阅读说明：本技术 一种在分子氧存在下催化氧化环己酮制备ε-己内酯的方法 (Method for preparing epsilon-caprolactone by catalytically oxidizing cyclohexanone in presence of molecular oxygen ) 是由 孙小玲 肖锦 唐志林 贾得军 于 2021-07-07 设计创作，主要内容包括：本发明涉及一种在分子氧存在下催化氧化环己酮制备ε-己内酯的方法,以活性氧化铝负载氧化铜为催化剂,通入氧气到一定量的有机溶剂中,以环己酮为原料,加入助氧化剂,在常压条件下,反应温度为30～60℃,反应时间为1～5h,得到ε-己内酯。与现有技术相比,本发明创新地采用了活性氧化铝负载氧化铜作为催化剂,用于催化氧化环己酮制备ε-己内酯,且催化效果良好,反应选择性高达99％,反应几乎无副产物生成；使用了绿色友好的氧气作为氧化剂,在助氧化剂苯甲醛用量少的条件下,对于反应物环己酮有很好的氧化效果；活性氧化铝负载氧化铜催化剂容易制备、分离和回收利用,并且此催化剂使用成本廉价,具有良好的工业应用前景。(The invention relates to a method for preparing epsilon-caprolactone by catalytically oxidizing cyclohexanone in the presence of molecular oxygen, which comprises the steps of taking activated alumina loaded copper oxide as a catalyst, introducing oxygen into a certain amount of organic solvent, taking cyclohexanone as a raw material, adding an auxiliary oxidant, and reacting at the temperature of 30-60 ℃ for 1-5 hours under normal pressure to obtain the epsilon-caprolactone. Compared with the prior art, the method innovatively adopts the active alumina loaded copper oxide as the catalyst for preparing the epsilon-caprolactone by catalytic oxidation of cyclohexanone, and has good catalytic effect, the reaction selectivity is up to 99 percent, and almost no by-product is generated in the reaction; the green and friendly oxygen is used as an oxidant, and the oxidizing agent has good oxidizing effect on the reactant cyclohexanone under the condition of low dosage of the pro-oxidant benzaldehyde; the active alumina supported copper oxide catalyst is easy to prepare, separate and recycle, and the catalyst has low use cost and good industrial application prospect.)

1. A method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen is characterized by taking activated alumina loaded copper oxide as a catalyst, introducing oxygen into a certain amount of organic solvent, taking cyclohexanone as a raw material, adding an auxiliary oxidant, and reacting at the temperature of 30-60 ℃ for 1-5 hours under normal pressure to obtain the epsilon-caprolactone.

2. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 1, wherein the ratio of the molar amount of the pro-oxidant to the molar amount of cyclohexanone is 3:1 to 1: 1.

3. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 1, wherein the organic solvent is any one of 1, 2-dichloroethane and acetonitrile.

4. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 1, wherein the volume-mole ratio of the addition amount of the organic solvent to the addition amount of cyclohexanone is 2-6 ml: 1 mmol.

5. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 1, wherein the mass-mole ratio of the amount of the activated alumina-supported copper oxide catalyst to the added molar amount of cyclohexanone is 2-10 mg: 1 mmol.

6. The process of claim 1, wherein the pro-oxidant is benzaldehyde.

7. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 6, wherein the molar ratio of the added amount of benzaldehyde to the added amount of cyclohexanone is 1-3 mmol:1 mmol.

8. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 6, wherein the epsilon-caprolactone selectivity is 99.0% or more.

9. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 1, wherein the preparation method of the activated alumina-supported copper oxide catalyst is an equal volume impregnation method, and the loading amount of the copper oxide is 15-35%.

