A dual active center tetra-initiator and a preparation method and application thereof

Abstract

The application discloses a dual-active-center four-initiation initiator and a preparation method and application thereof. The initiator has the following advantages: four reaction active sites are provided by the four-end initiator design, and the initiation efficiency is high; metal residues are completely avoided by the non-metal composition of the homogeneous phase, the product has high purity, and the initiator is particularly suitable for fields with strict purity requirements such as medicines and high-performance polymers; the mass transfer efficiency of the homogeneous phase system is high, and the reaction has good controllability; the synthesis route is simple, raw materials are easy to obtain, and the initiator can be operated in an air atmosphere, and has the advantages of low energy consumption, low cost, high yield and easy purification, and provides a feasible technical path for industrial production.

Description

Technical Field

[0001] This invention belongs to the field of organic chemistry, specifically, it relates to a dual-active-center tetra-initiator, its preparation method, and its application. Background Technology

[0002] With the development of modern polymer chemistry, anionic polymerization has been widely applied in materials science, pharmaceutical engineering, coatings industry, and environmental protection. The efficiency and controllability of anionic polymerization have always been important research topics in this field. As the core of anionic polymerization, the selectivity and initiation activity of the anionic polymerization initiator directly determine the reaction rate, the molecular structure of the product, and the final polymer properties. Therefore, developing novel, highly efficient initiators is a key research focus in organic chemistry.

[0003] Traditional anionic polymerization initiators, especially heterogeneous metal initiators, have achieved initial success in several polymerization reactions, but they still face some significant challenges in practical production and application. First, heterogeneous metal initiators typically rely on transition metals (such as titanium, aluminum, zirconium, and cobalt) to catalyze the reaction. While these transition metals exhibit high catalytic activity, their unique metallic properties and reaction mechanisms often lead to side reactions, resulting in reduced polymerization selectivity. Furthermore, metal residue contamination frequently negatively impacts the purity of the final product, particularly in the preparation of high-performance polymers and in the pharmaceutical field, where metal residues often become a major obstacle to meeting stringent quality standards.

[0004] In recent years, homogeneous nonmetallic initiators have gradually become a research hotspot. Homogeneous nonmetallic initiators have low toxicity and high environmental friendliness. Because they do not contain metal elements, they can effectively avoid metal pollution problems. Especially in polymerization reactions, homogeneous nonmetallic initiators can not only provide sufficient reactivity, but also improve polymer performance by optimizing their molecular structure and adjusting the selectivity and molecular weight distribution of the polymerization reaction.

[0005] Among numerous homogeneous nonmetallic initiators, tetraterminal initiators have become a research focus due to their unique structure. By introducing multiple end groups, tetraterminal initiators provide multiple reaction sites, a structural characteristic that enables them to offer higher reactivity during reactions. Furthermore, the initiation ability of tetraterminal initiators can be further enhanced through rational molecular structure design, thus exhibiting good applicability and high efficiency in various polymerization reactions. Currently, acid-base neutralization reactions remain the primary method for preparing tetraterminal initiators.

[0006] The design concept of dual-active-center tetra-initiators provides a new approach to optimizing the performance of four-terminal initiators. Unlike traditional multi-active-center initiators, dual-active-center tetra-initiators construct two active centers and configure four initiation sites on the same molecular backbone, achieving a synergistic effect of "dual active source-quadruple functional group initiation." This structural feature not only ensures that all polymer chains are initiated and grown under identical chemical conditions, fundamentally avoiding the problem of widened molecular weight distribution caused by activity differences and mutual interference between multiple active centers, but also significantly improves initiation efficiency through the configuration of four functional groups, resulting in excellent controllability and selectivity in the polymerization reaction. More importantly, the homogeneous dual-active-center system constructed based on acid-base neutralization reaction has a well-defined composition and uniform structure, completely eliminating the risk of metal residues and resulting in high product purity, making it particularly suitable for the preparation of high-end polymers with stringent requirements for impurity content. Simultaneously, the homogeneous characteristics of dual-active-center tetra-initiators ensure good mass transfer efficiency in the reaction system, enabling the polymerization process to proceed efficiently under mild conditions. It combines multiple advantages such as high catalytic activity, strong reaction controllability, and regular product structure, demonstrating broad prospects for industrial application. Summary of the Invention

