Homogeneous nonmetal four-terminal initiator based on ion replacement reaction and preparation method thereof

Abstract

The invention discloses a homogeneous nonmetal four-terminal initiator based on ion replacement reaction and a preparation method of the homogeneous nonmetal four-terminal initiator. Through ion replacement reaction, organic cations are introduced into four-functionality organic metal salt molecules to form a homogeneous nonmetal four-terminal initiator. Compared with the traditional acid-base neutralization reaction method, the ion replacement reaction method provided by the invention has obvious advantages in solving the problems of low purity and difficult separation of the initiator. The homogeneous nonmetal four-terminal initiator prepared by an ion replacement reaction method not only shows excellent initiation capability and can play a key role in various polymerization reactions, but also shows excellent controllability in the polymerization process. In addition, the initiator is low in preparation raw material cost, simple in preparation process and convenient to operate, and has good industrial application potential.

Description

Technical Field

[0001] The invention belongs to the field of organic chemistry, and in particular relates to a homogeneous non-metallic four-terminal initiator based on ion replacement reaction and a preparation method thereof. Background Art

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

[0003] Although traditional anionic polymerization initiators, especially heterogeneous metal initiators, have achieved initial success in multiple polymerization reactions, they still have some problems that cannot be ignored in actual production and application. First, heterogeneous metal initiators usually rely on transition metals (such as titanium, aluminum, zirconium, cobalt, etc.) to achieve catalytic reactions. These transition metals have high catalytic activity in the reaction, but due to the particularity of their metallic properties and reaction mechanisms, these transition metals often induce side reactions during the reaction, resulting in a decrease in the selectivity of the polymerization reaction. In addition, contamination by metal residues often has a negative impact on the purity of the final product, especially in the preparation of high-performance polymers and pharmaceuticals, where metal residues often become a difficulty in achieving strict quality standards.

[0004] In recent years, homogeneous non-metallic initiators have gradually become a research hotspot. Homogeneous non-metallic initiators have low toxicity and high environmental friendliness. Since they do not contain metal elements, they can effectively avoid metal pollution problems. Especially in polymerization reactions, homogeneous non-metallic initiators can not only provide sufficient reaction activity, but also adjust the selectivity and molecular weight distribution of polymerization reactions by optimizing their molecular structure, thereby improving the performance of polymers.

[0005] Among many homogeneous non-metallic initiators, quadruple-terminal initiators have become a research focus due to their unique structure. Quadruple-terminal initiators provide multiple reaction sites by introducing multiple terminal groups. This structural characteristic enables quadruple-terminal initiators to provide higher reactivity during the reaction process. In addition, the initiation ability of quadruple-terminal initiators can be further improved by rationally designing the molecular structure, so that they can show good applicability and high efficiency in different polymerization reactions.

[0006] At present, the conventional preparation method of four-terminal initiators mainly relies on acid-base neutralization reaction. The required four-terminal initiator is generated by neutralization of acidic and basic compounds. In theory, this method can meet the synthesis requirements of initiators. However, in actual operation, the acid-base neutralization method has some significant problems: 1. Product purity problem: During the purification process of the initiator, freeze-drying will lead to the occurrence of double hydrolysis reaction, which will cause acidic and basic compounds to mix into the initiator. The uncontrollability of this hydrolysis reaction, especially between different batches, leads to large fluctuations in the purity of the final product. Moreover, the degree of hydrolysis reaction is difficult to accurately control, so it is difficult to ensure the accuracy of the synthesized initiator structure, which affects the repeatability and stability of its performance.

[0007] 2. Imbalance in reaction ratio: In the acid-base neutralization reaction, the ratio of the reactant acid to the base is crucial to the completeness of the reaction. If the acid-base ratio is not accurately controlled in actual operation, it may lead to incomplete reaction and generate undesirable intermediates or by-products. These by-products will not only reduce the purity of the product, but may also have an adverse effect on the subsequent polymerization reaction or final application.

[0008] 3. Reaction endpoint control problem: Although acid-base neutralization reactions are usually rapid, it is still a challenge to accurately control the reaction endpoint in actual processes, especially in large-scale production. If the reaction is not completely neutralized or is over-neutralized, the properties of the final product will deviate from expectations, thereby affecting its application performance. Therefore, how to accurately grasp the reaction endpoint in large-scale production is the key to ensuring product quality and consistency.

