Catalyst for acylation reaction, and preparation method therefor and use thereof

Abstract

A catalyst for an acylation reaction, and a preparation method therefor and the use thereof. The preparation method for the catalyst for an acylation reaction comprises the following steps: (1) adding a cation exchange resin to a 0.1-10 mol / L hydrochloric acid solution, performing an ultrasonic treatment for 1-60 min followed by filtration, washing same with water until the filtrate is neutral, and filtering same; and (2) adding the cation exchange resin, which is obtained after the treatment in step (1), to a chromatographic column, adding a 0.01-5 mol / L Lewis acid solution for leaching, filtering same, then washing same with water, and drying same to obtain a catalyst for an acylation reaction. The catalyst for an acylation reaction can efficiently achieve an acylation catalytic reaction of a naphthalene-containing compound and has a good catalytic effect, and the post-treatment is simple.

Description

Acylation reaction catalyst and its preparation method and application Technical Field

[0001] The invention belongs to the field of fine chemicals, and particularly relates to an acylation reaction resin catalyst and a preparation method and application thereof. Background Art

[0002] Aromatic ketones are important chemical intermediates with widespread applications in pharmaceuticals, dyes, pesticides, and other fields. For example, 2-acyl-6-methoxynaphthalene is used in the synthesis of the anti-inflammatory analgesic drug naproxen. Ortho-hydroxybenzophenones, as highly effective and broad-spectrum UV absorbers, are widely used in industries such as plastics, resins, coatings, synthetic rubber, and cosmetics. The Friedel-Crafts reaction is a key method for synthesizing aromatic ketones.

[0003] The Friedel-Crafts reaction is one of the most important reactions in organic chemistry. It involves the introduction of alkyl or acyl groups onto aromatic compounds under the catalysis of protic or Lewis acids. The introduction of an alkyl group is called an alkylation reaction, while the introduction of an acyl group is called an acylation reaction. Friedel and Crafts discovered and confirmed that aluminum chloride is an effective catalyst for the acylation of aromatic compounds. Although this reaction was discovered relatively early, research in this area remains active, particularly in the development of new catalysts.

[0004] Currently, Lewis acids, such as AlCl₃ and FeCl₃, are widely used acylation catalysts. However, these catalysts form complexes with the product during the reaction, increasing catalyst usage. Separation of the catalyst from the product is difficult, and regeneration is impossible. Post-processing produces large amounts of acidic wastewater, polluting the environment. Supported catalysts, formed by loading Lewis acids onto solid acids, are another research direction, overcoming the drawbacks of traditional catalysts, such as difficult product separation and severe environmental pollution. Researchers have loaded aluminum chloride onto supports such as clay, molecular sieves, and mesoporous silica to investigate its activity and selectivity in the Friedel-Crafts reaction. The results showed that the supported catalysts exhibited superior activity and selectivity to unsupported catalysts. Mitsui & Co. has synthesized highly selective anthraquinone using various modified molecular sieves. Furthermore, researchers have used zeolite molecular sieves to synthesize anthraquinone under gas-solid heterogeneous catalysis. However, this method lacks precise control over the material ratio, and the reaction apparatus is not suitable for industrial production. In addition, ion exchange resins, solid superacids, solid heteropolyacids, ionic liquids, etc. have been reported in the literature to be used to catalyze Friedel-Crafts acylation reactions, but they have disadvantages such as poor stability, high price, difficulty in preparation, and poor catalytic effect.

[0005] Based on the above status quo and shortcomings, it is very necessary to develop a class of environmentally friendly, highly efficient and easy-to-prepare acylation catalysts.

[0006] Summary of the Invention

[0007] To address technical issues such as the complexity of conventional acylation reaction catalytic systems, difficulty in product separation, and poor catalytic effects, the present invention provides an acylation reaction catalyst, a preparation method, and applications thereof. The acylation reaction catalyst can efficiently achieve acylation of naphthalene-containing compounds, exhibits good catalytic effects, and simplifies post-processing.

