Air-stable cyclopropene imine organic boron dual-work catalyst as well as preparation method and application of air-stable cyclopropene imine organic boron dual-work catalyst
By combining cyclopropyleneimine with borane to form a B-N coordination catalyst, the problem of air instability of the organic boron catalyst is solved, air stability and efficient catalytic activity are achieved, and it is suitable for the synthesis of small organic molecules and polymers.
Patent Information
- Application Number
- CN202510283924.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-11
- Publication Date
- 2025-07-22
AI Technical Summary
The existing organic boron catalysts are unstable in the air, limiting their application in actual storage and use, and metal catalysts have problems such as metal contamination and sensitivity to water and impurities.
The cyclopropyleneimine is combined with borane to form an air-stable cyclopropyleneimine organic boron bifunctional catalyst through B-N coordination. The preparation method includes mixing and reacting under an inert atmosphere, and then deprotonating to obtain the catalyst.
The catalyst remains stable in air, exhibits excellent catalytic activity, and can accurately control the end groups and synthetic topology of the polymer, improving the practicality and application range of the catalyst.
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Figure CN120349334A_ABST
Abstract
Description
Technical Field
[0001] The present invention belongs to the technical field of compound preparation, and particularly relates to an air-stable cyclopropenimine organoboron bifunctional catalyst, a preparation method thereof, and an application thereof. Background Art
[0002] Metal catalysts play an important role in polymerization reactions because they usually have high catalytic activity, good monomer adaptability, and the ability to precisely control the polymerization rate. In particular, transition metal catalysts have shown unique advantages in controlling the stereoregularity, molecular weight, and distribution of polymers, making them widely used in the synthesis of polyolefins, polyesters, and epoxy polymers (Chem. Commun., 2015, 51, 6459 - 6479). However, metal catalysts also have some limitations. For example, catalyst residues may cause metal contamination of polymer products, affecting the biocompatibility and optoelectronic properties of materials. In addition, metal catalysts are usually sensitive to water and impurities, posing challenges in actual industrial production and bio-related applications. In contrast, organic catalysts have received extensive attention in recent years due to their low metal residue risk, environmental friendliness, and good functional group tolerance. Especially in the field of polymer synthesis, developing efficient, highly selective, and environmentally sustainable organic catalytic systems is of great significance. For example, organic catalytic strategies based on hydrogen bonding, base catalysis, or Lewis acid-base interactions can achieve efficient polymerization under mild conditions and have good structural tunability (Macromolecules 2010, 43, 2093–2107; Prog. Polym. Sci. 2016, 56, 64 - 115). With the increasing demand for degradable and functionalized polymer materials, the development of organic catalysts not only provides a green alternative to metal catalytic systems but also offers new opportunities for fine tuning of polymer structures.
[0003] Catalysts integrating Lewis acidic boron centers with ammonium salts or phosphonium salts have shown good performance in polymer synthesis, which is a good strategy for designing organic catalysts. However, common ionic salt organoboron catalysts still have the defect of poor air tolerance (Angew. Chem. Int. Ed. 2024, 63, e202318645). This instability limits their application in actual storage and use. Therefore, it is particularly important to develop catalysts with higher air stability while retaining the advantages of traditional organoboron catalysts. Summary of the Invention
[0004] To solve the defects and deficiencies existing in the prior art, the primary object of the present invention is to provide a cyclopropenimine organoboron bifunctional catalyst.
[0005] Another object of the present invention is to provide the above-mentioned cyclopropenimine organoboron bifunctional catalyst. The present invention combines cyclopropenimine with borane, and due to the B-N coordination between them, this type of catalyst is endowed with excellent air stability, greatly improving the practicality of this type of catalyst.
[0006] Another object of the present invention is to also provide the application of the above-mentioned cyclopropenimine organoboron bifunctional catalyst.
[0007] To achieve the above object, the present invention adopts the following technical solutions:
[0008] A cyclopropenimine organoboron bifunctional catalyst, the chemical structural formula of the catalyst is as follows:
[0009]
[0010] In formula A, the substituents R1, R2, R3, and R4 are the same or different and are selected from hydrogen, alkyl (preferably C1-C50 alkyl, more preferably C3-C15 alkyl) or aryl, wherein the substituents R1 and R2 are covalently cyclized or not cyclized, and R3 and R4 are covalently cyclized or not cyclized; is borane, including acyclic borane and cyclic borane; wherein, n is an integer from 1 to 50.
[0011] Preferably, the borane is one of acyclic borane and cyclic borane.
