Catalytic properties of novel cyclodextrin dimers in the hydrolytic cleavage ofp-nitrophenyl alkanoates
作者:Mei-Ming Luo、Ru-Gang Xie、Ping-Fang Xia、Ling Tao、De-Qi Yuan、Hua-Ming Zhao
DOI:10.1002/poc.379
日期:2001.8
Novel cyclodextrin (CD) dimers (3a–c) linked by multidentate ligands were prepared by reacting 6-deoxy-6-(hydroxyethylamino)-β-CD (2) with p- and m-bis(bromomethyl)benzene and 2,6-bis(bromomethyl)pyridine, respectively. The catalytic properties of 2, 3b and 3c in the hydrolytic cleavage of p-nitrophenyl alkanoates, namely acetate (PNPA), butanoate (PNPB), hexanoate (PNPH) and octanoate (PNPO), were
新颖的环糊精(CD)二聚体(3A-C通过齿配体连接)由6-脱氧-6-(羟基乙基氨基)反应,制备-β-CD(2)与p -和米双(溴甲基)苯和2,6- -双(溴甲基)吡啶。的催化性质2,图3b和图3c中的水解裂解p硝基苯基链烷酸酯,即乙酸酯(PNPA),丁酸乙酯(PNPB),己酸盐(PNPH)和辛酸(PNPO),进行了研究。CD二聚体3b和3c在中性附近显示出适度的速率增强。尽管在3b存在下催化速率常数(k c)或3c随酯链长度的变化不显着,“长链”酯(PNPH和PNPO)的米氏常数K M远小于“短链”酯(PHPA和PNPB)的米氏常数,因此,“长链”酯的选择性因子(k c / K M)比“短链”酯的选择性因子大得多,这表明CD二聚体在水解过程中具有良好的尺寸识别能力和底物选择性。对硝基苯基链烷酸酯。向反应介质中添加Cu 2+对K M的影响不大,但导致K M的显着增加。ķ Ç在,因此增加ķ Ç