Preparation and Modification of Magnetic Mesoporous Silica-Alumina Composites as Green Catalysts for the Synthesis of Some Indeno[1,2-b]Indole-9,10-Dione Derivatives in Water Media

Abstract

In this work, magnetic mesoporous silica-alumina composites (MSA) containing three metal oxides(MSA/MO) with different molar ratio of Si to Al (0.5, 1 and 2) were synthesized. The efficiency of prepared catalysts was compared with modified natural zeolite (ferrierite) in the multicomponent synthesis of indeno[1,2-b]indole-9,10-diones. Immobilization of ZnO, CuO and NiO on magnetic composites increased their Lewis acidic sites and improved their catalytic activity. Also magnetic property of designed catalysts enhanced their capability and easy separation. Among the mentioned composites, the catalyst with the molar ratio of S/A = 2 show the best efficiency in the synthesis of indeno[1,2-b]indole-9,10-diones under thermal conditions and water as green solvent. FT-IR, XRD, FE-SEM, EDX, elemental mapping, BET and VSM techniques were used to characterize the prepared composites. The synthesized products were obtained in high to excellent yields and their structures were confirmed by 1HNMR, 13CNMR and FT-IR spectroscopy.