A preparation method of 2-methyl-1,4-naphthoquinone and its intermediates

Abstract

The invention discloses a method for preparing 2-methyl-1,4-naphthoquinone and an intermediate thereof. The method for preparing the intermediate 2-methyl-1,4-tetrahydronaphthoquinone comprises: allowing o-methylbenzoquinone and 1,3-butadiene to undergo an addition reaction under the catalytic action of a metal chelate ionic liquid represented by formula (I) to generate 2-methyl-1,4-tetrahydronaphthoquinone, wherein a, b, c, and d are independently 0, 1, or 2, respectively. The method can efficiently and selectively obtain 2-methyl-1,4-tetrahydronaphthoquinone and can be used for the preparation of 2-methyl-1,4-naphthoquinone. #imgabs0#

Description

Technical Field

[0001] The invention relates to the technical field of fine chemical synthesis, and in particular to a method for preparing 2-methyl-1,4-naphthoquinone and an intermediate thereof. Background Art

[0002] Vitamin K3, also known as menadione, or 2-methyl-1,4-naphthoquinone, is an organic compound that can be derived to prepare vitamin K1, K2 and other K vitamins. Vitamin K is a procoagulant in clinical practice and can be used to treat hemorrhagic diseases caused by vitamin K deficiency. It is also used in various foods, beverages and dietary supplements. It helps the body to coagulate blood and maintain bone health, and is of great significance to life and health. Vitamin K3 is the main K vitamin produced in industry.

[0003] At present, with the development trend of green production, a production route using methyl benzoquinone as an intermediate has been proposed. This route generally involves three steps: p-cresol is oxidized by tert-butyl hydrogen peroxide to obtain o-methyl benzoquinone (also known as o-methyl p-benzoquinone, 2-methyl p-benzoquinone, methyl-1,4-benzoquinone), o-methyl benzoquinone and 1,3-butadiene are reacted by Diels-Alder reaction catalyzed by scandium trifluoromethanesulfonate to obtain 2-methyl-1,4-tetrahydronaphthoquinone, and then dehydrogenated under palladium carbon catalysis to obtain vitamin K3. The Diels-Alder reaction in this route uses scandium trifluoromethanesulfonate, which uses the scandium element, which is expensive and not conducive to large-scale industrial application.

[0004] At the same time, a new production process for producing 2-methyl-1,4-naphthoquinone from o-cresol is also disclosed, which uses 50% hydrogen peroxide to oxidize o-cresol in a microchannel reactor, performs a Diels-Alder reaction under a pressurized environment, and uses DMSO (dimethyl sulfoxide) as a solvent and an oxidant to oxidize 2-methyl-1,4-tetrahydronaphthoquinone under a copper bromide / manganese bromide mixed catalyst system. The Diels-Alder reaction in this method requires excessive addition of 1,3-butadiene, and the reaction uses a pressurized environment. The conditions are relatively harsh and there are safety hazards. It is also time-consuming. It has been verified that if the Diels-Alder reaction in this method is carried out under normal pressure, the result is that the conversion rate and yield are both low, which is not conducive to industrial production. Summary of the invention

[0005] The object of the present invention is to overcome one or more deficiencies of the prior art and to provide an improved method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (an intermediate of 2-methyl-1,4-naphthoquinone), which can obtain 2-methyl-1,4-tetrahydronaphthoquinone efficiently, highly selectively and relatively safely.

[0006] The present invention also provides a preparation process of 2-methyl-1,4-naphthoquinone, which comprises the above-mentioned method for preparing 2-methyl-1,4-tetrahydronaphthoquinone.

[0007] To achieve the above object, a technical solution adopted by the present invention is: a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone, the preparation method comprising: allowing o-methylbenzoquinone to undergo an addition reaction with 1,3-butadiene to generate 2-methyl-1,4-tetrahydronaphthoquinone, the reaction formula being:

[0008] in:

[0009] The addition reaction is carried out under the catalytic action of the metal chelate ionic liquid represented by formula (I);

[0010] a, b, c, and d are each independently 0, 1, or 2.

[0011] According to some preferred and specific aspects of the present invention, the values ​​of a, b, c and d are the same.

[0012] According to a specific aspect of the present invention, the metal chelate ionic liquid (Chelate-Cu-IL) represented by formula (I) is:

[0013]

[0014] According to some preferred aspects of the present invention, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methylbenzoquinone is 1:5-5000.

[0015] Furthermore, the molar ratio of the metal chelate ionic liquid represented by the formula (I) to the o-methylbenzoquinone is 1:5-2500.

[0016] Furthermore, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methylbenzoquinone is 1:5-2000.

[0017] Furthermore, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methylbenzoquinone is 1:5-1000.

[0018] In some preferred and specific embodiments of the present invention, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methylbenzoquinone is 1:5-500.

[0019] In some embodiments of the present invention, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methyl benzoquinone is 1:10-5000. Further, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methyl benzoquinone is 1:10-2500. Further, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methyl benzoquinone is 1:10-2000. Further, the molar ratio of the metal chelate ionic liquid represented by formula (I) to the o-methyl benzoquinone is 1:10-1000.

[0020] According to the present invention, under the catalytic action of the metal chelate ionic liquid of the present invention, the addition reaction can be carried out at a relatively low temperature; in some embodiments of the present invention, the reaction temperature of the addition reaction is 0-80°C, and further, can be carried out at 0-70°C.

[0021] According to the present invention, under the catalytic action of the metal chelate ionic liquid of the present invention, the reaction pressure of the addition reaction can be normal pressure, and no pressure treatment is required. The ideal product yield can be obtained by carrying out the reaction under normal pressure.

[0022] According to the present invention, under the catalysis of the metal chelate ionic liquid of the present invention, the molar ratio of o-methyl benzoquinone to 1,3-butadiene can be 1:0.95-1.05. According to a specific aspect of the present invention, the molar ratio of o-methyl benzoquinone to 1,3-butadiene can be 1:1.

[0023] According to some preferred aspects of the present invention, the metal chelate ionic liquid represented by formula (I) is prepared by reacting a compound represented by formula (II) with a compound represented by formula (III) in a first solvent:

[0024]

[0025] a, b, c, and d are defined as above.

[0026] According to some preferred and specific aspects of the present invention, the first solvent comprises acetone. In some embodiments of the present invention, the first solvent is acetone.

