Preparation method and application of chiral spiro-diborane organic catalyst
Through the preparation and application of chiral spirocyclic biborane organic catalyst, the three-dimensional regularity and catalyst dosage problems of ring-opening polymerization of epoxy compounds in the prior art are solved, and high-efficiency and low-temperature polyether preparation is achieved, and polyether is expanded. scope of application.
Patent Information
- Application Number
- CN202411311021.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2024-09-20
- Publication Date
- 2024-12-27
AI Technical Summary
The prior art is difficult to achieve asymmetric ring-opening polymerization of epoxy compounds under mild conditions at low catalyst dosage, and it is difficult to prepare polyethers of high stereoregularity, and metal-based catalysts have problems with insufficient functional group tolerance and metal residue.
The chiral spirocyclic biborane organic catalyst is prepared by performing borohydrogenation reaction with the borohydrogenation reagent in a specific solvent, and the polymerization reaction is carried out under low temperature conditions with initiator to achieve efficient ring-opening polymerization of epoxy compounds.
High-efficiency catalysis below room temperature and high stereoregularity polyethers are obtained at low catalyst dosage, which broadens the application range of polyethers and improves the activity and yield of the catalyst.
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Figure CN119192210A_ABST
Abstract
Description
Technical Field
[0001] The invention belongs to the field of catalyst synthesis, and in particular relates to a synthesis method and application of a chiral spirocyclic biborane catalyst. Background Art
[0002] Polyethers are widely used in non-ionic surfactants, drug release, clinical medicine, thermal or pH stimulus responsive materials, etc. Polyethers with different main structural regularity exhibit different thermomechanical properties, and regular polyethers often show material properties that are superior to their random analogs. For example, isotactic poly PPO is semi-crystalline with a melting point of 67°C. These properties are very promising for application in new environmentally friendly products.
[0003] At present, the development of catalysts for the ring-opening polymerization (ROP) of epoxides with good stereocontrol is still a challenge. Most of them are metal-based polymerization systems, such as heterogeneous Pruitt-Baggett catalysts, Vandenberg catalysts or bimetallic Co(III)- or Cr(III)-based Coates-type systems. The latter type does provide perfect isotactic polyethers and can be considered as the benchmark for stereoselectivity. However, metal-based catalysts have limited functional group tolerance, harsh synthesis conditions and metal residues. In many cases, the prepared polyethers have a wide molecular weight distribution. Therefore, the development of non-metallic catalytic systems has become a hot topic. Borane-catalyzed ring-opening polymerization of epoxides to prepare polyethers has good functional group tolerance, catalytic activity, low catalyst loading and good controllability. At present, the research on borane-catalyzed epoxy compounds to achieve high stereoregularity polyethers stays in the synthesis of axial chiral organoboron catalysts, and there is no report on central chiral boron. Summary of the invention
[0004] In order to realize the asymmetric ring-opening polymerization preparation of epoxy compounds under mild conditions and low catalyst dosage conditions, and to realize the preparation of polyethers with high stereoregularity, the present invention provides a chiral spirocyclic biborane organic catalyst, a preparation method and its application. The chiral spirocyclic biborane organic catalyst provided by the present invention has high catalytic performance for propylene oxide and ethylene oxide, the polymerization reaction can be carried out below room temperature, a high monomer conversion rate can be achieved at extremely low catalyst dosage, and high stereoregularity can be achieved, thereby broadening the application range of polyethers.
[0005] As a first aspect of the present invention, the present invention provides a chiral spirocyclic biborane catalyst, wherein the organic catalyst has any of the following structures:
[0006]
[0007]
[0008] As a second aspect of the present invention, the present invention provides a method for preparing the chiral spirocyclic biborane organic catalyst.
[0009] The preparation method is as follows: a precursor is added into dichloromethane, and then reacted with a borohydride reagent (HBR2) to prepare the organic catalyst through a borohydride reaction.
[0010] Preferably, the hydroboration reagent is 9-borabicyclo (3,3,1)-nonane, referred to as 9-BBN; or dicyclohexylborane, referred to as HBCy2; or cyclohexylborane, referred to as HBCy; or cyclopentylborane, referred to as HBPent.
