A process for the preparation of a cyclic poly(delta-valerolactone)

Abstract

This invention discloses a cyclic poly( δ The preparation method of β-valerolactone, with δ Using valproic acid as a monomer and a diethylene glycol amino-bridged diaryloxyaluminum complex with a well-defined structure, simple synthesis, and high catalytic efficiency as a catalyst, a ring-opening polymerization reaction was carried out to obtain cyclic poly(( δ -Velolactone). The catalyst used in this invention is a cyclic poly( δ The controllable preparation of β-valerol provides an efficient and easily achievable catalytic system, significantly reducing the operational difficulty and cost of the preparation process, and enabling the preparation of pure cyclic topologically structured poly(β-valerol) with high molecular weight and narrow molecular weight distribution. δ (-Velolactone), without the generation of linear polymer impurities, eliminates the need for subsequent cumbersome separation and purification steps, simplifying the preparation process, further improving preparation efficiency and reducing preparation costs.

Description

Technical Field

[0001] This invention relates to the field of polymer preparation technology, specifically to a cyclic polymer (…). d Preparation method of valproic acid (-valproic acid). Background Technology

[0002] Cyclic polymers, due to their unique topological structure lacking end groups, exhibit different physicochemical properties compared to linear polymers, including smaller hydrodynamic radii, lower intrinsic viscosity, higher thermal stability, and higher glass transition temperatures. T g and higher melting point ( T m These properties give it broad application prospects in fields such as biomedicine and functional materials, making it a research hotspot in polymer chemistry and supramolecular chemistry.

[0003] Aliphatic polyesters, as a viable alternative to non-renewable or recalcitrant plastics, have significant environmental and application value. Among them, poly(… d β-valerate (Velolactone) has shown outstanding application potential in the biomedical field, such as drug delivery systems and tissue engineering scaffolds, due to its abundant raw material sources, simple chemical structure, and simultaneous hydrolysis, biodegradability, good processability, flexibility, and biocompatibility.

[0004] Currently, cyclic polymers ( d The synthesis of β-valerol mainly relies on two technical pathways: ring-closure and ring-expansion. Ring-closure requires intramolecular cyclization using the active functional groups at the polymer chain ends; however, this process is prone to intermolecular side reactions that generate linear impurities, and it requires highly diluted conditions. Furthermore, the cyclization efficiency decreases significantly with increasing molecular weight of the target polymer, making subsequent separation and purification processes cumbersome. While ring-expansion has become a mainstream research direction in recent years, existing techniques still have significant limitations. In 2023, Eugene Y.-X. Chen's research group used yttrium, lanthanum, and zinc metal complexes for catalysis... d - The ring-opening polymerization of valproic acid yields a mixture of cyclic and linear polymers without alcohol initiation, but a purely linear product is obtained with the addition of an alcohol initiator. In 2024, Carl Redshaw et al. used molybdenum complexes as catalysts, and the products were also a mixture of linear and cyclic polymers with a wide molecular weight distribution. In 2025, Haiian Xia's research group used a two-component catalytic system composed of trichlorophenylurea and an organic base. Although a product dominated by cyclic polymers could be obtained without an initiator, the generation of linear impurities could not be completely avoided. Essentially, cyclic polymers... dThe formation of β-valerol (β-valerol) depends on intramolecular transesterification, which is often accompanied by the formation of linear polymers. Furthermore, the transesterification rate is difficult to control precisely, making it difficult for existing technologies to simultaneously achieve the preparation goals of pure cyclic topology, high molecular weight and narrow molecular weight distribution.

[0005] Therefore, it is necessary to develop a highly active, mild reaction method that can prepare high-molecular-weight, narrow-molecular-weight pure cyclic poly(p-C) polymers. d The preparation method of β-valerol has significant technical value and application prospects. Summary of the Invention

[0006] The purpose of this invention is to solve the above-mentioned technical problems and provide a cyclic polymer ( d A method for preparing β-valerolactone (β-valerol) uses a diethylene glycol amino-bridged diaryloxyaluminum complex as a catalyst. The structure-specificity of this catalyst allows for the control of the ring-opening polymerization reaction. The reaction conditions are mild and highly controllable, enabling the efficient preparation of pure cyclic poly(β-valerolactone) without linear impurities. d The product obtained has the characteristics of high molecular weight and narrow molecular weight distribution, and does not require complicated subsequent separation and purification steps.