[0009] Therefore, in order to achieve efficient and stable synthesis of quadruple-terminal initiators in industrial production, it is urgent to develop new synthesis methods with higher precision and controllability to improve product purity, reduce by-product generation, and ensure the stability of the reaction process. This will be an important direction for future research. Summary of the invention

[0010] The purpose of the present invention is to improve some core problems faced by traditional heterogeneous metal initiators and existing acid-base neutralization methods for preparing homogeneous non-metallic four-terminal initiators. The present invention proposes a homogeneous non-metallic four-terminal initiator based on ion exchange reaction and a preparation method thereof. This innovation not only provides a new choice for replacing traditional heterogeneous metal initiators, but also provides an effective solution for promoting efficient and green synthesis of polymerization reactions. Compared with traditional metal-based initiators, homogeneous non-metallic initiators show better controllability and purity during the reaction process, while avoiding environmental pollution and by-product generation problems that may be caused by metal initiators. The present invention not only has far-reaching theoretical significance, promotes the understanding of initiator design and polymerization reaction mechanism, but also has broad prospects in practical applications. In particular, in the fields of polymer synthesis, green chemical process and development of environmentally friendly materials, the potential and application value of homogeneous non-metallic four-terminal initiators are particularly prominent. The promotion of this technology can improve product quality and reduce production costs while also providing new ideas and methods for achieving more environmentally friendly and sustainable material synthesis. Therefore, the present invention has great academic value and practical application prospects.

[0011] First of all, traditional heterogeneous metal initiators usually rely on transition metals (such as titanium, aluminum, zirconium, cobalt, etc.) to achieve catalytic reactions. Due to their metallic properties and special reaction mechanisms, these metals often induce side reactions and reduce the selectivity of polymerization reactions. In addition, the pollution problem of metal residues is particularly prominent in the fields of high-performance polymers and medicine. Their application is greatly restricted, and there is an urgent need to develop new, more efficient and environmentally friendly initiator systems.

[0012] Secondly, the current synthesis method of homogeneous non-metallic four-terminal initiators mainly relies on the acid-base neutralization method. In practical applications, especially in the purification stage, it is often faced with problems such as difficulty in product separation and low purity, which seriously restricts its promotion and application in industrial large-scale production. In order to solve these practical problems, the present invention proposes a novel homogeneous non-metallic four-terminal initiator and its preparation method based on ion exchange reaction. This innovation not only effectively avoids the side reactions and metal pollution problems caused by traditional heterogeneous metal initiators, but also breaks through the bottleneck encountered by the acid-base neutralization method in the preparation process, and provides a more efficient and simpler solution for the purification process. By adopting the ion exchange reaction, the present method can significantly improve the purity and stability of the product while ensuring the selectivity of the reaction, thereby providing a practical technical path for large-scale industrial production.

[0013] In order to achieve the above object, the present invention adopts the following technical solution: A homogeneous non-metallic four-terminal initiator based on ion exchange reaction is obtained by ion exchange reaction of a tetrafunctional organic metal salt and an organic salt, wherein the tetrafunctional organic metal salt is obtained by reaction of a tetrafunctional organic compound and an inorganic salt.

[0014] Preferably, the molar ratio of the inorganic salt to the tetrafunctional organic compound is (1-4):1; the molar feed ratio of the inorganic salt to the organic salt is 1:(1-3).

[0015] Preferably, the tetrafunctional organic compound is selected from the following structures:

[0016] Preferably, the inorganic salt is potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium phosphate, sodium phosphate, potassium bicarbonate or sodium bicarbonate.

[0017] Preferably, the organic salt is a salt substance formed by an organic cation and an inorganic anion, and the organic cation is selected from the following structures:

[0018] The inorganic anion is a chloride ion or a bromide ion.

[0019] A method for preparing the homogeneous non-metallic four-terminal initiator based on ion exchange reaction comprises the following steps: (1) dissolving the inorganic salt in distilled water, adding the tetrafunctional organic compound after the inorganic salt is completely dissolved, and stirring at room temperature until the tetrafunctional organic compound is completely dissolved; (2) slowly pouring the reaction mixture obtained in step (1) into an acetone solution, filtering and separating the generated white precipitate, and washing with an ether solution to remove impurities, thereby obtaining a tetrafunctional organic metal salt; (3) placing the tetrafunctional organic metal salt in a vacuum drying oven for vacuum drying; (4) A tetrafunctional organometallic salt, an organic salt and distilled water are sequentially added into a flask and stirred at room temperature to cause an ion exchange reaction. The generated white precipitate is first separated by filtration, then washed with water and acetone solution in sequence to remove impurities, and finally dried in vacuum to obtain a homogeneous non-metallic four-terminal initiator.

