A polyboron organic metal-free catalyst, a preparation method and application thereof

Abstract

The application discloses a polyboron organic non-metallic catalyst and a preparation method and application thereof. The polyboron organic non-metallic catalyst is prepared by a one-step method through a boron-hydrogen reaction of a polymer containing a double bond and a compound containing a boron-hydrogen bond, has simple operation, and has 100% atomic economy. Compared with the existing small-molecule organic borane, the catalyst has the characteristics of wide monomer application range, high selectivity, wide temperature use interval, and simple preparation process, can be applied to catalyzing an epoxy monomer homopolymerization reaction and an epoxy monomer copolymerization reaction, and has extremely high catalytic activity due to the increased concentration of activated epoxy monomers around a growing chain.

Description

Technical Field

[0001] This invention relates to the field of catalyst synthesis technology, and more specifically, to a multi-boron organic metal-free catalyst, its preparation method, and its application. Background Technology

[0002] The preparation of polymer materials using non-metallic catalysts is currently a research hotspot. In recent years, non-metallic bicomponent catalytic systems composed of small-molecule organoboranes and organic bases have flourished in the field of epoxide ring-opening (co)polymerization, providing a green and safe new method for preparing polymer materials such as polyethers, carbon dioxide-based polycarbonates, polyesters, polythiocarbonates, and polyurethanes. However, the activity of small-molecule organoborane / organic base bicomponent catalytic systems is not high, especially at low catalyst concentrations where they lose activity. Furthermore, small-molecule organoboranes are sensitive to water and oxygen, and deactivation can generate large amounts of flammable gases, posing production safety hazards. They are also prone to decomposition at high temperatures, limiting their operating temperature. Therefore, there is a need to develop novel and highly efficient non-metallic catalysts. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a multi-boron organic metal-free catalyst and its preparation method.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A multi-boron organic metal-free catalyst has the structure shown in formula (1), where m≥0, n≥2, and are integers;

[0006]

[0007] R1-R5 are selected from the following groups, either unsubstituted or substituent: C1-C 10 Alkyl, C3-C 12 cycloalkyl, C3-C 12 alkenyl or ynyl, C3-C 12 Heterocyclic group, C6-C 20 One or more of the heteroaryl groups, or the group containing one or more atoms; R6 is a group containing an unsaturated double bond.

[0008] Preferably, among the commercially available multiboron organic metal-free catalysts, the multiboron organic metal-free catalyst is selected from one of the following structures:

[0009]

[0010] Where n≥2.

[0011] The preparation method of the above-mentioned multi-boron organic metal-free catalyst includes the following steps: mixing a polymer containing one or more unsaturated bonds with a compound containing boron-hydrogen bonds under inert gas protection, using tetrahydrofuran as solvent, reacting at room temperature to 80°C for 5-48 hours, and removing the solvent after the reaction to obtain the multi-boron organic metal-free catalyst.

[0012] Preferably, in the above preparation method, the polymer containing one or more unsaturated bonds is selected from one or more of the following:

[0013]

[0014] Where k≥2.

[0015] Preferably, in the above preparation method, the compound containing boron-hydrogen bonds is selected from one or more of the following:

[0016]

[0017] Preferably, in the above preparation method, the molar ratio of the number of double bonds in the polymer containing one or more unsaturated bonds to the number of boron-hydrogen bonds in the compound containing boron-hydrogen bonds is 0.5-10.

[0018] The above-mentioned multi-boron organic-metal-free catalyst is used in the ring-opening homopolymerization of epoxides, copolymerization with other monomers, or reactions derived from the above polymerization. The multi-boron organic-metal-free catalyst is used in combination with an organic base, and the molar ratio of the multi-boron organic-metal-free catalyst to the organic base is 0.5-5:1. The organic base is one or more of bis(triphenylphosphine)ammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

[0019] Compared with existing technologies, this invention has the following advantages: This invention uses a polymer containing double bonds and a compound containing boron-hydrogen bonds to prepare a novel multi-boron organic metal-free catalyst in one step via a hydroboration reaction. The operation is simple and possesses 100% atom economy. Compared with currently available small-molecule organoboranes, this catalyst has a wide range of applicable monomers, high selectivity, a wide operating temperature range, and a simple preparation process. It can be applied to catalyze homopolymerization and copolymerization of epoxides. Due to the increased concentration of activated epoxides around the growing chains, it exhibits extremely high catalytic activity. Attached Figure Description

[0020] Figure 1 This is a comparison of the NMR spectra of catalyst I obtained in Example 1 of the present invention and the raw material;

[0021] Figure 2The NMR spectrum of the copolymer prepared by catalyst I in Example 1 of this invention is shown.