[0007] The above-mentioned objective of the present invention is achieved through the following technical solution:

[0008] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0009] Under the protection of inert gas, d -Valactone and diethylene glycol amino-bridged diaryloxyaluminum complexes are dissolved in an organic solvent and subjected to ring-opening polymerization at 30-80 °C to obtain the cyclic polymer(s). d -valerolactone);

[0010] The structural formula of the diethylene glycol amino-bridged diaryloxyaluminum complex is as follows: Among them, R 1 R 2 Each was independently selected from tert-butyl ( t One of Bu, methyl (Me), cumyl (Cumyl), and chlorine (Cl);

[0011] The cyclic polymer ( d The structural formula of (-valerolactone) is: Where n is 122-3020.

[0012] This invention is based on dUsing valerol as the monomer, a diethylene glycol amino-bridged diaryloxy aluminum complex with a well-defined structure, simple synthesis, and high catalytic efficiency was employed as the catalyst. The diethylene glycol amino-bridged diaryloxy structure of this catalyst provides a stable coordination environment for the aluminum center, enhancing its catalytic efficiency. d During the ring-opening polymerization of valproic acid, it can precisely attack the ester bonds of the monomer to achieve controllable ring opening. Simultaneously, through intramolecular coordination, it guides the polymer chain to undergo directional cyclization, effectively suppressing intermolecular side reactions and the formation of linear polymers. From a reaction mechanism perspective, this achieves pure cyclic polymerization. d The method for the directional preparation of β-valerolactone utilizes the structure-specificity and high catalytic efficiency of the catalyst, employs mild reaction conditions and offers excellent catalytic controllability, yielding a product with a pure cyclic topological structure. d It contains valerate and has the excellent properties of high molecular weight and narrow molecular weight distribution.

[0013] Furthermore, the inert gas is nitrogen or argon. Inert gases are chemically stable and can effectively isolate oxygen and moisture from the air, preventing them from reacting with the active sites of the catalyst and causing catalytic deactivation, while also preventing moisture-induced deactivation. d The hydrolysis of valproic acid acts as a side reaction, ensuring the smooth progress of the ring-opening polymerization reaction.

[0014] Furthermore, the aforementioned d The molar ratio of valproic acid to diethylene glycol aminobridged diaryloxyaluminum complex is (100-1000):1, preferably (100-500):1.

[0015] Further, the organic solvent is selected from one or more of toluene, chlorobenzene, fluorobenzene, bromobenzene, n-hexane, and tetrahydrofuran, preferably chlorobenzene. Cyclic poly(...) prepared using chlorobenzene... d β-valerolactone has a narrow molecular weight distribution and a relatively high molecular weight.

[0016] Furthermore, d -Valactone and diethylene glycol amino-bridged diaryloxyaluminum complex dissolved in an organic solvent to obtain a mixed solution, wherein d The concentration of valproic acid in the mixed solution is 2.0-5.4 mol / L, preferably 3.0-5.4 mol / L.

[0017] The catalyst of this invention exhibits catalytic activity in the range of 30-80 °C, with mild reaction conditions, eliminating the need for high-temperature heating and significantly reducing equipment requirements and energy consumption.

[0018] Furthermore, the preferred temperature for the ring-opening polymerization reaction is 30-50 °C.

[0019] Furthermore, the ring-opening polymerization reaction takes 25 min to 12 h, preferably 25 min to 6 h.

[0020] Furthermore, after the ring-opening polymerization reaction is completed, the reaction product is further subjected to sedimentation, filtration, and drying steps.

[0021] Furthermore, hexane is added to precipitate the reaction product.

[0022] Furthermore, the drying is carried out in a vacuum drying oven at a temperature of 40-60 °C and a vacuum degree of 0.05-0.2 MPa.

[0023] Furthermore, the cyclic polymer ( d The molecular weight distribution index of β-valerolactone is 1.11-1.35.

[0024] Furthermore, the cyclic polymer ( d -Velolactone is a cyclic topologically structured poly( d -Velolactone), no linear polymer impurities are generated.

[0025] The above-described technical solution of the present invention has the following beneficial effects:

[0026] 1. The diethylene glycol amino-bridged diaryloxyaluminum complex catalyst used in this invention has the characteristics of well-defined structure and simple synthesis, and is a cyclic poly( d The controllable preparation of β-valerolactone provides an efficient and easily achievable catalytic system, significantly reducing the operational difficulty and cost of the preparation process.

