A process for the preparation of caprolactone
By using 2-enpentol and carbon monoxide in the presence of nickel and/or cobalt, phosphorus and nitrogen ligand catalysts to prepare caprolactone, the safety risks associated with the use of peracetic acid in existing technologies have been resolved, and high-yield and selective caprolactone synthesis has been achieved, making it suitable for industrial production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- WANHUA CHEM GRP CO LTD
- Filing Date
- 2024-01-15
- Publication Date
- 2026-07-10
Smart Images
Figure QLYQS_1 
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Abstract
Description
Technical Field
[0001] This invention belongs to the field of chemical technology, specifically relating to a method for preparing caprolactone. Background Technology
[0002] PCL (polycaprolactone) is a semi-crystalline polymer with a milky white appearance and a waxy feel. It has a melting point of approximately 60℃, a Tg of approximately -60℃, and a decomposition temperature (Tc) of 350℃. It can be copolymerized and blended with many polymers and exhibits good biocompatibility and biodegradability. It can be used in the medical field, biodegradable plastic films and bags, 3D printing materials, and also in the field of polyols.
[0003] As is well known, a stable supply of monomer raw materials is a prerequisite for the widespread application of any polymer material. The healthy development of the PCL-related industry depends on a stable production capacity of ε-caprolactone. Currently, the production process of ε-caprolactone uses cyclohexanone as a raw material, obtaining the product through peracetic acid oxidation and rearrangement. However, the use and preparation of peracetic acid as an oxidant carries high safety risks, requiring extremely stringent process safety control. Only a few international chemical giants possess this technology, controlling the production and sales of ε-caprolactone and its downstream products. Furthermore, the major manufacturer, Japan's Cairwhale Chemical Co., Ltd., has experienced workshop explosions. Therefore, developing a synthetic route with a mild reaction and high safety factor is of great significance.
[0004] Summary of the Invention
[0005] To overcome the shortcomings of existing technologies, this invention provides a novel method for preparing caprolactone. The method uses 2-enpentol and carbon monoxide as raw materials, and in the presence of a catalyst, caprolactone is prepared in a subsequent step. This method features mild reaction conditions, eliminates the need for peracetic acid, achieves high yield, and has significant potential for industrial application.
[0006] To achieve the above objectives, the present invention adopts the following technical solution:
[0007] A method for preparing caprolactone includes the following steps: reacting 2-enpentol with carbon monoxide and hydrogen in the presence of a catalyst to prepare caprolactone.
[0008] The reaction equation of this invention is as follows:
[0009]
[0010] Preferably, the catalyst comprises nickel and / or cobalt, phosphorus-nitrogen ligands, and additives.
[0011] Preferably, the catalyst is prepared by adding a salt of metallic nickel and / or cobalt to an organic solvent under anhydrous and oxygen-free conditions, followed by the addition of phosphorus-nitrogen ligands and additives, and then reacting the mixture.
[0012] Preferably, the salt of metallic nickel and / or cobalt is one or more of Ni(OAc)2, Ni(acac)2, Co(OAc)2, and Co(acac)2;
[0013] The phosphorus-nitrogen ligand structure described in this invention is as follows: or One or more of the following, wherein R1, R2, and R3 are independently selected from H, -CH3, and -CH2CH3, respectively; the amount of phosphorus-nitrogen ligands added is 5-10 times the mass of the nickel and / or cobalt salts.
[0014] The adjuvants described in this invention are pyridine, sodium acetate, and 4-methylaminopyridine, and the amount used is 2-5 times the mass of the phosphorus nitrogen ligand.
[0015] In some preferred embodiments of the present invention, the catalyst is prepared by adding a salt of metallic nickel and / or cobalt to an organic solvent under anhydrous and oxygen-free conditions, followed by adding a phosphorus-nitrogen ligand, stirring for 0.5-2 hours, then adding an auxiliary agent, and stirring for 0.5-2 hours.