[0027] According to some preferred and specific aspects of the present invention, the reaction of the compound represented by formula (II) and the compound represented by formula (III) is carried out at 10-40°C.

[0028] According to some preferred aspects of the present invention, the compound represented by formula (II) is synthesized using the following route:

[0029]

[0030] Among them, 2,6-dimethylaniline is reacted with 2,6-pyridinedicarbonyl chloride to generate a compound represented by formula (IV), and the compound represented by formula (IV) is reacted with copper chloride and methanol to generate a compound represented by formula (II).

[0031] According to some preferred aspects of the present invention, in the process of preparing the compound represented by formula (IV), the reaction is carried out in an alkaline environment, and the alkaline environment is formed by adding an alkaline reagent, and the alkaline reagent comprises triethylamine.

[0032] According to some preferred aspects of the present invention, in the process of preparing the compound represented by formula (IV), the reaction is carried out at 10-40° C. in a second solvent, wherein the second solvent contains a halogenated C1-C3 alkyl group. In some embodiments of the present invention, the halogen in the halogenated C1-C3 alkyl group is one or more selected from fluorine, chlorine and bromine, and further, the halogenated C1-C3 alkyl group can be dichloromethane, dichloroethane, etc.

[0033] According to some preferred aspects of the present invention, in the process of preparing the compound represented by formula (II), the reaction of the compound represented by formula (IV) with copper chloride and methanol is carried out at 10-40°C in the presence of an alkali metal methoxide, wherein the alkali metal methoxide is a combination of one or more selected from sodium methoxide, potassium methoxide and lithium methoxide.

[0034] According to some preferred aspects of the present invention, the method for preparing o-methylbenzoquinone comprises:

[0035] The o-cresol and / or m-cresol are oxidized in the first catalytic system in the presence of a first oxidant to generate o-methylbenzoquinone, and the reaction formula is:

[0036]

[0037] Wherein, the first oxidant is oxygen;

[0038] The first catalytic system comprises 4-R-2,2,6,6-tetramethylpiperidinyl oxide represented by formula (V), nitrite, protonic acid and a third solvent, wherein the third solvent is a combination of one or more selected from methanol, ethanol, propanol, tert-butanol, water and acetonitrile;

[0039] R is -H, -OH, -NHAc, -COOH, -COOPh or In the present invention, under the action of the catalytic system of the present invention, the target product can be obtained in high yield, especially oxygen can be used as an oxidant, and no catalyst such as transition metal is needed, which is low-cost and green and environmentally friendly; the present invention finds that only under the synergistic action of nitrite and protonic acid, in the above-mentioned specific solvents such as methanol, ethanol, propanol or acetonitrile solvents, can a good yield be obtained. At the same time, the present invention uses an organic catalyst 4-R-2,2,6,6-tetramethylpiperidinyl oxide (4-R-TEMPO) under the condition of no metal catalyst to realize the oxygen oxidation of o-cresol and / or m-cresol to o-methylbenzoquinone, which can avoid the use of halogens and transition metals, and is beneficial to industrial production and quality improvement of vitamin K3 drugs.

[0040] According to some preferred and specific aspects of the present invention, during the oxidation reaction, the first oxidant is provided by introducing pure oxygen gas or a gas mixture containing oxygen (such as air) into the reaction system. According to the present invention, the purity of oxygen in the pure oxygen gas is greater than 99%, and the oxygen concentration in the gas mixture containing oxygen is less than 99%.

[0041] According to some preferred aspects of the present invention, the reaction temperature of the oxidation reaction is 20-80°C.

[0042] According to some preferred aspects of the present invention, the reaction pressure of the oxidation reaction is 0.1-20 MPa.

[0043] According to some preferred aspects of the present invention, the molar ratio of the o-cresol and / or m-cresol, the 4-R-2,2,6,6-tetramethylpiperidinyl oxide represented by formula (V), the nitrite and the protonic acid is 10-200:1:1-4:1-4.

[0044] According to some preferred aspects of the present invention, the molar ratio of the total amount of 4-R-2,2,6,6-tetramethylpiperidinyl oxide represented by formula (V), the nitrite and the protonic acid to the o-cresol and / or m-cresol is 0.01-1:1.

[0045] According to some preferred aspects of the present invention, the protonic acid is a combination of one or more selected from trifluoromethanesulfonic acid, methanesulfonic acid, sulfuric acid, p-toluenesulfonic acid and hydrochloric acid alcohol solution. In some embodiments of the present invention, the hydrochloric acid alcohol solution can be added in the form of adding hydrochloric acid-ethanol solution.

[0046] More preferably, the protonic acid is trifluoromethanesulfonic acid and / or methanesulfonic acid.

[0047] According to some preferred aspects of the present invention, the nitrite is potassium nitrite and / or sodium nitrite.

[0048] According to some preferred aspects of the present invention, in the step of preparing o-methylbenzoquinone, R is -H, -OH, -NHAc, -COOH, -COOPh or The proton acid is at least one of trifluoromethanesulfonic acid and methanesulfonic acid, the third solvent is at least one of methanol, tert-butanol and acetonitrile, and the molar ratio of the o-cresol and / or m-cresol, the 4-R-2,2,6,6-tetramethylpiperidinoxide represented by formula (II), the nitrite and the proton acid is 10-50:1:1.5-2.5:1.5-2.5.

[0049] Another technical solution provided by the present invention is a method for preparing 2-methyl-1,4-naphthoquinone, which comprises the step of preparing 2-methyl-1,4-naphthoquinone using 2-methyl-1,4-tetrahydronaphthoquinone as a substrate, and also comprises the preparation of 2-methyl-1,4-tetrahydronaphthoquinone, wherein the preparation of the 2-methyl-1,4-tetrahydronaphthoquinone adopts the above-mentioned method for preparing 2-methyl-1,4-tetrahydronaphthoquinone.

[0050] Furthermore, the step of preparing 2-methyl-1,4-naphthoquinone using 2-methyl-1,4-tetrahydronaphthoquinone as a substrate can adopt a conventional method in the prior art.