[0008] In order to achieve the above object, the present invention provides a method for preparing an acylation reaction catalyst, which comprises the following steps:

[0009] (1) Add the cation exchange resin to a 0.1 mol / L-10 mol / L hydrochloric acid solution, sonicate for 1-60 min, filter, wash with water until the filtrate is neutral, and filter;

[0010] (2) adding the cation exchange resin obtained in step (1) into a chromatography column, adding 0.01 mol / L-5 mol / L Lewis acid solution for elution, filtering, washing with water, and drying to obtain the acylation reaction catalyst.

[0011] According to a specific embodiment of the present invention, preferably, the cation exchange resin includes a hydrogen-type strongly acidic styrene-based cation exchange resin and / or a sodium-type strongly acidic styrene-based cation exchange resin.

[0012] According to a specific embodiment of the present invention, preferably, the cation exchange resin includes one or a combination of two or more of 732 cationic resin, 734 cationic resin, D001 cationic resin, Amberlite-113, Amberlyst-15, Amberlyst-35, Amberlyst-16, Amberlyst-36, Amberlyst-45, and Amberlyst-46.

[0013] According to a specific embodiment of the present invention, preferably, the Lewis acid includes Al 3+ 、Fe 3+ 、Zn 2+ 、Cu 2+ 、Ni 2+ One or a combination of two or more of the hydrochloride, hydrobromide and nitrate of

[0014] According to a specific embodiment of the present invention, preferably, in step (1), the concentration of the hydrochloric acid solution is 1 mol / L-6 mol / L.

[0015] According to a specific embodiment of the present invention, preferably, in step (1), the solid-liquid mass ratio of the cation exchange resin to the hydrochloric acid solution is 1:1-1:10, more preferably 1:2-1:5.

[0016] According to a specific embodiment of the present invention, preferably, in step (1), the ultrasonic time is 10-30 min.

[0017] According to a specific embodiment of the present invention, preferably, in step (1), the ultrasonic frequency is 60KHz-150KHz, and the ultrasonic temperature is 30-60°C.

[0018] According to a specific embodiment of the present invention, preferably, in step (2), the Lewis acid solution is Al 3+ 、Fe 3+ 、Zn 2+ 、Cu 2+ 、Ni 2+ A metal salt solution of one or a combination of two or more of hydrochloride, hydrobromide, and nitrate.

[0019] According to a specific embodiment of the present invention, preferably, the concentration of the Lewis acid solution is 0.02-2 mol / L.

[0020] According to a specific embodiment of the present invention, preferably, in step (2), the volume ratio of the Lewis acid solution to the cation exchange resin is 50:1-2:1, more preferably 20:1-5:1.

[0021] According to a specific embodiment of the present invention, preferably, in step (2), during elution, the flow rate of the Lewis acid solution is 5 mL / min-50 mL / min, more preferably 10 mL / min-20 mL / min.

[0022] The present invention also provides an acylation reaction catalyst prepared by the above preparation method.

[0023] The present invention also provides application of the acylation reaction catalyst in catalyzing aryl acylation.

[0024] According to a specific embodiment of the present invention, preferably, the reaction of the aryl acylation is as follows:

[0025] Wherein, A is the raw material naphthalene, B or C is the acylating agent, and D is the acylated naphthalene product; R 1 is selected from H, C1-C5 alkyl, C1-C4 alkoxy, halogen, hydroxyl, R 1 The number of substitutions is 0-7; R 2 is selected from C1-C5 alkyl, phenyl, phenylmethylene; X is Cl or Br.

[0026] According to a specific embodiment of the present invention, preferably, the aryl acylation reaction comprises the following steps:

[0027] The raw material naphthalene, the acylation agent and the acylation reaction catalyst are added to a solvent, and stirred at 60-100° C. for reaction for 1-24 hours to obtain an acylated naphthalene product, and the acylation reaction catalyst is recovered by filtration.

[0028] According to a specific embodiment of the present invention, preferably, the molar ratio of the raw material naphthalene to the acylating agent is 1:1-1:4, and the mass ratio of the acylation reaction catalyst to the raw material naphthalene is 1:20-1:4.