[0020] Compared with the prior art, the present invention has the following beneficial effects: (1) Avoiding the side reactions and pollution problems of heterogeneous metal initiators: The present invention adopts a homogeneous non-metallic four-terminal initiator, which avoids the side reactions and metal residue pollution problems caused by traditional heterogeneous metal initiators, improves the activity and selectivity of the polymerization reaction, and is particularly suitable for applications in the fields of high-performance polymers and medicine that have strict purity requirements.

[0021] (2) Improved product purity and reaction stability: Compared with the traditional acid-base neutralization method, the present invention based on ion exchange reaction can effectively avoid separation difficulties, low purity and other problems, ensure the high purity of the initiator and the stability of the reaction, and has better prospects for industrial application.

[0022] (3) 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.

[0023] (4) Providing a green and environmentally friendly alternative: The homogeneous non-metallic initiator of the present invention not only has low toxicity and meets 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 wide application potential, especially in the development of polymer synthesis and environmentally friendly materials, showing great scientific research and industrial value. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] The accompanying drawings are intended to further clearly illustrate and explain the technical solutions and embodiments of the present invention, and do not constitute a limitation of the present invention. In the accompanying drawings: Figure 1 The H NMR spectrum of the homogeneous non-metallic four-terminal initiator was prepared by ion replacement reaction.

[0025] Figure 2 The H NMR spectrum of the homogeneous non-metallic four-terminal initiator was prepared by traditional acid-base neutralization reaction. DETAILED DESCRIPTION

[0026] The present invention can be further explained and illustrated in conjunction with the following specific examples, but the specific examples do not limit the present invention in any form. Embodiment 1:

[0027] First, weigh 0.04 mol of sodium hydroxide and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of pyromellitic acid and stir at room temperature 25°C for 2 hours until the pyromellitic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0028] The product obtained in the first step, 0.04 mol tetrabutylammonium chloride and 30 mL distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 2:

[0029] First, weigh 0.04 mol of sodium bicarbonate and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of pyromellitic acid and stir at room temperature 25°C for 2 hours until the pyromellitic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0030] The product obtained in the first step, 0.04 mol tetrabutylammonium chloride and 30 mL distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 3:

[0031] First, weigh 0.02 mol of sodium carbonate and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of pyromellitic acid and stir at room temperature (25°C) for 2 hours until the pyromellitic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0032] The product obtained in the first step, 0.04 mol tetrabutylammonium chloride and 30 mL distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 4:

[0033] First, weigh 0.02 mol of potassium carbonate and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of tetrabutanecarboxylic acid and stir at room temperature (25°C) for 2 hours until the tetrabutanecarboxylic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with an ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0034] The product obtained in the first step, 0.04 mol of tetraphenylphosphine bromide and 30 mL of distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 5:

[0035] First, weigh 0.04 mol of potassium hydroxide and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of tetrahydroxyphenol and stir at room temperature (25°C) for 2 hours until the tetrahydroxyphenol is completely dissolved. After the reaction is completed, slowly pour the reaction solution into the acetone solution, and the generated white precipitate is separated by filtration. Then, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0036] The product obtained in the first step, 0.04 mol of bis(triphenylphosphoryl)ammonium chloride and 30 mL of distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 6:

[0037] First, weigh 0.02 mol of sodium carbonate and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of tetrabutanecarboxylic acid and stir at room temperature (25°C) for 2 hours until the tetrabutanecarboxylic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0038] The product obtained in the first step, 0.04 mol tetrabutylammonium bromide and 30 mL distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator. Embodiment 7:

[0039] First, weigh 0.04 mol of sodium hydroxide and dissolve it in 20 mL of distilled water. Then, add 0.01 mol of 3,3',5,5'-biphenyltetracarboxylic acid and stir at room temperature (25°C) for 2 hours until 3,3',5,5'-biphenyltetracarboxylic acid is completely dissolved. After the reaction is completed, slowly pour the reaction solution into an acetone solution, and the generated white precipitate is separated by filtration. Next, wash the precipitate with ether solution. After washing 2 to 3 times, transfer the product to a vacuum drying oven at 80°C for vacuum drying until it is completely dry.