[0027] 2. The catalyst of the present invention has excellent catalytic activity, which can effectively improve the efficiency of ring-opening polymerization reaction and polymer yield, and the reaction conditions are mild, without the need for a harsh reaction environment and complex equipment requirements.

[0028] 3. This invention can produce high molecular weight polymers with narrow molecular weight distribution. d -valerolactone), specifically a poly( ) with a purely cyclic topological structure. d -Velolactone, without the generation of linear polymer impurities, eliminates the need for subsequent cumbersome separation and purification steps, simplifying the preparation process while further improving preparation efficiency and reducing preparation costs. Attached Figure Description

[0029] Figure 1 The cyclic poly([…]) prepared in Example 1 d Matrix-assisted laser desorption / ionization time-of-flight mass spectra of valproic acid (-valproic acid).

[0030] Figure 2 The cyclic poly([…]) prepared in Example 1 d The proton NMR spectrum of valproic acid (-valproic acid). Detailed Implementation

[0031] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used herein in the description of the invention is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0032] This invention provides a cyclic poly( d The preparation method of β-valerolactone includes the following steps:

[0033] Under the protection of inert gas, d -Valactone and diethylene glycol amino-bridged diaryloxyaluminum complexes are dissolved in an organic solvent and subjected to ring-opening polymerization at 30-80 °C to obtain the cyclic polymer(s). d -valerolactone);

[0034] The structural formula of the diethylene glycol amino-bridged diaryloxyaluminum complex is as follows: Among them, R 1 R 2 Each was independently selected from tert-butyl ( t One of Bu, methyl (Me), cumyl (Cumyl), and chlorine (Cl);

[0035] The cyclic polymer ( d The structural formula of (-valerolactone) is: Where n is 122-3020.

[0036] In a specific implementation, cyclic polymers ( d The preparation method of β-valerol includes the following steps:

[0037] (1) In a glove box protected by high-purity nitrogen, add diethylene glycol amino-bridged diaryloxyaluminum complex to a reaction flask that has been dehydrated and deoxygenated, then add organic solvent and mix well to obtain a catalyst solution; then add to the reaction flask using a pipette. d -Velolactone, reacted with stirring at 30-80 ℃;

[0038] (2) After the reaction is complete, hexane is added to precipitate the reaction product. After filtration, the solid product is dried in a vacuum drying oven to obtain the cyclic polymer. d -Velolactone).

[0039] Step (2) is a simplified purification and post-processing step after the ring-opening polymerization reaction, utilizing the cyclic polymer ( dThe poor solubility of β-valerolactone in hexane was addressed by adding hexane to induce rapid precipitation of the reaction product. After filtration to remove solvent, unreacted monomers, and catalyst residue, the product was dried to obtain the pure cyclic poly(β-valerolactone). d -Velolactone). This invention suppresses the formation of linear impurities from the reaction mechanism perspective, and the product is a pure cyclic poly( d Therefore, it eliminates the need for complex purification steps such as column chromatography and recrystallization. High-purity products can be obtained through the simple post-processing described above, which greatly simplifies the preparation process and improves production efficiency.

[0040] The present invention will be further described below with reference to the accompanying drawings and specific embodiments, so that those skilled in the art can better understand and implement the present invention. However, the embodiments described are not intended to limit the present invention.

[0041] Unless otherwise specified, the experimental methods used in the following examples are conventional methods, and the materials and reagents used are commercially available.

[0042] Example 1

[0043] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0044] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of tetrahydrofuran and mix well to obtain a catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0045] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.28 g of cyclic poly( d -Velolactone), with a yield of 28%.

[0046] The cyclic polymer obtained in Example 1 d The polymer (-valerol) was characterized by gel permeation chromatography (GPC) to determine its properties. M nIt has a molecular weight of 60.8 kg / mol and a molecular weight distribution index of 1.16.

[0047] Figure 1 The cyclic poly([…]) prepared in Example 1 d Matrix-assisted laser desorption / ionization time-of-flight mass spectra of β-valerolactone (MAV) from Figure 1 As can be seen, the mass-to-charge ratio (m / z) of each peak follows the pattern m / z = 100.06n + 22.99, where 100.06 corresponds to d The relative molecular mass of the -valerol repeating unit, 22.99, is that of the sodium ion (Na). + The quality of the polymer was confirmed. This result confirms that the obtained polymer is a pure cyclic polymer. d -valerolactone), and nonlinear poly( d -Velolactone).