[0011] Specifically, the preparation method of the chiral spirocyclic biborane organic catalyst is as follows: tetrahydrofuran or dichloromethane (5-500 mL) is added to a central chiral precursor (1 mmol-1 mol) containing a double bond, and then a borohydride reagent (2 mmol-2 mol) is added dropwise, and the reaction is heated at 25-60° C. for 12 to 24 hours, and the reaction mixture is vacuum-dryed to obtain a crude product, and the crude product is recrystallized with pentane (2-20 mL) and then vacuum-dryed to obtain a central chiral boron catalyst.
[0012] Preferably, the organic solvent is one or a mixed solvent of at least two of tetrahydrofuran, benzene, toluene, chloroform, dichloromethane, hexane, ether, carbon tetrachloride, N,N-dimethylformamide, ethyl acetate, and 1,4-dioxane.
[0013] The initiator is a halogen ion or an alcohol initiator, and the alcohol initiator includes but is not limited to methanol, ethanol, 2-propanol, n-butanol, 2-methyl-2-propanol, benzyl alcohol, terephthalyol, 1,2-propylene glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, glycerol, pentaerythritol, allyl alcohol, propargyl alcohol, 2-(dibenzylamino)ethanol, furan-2-methanol, N-(2-hydroxyethyl)acrylamide, 4,5-dimethoxy-2-nitrobenzyl alcohol, N-(tert-butoxycarbonyl)ethanolamine, tert-butyl glycolate, 2-azidoethanol, hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and other functionalized alcohols.
[0014] Preferably, the molar ratio of the catalyst precursor to the hydroboration agent is 1:1-1:1.2.
[0015] As a third aspect of the present invention, the present invention also provides the use of the chiral spirocyclic biborane organic catalyst in the preparation of polyether polyols by ring-opening polymerization.
[0016] The specific method for preparing polyether polyols comprises: under the protection of degassing, pre-mixing the chiral spirocyclic biborane organic catalyst and initiator uniformly, contacting with propylene oxide at -40-45°C to generate polymerization reaction, and obtaining stereoregular polypropylene oxide.
[0017] Preferably, the anhydrous gas is nitrogen.
[0018] Preferably, the reaction temperature is -36°C, -20°C, 0°C, 25°C.
[0019] Preferably, the reaction time is 0.5-72 hours, preferably 0.5, 1, 2, 6, 12, 24, 36, 48 hours.
[0020] Preferably, the molar ratio of the initiator to the organic catalyst is (1-1000):1, and the molar ratio of the Lewis base to the organic catalyst is 1:1.
[0021] The present invention also provides the use of a chiral spirocyclic biborane organic catalyst in catalytic polymerization to prepare a polymer. The polymerization reaction is ring-opening polymerization, and the polymer obtained by polymerization is a polyether.
[0022] Furthermore, the present invention provides the use of a chiral spirocyclic biborane catalyst in catalyzing small organic molecules. Furthermore, the epoxy monomer includes but is not limited to the following structure:
[0023]
[0024]
[0025] Beneficial effects of the present invention
[0026] (1) The chiral spirocyclic biborane organic catalyst provided by the present invention has the advantages of high activity, simple preparation method, high yield, etc. This type of catalyst can regulate the type of polymerization substrate and polymer by regulating the reaction conditions, catalytic system, substrate, etc. Due to the characteristics of the central chirality, the types of chiral boron catalysts are greatly expanded.
[0027] (2) The chiral spirocyclic biborane catalyst provided by the present invention not only has a high conversion rate in catalyzing the ring-opening polymerization reaction, but also has a high stereoregularity of the obtained polymer. BRIEF DESCRIPTION OF THE DRAWINGS
[0028] Figure 1 Chiral spirocyclic biborane organocatalyst precursor 1 1 H NMR;
[0029] Figure 2 The single crystal structure of the chiral spirocyclic center biborane organocatalyst precursor 1
[0030] Figure 3 Chiral spirobiborane organocatalyst CAT1 1 HNMR; DETAILED DESCRIPTION
[0031] Example 1: Preparation of Precursor
[0032] In a glove box, add 1 g (s)-spirocyclodiphenol, 0.824 mL allyl bromide, and 3632 mg potassium carbonate to 8 mL acetonitrile solution, take out, pass nitrogen, set up a condenser, and react at room temperature for 72 hours. After the reaction, add dichloromethane to dissolve, filter, drain, and recrystallize with 1.5 mL pentane.
