A kind of preparation method of 2-isopropylidene-5-methylcyclohexanone
By using homemade copper-based catalysts in a fixed bed reactor for catalytic dehydrogenation rearrangement reaction, the problems of expensive catalysts and wastewater generation in the prior art were solved, and 2-isopropylene-5-methylcyclohexanone were achieved Efficient and environmentally friendly preparation.
Patent Information
- Application Number
- CN202310400302.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- Filing Date
- 2023-04-14
- Publication Date
- 2024-12-17
- Estimated Expiration
- 2043-04-14
AI Technical Summary
The existing preparation method for 2-isopropylene-5-methylcyclohexanone has the problems of expensive catalysts, long reaction steps, and large amounts of salt-containing wastewater, and it is difficult to achieve continuous production.
Using isomentol as raw material, 2-isopropylene-5-methylcyclohexanone, copper-based The catalyst is prepared by stirring ammonia water and copper nitrate solution, adding silica sol, calcining and mixing γ-alumina, avoiding the use of solvents and heavy metal catalysts.
It realizes the preparation process of simple operation, continuous reaction, solvent-free and heavy metal oxidant-free, reducing the generation of wastewater and waste salt and improving production efficiency.
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Abstract
Description
Technical Field
[0001] The invention belongs to the technical field of organic synthesis, relates to the synthesis of a perfume and a pharmaceutical intermediate, and particularly relates to a preparation method of 2-isopropylidene-5-methylcyclohexanone. Background Art
[0002] 2-Isopropylidene-5-methylcyclohexanone has a mint-like aroma and exists naturally in Nepeta paniculata and Nepeta tenuifolia. It is one of the important representatives of monocyclic terpenes and has anti-inflammatory, antiviral and analgesic effects. It can be used to prepare flavors such as mint, lavender, and rose, and can also be used in the pharmaceutical, food and cosmetic industries.
[0003] Foreign literature J.Org.Chem, 1976, 41(2):380 reported that citronellal was used as a raw material and 2-isopropylidene-5-methylcyclohexanone was prepared by oxidation cyclization with pyridinium chlorochromate. The chromium catalyst in this method is highly toxic, the preparation process is complicated, dichloromethane is used as a solvent, and a large amount of saline wastewater is produced. Foreign literature Tetrahedron Letters, 1981, 22(19):1801 reported that isopulegol was used as a raw material, and 2-isopropylidene-5-methylcyclohexanone was prepared by catalytic oxidation isomerization under the conditions of palladium catalyst, oxidant, sodium hydride and tetrahydrofuran as solvent. The palladium catalyst in this method is expensive and a large amount of saline wastewater is also produced. Chinese literature Zhang Hesheng. Synthesis of pulegone and linalool from citral. Journal of Hubei University (Natural Science Edition), 1992 (14): 4 reported the preparation of 2-isopropylidene-5-methylcyclohexanone using isopulegol as raw material, acetonitrile as solvent, and 5% sodium hypochlorite solution as oxidant. The amount of solvent used in this method is more than 6 times that of the raw material, and a large amount of chlorine-containing wastewater is produced. US Patent US20060160719 reported the preparation of 2-isopropylidene-5-methylcyclohexanone using isopulegol as raw material and copper-zinc-aluminum composite catalyst as catalyst. This method adopts intermittent reactor reaction and cannot be continuously produced, and the catalyst cannot be reused. Summary of the invention
[0004] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for preparing 2-isopropylidene-5-methylcyclohexanone. The method has simple steps, can be produced continuously, does not use solvents, does not use heavy metal catalysts, and is environmentally friendly.
[0005] The present invention is achieved through the following technical solutions:
[0006] A method for preparing 2-isopropylidene-5-methylcyclohexanone comprises the following steps:
[0007] With isopulegol as raw material, a fixed bed as a reactor and nitrogen as a carrier gas, 2-isopropylidene-5-methylcyclohexanone is prepared by catalytic dehydrogenation rearrangement reaction under the action of a copper-based catalyst.