[0048] Figure 2 The cyclic poly([…]) prepared in Example 1 d The proton NMR spectrum of β-valerolactone. Figure 2 The absence of characteristic peaks corresponding to the terminal hydroxyl groups of the linear polymer further confirms the pure cyclic topology of the obtained polymer.

[0049] Example 2

[0050] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0051] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of toluene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0052] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.85 g of cyclic poly( d -Velolactone), with a yield of 85%.

[0053] The cyclic polymer obtained in Example 2 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer was measured. M n It has a molecular weight of 158.4 kg / mol and a molecular weight distribution index of 1.28.

[0054] Example 3

[0055] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0056] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of fluorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0057] (2) After the reaction was completed, the reaction flask was removed from the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.52 g of cyclic poly( d -Velolactone), with a yield of 52%.

[0058] The cyclic polymer obtained in Example 3 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a concentration of 37.1 kg / mol and a molecular weight distribution index of 1.14.

[0059] Example 4

[0060] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0061] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of bromobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0062] (2) After the reaction was completed, the reaction flask was removed from the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.20 g of cyclic poly( d -Velolactone), with a yield of 20%.

[0063] The cyclic polymer obtained in Example 4 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a concentration of 50.0 kg / mol and a molecular weight distribution index of 1.19.

[0064] Example 5

[0065] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0066] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of n-hexane and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0067] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.80 g of cyclic poly( d -Velolactone), with a yield of 80%.

[0068] The cyclic polymer obtained in Example 5 ( dGPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 185.8 kg / mol and a molecular weight distribution index of 1.23.

[0069] Example 6

[0070] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0071] (1) In a glove box protected by high-purity nitrogen, add 0.0283 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0072] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.44 g of cyclic poly( d -Velolactone), with a yield of 44%.

[0073] The cyclic polymer obtained in Example 6 d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a concentration of 69.0 kg / mol and a molecular weight distribution index of 1.13.

[0074] Example 7

[0075] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0076] (1) In a glove box protected by high-purity nitrogen, add 0.0566 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.1 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid to the diethylene glycol amino-bridged diaryloxyaluminum complex is 100:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0077] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.73 g of cyclic poly( d -Velolactone), with a yield of 73%.

[0078] The cyclic polymer obtained in Example 7 d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 135.4 kg / mol and a molecular weight distribution index of 1.22.

[0079] Example 8

[0080] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0081] (1) In a glove box protected by high-purity nitrogen, add 0.0566 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.1 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Then add 1.86 mL of chlorobenzene and mix well to obtain the catalyst solution; subsequently, add 0.93 mL of the catalyst solution to the reaction flask using a pipette. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid to the diethylene glycol amino-bridged diaryloxyaluminum complex is 100:1. d The concentration of β-valerol in the mixed solution was 3.6 mol / L, and the reaction was carried out by stirring at 30 °C for 25 min.

[0082] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.48 g of cyclic poly( d -Velolactone), with a yield of 48%.

[0083] The cyclic polymer obtained in Example 8 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M nIt has a molecular weight of 82.9 kg / mol and a molecular weight distribution index of 1.13.

[0084] Example 9

[0085] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0086] (1) In a glove box protected by high-purity nitrogen, add 0.0258 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. d The concentration of β-valerol in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 6 h.

[0087] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.54 g of cyclic poly( d -Velolactone), with a yield of 54%.

[0088] The cyclic polymer obtained in Example 9 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 27.9 kg / mol and a molecular weight distribution index of 1.17.

[0089] Example 10

[0090] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0091] (1) In a glove box protected by high-purity nitrogen, add 0.0516 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.1 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid to the diethylene glycol amino-bridged diaryloxyaluminum complex is 100:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 4.5 h.

[0092] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.45 g of cyclic poly( d -Velolactone), with a yield of 45%.

[0093] The cyclic polymer obtained in Example 10 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a concentration of 12.2 kg / mol and a molecular weight distribution index of 1.11.

[0094] Example 11

[0095] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0096] (1) In a glove box protected by high-purity nitrogen, add 0.0113 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.02 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Then add 1.86 mL of chlorobenzene and mix well to obtain the catalyst solution; subsequently, add 0.93 mL of the catalyst solution to the reaction flask using a pipette. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 500:1. d The concentration of β-valerol in the mixed solution was 3.6 mol / L, and the reaction was carried out by stirring at 30 °C for 1.3 h.