[0016] Preferably, the catalyst of the present invention can be directly prepared in the reaction system. More preferably, the catalyst is first prepared in an organic solvent and then added to the raw materials for lactone reaction.
[0017] Preferably, the total amount of nickel and / or cobalt salts added to the catalyst is 0.1-0.5% of the mass of 2-enpentol.
[0018] Preferably, the organic solvent is toluene, xylene, or tetrahydrofuran, and the amount used is 10-20 times the mass of 2-enpentanol.
[0019] In this invention, the volume ratio of carbon monoxide to hydrogen is 100-300:1, and the reaction temperature is 80-120℃, preferably 90-110℃.
[0020] Preferably, the reaction pressure is 5-8 MPa and the reaction time is 5-10 h.
[0021] Because the reaction pressure needs to be controlled, carbon monoxide and hydrogen are in excess relative to 2-enpentol. Carbon monoxide and hydrogen can be added according to the reaction consumption to control the pressure.
[0022] The advantages of this invention are:
[0023] 1) This invention provides a novel method for preparing caprolactone by reacting 2-enpentol with syngas in one step. This method is milder and avoids the use of highly hazardous peroxides in existing methods.
[0024] 2) To improve the selectivity and yield of the reaction, this invention also synthesizes a non-noble metal coupled phosphorus-nitrogen ligand catalyst, which is beneficial for catalyzing the reaction of 2-enpentol with syngas, greatly improving the selectivity of lactones and providing a favorable guarantee for the industrialization of this route. Detailed Implementation
[0025] The main raw materials are 2-enpentol from Bailingwei Technology Co., Ltd., CO / H2 from Dalian Date Gas Co., Ltd., Ni(OAc)2, Ni(acac)2, Co(OAc)2, and Co(acac)2 from Sigma-Aldrich, and toluene, xylene, and tetrahydrofuran from Aladdin Reagent Co., Ltd.
[0026] Procurement by Chongqing Futeng Pharmaceutical Co., Ltd.
[0027] Organophosphorus ligand 1 was prepared using the preparation method described in Example 7 of patent CN115746055 A, and its structure is as follows:
[0028]
[0029] Organophosphine ligand 2: Prepared using the preparation method described in Example 6 of patent CN115746055 A, with the following structure:
[0030]
[0031] Organophosphine ligand 3: Prepared by the method described in paragraph 4 on page 16061 of J.AM.CHEM.SOC.2006, 128, 16058-16061, by Xumu Zhang et al., with the following structure: R3 is hydrogen;
[0032] Organophosphorus ligand 4 is prepared in the same way as organophosphorus ligand 1, except that the starting material is replaced by 2-methylpyrrole instead of pyrrole.
[0033] Organophosphorus ligand 5 is prepared in the same way as organophosphorus ligand 2, except that the starting material is replaced by 2-ethylpyrrole instead of pyrrole.
[0034] Organophosphorus ligand 6 is prepared in the same way as organophosphorus ligand 3, the difference being that the starting material is changed from... Replace with
[0035] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention.
[0036] <Testing Methods>
[0037] The reaction conversion and selectivity were determined by gas chromatography. Gas chromatography was performed using an HP5890 Series II GC system with a capillary column (CP) and a flame ionization detector. The column temperature was set to 90℃ (hold for 5 min), ramped to 280℃ at a rate of 10℃ / min, held for 10 min, with the injector and detector temperatures both set to 280℃. The carrier gas flow rates were: nitrogen 30 mL / min, air 300 mL / min, and hydrogen 30 mL / min.
[0038] Example 1
[0039] (1) Catalyst preparation: Under a nitrogen atmosphere, 0.013 g Ni(OAc)2 and 129 g toluene were added to a stirred tank equipped with a self-priming impeller, followed by 0.10 g organophosphorus ligand 1, and stirred at room temperature for 0.5 h. 0.21 g pyridine was added, and stirred at room temperature for 0.5 h, and set aside.
