South African Journal of Chemistry
On-line version ISSN 1996-840X
RAFIEE, Ezzat; ZOLFAGHARIFAR, Zohreh; JOSHAGHANI, Mohammad and EAVANI, Sara. Dodecatungstocobaltate and Sn (IV)-substituted polyoxometalate: Preparation, characterization and catalytic performances in solventless synthesis of bis(indolyl)methanes. S.Afr.j.chem. (Online) [online]. 2012, vol.65, pp. 138-144. ISSN 1996-840X.
Electrophilic substitution reaction of indole with various aldehydes and cyclohexanone were carried out in the presence of electron-transfer (K5CoW12O40.3H2O) and green Lewis acid ([(n-C4H9)4N]3PMo2W9(Sn4+.H2O)O39) catalysts. These catalysts were characterized by N2-adsorption measurements, FT-IR, UV-Vis, 31P NMR, TGA, cyclic voltammetry and elemental analysis. Mechanisms for their catalytic activity are proposed. Both of these catalysts can be recovered and reused.
Keywords : Dodecatungstocobaltate; Sn (IV)-substituted polyoxometalate; bis(indolyl)methanes; electrophilic substitution; solvent-free conditions.