催化学报 ›› 2015, Vol. 36 ›› Issue (11): 1825-1836.DOI: 10.1016/S1872-2067(15)60964-0

• 论文 • 上一篇    下一篇

多壁碳纳米管负载Cu2O和CuI催化剂上芳醛与2-氨基吡啶氧化酰胺化反应:Cu(I)物种的催化作用

H. N. Hareesha, K. U. Minchithaa, N. Nagarajub, N. Kathyayinia   

  1. a 耆那大学纳米生物科学系新兴技术中心, 格讷格布尔, 卡纳塔克邦, 印度;
    b 圣约学院及研究中心化学系催化研究实验室, 班加罗尔, 卡纳塔克邦, 印度
  • 收稿日期:2015-06-23 修回日期:2015-08-12 出版日期:2015-11-02 发布日期:2015-11-02
  • 通讯作者: N. Kathyayini. 电话: +91-98-86506387; 传真: +91-80-27577211; 电子信箱: nkathyayini45@gmail.com

Catalytic role of Cu(I) species in Cu2O/CuI supported on MWCNTs in the oxidative amidation of aryl aldehydes with 2-aminopyridines

H. N. Hareesha, K. U. Minchithaa, N. Nagarajub, N. Kathyayinia   

  1. a Department of Nanobiosciences, Centre for Emerging Technologies, Jain Global Campus, Jain University, Jakkasandra Post, Kanakapura Taluk, Ramanagara District-562112, Karnataka, India;
    b Catalysis Research Laboratory, Department of Chemistry, St. Joseph's College and Research Centre, 46 Langford Road, Shanthinagar Bengaluru-560027, Karnataka, India
  • Received:2015-06-23 Revised:2015-08-12 Online:2015-11-02 Published:2015-11-02

摘要:

采用浸渍法制备了多壁碳纳米管(MWCNT)负载的Cu2O和CuI催化剂, 并运用粉末X射线衍射、红外光谱、扫描电镜-能量散射谱、透射电镜和NH3程序升温脱附等技术对催化剂进行了表征. 结果表明, 催化剂中沉积的Cu2O和CuI分别以立方相和γ相存在于MWCNT上, 且表现出由弱到强的拉电子(Lewis酸)性能. 将催化剂用于催化芳醛与2-氨基吡啶氧化酰胺化反应合成N-(吡啶-2-基)苯酰胺类化合物, 产物选择性为100%, 收率为50%-95%. CuI/MWCNT催化剂上产物分离收率性能好于Cu2O/MWCNT, 但后者的循环使用性能更好. 与共价的CuI相比, 离子化的Cu2O与极性的酸活化的MWCNT间具有更适宜的相互作用, 这种不同的相互作用可显著影响2-氨基吡啶的氨基对芳醛羰基的亲核进攻速率.

关键词: 氧化亚铜, 碘化铜, 多壁碳纳米管, 2-氨基吡啶, 氧化酰胺化

Abstract:

Cu2O and CuI were supported on multiwalled carbon nanotubes (MWCNTs) using a wet impregnation method, and the resulting materials were fully characterized by powder X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy, transmission electron microscopy, and temperature-programmed desorption with ammonia analysis. The results of these experiments revealed that Cu2O and CuI were deposited on the MWCNTs in the cubic and γ phases, respectively. These results also showed that the Cu-containing MWCNTs exhibited weak to strong electron-accepting (Lewis acidic) properties. The catalytic activities of these materials were studied for the synthesis of biologically significant N-(pyridin-2-yl)benzamides via the oxidative amidation of aryl aldehydes with 2-aminopyridines. The yields of the products were in the range 50%-95% with 100% selectivity. Notably, the CuI/MWCNT catalyst was much more effective than the Cu2O/MWCNT catalyst with respect to the isolated yield of the product, although the latter of these two catalysts exhibited much better recyclability. A preferential interaction was observed between the polar nature of the acid-activated MWCNTs and the ionic Cu2O compared with covalent CuI. The differences in these interactions had a significant impact on the rate of the nucleophilic attack of the amino group of 2-aminopyridine substrate on the carbonyl group of the aryl aldehyde.

Key words: Cuprous oxide, Cuprous iodide, Multiwalled carbon nanotube, 2-Aminopyridine, Oxidative amidation