Journal of Molecular Catalysis A-Chemical, Vol.420, 246-253, 2016
Silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride catalyzed synthesis of spiropyran derivatives
In this research, a novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4diaza-bicyclo[2.2.2joctane-sulfonic acid chloride (SBDBSAC), as an acidic ionic liquid based on 1,4-diaza-bicyclo[2.2.2]octane ring bonded to silica has been prepared and fully characterized by several techniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential thermogravimetric (DTG), scanning electron microscope (SEM), transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The nanostructured catalyst has been suxessfully used as reusable nanostructured catalyst for green, simple and efficient synthesis of spiropyrans by the one-pot tandem Knoevenagel-Michael-cyclization reaction of isatin derivatives or acenaphthenquinone with barbituric acid derivatives, and 1,3-dicarbonyl compounds under aqueous media. (c) 2016 Elsevier B.V. All rights reserved.
Keywords:Spiropyran;Silica-bonded;1,4-diaza-bicyclof2.2.2]octane-sulfonic acid;chloride;Nanostructured catalyst;lsatin;Barbituric acid;Aqueous media