Magnetic Cellulose Nanofibers Supported Imidazolium-Based Ionic Liquid as a Biodegradable Catalyst for the Synthesis of Quinoline Derivatives

Abstract

Ionic liquids are a class of liquids that are composed solely of ions. They are non-volatile, non-flammable, thermally stable, and have excellent solvation properties, thus find potential applications in catalysis, electrochemistry. Supported ionic liquid catalysis is a concept which combines the advantages of ionic liquids with those of heterogeneous support materials [1]. As an excellent support, cellulose is of great interest due to its good biocompatibility, biodegradation and non-toxicity. Furthermore, the cellulose nanofibers (CNF) has a large surface area, many available functional groups and high mechanical strength, which makes it an attractive candidate as a supporting material for the synthesis of heterogeneous catalysis. On other hand, as the recovery of the most heterogeneous catalysts from the final reaction systems requires filtration or centrifugation step as a time consuming and tedious process, for this reason, they have been coated with magnetic nanoparticles. Magnetically recoverable catalysts can be easily separated with an external magnetic field [2]. Because of quinoline importance as substructures in a wide range of natural and semisynthetic products, significant efforts are directed to the development and construction of new quinoline-based structures [3]. In this study we report the synthesis of imidazolium-based ionic liquid immobilizated on magnetic cellulose nanofibers (Fe3O4@NFC-IIL-HSO4) and its identification by various techniques like FTIR, TGA, SEM, TEM, ICP-AES and VSM. The applicability of the constructed heterogeneous nanocatalyst was explored in the synthesis of quinoline derivatives through reaction of 2-Aminobenzophenones with ketones and diketones at 90 °C under solvent-free conditions in excellent yields. NH2 Ph O O O O N Ph O N Ph Cat. Cat. 90 oC, solvent-free 90 oC, solvent-free References [1] Z.Q. Zheng, J. Wang, T.H. Wu, X.P. Zhou, Advanced Synthesis & Catalysis, 2007, 349:1095– 1101. [2] H. Yano, J. Sugiyama, A.N. Nakagaito, M. Nogi, T. Matsuura, M. Hikita, K. Handa, Advanced Materials, 2005, 17:153-155. [3] W. Du, D.P. Curran, Organic Letters, 2003, 5:1765–1768.