A green preparation method suitable for industrial production of 1,3-cyclohexanedione

Abstract

The invention discloses a green preparation method suitable for industrial production of 1,3-cyclohexanedione. Resorcinol and liquid alkali are reacted to obtain monosodium resorcinol, and catalytic hydrogenation is performed to obtain sodium enolate reaction liquid. The catalyst is filtered to remove the catalyst, and the filtrate is acidified and centrifuged to obtain a 1,3-cyclohexanedione wet product and an acidified mother liquor. The wet product is dried to obtain a 1,3-cyclohexanedione finished product. The acidified mother liquor is extracted with an organic solvent, and the 1,3-cyclohexanedione in the acidified mother liquor is stripped into a water phase. The stripped water phase is used as washing water to wash a reactor and a catalyst of a next batch reaction, and the cyclohexanedione is precipitated in the acid adjustment process of the next batch reaction, thereby improving the yield, avoiding the production of products of two specifications of a primary material and a mother liquor material, and simplifying the production. The 1,3-cyclohexanedione prepared by the method has good purity and high yield. In a single reaction of washing the reactor and the catalyst with the stripped water phase, the yield of the obtained cyclohexanedione is not less than 94%, and the purity is not less than 99%. The method is green and environmentally friendly and suitable for industrial production.

Description

Technical Field

[0001] The invention belongs to the field of fine chemicals, and in particular relates to a green preparation method suitable for industrial production of 1,3-cyclohexanedione. Background Art

[0002] 1,3-cyclohexanedione has an active β-dicarbonyl structure and is widely used in organic synthesis. It is an important chemical intermediate. It can be used to synthesize carvedilol, a special drug for protecting cardiovascular and cerebrovascular vessels and treating hypertension, and ondansetron, an antiemetic drug. In addition, it is also an important intermediate for synthesizing cosmetics, polymer additives, and excellent herbicides mesotrione and sulcotrione.

[0003] 1,3-cyclohexanedione can be produced by catalytic hydrogenation of resorcinol. At present, the mainstream production method of 1,3-cyclohexanedione is to hydrogenate resorcinol in an alkaline solution under the action of a transition metal catalyst and then acidify it. The catalytic hydrogenation method for producing 1,3-cyclohexanedione has the advantages of high product yield, easy reaction control, and easy product separation.

[0004] Nickel-based catalysts are currently the most commonly used catalysts in the preparation of 1,3-cyclohexanedione by catalytic hydrogenation of resorcinol in industry because of their commercially available large-scale stable supply, repeatable application, and low price. The synthesis route is as follows:

[0005]

[0006] In the catalytic hydrogenation process of cyclohexanedione, the steps of salt formation, hydrogenation, acidification, centrifugation and drying are relatively conventional operations with low technical requirements. Since cyclohexanedione has good water solubility, a large amount of product residues remain in the centrifuged mother liquor. In addition, cyclohexanedione is thermally unstable, and the product may dimerize and produce by-products during the desolvation and crystallization processes after extraction, making the product yellow, sticky and scrapped.

[0007] At present, there are few reports on the recovery of 1,3-cyclohexanedione products from acidified mother liquor at home and abroad. The more representative one is the process reported in Chinese patent application CN111302909, which uses organic amine complexing agent, organic solvent extraction, strong alkali decomplexing, acid adjustment and crystallization. However, this process has the disadvantages of complex operation, waste salt generated in the acid adjustment and alkali adjustment sections, thereby increasing the cost of environmental protection treatment, and forming two specifications of products, namely, primary acid adjustment material and mother liquor acid adjustment material, which is not conducive to unified packaging and sales. Summary of the invention

[0008] The object of the present invention is to provide a green preparation method suitable for industrial production of 1,3-cyclohexanedione. The prepared 1,3-cyclohexanedione has good purity and high yield, is green and environmentally friendly, is suitable for industrial production, and solves the problem of recovering 1,3-cyclohexanedione in acidified mother liquor in the prior art.