[0008] A further improvement of the present invention is:
[0009] The copper-based catalyst is prepared by the following steps: stirring and mixing an ammonia solution and a copper nitrate solution to obtain a copper-ammonia solution; dropping silica sol into the copper-ammonia solution until the pH value of the solution is 11-12, and stirring to form a suspension; evaporating ammonia from the suspension until it becomes a paste, washing with distilled water, drying, grinding, and then calcining in a muffle furnace, mixing with γ-alumina after calcination and grinding evenly, tableting with a tablet press, and sieving to 40-100 mesh to obtain the copper-based catalyst.
[0010] Furthermore, during the calcination, the temperature is raised to 400-600° C. at a rate of 2° C. / min and the calcination is performed for 3-6 hours.
[0011] Preferably, the calcination temperature is 450° C. and the calcination time is 4 hours.
[0012] Furthermore, in the copper-based catalyst, the mass percentage of copper is 10-50% calculated as copper oxide.
[0013] Preferably, in the copper-based catalyst, the mass percentage of copper is 20-30% calculated as copper oxide.
[0014] Furthermore, the reaction temperature is 200-300°C.
[0015] Preferably, the reaction temperature is 260-280°C.
[0016] Compared with the prior art, the present invention has the following beneficial effects:
[0017] The invention uses isopulegol as a raw material, a fixed bed as a reactor, nitrogen as a carrier gas, and performs a catalytic dehydrogenation rearrangement reaction under the action of a homemade copper-based catalyst to prepare 2-isopropylidene-5-methylcyclohexanone.
[0018] The invention solves the problems of long reaction steps, expensive catalysts and large amount of wastewater and waste salt in the preparation process of 2-isopropylidene-5-methylcyclohexanone, and has the advantages of simple operation, continuous reaction, no heavy metal oxidant and no solvent. DETAILED DESCRIPTION
[0019] The present invention is described in detail below in conjunction with specific embodiments.
[0020] Example 1: Preparation of a copper-based catalyst containing 20% to 30% copper (calculated as copper oxide) by mass
[0021] Take 16g-27g of copper nitrate trihydrate and add 700g-800g of double distilled water to prepare a solution. Under stirring, slowly add 25% ammonia solution dropwise to the copper nitrate solution until the pH value of the solution is 10-12. Stir vigorously for 1 hour to obtain a copper ammonia solution. Weigh 84g of silica sol (silicon dioxide mass fraction 25%), slowly add dropwise to the above copper ammonia solution until the pH value of the solution is 11-12, and stir vigorously for 7 hours to turn the solution into a suspension. The above suspension is subjected to ammonia evaporation in a 90°C water bath until it becomes a paste. Wash the above sample three times with 800g of double distilled water, dry and grind at 120°C, place it in a muffle furnace, heat it to 450°C at a heating rate of 2°C / min, and roast it for 4h. The obtained catalyst is mixed with γ-alumina at a mass ratio of 2:1 and ground evenly, pressed by a tablet press, and sieved to 40-100 mesh to obtain a homemade copper-based catalyst.
[0022] Example 2
[0023] The catalytic dehydrogenation rearrangement experiment of isopulegol was carried out in a stainless steel tube reactor with an inner diameter of 14 mm. The catalyst was a homemade copper-based catalyst with a loading amount of 50 g. Before the reaction, a mixed gas of H2 / N2=1 / 19 was introduced at 300 ml / min and the temperature was raised to 250°C and maintained for 2 hours. The flow rate of isopulegol was 0.8 g / min, the nitrogen flow rate was 300 ml / min, and the reaction temperature was 260°C. Before the reaction, isopulegol was preheated in a preheating furnace at 200°C before entering the reactor. After the reaction, gas chromatography was used for qualitative and quantitative analysis of the product. The reaction results are shown in Table 1
[0024] Example 3
[0025] The catalytic dehydrogenation rearrangement experiment of isopulegol was carried out in a stainless steel tube reactor with an inner diameter of 14 mm. The catalyst was a homemade copper-based catalyst with a loading amount of 50 g. Before the reaction, a mixed gas of H2 / N2=1 / 19 was introduced at 300 ml / min and heated to 250°C for 2 hours. The isopulegol flow rate was 0.8 g / min, the nitrogen flow rate was 300 ml / min, and the reaction temperature was 270°C. Before the reaction, isopulegol was preheated in a preheating furnace at 200°C before entering the reactor. After the reaction, gas chromatography was used for qualitative and quantitative analysis of the product. The reaction results are shown in Table 1.