[0007] The purpose of this invention is to overcome the shortcomings of existing technologies and provide a dual-active-center tetra-initiator and its preparation method. The initiator of this invention has significant structural features and performance advantages: the tetra-terminal initiator design provides four reactive sites, resulting in high initiation efficiency; the homogeneous non-metallic composition completely avoids metal residue contamination, leading to high product purity, making it particularly suitable for fields with strict purity requirements, such as pharmaceuticals and high-performance polymers; the homogeneous system has high mass transfer efficiency and good reaction controllability; the synthetic route is simple, the raw materials are readily available, and the process can be carried out under air atmosphere, resulting in low energy consumption, low cost, high yield, and easy purification, providing a practical technical path for industrial production.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: A dual-active-center tetra-initiator has the following structure: R1 is selected from H, halogens, and C1-C atoms with or without O, S, N, Si, or P atoms. 30 One of the alkyl groups; R2 is selected from C6-C atoms with or without O, S, N, and P atoms. 20 The aromatic group, wherein the substituents of the aromatic group are H, halogen, or no substituents, wherein the carboxyl group and the hydroxyl group are ortho-or ...

[0009] The preparation method of the dual-active-center tetra-initiator involves obtaining it by reacting a tetrafunctional organic compound with an organic base via an acid-base neutralization reaction; the molar ratio of the organic base to the difunctional organic compound is 2:1.

[0010] Preferably, the tetrafunctional organic compound is selected from the following structures:

[0011] Preferably, the organic base is a salt formed by an organic cation and an inorganic anion, wherein the inorganic anion is a hydroxide ion. The organic cation is selected from the following structures:

[0012] The preparation method of the above-mentioned dual-active-center four-initiator includes the following steps: (1) Mix the tetrafunctional organic compound with the organic base and stir at room temperature until completely dissolved; (2) Stir the reaction mixture obtained in step (1) at 60°C for 3 hours; (3) Place the crude product of the dual-active-center tetra-initiator obtained in step (2) into a freeze-drying oven for freeze-drying treatment; (4) The crude product of the dual active center tetra-initiator obtained in step (3) is separated by filtration with acetone solution, washed to remove impurities, and finally vacuum dried to obtain the dual active center tetra-initiator.

[0013] The dual-active-center tetra-initiator is used in the preparation of low-molecular-weight polymers or high-molecular-weight polymers. A chain transfer agent is also added, with the amount of chain transfer agent ranging from 0% to 10,000,000% of the molar amount of the dual-active-center tetra-initiator. The chain transfer agent is selected from one or more small-molecule or large-molecule polymers containing functional groups such as amino, mercapto, hydroxyl, phenolic hydroxyl, and carboxyl groups, i.e., polymers with active hydrogen. The low-molecular-weight polymer or high-molecular-weight polymer is an aliphatic polycarbonate obtained by copolymerizing carbon dioxide with epoxides, an aromatic polyester polycarbonate obtained by copolymerizing carbon dioxide with epoxides and phthalic anhydride, a polyether obtained by ring-opening polymerization of epoxides, a polythiocarbonate obtained by ring-opening polymerization of carbon dioxide and cyclothioalkanes, a polysulfide obtained by ring-opening cyclic sulfides, a polyester obtained by catalyzing the ring-opening polymerization of epoxides and cyclic anhydrides, a polyester obtained by ring-opening polymerization of lactones, a polyester obtained by ring-opening O-carboxylic anhydrides, or a polypeptide obtained by catalyzing N-carboxylic anhydrides.

[0014] The epoxides, cyclothioalkylenes, cyclic anhydrides, and lactones are selected from the following structures:

[0015] Among them, R1 and R2 are selected from H, halogens, and C1-C atoms with or without O, S, N, Si, and P atoms. 30 Alkyl, C3-C 30 cycloalkyl, C2-C30 alkenyl, C2-C 30 alkynyl group, C6-C 30 Aromatic group, C3-C 30 One or more of the heterocyclic groups.