[0029] According to a specific embodiment of the present invention, preferably, the solvent is one or a combination of two or more of nitrobenzene, chlorobenzene, and dichlorobenzene, and the mass ratio of the solvent to the raw material naphthalene is 2:1-10:1.

[0030] The present invention has the following beneficial effects:

[0031] (1) The acylation reaction catalyst of the present invention can efficiently realize the acylation catalytic reaction of naphthalene-containing compounds by modifying the cationic resin with metal ions, has good catalytic effect, and the post-processing of the reaction system is simple, thereby avoiding the problem of product adsorption and separation difficulties caused by the use of AlCl3 catalyst in the prior art;

[0032] (2) The preparation method of the acylation reaction catalyst of the present invention is simple and economical, and can be widely used. DETAILED DESCRIPTION

[0033] In order to have a clearer understanding of the technical features, objectives and beneficial effects of the present invention, the technical solution of the present invention is now described in detail below, but it should not be understood as limiting the scope of implementation of the present invention.

[0034] Unless otherwise specified, the reagents, methods, instruments and equipment used in the present invention are conventional reagents, methods, instruments and equipment in the art.

[0035] Unless otherwise specified, the reagents and materials used in the following examples were commercially available and of analytical grade.

[0036] Preparation Example 1

[0037] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0038] 100 g of Amberlyst-15 resin was added to 200 mL of 1 mol / L hydrochloric acid solution, ultrasonicated (frequency: 100 Hz, temperature: 45°C) for 30 min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to a chromatography column and eluted with 2000 mL of 0.2 mol / L AlCl3 solution at a flow rate of 20 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate, and dried to obtain resin catalyst Cat-1.

[0039] Preparation Example 2

[0040] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0041] 100 g of 734 cationic resin was added to 150 mL of 6 mol / L hydrochloric acid solution, ultrasonicated (frequency: 120 Hz, temperature: 60°C) for 10 min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to a chromatography column and eluted with 800 mL of 1 mol / L ZnCl2 solution at a flow rate of 10 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate, and dried to obtain resin catalyst Cat-2.

[0042] Preparation Example 3

[0043] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0044] 100 g of D001 cationic resin was added to 500 mL of 3 mol / L hydrochloric acid solution, ultrasonicated (frequency: 130 Hz, temperature: 55°C) for 40 min, filtered, and washed with deionized water until the filtrate was neutral. The resulting resin was added to a chromatography column and eluted with 1600 mL of 2 mol / L ZnCl2 solution at a flow rate of 15 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate and dried to obtain resin catalyst Cat-3.

[0045] Preparation Example 4

[0046] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0047] 100 g of Amberlyst-45 cationic resin was added to 1000 mL of 5 mol / L hydrochloric acid solution, ultrasonicated (frequency: 80 Hz, temperature: 50°C) for 30 min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to a chromatography column and eluted with 1000 mL of 1.5 mol / L AlCl3 solution at a flow rate of 20 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate, and dried to obtain resin catalyst Cat-4.

[0048] Preparation Example 5

[0049] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0050] 100 g of Amberlite-113 cationic resin was added to 700 mL of 0.2 mol / L hydrochloric acid solution, ultrasonicated (frequency: 100 Hz, temperature: 35°C) for 60 min, filtered, and washed with deionized water until the filtrate was neutral. The resulting resin was added to a chromatography column and eluted with 1400 mL of 2.5 mol / L NiBr2 solution at a flow rate of 10 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate, and dried to obtain resin catalyst Cat-5.

[0051] Preparation Example 6

[0052] This preparation example provides an acylation reaction resin catalyst, which is prepared by the following steps:

[0053] 100g of Amberlyst-36 cationic resin was added to 800mL of 4mol / L hydrochloric acid solution, ultrasonicated (frequency of 150Hz, temperature of 60℃) for 25min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to a chromatography column and eluted with 1800mL of 2.5mol / L Cu(NO3)2 solution at a flow rate of 16mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate, and dried to obtain the resin catalyst Cat-6.