[0051] Preferably, the step of preparing 2-methyl-1,4-naphthoquinone using 2-methyl-1,4-tetrahydronaphthoquinone as a substrate is carried out by the following process:

[0052] 2-methyl-1,4-tetrahydronaphthoquinone is subjected to an oxidative dehydrogenation reaction in the second catalytic system in the presence of a second oxidant to generate 2-methyl-1,4-naphthoquinone, and the reaction formula is:

[0053] in:

[0054] The second catalytic system comprises a heterogeneous nitrogen-doped carbon material supported cobalt catalyst and a fourth solvent;

[0055] The preparation method of the heterogeneous nitrogen-doped carbon material loaded with cobalt catalyst comprises: preparing glucosamine hydrochloride (molecular formula: C6H 13NO5·HCl, molecular weight 215.63), melamine and cobalt acetate are mixed and sintered under an inert atmosphere; wherein the mass ratio of the glucosamine hydrochloride to the melamine is 1:25-45, and the molar ratio of the glucosamine hydrochloride to the cobalt acetate is 1:0.01-0.75. In the present invention, a specific catalytic system, especially a heterogeneous nitrogen-doped carbon material-supported cobalt catalyst prepared by the method of the present invention, can realize the efficient and highly selective preparation of 2-methyl-1,4-naphthoquinone by oxidative dehydrogenation of 2-methyl-1,4-tetrahydronaphthoquinone. The process has good environmental protection, and the catalyst is easy to recycle and reuse, which is conducive to reducing costs.

[0056] According to the present invention, in the heterogeneous nitrogen-doped carbon material-supported cobalt catalyst prepared by the method of the present invention, the nitrogen-doped carbon material is used as a carrier, and the cobalt element obtained by sintering is coated by the carrier nitrogen-doped carbon material as an active component.

[0057] In some embodiments of the present invention, the inert atmosphere can be formed by introducing nitrogen, argon, etc.

[0058] According to some preferred aspects of the present invention, the mass ratio of the glucosamine hydrochloride to the melamine is 1:30-40. Further, the mass ratio of the glucosamine hydrochloride to the melamine is 1:32-38.

[0059] According to some preferred aspects of the present invention, the molar ratio of the glucosamine hydrochloride to the cobalt acetate is 1:0.02-0.70. Further, the molar ratio of the glucosamine hydrochloride to the cobalt acetate is 1:0.025-0.45.

[0060] In some preferred embodiments of the present invention, the molar ratio of the glucosamine hydrochloride to the cobalt acetate is 1:0.1-0.2.

[0061] According to some preferred aspects of the present invention, the sintering is performed at 550-850°C.

[0062] Furthermore, the sintering is carried out in the following manner: sintering at 550-650°C for a sintering time of t1; then heating to 750-850°C at a heating rate of 1.5-3.5°C / min and sintering for a sintering time of t2, t1 and t2 being 0.5-2h respectively.

[0063] In some preferred embodiments of the present invention, the implementation method of preparing the heterogeneous nitrogen-doped carbon material-loaded cobalt catalyst includes: dispersing glucosamine hydrochloride, melamine and cobalt acetate in deionized water, stirring under heating conditions until the deionized water is completely evaporated, and then sintering the dried mixture under an inert atmosphere to prepare the heterogeneous nitrogen-doped carbon material-loaded cobalt catalyst.

[0064] According to some preferred aspects of the present invention, the added mass of the heterogeneous nitrogen-doped carbon material-supported cobalt catalyst is greater than 0.1% of the added mass of the 2-methyl-1,4-tetrahydronaphthoquinone, in terms of mass percentage.

[0065] Further, in terms of mass percentage, the added mass of the heterogeneous nitrogen-doped carbon material-supported cobalt catalyst is 0.5%-10% of the added mass of the 2-methyl-1,4-tetrahydronaphthoquinone. Further, in terms of mass percentage, the added mass of the heterogeneous nitrogen-doped carbon material-supported cobalt catalyst is 0.5%-6% of the added mass of the 2-methyl-1,4-tetrahydronaphthoquinone. Further, in terms of mass percentage, the added mass of the heterogeneous nitrogen-doped carbon material-supported cobalt catalyst is 0.8%-5% of the added mass of the 2-methyl-1,4-tetrahydronaphthoquinone.

[0066] According to the present invention, under the second catalytic system of the present invention, the oxidative dehydrogenation reaction can be carried out at a relatively low temperature. According to some preferred and specific aspects of the present invention, the reaction temperature of the oxidative dehydrogenation reaction is 0-40°C.

[0067] In some embodiments of the present invention, the reaction time of the oxidative dehydrogenation reaction is 0.5-5h.

[0068] According to some preferred aspects of the present invention, the fourth solvent is an alcohol solvent and / or a nitrile solvent

[0069] According to some preferred aspects of the present invention, the alcohol solvent is a C1-C6 alkyl alcohol. In the present invention, "C1-C6 alkyl alcohol" is an alkyl alcohol having 1, 2, 3, 4, 5 or 6 carbon atoms.

[0070] Furthermore, the alcohol solvent is a combination of one or more selected from methanol, ethanol, propanol, isopropanol, n-butanol, isobutanol, n-pentanol and isopentanol.

[0071] According to some preferred aspects of the present invention, the nitrile solvent comprises acetonitrile.

[0072] According to the present invention, in the step of preparing 2-methyl-1,4-naphthoquinone using 2-methyl-1,4-tetrahydronaphthoquinone as a raw material under the second catalytic system of the present invention, the second oxidant can be oxygen, which is green and environmentally friendly, and can be provided by passing pure oxygen gas or a gas mixture containing oxygen (such as air) into the reaction system. According to the present invention, the purity of oxygen in the pure oxygen gas is greater than 99%, and the oxygen concentration in the gas mixture containing oxygen is less than 99%. Furthermore, the second oxidant can be provided by passing pure oxygen gas greater than 99% or air into the reaction system.

[0073] In some preferred embodiments of the present invention, the oxidative dehydrogenation reaction is carried out as follows: 2-methyl-1,4-tetrahydronaphthoquinone, a heterogeneous nitrogen-doped carbon material-loaded cobalt catalyst, and a solvent are uniformly mixed, and then pure oxygen gas or air with a purity greater than 99% is introduced, and the reaction temperature is controlled to be 0-40°C and the reaction pressure is controlled to be 0.01-0.15MPa to carry out an oxidative dehydrogenation reaction to generate 2-methyl-1,4-naphthoquinone.

