Cost effective one-pot photocatalytic synthesis of quinaldines from nitroarenes by silver loaded TiO2

In order to get materials with enhanced adsorption and photocatalytic performance, nanosized silver particles loaded TiO2 was prepared by a facile photodeposition. This catalyst was characterized by X-ray diffraction (XRD), high resolution transmission electron microscopy (HR-TEM). X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller surface area (BET) and diffuse reflectance spectroscopy (DRS). XRD patterns revealed that the crystal structure of Ag-TiO2 resembled anatase phase of TiO2. Visible light absorption increases with the increase in Ag loading. Photoluminescence spectra indicate the suppression of recombination of the photogenerated electron-hole pairs by the loaded silver on TiO2. XPS measurements reveal the presence of silver particles mainly in metallic form. 1.5% Ag loaded TiO2 is found to be most efficient for selective one-pot synthesis of quinaldines from nitroarenes in ethanol using UV light. Ag-TiO2 on irradiation induces a combined redox reaction with nitroarene and alcohol and this is followed by condensation-cyclization of aniline and oxidation products to give quinaldines. (C) 2011 Elsevier B.V. All rights reserved.