[0054] Example 1

[0055] 2-Methylnaphthalene, propionyl chloride, nitrobenzene and resin catalyst Cat-1 were added to a reactor, wherein the amount of 2-methylnaphthalene was 100 g, the molar ratio of 2-methylnaphthalene to propionyl chloride was 1:2, the mass ratio of Cat-1 to 2-methylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-methylnaphthalene was 5:1. The reaction was carried out at 80° C. for 12 hours. After filtering, concentration, separation and purification, the yield of the propionylation product was 75%.

[0056] Example 2

[0057] 2-Methoxynaphthalene, acetic anhydride, nitrobenzene and resin catalyst Cat-3 were added to a reactor, wherein the amount of 2-methoxynaphthalene was 100 g, the molar ratio of 2-methoxynaphthalene to acetic anhydride was 1:4, the mass ratio of Cat-3 to 2-methoxynaphthalene was 1:4, and the mass ratio of nitrobenzene to 2-methoxynaphthalene was 10:1. The reaction was carried out at 75° C. for 24 hours. After filtering, concentration, separation and purification, the yield of the acetylated product was 81%.

[0058] Example 3

[0059] 1-Bromo-4-ethylnaphthalene, benzoyl chloride, dichlorobenzene and resin catalyst Cat-6 were added to a reactor, wherein the amount of 1-bromo-4-ethylnaphthalene was 100 g, the molar ratio of 1-bromo-4-ethylnaphthalene to benzoyl chloride was 1:2.5, the mass ratio of Cat-6 to 1-bromo-4-ethylnaphthalene was 1:8, and the mass ratio of dichlorobenzene to 1-bromo-4-ethylnaphthalene was 5:1. The reaction was carried out at 100° C. for 20 hours. After filtering, concentration, separation and purification, the yield of the benzoylation product was 69%.

[0060] Example 4

[0061] 1-Ethylnaphthalene, acetyl chloride, chlorobenzene and resin catalyst Cat-1 were added to a reactor, wherein the amount of 1-ethylnaphthalene was 100 g, the molar ratio of 1-ethylnaphthalene to acetyl chloride was 1:1, the mass ratio of Cat-1 to 1-ethylnaphthalene was 1:20, and the mass ratio of chlorobenzene to 1-ethylnaphthalene was 2:1. The reaction was carried out at 85° C. for 22 hours. After filtering, concentration, separation and purification, the yield of the acetylated product was 71%.

[0062] Example 5

[0063] 2-isopropylnaphthalene, isobutyric anhydride, nitrobenzene and resin catalyst Cat-1 were added to a reactor, wherein the amount of 2-isopropylnaphthalene was 100 g, the molar ratio of 2-isopropylnaphthalene to isobutyric anhydride was 1:2, the mass ratio of Cat-1 to 2-isopropylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-isopropylnaphthalene was 3:1. The reaction was carried out at 85° C. for 18 hours. After filtering, concentration, separation and purification, the yield of the acylated product was 82%.

[0064] Comparative Example 1

[0065] 100 g of Amberlyst-15 resin was added to 200 mL of 1 mol / L hydrochloric acid solution, soaked for 30 min, filtered, and washed with deionized water until the filtrate was neutral. The resulting resin was added to a chromatography column and eluted with 2000 mL of 0.2 mol / L AlCl3 solution at a flow rate of 20 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate and dried to obtain the resin catalyst Cat-c1.

[0066] 2-Methylnaphthalene, propionyl chloride, nitrobenzene and resin catalyst Cat-c1 were added to a reactor, wherein the amount of 2-methylnaphthalene was 100 g, the molar ratio of 2-methylnaphthalene to propionyl chloride was 1:2, the mass ratio of Cat-c1 to 2-methylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-methylnaphthalene was 5:1. The reaction was carried out at 80°C for 12 hours. After filtering, concentration, separation and purification, the yield of the propionylation product was 43%.

[0067] Comparative Example 2

[0068] 100 g of Amberlyst-15 resin was added to 200 mL of 1 mol / L hydrochloric acid solution, ultrasonicated (frequency: 100 Hz, temperature: 45°C) for 30 min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to 2000 mL of 0.2 mol / L AlCl3 solution, soaked for 2 hours, filtered, and then washed with deionized water until there was no metal ion in the filtrate. Drying gave the resin catalyst Cat-c2.

