羟基功能化有机材料的构筑及其催化性能研究

Construction and Catalytic Performance of Hydroxyl Functionalized Organic Materials

随着温室气体剧增对地球生命系统构成威胁,对于二氧化碳(CO_(2))的减排、替代、捕捉与转化受到各国的重视.目前,CO_(2)作为反应物应用在与环氧化合物环加成生成环碳酸酯是CO_(2)转化领域中最有前景的途径,生成的环碳酸酯可作为高沸点的极性溶剂、锂电池电解液等投入应用.有机多孔聚合物(POP)具有合成方式多样、高比表面积、低密度、高孔隙率、结构可调等优异性能,且引入合适的官能团可以更好地提高固定CO_(2)的能力,所以将其作为催化CO_(2)与环氧化物环加成反应的非均相催化剂有着不错的前景.以3,3'-二羟基联苯胺(DB)和四(4-甲酰基苯基)乙烯(TPE)为单体通过溶剂热法制备了DB-TPE-POP,通过红外光谱、^(13)C固体核磁共振波谱、氮气吸脱附曲线和扫描电子显微镜等表征,证实了DB-TPE-POP的成功制备,并将其应用在CO_(2)与1,2-环氧丁烷的环加成反应,转化率为85%,产物选择性达到99%.之后进行底物拓展,发现空间位阻对环加成反应有重要的影响,空间位阻越大,反应转化率越低;以卤素元素作为取代基的底物转化率均达到86%以上,说明DB-TPE-POP对这类底物催化效果优异.总体上看,不同的环氧化合物均有不错的转化率,并且产物选择性均在99%以上,证实DB-TPE-POP对CO_(2)环加成反应具有优良的普适性.最后探讨其催化机理,表明羟基是CO_(2)环加成反应中重要的活性位点.

As the amounts of greenhouse gases soar,they pose a threat to earth’s living systems.As a result,many countries have emphasized reducing,replacing,capturing,and converting carbon dioxide(CO_(2))emissions.Currently,the most promising approach for CO_(2)conversion involves the use of CO_(2)as a reactant in cycloaddition reactions with epoxides to generate cyclic carbonates.These cyclic carbonates can serve as polar solvents with high boiling points and as lithium battery electrolytes among other applications.Porous organic polymer(POP)exhibits excellent properties,such as diverse synthetic methods,high specific surface area,low density,high porosity,and adjustable structure.By introducing appropriate functional groups into POPs,their ability to capture CO_(2)can be signifycantly enhanced.Consequently,POPs hold great potential as heterogeneous catalysts for cycloaddition reactions between CO_(2)and epoxides.Using 3,3′-dihydroxybenzidine(DB)and tetra(4-formylphenyl)ethylene(TPE)as monomers,DB-TPE-POP was prepared via the solvothermal method.The successful preparation of DB-TPE-POP was confirmed by infrared spectroscopy,^(13)C solid-state nuclear magnetic resonance spectroscopy,nitrogen adsorptiondesorption curves,and scanning electron microscopy.DB-TPE-POP was applied in the cycloaddition reaction of CO_(2)and 1,2-epoxybutane and was found to exhibit a conversion rate of 85%and product selectivity of 99%.Subsequently,substrate expansion was carried out,and it was determined that steric hindrance has an important impact on the cycloaddition reaction;the larger the steric hindrance,the lower the reaction conversion rate.The conversion rates of substrates with halogen substituents were all above 86%,indicating that DB-TPE-POP has excellent catalytic effects on such substrates.Overall,different epoxides had good conversion rates and product selectivities above 99%,confirming the excellent universality of DB-TPE-POP for CO_(2)cycloaddition reactions.Finally,the catalytic mechanism was explored,and the results indicated that hydroxyl groups are important active sites for CO_(2)cycloaddition reactions.