[0040] (2) Lactoneation reaction: 12.9 g of 2-enpentanol was added to the catalyst solution from step (1), heated to 90 °C, and CO / H2 with a volume ratio of 100:1 was introduced. The pressure was maintained at 5 MPa, and the reaction was carried out for 5 h. After cooling to room temperature, the reactor was restored to atmospheric pressure, and a sample was taken for GC analysis. The conversion rate of 2-enpentanol was 95%, and the selectivity of caprolactone was 92%.
[0041] Example 2
[0042] (1) Catalyst preparation: Under a nitrogen atmosphere, 0.026g Ni(acac)2 and 155g toluene were added to a stirred tank equipped with a self-priming impeller, followed by 0.23g organophosphorus ligand 2. The mixture was stirred at room temperature for 0.1h; 0.58g sodium acetate was added and stirred at room temperature for 1h. The mixture was then set aside.
[0043] (2) Lactone reaction: 12.9 g of 2-enpentanol was added to the catalyst solution from step (1), heated to 100 °C, and CO / H2 with a volume ratio of 150:1 was introduced. The pressure was maintained at 6 MPa, and the reaction was carried out for 8 h. After cooling to room temperature, the reactor was restored to atmospheric pressure, and a sample was taken for GC analysis. The conversion rate of 2-enpentanol was 98%, and the selectivity of caprolactone was 95%.
[0044] Example 3
[0045] (1) Catalyst preparation: Under a nitrogen atmosphere, 0.039 g Co(OAc)2 and 193 g toluene were added to a stirred tank equipped with a self-priming impeller, followed by 0.39 g organophosphorus ligand 3. The mixture was stirred at room temperature for 0.2 h. Then, 1.16 g 4-methylaminopyridine was added and stirred at room temperature for 2 h. The mixture was then set aside.
[0046] (2) Lactoneation reaction: 12.9 g of 2-enpentanol was added to the catalyst solution from step (1), heated to 110 °C, and CO / H2 with a volume ratio of 200:1 was introduced. The pressure was maintained at 8 MPa, and the reaction was carried out for 10 h. After cooling to room temperature, the reactor was restored to atmospheric pressure, and a sample was taken for GC analysis. The conversion rate of 2-enpentanol was 99%, and the selectivity of caprolactone was 97%.
[0047] Example 4
[0048] The same preparation method as in Example 1 was used, except that the organophosphorus ligand was organophosphorus ligand 4. After the reaction, a sample was taken for GC analysis, and the conversion rate of 2-enpentol was 98% and the selectivity of caprolactone was 96%.
[0049] Example 5
[0050] The same preparation method as in Example 2 was used, except that the organophosphorus ligand was organophosphorus ligand 5. After the reaction, a sample was taken for GC analysis, and the conversion rate of 2-enpentol was 98% and the selectivity of caprolactone was 96%.
[0051] Example 6
[0052] The same preparation method as in Example 3 was used, except that the organophosphorus ligand was organophosphorus ligand 6. After the reaction, a sample was taken for GC analysis, and the conversion rate of 2-enpentol was 99% and the selectivity of caprolactone was 98%.
[0053] Comparative Example 1
[0054] (1) Catalyst preparation: Under a nitrogen atmosphere, 0.039 g Co(OAc)2 and 193 g toluene were added to a stirred tank equipped with a self-priming impeller, followed by 0.39 g triphenylphosphine. The mixture was stirred at room temperature for 0.2 h. Then, 1.16 g 4-methylaminopyridine was added and stirred at room temperature for 2 h. The mixture was then set aside.
[0055] (2) Lactone reaction: 12.9 g of 2-enpentanol was added to the catalyst solution from step (1), heated to 110 °C, and CO / H2 with a volume ratio of 200:1 was introduced. The pressure was maintained at 8 MPa, and the reaction was carried out for 10 h. After cooling to room temperature, the reactor was restored to atmospheric pressure, and a sample was taken for GC analysis. The conversion rate of 2-enpentanol was 90%, and the selectivity of caprolactone was 58%.
