發(fā)布時間：2018-05-20 16:30

  本文選題：多孔有機聚合物 + 多相催化��； 參考：《催化學(xué)報》2017年04期

【摘要】：不對稱氫甲�；呛铣删哂袉我还鈱W(xué)活性物質(zhì)(如光學(xué)活性的醛、α-氨基酸和醇等)最為重要的反應(yīng)之一.盡管不對稱氫甲�；磻�(yīng)的研究超過40年,但仍然是催化體系中具有挑戰(zhàn)性的課題.該反應(yīng)涉及到產(chǎn)物的化學(xué)選擇性、立體選擇性和對映體選擇性的優(yōu)化.目前,在Rh催化體系中,使用磷-亞磷酸酯手性配體或雙亞磷酸酯配體可以在不對稱氫甲�；磻�(yīng)中取得優(yōu)異的催化性能.然而在Rh/手性雙膦配體催化體系中,不對稱氫甲�；磻�(yīng)性能通常很低.以BINAP配體為例,負載Rh金屬后,在催化苯乙烯不對稱氫甲�；磻�(yīng)中,產(chǎn)物的ee值只有25%.同時,由于均相催化體系存在催化劑回收和產(chǎn)物提純等問題,因此有必要研究多相不對稱氫甲�；磻�(yīng)催化劑.本文使用乙烯基修飾的BINAP配體5,5'-divinyl-BINAP與具有不同結(jié)構(gòu)的共聚單體二乙烯基苯或1,3,5-三乙烯基苯基苯共聚,得到具有不同孔結(jié)構(gòu)的聚合物Poly-1和Poly-2.為了比較,利用線性共聚單體乙二醇二甲基丙烯酸甲酯與乙烯基BINAP共聚得到聚合物Poly-3.上述三種聚合物材料負載金屬Rh后,用作苯乙烯不對稱氫甲�；磻�(yīng)的催化劑.固體~(13)C核磁分析表明,三種聚合物材料負載金屬后仍然保持較為穩(wěn)定的C骨架結(jié)構(gòu).通過~(31)P核磁可以看到,嵌入在材料骨架中的BIANP仍然保持未被氧化的狀態(tài).N_2物理吸附結(jié)果發(fā)現(xiàn)Poly-1和Poly-2具有較大的比表面積和孔體積,而Poly-3的比表面積最小.熱重分析顯示,這些材料具有較高的熱穩(wěn)定性.在不同反應(yīng)溶劑中催化劑活性差異較大.通過優(yōu)化反應(yīng)溫度和合成氣壓力后,催化劑Rh/Poly-1在80℃和0.2MPa下產(chǎn)物的對映體選擇性可高達58.9%,支鏈醛與直鏈醛的比值為8.5;而在相同反應(yīng)條件下,均相催化劑Rh-BINAP的ee值僅為35.3%,但高于Rh/Poly-3.這是由于三個多相催化劑骨架中BINAP周圍環(huán)境不同所致.前兩個催化劑中,BINAP與空間位阻較大的單體相連接,使得反應(yīng)底物按照特定方向與催化活性位點接觸,形成了類似于手性口袋的結(jié)構(gòu).而Rh/Poly-3中,BIANP周圍是線性的共聚單體,不能形成有效的手性口袋結(jié)構(gòu).Rh/Poly-1重復(fù)使用7次后,催化活性沒有顯著下降.拓展X射線吸收精細結(jié)構(gòu)表征結(jié)果表明,Rh/Poly-1催化劑使用前沒有Rh-Rh鍵存在,但經(jīng)重復(fù)使用后,Rh金屬部分聚集,生成了Rh-Rh鍵.球差電鏡照片也證實了這一點.
[Abstract]:Asymmetric hydroformylation is one of the most important reactions for the synthesis of single optically active substances such as aldehydes, 偽 -amino acids and alcohols. Although asymmetric hydroformylation has been studied for more than 40 years, it is still a challenging subject in catalytic systems. The reaction involves the optimization of the chemical selectivity, stereoselectivity and enantioselectivity of the product. At present, in the Rh catalytic system, the chiral ligand or bisphosphite ligands can obtain excellent catalytic performance in asymmetric hydroformylation. However, asymmetric hydroformylation in Rh/ chiral diphosphine ligands is generally low. Taking the BINAP ligand as an example, the ee value of the product was only 25 in the asymmetric hydroformylation of styrene catalyzed by Rh metal. At the same time, it is necessary to study the heterogeneous asymmetric hydroformylation catalyst because of the problems of catalyst recovery and product purification in homogeneous catalytic system. In this paper, the vinyl modified BINAP ligands 5- divinyl-BINAP and divinyl-BINAP with different structures were copolymerized with divinylbenzene or 1 / 3 trivinylbenzene. Poly-2 and Poly-1 with different pore structures were obtained by the copolymerization of divinylbenzene and divinyl-BINAP with different pore structures. Poly-3 was synthesized by copolymerization of methyl glycol dimethacrylate and vinyl BINAP. The above three polymer materials supported metal Rh were used as catalysts for asymmetric hydroformylation of styrene. The results of NMR analysis show that the C skeleton structure of the three polymer materials is still stable after metal loading. It can be seen by NMR that the BIANP embedded in the material skeleton remains unoxidized. The physical adsorption results of Poly-1 and Poly-2 show that Poly-1 and Poly-2 have larger specific surface area and pore volume, while Poly-3 has the smallest specific surface area. Thermogravimetric analysis shows that these materials have high thermal stability. The activity of catalyst varies greatly in different reaction solvents. After optimizing reaction temperature and syngas pressure, the enantioselectivity of catalyst Rh/Poly-1 at 80 鈩，

本文編號：1915408