Formation of Iron/MCM-41 Nanocomposites with Trifunctional Ligand via Dodecyl Trimethylammonium Bromide (DTAB) Surfactant: Two Heterogeneous Catalysts for the Green Synthesis of 5-Substituted 1H-Tetrazoles

Abstract

Two organic–inorganic mesoporous hybrid materials containing iron complexes covalently attached to mesoporous silica MCM-41 have been successfully prepared via post-functionalization modification of MCM-41 (with trifunctional ligand and without the ligand). The catalysts were characterized by Fourier transforms infrared spectra, powder X-ray diffraction, scanning electron microscopy, and N₂ adsorption/desorption. For the composite MCM-41/3,4,5-tri hydroxyphenyl acetic acid/Fe and MCM-41/Fe materials, in the presence of DTAB (dodecyl trimethylammonium bromide), results showed the formation of more stable MCM-41 structure with the higher surface area than in the presence of CTAB (cetyltrimethylammonium bromide) surfactants. The catalysts were tested in the synthesis of 5-substituted 1H-tetrazoles. This catalyst is an efficient catalyst for [3 + 2] cycloaddition with NaN₃ to prepare 5-substituted 1H-tetrazoles. The catalyst was recycled for up to seven cycles without significant loss of activity.