[0009] In order to achieve the above object, the present invention provides the following technical solutions:

[0010] A green preparation method of 1,3-cyclohexanedione comprises the following steps:

[0011] 1) Hydrogenation reaction and acidification

[0012] In the presence of water, resorcinol is reacted with liquid alkali to obtain monosodium resorcinol, followed by hydrogenation under the action of nickel, palladium or platinum catalyst to obtain a reaction solution containing sodium enolate, after the reaction is completed, the reaction solution is filtered to remove the catalyst, the reaction kettle and the catalyst are washed with deionized water, the filtrate is combined, hydrochloric acid is added to acidify to pH=2-3, 1,3-cyclohexanedione is precipitated, 1,3-cyclohexanedione wet product and acidified mother liquor are obtained by centrifugation, and cyclohexanedione finished product is obtained by drying;

[0013] The reaction formula is as follows:

[0014]

[0015] 2) Extraction and stripping

[0016] The acidified mother liquor containing 1,3-cyclohexanedione is extracted with a halogenated alkane or ether organic solvent to obtain an acidified water phase and an organic phase; the acidified water phase is subjected to desalination and biochemical degradation treatment; water is added to the organic phase three times to strip the 1,3-cyclohexanedione in the organic phase into the water phase to obtain a stripped water phase and a secondary organic phase;

[0017] 3) repeating steps 1) and 2), and washing the reactor and the catalyst with the stripping water phase obtained by stripping when filtering the reaction solution, dissolving the remaining part of the product in water, combining it with the filtrate and acidifying to precipitate;

[0018] 4) combining the secondary organic phases in step 2) and step 3), and distilling to recover the solvent.

[0019] Furthermore, in step 1), when acidification is performed, 25%-35% hydrochloric acid is used to adjust the pH to 2-3, and the temperature is controlled at 10-20°C.

[0020] Furthermore, the amount of the organic solvent used is 25-35% of the amount of the acidified mother liquor.

[0021] Preferably, in step 2), the ether solvent is selected from one or more of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran or 1,4-dioxane, 1,2-dimethoxyethane and anisole; the halogenated alkane solvent is selected from one or more of dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane and 1,1-dichloroethane.

[0022] Furthermore, in step 1 and step 3), the catalyst is a Raney nickel catalyst.

[0023] Furthermore, in step 4), a high boiling point solvent free of halogen and heteroatom is added, wherein the high boiling point solvent is a hydrocarbon solvent or an aromatic solvent having a boiling point of 90-120°C.

[0024] Preferably, in step 4), the high boiling point solvent is toluene or petroleum ether with a boiling range of 90-120°C.

[0025] Furthermore, in step 4), the still residue obtained after distillation is incinerated.

[0026] Furthermore, in a single reaction of washing the reactor and the catalyst with the stripping water phase, the yield of cyclohexanedione obtained is not less than 94% and the purity is not less than 99%.

[0027] The inventors studied the stability of cyclohexanedione and found that [M+1] + =207 impurities are cyclohexanedione dimerization products, and the process is as follows:

[0028]

[0029] After the reaction is finished, the reaction liquid is filtered, the filtrate is acidified, and the 1,3-cyclohexanedione product is separated. The acidified mother liquor is extracted with an organic solvent, and the 1,3-cyclohexanedione in the acidified mother liquor is stripped into a water phase. The stripped water phase is used as washing water to wash the reactor and the catalyst of the next batch reaction, and the product is precipitated during the acid adjustment process of the next batch reaction. The post-treatment process is controlled to be below 40° C., so that the generation of cyclohexanedione dimers is avoided, the yield of 1,3-cyclohexanedione is improved, and the generation of products of two specifications, namely, primary material and mother liquor material, is avoided.

[0030] In the present invention, after the secondary organic phases are combined, a high-boiling-point solvent free of halogens and heteroatoms is added to remove the low-boiling-point solvent in the kettle residue. The high-boiling-point solvent does not contain halogens and heteroatoms, and does not produce halogens and nitrogen oxides during incineration, so the environmental protection treatment is simple and the cost is low.

[0031] Compared with the prior art, the present invention has the following beneficial effects:

[0032] The present invention makes full use of the acidic mother liquor and extraction solvent produced in the preparation of 1,3-cyclohexanedione, re-extracts 1,3-cyclohexanedione in the acidic mother liquor into a water phase, uses the stripping water phase as washing water to wash the kettle and the catalyst, and brings part of the product of the previous batch into the next batch, and precipitates it in the next acid adjustment process, thereby improving the yield. The yield of the obtained cyclohexanedione is not less than 95%, and the purity is not less than 99%. At the same time, it avoids the production of products of two specifications, namely, the primary material and the mother liquor material, thereby simplifying the production.