[0012] Preferably, the groups formed by the substituents R1, R2, R3, and R4 after being connected to nitrogen are the same or different and are selected from the following structures:
[0013]
[0014] wherein, n and m are integers from 1 to 50.
[0015] Preferably, the borane part is selected from the following structures:
[0016]
[0017] Preferably, the distance interval between the cyclopropenimine and the borane in the chemical structural formula A is C1-C30 (that is, in formula A, n is preferably 1-30).
[0018] For the preparation of the cyclopropenimine organoboron bifunctional catalyst of the present invention, the preparation method includes the following step (1) or steps (1) and (2):
[0019]
[0020] (1) Under an inert atmosphere, a cyclopropenium ion with a terminal olefin and a hydroboration reagent are mixed, an organic solvent is added, and the reaction is carried out at room temperature to 100 °C for 1 - 72 h. After the reaction is completed, the organic solvent is removed with n - hexane or n - pentane multiple times to obtain a catalyst precursor, which is a cyclopropenimine organoboron bifunctional catalyst with R1 being hydrogen in Formula A;
[0021] (2) A solvent and a base are added to deprotonate the catalyst precursor to obtain a crude product, and the crude product is extracted with an organic solvent to obtain the cyclopropenimine organoboron bifunctional catalyst with R1 not being hydrogen in Formula A.
[0022] The chemical structural formula of the cyclopropenium ion with a terminal olefin is
[0023] In the above structural formula, the definitions of R1, R2, R3, R4 and n are as described above: the substituents R1, R2, R3, R4 are the same or different and are selected from hydrogen, alkyl (preferably C1 - C50 alkyl, more preferably C3 - C15 alkyl) or aryl, wherein the substituents R1 and R2 form a ring covalently or do not form a ring, R3 and R4 form a ring covalently or do not form a ring, and R1 and R2 can form a ring covalently and / or R3 and R4 can form a ring covalently; X - is a counter ion; n is an integer from 1 to 50.
[0024] The X - is a counter ion, and X - is one or a combination of two or more of fluoride ion, chloride ion, bromide ion, iodide ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion.
[0025] Among them, the group formed by R1, R2, R3, R4 connected to nitrogen has the following structure:
[0026]
[0027] n and m are integers from 1 to 50.
[0028] The hydroboration reagent is selected from the following chemical structures:
[0029]
[0030] The organic solvent is one or a mixture of two or more of tetrahydrofuran, benzene, toluene, chloroform, dichloromethane, hexane, ether, carbon tetrachloride, N,N - dimethylformamide, ethyl acetate, 1,4 - dioxane in any proportion.
[0031] The base is a common organic base, for example, triethylamine, N,N - diisopropylethylamine, 1,8 - diazabicycloundec - 7 - ene; the solvent used for deprotonation is at least one of dichloromethane, tetrahydrofuran, chloroform.
[0032] The present invention also applies the cyclopropenimine organoboron bifunctional catalyst to the synthesis of organic small molecules or polymers, such as ring-opening copolymerization of cyclic monomers.
[0033] The ring-opening copolymerization monomers include, but are not limited to, the following structures:
[0034]
[0035] The chain transfer agent or initiator used in the synthesis reaction can be arbitrarily selected from one or more small molecules or macromolecular polymers containing active hydrogens such as amino groups, mercapto groups, hydroxyl groups, phenolic hydroxyl groups, carboxyl groups, etc., including but not limited to the following structures:
[0036]
[0037] Among them, the structural The alcoholic hydroxyl group, phenolic hydroxyl group, amino group or carboxylic acid group shown on the main chain of the macromolecular chain transfer agent does not represent the actual number of functional groups, and the actual number is any integer greater than or equal to 1.
[0038] The cyclopropenimine organoboron bifunctional catalyst of the present invention can also be supported on inorganic or organic substances for the preparation of organic small molecules or polymer materials.
[0039] Advantages of the present invention:
[0040] Compared with the prior art, the present invention integrates cyclopropenimine and borane through covalent connection into one molecule, showing excellent catalytic activity in the ring-opening polymerization of cyclic monomers. Due to the special stability conferred by B-N coordination, it has stronger air stability than traditional organoboron catalysts, and can precisely control the end groups of the resulting polymers and efficiently synthesize topological structure polymers, greatly enhancing the practicality of this type of catalyst. This method is expected to promote the development of high-performance organic catalysts and has broad application prospects, and can even be extended to other polymerization reactions. Description of the Drawings
[0041] Figure 1 It is the nuclear magnetic resonance hydrogen spectrum of catalyst A3 prepared in Example 3 of the present invention.
[0042] Figure 2 It is the nuclear magnetic resonance boron spectrum of catalyst A3 prepared in Example 3 of the present invention.