10. The method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen as claimed in claim 9, wherein the process of the equal-volume impregnation method is as follows:

adding Cu (NO)₃)₂·3H₂Dissolving O in deionized water solution, and stirring until Cu (NO)₃)₂·3H₂Dissolving O to obtain an impregnation solution;

slowly dripping the impregnating solution into gamma-Al₂O₃And after the dropwise addition, the mixture was immersed at room temperature for 24 hours, and after the immersion was completed, the mixture was dried overnight in an oven at 110 ℃, and then the dried catalyst precursor was finely ground into particles, which were then placed in a muffle furnace and calcined at 400 ℃ for 4 hours to obtain an activated alumina-supported copper oxide catalyst.

Technical Field

The invention relates to a method for preparing epsilon-caprolactone, in particular to a method for preparing epsilon-caprolactone by catalytically oxidizing cyclohexanone in the presence of molecular oxygen.

Background

The lactone compound is a key organic intermediate in chemical fine products, and plays an important role in the chemical and biological fields. As an important lactone intermediate, the epsilon-caprolactone has good performance on the dissolving capacity of polymer resin, such as chlorinated polyolefin resin and polyurethane resin, and the epsilon-caprolactone and the epsilon-polycaprolactone which are used as raw materials to synthesize environment-friendly degradable plastic can be applied to the fields of surgical products, mold release agents, adhesive films and the like. The Baeyer-Villiger (B-V) oxidation reaction is the most effective synthesis method for preparing the epsilon-caprolactone compound, but the traditional method for synthesizing the epsilon-caprolactone has higher economic cost, most of catalysts are more complex to prepare, and the reaction can not meet the requirement of green chemistry, so that the search for a green, efficient and easily synthesized catalyst for catalyzing and synthesizing the epsilon-caprolactone is very necessary.

Currently, the limitation on the yield of the Baeyer Villiger oxidation product epsilon caprolactone is often due to two factors, one being the oxidant for B-V oxidation and the other being the catalyst for B-V oxidation. From the oxidant perspective, the traditional peroxy acid has great safety hazard in management and use, and replaces the environmental-friendly oxidant H₂O₂It is necessary to exert an oxidizing action in an aqueous solution of about 30% when H is present₂O₂Above 60-70%, there is a similar risk as peracids, and H₂O₂The water by-product of the oxidation process of (3) causes slight delamination of the reaction system and may hinder the reaction of the substrate with H to some extent₂O₂Contact with the oxidizing agent also causes the oxidation product lactone to aggregate in the water, thereby reducing the yield of the product. Safe and almost cost-free oxygen is therefore the primary choice for an increasing number of researchers working on B-V oxidation.

Hazra et al used Co-Sn, Cu-Sn and Ni-Sn catalysts, the conversion of cyclohexanone was 78.5-83.1% at 50 ℃ and the selectivity of product was 85-89%, although the raw material of the catalyst was relatively cheap, the reaction yield was relatively low and the selectivity of lactone compound product was not high (Hazra S, et al. Dalton trains, 2017,46(39): 13364-13375); the Chen S Y topic group prepares a SnTPP/4A-MS catalyst, the reaction temperature is 60 ℃, the conversion rate of cyclohexanone is 83 percent, the selectivity of the product is up to 99 percent, although the selectivity of the product is high, the catalyst preparation is complex and is not suitable for industrial production (Chen S Y, et al. The use of molecular oxygen and an aldehyde as alternative oxidants to the former two poses little safety risk during the entire use and, if a suitable catalyst is chosen, the yield of the reaction is not very low, and wanling yao et al, using the organic compound N-hydroxyphthalimide (NHPI) as a catalyst to catalyze the B-V oxidation of cyclohexanone at 40 ℃ for 4h, gives a yield of up to 96% of the product epsilon-caprolactone formed from cyclohexanone, but NHPI as an organic catalyst does not separate well from the product after the reaction is complete (Wang L, et al, Chem Cat Chem 2018,10(21): 4947-4952). In the case of catalysts required for Baeyer-Villiger oxidation, most of the catalysts are relatively complicated to prepare, such as complex catalysts, and easily prepared catalysts cannot be produced in large quantities (precipitation method), so that the industrial production of Baeyer-Villiger is limited. Therefore, the search for a catalyst which is low in cost, green, environment-friendly and high in catalytic efficiency and is easy to prepare, and the search for the mild reaction conditions has great significance in preparing the epsilon-caprolactone with high yield and high selectivity by catalyzing cyclohexanone.

