small molecule photocatalysts, transition metal photocatalysts, or heterogeneous photocatalysts. And / or, the hydrobromic acid includes added hydrobromic acid or hydrobromic acid generated in situ during the reaction; And / or, the organic solvent includes one or more of 1,2-dichloroethane, 1,2-dibromoethane, 1,1-dibromomethane, dichloromethane, chloroform, carbon tetrachloride, acetonitrile, ethyl acetate, methyl acetate, butyl acetate, acetone, cyclohexanone, methanol, n-hexane, or cyclohexane. And / or, the source of the oxygen includes pure oxygen, oxygen in the air, or a mixture of oxygen and other gases; And / or, the light source is visible light or ultraviolet light.

3. The method as described in claim 2, characterized in that, The organic small molecule photocatalysts include polycyano aromatic compound photocatalysts, benzophenone compound photocatalysts, quinone compound photocatalysts, fluorescein compound photocatalysts, rhodamine compound photocatalysts, pyran compound photocatalysts, phenthiazide compound photocatalysts, acridine compound photocatalysts, and porphyrin compound photocatalysts; and / or, the transition metal photocatalysts include iridium metal photocatalysts, ruthenium metal photocatalysts, copper metal photocatalysts, and iron metal photocatalysts; and / or, the heterogeneous photocatalysts include sodium decatungstate, titanium dioxide, quantum dot photocatalysts, and graphitic carbon nitride. And / or, the added hydrobromic acid includes an aqueous solution of hydrobromic acid, an organic solution of hydrobromic acid, a combination of bromide salt and protic acid, or hydrogen bromide gas; And / or, the hydrobromic acid produced in situ by the reaction is hydrobromic acid produced in situ by the hydrogen atom transfer between the bromine free radical generated from the bromine free radical precursor and the alkyl aromatic hydrocarbon.

4. The method as described in claim 3, characterized in that, The photocatalyst comprises terephthalonitrile, 2,4,5,6-tetra(9-carbazolyl)-isophthalonitrile, benzophenone, azobenzoyl, 9-fluorenone, 4,5-diazylfluoren-9-one, thioxanone, terequinone, 2,3-dichloro-5,6-dicyanobenzoquinone, anthraquinone, water-soluble eosin, eosin Y, sodium erythrosine B, sodium tetraiodofluorescein, eosin B, Bengal rose red, rhodamine 6G, 2,4,6-triphenylpyran tetrafluoride boron salt, methylene blue, 10-methyl-9-trimethylpyridine perchlorate, tetraphenyl One or more of the following: porphyrin tris(2-phenylpyridine)iridium, tris[2-(2,4-difluorophenyl)pyridine]iridium, tris(2,2'-bipyridine)ruthenium dichloride, tris(2,2-bipyrimidine)ruthenium dichloride, tris(2,2'-bipyridine)ruthenium di(hexafluorophosphate), bis(2,9-dimethyl-1,10-phenanthroline)copper dichloride, bis(2,9-diphenyl-1,10-phenanthroline)cuprous chloride, bis(2,9-diphenyl-1,10-phenanthroline)copper dichloride, and m-tetraphenylporphyrin ferric chloride; And / or, the bromine radical precursor includes N-bromosuccinimide, N-bromosaccharin, trichlorobromomethane, carbon tetrabromide, liquid bromine, alkyl bromide, or bromide salt.

5. The method as described in claim 1, characterized in that, The molar ratio of the photocatalyst to hydrobromic acid is 1:20 to 1:1000; and / or, the molar ratio of the photocatalyst to an alkyl aromatic hydrocarbon having general formula (I) is 1:100 to 1:10000; and / or, the volume ratio of the organic solvent to an alkyl aromatic hydrocarbon having general formula (I) is 1:2 to 1:

60.

6. The method as described in claim 1, characterized in that, The reaction time is 1-24 hours; and / or the reaction pressure is 0.1-10 MPa; and / or the reaction temperature is 0-50°C.

7. The method as described in claim 1, characterized in that, Alkyl aromatics having the general formula (I) are selected from compounds in the following group: (1)R 1 =R 2 = Hydrogen, R 3 = Hydrogen, methyl, pentyl, phenyl; or, (2)R 1 = Hydrogen, methyl, R 2 =R 3 =Methyl; or, (3)R 1 = Hydrogen, Bromine, R 2 and R 3 They combine to form a cyclohexyl group.

8. A catalytic system, characterized in that, The catalytic system comprises (a) a photocatalyst, (b) oxygen, and (c) hydrobromic acid; wherein the catalytic mechanism of the catalytic system is as follows: the introduction of the photocatalyst significantly improves the light absorption efficiency of the system, acting as a medium to transfer light energy to oxygen (ET), thereby converting triplet oxygen (ET) into hydrogen ions. 3 O2) is excited into singlet oxygen ( 1 O2); the oxidizing power of the singlet oxygen is significantly enhanced compared to the triplet oxygen, and it undergoes a hydrogen atom transfer reaction (HAT) with hydrobromic acid to generate bromine free radicals (Br). . ) and hydroperoxygen radicals (HOO) . The bromine radical can selectively and efficiently abstract a hydrogen atom from the benzyl position of an alkyl aromatic hydrocarbon having general formula (I) to generate an alkyl radical (Int.1); the generated alkyl radical combines with a hydroperoxide radical to generate a hydroperoxide (Int.2); under acidic reaction conditions, once the hydroperoxide intermediate is generated, it is protonated in situ (Int.3) and generates the corresponding phenol having general formula (II) and ketone or aldehyde having general formula (III) through a Hock rearrangement reaction; the catalytic mechanism is shown in the following reaction formula (2):

9. The catalytic system as described in claim 8, characterized in that, The photocatalyst includes an organic small molecule photocatalyst, a transition metal photocatalyst, or a heterogeneous photocatalyst; and / or, the hydrobromic acid includes added hydrobromic acid or hydrobromic acid generated in situ during the reaction; and / or, the source of the oxygen includes pure oxygen, oxygen in the air, or a mixture of oxygen and other gases; and / or, the molar ratio of the photocatalyst to hydrobromic acid is 1:20 to 1:1000.

10. The application of the catalytic system as described in claim 8 or 9 in the selective oxidative cleavage of carbon-carbon bonds in alkyl aromatics.

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