Crown ether-containing aromatic dicarboxylic acid and method for preparing the same
A simplified two-step method for synthesizing crown-ether aromatic dicarboxylic acids solves the problems of complex synthesis routes and high costs in existing technologies, achieving high-purity and high-yield target products suitable for the preparation of high-performance functional materials.
Patent Information
- Application Number
- CN202511949048.1
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Filing Date
- 2025-12-23
- Publication Date
- 2026-07-10
AI Technical Summary
Existing synthetic routes for crown ether functional monomers are complex and costly, limiting their application in the preparation of functional materials. Furthermore, the variety of these monomers is limited, making it difficult to meet the needs of large-scale production.
A two-step method for synthesizing crown ether aromatic dicarboxylic acids, including acetylation and oxidation steps, is adopted. The reaction is carried out in a low-boiling organic solvent and a specific alkaline environment, avoiding complex purification steps. The synthesis process is simplified by using rotary evaporation, washing, vacuum drying and recrystallization.
It improves product purity and yield, reduces the probability of side reactions, is suitable for large-scale production, meets the purity requirements of high-performance materials, expands the flexibility of molecular structure, and adapts to the performance requirements of different functional materials.
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Figure CN122356007A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of organic synthesis technology, specifically to a crown ether aromatic dicarboxylic acid and its preparation method. Background Technology
[0002] Crown ethers are cyclic polyether skeletons containing repeating oxygen-methylene (-CH2-) units. The spacing between their oxygen atoms can form specific vacancies, exhibiting selectivity for alkali metal and alkaline earth metal ions. For example, the 15-crown-5 structure contains 5 oxygen atoms, with vacancies approximately 0.17-0.22 nm in diameter, exhibiting strong complexing ability for sodium ions; the 18-crown-6 structure contains 6 oxygen atoms, with vacancies approximately 0.26-0.32 nm in diameter, exhibiting high selectivity for potassium ions. Due to their spatial structure and unique ion complexing ability, crown ethers have shown broad application value in rare earth element separation, ion adsorption materials, metal ion sensors, and the preparation of functional polymers. For example, studies have used bis(aminophenyl)-18-crown-6 as a monomer to prepare porous polyimide membranes, which exhibit good adsorption capacity for strontium ions (Journal of Radioanalytical and NuclearChemistry (2023) 332:5051–5057). Crown-ether-containing copolyimides have also been used in gas separation membranes, demonstrating good CO2 permeability and CO2 / N2 selectivity (Journal of Membrane Science 551 (2018) 191–203). However, the synthetic route for this crown-ether-containing amino monomer is long, complex, and expensive, which is not conducive to commercial production. Currently, crown-ether-containing functional monomers are monopolized by foreign countries, and the types available are still limited, restricting the application of crown ethers in the preparation of special materials. Therefore, there is an urgent need to develop crown-ether-containing dicarboxylic acid monomers with simple routes, high yields, high purity, and mass production capabilities, which can have outstanding application value in the preparation of functional materials such as polyesters, polybenzimidazoles, and polybenzothiazoles. Summary of the Invention
[0003] Technical problems to be solved To address the shortcomings of existing technologies, this invention provides a crown-ether aromatic dicarboxylic acid and its preparation method. This two-step synthesis method eliminates complex purification steps, significantly reducing reaction time. Furthermore, the product exhibits high purity and high yield, making it suitable for large-scale production.
[0004] Technical solution
[0005] To achieve the above objectives, the present invention provides the following technical solution: a method for preparing a crown-ether aromatic dicarboxylic acid, wherein the synthesis of the prepared crown-ether aromatic dicarboxylic acid comprises two steps: acetylation of the aromatic crown ether and oxidation of the acetyl group: (1) Synthesis of acetyl aromatic crown ethers As shown in Formula 2, the acetyl aromatic crown ether B is obtained by using aromatic crown ether A and acetyl chloride as raw materials and a low-boiling-point organic solvent as the reaction solvent. The acetylation solvent used in step (1) is any one or at least a combination of two of dichloromethane, trichloromethane, tetrahydrofuran and trifluoroacetic acid. AB Formula 2 (2) Synthesis of aromatic crown ether dicarboxylic acids As shown in Formula 3, the aromatic crown ether dicarboxylic acid C is prepared by reacting acetyl aromatic crown ether B, sodium hydroxide, liquid bromine, and 1,4-dioxane; the acetylation reagent used in step (2) is acetyl chloride.
[0006] BC Formula 3 Further, in Formula 2, n takes values ranging from 4 to 10, and Ar1 is selected from any one of the crown ether groups of Formula 4, whether substituted or unsubstituted: the benzene ring is connected to two methylene positions adjacent to any crown ether.
