Star-shaped Keggin-type heteropolytungstate nanostructure as a new catalyst for the preparation of quinoxaline derivatives
作者:Majid Masteri-Farahani、Melika Ghorbani、Ali Ezabadi、Niki Farrokhinia、Atekeh-Sadat Ghaemmaghami
DOI:10.1016/j.crci.2014.01.021
日期:2014.11
Résumé In this work, we report the novel successful preparation of the Keggin-type Cs(CTA)2PW12O40 (CTA = cetyltrimethylammonium cation) nanostructure by a microemulsion method. The microemulsion system included the cationic surfactant CTAB, 1-butanol as co-surfactant, isooctane as oil phase, and an aqueous solution containing CsNO3. The Cs(CTA)2PW12O40 nanostructure was formed by the addition of an aqueous solution of phosphotungstic acid to the microemulsion solution. Characterization of the resultant nanostructure was done using FT–IR spectroscopy, X-ray diffraction, scanning electron microscopy, energy-dispersive X-ray analysis, and CHN elemental analysis. The product was found to be a star-shaped nanostructure composed of some nanorods whose diameter and length are about 100 nm and 500 nm, respectively. The prepared nanostructure was used as a recoverable catalyst for the synthesis of quinoxaline derivatives by the condensation of 1,2-diamines with 1,2-dicarbonyl compounds, which afforded the products in good to high yields in short reaction times.
摘要
在本研究中,我们报道了通过微乳液法成功制备Keggin型Cs(CTA)2PW12O40(CTA = 十六烷基三甲基氨离子)纳米结构的新方法。微乳液系统包括阳离子表面活性剂CTAB、作为助表面活性剂的1-丁醇、油相的异庚烷,以及含有CsNO3的水溶液。通过向微乳液溶液中加入磷酸钨的水溶液,形成了Cs(CTA)2PW12O40纳米结构。结果纳米结构的表征采用了FT-IR光谱、X射线衍射、扫描电子显微镜、能量色散X射线分析和CHN元素分析。研究发现,所得到的产物为星形纳米结构,由一些直径约为100 nm、长度约为500 nm的纳米棒组成。所制备的纳米结构被用作可回收催化剂,以1,2-二胺与1,2-二酮化合物的缩合合成氟喹啉衍生物,反应在短时间内能获得良好至高产率的产物。