Disclosure of Invention

The invention aims to solve the problems, provides a method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen, and mainly solves the technical problems of difficult preparation of a catalyst, poor catalytic efficiency, excessive reaction solvent, high dosage of pro-oxidant benzaldehyde and the like in the method for preparing epsilon-caprolactone in the prior art.

The purpose of the invention is realized by the following technical scheme:

the technical scheme aims to protect a method for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone in the presence of molecular oxygen, wherein activated alumina loaded copper oxide is used as a catalyst, oxygen is introduced into a certain amount of organic solvent, cyclohexanone is used as a raw material, an pro-oxidant is added, and epsilon-caprolactone is obtained under the conditions of normal pressure, the reaction temperature of 30-60 ℃ and the reaction time of 1-5 hours.

Further, the ratio of the molar weight of the pro-oxidant to the molar weight of the cyclohexanone is 3:1 to 1: 1.

Further, the organic solvent is any one of 1, 2-dichloroethane and acetonitrile.

Further, the volume-mole ratio of the addition amount of the organic solvent to the addition amount of the cyclohexanone is 2-6 ml: 1 mmol.

Further, the mass-mole ratio of the dosage of the active alumina supported copper oxide catalyst to the added molar weight of cyclohexanone is 2-10 mg: 1 mmol.

Further, the pro-oxidant is benzaldehyde.

Further, the molar ratio of the added amount of the benzaldehyde to the added amount of the cyclohexanone is 1-3 mmol:1 mmol.

Further, the selectivity of the epsilon-caprolactone is more than or equal to 99.0 percent.

Further, the preparation method of the active alumina supported copper oxide catalyst is an isometric impregnation method, and the loading amount of the copper oxide is 15-35%.

Further, the process of the equal-volume impregnation method is as follows:

adding Cu (NO)₃)₂·3H₂Dissolving O in deionized water solution, and stirring until Cu (NO)₃)₂·3H₂Dissolving O to obtain an impregnation solution;

slowly dripping the impregnating solution into gamma-Al₂O₃And after the dropwise addition, the mixture was immersed at room temperature for 24 hours, and after the immersion was completed, the mixture was dried overnight in an oven at 110 ℃, and then the dried catalyst precursor was finely ground into particles, which were then placed in a muffle furnace and calcined at 400 ℃ for 4 hours to obtain an activated alumina-supported copper oxide catalyst.

Compared with the prior art, the invention has the advantages that the technical progress is remarkable:

1. the method innovatively adopts active aluminum oxide loaded copper oxide as a catalyst for preparing epsilon-caprolactone by catalytic oxidation of cyclohexanone, and has the advantages of good catalytic effect, reaction selectivity up to 99 percent and almost no byproduct generation in the reaction.

2. The green and friendly oxygen is used as an oxidant, and the oxidation effect on the reactant cyclohexanone is good under the condition of low dosage of the pro-oxidant benzaldehyde.

3. The active alumina supported copper oxide catalyst is easy to prepare, separate and recycle, and the catalyst has low use cost and good industrial application prospect.

Detailed Description

The invention takes benzaldehyde as an auxiliary oxidant under the catalytic action of activated alumina-loaded copper oxide, and the cyclohexanone is catalyzed and oxidized in the presence of molecular oxygen to prepare the epsilon-caprolactone, the activated alumina-loaded copper oxide is used as a catalyst in the reaction, the catalyst is prepared by adopting an isometric impregnation method, the preparation is simple, the catalyst is added into a reaction system, the reaction time is greatly reduced, the reaction selectivity reaches up to 99 percent, almost no by-product is generated in the reaction, the subsequent separation operation is simple, the oxygen source is wide, the price is low, the reaction cost is reduced, and the green chemical process of the reaction is realized.