[0043] Figure 3 It is the nuclear magnetic resonance boron spectrum of catalyst A1 prepared in Example 1 of the present invention.
[0044] Figure 4 It is the nuclear magnetic resonance boron spectrum of catalyst A2 prepared in Example 2 of the present invention.
[0045] Figure 5 This is the X-ray single crystal diffraction pattern of catalyst A3 prepared in Example 3 of the present invention. Detailed implementation manners
[0046] The following examples are used to illustrate the present invention, but are not intended to limit the protection scope of the present invention. Unless otherwise specified, the technical means used in the examples are conventional means well known to those skilled in the art. The test methods in the following examples are all conventional methods unless otherwise specified.
[0047] The general preparation process of the precursors required for the examples is as follows:
[0048] (1) First, the general synthesis process of TAC is as follows: Add pentachlorocyclopropane (35 mmol) to a flask and dissolve it in 250 mL of chloroform. At 0 °C, slowly add secondary amine (280 mmol) and react for 2 h - 48 h. After the reaction, wash with 1 M hydrochloric acid, then extract with deionized water. The organic phase is concentrated in vacuo and separated by column chromatography to obtain white solid TAC.
[0049] (2) Add TAC (1.0 mmol, 1.0 equiv) to the reaction flask, then add terminal olefin amine (1.0 mmol, 1.0 equiv) and triethylamine (2.0 mmol, 2.0 equiv), dissolve in dichloromethane, stir for 48 h, and purify by column chromatography to obtain precursor 2.
[0050] The general structural formula of TAC involved is The prepared precursor 2 is
[0051]
[0052] The substituents R2, R3, R4, and R5 are the same or different and are selected from hydrogen, alkyl, or aryl, where the substituent R1 and R2 form a covalent ring or not, and R3 and R4 form a covalent ring or not; n is an integer from 1 to 50;
[0053] (3) General synthesis method of precursor of type A catalyst: In a glove box, sequentially add precursor 2 (0.5 mmol, 1.0 equiv) and 9-borabicyclo[3,3,1]nonane (9-BBN) (0.65 mmol, 1.3 equiv) to a 25 mL reaction tube, add 1.0 mL of anhydrous chloroform, and then react at 60 °C for 12 h. After monitoring the reaction to completion by 1 1H NMR, the reaction mixture is concentrated in vacuo to obtain a crude product, then washed three times with n-hexane for further purification to obtain a white solid. Finally, the white solid is dried in vacuo at 40 °C for 8 h to obtain a white powder of precursor of type A catalyst (quantitative yield).
[0054] The precursor structure of catalyst of type A is
[0055] Preparation of catalyst A1 in Example 1
[0056] The reaction path is as follows:
[0057]
[0058] In the glove box, 3a (1 mmol, 1.0 equiv) and sodium hydroxide (1 mmol, 1.0 equiv) were successively added to the reaction tube, 3.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 4 h. After 1 monitoring the completion of the reaction by 1H NMR, the crude product was concentrated under vacuum, then extracted with dichloromethane, the organic phase was dried and concentrated under vacuum to obtain a white solid, and finally the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A1 (quantitative yield).
[0059] 1H NMR characterization of A1 is as follows: 1 1H NMR (500 MHz, CDCl3) δ 3.45 - 3.38 (m, 2H), 3.30 - 3.20 (m, 4H), 1.92 - 1.71 (m, 20H), 1.70 - 1.56 (m, 10H), 1.54–1.44 (m, 10H), 1.32–1.20 (m, 10H), 1.16 - 1.11 (m, 4H), 0.63 (t, J = 3.4 Hz, 2H), 0.44 - 0.38 (m, 2H).
[0060] Preparation of catalyst A2 in Example 2
[0061] The reaction path is as follows:
[0062]
[0063] In the glove box, 3b (1 mmol, 1.0 equiv) and sodium tert-butoxide (4 mmol, 4.0 equiv) were successively added to the reaction tube, 3.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 1 h. After 1 monitoring the completion of the reaction by 1H NMR, the crude product was concentrated under vacuum, then extracted with dichloromethane, the organic phase was dried and concentrated under vacuum to obtain a white solid, and finally the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A2 (quantitative yield).
[0064] 1H NMR characterization of A2 is as follows: 11H NMR (500 MHz, CDCl3) δ 3.50 - 3.10 (m, 6H), 1.99 - 1.70 (m, 24H), 1.60 - 1.57 (m, 6H), 1.58 - 1.40 (m, 14H), 1.34 - 1.20 (m, 10H), 1.18 - 1.02 (m, 4H), 0.99 - 0.80 (m, 2H).
