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Abstract
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tIn this research, a novel nanostructured heterogeneous catalyst, namely silica-bonded 1,4-diaza-bicyclo[2.2.2]octane-sulfonic acid chloride (SBDBSAC), as an acidic ionic liquid based on1,4-diaza-bicyclo[2.2.2]octane ring bonded to silica has been prepared and fully characterized by severaltechniques such as fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD), thermo-gravimetric analysis (TGA), differential thermogravimetric (DTG), scanning electron microscope (SEM),transmission electron microscopy (TEM) and energy dispersive X-ray analysis (EDX). The nanostruc-tured catalyst has been suxessfully used as reusable nanostructured catalyst for green, simple andefficient synthesis of spiropyrans by the one-pot tandem Knoevenagel-Michael-cyclization reaction ofisatin derivatives or acenaphthenquinone with barbituric acid derivatives, and 1,3-dicarbonyl compoundsunder aqueous media.
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