[0097] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.92 g of cyclic poly( d -Velolactone), with a yield of 92%.

[0098] The cyclic polymer obtained in Example 11 d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 246.0 kg / mol and a molecular weight distribution index of 1.17.

[0099] Example 12

[0100] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0101] (1) In a glove box protected by high-purity nitrogen, add 0.0057 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.01 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid to the diethylene glycol amino-bridged diaryloxyaluminum complex is 1000:1. d The concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 2.5 h.

[0102] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.99 g of cyclic poly( d -Velolactone), with a yield of 99%.

[0103] The cyclic polymer obtained in Example 12 d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 302.0 kg / mol and a molecular weight distribution index of 1.35.

[0104] Example 13

[0105] A cyclic polymer ( d The preparation method of β-valerolactone includes the following steps:

[0106] (1) In a glove box protected by high-purity nitrogen, add 0.0258 g of diethylene glycol amino-bridged diaryloxyaluminum complex (0.05 mmol, structural formula: [insert structural formula here]) to a 10 mL reaction flask that has been dehydrated and deoxygenated. Add 0.93 mL of chlorobenzene and mix well to obtain the catalyst solution; then use a pipette to add 0.93 mL of the catalyst solution to the reaction flask. d -Velolactone yields a mixed solution. d The molar ratio of valproic acid lactone to the diethylene glycol amino-bridged diaryloxyaluminum complex is 200:1. dThe concentration of valproic acid in the mixed solution was 5.4 mol / L, and the reaction was carried out by stirring at 30 °C for 12 h.

[0107] (2) After the reaction was completed, the reaction flask was transferred out of the glove box, and 50 mL of n-hexane was added at room temperature (25 °C) to precipitate the reaction product for 15 min. After filtration, the solid product was placed in a vacuum drying oven at 50 °C and a vacuum degree of 0.1 MPa for 24 h to obtain 0.72 g of cyclic poly( d -Velolactone), with a yield of 72%.

[0108] The cyclic polymer obtained in Example 13 ( d GPC characterization of the polymer (-valerolactone) was performed, and the polymer's properties were measured. M n It has a molecular weight of 38.2 kg / mol and a molecular weight distribution index of 1.32.

[0109] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art should understand that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A cyclic polymer ( δ The method for preparing β-valerolactone is characterized by, Includes the following steps: Under the protection of inert gas, δ -Valactone and diethylene glycol amino-bridged diaryloxyaluminum complexes are dissolved in an organic solvent and subjected to ring-opening polymerization at 30-80 °C to obtain the cyclic polymer(s). δ -valerolactone); the δ The molar ratio of valproic acid lactone to diethylene glycol amino-bridged diaryloxyaluminum complex is (100-1000):1; the organic solvent is selected from one or more of toluene, chlorobenzene, fluorobenzene, bromobenzene, n-hexane and tetrahydrofuran; The structural formula of the diethylene glycol amino-bridged diaryloxyaluminum complex is as follows: Among them, R 1 R 2 Each is independently selected from one of tert-butyl, methyl, cumyl, and chlorine; The cyclic polymer ( δ The structural formula of (-valerolactone) is: Where n is 122-3020.

2. The preparation method according to claim 1, characterized in that, The inert gas is nitrogen or argon.

3. The preparation method according to claim 1, characterized in that, Will δ -Valactone and diethylene glycol amino-bridged diaryloxyaluminum complex dissolved in an organic solvent to obtain a mixed solution, wherein δ -Velolactone concentration in the mixed solution was 2.0-5.4 mol / L.

4. The preparation method according to claim 1, characterized in that, The ring-opening polymerization reaction is carried out at a temperature of 30-50℃.

5. The preparation method according to claim 1, characterized in that, The ring-opening polymerization reaction takes 25 min to 12 h.

6. The preparation method according to claim 1, characterized in that, The ring-opening polymerization reaction also includes steps of settling, filtering, and drying the reaction products after the reaction is completed.

7. The preparation method according to claim 6, characterized in that, Add n-hexane to precipitate the reaction product.

8. The preparation method according to claim 1, characterized in that, The cyclic polymer ( δ The molecular weight distribution index of β-valerolactone is 1.11-1.35.

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