[0033] Example 2: Synthesis of Catalyst 1
[0034] 322.18 mg of the precursor and 250.2 mg of 9-BBN were dissolved in 5 mL of dichloromethane, reacted at 50° C. for 24 hours, drained, and recrystallized with 1.5 mL of pentane.
[0035] The following are examples of the application of central chiral skeleton organoboron catalysts in polymerization reactions.
[0036] Examples 1-13
[0037] Homopolymerization of alkylene oxide (PO) catalyzed by catalyst / organic base
[0038]
[0039] In a glove box, PO, chiral spirocyclic diborane and Lewis base are weighed into a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, the vial is sealed and taken out, and the reaction temperature is set at -20 to 45°C. The molar ratio of PO to chiral spirocyclic diborane and Lewis base is 200:1:1 to 10000:1:1, and the reaction time is controlled at 0.5 to 24 h.
[0040] Example 3
[0041] In a glove box, CAT1 (8.18 mg, 0.0142 mmol, 1 equivalent), Bu4NCl (9.9 mg, 0.0071 mmol, 0.5 equivalent) and PO (0.994 ml, 14.2 mmol, 1000 equivalent) were added to a 10 ml pressure vial that had been dried at high temperature in advance and equipped with a magnetic stirrer. The mixture was reacted at 25 °C for 1 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.15, m=79%, mm=66%.
[0042] Example 4
[0043] In a glove box, add CAT1 (40.9 mg, 0.071 mmol, 1 equivalent), Bu4NCl (10 mg, 0.036 mmol, 0.5 equivalent) and PO (24.8 mL, 355 mmol, 5000 equivalent) to a flame-dried 50 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 0.5 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.14, m=76%, mm=65%.
[0044] Example 5
[0045] In a glove box, CAT1 (2.07 mg, 0.0036 mmol, 1 equivalent), Bu4NCl (0.5 mg, 0.0018 mmol, 0.5 equivalent) and PO (2.48 mL, 35.5 mmol, 10000 equivalent) were added to a pre-flame dried 10 mL pressure vial equipped with a magnetic stirrer, and the mixture was reacted at 25 °C for 0.5 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.17, m=75%, mm=64%.
[0046] Example 6
[0047] In a glove box, add CAT1 (1.38 mg, 0.0024 mmol, 1 equivalent), Bu4NCl (0.3 mg, 0.0012 mmol, 0.5 equivalent) and PO (4.97 mL, 71 mmol, 30000 equivalent) to a pre-flame dried 10 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 0.5 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.14, m=70%, mm=61%.
[0048] Example 7
[0049] In a glove box, CAT1 (4.09 mg, 0.0071 mmol, 1 equivalent), Bu4NCl (9.9 mg, 0.036 mmol, 0.5 equivalent) and PO (4.97 mL, 71 mmol, 10000 equivalent) were added to a 10 mL pressure vial that had been flame-dried in advance and equipped with a magnetic stirrer. The mixture was reacted at 25 °C for 1 h. After the reaction was completed, the reaction was quenched and diluted with a small amount of dichloromethane. Part of the reaction solution was taken to detect the molecular weight distribution. It is 1.16, m=80%, mm=67%.
[0050] Example 8
[0051] In a glove box, add CAT3 (409.2 mg, 0.71 mmol, 1 equivalent), tetrabutylammonium succinate (216 mg, 0.36 mmol, 0.5 equivalent) and PO (49.7 mL, 710 mmol, 1000 equivalent) to a 250 mL pressure bottle that has been flame-dried in advance and equipped with a magnetic stirrer. React at 25 °C for 1 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.17, m=83%, mm=69%.
[0052] Example 9
[0053] In a glove box, add CAT1 (40.9 mg, 0.071 mmol, 1 equivalent), tetrabutylammonium succinate (21.6 mg, 0.036 mmol, 0.5 equivalent) and PO (24.8 mL, 355 mmol, 5000 equivalent) to a 50 mL pressure vial that has been flame-dried and equipped with a magnetic stirrer. The mixture is reacted at 25 °C for 1 h. After the reaction is completed, the reaction is quenched, diluted with a small amount of dichloromethane, and part of the reaction solution is taken for detection. Molecular weight distribution It is 1.14, m=78%, mm=63%.