[0074] In the present invention, the cobalt acetate may contain crystal water or may be treated to not contain crystal water.

[0075] In the present invention, the descriptions of "first", "second", "third" and "fourth" are only for distinguishing the catalytic systems or solvents used in each reaction, which is convenient for description and not easy to confuse. They do not represent a sequence relationship, nor do they mean the same or different.

[0076] Due to the application of the above technical solution, the present invention has the following advantages compared with the prior art:

[0077] The inventors of the present invention accidentally discovered during the experiment that the use of a metal chelated ionic liquid represented by formula (I) as a Lewis acid to catalyze the Diels-Alder reaction of o-methylbenzoquinone and 1,3-butadiene has a significant effect and can obtain 2-methyl-1,4-tetrahydronaphthoquinone quickly, efficiently and highly selectively.

[0078] In addition, the metal chelate ionic liquid not only has good thermal stability, but also has very good solubility in conventional organic solvents and water, so the catalyst can be recycled by distillation or by water washing and separation. BRIEF DESCRIPTION OF THE DRAWINGS

[0079] Figure 1 The electrospray ionization high-resolution mass spectrum and atomic absorption characterization spectrum of the cations in the copper chelate ionic liquid Chelate-Cu-IL prepared in Example 1 of the present invention;

[0080] Figure 2The electrospray ionization high-resolution mass spectrum and atomic absorption characterization spectrum of the anions in the copper chelate ionic liquid Chelate-Cu-IL prepared in Example 1 of the present invention;

[0081] Figure 3 : is the X-ray diffraction spectrum of Co@CN catalysts with different cobalt contents. Example 26 uses 1Co@CN catalyst, Example 33 uses 0.25Co@CN, Example 35 uses 2Co@CN, and Example 36 uses 4Co@CN catalyst;

[0082] Figure 4 This is the X-ray photoelectron spectrum of the 1Co@CN catalyst and CN in Example 26 of the present invention (oxygen 1s electron);

[0083] Figure 5 is the X-ray photoelectron spectrum of the 1Co@CN catalyst and CN in Example 26 of the present invention (nitrogen 1s electron);

[0084] Figure 6 X-ray photoelectron energy spectra of 1Co@CN catalyst at different binding energies in Example 26 of the present invention (cobalt 2p electrons);

[0085] Figure 7 1Co@CN catalyst of Example 26 and Co / AC catalyst of Comparative Example 16 in the examples of the present invention are X-ray diffraction spectra. DETAILED DESCRIPTION

[0086] The above scheme is further described below in conjunction with specific embodiments; it should be understood that these embodiments are used to illustrate the basic principles, main features and advantages of the present invention, and the present invention is not limited to the scope of the following embodiments; the implementation conditions adopted in the embodiments can be further adjusted according to specific requirements, and the implementation conditions not specified are usually the conditions in conventional experiments.

[0087] Unless otherwise specified in the following examples, all raw materials are commercially available or prepared by conventional methods in the art.

[0088] In the following, all reaction conversions and yields were determined by gas chromatography (using commercially available starting materials and products as standard curves).

[0089] In the following, the structural formula of 4-OH-TEMPO is: The structural formula of 4-COOH-2,2,6,6-tetramethylpiperidinyl oxide is: The structural formula of 4-COOPh-2,2,6,6-tetramethylpiperidinoxide is: The structural formula of 4-NHAc-2,2,6,6-tetramethylpiperidinyl oxide is: The structural formula of 2,2,6,6-tetramethylpiperidinyl oxide is: The structural formula of 4-Maleimide (maleimide)-2,2,6,6-tetramethylpiperidinoxide is: The structural formula of 4-NH2-2,2,6,6-tetramethylpiperidinoxide is:

[0090] In the following, trifluoromethanesulfonic acid, p-toluenesulfonic acid and methanesulfonic acid are respectively commercially available products with a purity of 99%; acetic acid is commercially available products with a purity of 99.5%; nitric acid is 98% fuming nitric acid, an analytically pure reagent; sulfuric acid is commercially available products with a purity of AR (Shanghai test), 95.0-98.0%; hydrogen chloride is commercially available hydrogen chloride-ethanol solution, and the concentration of hydrogen chloride is 2 mol / L; the feeding amount of each acid is converted according to the required molar amount.

[0091] Example 1

[0092] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate), which adopts the following synthetic route:

[0093]

[0094] The method comprises the following steps:

[0095] (1) Preparation of o-methylbenzoquinone

[0096] 1mmol o-cresol, 0.05mmol 4-OH-TEMPO, 0.1mmol sodium nitrite, 0.1mmol trifluoromethanesulfonic acid and 2mL methanol were added to a 20mL reaction bottle, a magnet was added, oxygen (pure oxygen gas with a purity greater than 99%) was passed, the pressure was 0.5MPa, and the reaction was carried out at 30°C and 800rpm for 18 hours. The reaction conversion rate was 100%, and the yield of o-methylbenzoquinone was 92.7%. The reaction solution was vortexed to remove the solvent and dissolved in 10mL ethyl acetate, washed twice with 2mL sodium hydroxide aqueous solution, extracted 3 times with 5mL saturated brine, and the organic phase was dried over anhydrous sodium sulfate and then vortexed to obtain purified o-methylbenzoquinone with a purity of 99%.

[0097] (2) Preparation of 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate)

[0098] 0.2 mmol Chelate-Cu-IL (catalyst), 2 mmol o-methylbenzoquinone prepared according to the method of step (1) above and 2 mmol 1,3-butadiene were added to a 20 mL reaction bottle, and the mixture was reacted at 70° C. for 8 hours. The reaction conversion rate was 100%, and the yield of 2-methyl-1,4-tetrahydronaphthoquinone was 95.1%. The reaction solution was vortexed to remove the solvent and dissolved in 10 mL ethyl acetate. The reaction solution was washed with 5 mL saturated brine for 3 times. The organic phase was dried over anhydrous sodium sulfate and then vortexed to obtain purified 2-methyl-1,4-tetrahydronaphthoquinone with a purity of 98%.