[0007] Formula 4 Furthermore, in Formula 2, Ar2 is selected from one or more of substituted or unsubstituted H, halogen, -OH, -SO3, -NO2, -H2PO4, and -NH2.
[0008] Further, in step (1), the molar ratio of aromatic crown ether to acetyl chloride is 1:2-1:10.
[0009] Further, in step (1), the solid content of the aromatic crown ether in dichloromethane, trichloromethane, tetrahydrofuran and trifluoroacetic acid is 5-60%.
[0010] Further, in step (1), after the aromatic crown ether compound is mixed evenly with the solvent, acetyl chloride is added to react; The mixing temperature is 0-20℃; The reaction temperature is 20-40℃; The reaction time is 12-24 hours. The acetyl chloride is added dropwise.
[0011] Furthermore, after the first step reaction described in step (1), only the organic solvent needs to be evaporated by rotary evaporation, without the need for complex purification steps.
[0012] Further, the oxidizing environment in step (2) is an alkaline environment; the alkaline environment in step (2) is an aqueous solution of sodium hydroxide, and the solid content of sodium hydroxide in the aqueous solution is 10-30%; the oxidizing reagent selected in step (2) is liquid bromine; the molar ratio of the acetylated aromatic crown ether selected in step (2) to 1,4-dioxane is 1:0-1:50, and the molar ratio of the acetylated aromatic crown ether to liquid bromine is 1:4-1:40; the solid content of the acetylated aromatic crown ether selected in step (2) is 5-80%.
[0013] Furthermore, the preparation method includes: dispersing acetylated aromatic crown ether in a solution of sodium hydroxide and 1,4-dioxane, followed by slow dropwise addition of liquid bromine for reaction; The mixing temperature is -15 to 25°C; The reaction temperature is -15 to 30°C; The reaction time is 12-24 hours. The liquid bromine is added dropwise.
[0014] Furthermore, the reaction also includes a post-processing step: The post-processing includes washing, filtering, drying, and recrystallization; The drying method described is vacuum drying; The recrystallization reagent includes any one or a combination of at least two of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide or N,N-dimethylacetamide and chloroform.
[0015] Beneficial technical effects This invention employs a precise two-step reaction involving acetylation and oxidation, with organic solvents removed via rotary evaporation in between. This eliminates the need for complex purification steps. Purification is achieved through washing, filtration, vacuum drying, and specific recrystallization reagents, resulting in a high-purity final product that effectively reduces the interference of impurities in subsequent applications. The reaction conditions are mild and controllable, ensuring stable yields of the target product and meeting the stringent purity requirements for monomers in the preparation of high-performance materials. Ar1 in the product can be selected from substituted or unsubstituted crown ether groups with different crown numbers (n=4-10), while Ar2 can be flexibly combined with various substituents such as H, halogens, -OH, and -SO3. The molecular structure can be adjusted according to specific application scenarios to adapt to the performance requirements of different functional materials, overcoming the limitations of existing single-structure crown ether monomers. The invention retains the unique cyclic polyether skeleton and ion-complexing ability of crown ethers while introducing reactive sites from aromatic dicarboxylic acids. This allows the product to selectively complex alkali metal and alkaline earth metal ions and participate in the polymerization of high-performance polymers such as polyesters, polyamides, and polybenzimidazoles through the carboxylic acid groups, providing core support for the structural design and performance optimization of functional materials. This invention requires only two core reactions: acetylation and acetylation. With fewer steps and a shorter process, it avoids the problems of lengthy synthesis routes and complex intermediate products in traditional crown ether monomer synthesis, significantly reducing the probability of side reactions and improving production efficiency. Attached Figure Description
[0016] Figure 1 It is the structure of Equation 1.
[0017] Figure 2 This is the liquid nuclear magnetic resonance (NMR) spectrum of the purified acetyl aromatic crown ether in Example 2 of this invention.
[0018] Figure 3 This is the liquid NMR spectrum of the purified dicarboxylic aromatic crown ether in Example 2 of the present invention. Detailed Implementation
[0019] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.
[0020] To better understand the above technical solutions, the following will provide a detailed explanation of the technical solutions in conjunction with the accompanying drawings and specific embodiments.
[0021] Example 1 This embodiment provides an aromatic crown ether dicarboxylic acid D2, the synthetic route of which is shown in the following formula.