[0069] 2-Methylnaphthalene, propionyl chloride, nitrobenzene and resin catalyst Cat-c2 were added to a reactor, wherein the amount of 2-methylnaphthalene was 100 g, the molar ratio of 2-methylnaphthalene to propionyl chloride was 1:2, the mass ratio of Cat-c2 to 2-methylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-methylnaphthalene was 5:1. The reaction was carried out at 80°C for 12 hours. After filtering, concentration, separation and purification, the yield of the propionylation product was 38%.

[0070] Comparative Example 3

[0071] 100 g of D001 cationic resin was added to 500 mL of 3 mol / L hydrochloric acid solution, ultrasonicated (frequency: 40 Hz, temperature: 25°C) for 40 min, filtered, and washed with deionized water until the filtrate was neutral. The obtained resin was added to a chromatography column and eluted with 1600 mL of 2 mol / L ZnCl2 solution at a flow rate of 15 mL / min. The resin was then washed with deionized water until there was no metal ion in the filtrate and dried to obtain the resin catalyst Cat-c3.

[0072] 2-Methoxynaphthalene, acetic anhydride, nitrobenzene and resin catalyst Cat-c3 were added to a reactor, wherein the amount of 2-methoxynaphthalene was 100 g, the molar ratio of 2-methoxynaphthalene to acetic anhydride was 1:4, the mass ratio of Cat-c3 to 2-methoxynaphthalene was 1:4, and the mass ratio of nitrobenzene to 2-methoxynaphthalene was 10:1. The reaction was carried out at 75° C. for 24 hours. After filtering, concentration, separation and purification, the yield of the acetylated product was 48%.

[0073] Comparative Example 4

[0074] 2-isopropylnaphthalene (100 g), isobutyric anhydride, nitrobenzene and Amberlyst-15 resin were added to a reactor, wherein the molar ratio of 2-isopropylnaphthalene to isobutyric anhydride was 1:2, the mass ratio of Amberlyst-15 to 2-isopropylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-isopropylnaphthalene was 3:1. The reaction was carried out at 85° C. for 18 hours. After filtration, concentration, separation and purification, the yield of the acylated product was 12%.

[0075] Comparative Example 5

[0076] At low temperature, a nitrobenzene solution of AlCl3 and isobutyric anhydride, and a nitrobenzene solution of 2-isopropylnaphthalene (100 g) were prepared respectively, wherein the molar ratio of 2-isopropylnaphthalene to isobutyric anhydride was 1:2, the mass ratio of aluminum chloride to 2-isopropylnaphthalene was 1:10, and the mass ratio of nitrobenzene to 2-isopropylnaphthalene was 3:1. The mixture was reacted at 85°C for 18 hours. After quenching, filtering, concentrating, and separation and purification, the yield of the acylated product was 62%. After quenching the reaction, flocs were generated, which affected the separation effect and adsorbed the product, resulting in a reduced yield.

[0077] It can be seen from the results of the above examples and comparative examples that the present invention can effectively catalyze the acylation reaction of naphthalene compounds, greatly improve the conditions of the acylation reaction, simplify the operation process, and has obvious technical advantages.

[0078] Although the present invention has been described in detail above using general explanations, specific embodiments, and experiments, it will be apparent to those skilled in the art that modifications and improvements may be made based on the present invention. Therefore, such modifications and improvements, which do not depart from the spirit of the present invention, are intended to be within the scope of protection claimed herein.

Claims

1. A preparation method of an acylation reaction catalyst, which comprises the following steps: (1) Add cation exchange resin into a 0.1 mol / L - 10 mol / L hydrochloric acid solution, ultrasonic for 1 - 60 min and then filter, wash with water until the filtrate is neutral, and filter; (2) Add the cation exchange resin obtained in step (1) into a chromatography column, add a 0.01 mol / L - 5 mol / L Lewis acid solution for elution, filter, wash with water and dry to obtain the acylation reaction catalyst.