[0033] In the post-treatment process of the present invention, the post-treatment process is controlled below 40° C. to avoid the generation of cyclohexanedione dimer, the generated organic phases are combined, and high-boiling point and low-boiling point solvents are obtained through distillation. The solvents can be reused, and the kettle residue is used for incineration, thereby solving the three wastes problem. DETAILED DESCRIPTION

[0034] The present invention is further described below with reference to specific embodiments and comparative examples.

[0035] Example

[0036] Hydrogenation reaction: 150 g of resorcinol (purity 99.5%, content: 99%) and liquid caustic soda (395 g, 15%) were put into a kettle to prepare a monosodium resorcinol solution, 10 g of a commercially available Raney nickel catalyst (RTH2100 type) was added, air and nitrogen were discharged according to the hydrogenation procedure, the temperature was raised to 60-65°C and the hydrogen was pressurized to 5-6 MPa, and the reaction liquid containing the sodium enolate was hydrogenated to obtain the reaction liquid, which was filtered, the reactor and the catalyst were washed with deionized water, and the filtrate was combined to obtain a hydrogenation reaction liquid.

[0037] Acidification: The hydrogenation reaction liquid was acidified to pH=2-3 with 137g (36%) hydrochloric acid to obtain an acidified mother liquor, and the temperature was controlled at 10-20°C. After the acidification was completed, the mixture was stirred for half an hour and centrifuged to obtain 136g of cyclohexanedione wet product (content: 90%, purity 99.5%) and 540g of the acidified mother liquor after centrifugation. The wet product was dried to obtain 128.2g of the first batch of finished 1,3-cyclohexanedione, purity: 99.2%, content: 95.5%, and yield: 80.7%.

[0038] Extraction and stripping: 150g of dichloromethane was added to the acidified mother liquor after centrifugation three times, stirred, separated, and combined to obtain 155g of organic phase and 520g of acidified aqueous phase. The acidified aqueous phase was desalted and biochemically degraded. 150g of deionized water was added to the organic phase obtained by extraction three times, stirred, separated, and combined to obtain 160g of stripping aqueous phase and 140g of secondary organic phase. 50g of toluene was added to the secondary organic phase, the temperature was raised, and distillation was performed on a distillation column to obtain 120g of dichloromethane, 40g of toluene, and 10g of kettle residue. Dichloromethane and toluene were used for the next extraction step, and the kettle residue was incinerated.

[0039] Hydrogenation reaction: 150 g of resorcinol and 395 g of liquid caustic soda (15%) are put into a kettle to prepare a monosodium resorcinol solution, 10 g of a commercially available Raney nickel catalyst (RTH2100) is added, air and nitrogen are discharged according to the hydrogenation procedure, the temperature is raised to 60-65°C, the reaction mixture is hydrogenated to 5-6 MPa, and the reaction mixture is filtered. The reactor and the catalyst are washed with the stripping water phase, and the filtrate is combined to obtain a hydrogenation reaction liquid.

[0040] Acidification: The hydrogenation reaction liquid was acidified to pH=2-3 with 137g (36%) hydrochloric acid to obtain an acidified mother liquor, and the temperature was controlled at 10-20°C. After the acidification was completed, the mixture was stirred for half an hour and centrifuged to obtain 160g of cyclohexanedione wet product (content: 90%, purity: 99.4%) and 675g of the acidified mother liquor after centrifugation. The wet product was dried to obtain 149.5g of the second batch of finished 1,3-cyclohexanedione, with a content of 96.0%, a purity of 99.5%, and a yield of 94.6%.

[0041] Extraction and stripping: Add 150g of dichloromethane to the acidified mother liquor after centrifugation three times, stir, separate the liquid to obtain 157g of organic phase and 655g of acidified aqueous phase, and desalt and biochemically degrade the acidified aqueous phase. Take 150g of deionized water, add it to the organic phase obtained by extraction, stir and separate the liquid to obtain 166g of stripping aqueous phase and 135g of secondary organic phase. Add 50g of toluene to the secondary organic phase, heat it up, and add a distillation column to distill to obtain 110g of dichloromethane, 35g of toluene and 12g of kettle residue. Dichloromethane and toluene are used for the next extraction step, and the kettle residue is incinerated.