[0022] D D1 D2 Using a mechanical stirrer, 20 mmol of aromatic crown ether compound D was placed in a three-necked flask, 30 mL of dichloromethane was added and stirred, and then 80 mmol of acetyl chloride was slowly added dropwise. The reaction was carried out at 25 °C for 12 h. After the reaction was completed, the crude acetylated aromatic crown ether product was obtained. The product was washed with deionized water and ethanol, recrystallized and purified, and dried to obtain acetylated aromatic crown ether D1. Under ice-water bath conditions, 10 mmol of acetylated aromatic crown ether D1 was placed in a three-necked flask, deionized water and sodium hydroxide solution were added, and the mixture was stirred for 2 h. Then, 40 mmol of liquid bromine and 50 mmol of 1,4-dioxane were slowly added dropwise and the reaction was carried out at 30 °C for 12 h. After washing and recrystallization purification, the product D2 containing aromatic crown ether carboxylic acid was obtained.
[0023] Example 2 This embodiment provides an aromatic crown ether dicarboxylic acid E2, the synthetic route of which is shown in the following formula.
[0024] E E1 E2 Using a mechanical stirrer, 30 mmol of aromatic crown ether compound E was placed in a three-necked flask, 60 mL of chloroform was added and stirred, and then 120 mmol of acetyl chloride was slowly added dropwise. The reaction was carried out at 25 °C for 24 h. After the reaction was completed, the crude acetylated aromatic crown ether product was obtained. The product was washed with deionized water and ethanol, recrystallized and purified, and dried to obtain acetylated aromatic crown ether E1. Under ice-water bath conditions, 15 mmol of acetylated aromatic crown ether E1 was placed in a three-necked flask, sodium hydroxide aqueous solution was added, and after stirring, 70 mmol of liquid bromine and 100 mmol of 1,4-dioxane were slowly added dropwise. The reaction was carried out at 30 °C for 24 h. After washing and recrystallization purification, the product E2 containing aromatic crown ether carboxylic acid was obtained.
[0025] Example 3 This embodiment provides an aromatic crown ether dicarboxylic acid F2, the synthetic route of which is shown in the following formula.
[0026] F F1 F2 Using a mechanical stirrer, 30 mmol of aromatic crown ether compound F was placed in a three-necked flask, 80 mL of chloroform was added and stirred, and then 150 mmol of acetyl chloride was slowly added dropwise. The reaction was carried out at 30 °C for 24 h. After the reaction was completed, the crude acetylated aromatic crown ether product was obtained. The product was washed with deionized water and ethanol, recrystallized and purified, and dried to obtain acetylated aromatic crown ether F1. Under ice-water bath conditions, 20 mmol of acetylated aromatic crown ether F1 was placed in a three-necked flask, sodium hydroxide aqueous solution was added, and after stirring, 100 mmol of liquid bromine was slowly added dropwise. The reaction was carried out at 20 °C for 24 h. After washing and recrystallization purification, the product F2 containing aromatic crown ether carboxylic acid was obtained.
[0027] Example 4 This embodiment provides a dicarboxylic acid G2 containing an aromatic crown ether, and its synthetic route is shown in the following formula.
[0028] G G1 G2 Using a mechanical stirrer, 30 mmol of aromatic crown ether compound G was placed in a three-necked flask, 70 mL of dichloromethane was added and stirred, and then 120 mmol of acetyl chloride was slowly added dropwise. The reaction was carried out at 25 °C for 18 h. After the reaction was completed, the crude acetylated aromatic crown ether product was obtained. The product was washed with deionized water and ethanol, recrystallized and purified, and dried to obtain acetylated aromatic crown ether E1. Under ice-water bath conditions, 15 mmol of acetylated aromatic crown ether G1 was placed in a three-necked flask, sodium hydroxide aqueous solution was added, and after stirring, 70 mmol of liquid bromine and 100 mmol of 1,4-dioxane were slowly added dropwise. The reaction was carried out at 30 °C for 18 h. After washing and recrystallization purification, the product G2 containing aromatic crown ether carboxylic acid was obtained.
[0029] Example 5 This embodiment provides a dicarboxylic acid H2 containing an aromatic crown ether, and its synthetic route is shown in the following formula.
[0030] H H1 H2 Using a mechanical stirrer, 20 mmol of aromatic crown ether compound H was placed in a three-necked flask, 100 mL of tetrahydrofuran was added and stirred, and then 200 mmol of acetyl chloride was slowly added dropwise. The reaction was carried out at 20 °C for 12 h. After the reaction was completed, the crude acetylated aromatic crown ether product was obtained. The product was washed with deionized water and ethanol, recrystallized and purified, and dried to obtain acetylated aromatic crown ether H1. Under ice-water bath conditions, 20 mmol of acetylated aromatic crown ether H1 was placed in a three-necked flask, sodium hydroxide aqueous solution was added, and after stirring, 180 mmol of liquid bromine was slowly added dropwise. The reaction was carried out at 10 °C for 18 h. After washing and recrystallization purification, the product H2 containing aromatic crown ether carboxylic acid was obtained.