[0099] Among them, the copper chelate ionic liquid Chelate-Cu-IL (Formula (I)) is prepared by the following method:

[0100] The reaction formula is as follows:

[0101]

[0102] Specifically: 2,6-dimethylaniline (10 mmol) and triethylamine (26 mmol) were added to a 250 mL round-bottom flask, and a mixture of 2,6-pyridinedicarbonyl chloride (5 mmol) and dichloromethane (20 mL) was slowly added dropwise to the flask at 0°C; after stirring at room temperature for 24 h, the solvent was filtered out, and the filter cake was washed with distilled water and ether for 3-5 times, and vacuum dried at 40°C to obtain a white powder ligand (the compound shown in formula (IV)). The ligand (2.0 mmol), anhydrous copper chloride (2.0 mmol) and MeOH (100 mL) were added to a 250 mL round-bottom flask, and a 0.5 M NaOMe methanol solution (8.0 mL) was added to the mixture; the reaction was stirred at room temperature for 24 h, and an oily solid was obtained by rotary evaporation at 40 °C; the solid was dissolved in acetonitrile (20 mL), and toluene (100 mL) was added and allowed to stand for 30 min before filtering. The filtrate was vacuum rotary evaporated at 40 °C to obtain a green powder (the compound shown in formula (II)), which was vacuum dried overnight. Add 2 mmol of green powder (compound represented by formula (II)) and trihexyl (tetradecyl) phosphine chloride (compound represented by formula (III-1)) to a 50 mL round-bottom flask, add 10 mL of acetone, stir at room temperature for 12 h, and rotary evaporate to obtain a green liquid, which is then extracted with dichloromethane (3*5 mL). The lower organic phase is again vacuum rotary evaporated at 40°C to remove the solvent, and then vacuum dried for 24 h to obtain the product: copper chelate ionic liquid Chelate-Cu-IL (formula (I));

[0103] The elemental analysis table of copper chelate ionic liquid Chelate-Cu-IL (Formula (I)) is shown in Table 1:

[0104] Table 1

[0105]

[0106] The electrospray ionization high-resolution mass spectrum and atomic absorption characterization spectrum are shown in Figure 1 and Figure 2 shown.

[0107] Example 2

[0108] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that in step (2), the catalyst is 0.0004 mmol Chelate-Cu-IL, the reaction temperature is 80°C, and the rest is exactly the same as Example 1. The reaction conversion rate is 92.2%, the yield of 2-methyl-1,4-tetrahydronaphthoquinone is 81.5%, and the purity is 91%.

[0109] Example 3

[0110] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that in step (2), the catalyst is 0.002 mmol Chelate-Cu-IL, the reaction temperature is 40°C, and the rest is exactly the same as Example 1. The reaction conversion rate is 100%, the yield of 2-methyl-1,4-tetrahydronaphthoquinone is 92.5%, and the purity is 97%.

[0111] Example 4

[0112] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that in step (2), the catalyst is 0.04 mmol Chelate-Cu-IL, the reaction temperature is 0°C, and the rest is exactly the same as Example 1. The reaction conversion rate is 90.9%, the yield of 2-methyl-1,4-tetrahydronaphthoquinone is 89.4%, and the purity is 95%.

[0113] Comparative Example 1

[0114] Compared with Example 1, Comparative Example 1 differs in that, in step (2), the copper chelate ionic liquid Chelate-Cu-IL is replaced by "Chelate-Cu-MeOH", and the rest is exactly the same as Example 1, the reaction conversion rate is 63.5%, the yield of 2-methyl-1,4-tetrahydronaphthoquinone is 55.7%, and the purity is 82%.

[0115]

[0116] Comparative Example 2

[0117] Compared with Example 1, Comparative Example 2 differs in that, in step (2), no copper chelate ionic liquid Chelate-Cu-IL is added, and the rest is exactly the same as Example 1. The reaction conversion rate is 36.9%, the yield of o-methylbenzoquinone is 30.1%, and the purity is 76%.

[0118] Example 5

[0119] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the substrate in step (1) is 1 mmol of m-cresol, and the rest is exactly the same as Example 1. The reaction conversion rate is 98.2%, the yield of o-methylbenzoquinone is 87.9%, and the purity is 97%.

[0120] Example 6

[0121] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.005 mmol 4-NHAc-2,2,6,6-tetramethylpiperidinoxide, the protonic acid is 0.01 mmol trifluoromethanesulfonic acid, 0.01 mmol NaNO2, and the rest is exactly the same as Example 1. The reaction conversion rate is 89.4%, the yield of o-methylbenzoquinone is 80.1%, and the purity is 95%.

[0122] Example 7

[0123] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.1 mmol 4-NHAc-2,2,6,6-tetramethylpiperidinoxide, the protonic acid is 0.2 mmol trifluoromethanesulfonic acid, and 0.2 mmol NaNO2. The rest is exactly the same as Example 1. The reaction conversion rate is 100%, the yield of o-methylbenzoquinone is 92.4%, and the purity is 98%.

[0124] Example 8

[0125] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 13, this example differs in that air is passed through step (1), and the rest is exactly the same as Example 13. The reaction conversion rate is 100%, the yield of o-methylbenzoquinone is 86.4%, and the purity is 97%.

[0126] Example 9

[0127] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the solvent in step (1) is 2 mL of acetonitrile, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 89.2%, and the purity is 97%.

[0128] Example 10

[0129] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, this example is different in that the solvent methanol is adjusted to 2 mL of tert-butanol in step (1), and the rest is exactly the same as Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 92.3%, and the purity is 97%.

[0130] Embodiment 11

[0131] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, this example differs in that in step (1), the solvent methanol is adjusted to 1.6 mL of tert-butanol plus 0.4 mL of acetonitrile, and the rest is exactly the same as Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 94.3%, and the purity is 98%.

[0132] Example 12

[0133] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.05 mmol 4-COOH-2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 88.5%, and the purity is 95%.

[0134] Embodiment 13

[0135] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.05 mmol 4-NHAc-2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 89.7%, and the purity is 97%.

[0136] Embodiment 14

[0137] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.05 mmol 2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 90.6%, and the purity is 98%.

[0138] Embodiment 15

[0139] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that:

[0140] The catalyst in step (1) is 0.05 mmol 4-Maleimide-2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as in Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 91.6%, and the purity is 99%.

[0141] Example 16

[0142] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the catalyst in step (1) is 0.05 mmol 4-COOPh-2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as Example 13. The conversion rate is 100%, the yield of o-methylbenzoquinone is 89.9%, and the purity is 97%.