[0056] In this case, triphenylphosphine ligand was used instead of phosphorus nitrogen ligand, and the selectivity of caprolactone was only 58%, indicating that phosphorus nitrogen ligand plays a key role in improving the selectivity of caprolactone.
[0057] Comparative Example 2
[0058] (1) Catalyst preparation: Under a nitrogen atmosphere, 0.039 g Co(OAc)2 and 193 g toluene were added to a stirred tank equipped with a self-priming impeller, followed by 0.39 g of phosphorus-nitrogen ligand. Stir at room temperature for 0.2 hours, then set aside.
[0059] (2) Lactone reaction: 12.9 g of 2-enpentanol was added to the catalyst solution from step (1), heated to 110 °C, and CO / H2 with a volume ratio of 200:1 was introduced. The pressure was maintained at 8 MPa, and the reaction was carried out for 10 h. After cooling to room temperature, the reactor was restored to atmospheric pressure, and a sample was taken for GC analysis. The conversion rate of 2-enpentanol was 40%, and the selectivity of caprolactone was 90%.
[0060] In this case, no alkaline adjuvant was used. Although caprolactone selectivity was 90%, the conversion rate of 2-enpentol was only 40%.
Claims
1. A method for preparing caprolactone, characterized in that, The process includes the following steps: reacting the raw material 2-enpentol with carbon monoxide and hydrogen in the presence of a catalyst to prepare caprolactone; The catalyst comprises nickel and / or cobalt, a phosphorus-nitrogen ligand, and an auxiliary agent; the catalyst is prepared by adding a salt of metallic nickel and / or cobalt to an organic solvent under anhydrous and oxygen-free conditions, followed by the addition of a phosphorus-nitrogen ligand and an auxiliary agent, mixing, and then reacting; the structure of the phosphorus-nitrogen ligand is as follows. ;or ,or R1, R2, and R3 are independently selected from H, -CH3, and -CH2CH3, respectively; The adjuvants are pyridine, sodium acetate, and 4-methylaminopyridine, and the amount used is 2-5 times the mass of the phosphorus nitrogen ligand.
2. The preparation method according to claim 1, characterized in that, The salts of metallic nickel and / or cobalt are one or more of Ni(OAc)2, Ni(acac)2, Co(OAc)2, and Co(acac)2.
3. The preparation method according to claim 1, characterized in that, The amount of phosphorus-nitrogen ligands added is 5-10 times the mass of the nickel and / or cobalt salts.
4. The preparation method according to claim 1, characterized in that, The catalyst is prepared by adding a salt of metallic nickel and / or cobalt to an organic solvent under anhydrous and oxygen-free conditions, followed by adding a phosphorus-nitrogen ligand, stirring for 0.5-2 hours, then adding an auxiliary agent, and stirring for 0.5-2 hours.
5. The preparation method according to claim 1, characterized in that, The total amount of nickel and / or cobalt salts added to the catalyst is 0.1-0.5% of the mass of 2-enpentol.
6. The preparation method according to claim 1, characterized in that, The organic solvent is toluene, xylene, or tetrahydrofuran, and the amount used is 10-20 times the mass of 2-enpentanol.
7. The preparation method according to claim 1, characterized in that, The volume ratio of carbon monoxide to hydrogen is 100-300:1; the reaction temperature of 2-enpentol, carbon monoxide and hydrogen is 80-120℃.
8. The preparation method according to claim 7, characterized in that, The reaction temperature of 2-enpentol, carbon monoxide and hydrogen is 90-110℃.
9. The preparation method according to claim 1, characterized in that, The reaction pressure of 2-enpentol, carbon monoxide and hydrogen is 5-8 MPa, and the reaction time is 5-10 h.