A preparation method of 10,10-dimethylanthraquinone

Abstract

The present invention provides a method for preparing 10,10-dimethylanthraquinone, belonging to the field of drug synthesis. The preparation method includes adding 9,10-anthracene dione to an aprotic solvent, temperature-controlled dripping of a methyl metal organic compound under inert gas protection, temperature-controlled reaction after the dropwise addition is completed, and 10,10-dimethylanthraquinone is obtained by post-treatment. The present invention prepares 10,10-dimethylanthraquinone by 9,10-anthracene dione as a raw material, and the cost of the reaction route is about 30% of the cost of the existing preparation method, which greatly reduces the production cost of 10,10-dimethylanthraquinone; at the same time, the preparation method of 9,10-anthracene dione is mature, and there is sufficient supply to avoid the use of 2-benzylbenzoic acid methyl ester, which is expensive and in short supply; in addition, the preparation method of the present invention has a short reaction step, the raw materials used in the reaction are easy to obtain, and the three wastes generated after the reaction are less, which reduces the pollution to the environment and conforms to the concept of green chemistry.

Description

Technical Field

[0001] The invention relates to a method for preparing 10,10-dimethylanthraquinone, and belongs to the field of drug synthesis. Background Art

[0002] 10,10-dimethylanthraquinone is an important intermediate for the synthesis of bulk drugs (such as melitracen hydrochloride). The existing preparation method of 10,10-dimethylanthraquinone is usually prepared by a five-step method, that is, using 2-benzylbenzoic acid as a raw material, after methyl esterification reaction, reacting with a methyl Grignard reagent to generate (2-benzyl)-phenyl-2-isopropanol, and then cyclizing with sulfuric acid to synthesize 9,9-dimethyl-9,10-dihydroanthracene, and finally oxidizing under the action of chromium trioxide to prepare 10,10-dimethylanthraquinone-9-one.

[0003]

[0004] The above route has five chemical reactions, involving the use of zinc powder, Grignard reagent, concentrated sulfuric acid, and chromium trioxide. Each step will produce a lot of three wastes, especially the waste chromic acid produced in the last step, which has a great impact on the environment and does not conform to the concept of green chemistry. Subsequent technologies have optimized this method route by protecting the ketone carbonyl to avoid additional reduction and oxidation, but there are still defects in this synthetic route, such as more steps, long production cycle, low total yield, and the generation of a large amount of waste acid and heavy metal waste.

[0005] Some other existing technologies use phthalic anhydride as a raw material, synthesize 3,3-dimethyl-1-phenyl-1,3-dihydroisobenzofuran-1-ol through a two-step reaction of methylmagnesium bromide and phenylmagnesium bromide, and then prepare the target product 10,10-dimethylanthraquinone through a three-step reaction of sulfuric acid ring closure, such as Chinese patent CN109824493.

[0006]

[0007] This route uses two-step Grignard reaction, which has high requirements on reaction system conditions. Using concentrated sulfuric acid as solvent and catalyst for rearrangement will produce a large amount of waste acid that harms the environment. In addition, the total yield of the three-step reaction is only about 20%, and the conversion rate is extremely low.

[0008] Some existing technologies are to obtain o-chlorodiphenylmethane by substitution reaction of o-chlorobenzyl chloride with benzene, and then to react the o-chlorodiphenylmethane with magnesium to obtain a Grignard reagent and acetone, and then to quench with acid to obtain (2-benzyl)-phenyl-2-isopropanol, and then to obtain 10,10-dimethyldiphenylmethane through sulfuric acid condensation reaction, and then to obtain the target product 10,10-dimethylanthracenone through bromination and hydrolysis. This method requires 9 steps to obtain the crude product 10,10-dimethylanthracenone. The process is lengthy and cumbersome, and it still needs to use Grignard reagent, concentrated sulfuric acid and other environmentally harmful reagents; at the same time, although the crude product yield of this route is about 80%, the purity is not ideal. The applicant has repeatedly verified that the purity of the crude product is only about 70%, and the total yield of the product is reduced to less than 50% after crystallization and purification.

