Preparation, characterization and catalytic activity of dendrimer-encapsulated phosphotungstic acid nanoparticles immobilized on nanosilica for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones under solvent-free or sonochemical conditions
作者:Mohsen Esmaeilpour、Jaber Javidi、Farzaneh Dehghani
DOI:10.1007/s13738-015-0782-x
日期:2016.4
In this paper, we adopt a facile method to prepare a type of porous silica nanoparticles (n-SiO2) from tetraethyl orthosilicate as the source of silica. Then, dendritic polymer supported on nanosilica with surface amino groups was fabricated. Finally, H3PW12O40 nanoparticles (PWAn) were synthesized by the treatment of H3PW12O40 powder with n-Octane as solvent by a solvothermal method and then immobilized onto the dendrimer polymer functionalized nanosilica. The synthesized nanostructures were characterized by fourier transform infrared (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), dynamic light scattering (DLS), N2 adsorption–desorption isotherm analysis, UV–Vis and elemental analysis. The morphology of the catalyst was characterized using transmission electron microscopes (TEM). The acidity of the catalyst was determined by FTIR pyridine adsorption spectroscopy. Then, this catalytic system was used as an efficient catalyst for the synthesis of 2H-indazolo[2,1-b]phthalazine-triones via multi-component and one-pot reactions of various aldehydes, phthalic anhydride, hydrazinium hydroxide, and dimedone under thermal solvent-free conditions or ultrasound irradiation at room temperature. Also, the catalyst can be easily recovered and reused for six consecutive reaction cycles without significant loss of activity.
本文采用一种简便的方法,以正硅酸四乙酯为硅源制备了一种多孔纳米二氧化硅(n-SiO2)。然后,在纳米二氧化硅上制备了带有表面氨基的树枝状聚合物。最后,以正辛烷为溶剂,通过溶热法处理 H3PW12O40 粉末,合成了 H3PW12O40 纳米粒子(PWAn),并将其固定在树枝状聚合物功能化的纳米二氧化硅上。傅立叶变换红外(FT-IR)、X 射线衍射(XRD)、热重分析(TGA)、动态光散射(DLS)、N2 吸附-解吸等温线分析、紫外-可见光和元素分析对合成的纳米结构进行了表征。使用透射电子显微镜(TEM)对催化剂的形态进行了表征。催化剂的酸度是通过傅立叶变换红外吡啶吸附光谱测定的。然后,该催化体系被用作一种高效催化剂,用于在室温下无溶剂热条件或超声辐照条件下,通过各种醛、邻苯二甲酸酐、氢氧化肼和二甲基酮的多组分和一锅反应合成 2H-吲唑并[2,1-b]酞嗪三酮类化合物。此外,该催化剂可轻松回收并重复使用,连续反应六个循环而不会明显丧失活性。