A process for the catalytic oxidation of ethylbenzene to acetophenone
By using a nitrogen-containing porphyrin-based metal complex catalyst, acetophenone was prepared from ethylbenzene under mild conditions with air as the oxidant. This solved the problems of high cost and high pressure in the existing technology, and achieved efficient, green, and selective preparation of acetophenone.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HUIZHOU RES INST OF SUN YAT SEN UNIV
- Filing Date
- 2023-11-10
- Publication Date
- 2026-06-05
AI Technical Summary
Existing methods for synthesizing acetophenone suffer from high costs, high catalyst consumption, and the need for high temperatures and pressures or the use of environmentally unfriendly oxidants, making it difficult to achieve a mild, simple, and efficient selective oxidation of ethylbenzene to prepare acetophenone.
A nitrogen-containing porphyrin-like metal complex was used as a catalyst, with air as the oxidant, to catalyze the oxidation of ethylbenzene to prepare acetophenone at 30-100℃ and 0.5-3.0 MPa. Acetonitrile, ethyl acetate, sec-butyl acetate, dichloroethane, dichloromethane, or trifluorotoluene were used as solvents, and the catalyst dosage was 0.05-0.3 mol.
It achieves green and safe processes, high raw material conversion rates, good product selectivity, low catalyst dosage, mild reaction conditions, and simple processes.
Smart Images
Figure CN117623887B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to a method for preparing acetophenone, specifically a method for preparing acetophenone by catalytic oxidation of ethylbenzene using a metal complex with a nitrogen-containing porphyrin structure. Background Technology
[0002] Acetophenone is one of the most important representative aromatic ketones in the aromatic compound family, and it is widely used in food, pesticides, biology, and medicine. At the same time, acetophenone is also commonly used as a solvent, possessing characteristics such as a high boiling point and excellent stability, and can dissolve many poorly soluble substances.
[0003] Currently, the main methods for synthesizing acetophenone include Friedel-Crafts acylation and direct oxidation of ethylbenzene. The Friedel-Crafts acylation method for preparing acetophenone has been gradually phased out due to its high cost, large catalyst consumption, and high heat release. Direct oxidation of acetophenone with ethylbenzene has attracted increasing attention due to the cheap and readily available raw materials. However, the inertness of the CH bond on the aromatic side chain means that activation oxidation usually requires high temperature and high pressure conditions, or the use of strong oxidants such as peroxy acids, which have a significant environmental impact.
[0004] Currently, some relatively mild catalytic systems for the oxidation of ethylbenzene have been reported. For example, Chinese patent (CN113813993 A) discloses a method for the selective oxidation of ethylbenzene to acetophenone using an Ag2C2O4 / Ag2O composite catalyst, which yields acetophenone in 60% yield after 24 hours of reaction at 120°C. Meanwhile, Chinese patent (CN115403455 A) discloses a method for preparing acetophenone using ozone as an oxidant and N-hydroxyphthalimide (NHPI) as a free radical initiator. This method requires ozone and the addition of 15 wt% NHPI as a free radical initiator.
[0005] Therefore, developing a process for preparing acetophenone that uses ethylbenzene as a raw material, air as an oxidant, and is characterized by mild conditions, simple process, high efficiency, and high selectivity will have very important application prospects. Summary of the Invention
[0006] The purpose of this invention is to overcome the shortcomings of the prior art and provide a method for the selective oxidation of ethylbenzene to prepare acetophenone that is mild, simple, and highly efficient.
[0007] To achieve the objectives of this invention, the technical solution adopted is: a method for preparing acetophenone by catalytic oxidation of ethylbenzene, using ethylbenzene as a raw material, air as an oxidant, a compound having the general formula (I) as a catalyst, adding an organic solvent, controlling the reaction temperature at 30-100℃, the reaction pressure at 0.5-3.0 MPa, and adding a catalyst at an amount of 0.05-0.3 mol% of the raw material to carry out the catalytic reaction to obtain acetophenone.
[0008]
[0009] In general formula (I), M is a metal selected from Co, Mn, Cu, Zn, Mg, and Ni, and R1 and R2 are selected from hydrogen, halogen, nitro, alkyl, alkoxy, or hydroxyl.
[0010] In the above method for preparing acetophenone, the catalyst is preferably one of the metals in general formula (I), namely Co, Cu, and Ni, and R1 and R2 are selected from halogen, nitro, and alkoxy groups.
[0011] In the above method for preparing acetophenone, the organic solvent is selected from acetonitrile, ethyl acetate, sec-butyl acetate, dichloroethane, dichloromethane, and trifluorotoluene.
[0012] In the above method for preparing acetophenone, the amount of catalyst used is 0.1-0.2 mol% of the raw material, the reaction temperature is 50-80℃, and the reaction pressure is 1.0-2.5 MPa.
[0013] The present invention has the following beneficial effects:
[0014] 1. The process of this invention uses air as an oxidant, making the process green and safe.
[0015] 2. This invention does not require the addition of free radical initiators or other auxiliaries, resulting in high raw material conversion rate and good product selectivity.
[0016] 3. The catalytic system of the present invention has mild reaction conditions, simple process, and low catalyst dosage. Attached Figure Description
[0017] Figure 1 The 1H NMR spectrum of acetophenone obtained in Example 1 (…) 1 HNMR). Detailed Implementation
[0018] The present invention will be further described below with reference to the embodiments, but the present invention is not limited to these embodiments.