2. The preparation method according to claim 1, wherein, the cation exchange resin includes hydrogen - type strongly acidic styrene - based cation exchange resin and / or sodium - type strongly acidic styrene - based cation exchange resin.

3. The preparation method according to claim 2, wherein, the cation exchange resin includes one or a combination of two or more of 732 cation resin, 734 cation resin, D001 cation resin, Amberlite - 113, Amberlyst - 15, Amberlyst - 35, Amberlyst - 16, Amberlyst - 36, Amberlyst - 45, Amberlyst - 46.

4. The preparation method according to claim 1, wherein, The Lewis acid includes Al 3+ , Fe 3+ , Zn 2+ , Cu 2+ , Ni 2+ or a combination of one or more of its hydrochloride, hydrobromide, and nitrate salts.

5. The preparation method according to claim 1, wherein, In step (1), the concentration of the hydrochloric acid solution is 1 mol / L - 6 mol / L.

6. The preparation method according to claim 1, wherein, In step (1), the solid - liquid mass ratio of the cation exchange resin to the hydrochloric acid solution is 1:1 - 1:

10.

7. The preparation method according to claim 1, wherein, In step (1), the solid - liquid mass ratio of the cation exchange resin to the hydrochloric acid solution is 1:2 - 1:

5.

8. The preparation method according to claim 1, wherein, In step (1), the ultrasonic time is 10 - 30 min.

9. The preparation method according to claim 1, wherein, In step (1), the ultrasonic frequency is 60 KHz - 150 KHz, and the ultrasonic temperature is 30 - 60 °C.

10. The preparation method according to claim 1, wherein, In step (2), the Lewis acid solution is Al 3+ , Fe 3+ , Zn 2+ , Cu 2+ , Ni 2+ metal salt solution which is a combination of one or more of hydrochlorides, hydrobromides, and nitrates.

11. The preparation method according to claim 1, wherein, The concentration of the Lewis acid solution is 0.02 - 2 mol / L.

12. The preparation method according to claim 1, wherein, In step (2), the volume ratio of the Lewis acid solution to the cation exchange resin is 50:1 - 2:

1.

13. The preparation method according to claim 1, wherein, In step (2), the volume ratio of the Lewis acid solution to the cation exchange resin is 20:1 - 5:

1.

14. The preparation method according to claim 1, wherein, In step (2), during elution, the flow rate of the Lewis acid solution is 5 mL / min - 50 mL / min.

15. The preparation method according to claim 1, wherein, In step (2), during elution, the flow rate of the Lewis acid solution is 10 mL / min - 20 mL / min.

16. The acylation reaction catalyst prepared by the preparation method according to any one of claims 1-15.

17. Use of the acylation reaction catalyst according to claim 16 in the catalysis of aryl acylation.

18. According to the use described in claim 17, wherein, The reaction of the aryl acylation is as follows: wherein A is the raw material naphthalene, B or C is the acylation reagent, and D is the acylated naphthalene product; R 1 selected from H, C 1 -C 5 alkyl, C 1 -C 4 alkoxy, halogen, hydroxy, R 1 has a substitution number of 0 - 7; R 2 is selected from C 1 -C 5 alkyl, phenyl, phenylmethylene; X is Cl or Br.

19. According to the use described in claim 18, wherein, the reaction of the aryl acylation comprises the following steps: Adding the raw material naphthalene, the acylation reagent, and the acylation reaction catalyst into a solvent, stirring and reacting at 60-100 °C for 1-24 hours to obtain the acylated naphthalene product, and the acylation reaction catalyst is recovered by filtration.

20. According to the use described in claim 19, wherein, the molar ratio of the raw material naphthalene to the acylation reagent is 1:1-1:4, and the mass ratio of the acylation reaction catalyst to the raw material naphthalene is 1:20-1:

4.

21. According to the use described in claim 19, wherein, the solvent is one or a combination of two or more of nitrobenzene, chlorobenzene, and dichlorobenzene, and the mass ratio of the solvent to the raw material naphthalene is 2:1-10:1.

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