阅读说明：本技术 一种1,2-环己二酮的制备方法 (Preparation method of 1, 2-cyclohexanedione ) 是由 汤须崇 赵应伟 谢清萍 于 2021-09-16 设计创作，主要内容包括：本发明属于化学合成技术领域,尤其涉及一种1,2-环己二酮的制备方法。本发明提供了一种1,2-环己二酮的制备方法,包括以下步骤：将环已酮、溴代试剂、碱性催化剂和极性有机溶剂混合进行溴代反应,得到2,6-二溴环己酮；将所述2,6-二溴环己酮、无机碱、极性溶剂混合进行水解反应,得到所述1,2-环己二酮。本发明提供的制备方法以环己酮和溴代试剂为原料,通过依次进行溴代反应和水解反应能够制备得到高收率和高纯度的1,2-环己二酮,本发明提供的制备方法原料简单易得,适宜工业化生产。(The invention belongs to the technical field of chemical synthesis, and particularly relates to a preparation method of 1, 2-cyclohexanedione. The invention provides a preparation method of 1, 2-cyclohexanedione, which comprises the following steps: mixing cyclohexanone, a bromination reagent, an alkaline catalyst and a polar organic solvent for bromination reaction to obtain 2, 6-dibromocyclohexanone; and mixing the 2, 6-dibromocyclohexanone, inorganic alkali and a polar solvent for hydrolysis reaction to obtain the 1, 2-cyclohexanedione. The preparation method provided by the invention takes cyclohexanone and a bromization reagent as raw materials, and can prepare the high-yield and high-purity 1, 2-cyclohexanedione by carrying out bromination reaction and hydrolysis reaction in sequence.)

1. A preparation method of 1, 2-cyclohexanedione is characterized by comprising the following steps:

mixing cyclohexanone, a bromination reagent, a catalyst and a polar organic solvent for bromination reaction to obtain 2, 6-dibromocyclohexanone;

and mixing the 2, 6-dibromocyclohexanone, inorganic alkali and a polar solvent for hydrolysis reaction to obtain the 1, 2-cyclohexanedione.

2. The method of claim 1, wherein the brominating agent comprises one or more of N-bromosuccinimide, phenyltrimethylammonium tribromide, dibromoisocyanuric acid, liquid bromine, N-bromoacetamide, N-bromosuccinimide, and benzylammonium tribromide.

3. The method according to claim 1, wherein the catalyst is one or more of an alkali metal salt, an ammonium salt and triethylamine.

4. The preparation method according to claim 1 to 3, wherein the molar ratio of the cyclohexanone to the brominating agent to the catalyst is 1 (1 to 5) to (1 to 5).

5. The method according to claim 1, wherein the inorganic base comprises an inorganic strong base and/or an alkali metal carbonate.

6. The preparation method according to claim 1 or 5, wherein the molar ratio of the 2, 6-dibromocyclohexanone to the inorganic base is 1 (1-3).

7. The method according to claim 1, wherein the bromination reaction and the hydrolysis reaction are independently carried out at a temperature of 20 to 40 ℃.

8. The preparation method according to claim 1, wherein the polar organic solvent used for the bromination reaction comprises any one or more of methyl chloride, acetonitrile, diethyl ether, tetrahydrofuran and petroleum ether.

9. The method of claim 1, wherein the polar solvent used in the hydrolysis reaction comprises one or more of methyl chloride, lower alcohol, acetonitrile, tetrahydrofuran, benzene, nitromethane, toluene, and water.

10. The preparation method according to claim 1 or 9, wherein the molar ratio of the 2, 6-dibromocyclohexanone to the polar solvent used in the hydrolysis reaction is 1 (1-3).

Technical Field

The invention belongs to the technical field of chemical synthesis, and particularly relates to a preparation method of 1, 2-cyclohexanedione.

Background

The 1, 2-cyclohexanedione is a chemical raw material with a sweet aroma, can be used for synthesizing spices, and can also be used as an intermediate for synthesizing some heterocyclic compounds.

The cyclohexanone oxidation process is a classical process for the preparation of 1, 2-cyclohexanedione and is now the only process that can be used industrially. The method uses equivalent selenium dioxide as an oxidant, and the yield is usually between 30 and 50 percent. Because selenium dioxide is expensive, the 1, 2-cyclohexanedione produced by the method is expensive and exceeds 2000 yuan/kg; moreover, selenium dioxide has toxicity equivalent to arsenic, and selenium residues generated after reaction are difficult to treat, thereby causing serious environmental pollution.