[0009] It can be seen that the existing method for preparing 10,10-dimethylanthraquinone inevitably involves reagents such as Grignard reagent, concentrated sulfuric acid, and chromium trioxide, which has high requirements for equipment, and the reaction will produce a large amount of three wastes, which is highly polluting to the environment and does not conform to the concept of green chemistry. At the same time, the price of raw materials for synthesizing 10,10-dimethylanthraquinone fluctuates greatly, and methyl 2-benzylbenzoate is in short supply, resulting in a high overall cost of the reaction route. In addition, the existing synthesis method has many steps and is more expensive.

[0010] In view of this, it is indeed necessary to propose a preparation method of 10,10-dimethylanthraquinone to solve the above problems. Summary of the invention

[0011] The object of the present invention is to provide a method for preparing 10,10-dimethylanthraquinone to solve at least one of the problems of the existing method for preparing 10,10-dimethylanthraquinone, namely, greater environmental pollution and higher reaction route cost.

[0012] To achieve the above object, the present invention provides a method for preparing 10,10-dimethylanthraquinone, and the synthetic route is:

[0013]

[0014] The solvent is an aprotic solvent, and the raw material A is a methyl metal organic compound.

[0015] Furthermore, the equivalent of the methyl metal organic compound is 1.0 to 3.0 eq, preferably 1.5 to 2.5 eq, and more preferably 2.0±0.2 eq.

[0016] Furthermore, the methylmetal organic compound includes one or a combination of dimethyl zinc, trimethyl aluminum, dimethyl titanium dichloride, and butyl lithium. The methylmetal organic compound is preferably dimethyl titanium dichloride. The applicant has found that the route of the present invention uses a specific methylmetal organic compound (such as one or a combination of dimethyl zinc, trimethyl aluminum, dimethyl titanium dichloride or butyl lithium) within a specific equivalent range (such as 1.0 to 3.0 eq) to prepare the target product with higher efficiency and higher conversion rate. Compared with the prior art, the production cycle is short, the operation is simple and convenient, the cost is greatly reduced, and the waste generation is reduced. In particular, when the preferred methylmetal organic compound is used in a specific equivalent range (such as 1.5 to 2.5 eq), the yield can be further improved to a greater extent unexpectedly, which greatly solves the economic cost problem.

[0017] Further, the aprotic solvent includes one or a combination of tetrahydrofuran, 2-methyltetrahydrofuran, dichloromethane, chloroform, anhydrous ether, 1,2-dichloroethane, methyl tert-butyl ether, and toluene. The aprotic solvent is preferably methyl tert-butyl ether, dichloromethane, and toluene.

[0018] Furthermore, the preparation method allows the raw material A to contact with 9,10-anthracene dione in a dropwise manner and react. Preferably, the preparation method comprises: a step of dropping the raw material A into a 9,10-anthracene dione solution. As a further improvement of the present invention, the temperature when dropping the raw material A is controlled at -50 to 25°C, preferably at 0 to 25°C. The reaction temperature is controlled at 20 to 25°C.

[0019] Furthermore, the reaction process of the preparation method is carried out in an inert gas atmosphere, and the inert gas includes one or a combination of nitrogen, helium, neon, argon, and krypton, and the inert gas is preferably nitrogen.

[0020] Furthermore, after the reaction of the preparation method is completed, the step of adding the reaction solution to a solution of an acidic compound for quenching is also included. As a further improvement of the present invention, the acidic compound includes one or a combination of ammonium chloride, hydrochloric acid, sulfuric acid, formic acid, and acetic acid; preferably, the concentration of an aqueous solution of ammonium chloride is 10%. As a further improvement of the present invention, the quenching temperature is preferably 0 to 5°C.

[0021] Furthermore, the preparation method further comprises the steps of extraction and concentration. As a further improvement of the present invention, the extractant used in the extraction process comprises one or a combination of ethyl acetate, dichloromethane, chloroform, methyl tert-butyl ether, chloroform, toluene, and isopropyl acetate. Preferably, the extractant is one or a combination of methyl tert-butyl ether, dichloromethane, and toluene.