[0040] The product obtained in the first step, 0.04 mol tetrabutylammonium bromide and 30 mL distilled water were added to a 100 mL single-necked flask in sequence, and the reaction system was stirred at room temperature at 25°C for 2 hours to promote the ion exchange reaction. After the reaction was completed, the generated white precipitate was filtered and washed 2 to 3 times with water and acetone solution respectively. Finally, the washed product was transferred to a vacuum drying oven at 80°C for vacuum drying to finally obtain a homogeneous non-metallic four-terminal initiator.

[0041] Comparative Example 1: Preparation of a homogeneous non-metallic four-terminal initiator using the traditional acid-base neutralization method First, accurately weigh 0.04 mol of tetrabutylammonium hydroxide aqueous solution and add it to a 100 mL single-necked flask. Then, add 0.01 mol of pyromellitic acid. The reaction system was stirred at 60°C for 2 hours until the solution became transparent and the pH value was close to 7, indicating that the reaction was nearly complete. At this point, the reaction was stopped. After the reaction was completed, the obtained transparent solution was transferred to a freeze drying oven and freeze-dried for 48 hours to remove moisture. Subsequently, in order to further remove moisture, the solution was transferred to the front chamber in the glove box and further dehydrated by phosphonic anhydride. Finally, a homogeneous non-metallic four-terminal initiator product was obtained.

[0042] Figure 1 This is the H NMR spectrum of the homogeneous non-metallic four-terminal initiator prepared by ion exchange reaction in Example 1 of the present invention. Figure 2 This is the H NMR spectrum of the homogeneous non-metallic four-terminal initiator prepared by traditional acid-base neutralization reaction in Comparative Example 1.

[0043] pass Figure 1 and Figure 2 It can be seen from the comparison of the above-mentioned synthesis methods that the acid-base neutralization method has the problems of low product purity and difficult separation. This not only increases the complexity of the purification step, but also may cause the residue of impure substances, thereby affecting the quality of the final polymer and the stability of the polymerization reaction. The ion exchange reaction method of the present invention effectively avoids these problems and ensures the high purity and consistency of the initiator. The advantages of this initiator synthesis method based on ion exchange reaction are not only reflected in laboratory-scale synthesis, but also show great potential in large-scale industrial production.

Claims

1. A homogeneous non-metallic four-terminal initiator based on ion exchange reaction, characterized in that The tetrafunctional organic metal salt is obtained by ion replacement reaction between a tetrafunctional organic metal salt and an organic salt. The tetrafunctional organic metal salt is obtained by reaction between a tetrafunctional organic compound and an inorganic salt.

2. The homogeneous non-metallic four-terminal initiator based on ion exchange reaction according to claim 1, characterized in that The molar ratio of the inorganic salt to the tetrafunctional organic compound is (1-4):1; the molar feed ratio of the inorganic salt to the organic salt is 1:(1-3).

3. The homogeneous non-metallic four-terminal initiator based on ion exchange reaction according to claim 1, characterized in that The tetrafunctional organic compound is selected from the following structures: 。 4. The homogeneous non-metallic four-terminal initiator based on ion exchange reaction according to claim 1, characterized in that The inorganic salt is potassium hydroxide, sodium hydroxide, potassium carbonate, sodium carbonate, potassium phosphate, sodium phosphate, potassium bicarbonate or sodium bicarbonate.

5. The homogeneous non-metallic four-terminal initiator based on ion exchange reaction according to claim 1, characterized in that The organic salt is a salt substance formed by an organic cation and an inorganic anion, and the organic cation is selected from the following structures: 。 6. A method for preparing a homogeneous non-metallic four-terminal initiator based on ion exchange reaction as claimed in claim 1, characterized in that The following steps are involved: (1) dissolving the inorganic salt in distilled water, adding the tetrafunctional organic compound after the inorganic salt is completely dissolved, and stirring at room temperature until the tetrafunctional organic compound is completely dissolved; (2) slowly pouring the reaction mixture obtained in step (1) into an acetone solution, filtering and separating the generated white precipitate, and washing with an ether solution to remove impurities, thereby obtaining a tetrafunctional organic metal salt; (3) placing the tetrafunctional organic metal salt in a vacuum drying oven for vacuum drying; (4) A tetrafunctional organometallic salt, an organic salt and distilled water are sequentially added into a flask and stirred at room temperature to cause an ion exchange reaction. The generated white precipitate is first separated by filtration, then washed with water and acetone solution in sequence to remove impurities, and finally dried in vacuum to obtain a homogeneous non-metallic four-terminal initiator.

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