Catalytic role of Cu(I) species in Cu_2O/CuI supported on MWCNTs in the oxidative amidation of aryl aldehydes with 2-aminopyridines  

多壁碳纳米管负载Cu_2O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（英文）

作　　者：H. N. Hareesh K. U. Minchitha N. Nagaraju N. Kathyayini 

机构地区：[1]耆那大学纳米生物科学系新兴技术中心,印度卡纳塔克邦格讷格布尔 [2]圣约学院及研究中心化学系催化研究实验室,印度卡纳塔克邦班加罗尔

出　　处：《Chinese Journal of Catalysis》2015年第11期1825-1836,共12页催化学报（英文）

基　　金：DST-SERB for the financial support for this research work(Project number:SERB/F/3690/2013-14)

摘　　要：Cu2O and Cul were supported on multiwalled carbon nanotubes （MWCNTs） using a wet impregna- tion 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 CuL 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.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%.Cu I/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Cu I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：Cuprous oxide Cuprous iodide Multiwalled carbon nanotube2-Aminopyridine Oxidative amidation 

分 类 号：O621.251[理学—有机化学] O643.36[理学—化学]