[0022] Furthermore, the preparation method further comprises the step of crystallizing the crude 10,10-dimethylanthraquinone. As a further improvement of the present invention, the crystallization comprises the step of adding a polar solvent to the crude 10,10-dimethylanthraquinone to dissolve and crystallize. The polar solvent preferably comprises one or a combination of methanol, ethanol, isopropanol, and acetonitrile;

[0023] As a further improvement of the present invention, the amount of polar solvent used is about 3 to 5 times the weight of the crude 10,10-dimethylanthraquinone.

[0024] As a further improvement of the present invention, the dissolution temperature of the crude 10,10-dimethylanthraquinone is 65-80° C., the crystallization temperature is 0-5° C., and the crystallization time is 2-3 h.

[0025] To solve the above problems, the present invention also provides a method for preparing 10,10-dimethylanthraquinone, comprising the steps of: dripping 1.0 to 3.0 eq (preferably 1.5 to 2.5 eq, more preferably 2.0 ± 0.2 eq) of a methyl metal organic compound (the methyl metal organic compound is preferably selected from dimethyl zinc, trimethyl aluminum, dimethyl titanium dichloride, butyl lithium, more preferably dimethyl titanium dichloride) into 9,10-anthracene dione dissolved or dispersed in an aprotic solvent (preferably methyl tert-butyl ether, dichloromethane, toluene) under an inert gas atmosphere for reaction, wherein the dripping is preferably controlled at a temperature of -50 to 25°C, and the reaction is preferably carried out at 20 to 25°C. The preparation method may further include adding a solution of an acidic compound (e.g., an aqueous solution of ammonium chloride) to quench the reaction after the reaction is completed, extracting with methanol and / or ethanol and / or isopropanol and / or acetonitrile after quenching, heating to dissolve after extraction and cooling to crystallize to obtain 10,10-dimethylanthraquinone.

[0026] In the present invention, the equivalent range of the raw material A (methyl metal organic compound) refers to the ratio of the molar number of the raw material A to the molar number of 9,10-anthracene dione.

[0027] The beneficial effects of the present invention are as follows: the present invention uses 9,10-anthracene dione as a raw material to prepare 10,10-dimethyl anthracene dione, and the cost of the reaction route is about 30% of the cost of the existing preparation method, which greatly reduces the production cost of 10,10-dimethyl anthracene dione; at the same time, the market of 9,10-anthracene dione is mature, the supply is sufficient, and the price is cheap, so the use of 2-benzyl benzoic acid methyl ester, which is expensive and in short supply, is avoided; in addition, the preparation method of the present invention has short reaction steps, the raw materials used in the reaction are easy to obtain, and the three wastes generated after the reaction are less, thereby reducing pollution to the environment and conforming to the concept of green chemistry. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1This is the mass spectrum of 10,10-dimethylanthraquinone in Example 1.

[0029] Figure 2 This is the hydrogen nuclear magnetic resonance spectrum of 10,10-dimethylanthracenone in Example 1.

[0030] Figure 3 yes Figure 2 A local enlarged view of the dotted part of the H NMR spectrum.

[0031] Figure 4 This is the HPLC spectrum of 10,10-dimethylanthraquinone in Example 4. DETAILED DESCRIPTION

[0032] Those skilled in the art will understand that the following examples are only used to illustrate the present invention and should not be considered to limit the scope of the present invention. Some non-essential improvements and adjustments made by those skilled in the art based on the above invention content still belong to the protection scope of the present invention. If no specific technology or conditions are specified in the embodiments, the technology or conditions described in the literature in this field or the product instructions are used. If the manufacturer is not specified in the materials or equipment used, they are all conventional products that can be purchased.

[0033] Example 1

[0034] In a 250mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, 10g (48mmol, 1.0eq) of 9,10-anthracene dione and 100mL of methyl tert-butyl ether were added, and then the temperature was lowered to 0-5°C, and 36mL (72mmol, 1.5eq) of 2mol / L dimethyl zinc / ether solution was added dropwise with stirring, and the temperature was controlled not to exceed 25°C during the addition; after the addition was completed, the reaction was carried out at 20-25°C for 2h, and the temperature was lowered to 0-5°C. The reaction solution was poured into 100mL of 10% ammonium chloride solution for quenching, and 200mL of methyl tert-butyl ether was added for extraction and separation. The organic phase was dried over sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 9.5g of crude 10,10-dimethylanthraquinone.