Chinese patent CN112441891A discloses that a catalyst and a special ligand are used to oxidize cyclohexanone, and then 1, 2-cyclohexanedione is obtained by vacuum rectification, the used catalyst is a copper salt catalyst, and the ligand is a beta-diketoimine ligand, although the yield of 1, 2-cyclohexanedione is high, the catalyst is complex to synthesize, the cost is high, and the catalyst is not suitable for industrial production.

The method for synthesizing 1, 2-cyclohexanedione by catalyzing cyclohexanone with elemental iodine reported in Chinese patent CN108840790A only uses cyclohexanone as a raw material, but needs a large amount of iodine, and is not suitable for industrial production because the yield of 1, 2-cyclohexanedione is low.

Disclosure of Invention

In view of the above, the invention provides a preparation method of 1, 2-cyclohexanedione, and the preparation method provided by the invention has the advantages that raw materials are conventionally and easily available, the yield and the purity of the 1, 2-cyclohexanedione are high, and the preparation method is suitable for industrial production.

In order to achieve the above object, the present invention provides the following technical solutions:

the invention provides a preparation method of 1, 2-cyclohexanedione, which comprises the following steps:

mixing cyclohexanone, a bromination reagent, a catalyst and a polar organic solvent for bromination reaction to obtain 2, 6-dibromocyclohexanone;

and mixing the 2, 6-dibromocyclohexanone, inorganic alkali and a polar solvent for hydrolysis reaction to obtain the 1, 2-cyclohexanedione.

Preferably, the brominating reagent comprises one or more of N-bromosuccinimide, phenyltrimethylammonium tribromide, dibromoisocyanuric acid, liquid bromine, N-bromoacetamide, N-bromosuccinimide and benzyltribromoammonium salt.

Preferably, the catalyst is one or more of alkali metal salt, ammonium salt and triethylamine.

Preferably, the molar ratio of the cyclohexanone to the brominating agent to the catalyst is 1 (1-5) to (1-5).

Preferably, the inorganic base comprises an inorganic strong base and/or an alkali metal carbonate.

Preferably, the molar ratio of the 2, 6-dibromocyclohexanone to the inorganic base is 1 (1-3).

Preferably, the temperature of the bromination reaction and the hydrolysis reaction is independently 20-40 ℃.

Preferably, the polar organic solvent used in the bromination reaction includes any one or more of methyl chloride, acetonitrile, diethyl ether, tetrahydrofuran and petroleum ether.

Preferably, the polar solvent used in the hydrolysis reaction comprises one or more of methyl chloride, lower alcohol, acetonitrile, tetrahydrofuran, benzene, nitromethane, toluene and water.

Preferably, the molar ratio of the 2, 6-dibromocyclohexanone to the polar solvent used in the hydrolysis reaction is 1 (1-3).

The invention provides a preparation method of 1, 2-cyclohexanedione, which comprises the following steps: mixing cyclohexanone, a bromination reagent, an alkaline catalyst and a polar organic solvent for bromination reaction to obtain 2, 6-dibromocyclohexanone; and mixing the 2, 6-dibromocyclohexanone, inorganic alkali and a polar solvent for hydrolysis reaction to obtain the 1, 2-cyclohexanedione. The preparation method provided by the invention takes cyclohexanone and a bromization reagent as raw materials, and is easy to obtain, and the 1, 2-cyclohexanedione with high yield and high purity can be prepared by carrying out bromination reaction and hydrolysis reaction in sequence.

Drawings

FIG. 1 is a nuclear magnetic spectrum of a 1, 2-cyclohexanedione product prepared in example 1 of the present invention.

FIG. 2 is a gas chromatogram of 1, 2-cyclohexanedione prepared in example 1 of the present invention.

Detailed Description

The invention provides a preparation method of 1, 2-cyclohexanedione, which comprises the following steps:

mixing cyclohexanone, a bromination reagent, an alkaline catalyst and a polar organic solvent for bromination reaction to obtain 2, 6-dibromocyclohexanone;

and mixing the 2, 6-dibromocyclohexanone, inorganic alkali and a polar solvent for hydrolysis reaction to obtain the 1, 2-cyclohexanedione.

In the present invention, the starting materials are all commercially available products well known to those skilled in the art, unless otherwise specified.