The present invention is described in detail below with reference to specific examples, but the present invention is not limited thereto in any way.

In the examples, the conversion rate of cyclohexanone and the selectivity of epsilon-caprolactone are obtained by GC detection analysis, and the GC detection calculation method is based on an area normalization method.

Example 1

Preparation method of 30% active alumina supported copper oxide catalyst

1.1406g of Cu (NO)₃)₂·₃H₂Dissolving O in 1.8ml deionized water solution, stirring with glass rod until metal Cu salt is dissolved, and slowly adding the solution containing Cu salt to gamma-Al₂O₃Drying at 120 deg.C for 4-6h, and soaking at room temperature for 24 hrAfter the impregnation was completed, the catalyst precursor was dried overnight in an oven at 110 ℃ and then finely ground to a granular form, and then the catalyst precursor was placed in a muffle furnace and calcined at 400 ℃ for 4 hours.

0.02g of active alumina-supported copper oxide catalyst, 0.4907g of cyclohexanone, 1.0612g of benzaldehyde and 15mL of 1, 2-dichloroethane are sequentially added into a three-neck flask, then 20mL/min of oxygen is introduced under the normal pressure condition, the mixture is stirred for 4 hours at the constant temperature of 50 ℃, and finally, the conversion rate of the cyclohexanone is 98.5 percent and the selectivity of epsilon-caprolactone is higher than 99.0 percent through GC detection and analysis.

Wherein the proportion of the cyclohexanone, the benzaldehyde and the 1, 2-dichloroethane is calculated according to the molar volume ratio, namely the proportion of the cyclohexanone to the benzaldehyde to the 1, 2-dichloroethane is 1mmol to 2mmol to 3 mL; the adding amount of the active alumina supported copper oxide catalyst is calculated according to the mass ratio of the active alumina supported copper oxide catalyst to the cyclohexanone, namely the ratio of the active alumina supported copper oxide catalyst to the cyclohexanone is 0.04: 1.

Example 2

0.04g of active alumina-supported copper oxide catalyst, 0.4907g of cyclohexanone, 1.0612g of benzaldehyde and 15mL of 1, 2-dichloroethane are sequentially added into a three-neck flask, then 20mL/min of oxygen is introduced under the normal pressure condition, the mixture is stirred for 4 hours at the constant temperature of 50 ℃, and finally, the conversion rate of the cyclohexanone is 92.6 percent and the selectivity of epsilon-caprolactone is higher than 99.0 percent through GC detection and analysis.

Wherein the proportion of the cyclohexanone, the benzaldehyde and the 1, 2-dichloroethane is calculated according to the molar volume ratio, namely the proportion of the cyclohexanone to the benzaldehyde to the 1, 2-dichloroethane is 1mmol to 2mmol to 3 mL; the adding amount of the active alumina supported copper oxide catalyst is calculated according to the mass ratio of the active alumina supported copper oxide catalyst to the cyclohexanone, namely the ratio of the active alumina supported copper oxide catalyst to the cyclohexanone is 0.08: 1.

Example 3

0.02g of active alumina-supported copper oxide catalyst, 0.4907g of cyclohexanone, 1.0612g of benzaldehyde and 30mL of 1, 2-dichloroethane are sequentially added into a three-neck flask, then 20mL/min of oxygen is introduced under the normal pressure condition, the mixture is stirred for 4 hours at the constant temperature of 50 ℃, and finally, the conversion rate of the cyclohexanone is 92.1 percent and the selectivity of epsilon-caprolactone is higher than 99.0 percent through GC detection and analysis.