[0035] The crude product was heated to 60-65°C with 45 mL of methanol to dissolve, then cooled to 0-5°C, crystallized for 2.5 hours, filtered, the filter cake was rinsed with 5 mL of 0-5°C cold methanol, and then vacuum dried at 40°C to obtain 5.1 g of 10,10-dimethylanthraquinone. The yield was 47.77% and the HPLC purity was 96.5%.

[0036] Mass spectra such as Figure 1 As shown, the test data is: ESI+: 223.18.

[0037] H NMR spectra Figure 2 and Figure 3 As shown, the test data is: 1 H-NMR (400MHz, CDCl 3， ppm): δ8.37(dd,2H),7.70(dd,2H),7.65(td,2H),7.44(td,2H),1.75(s,6H).

[0038] Example 2

[0039] In a 250mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, 10g (48mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane were added, and then the temperature was lowered to 0-5°C, and 36mL (72mmol, 1.5eq) of 2mol / L dimethyl zinc / ether solution was added dropwise with stirring, and the temperature was controlled not to exceed 25°C during the addition; after the addition was completed, the reaction was carried out at 20-25°C for 2h, and the temperature was lowered to 0-5°C. The reaction solution was poured into 100mL of 10% ammonium chloride solution for quenching, and 200mL of dichloromethane was added for extraction and separation. The organic phase was dried over sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 10.5g of crude 10,10-dimethylanthraquinone.

[0040] The crude product was heated to 65-70°C with 50 mL of ethanol to dissolve, cooled to 0-5°C, crystallized for 2.5 hours, filtered, the filter cake was rinsed with 5 mL of 0-5°C cold ethanol, and then vacuum dried at 40°C to obtain 4.5 g of 10,10-dimethylanthraquinone, with a yield of 42.15% and a HPLC purity of 97.1%. The mass spectrum test data was 223.18.

[0041] Example 3

[0042] In a 250mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, 10g (48mmol, 1.0eq) of 9,10-anthracene dione and 100ml of toluene were added, and then the temperature was lowered to 0-5°C, and 40mL (80mmol, 1.67eq) of 2mol / L trimethylaluminum / toluene solution was added dropwise with stirring, and the temperature was controlled not to exceed 25°C during the addition; after the addition was completed, the reaction was carried out at 20-25°C for 2h, and the temperature was lowered to 0-5°C. The reaction solution was poured into 100mL of 10% ammonium chloride solution for quenching, 200ml of toluene was added for extraction and separation, and the organic phase was dried over sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 11.2g of crude 10,10-dimethylanthraquinone.

[0043] The crude product was heated to 65-70°C with 60 ml of isopropanol to dissolve, cooled to 0-5°C, crystallized for 4 hours, filtered, the filter cake was rinsed with 5 mL of 0-5°C cold isopropanol, and then vacuum dried at 40°C to obtain 3.6 g of 10,10-dimethylanthraquinone, with a yield of 33.72% and a HPLC purity of 97.7%. The mass spectrum test data was 223.18.

[0044] Example 4

[0045] In a 250mL reaction flask equipped with a magnetic stirrer and a nitrogen gas supply, add 160mL of dichloromethane and 16.7g (88mmol) of titanium tetrachloride, stir and cool to below -30°C, add 44mL (88mmol) of 2mol / L dimethyl zinc / ether solution dropwise, and continue stirring for half an hour after the addition is complete to obtain a dimethyltitanium dichloride / dichloromethane solution for use.

[0046] Add 9.2g (44mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane to a 500mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, then cool to -25°C, and add the above-mentioned homemade dimethyl titanium dichloride solution (88mmol, 2eq) dropwise while stirring. The temperature is controlled not to exceed -15°C during the addition. After the addition is completed, slowly heat up to 20-25°C for reaction. After TLC monitoring of the complete reaction of the raw materials, cool down to 0-5°C, and pour the reaction solution into 500mL of water for quenching. After stratification, the aqueous phase is extracted with 300mL of dichloromethane, and the organic phases are combined and backwashed with 100ml of water and 100ml of sodium carbonate solution. The organic phases are collected, dried with sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 10.7g of crude 10,10-dimethylanthraquinone.

