Acid-functionalized Mesoporous Silicate (KIT-5-Pr-SO3H) Synthesized as an Efficient and Nanocatalyst for Green Multicomponent

Abstract

Aim and Objective: KIT-5 nanoporous silica was functionalized with sulfonic acid and SO3H group has been immobilized on nanoporous KIT-5 silica support via in situ method to produce novel nanocatalyst as "KIT-5-Pr-SO3H". The catalyst was fully characterized by FT-IR, SEM, EDXs, TEM, BET and TGA techniques. The surface morphology images approved that the nanocatalyst particle sizes are around 7-15 nm. The prepared catalyst was efficiently used in the synthesis of benzimidazolo quinazolinones, imidazo1,2-achromeno4,3-dpyrimidinone and imidazo1,2-apyrimidine via a multicomponent reaction under green conditions. The easy synthesis condition, environmental compatibility, high specific surface area, reusability for 5 run without loses in any activity, high selectivity, availability of raw material, are the remarkable properties for this new catalyst. Materials and Methods: All reagents were purchased from Aldrich and Merck with high-grade quality and used as received. The structural characteristics of the KIT-5 which was obtained, using three-dimensional large cage type face-centered cubic Fm3m mesoporous silica materials (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Results: The purpose of this study is developing a new acid-functionalized mesoporous catalyst. Initially, (KIT-5) nanocages were obtained according to the procedure described by Kleitz et al. Then, KIT-5-Pr-SH was prepared by Mercaptopropyltriethoxysilane as illustrated in Scheme 1. In the next step, the solid product was oxidized with H2O2. The full characterization for proving the structure of the nano-size particles was achieved using FT-IR, TGA, TEM, SEM, and EDX analysis. Conclusion: Acid-functionalized mesoporous silica has been proved to act as an effective catalyst in various organic reactions. In this project, for the first time, KIT-5 was functionalized by propyl-sulfonic acid as a heterogeneous solid acid catalyst. Sulfonic acid functionalized KIT-5 (KIT-5-Pr-SO3H) performs as an organic-inorganic hybrid catalyst, whereas Bronsted acid sites have been selectively generated. In this regard, the catalytic activities of this novel heterogeneous catalyst were successfully examined by the one-pot multicomponent reaction.