[0054] Example 10
[0055] In a glove box, add CAT1 (12.2 mg, 0.0213 mmol, 1 equivalent), tetrabutylammonium succinate (6.4 mg, 0.0107 mmol, 0.5 equivalent) and PO (14.9 mL, 213 mmol, 10000 equivalent) to a pre-flame dried 50 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 1 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.15, m=76%, mm=63%.
[0056] Embodiment 11
[0057] In a glove box, add CAT1 (4.09 mg, 0.0071 mmol, 1 equivalent), tetrabutylammonium succinate (9.9 mg, 0.036 mmol, 1 equivalent) and PO (4.97 mL, 71 mmol, 10000 equivalent) to a pre-flame dried 10 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 2 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.17, m=81%, mm=67%.
[0058] Example 12
[0059] In a glove box, add CAT1 (40.9 mg, 0.071 mmol, 1 equivalent), Bu4NCl (10 mg, 0.036 mmol, 0.5 equivalent) and PO (24.8 mL, 355 mmol, 5000 equivalent) to a flame-dried 50 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 2 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.15, m=83%, mm=69%.
[0060] Example 13
[0061] In a glove box, CAT1 (40.9 mg, 0.071 mmol, 1 equivalent), Bu4NCl (10 mg, 0.036 mmol, 0.5 equivalent) and PO (49.7 mL, 710 mmol, 10000 equivalent) were added to a 50 mL pressure vial that had been dried at high temperature in advance and equipped with a magnetic stirrer. The reaction was allowed to proceed at 25 °C for 3 h. After the reaction was completed, the reaction was quenched, a small amount of dichloromethane was added for dilution, and part of the reaction solution was taken for detection. , Molecular weight distribution It is 1.16, m=73%, mm=62%.
[0062]
[0063] Examples 14-22
[0064] Homopolymerization of alkylene oxide (PO) catalyzed by CAT1 / organic base / initiator
[0065] In a glove box, PO, chiral spirocyclic diborane, organic base, and initiator are weighed into a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, the vial is sealed and taken out, and the reaction temperature is set at -20 to 45° C. The molar ratio of PO to chiral spirocyclic diborane, organic base, and initiator is 200:1:1:10 to 10000:1:1:1000, and the reaction time is controlled at 0.5 to 24 h.
[0066] The specific operations of Examples 14 to 23 are as follows, and the key data are summarized in Table 2.
[0067] Embodiment 14
[0068] In a glove box, CAT1 (40.9 mg, 0.071 mmol, 1 equivalent), DBU (0.106 mL, 0.71 mmol, 10 equivalents), ethylene glycol (0.396 mL, 7.1 mmol, 100 equivalents) and PO (24.8 mL, 355 mmol, 5000 equivalents) were added to a 50 mL pressure vial that had been flame-dried and equipped with a magnetic stirrer. The reaction was allowed to proceed at 25 °C for 0.5 h. After the reaction was completed, the reaction was quenched, a small amount of dichloromethane was added to dilute the mixture, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.14, m=79%, mm=67%.
[0069] Embodiment 15
[0070] In a glove box, add CAT1 (2.07 mg, 0.0036 mmol, 1 equivalent), DBU (0.0054 mL, 0.036 mmol, 10 equivalents), BDM (49 mg, 0.36 mmol, 100 equivalents) and PO (2.48 mL, 35.5 mmol, 10000 equivalents) to a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 0.5 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.17, m=75%, mm=63%.
[0071] Example 16
[0072] In a glove box, CAT1 (1.38 mg, 0.0024 mmol, 1 equivalent), DBU (0.0036 mL, 0.024 mmol, 10 equivalents), benzyl alcohol (0.0249 mL, 0.24 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 30000 equivalents) were added to a pre-flame dried 10 mL pressure vial equipped with a magnetic stirrer, and the mixture was reacted at 25 °C for 0.5 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.14, m=71%, mm=61%.