[0026] Example 4
[0027] The catalytic dehydrogenation rearrangement experiment of isopulegol was carried out in a stainless steel tube reactor with an inner diameter of 14 mm. The catalyst was a homemade copper-based catalyst with a loading amount of 50 g. Before the reaction, a mixed gas of H2 / N2=1 / 19 was introduced at 300 ml / min and heated to 250°C for 2 hours. The isopulegol flow rate was 0.8 g / min, the nitrogen flow rate was 300 ml / min, and the reaction temperature was 280°C. Before the reaction, isopulegol was preheated in a preheating furnace at 200°C before entering the reactor. After the reaction, gas chromatography was used for qualitative and quantitative analysis of the product. The reaction results are shown in Table 1.
[0028] Example 5
[0029] The catalytic dehydrogenation rearrangement experiment of isopulegol was carried out in a stainless steel tube reactor with an inner diameter of 14 mm. The catalyst was a homemade copper-based catalyst with a loading amount of 50 g. Before the reaction, a mixed gas of H2 / N2=1 / 19 was introduced at 300 ml / min and heated to 250°C for 2 hours. The isopulegol flow rate was 1.2 g / min, the nitrogen flow rate was 300 ml / min, and the reaction temperature was 270°C. Before the reaction, isopulegol was preheated in a preheating furnace at 200°C before entering the reactor. After the reaction, gas chromatography was used for qualitative and quantitative analysis of the product. The reaction results are shown in Table 1.
[0030] Example 6
[0031] The catalytic dehydrogenation rearrangement experiment of isopulegol was carried out in a stainless steel tube reactor with an inner diameter of 14 mm. The catalyst was a homemade copper-based catalyst with a loading amount of 50 g. Before the reaction, a mixed gas of H2 / N2=1 / 19 was introduced at 300 ml / min and heated to 250°C for 2 hours. The isopulegol flow rate was 1.5 g / min, the nitrogen flow rate was 300 ml / min, and the reaction temperature was 270°C. Before the reaction, isopulegol was preheated in a preheating furnace at 200°C before entering the reactor. After the reaction, gas chromatography was used for qualitative and quantitative analysis of the product. The reaction results are shown in Table 1.
[0032] Table 1 Reaction results of Examples 2-6
[0033]
[0034] The above embodiments are only for illustrating the technical concept and features of the present invention, and their purpose is to enable people familiar with the technology to understand the content of the present invention and implement it accordingly, and they cannot be used to limit the protection scope of the present invention. Any equivalent transformation or modification made according to the spirit of the present invention should be included in the protection scope of the present invention.
Claims
1. A method for preparing 2-isopropylidene-5-methylcyclohexanone, It is characterized in that The following steps are involved: Using isopulegol as raw material, a fixed bed as a reactor, nitrogen as a carrier gas, and a copper-based catalyst, a catalytic dehydrogenation rearrangement reaction is carried out to prepare 2-isopropylidene-5-methylcyclohexanone; The copper-based catalyst is prepared by the following steps: stirring and mixing an ammonia solution and a copper nitrate solution to obtain a copper-ammonia solution; dropping silica sol into the copper-ammonia solution until the pH value of the solution is 11-12, and stirring to form a suspension; evaporating ammonia from the suspension until it becomes a paste, washing with distilled water, drying, grinding, and then calcining in a muffle furnace, mixing with γ-alumina after calcination and grinding evenly, tabletting with a tablet press, and sieving to 40-100 mesh to obtain the copper-based catalyst; In the copper-based catalyst, the mass percentage of copper is 20-30% calculated as copper oxide.
2. A method for preparing 2-isopropylidene-5-methylcyclohexanone according to claim 1, Features: During the calcination, the temperature is raised to 400-600° C. at a rate of 2° C. / min and the calcination is performed for 3-6 hours.
3. A method for preparing 2-isopropylidene-5-methylcyclohexanone according to claim 2, Features: The calcination temperature is 450° C. and the calcination time is 4 hours.
4. A method for preparing 2-isopropylidene-5-methylcyclohexanone according to claim 1, Features: The reaction temperature is 200-300°C.
5. A method for preparing 2-isopropylidene-5-methylcyclohexanone according to claim 4, Features: The reaction temperature is 260-280°C.