Tetrabutylammonium Valinate Ionic Liquid Grafted Nano-SiO₂: A Novel Heterogeneous and Reusable Catalytic System for the Synthesis of Naphthopyran Derivatives Under Solvent-Less Condition

Abstract

In the present study, we have synthesized TBAVIL@nano-SiO₂ as a novel heterogeneous catalytic system by using tetrabutylammonium valinate ionic liquid (TBAVIL) and silica nanoparticles. The designed catalytic system is used for the preparation of naphthopyran derivatives by reacting substituted aromatic aldehyde, β-naphthol, and malononitrile in one pot system without the addition of solvent and co-catalyst. This method affords excellent yield (85–96%) of all the products with less reaction time (7–42 min). The catalyst reusability is also checked up to five cycles and found to have excellent activity up to three cycles.

Keywords:

• TBAVIL@nano-SiO₂tetrabutylammonium valinate
• ionic liquid ILs
• naphthopyran
• heterogeneous catalyst
• solvent-less

Acknowledgment

The authors wish to thank G.B.P.U.A. & T. Pantnagar for providing necessary research facilities, IIT, Ropar for providing NMR spectra, ISFAL Moga for Providing IR spectra, M. P. Singh, College of Veterinary, GBPUA&T for providing SEM and IIT, Bombay for TEM analysis, IIT, Roorkee for providing XRD spectra and DST fellowship for providing financial support.

Disclosure statement

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper. No potential conflict of interest was reported by the author(s).