[0047] The crude product was heated to 65-70°C with 50 mL of ethanol to dissolve, cooled to 0-5°C, filtered after crystallization for 2.5 hours, the filter cake was rinsed with 5 mL of 0-5°C cold ethanol, and then vacuum dried at 40°C to obtain 7.2 g of 10,10-dimethylanthraquinone, with a yield of 73.62% and a HPLC purity of 97.5%. The mass spectrum test data was 223.18.

[0048] Example 5

[0049] In a 250mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, 36mL (72mmol, 1.5eq) of 2mol / L dimethyl zinc / ether solution was added, then the temperature was lowered to 0-5°C, and a solution prepared by adding 10g (48mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane was added dropwise under stirring, and the temperature was controlled not to exceed 25°C during the addition; after the addition was completed, the reaction was carried out at 20-25°C for 2h, and the subsequent operation was the same as in Example 1 to obtain 3.4g of 10,10-dimethyl anthracene dione. The yield was 31.85%, and the HPLC purity was 96.2%.

[0050] Example 6

[0051] In a 250mL reaction bottle equipped with a magnetic stirrer and a nitrogen gas supply, add 160mL of dichloromethane and 16.7g (88mmol) of titanium tetrachloride, stir and cool to below -30°C, add 44mL (88mmol) of 2mol / L dimethyl zinc / ether solution dropwise, and continue stirring for half an hour after the addition is complete to obtain a dimethyltitanium dichloride / dichloromethane solution for use.

[0052] Add 9.2g (44mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane to a 500mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, then cool to below -25°C, and add homemade dimethyltitanium dichloride solution (132mmol, 3.0eq) dropwise while stirring. The temperature is controlled not to exceed -15°C during the addition. After the addition is completed, slowly heat up to 20-25°C for reaction. After TLC monitoring of the complete reaction of the raw materials, cool down to 0-5°C, and pour the reaction solution into 500mL of water for quenching. After stratification, the aqueous phase is extracted with 300mL of dichloromethane, and the organic phases are combined and backwashed with 100ml of water and 100ml of sodium carbonate solution. The organic phases are collected, dried with sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 11.1g of crude 10,10-dimethylanthraquinone.

[0053] The crude product was heated to 65-70°C with 50 mL of ethanol to dissolve, cooled to 0-5°C, crystallized for 2.5 hours, filtered, the filter cake was rinsed with 5 mL of 0-5°C cold ethanol, and then vacuum dried at 40°C to obtain 3.8 g of 10,10-dimethylanthraquinone with a yield of 38.7% and an HPLC purity of 85.5%.

[0054] Comparative Example 7

[0055] Add 160ml of dichloromethane and 16.7g (88mmol) of titanium tetrachloride to a 250mL reaction bottle equipped with a magnetic stirrer and a nitrogen gas device, stir and cool to below -30°C, add 44mL (88mmol) of 2mol / L dimethyl zinc / ether solution, and continue stirring for half an hour after the addition is complete to obtain a dimethyl titanium dichloride / dichloromethane solution; then add a solution prepared by 10g (48mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane under stirring, and control the temperature not to exceed -15°C during the addition. After the addition is complete, slowly heat to 20-25°C for reaction. TLC monitoring shows that there is still residual raw material in the reaction solution, and as time goes on, the residual raw material no longer decreases, that is, the reaction is complete. The reaction solution was cooled to 0-5°C and poured into 500 mL of water for quenching. After separation, the aqueous phase was extracted twice with 300 mL of dichloromethane. The organic phases were combined and backwashed with 100 mL of water and 100 mL of sodium carbonate solution. The organic phases were collected, dried with sodium sulfate, filtered, and then concentrated to dryness at 35-45°C to obtain 9.9 g of crude 10,10-dimethylanthraquinone with an HPLC purity of only 18.5%. Recrystallization purification was not possible.