[0143] Embodiment 17

[0144] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, this example is different in that the proton acid in step (1) is 0.1 mmol methanesulfonic acid, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 93.1%, and the purity is 99%.

[0145] Embodiment 18

[0146] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the proton acid in step (1) is 0.1 mmol H2SO4, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 81.4%, and the purity is 95%.

[0147] Embodiment 19

[0148] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, this example is different in that the protonic acid in step (1) is 0.1 mmol HCl, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 79.4%, and the purity is 96%.

[0149] Embodiment 20

[0150] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the proton acid in step (1) is 0.1 mmol p-toluenesulfonic acid, and the rest is exactly the same as Example 1. The conversion rate is 89.2%, the yield of o-methylbenzoquinone is 74.1%, and the purity is 98%.

[0151] Embodiment 21

[0152] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that in step (1), the amount of trifluoromethanesulfonic acid is 0.2 mmol, the amount of NaNO2 is 0.2 mmol, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 84.9%, and the purity is 96%.

[0153] Embodiment 22

[0154] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that in step (1), the amount of trifluoromethanesulfonic acid is 0.05 mmol, the amount of NaNO2 is 0.05 mmol, and the rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 79.5%, and the purity is 93%.

[0155] Embodiment 23

[0156] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the reaction temperature in step (1) is 20°C and the pressure is 20 MPa. The rest is exactly the same as Example 1. The conversion rate is 95.4%, the yield of o-methylbenzoquinone is 84.6%, and the purity is 96%.

[0157] Embodiment 24

[0158] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the reaction temperature in step (1) is 80° C. and the pressure is 0.1 MPa. The rest is exactly the same as Example 1. The conversion rate is 93.1%, the yield of o-methylbenzoquinone is 83.3%, and the purity is 94%.

[0159] Embodiment 25

[0160] This example provides a method for preparing 2-methyl-1,4-tetrahydronaphthoquinone (vitamin K3 intermediate). Compared with Example 1, the difference between this example and Example 1 is that the reaction temperature in step (1) is 40°C and the pressure is 10 MPa. The rest is exactly the same as Example 1. The conversion rate is 100%, the yield of o-methylbenzoquinone is 90.4%, and the purity is 97%.

[0161] Comparative Example 3

[0162] Compared with Example 1, this example differs in that the catalyst in step (1) is 0.05 mmol 4-NH2-2,2,6,6-tetramethylpiperidinoxide, and the rest is exactly the same as Example 1, with a conversion rate of 80.9%, an o-methylbenzoquinone yield of 69.3%, and a purity of 86%.

[0163] Comparative Example 4

[0164] Compared with Example 1, this example differs in that in step (1), trifluoromethanesulfonic acid is replaced by 0.1 mmol acetic acid, and the rest is exactly the same as Example 1. The conversion rate is 50.9%, the yield of o-methylbenzoquinone is 41.4%, and the purity is 90%.

[0165] Comparative Example 5

[0166] Compared with Example 1, this example differs in that in step (1), trifluoromethanesulfonic acid is replaced by 0.1 mmol nitric acid, and the rest is exactly the same as Example 1. The conversion rate is 85.4%, the yield of o-methylbenzoquinone is 50.2%, and the purity is 86%.

[0167] Comparative Example 6

[0168] The difference between this example and Example 1 is that no trifluoromethanesulfonic acid is added during the reaction in step (1). The rest is exactly the same as Example 1. The reaction conversion rate is 13.1% and the yield of o-methylbenzoquinone is 12.1%.

[0169] Comparative Examples 4-6 show that trifluoromethanesulfonic acid, methanesulfonic acid, p-toluenesulfonic acid and other proton acids are the key to the disproportionate TEMPO catalyst, which plays a key role in the catalytic effect and is one of the key factors in obtaining a high yield.

[0170] Comparative Example 7

[0171] Compared with Example 1, this example differs in that in step (1), the solvent 2 mL of methanol is replaced by 2 mL of dimethyl sulfoxide (DMSO), and the rest is exactly the same as Example 1. The reaction conversion rate is 20.8%, and the yield of o-methylbenzoquinone is 2.1%.

[0172] Comparative Example 8

[0173] Compared with Example 1, this example differs in that in step (1), the solvent 2 mL of methanol is replaced by 2 mL of dichloromethane. The rest is exactly the same as Example 1. The reaction conversion rate is 96.4%, and the yield of o-methylbenzoquinone is 34.3%.

[0174] Comparative Example 9

[0175] The difference between this example and Example 1 is that in step (1), the solvent 2 mL of methanol is replaced by 2 mL of chlorobenzene. The rest is exactly the same as Example 1. The reaction conversion rate is 100%, and the yield of o-methylbenzoquinone is 23.1%.

[0176] Comparative Examples 7-9 illustrate that the specific solvent system of the present invention plays a decisive role in the yield of o-methylbenzoquinone.

[0177] Comparative Example 10

[0178] Compared with Example 1, the difference between this example and Example 1 is that no TEMPO catalyst is added during the reaction in step (1), and the rest is exactly the same as Example 1, the reaction conversion rate is 0%, and the yield of o-methylbenzoquinone is 0%. This comparative example shows that TEMPO catalyst plays a key role in activating o-cresol and converting it into o-methylbenzoquinone.

[0179] Comparative Example 11

[0180] Compared with Example 1, the difference between this example and Example 1 is that NaNO2 is not added in step (1), and the rest is exactly the same as Example 1. The reaction conversion rate is 8.4%, and the yield of o-methylbenzoquinone is 7.1%. This comparative example shows that nitrite acts as a circulating TEMPO catalyst, thereby completely converting the substrate.

[0181] In the following, the preparation method of the heterogeneous nitrogen-doped carbon material supported cobalt catalyst yCo@CN is as follows: 2g GAH, 70g melamine and y mmol cobalt acetate (since the raw material cobalt acetate is easily deliquescent and carries water, the cobalt acetate can be added in the form of a hydrate, usually tetrahydrated cobalt acetate, or it can be added after dehydration, and only the molar addition amount of cobalt acetate needs to be controlled) is dissolved in deionized water, and then stirred at 80°C to evaporate the solution. The dried solid is transferred to a tube furnace and calcined in nitrogen at 590°C for 1 hour, then heated to 790°C at a heating rate of 2.5°C / min, and maintained at 790°C for 50 minutes, with a nitrogen flow rate of 400mL / min, and cooled naturally to obtain a catalyst, which is recorded as yCo@CN.