[0022] The present invention can be further explained and illustrated in conjunction with the following specific embodiments, but the specific embodiments do not limit the present invention in any way. Detailed Implementation

[0023] Example 1

[0024] In a nitrogen-atmospheric glove box, 0.5000 g of polybutadiene, 1.1775 g of 9-boron-bicyclo[3.3.1]nonane, and 10 mL of tetrahydrofuran were sequentially added to a Shrek tube with a stir bar. The tube was sealed and transferred to a 65°C oil bath for heating and stirring for 24 h. The solvent was removed by rotary evaporation to obtain 1.6775 g of white solid, which was multi-boron organic non-metallic catalyst I, as shown in formula (2), with a yield of 100%. In an anhydrous and oxygen-free environment, 16 g of phthalic anhydride, 50.2 g of propylene oxide, 31.0 mg of bis(triphenylphosphine)ammonium chloride, and 9.5 mg of catalyst I were sequentially added to a high-pressure reactor. Carbon dioxide was introduced at 1.0 MPa, and the reaction was carried out at 80°C for 10 h. After the reaction was completed, the carbon dioxide pressure was released, and samples were taken from the reactor for molecular weight testing and NMR analysis. The polymer product has a molecular weight of 100 kg / mol, PDI = 1.30, cyclic carbonate content of 2.3 wt%, and TOF value of 300 h⁻¹. -1 .

[0025]

[0026] Example 2

[0027] In a glove box under a nitrogen atmosphere, 1.2848 g of an alternating copolymer of allyl glycidyl ether and tetrahydrophthalic anhydride, 0.5887 g of 9-boronibira[3.3.1]nonane, and 20 mL of tetrahydrofuran were sequentially added to a Shrek tube with a stir bar. The tube was sealed and transferred to a 50°C oil bath for heating and stirring for 12 h. The Shrek tube was then transferred to a glove box, and 0.3954 g of borocyclohexane was added. The tube was sealed and transferred to a 50°C oil bath for further heating and stirring for 15 h. The solvent was removed by rotary evaporation, yielding 2.2689 g of a white solid, which was multiboron organic nonmetallic catalyst II (see formula (3)), with a yield of 100%. In a glove box under a nitrogen atmosphere, 6.1 mg of catalyst II, 7.2 mg of tetrabutylammonium chloride, and 15 g of propylene oxide were added to a glass bottle containing a stir bar. The mixture was stirred at room temperature for 10 h, with a TOF value of 500 h. -1 .

[0028]

[0029] Example 3

[0030] In a nitrogen-atmospheric atmosphere glove box, 2.5307 g of an alternating copolymer of allyl glycidyl ether and phthalic anhydride, 2.5698 g of (+)-diisopinepineborane, and 30 mL of tetrahydrofuran were sequentially added to a Shrek tube with a stir bar. The tube was sealed and transferred to a 70°C oil bath for heating and stirring for 36 h. The solvent was removed by rotary evaporation to obtain 5.1005 g of white solid, which was multiboron organic non-metallic catalyst III (see formula (4), with a yield of 100%). In an anhydrous and oxygen-free environment, 50.2 g of propylene oxide, 1.5579 g of butanediol, 49.6 mg of bis(triphenylphosphine)ammonium chloride, and 91.4 mg of catalyst III were sequentially added to a high-pressure reactor. Carbon dioxide was introduced at 1.0 MPa, and the reaction was carried out at 80°C for 12 h. After the reaction was completed, the carbon dioxide pressure was released, and samples were taken from the reactor for molecular weight testing and NMR analysis. The polymer product has a molecular weight of 2.2 kg / mol, PDI = 1.03, cyclic carbonate content of 0.9 wt%, and TOF value of 483 h⁻¹. -1 .

[0031]

[0032] Example 4

[0033] In a nitrogen-atmospheric glove box, 1.0722 g of alternating copolymer of propylene oxide and norbornene, 0.8594 g of dicyclohexylborane, and 10 mL of tetrahydrofuran were sequentially added to a Shrek tube with a stir bar. The tube was sealed and transferred to a 65°C oil bath for heating and stirring for 36 h. The solvent was removed by rotary evaporation to obtain 1.9316 g of white solid, which was multiboron organic non-metallic catalyst IV (see formula (5)), with a yield of 100%. In an anhydrous and oxygen-free environment, 16 g of phthalic anhydride, 50.2 g of propylene oxide, 31.0 mg of bis(triphenylphosphine)ammonium chloride, and 21.6 mg of catalyst IV were sequentially added to a high-pressure reactor. Carbon dioxide was introduced at 1.0 MPa, and the reaction was carried out at 80°C for 10 h. After the reaction was completed, the carbon dioxide pressure was released, and samples were taken from the reactor for molecular weight testing and NMR analysis. The polymer product has a molecular weight of 87.3 kg / mol, PDI = 1.28, cyclic carbonate content of 3.1 wt%, and TOF value of 260 h⁻¹. -1 .

