Highly efficient green synthesis of the photochromic spironaphthoxazines using an eco-friendly choline hydroxide catalyst

Abstract

A greener route for the synthesis of the photochromic spironaphthoxazines employing a highly efficient, biodegradable and recyclable choline hydroxide catalyst in an aqueous medium has been described. This methodology offers diverse advantages such as mild reaction conditions, short reaction time (1 h), excellent yields (up to 91%), and operational simplicity that make it a useful and attractive option for the synthesis of the spironaphthoxazines. The choline hydroxide showed excellent catalytic performance until five recycles without significant loss of activity. The structures of synthesized spironaphthoxazines were deduced by their ¹H NMR spectra and melting points.

Graphical Abstract

Keywords:

• Choline hydroxide
• biodegradable
• recyclable
• spironaphthoxazines

Acknowledgments

The authors cordially thank the Department of Dyestuff Technology, Institute of Chemical Technology, Mumbai, India for ¹HNMR and FT-IR analysis. The authors are also grateful to SAIF IIT Bombay, India for ¹HNMR analysis.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The authors acknowledge their sincere gratitude to the University Grant Commission (UGC), New Delhi for funding this research work under the scheme of Minor Research Project.