[0065] Example 3 Preparation of Catalyst A3
[0066] The reaction pathway is as follows:
[0067]
[0068] In the glove box, 3c (1 mmol, 1.0 equiv) and sodium hydride (2 mmol, 2.0 equiv) were successively added to the reaction tube, 3.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 3 h. After 1 monitoring the reaction to completion by 1H NMR, the crude product was concentrated under vacuum, then extracted with dichloromethane, the organic phase was dried and concentrated under vacuum to obtain a white solid, and finally the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A3 (quantitative yield).
[0069] 1H NMR characterization of A3 is as follows: 1 1H NMR (500 MHz, CDCl3) δ 3.51 - 3.46 (m, 3H), 3.36 - 3.30 (m, 1H), 3.24 - 3.16 (m, 2H), 1.92 - 1.70 (m, 20H), 1.66 - 1.52 (m, 20H), 1.43 - 1.24 (m, 15H), 1.17 - 1.04 (m, 5H), 0.64 - 0.53. (m, 2H).
[0070] 11B NMR characterization of A3 is as follows: 11 11B NMR (128 MHz, CDCl3) δ -6.6.
[0071] Example 4 Preparation of Catalyst A4
[0072] The reaction pathway is as follows:
[0073]
[0074] In the glove box, 3c (1 mmol, 1.0 equiv) and sodium hydroxide (3 mmol, 3.0 equiv) were successively added to the reaction tube, 3.0 mL of water and 3.0 mL of dichloromethane were added. Then the reaction was carried out at room temperature for 3 h. After 1After monitoring the completion of the reaction by \(^1\)H NMR, the crude product was concentrated under vacuum, followed by extraction with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A4 (quantitative yield).
[0075] Example 5 Preparation of Catalyst A5
[0076] The reaction pathway is as follows:
[0077]
[0078] In the glove box, 3e (2 mmol, 1.0 equiv) and sodium hydride (8 mmol, 4.0 equiv) were successively added to the reaction tube, 6.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 4 h. After monitoring the completion of the reaction by \(^1\)H NMR, the reaction mixture was concentrated under vacuum to obtain the crude product, followed by extraction with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A5 (quantitative yield). 1 After monitoring the completion of the reaction by \(^1\)H NMR, the reaction mixture was concentrated under vacuum to obtain the crude product, followed by extraction with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A5 (quantitative yield).
[0079] Example 6 Preparation of Catalyst A6
[0080] The reaction pathway is as follows:
[0081]
[0082] In the glove box, 3f (1 mmol, 1.0 equiv) and sodium tert-butoxide (4 mmol, 4.0 equiv) were successively added to the reaction tube, 3.0 mL of acetonitrile was added, and then the reaction was carried out at room temperature for 4 h. After monitoring the completion of the reaction by \(^1\)H NMR, the reaction mixture was concentrated under vacuum to obtain the crude product, followed by extraction with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder B2 (quantitative yield).
[0083] Example 7 Preparation of Catalyst A7
[0084]
[0085] In the glove box, 3g (1 mmol, 1.0 equiv) and sodium hydride (4 mmol, 4.0 equiv) were successively added to the reaction tube, 3.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 4 h. After monitoring the completion of the reaction by \(^1\)H NMR, the reaction mixture was concentrated under vacuum to obtain the crude product, followed by extraction with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A7 (quantitative yield).
[0086] Preparation of Catalyst A8 in Example 8
[0087] The reaction pathway is as follows:
[0088]
[0089] In a glove box, 3h (1 mmol, 1.0 equiv) and sodium hydride (4 mmol, 4.0 equiv) were successively added to a reaction tube, 3.0 mL of tetrahydrofuran was added, and then the reaction was carried out at room temperature for 4 h. After the reaction was monitored by 1H NMR to be complete, the reaction mixture was concentrated under vacuum to obtain a crude product, which was then extracted with dichloromethane. The organic phase was dried and concentrated under vacuum to obtain a white solid. Finally, the white solid was dried under vacuum at 40 °C for 8 h to obtain white powder A8 (quantitative yield).
[0090] A series of organic boron bifunctional catalysts based on cyclopropenimine were obtained in the above examples. To verify their catalytic activity, they were applied in the ring-opening copolymerization of epoxy and anhydride to evaluate the catalyst activity. The structures and abbreviations of the initiators and monomers involved in the following application examples are shown as follows:
[0091]
[0092] Application Examples 1 - 10: The ring-opening copolymerization of epoxy and anhydride was achieved by using the main catalyst A3 and different initiators together.