[0182] Embodiment 26

[0183] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3), which adopts the following synthetic route:

[0184]

[0185] The method comprises the following steps:

[0186] (i) Preparation of 2-methyl-1,4-tetrahydronaphthoquinone according to the method of Example 1

[0187] (ii) Preparation of 2-methyl-1,4-naphthoquinone (vitamin K3)

[0188] The method comprises the following steps: adding 3mmol 2-methyl-1,4-tetrahydronaphthoquinone, 0.01g 1Co@CN, 4.0g methanol, adding a magnet, connecting an oxygen bag (0.1MPa, pure oxygen gas with a purity greater than 99%), ventilating 3 times, reacting at 25°C for 1 hour, filtering and recovering the catalyst, washing the catalyst 3 times with a solvent, combining the mother liquor for upper tower distillation, and obtaining a pure product. The reaction conversion rate is 99.3%, the vitamin K3 yield is 98.1%, and the purity is 98.7%;

[0189] Among them, the preparation of 1Co@CN catalyst: a mixture of 2g GAH, 70g melamine and 1mmol cobalt acetate was dissolved in deionized water, and then stirred at 80°C to evaporate the solution. The dried solid was transferred to a tube furnace and calcined at 590°C in a nitrogen atmosphere for 1 hour, and then heated to 790°C at a heating rate of 2.5°C / min and maintained at 790°C for 50 minutes with a nitrogen flow rate of 400mL / min. The catalyst was naturally cooled to obtain a catalyst, which was denoted as 1Co@CN. Its X-ray diffraction spectrum (XRD) and X-ray photoelectron spectroscopy (XPS) are shown in Figure 3-Figure 6 .

[0190] Embodiment 27

[0191] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the catalyst is 0.004g 1Co@CN, and the rest is exactly the same as Example 26. The reaction conversion rate is 92.8%, the vitamin K3 yield is 89.4%, and the purity is 96.1%.

[0192] Embodiment 28

[0193] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the catalyst is 0.02g 1Co@CN, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 98.7%, and the purity is 99.3%.

[0194] Embodiment 29

[0195] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the catalyst is 0.005g 1Co@CN, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 94.2%, and the purity is 98.9%.

[0196] Embodiment 30

[0197] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, this example differs in that the solvent methanol is replaced by propanol, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 96.4%, and the purity is 99%.

[0198] Embodiment 31

[0199] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, this example differs in that the reaction temperature is adjusted from 25°C to 0°C, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 91.1%, and the purity is 96.8%.

[0200] Embodiment 32

[0201] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, this example differs in that the reaction temperature is adjusted from 25°C to 40°C, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 92.6%, and the purity is 98.7%.

[0202] Embodiment 33

[0203] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the amount of cobalt acetate added during the preparation of the catalyst is 0.25 mmol, the prepared catalyst is recorded as 0.25Co@CN, and the X-ray diffraction spectrum (XRD) is shown in Figure 3 , the rest is exactly the same as Example 26, the reaction conversion rate is 92.2%, the vitamin K3 yield is 90.6%, and the purity is 97.7%.

[0204] Embodiment 34

[0205] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the amount of cobalt acetate added during the preparation of the catalyst is 1.5 mmol, and the rest is exactly the same as Example 26. The reaction conversion rate is 100%, the vitamin K3 yield is 98.9%, and the purity is 99%.

[0206] Embodiment 35

[0207] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, this example differs in that the amount of cobalt acetate added during the preparation of the catalyst is 2 mmol, the prepared catalyst is denoted as 2Co@CN, and the X-ray diffraction spectrum (XRD) is shown in Figure 3 , the rest is exactly the same as Example 26, the reaction conversion rate is 96.3%, the vitamin K3 yield is 92.7%, and the purity is 97.8%.

[0208] Embodiment 36

[0209] This example provides a method for preparing 2-methyl-1,4-naphthoquinone (vitamin K3). Compared with Example 26, the difference between this example and Example 26 is that the amount of cobalt acetate added during the preparation of the catalyst is 4 mmol, the catalyst is recorded as 4Co@CN, and the X-ray diffraction spectrum (XRD) is shown in Figure 3 , the rest is exactly the same as Example 26, the reaction conversion rate is 94%, the vitamin K3 yield is 91.3%, and the purity is 97.5%.

[0210] Example 37 Catalyst recovery and application experiment

[0211] Recycling and applying the catalyst, we conducted an amplification experiment on the oxidation reaction of 2-methyl-1,4-tetrahydronaphthoquinone. The specific steps are as follows: in a 100mL reaction bottle, add 30mmol 2-methyl-1,4-tetrahydronaphthoquinone, 0.1g 1Co@CN, 40g methanol, add a magnet, connect an oxygen bag (0.1MPa, pure oxygen gas with a purity greater than 99%), ventilate 3 times, react at 25°C for 1 hour, filter and recover the catalyst, wash the catalyst 3 times with a solvent, combine the mother liquor for upper tower distillation, and obtain a pure product. The reaction conversion rate is 100%, the vitamin K3 yield is 98.5%, and the purity is 99%, indicating that a 10-fold amplification has no significant effect on the yield and product purity.

[0212] Catalyst Co@CN recovery method: filter the reaction liquid to separate the Co@CN catalyst, soak the Co@CN catalyst with appropriate amounts of acetone and methanol three times, filter it, and then put it in a vacuum drying oven at 60°C for 8 hours before applying it.

[0213] Furthermore, compared with Example 26, the difference is that the 1Co@CN catalyst used is a recycled catalyst, and the rest is exactly the same as Example 26, with a reaction conversion rate of 99.0%, a vitamin K3 yield of 97.2%, and a purity of 99.1%. The yield did not decrease significantly, which shows that the 1Co@CN catalyst has good stability. In addition, the application experiment was carried out again, and the reaction conversion rate was 98.4%, the vitamin K3 yield was 96.3%, and the purity was 98.1%. The conversion rate and yield were slightly reduced, which may be caused by the reduction of the catalyst mass due to the filtering and washing operation during the recovery process.