Wherein the proportion of the cyclohexanone, the benzaldehyde and the 1, 2-dichloroethane is calculated according to the molar volume ratio, namely the proportion of the cyclohexanone to the benzaldehyde to the 1, 2-dichloroethane is 1mmol to 2mmol to 6 mL; the adding amount of the active alumina supported copper oxide catalyst is calculated according to the mass ratio of the active alumina supported copper oxide catalyst to the cyclohexanone, namely the ratio of the active alumina supported copper oxide catalyst to the cyclohexanone is 0.04: 1.

Example 4

0.02g of active alumina-supported copper oxide catalyst, 0.4907g of cyclohexanone, 0.5306g of benzaldehyde and 15mL of 1, 2-dichloroethane are sequentially added into a three-neck flask, then 20mL/min of oxygen is introduced under the normal pressure condition, the mixture is stirred for 4 hours at the constant temperature of 50 ℃, and finally, the conversion rate of the cyclohexanone is 62.5 percent and the selectivity of epsilon-caprolactone is higher than 99.0 percent through GC detection and analysis.

Wherein the proportion of the cyclohexanone, the benzaldehyde and the 1, 2-dichloroethane is calculated according to the molar volume ratio, namely the proportion of the cyclohexanone to the benzaldehyde to the 1, 2-dichloroethane is 1mmol to 3 mL; the adding amount of the active alumina supported copper oxide catalyst is calculated according to the mass ratio of the active alumina supported copper oxide catalyst to the cyclohexanone, namely the ratio of the active alumina supported copper oxide catalyst to the cyclohexanone is 0.04: 1.

Example 5

0.02g of active alumina-supported copper oxide catalyst, 0.6310g of p-ethylcyclohexanone, 1.0612g of benzaldehyde and 15mL of 1, 2-dichloroethane are sequentially added into a three-neck flask, then 20mL/min of oxygen is introduced under the normal pressure condition, the mixture is stirred for 4 hours at the constant temperature of 50 ℃, and finally, the conversion rate of the cyclohexanone is 97.6 percent and the selectivity of epsilon-caprolactone is higher than 99.0 percent through GC detection and analysis.

Wherein the proportion of the cyclohexanone, the benzaldehyde and the 1, 2-dichloroethane is calculated according to the molar volume ratio, namely the proportion of the cyclohexanone to the benzaldehyde to the 1, 2-dichloroethane is 1mmol to 2mmol to 3 mL; the adding amount of the active alumina supported copper oxide catalyst is calculated according to the mass ratio of the active alumina supported copper oxide catalyst to the cyclohexanone, namely the ratio of the active alumina supported copper oxide catalyst to the cyclohexanone is 0.04: 1.

Comparative example 1

CN104592192A discloses a method for preparing epsilon-caprolactone, which comprises the steps of adding cyclohexanone, a catalyst, an oxidant and an auxiliary oxidant into an organic solvent, wherein the catalyst is copper chloride or supported copper chloride, the oxidant is oxygen, the auxiliary oxidant is aldehyde, and the epsilon-caprolactone can be obtained after reaction for 8-14 h under the normal pressure condition and at the temperature of 10-50 ℃. The technical scheme has the defects that in the experiment, the preparation of the catalyst needs to be carried out at a higher temperature under the protection of nitrogen, a supported copper chloride catalyst is adopted to carry out the reaction under the optimal condition, the conversion rate of the cyclohexanone can reach 94.6%, but the reaction time needs 12 hours. However, the experiment is carried out by adopting the 30% active alumina-supported copper oxide catalyst, the conversion rate of cyclohexanone can reach 98.5% only after reacting for 4 hours under the optimal condition, and the active alumina-supported copper oxide catalyst is more beneficial to industrial production than the supported copper chloride catalyst in terms of reaction time and catalytic effect.

The embodiments described above are described to facilitate an understanding and use of the invention by those skilled in the art. It will be readily apparent to those skilled in the art that various modifications to these embodiments may be made, and the generic principles described herein may be applied to other embodiments without the use of the inventive faculty. Therefore, the present invention is not limited to the above embodiments, and those skilled in the art should make improvements and modifications within the scope of the present invention based on the disclosure of the present invention.