The invention mixes cyclohexanone, a bromination reagent, a catalyst and a polar organic solvent (hereinafter referred to as a first mixture) to carry out bromination reaction, and obtains the 2, 6-dibromo cyclohexanone.

In the present invention, the brominating agent preferably includes one or more of N-bromosuccinimide, phenyltrimethylammonium tribromide, dibromoisocyanuric acid, liquid bromine, N-bromoacetamide, N-bromosuccinimide, and benzyltribromoammonium salt, and more preferably includes one or more of N-bromosuccinimide, phenyltrimethylammonium tribromide, dibromoisocyanuric acid, liquid bromine, N-bromoacetamide, and benzyltribromoammonium salt. In the present invention, when the brominating agent preferably includes two or more of the above-mentioned substances, the molar ratio of the specific substances is not particularly required in the present invention.

In the invention, the molar ratio of the cyclohexanone to the brominating agent is preferably 1 (1-5), more preferably 1 (1.5-4.5), and most preferably 1 (2.5-3).

In the present invention, the catalyst is preferably one or more of an alkali metal salt, preferably a carbonate, preferably potassium carbonate, or an alkoxide, preferably sodium methoxide, and an ammonium salt, preferably one or more of ammonium carbonate, ammonium sulfate, and ammonium bicarbonate, and triethylamine. In the present invention, the catalyst is more preferably one or more of potassium carbonate, sodium methoxide, ammonium carbonate, ammonium sulfate, ammonium bicarbonate and triethylamine, and most preferably one or more of potassium carbonate, sodium methoxide, ammonium sulfate and triethylamine; in the present invention, when the catalyst preferably includes two or more of the above-mentioned substances, the present invention has no particular requirement on the amount ratio of the substances of the specific substances.

The invention preferably adopts the substances as the basic catalyst, has no harm of heavy metal pollution, and realizes the green synthesis of the 1, 2-cyclohexanedione.

In the invention, the molar ratio of the cyclohexanone to the basic catalyst is 1 (1-5), more preferably 1 (1.5-4.5), and most preferably 1 (2-3).

In the present invention, the polar organic solvent used for the bromination reaction preferably includes any one or more of methyl chloride, acetonitrile, diethyl ether, tetrahydrofuran and petroleum ether, the methyl chloride preferably includes dichloromethane and/or chloroform, and the polar organic solvent more preferably includes any one or more of dichloromethane, acetonitrile, diethyl ether, tetrahydrofuran and petroleum ether; in the present invention, when the polar organic solvent preferably includes two or more of the above substances, there is no particular requirement for the amount ratio of the specific substances in the present invention.

In the invention, the volume ratio of the mass of the cyclohexanone to the polar organic solvent is preferably (3-35) g (100-400) mL, and more preferably (1-6) g (20-80) mL.

In the present invention, the first mixing is preferably performed by dissolving the cyclohexanone, the brominating agent and the catalyst in the polar organic solvent, and the present invention has no special requirement on the dissolving order of the cyclohexanone, the brominating agent and the catalyst.

In the invention, the temperature of the bromination reaction is preferably 20-40 ℃, more preferably 25-30 ℃, the time of the bromination reaction is preferably 2-3 h, the bromination reaction is preferably carried out under the condition of stirring, and the specific implementation process of the stirring is not specially required. In the invention, due to the electron withdrawing effect of the ketone functional group in the cyclohexanone structure, 2, 6-dibromo cyclohexanone is mainly generated when reacting with a bromization reagent.

The invention preferably carries out post-treatment on the system after the bromination reaction to obtain the 2, 6-dibromo cyclohexanone. In the present invention, the post-treatment preferably comprises sequentially: performing solid-liquid separation, collecting filtrate for extraction and removing an extracting agent; in the invention, the solid-liquid separation is preferably filtration, and the invention has no special requirements on the specific implementation process of the filtration; in the present invention, the extraction solvent is preferably ethyl acetate, and in the present invention, the volume ratio of the ethyl acetate to the filtrate is preferably 0.5: 1, the invention preferably extracts the target product 2, 6-dibromocyclohexanone into the extractant phase by extraction. The method preferably comprises the step of removing the extractant by rotary evaporation to obtain the 2, 6-dibromocyclohexanone solid, wherein the rotary evaporation temperature is preferably 38-45 ℃, and the rotary evaporation time has no special requirement so as to remove the extractant cleanly.