[0214] Comparative Example 12

[0215] Compared with Example 26, this example differs in that the amount of cobalt acetate added during the catalyst preparation process is 9 mmol, and the rest is exactly the same as Example 26. The reaction conversion rate is 85.8%, the vitamin K3 yield is 90.7%, and the purity is 97.4%.

[0216] Comparative Example 13

[0217] Compared with Example 26, the difference between this example is that cobalt nitrate (with 6 crystal waters, i.e., hexahydrated cobalt nitrate) is used instead of cobalt acetate in the preparation process of 1Co@CN, and the amount of cobalt nitrate hexahydrate added is 1 mmol. The rest is exactly the same as Example 26, and the reaction conversion rate is 62.1%, the vitamin K3 yield is 54.1%, and the purity is 83.6%. This shows that different cobalt salts have a greater impact on catalytic performance.

[0218] Comparative Example 14

[0219] Compared with Example 26, this example differs in that the catalyst is replaced by Co3O4, and the rest is exactly the same as Example 26, the reaction conversion rate is 0%, and the vitamin K3 yield is 0%. This comparative example shows that Co@CN plays a key role in activating the substrate and cannot be replaced by Co3O4.

[0220] Comparative Example 15

[0221] Compared with Example 26, this example differs in that the catalyst is replaced with Co2O3, and the rest is exactly the same as Example 26, with a reaction conversion rate of 0% and a vitamin K3 yield of 0%. This comparative example further illustrates that Co@CN plays a key role in activating the substrate and cannot be replaced by common cobalt oxides.

[0222] Comparative Example 16

[0223] Compared with Example 26, this example differs in that the catalyst Co / AC supported on activated carbon is used instead of 1Co@CN, and the rest is exactly the same as Example 26;

[0224] Among them, the catalyst Co / AC supported on activated carbon is prepared by the following method: 2.11g of cobalt acetate tetrahydrate is weighed, and an appropriate amount of ethanol and water are added to dissolve it, and then 10g of activated carbon is added, mixed evenly, and left to stand for 8 hours, and then the solvent is evaporated by stirring with a glass rod in a water bath at 80°C, and then dried in a drying oven at 100°C overnight. Take it out, grind it evenly with a mortar, and then place it in a tube furnace in a nitrogen atmosphere at 550°C for 3 hours (heating rate 5°C / min), and cool it to room temperature in a nitrogen atmosphere to obtain a Co / AC catalyst.

[0225] Comparison of XRD patterns of Co / AC and 1Co@CN catalysts ( Figure 7 ), although the cobalt contents of the two are similar (the cobalt content is obtained by ICP detection), we can find that the XRD diffraction peak of the loaded Co / AC catalyst is sharper, indicating that the cobalt particles are larger, which may be due to metal agglomeration, while the XRD diffraction peak intensity of 1Co@CN is weaker, indicating that the metal has better dispersion.

[0226] The reaction conversion rate was 2%, and the vitamin K3 yield was 1.3%. By comparison, it can be seen that the performance of the 1Co@CN catalyst prepared by the method of the present invention is significantly better than that of the supported catalyst Co / AC.

[0227] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent changes or modifications made according to the spirit of the present invention should be included in the protection scope of the present invention.

[0228] The endpoints and any values ​​of the ranges disclosed in this article are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article.

Claims

1. A method for preparing 2-methyl-1,4-tetrahydronaphthoquinone, the method comprising: allowing o-methylbenzoquinone to undergo an addition reaction with 1,3-butadiene to generate 2-methyl-1,4-tetrahydronaphthoquinone, the reaction formula being: Features: The addition reaction is carried out under the catalytic action of the metal chelate ionic liquid represented by formula (I); a, b, c, and d are each independently 0, 1, or 2.

2. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 1, characterized in that: The values ​​of a, b, c, and d are the same.

3. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 1, characterized in that: The metal chelate ionic liquid represented by formula (I) is:

4. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 1, characterized in that: The molar ratio of the metal chelate ionic liquid represented by the formula (I) to the o-methylbenzoquinone is 1:5-5000.

5. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 4, characterized in that: The molar ratio of the metal chelate ionic liquid represented by the formula (I) to the o-methylbenzoquinone is 1:10-5000.

6. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 1, characterized in that: The reaction temperature of the addition reaction is 0-80° C.; and / or, the reaction pressure of the addition reaction is normal pressure; and / or, the feeding molar ratio of the o-methylbenzoquinone to the 1,3-butadiene is 1:0.95-1.

05.

7. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 1, characterized in that: The metal chelate ionic liquid represented by formula (I) is prepared by reacting a compound represented by formula (II) with a compound represented by formula (III) in a first solvent: ， a, b, c, d are defined as before.

8. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 7, characterized in that: The first solvent comprises acetone; and / or the reaction is carried out at 10-40°C.

9. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 7, characterized in that: The compound represented by formula (II) is synthesized by the following route: Among them, 2,6-dimethylaniline is reacted with 2,6-pyridinedicarbonyl chloride to generate a compound represented by formula (IV), and the compound represented by formula (IV) is reacted with copper chloride and methanol to generate a compound represented by formula (II).

10. The method for preparing 2-methyl-1,4-tetrahydronaphthoquinone according to claim 9, characterized in that: In the process of preparing the compound of formula (IV), the reaction is carried out in an alkaline environment, and the alkaline environment is formed by adding an alkaline reagent, and the alkaline reagent comprises triethylamine; and / or, in the process of preparing the compound of formula (IV), the reaction is carried out at 10-40°C in a second solvent, and the second solvent comprises a halogenated C1-C3 alkyl; and / or, in the process of preparing the compound of formula (II), the reaction of the compound of formula (IV) with copper chloride and methanol is carried out at 10-40°C in the presence of an alkali metal methoxide, and the alkali metal methoxide is a combination of one or more selected from sodium methoxide, potassium methoxide and lithium methoxide.

11. A method for preparing 2-methyl-1,4-naphthoquinone, the method comprising the step of preparing 2-methyl-1,4-naphthoquinone using 2-methyl-1,4-tetrahydronaphthoquinone as a substrate, characterized in that: The method also includes the preparation of 2-methyl-1,4-tetrahydronaphthoquinone, and the preparation of the 2-methyl-1,4-tetrahydronaphthoquinone adopts the preparation method described in any one of claims 1 to 10.

Images