[0016] Compared with the prior art, the present invention has the following beneficial effects: (1) Avoid side reactions and pollution problems of heterogeneous metal initiators: The present invention adopts a homogeneous non-metallic dual active center four-initiator, which avoids the side reactions and metal residue pollution problems caused by traditional heterogeneous metal initiators, improves the activity and selectivity of polymerization reaction, and is especially suitable for applications with strict purity requirements in high-performance polymers and pharmaceutical fields.

[0017] (2) It has the advantages of simple synthesis, few reaction steps, air atmosphere, low energy consumption, low cost, high yield and easy purification, which further improves the operability and economy of the process and is suitable for large-scale production.

[0018] (3) The dual-active-center tetra-initiator constructs two active centers and configures four initiation sites on the same molecular backbone, realizing the synergistic effect of "dual active source-quadrifunctional group initiation". This structural feature not only ensures that all polymer chains are initiated and grown in the same chemical environment, fundamentally avoiding the problem of widening of molecular weight distribution caused by the activity difference and mutual interference between multiple active centers, but also the configuration of the four functional groups significantly improves the initiation efficiency, making the polymerization reaction exhibit excellent controllability and selectivity.

[0019] (4) It provides a green and environmentally friendly alternative: The homogeneous nonmetallic initiator of the present invention not only has low toxicity, meeting the requirements of green chemistry, but also avoids metal pollution, conforms to the trend of environmental friendliness, and adapts to the growing demand for sustainable and environmentally friendly materials. The present invention has significant performance advantages and broad application potential, especially in polymer synthesis and the development of environmentally friendly materials, demonstrating great scientific research and industrial value. Attached Figure Description

[0020] Figure 1 This is the NMR spectrum of B1, a tetra-initiator with two active centers. Detailed Implementation

[0021] The present invention can be further explained and illustrated in conjunction with the following specific embodiments, but the specific embodiments do not limit the present invention in any way.

[0022] The following are the structural formulas of the dual-active-center four-initiator synthesized in the examples:

[0023] Example 1: First, 0.01 mol of tartaric acid was dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the tartaric acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B1.

[0024] Example 2: First, 0.01 mol of 2,3,4-trihydroxyglutaric acid was weighed and dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 2,3,4-trihydroxyglutaric acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B2.

[0025] Example 3: First, 0.01 mol of 4,6-dihydroxy-5-methyl-1,3-phthalic acid was dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The mixture was stirred at room temperature (25°C) for 1 hour until the 4,6-dihydroxy-5-methyl-1,3-phthalic acid was completely dissolved. After dissolution, the mixture was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B3.

[0026] Example 4: First, 0.01 mol of 2,4-dihydroxyisophthalic acid was dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 2,4-dihydroxyisophthalic acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B4.

[0027] Example 5: First, 0.01 mol of 3,6-dihydroxy-2,7-naphthalenedicarboxylic acid was weighed and dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 3,6-dihydroxy-2,7-naphthalenedicarboxylic acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B5.

[0028] Example 6: First, 0.01 mol of 2,3-dihydroxy-1,4-phthalic acid was weighed and dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 2,3-dihydroxy-1,4-phthalic acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B6.

[0029] Example 7: First, 0.01 mol of 2,4-dihydroxy-1,3-phthalic acid was weighed and dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 2,4-dihydroxy-1,3-phthalic acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B7.

[0030] Example 8: First, 0.01 mol of 5-methyl-4,6-dihydroxyisophthalic acid was dissolved in 0.02 mol of tetrabutylammonium hydroxide solution. The solution was stirred at room temperature (25°C) for 1 hour until the 5-methyl-4,6-dihydroxyisophthalic acid was completely dissolved. After dissolution, the solution was stirred at 60°C for 3 hours. After the reaction was complete, the reaction solution was slowly poured into acetone solution, and the resulting white precipitate was separated by filtration. Next, the precipitate was washed with diethyl ether solution 2 to 3 times. The product was then transferred to a freeze dryer at -50°C for vacuum drying until completely dry, finally yielding the dual-active-center tetra-initiator B8.