After obtaining the 2, 6-dibromocyclohexanone, the invention mixes the 2, 6-dibromocyclohexanone, inorganic base and polar solvent (hereinafter referred to as second mixture) to carry out hydrolysis reaction, and obtains the 1, 2-cyclohexanedione.

In the present invention, the inorganic base preferably includes an inorganic strong base preferably including sodium hydroxide and/or potassium hydroxide and/or an alkali metal carbonate preferably including sodium carbonate and/or potassium carbonate, and in the present invention, the inorganic base more preferably includes one or more of sodium hydroxide, potassium hydroxide, sodium carbonate and potassium carbonate, and in the present invention, when the inorganic base preferably includes two or more of the above-mentioned substances, there is no particular requirement on the material proportioning ratio of the specific substance in the present invention. In the present invention, the inorganic base is preferably used in the form of an inorganic base solution, the solvent of the inorganic base solution is preferably water, and in the present invention, the inorganic base solution is preferably contained in an amount of 10% by mass.

In the invention, the molar ratio of the 2, 6-dibromocyclohexanone to the inorganic base is preferably 1 (1-3), and more preferably 1 (1.5-2.5).

In the present invention, the polar solvent used for the hydrolysis reaction preferably includes one or more of methyl chloride, lower alcohol, acetonitrile, tetrahydrofuran, benzene, nitromethane, toluene and water, the methyl chloride preferably includes methylene chloride and/or chloroform, and the lower alcohol preferably includes methanol and/or ethanol, and in the present invention, the polar solvent more preferably includes one or more of methylene chloride, chloroform, methanol, ethanol, acetonitrile, tetrahydrofuran, benzene, nitromethane, toluene and water, and most preferably one or more of chloroform, ethanol, acetonitrile, tetrahydrofuran, benzene, nitromethane, toluene and water.

In the invention, the molar ratio of the 2, 6-dibromocyclohexanone to the polar solvent is preferably 1 (1-3), and more preferably 1 (2-2.5).

In the present invention, the second mixing is preferably: mixing the 2, 6-dibromocyclohexanone and a polar solvent, and then mixing with the inorganic base.

In the invention, the temperature of the hydrolysis reaction is preferably 20-40 ℃, more preferably 21-23 ℃, the time of the hydrolysis reaction is preferably 2-3 h, the hydrolysis reaction is preferably carried out under the condition of stirring, and the specific implementation process of the stirring is not specially required.

In the present invention, it is preferable that the system after the hydrolysis reaction is subjected to a post-treatment to obtain the 1, 2-cyclohexanedione, and in the present invention, the post-treatment preferably includes: sequentially adjusting the pH value of a reactant to 6-7, extracting, dehydrating an extract phase, removing an extractant, and recrystallizing a solid product; in the invention, the pH reagent used for adjusting the pH value of the reactant is preferably a hydrochloric acid solution, and the invention has no special requirement on the mass concentration of the hydrochloric acid solution. In the invention, the extracting agent for extraction is preferably ethyl acetate, the volume ratio of the extracting agent to the hydrolysis reaction liquid after the pH value is adjusted is preferably 1:1, and the invention preferably extracts the target product 1, 2-cyclohexanedione into the extracting agent phase through extraction. According to the invention, the extraction phase is preferably dehydrated by adopting a solid dehydrating agent, the solid dehydrating agent is preferably anhydrous sodium sulfate, and the solid-liquid ratio of the solid dehydrating agent to the extraction phase is preferably 0.25: 1. The method preferably comprises the step of removing the extracting agent by rotary evaporation to obtain a solid product, wherein the rotary evaporation temperature is preferably 38-45 ℃, and the method has no special requirement on the rotary evaporation time so as to remove the extracting agent completely. According to the invention, the obtained solid product is preferably recrystallized to obtain the 1, 2-cyclohexanedione. In the invention, the solvent for recrystallization is preferably a mixed solvent of ethyl acetate and petroleum ether, the volume ratio of the ethyl acetate to the petroleum ether is preferably 1:2, the solid ratio of the solid product to the mixed solvent is 1:0.25, and the invention has no special requirements on the specific implementation process of recrystallization.

The target product 1, 2-cyclohexanedione is preferably monitored in the examples of the invention using gas phase and nuclear magnetism.

The technical solution of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. It is to be understood that the described embodiments are merely exemplary of the invention, and not restrictive of the full scope of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

Example 1

The reaction is carried out according to the equation shown in formula I:

10g of cyclohexanone, 3.0g of ammonium carbonate, 53.0g of NBS (N-bromosuccinimide) were dissolved in 150mL of CHCl₃Stirring and reacting for 2 hours at the temperature of 40 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 1, 2-dibromocyclohexanone is 76.7 percent (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 97.6 percent.