[0031] Comparative Example 1: The low-boiling-point organic solvent chloroform used in the first step of Example 2 was replaced with the high-boiling-point organic solvent N,N-dimethylformamide. The same process was performed for acetylation and subsequent oxidation. The results showed that the solvent evaporation was slow, the subsequent reaction failed, and the target product was not obtained. Comparative Example 1 illustrates the advantages and applicability of low-boiling-point organic solvents in the preparation of aromatic dicarboxylic acid crown ethers.
[0032] It should be noted that, in this document, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising one..." does not exclude the presence of other identical elements in the process, method, article, or apparatus that includes said element.
[0033] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.
[0034] Those skilled in the art should understand that the above descriptions are merely several specific embodiments of the present invention, and not all embodiments.
Claims
1. A method for preparing a crown ether aromatic dicarboxylic acid, characterized in that, The synthesis of the crown-ether aromatic dicarboxylic acid prepared comprises two steps: acetylation of the aromatic crown ether and oxidation of the acetyl group. (1) Synthesis of acetyl aromatic crown ethers As shown in Formula 2, the acetyl aromatic crown ether B is obtained by using aromatic crown ether A and acetyl chloride as raw materials and a low-boiling-point organic solvent as the reaction solvent. The acetylation solvent used in step (1) is any one or at least a combination of two of dichloromethane, trichloromethane, tetrahydrofuran and trifluoroacetic acid. AB Formula 2 (2) Synthesis of aromatic crown ether dicarboxylic acids As shown in Formula 3, the aromatic crown ether dicarboxylic acid C is prepared by reacting acetyl aromatic crown ether B, sodium hydroxide, liquid bromine, and 1,4-dioxane; the acetylation reagent used in step (2) is acetyl chloride; BC Formula 3.
2. The method for preparing crown-ether aromatic dicarboxylic acids according to claim 1, characterized in that, In Formula 2, n ranges from 4 to 10, and Ar1 is selected from any one of the crown ether groups of Formula 4, whether substituted or unsubstituted: the benzene ring is connected to the two methylene positions adjacent to any crown ether. Formula 4.
3. The method for preparing crown-ether aromatic dicarboxylic acids according to claim 1, characterized in that, In Formula 2, Ar2 is selected from one or more of substituted or unsubstituted H, halogen, -OH, -SO3, -NO2, -H2PO4, and -NH2.
4. The method for preparing crown-ether aromatic dicarboxylic acids as described in claim 1, characterized in that, Step (1) The molar ratio of aromatic crown ether to acetyl chloride is 1:2-1:
10.
5. The method for preparing crown-ether aromatic dicarboxylic acids as described in claim 1, characterized in that, Step (1) The solid content of aromatic crown ether in dichloromethane, trichloromethane, tetrahydrofuran and trifluoroacetic acid is 5-60%.
6. The method for preparing crown-ether aromatic dicarboxylic acids according to claim 1, characterized in that, Step (1) After the aromatic crown ether compound is mixed evenly with the solvent, acetyl chloride is added to react; The mixing temperature is 0-20℃; The reaction temperature is 20-40℃; The reaction time is 12-24 hours. The acetyl chloride is added dropwise.
7. The method for preparing crown-ether aromatic dicarboxylic acids according to claim 1, characterized in that, The organic solvent in step (1) is removed by rotary evaporation after the first reaction, without a complicated purification process.
8. The method for preparing crown-ether aromatic dicarboxylic acids according to claim 1, characterized in that, The oxidizing environment described in step (2) is an alkaline environment; the alkaline environment described in step (2) is an aqueous solution of sodium hydroxide, and the solid content of sodium hydroxide in the aqueous solution is 10-30%; the oxidizing reagent selected in step (2) is liquid bromine; the molar ratio of the acetylated aromatic crown ether selected in step (2) to 1,4-dioxane is 1:0-1:50, and the molar ratio of the acetylated aromatic crown ether to liquid bromine is 1:4-1:40; the solid content of the acetylated aromatic crown ether selected in step (2) is 5-80%.
9. The preparation method according to any one of claims 1-8, characterized in that, The preparation method includes: dispersing acetylated aromatic crown ethers in a solution of sodium hydroxide and 1,4-dioxane, followed by slow dropwise addition of liquid bromine for reaction; The mixing temperature is -15 to 25°C; The reaction temperature is -15 to 30°C; The reaction time is 12-24 hours. The liquid bromine is added dropwise.
10. The preparation method according to claims 1-9, characterized in that, The reaction also includes a post-processing step: The post-processing includes washing, filtering, drying, and recrystallization; The drying method described is vacuum drying; The recrystallization reagent includes any one or a combination of at least two of dimethyl sulfoxide, N-methylpyrrolidone, N,N-dimethylformamide or N,N-dimethylacetamide and chloroform.