[0056] Comparative Example 8

[0057] Add 9.2g (44mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane to a 500mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, then cool to below -25°C, add 20.9g (88mmol, 2.0eq) of titanium tetrachloride dropwise under stirring, and then add 55mL (88mmol, 2.0eq) of 2mol / L dimethyl zinc / ether solution dropwise after the addition is complete. The temperature is controlled not to exceed -15°C during the addition. After the addition is complete, slowly heat to 20-25°C and react for 2h. No target product is generated by TLC monitoring. Quench to terminate the reaction.

[0058] Comparative Example 9

[0059] Add 9.2g (44mmol, 1.0eq) of 9,10-anthracene dione and 100mL of dichloromethane to a 500mL reaction bottle equipped with a magnetic stirrer, a condenser and a nitrogen gas device, then cool to below -25°C and stir, add 20.9g (88mmol, 2.0eq) of titanium tetrachloride and 55mL (88mmol, 2.0eq) of 2mol / L dimethyl zinc / ether solution to two dropping funnels, and add them dropwise to the reaction solution at the same time, and control the temperature not to exceed -15°C during the addition. After the addition is complete, slowly heat to 20-25°C and react for 2h. The target product point is not obvious when monitored by TLC. Quench to terminate the reaction.

[0060] In summary, the present invention uses 9,10-anthracene dione as a raw material to prepare 10,10-dimethyl anthracene ketone, and the cost of the reaction route is about 30% of the cost of the existing preparation method, which greatly reduces the production cost of 10,10-dimethyl anthracene ketone; at the same time, the preparation method of 9,10-anthracene dione is mature and has sufficient supply, avoiding the use of 2-benzylbenzoic acid methyl ester which is expensive and in short supply; in addition, the preparation method of the present invention has short reaction steps, the raw materials used in the reaction are easy to obtain, and the three wastes generated after the reaction are less, which reduces the pollution to the environment and conforms to the concept of green chemistry. The above embodiments are only used to illustrate the technical scheme of the present invention and are not limited. Although the present invention is described in detail with reference to the preferred embodiments, ordinary technicians in the field should understand that the technical scheme of the present invention can be modified or equivalently replaced without departing from the spirit and scope of the technical scheme of the present invention.

Claims

1. A method for preparing 10,10-dimethylanthraquinone, characterized in that: The synthetic route is as follows: The solvent is an aprotic solvent, and the raw material A is a methyl metal organic compound.

2. The method for preparing 10,10-dimethylanthraquinone according to claim 1, characterized in that: The equivalent of the methyl metal organic compound is 1.0 to 3.0 eq, preferably 1.5 to 2.5 eq.

3. The method for preparing 10,10-dimethylanthraquinone according to claim 1, characterized in that: The methyl metal organic compound includes one or a combination of dimethyl zinc, trimethyl aluminum, dimethyl titanium dichloride, and butyl lithium.

4. The method for preparing 10,10-dimethylanthracenone according to claim 1, characterized in that: The aprotic solvent includes one or a combination of tetrahydrofuran, 2-methyltetrahydrofuran, dichloromethane, chloroform, anhydrous ethyl ether, 1,2-dichloroethane, methyl tert-butyl ether, and toluene.

5. The preparation method according to any one of claims 1 to 4, characterized in that: The raw material A is contacted with 9,10-anthracene dione in a dropwise manner to carry out a reaction.

6. The preparation method according to claim 5, characterized in that: Add raw material A dropwise into the 9,10-anthracenedione solution.

7. The method for preparing 10,10-dimethylanthracenone according to claim 1, characterized in that: The reaction process is carried out in an inert gas atmosphere.

8. The method for preparing 10,10-dimethylanthraquinone according to claim 1, characterized in that: The method further comprises the step of adding the reaction solution into a solution of an acidic compound for quenching after the reaction is completed.

9. The method for preparing 10,10-dimethylanthracenone according to claim 7, characterized in that: The method also includes the steps of extraction and concentration after quenching the reaction.

10. The method for preparing 10,10-dimethylanthraquinone according to claim 1, characterized in that: Also includes: Steps for crystallizing crude 10,10-dimethylanthracnone.

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