[0073] Embodiment 17
[0074] In a glove box, CAT1 (4.09 mg, 0.0071 mmol, 1 equivalent), P1 (9.9 mg, 0.036 mmol, 10 equivalents), ethylene glycol (0.396 mL, 7.1 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 10000 equivalents) were added to a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, and the mixture was reacted at 25 °C for 0.5 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.17, m=74%, mm=61%.
[0075] Embodiment 18
[0076] In a glove box, add CAT1 (4.09 mg, 0.0071 mmol, 1 equivalent), P2 (92.6 mg, 0.071 mmol, 10 equivalents), benzyl alcohol (0.0738 ml, 0.71 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 10000 equivalents) to a 250 mL pressure bottle that has been flame-dried in advance and equipped with a magnetic stirrer. The reaction was carried out at 25 °C for 2 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.17, m=77%, mm=64%.
[0077] Embodiment 19
[0078] In a glove box, add CAT1 (2.07 mg, 0.0036 mmol, 1 equivalent), P4 (71.1 mg, 0.036 mmol, 10 equivalents), BDM (33.15 mg, 0.36 mmol, 100 equivalents) and PO (2.48 mL, 35.5 mmol, 10000 equivalents) to a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 1 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.17, m=78%, mm=65%.
[0079] Embodiment 20
[0080] In a glove box, CAT1 (1.38 mg, 0.0024 mmol, 1 equivalent), P1 (5.6 mg, 0.024 mmol, 10 equivalents), benzyl alcohol (0.0249 mL, 0.24 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 30000 equivalents) were added to a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, and the mixture was reacted at 25 °C for 0.5 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.14, m=73%, mm=61%.
[0081] Embodiment 21
[0082] In a glove box, add CAT1 (4.09 mg, 0.0071 mmol, 1 equivalent), P2 (92.6 mg, 0.071 mmol, 10 equivalents), BDM (98.09 mg, 0.71 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 10000 equivalents) to a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, and react at 25 °C for 0.5 h. After the reaction is completed, quench the reaction, add a small amount of dichloromethane to dilute, and take part of the reaction solution for detection. Molecular weight distribution It is 1.17, m=72%, mm=60%.
[0083] Embodiment 22
[0084] In a glove box, add CAT1 (4.0 mg, 0.0071 mmol, 1 equivalent), P1 (16.6 mg, 0.071 mmol, 10 equivalents), BDM (98.09 mg, 0.71 mmol, 100 equivalents) and PO (4.97 mL, 71 mmol, 10000 equivalents) to a 250 mL pressure bottle that has been flame-dried in advance and equipped with a magnetic stirrer. The reaction was carried out at 25 °C for 2 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution It is 1.17, m=81%, mm=66%.
[0085]
[0086]
[0087] Embodiment 23-24
[0088] Homopolymerization of chiral alkylene oxides catalyzed by catalysts / organic bases
[0089] In a glove box, chiral PO, chiral spirocyclic diborane and Lewis base are weighed into a pre-flame-dried 10 mL pressure vial equipped with a magnetic stirrer, the vial is sealed and taken out, and the reaction temperature is set at -20-45°C. The molar ratio of PO to chiral spirocyclic diborane and Lewis base is 200:1:1-10000:1:1, and the reaction time is controlled at 0.5-24h.
[0090] Embodiment 23
[0091] In a glove box, CAT1 (8.18 mg, 0.0142 mmol, 1 equivalent), Bu4NCl (9.9 mg, 0.0071 mmol, 0.5 equivalent) and (S)-PO (0.994 mL, 14.2 mmol, 1000 equivalent) were added to a 10 ml pressure vial that had been dried at high temperature in advance and equipped with a magnetic stirrer. The reaction was allowed to proceed at 25 °C for 1 h. After the reaction was completed, the reaction was quenched, diluted with a small amount of dichloromethane, and part of the reaction solution was taken for detection. Molecular weight distribution 1.15, m = 81%, mm = 67%
[0092] Embodiment 24
[0093] In a glove box, CAT1 (8.18 mg, 0.0142 mmol, 1 equivalent), Bu4NCl (9.9 mg, 0.0071 mmol, 0.5 equivalent) and (R)-PO (0.994 mL, 14.2 mmol, 1000 equivalent) were added to a 10 ml pressure vial that had been dried at high temperature in advance and equipped with a magnetic stirrer. The reaction was allowed to proceed at 25 °C for 1 h. After the reaction was completed, the reaction was quenched, a small amount of dichloromethane was added for dilution, and part of the reaction solution was taken for detection. Molecular weight distribution 1.15, m = 79%, mm = 66%
[0094]
[0095] The above data show that the chiral spirocyclic biborane organic catalyst has a high polymerization conversion rate for epoxy compounds and a certain improvement in stereopolymerization degree compared with some previous organic catalysts.