[0019] Example 1
[0020] In a high-pressure reactor containing 10 mL of acetonitrile solution, 5.0 mmol of ethylbenzene and 0.3 mol% of a catalyst with general formula (I) (M = Co, R1 = H, R2 = OH) were added. The reactor was then purged with air at 3.0 MPa and stirred at 30 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 90%, and the selectivity of the product acetophenone was 96%. The 1H NMR spectrum of the obtained product is shown below. Figure 1 As shown, the obtained product is the target product, acetophenone.
[0021] Example 2
[0022] In a high-pressure reactor containing 10 mL of ethyl acetate solution, 5.0 mmol of ethylbenzene and 0.05 mol% of a catalyst with general formula (I) (M = Mn, R1 = Cl, R2 = OCH3) were added. The reactor was purged with 0.5 MPa of air and stirred at 100 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 91% and the selectivity of the product acetophenone was 97%.
[0023] Example 3
[0024] In a high-pressure reactor containing 10 mL of sec-butyl acetate solution, 5.0 mmol of ethylbenzene and 0.1 mol% of a catalyst with general formula (I) (M = Cu, R1 = CH3, R2 = OCH3) were added. The reactor was then purged with 1.0 MPa of air and stirred at 80 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 95% and the selectivity of the product acetophenone was 98%.
[0025] Example 4
[0026] In a high-pressure reactor containing 10 mL of dichloroethane solution, 5.0 mmol of ethylbenzene and 0.2 mol% of a catalyst with general formula (I) (M = Zn, R1 = F, R2 = CH3) were added. The reactor was then purged with 2.5 MPa of air and stirred at 60 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 92% and the selectivity of the product acetophenone was 96%.
[0027] Example 5
[0028] In a high-pressure reactor containing 10 mL of dichloromethane solution, 5.0 mmol of ethylbenzene and 0.15 mol% of a catalyst with general formula (I) (M = Mg, R1 = OCH3, R2 = NO2) were added. The reactor was then purged with 2.0 MPa of air and stirred at 70 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 92% and the selectivity of the product acetophenone was 93%.
[0029] Example 6
[0030] In a high-pressure reactor containing 10 mL of trifluorotoluene solution, 5.0 mmol of ethylbenzene and 0.1 mol% of a catalyst with general formula (I) (M = Ni, R1 = Cl, R2 = NO2) were added. The reactor was then purged with 2.0 MPa of air and stirred at 80 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 98% and the selectivity of the product acetophenone was 97%.
[0031] Example 7
[0032] In a high-pressure reactor containing 10 mL of sec-butyl acetate solution, 5.0 mmol of ethylbenzene and 0.2 mol% of a catalyst with general formula (I) (M = Cu, R1 = OH, R2 = F) were added. The reactor was then purged with 1.5 MPa of air and stirred at 50 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 99% and the selectivity of the product acetophenone was 99%.
[0033] Example 8
[0034] In a high-pressure reactor containing 10 mL of dichloromethane solution, 5.0 mmol of ethylbenzene and 0.1 mol% of a catalyst with general formula (I) (M = Co, R1 = OCH3, R2 = NO2) were added. The reactor was then purged with 2.0 MPa of air and stirred at 60 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 98% and the selectivity of the product acetophenone was 99%.
[0035] Example 9
[0036] In a high-pressure reactor containing 10 mL of trifluorotoluene solution, 5.0 mmol of ethylbenzene and 0.2 mol% of a catalyst with general formula (I) (M = Ni, R1 = NO2, R2 = OCH3) were added. The reactor was then purged with 1.0 MPa of air and stirred at 70 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 98.0% and the selectivity of the product acetophenone was 98%.
[0037] Example 10
[0038] In a high-pressure reactor containing 10 mL of ethyl acetate solution, 5.0 mmol of ethylbenzene and 0.1 mol% of a catalyst with general formula (I) (M = Cu, R1 = Cl, R2 = OCH3) were added. The reactor was then purged with air at 2.5 MPa and stirred at 80 °C. After 4 h, gas chromatography analysis showed that the conversion rate of ethylbenzene was 98% and the selectivity of the product acetophenone was 99%.
Claims
1. A method for preparing acetophenone by catalytic oxidation of ethylbenzene, characterized in that... Acetophenone was obtained by using ethylbenzene as a raw material, air as an oxidant, a compound with the general formula (I) as a catalyst, an organic solvent, and controlling the reaction temperature at 30-100℃ and the reaction pressure at 0.5-3.0 MPa. A catalyst at 0.05-0.3 mol% of the raw material was added to carry out the catalytic reaction. In general formula (I), M is a metal selected from Co, Mn, Cu, Zn, Mg, and Ni, and R1 and R2 are selected from hydrogen, halogen, nitro, alkyl, alkoxy, or hydroxyl.
2. The method according to claim 1, characterized in that... The metal in the general formula (I) is selected from Co, Cu, and Ni.
3. The method according to claim 1, characterized in that... In the general formula (I), R1 and R2 are selected from halogen, nitro, and alkoxy groups.
4. The method according to claim 1, characterized in that... The organic solvent is selected from acetonitrile, ethyl acetate, sec-butyl acetate, dichloroethane, dichloromethane, and trifluorotoluene.
5. The method according to claim 1, characterized in that... The catalyst dosage is 0.1-0.2 mol% of the raw material.
6. The method according to claim 1, characterized in that... The temperature of the catalytic reaction is 50-80℃.
7. The method according to claim 1, characterized in that... The pressure of the catalytic reaction is 1.0-2.5 MPa.