[0042] The hydrogenation reaction, acidification, extraction and stripping processes are continuously repeated to obtain the 3rd to 6th batches of 1,3-cyclohexanedione.

[0043] According to the above experiment, multiple batches of experiments were carried out, and the yield data are shown in Table 1.

[0044] Table 1

[0045] batch Cyclohexanedione purity Cyclohexanedione content Yield 1 99.2％ 95.5％ 80.7％ 2 99.5％ 96.0％ 94.6％ 3 99.5％ 95.6％ 95.3％ 4 99.3％ 96.5％ 95.7％ 5 99.6％ 96.1％ 95.8％ 6 99.4％ 95.8％ 95.0％

[0046] As can be seen from Table 1, the first reaction did not recycle the mother liquor, and the yield was low, only 80.7%. The second batch of reactions increased to 94.6% due to the addition of the previous batch of recycled materials in the form of stripping water phase. The subsequent batches also had yields of about 95% due to the addition of recycled materials. After repeating 5 times, the total reaction yield can reach 92.85%, which greatly improves the yield of the cyclohexanedione preparation process, and obtains products that meet the requirements in terms of yield and quality.

Claims

1. A green preparation method suitable for industrial production of 1,3-cyclohexanedione, comprising the following steps: 1) Hydrogenation reaction and acidification In the presence of water, resorcinol is reacted with liquid alkali to obtain monosodium resorcinol, followed by hydrogenation under the action of nickel, palladium or platinum catalyst to obtain a reaction solution containing sodium enolate, after the reaction is completed, the reaction solution is filtered to remove the catalyst, the reaction kettle and the catalyst are washed with deionized water, the filtrate is combined, hydrochloric acid is added to acidify to pH=2-3, 1,3-cyclohexanedione is precipitated, 1,3-cyclohexanedione wet product and acidified mother liquor are obtained by centrifugation, and cyclohexanedione finished product is obtained by drying; The reaction formula is as follows: 2) Extraction and stripping The acidified mother liquor containing 1,3-cyclohexanedione is extracted with a halogenated alkane or ether organic solvent to obtain an acidified water phase and an organic phase; the acidified water phase is subjected to desalination and biochemical degradation treatment; water is added to the organic phase three times to strip the 1,3-cyclohexanedione in the organic phase into the water phase to obtain a stripped water phase and a secondary organic phase; 3) Repeating steps 1) and 2), and washing the reactor and the catalyst with the stripping water phase obtained by stripping when filtering the reaction solution, dissolving the remaining part of the product in water, combining it with the filtrate and acidifying to precipitate; 4) combining the secondary organic phases in step 2) and step 3), and distilling to recover the solvent; the temperature of the post-treatment process is controlled below 40°C.

2. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 1), when acidification is performed, 25%-35% hydrochloric acid is used to adjust the pH to 2-3, and the temperature is controlled at 10-20°C.

3. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 2), the amount of the organic solvent is 25-35% of the amount of the acidified mother liquor.

4. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 2), the ether organic solvent is selected from one or more of diethyl ether, ethylene glycol dimethyl ether, tetrahydrofuran or 1,4-dioxane, 1,2-dimethoxyethane and anisole; the halogenated alkane organic solvent is selected from one or more of dichloromethane, chloroform, carbon tetrachloride, 1,2-dichloroethane and 1,1-dichloroethane.

5. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 1 and step 3), the nickel catalyst is a Raney nickel catalyst.

6. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 4), a high boiling point solvent free of halogen and heteroatom is added, wherein the high boiling point solvent is a hydrocarbon solvent or an aromatic solvent having a boiling point of 90-120°C.

7. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 6, characterized in that: In step 4), the high boiling point solvent is toluene or petroleum ether with a boiling range of 90-120°C.

8. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to claim 1, characterized in that: In step 4), the still residue obtained after distillation is incinerated.

9. The green preparation method suitable for industrial production of 1,3-cyclohexanedione according to any one of claims 1 to 8, characterized in that: In a single reaction of washing the reaction kettle and the catalyst with the stripping water phase, the yield of cyclohexanedione obtained is not less than 94% and the purity is not less than 99%.

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