Nanocrystalline FeOClx grafted MCM-41 as active mesoporous catalyst for the solvent-free multi-condensation reaction

Thermal condensation reaction between the surface silanol groups of MCM-41 and FeCl3 led to the formation of nanocrystalline iron oxychloride (FeOCl) grafted MCM-41 and its role as an active Lewis acid site for the solvent-free multi-condensation reaction has been demonstrated. TGA/TGA-FTIR-GC-MS analysis of the FeCl3/MCM-41 material showed the release of HCl molecules as a result of the condensation reaction and the formation of FeOClx species on the surface of MCM-41. Solid state Si29 NMR and HT-XRD analysis of these materials clearly showed the grafting of FeOClx species on the surface of MCM-41 and nanocrystalline FeOClx formation during the thermal condensation reaction. HRTEM mapping and EDX mapping further confirm the nanocrystalline iron oxychloride species formation and its uniform distribution on the surface of MCM-41. It was further demonstrated that these materials were found to be highly active towards solvent-free one pot multi condensation reaction between napthols, amides and aldehydes to produce pharmaceutically active alkylnapthols. The role of calcination temperature was demonstrated to be a key factor in the formation and distribution of FeOClx species, therefore the catalytic activity of these materials vary as a function of calcination temperature. XPS analysis of these materials confirmed the presence of FeOClx species and its role as an active acid site for the multi-condensation reaction was proposed.