[0034]

[0035] Example 5

[0036] In a nitrogen-atmospheric glove box, 0.7533 g of alternating copolymer of propylene oxide and maleic anhydride, 1.3813 g of (+)-diisopinepineborane, and 10 mL of tetrahydrofuran were sequentially added to a Shrek tube with a stir bar. The tube was sealed and transferred to a 65°C oil bath for heating and stirring for 36 h. The solvent was removed by rotary evaporation to obtain 2.1346 g of white solid, which was multiboron organic non-metallic catalyst V, as shown in formula (6), with a yield of 100%. In an anhydrous and oxygen-free environment, 16 g of phthalic anhydride, 50.2 g of propylene oxide, 31.0 mg of bis(triphenylphosphine)ammonium chloride, and 23.9 mg of catalyst V were sequentially added to a high-pressure reactor. Carbon dioxide was introduced at 1.0 MPa, and the reaction was carried out at 80°C for 10 h. After the reaction was completed, the carbon dioxide pressure was released, and samples were taken from the reactor for molecular weight testing and NMR analysis. The polymer product has a molecular weight of 77.6 kg / mol, PDI = 1.28, cyclic carbonate content of 3.3 wt%, and TOF value of 220 h⁻¹. -1 .

[0037]

[0038] Comparative Example 1

[0039] In an anhydrous and oxygen-free environment, 16.0 g of phthalic anhydride, 50.2 g of propylene oxide, 31.0 mg of bis(triphenylphosphine)ammonium chloride, and 54 μL of triethylboron solution were sequentially added to a high-pressure reactor. The reactor was then purged with 1.0 MPa of carbon dioxide and reacted at 80 °C for 10 h. After the reaction was complete, the carbon dioxide pressure was released. Upon opening the reactor, the system viscosity was found to be low. Samples were taken for molecular weight determination and NMR analysis. The product molecular weight was only 20.3 kg / mol, no carbon dioxide product was detected, and the TOF value was only 60 h⁻¹. -1 .

[0040] Comparative Example 2

[0041] In an anhydrous and oxygen-free environment, 7.2 mg of tetrabutylammonium chloride, 15 g of propylene oxide, and 26 μL of triethylboron solution were added sequentially to a glass flask containing a stir bar. The mixture was stirred at room temperature for 10 h, with a TOF value of 50 h. -1 .

[0042] Comparative Example 3

[0043] In an anhydrous and oxygen-free environment, 50.2 g of propylene oxide, 1.5579 g of butanediol, 49.6 mg of bis(triphenylphosphine)ammonium chloride, and 174 μL of triethylboron solution were sequentially added to a high-pressure reactor. The reactor was then purged with 1.0 MPa of carbon dioxide and reacted at 80 °C for 12 h. After the reaction was complete, the carbon dioxide pressure was released, and samples were taken for molecular weight determination and NMR analysis. The product was a cyclic carbonate; no polycarbonate was formed, and the TOF value was only 42 h. -1 .

[0044] Based on the results of Examples 1-5 and Comparative Examples 1-3, it can be seen that multi-boron organic non-metallic catalysts have significantly improved activity compared to small-molecule organoboranes, especially in carbon dioxide polymerization, where they maintain high activity and high selectivity even at low catalyst dosages. Small-molecule organoboranes, on the other hand, lose their activity for carbon dioxide polymerization.

Claims

1. A multi-boron organic metal-free catalyst, characterized in that... Its structure is shown below, where m≥0, n≥2, and are integers; 。 2. A method for preparing the multi-boron organic metal-free catalyst according to claim 1, characterized in that... It is obtained by reacting the following two monomers. 。 3. The preparation method according to claim 2, characterized in that... The molar ratio of the number of double bonds in the first monomer to the number of boron-hydrogen bonds in the second monomer is 0.5-10.

4. The use of the multiboron organic metal-free catalyst of claim 1 in the ring-opening homopolymerization of epoxides, copolymerization with other monomers, or reactions derived from the above polymerization.

5. The application as described in claim 4, characterized in that... The multi-boron organic-metal-free catalyst is used in combination with an organic base, and the molar ratio of the multi-boron organic-metal-free catalyst to the organic base is 0.5-5:

1.

6. The application as described in claim 5, characterized in that... The organic base is one or more of bis(triphenylphosphino)ammonium chloride, tetrabutylammonium chloride, tetrabutylammonium bromide, triethylamine, and 1,8-diazabicyclo[5.4.0]undec-7-ene.

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