[0093]
[0094] The operation process is as follows:
[0095] In a glove box, the catalyst A3, initiator, anhydride, and epoxy were successively added to a reaction tube, sealed completely, placed in a preheated oil bath, and the polymerization was completed at 45 - 110 °C. The reaction solution was taken to measure NMR to characterize the conversion rate of the monomer and the selectivity of the product, and the polymerization molecular weight and molecular weight distribution were verified by GPC. The test results are shown in Table 1.
[0096] Table 1. Polymerization Results of Application Examples 1 - 10
[0097]
[0098] Among them, the ratio of CHO:PA:A3:initiator is 400:200:1; the conversion rate (%) in a represents the conversion rate of anhydride, and the selectivity (%) represents the content of ester bonds in the formed polymer, both of which are calculated by 1H NMR. M in B nand PDI were measured by GPC; in c, the catalyst was placed in air for 30 days and then polymerization was carried out, and the catalytic activity was not affected; in d, A3 was used for polymerization in air. These results fully demonstrate the catalytic activity and air stability of cyclopropenimine, greatly improving its practical application.
[0099] Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention. The present invention may also have various other embodiments. Without departing from the spirit and essence of the present invention, those skilled in the art can make various corresponding changes and deformations according to the present invention, but these corresponding changes and deformations should all fall within the protection scope of the appended claims of the present invention.
Claims
1. A cyclopropenimine organoboron bifunctional catalyst, characterized in that, The chemical structural formula of the catalyst is as follows: In formula A: the substituents R1, R2, R3, and R4 are the same or different and are selected from hydrogen, alkyl, or aryl, wherein the substituents R1 and R2 may or may not form a covalent ring, and R3 and R4 may or may not form a covalent ring; is borane; wherein, n is an integer from 1 to 50.
2. The cyclopropenimine organoboron bifunctional catalyst according to claim 1, characterized in that, The substituents R1, R2, R3, and R4 are the same or different and are selected from hydrogen, C1-C50 alkyl groups, or aryl groups; the borane is one of non-cyclic boranes and cyclic boranes.
3. The cyclopropenimine organic boron bifunctional catalyst according to claim 1 or 2, characterized in that The groups formed by connecting the substituents R1, R2, R3, and R4 to nitrogen are the same or different and are selected from the following structures: Among them, n and m are integers from 1 to 50.
4. The cyclopropenimine organoboron bifunctional catalyst according to claim 1 or 2, characterized in that, The borane moiety is selected from the following structures:
5. The cyclopropenimine organoboron bifunctional catalyst according to any one of claims 1 or 2, characterized in that, The distance between the cyclopropenimine and the borane in Chemical Structural Formula A is C1-C30.
6. The preparation method of the cyclopropenimine organic boron bifunctional catalyst according to any one of claims 1-5, characterized in that, The preparation method includes the following step (1) or steps (1) and (2): (1) Under an inert atmosphere, mix a cyclopropenium ion with a terminal olefin and a hydroborating reagent, add an organic solvent, and react at room temperature to 100 °C for 1-72 h. After the reaction, remove the organic solvent with n-hexane or n-pentane multiple times to obtain a catalyst precursor, which is a cyclopropenimine organoboron bifunctional catalyst with R1 being hydrogen in Formula A; (2) Add a solvent and a base to deprotonate the catalyst precursor to obtain a crude product, and extract the crude product with an organic solvent to obtain the cyclopropenimine organoboron bifunctional catalyst in Formula A where R1 is not hydrogen.
7. The preparation method according to claim 6, wherein The chemical structural formula of the cyclopropenium ion with a terminal olefin is The substituents R1, R2, R3, and R4 are the same or different and are independently selected from hydrogen, alkyl, or aryl, wherein R1 and R2 may or may not covalently form a ring, and R3 and R4 may or may not covalently form a ring; X - is a counterion; n is an integer from 1 to 50.
8. The preparation method according to claim 7, wherein The said X - is an anti-ion, specifically one or a combination of two or more of fluoride ion, chloride ion, bromide ion, iodide ion, tetrafluoroborate ion, hexafluorophosphate ion, carboxylate ion.
9. The preparation method according to claim 6, characterized in that, The organic solvent is one or more of tetrahydrofuran, benzene, toluene, chloroform, dichloromethane, hexane, ether, carbon tetrachloride, N,N-dimethylformamide, ethyl acetate, 1,4-dioxane, mixed in any proportion; The hydroborating reagent is selected from compounds with the following chemical structures:
10. Use of the cyclopropenimine organoboron bifunctional catalyst according to any one of claims 1-4 in the preparation of organic small molecules or polymers.