[0096] The above description is only a preferred embodiment of the present invention, and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the above embodiments, those skilled in the art can still modify the technical solutions described in the above embodiments, or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, modification, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.
Claims
1. A binuclear boron catalyst based on central chirality, characterized in that: Its general structure is as follows: BR2 Groups and below or R is any one of methyl, ethyl, alkyl, phenyl, and substituted phenyl. m is any positive integer of 1-3.
2. A binuclear boron catalyst based on central chirality, characterized in that: Its structure is preferably as follows:
3. The binuclear boron catalyst based on S-center chirality according to claim 2, wherein the synthetic precursor is preferably any one of the following structures:
4. The method for preparing the catalyst according to any one of claims 1, characterized in that: The following steps are involved: Add tetrahydrofuran or dichloromethane (5-500 mL) to a central chiral precursor (1 mmol-1 mol) containing a double bond, then dropwise add a borohydride reagent (2 mmol-2 mol), heat the reaction at 25-60° C. for 12-24 h, vacuum-dry the reaction mixture to obtain a crude product, recrystallize the crude product with pentane (2-20 mL) and vacuum-dry it to obtain a central chiral boron catalyst; The molar ratio of the central chiral precursor of the double bond to the borohydride reagent is 1:2.05-1: 2.10, the borohydride reagent includes any one of 9-borabicyclo(3,3,1)-nonane, dicyclohexylborane, cyclohexylborane or cyclopentylborane.
5. Use of the catalyst according to any one of claims 1 in combination with a Lewis base or an organic base to construct a Lewis acid-base pair in catalytic polymerization to prepare a polymer, characterized in that: The polymerization reaction is a ring-opening polymerization of epoxy monomers, and the prepared polymer is a polyether.
6. The structure of the Lewis base or organic base according to any one of claims 3 to 4 is any one of the following structures: The halogen ions used include but are not limited to tetrabutylammonium chloride, tetrabutylammonium bromide, tetrabutylammonium succinate, BrPPh4, BrPPh3nBu, BrPPh3Me Preferred initiator organic bases include but are not limited to the following structures: NEt3, N,N,N',N'-tetraethylethylenediamine, 7. The catalytic polymerization reaction of claim 4 may be added with additional protic species to regulate the molecular weight, sequence structure and terminal functional groups of the polymer, and the added protic species include but are not limited to any one of the following chemical formulas: ROH, R is H, alkyl, substituted alkyl, aryl, substituted aryl, substituted groups containing unsaturated bonds such as azide, olefin, alkyne, nitro, ester, amide, amine, carboxylic acid, etc. Alcohol initiators include but are not limited to methanol, ethanol, 2-propanol, n-butanol, 2-methyl-2-propanol, benzyl alcohol, terephthalyol, 1,2-propylene glycol, ethylene glycol, propylene glycol, butylene glycol, hexylene glycol, 2-butyl-2-ethyl-1,3-propanediol, neopentyl glycol, glycerol, pentaerythritol, allyl alcohol, propargyl alcohol, 2-(dibenzylamino)ethanol, furan-2-methanol, N-(2-hydroxyethyl)acrylamide, 4,5-dimethoxy-2-nitrobenzyl alcohol, N-(tert-butoxycarbonyl)ethanolamine, tert-butyl glycolate, 2-azidoethanol, hydroxyethyl acrylate, 2-hydroxyethyl methacrylate and other functionalized alcohols. The invention belongs to the field of catalyst synthesis, and in particular relates to a synthesis method of a chiral boron catalyst and application thereof.