[0031]

[0032]

[0033] In a glove box, a dual-active-center tetra-initiator and TEB were added to an autoclave in the appropriate proportions, along with 0.01 mol of epoxide, and CO2 was introduced at 1 MPa. The reaction was carried out at 60°C for 6 h. After the carbon dioxide was released, the reaction solution was analyzed by NMR to characterize the monomer conversion rate and the product selectivity (the proportions of polycarbonate, polyether, and cyclic carbonate). The test results are shown in Table 1.

[0034] Table 1. Test results of initiator products in Application Examples 1-11 a

[0035] Among them, the test results a After 8 hours, the conversion rate of epoxides reached over 99%; proportion b : Epoxyalkane: TEB: Initiator: Chain transfer agent molar ratio; M n c Number-average molecular weight, determined by gel permeation chromatography; PDI d Molecular weight distribution, determined by gel permeation chromatography.

[0036] Application Example 12-22: Homopolymerization of epoxy alkane using a dual-active-center tetra-initiator

[0037] In a glove box, the dual-active-center tetra-initiator B1 / B2 / B3 / B4 / B5 and TEB were added to a serum bottle in the specified ratio, along with alkoxyalkane (0.1 mol). The reaction was carried out at 60 °C for 6 h. The reaction solution was analyzed by NMR to characterize the monomer conversion and product selectivity. After drying, the target polyether was obtained. The polymer was characterized by GPC. The polymerization results and characterization are shown in Table 2.

[0038] Table 2. Test results of initiator products in Application Examples 12-22 a

[0039] Among them, the test results a After 8 hours, the conversion rate of epoxides reached over 99%; proportion b : Epoxyalkane: TEB: Initiator: Chain transfer agent molar ratio; Mn c Number-average molecular weight, determined by gel permeation chromatography; PDI d Molecular weight distribution, determined by gel permeation chromatography.

[0040] Application Examples 23-28: Homopolymerization of Cyclic Lactones Using a Two-Active-Center Tetra-Initiator

[0041] In a glove box, the dual-active-center tetra-initiator B1 / B3 / B6 / B7 and TEB were added to a serum bottle in the specified ratio, along with a cyclic lactone (0.01 mol) and 1 mL of toluene. The reaction was carried out at 60 °C for 6 h. The reaction solution was analyzed by NMR to characterize the monomer conversion and product selectivity. After drying, the target polyester was obtained. The polymer was characterized by GPC. The polymerization results and characterization are shown in Table 3.

[0042] Table 3. Test results of initiator products in Application Examples 23-28

[0043] Among them, proportion a : Epoxyalkane: TEB: Initiator: Chain transfer agent molar ratio; Mn b Number-average molecular weight, determined by gel permeation chromatography; PDI c Molecular weight distribution, determined by gel permeation chromatography.

[0044] Application Examples 28-34: Using the dual-active-center tetra-initiator B1 to initiate the copolymerization reaction of alkyl oxyoxide / phthalic anhydride / carbon dioxide

[0045] In a glove box, the dual-active-center tetra-initiator B1 and TEB, phthalic anhydride (PA), and other components were added to an autoclave in appropriate proportions. 0.01 mol of epoxide was added, and CO2 was introduced at 1 MPa. The reaction was carried out at 60°C for 3 hours. Afterward, carbon dioxide was released, and the reaction solution was analyzed by NMR to characterize the monomer conversion rate and product selectivity (the proportions of polycarbonate, polyether, and cyclic carbonate). The test results are shown in Table 4.

[0046] Table 4. Test results of initiator products in Application Examples 28-34

[0047] Among them, proportion a : Epoxyalkane: PA: TEB: Initiator molar ratio; M n b Number-average molecular weight, determined by gel permeation chromatography; PDI c Molecular weight distribution, determined by gel permeation chromatography.

[0048] Comparative Examples 1-7: PO / carbon dioxide copolymerization initiated by different initiators

[0049] In a glove box, different initiators, TEB, and phthalic anhydride (PA) were added to an autoclave in appropriate proportions, along with 0.01 mol of epoxide, and CO2 was introduced at 1 MPa. The reaction was carried out at 60°C for 4 h. Carbon dioxide was then released, and the reaction solution was analyzed by NMR to characterize the monomer conversion rate and product selectivity (the proportions of polycarbonate, polyether, and cyclic carbonate). The test results are shown in Table 5.