Dissolving 60g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 35g of 2, 6-dibromocyclohexanone into 50mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 1h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 72% (calculated on the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 99.3%.

Fig. 1 is a nuclear magnetic spectrum of the 1, 2-cyclohexanedione prepared in this example, and it can be seen from fig. 1 that the 1, 2-cyclohexanedione product is prepared in example 1 of the present invention, the preparation method provided by the present invention is reliable, the raw materials are simple and easy to obtain, and the prepared 1, 2-cyclohexanedione product has high purity and yield, and is suitable for industrial production.

Fig. 2 is a gas chromatogram of 1, 2-cyclohexanedione prepared in this example, and it can be seen from fig. 2 that the 1, 2-cyclohexanedione product prepared in example 1 of the present invention has substantially no other miscellaneous peak except for the solvent peak, which indicates that the preparation method provided by the present invention is reliable and the prepared product has high purity.

Example 2

The reaction was carried out according to the equation shown in formula II:

dissolving 12g of cyclohexanone, 3.4g of potassium carbonate and 55.0g of NBS (N-bromosuccinimide) in 180mL of petroleum ether, and stirring for reaction at 35 ℃ for 2.5 hours; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 1, 2-dibromocyclohexanone is 74% (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 96%.

Dissolving 80g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 37g of 2, 6-dibromocyclohexanone into 60mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 2h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 74.1% (calculated by the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 98%.

Example 3

The reaction was carried out according to the equation shown in formula III:

dissolving 15g of cyclohexanone, 4.0g of potassium carbonate and 60.0g of liquid bromine in 200mL of isopropyl ether, and stirring and reacting for 3 hours at the temperature of 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 1, 2-dibromocyclohexanone is 75.6 percent (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 98 percent.

Dissolving 80g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 40g of 1, 2-dibromocyclohexanone into 70mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 1.5h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 74.9% (calculated according to the mass of the 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 97.5%.

Example 4

The reaction was carried out according to the equation shown in formula IV:

8g of cyclohexanone, 2.5g of potassium carbonate and 30.0g of DBI (dibromoisocyanuric acid) are dissolved in 100mL of trichloromethane, and are stirred and reacted for 3 hours at the temperature of 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 2, 6-dibromocyclohexanone is 73 percent (calculated by the mass of the cyclohexanone), and the purity of the 1, 2-dibromocyclohexanone is detected by GC and is 97.5 percent.

Dissolving 60g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 25g of 1, 2-dibromocyclohexanone into 50mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 1h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 72% (calculated on the mass of the 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 97.9%.

Example 5

The reaction is carried out according to the equation shown in formula V:

10g of cyclohexanone, 3.0g of potassium carbonate and 35.0g of 35.0g N-bromoacetamide are dissolved in 100mL of trichloromethane, and the mixture is stirred and reacted for 2 hours at the temperature of 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 2, 6-dibromocyclohexanone is 78% (calculated by the mass of the cyclohexanone), and the purity of the 1, 2-dibromocyclohexanone is detected by adopting GC to show that the purity is 97%.

Dissolving 70g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 35g of 2, 6-dibromocyclohexanone into 60mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 2h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 71.3% (calculated according to the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 96.9%.

Example 6

The reaction is carried out according to the equation shown in formula VI:

5g of cyclohexanone, 1.0g of ammonium carbonate and 25.0g of phenyltrimethyl ammonium tribromide are dissolved in 150mL of trichloromethane, and stirred and reacted for 2 hours at the temperature of 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 2, 6-dibromocyclohexanone is 78.7 percent (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 98.6 percent.

Dissolving 30g of NaOH in 250mL of water to obtain a sodium hydroxide solution, adding 15g of 2, 6-dibromocyclohexanone into 25mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 1h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 77% (calculated based on the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 98.3%.

Example 7

The reaction was carried out according to the equation shown in formula VII:

dissolving 11g of cyclohexanone, 3.3g of potassium carbonate and 25.0g of benzyl ammonium tribromide in 160mL of petroleum ether, and stirring for reaction for 2.5 hours at 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 2, 6-dibromocyclohexanone is 74.7 percent (calculated by the mass of the cyclohexanone), and the purity of the 1, 2-dibromocyclohexanone is detected by adopting GC to show that the purity is 97 percent.