[0050] Table 5. Test results of initiator products of Comparative Examples 1–7

[0051] Among them, proportion a :PO:PA:TEB: Initiator molar ratio; M n b Number-average molecular weight, determined by gel permeation chromatography; PDI c Molecular weight distribution, determined by gel permeation chromatography.

Claims

1. A dual-active-center tetra-initiator, the structure of which is shown below: R1 is selected from H, halogens, and C1-C atoms with or without O, S, N, Si, or P atoms. 30 One of the alkyl groups; R2 is selected from C6-C atoms with or without O, S, N, and P atoms. 20 The aromatic group, wherein the substituents of the aromatic group are H, halogen, or no substituents, wherein the carboxyl group and the hydroxyl group are ortho-or ... 。 2. A method for preparing a dual-active-center tetra-initiator as described in claim 1, characterized in that... It is obtained by acid-base neutralization reaction of a tetrafunctional organic compound and an organic base; the molar ratio of the organic base to the difunctional organic compound is 2:

1.

3. The method for preparing the dual-active-center four-initiator according to claim 2, characterized in that... The tetrafunctional organic compounds are selected from the following structures: 。 4. The method for preparing the dual-active-center tetra-initiator according to claim 2, characterized in that... The inorganic anion is a hydroxide ion, and the organic base is a salt formed by an organic cation and an inorganic anion, wherein the organic cation is selected from the following structures: 。 5. The method for preparing the dual-active-center tetra-initiator according to claim 2, characterized in that... Includes the following steps: (1) Mix the tetrafunctional organic compound with the organic base and stir at room temperature until completely dissolved; (2) Stir the reaction mixture obtained in step (1) at 60°C for 3 hours; (3) Place the crude product of the dual-active-center tetra-initiator obtained in step (2) into a freeze-drying oven for freeze-drying treatment; (4) The crude product of the dual active center tetra-initiator obtained in step (3) is separated by filtration with acetone solution, washed to remove impurities, and finally vacuum dried to obtain the dual active center tetra-initiator.

6. The application of the dual-active-center tetra-initiator of claim 1 in the preparation of low molecular weight polymers or high molecular weight polymers.

7. The application as described in claim 6, characterized in that, Chain transfer agents can be added, and the amount of chain transfer agent is 0% to 10,000,000% of the molar number of the two active center tetra-initiator; the chain transfer agent is selected from one or more small or large molecular polymers containing amino groups, mercapto groups, hydroxyl groups, phenolic hydroxyl groups, and carboxyl groups, and having active hydrogen.

8. The application as described in claim 6, characterized in that, The low-molecular-weight polymer or high-molecular-weight polymer is an aliphatic polycarbonate obtained by copolymerizing carbon dioxide with epoxides, an aromatic polyester polycarbonate obtained by copolymerizing carbon dioxide with epoxides and phthalic anhydride, a polyether obtained by ring-opening polymerization of epoxides, a polythiocarbonate obtained by ring-opening polymerization of carbon dioxide with cyclothioalkanes, a polysulfide obtained by ring-opening of cyclic sulfides, a polyester obtained by catalytic ring-opening polymerization of epoxides and cyclic anhydrides, a polyester obtained by ring-opening polymerization of lactones, a polyester obtained by ring-opening of O-carboxylic anhydrides, or a polypeptide obtained by catalytic N-carboxylic anhydrides.

9. The application as described in claim 8, characterized in that, The epoxides, cyclothioalkylenes, cyclic anhydrides, and lactones are selected from the following structures: Among them, R1 and R2 are selected from H, halogens, and C1-C atoms with or without O, S, N, Si, and P atoms. 30 Alkyl, C3-C 30 cycloalkyl, C2-C 30 alkenyl, C2-C 30 alkynyl group, C6-C 30 Aromatic group, C3-C 30 One or more of heterocyclic groups; 。

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