Dissolving 70g of NaOH in 300mL of water to obtain a sodium hydroxide solution, adding 32g of 2, 6-dibromocyclohexanone into 60mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 2h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 77% (calculated based on the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 95%.

Example 8

The reaction is carried out according to the equation shown in formula VIII:

dissolving 30g of cyclohexanone, 6g of potassium carbonate and 80.0g of benzyl ammonium tribromide in 400mL of acetonitrile, and stirring for reaction for 3 hours at 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 1, 2-dibromocyclohexanone, wherein the yield of the 1, 2-dibromocyclohexanone is 72.6 percent (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 93.6 percent.

Dissolving 95g of NaOH in 600mL of water to obtain a sodium hydroxide solution, adding 60g of 2, 6-dibromocyclohexanone into 90mL of tetrahydrofuran, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 5h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 72.9% (calculated according to the mass of 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 96.5%.

Example 9

The reaction was carried out according to the equation shown in formula IX:

dissolving 10g of cyclohexanone, 3.0g of potassium carbonate and 53.0g of liquid bromine in 150mL of trichloromethane, and stirring for reaction for 3 hours at the temperature of 25 ℃; filtering, removing filter residues, collecting filtrate, adding ethyl acetate for extraction, removing the ethyl acetate in an extraction phase by adopting rotary evaporation to obtain the 2, 6-dibromocyclohexanone, wherein the yield of the 2, 6-dibromocyclohexanone is 74.7 percent (calculated by the mass of the cyclohexanone), and the purity of the 2, 6-dibromocyclohexanone is detected by adopting GC to show that the purity is 95 percent.

Dissolving 60g of NaOH in 500mL of water to obtain a sodium hydroxide solution, adding 35g of 2, 6-dibromocyclohexanone into 50mL of trichloromethane, mixing, adding the sodium hydroxide solution, mixing, stirring and hydrolyzing at 20 ℃, reacting for 1h, adjusting the pH value of the reaction system solution to 6-7 with hydrochloric acid, extracting with ethyl acetate, dehydrating with anhydrous sodium sulfate, removing the ethyl acetate by rotary evaporation to obtain a solid product, recrystallizing the solid product with ethyl acetate and petroleum ether (volume ratio of 1:2) to obtain cyclohexanedione, wherein the yield of the cyclohexanedione is 72% (calculated on the mass of the 2, 6-dibromocyclohexanone), and GC detection shows that the purity of the cyclohexanedione is 93%.

Comparative example 1

The experimental procedure was carried out according to the method provided in patent CN108840790 a: 0.98g of cyclohexanone is added into a round-bottom flask, then 10mL of mixed solvent of tetrahydrofuran and water is prepared (the volume ratio of the tetrahydrofuran to the water is 1:5), the mixed solvent is added into the cyclohexanone, 0.25g of iodine is added, the mixture is heated to 25 ℃ for reaction for 2h, TCL monitors the reaction progress, and the 1, 2-cyclohexanedione is obtained by reduced pressure distillation, wherein the yield is 27 percent (calculated by the mass of the cyclohexanone).

Comparative example 2

The experimental procedure was carried out according to the method provided in patent CN108840790 a: 1.18g of cyclohexanone is added into a round-bottom flask, then 10mL of mixed solvent of acetonitrile and water is prepared (the volume ratio of the acetonitrile to the water is 1:5), the mixed solvent is added into the cyclohexanone, 0.15g of iodine is added, the mixture is heated to 40 ℃ to react for 2h, TCL monitors the reaction progress, and the 1, 2-cyclohexanedione is obtained by reduced pressure distillation, wherein the yield is 15 percent (calculated by the mass of the cyclohexanone).

Comparative example 3

The experimental procedure was carried out according to the method provided in patent CN108840790 a: 1.57g of cyclohexanone is added into a round-bottom flask, then 10mL of mixed solvent of tetrahydrofuran and water is prepared (the volume ratio of the tetrahydrofuran to the water is 1:5), the mixed solvent is added into the cyclohexanone, 0.32g of iodine is added, the mixture is heated to 60 ℃ to react for 2h, TCL monitors the reaction progress, and the 1, 2-cyclohexanedione is obtained by reduced pressure distillation, wherein the yield is 23 percent (calculated by the mass of the cyclohexanone).

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various modifications and decorations can be made without departing from the principle of the present invention, and these modifications and decorations should also be regarded as the protection scope of the present invention.