Xanthan Sulfuric Acid: An Efficient and Recyclable Solid Acid Catalyst for Pechmann Condensation

Abstract

In this report, substituted coumarins are formed via Pechmann condensation using various substituted phenols and ethyl acetoacetates in the presence of xanthan sulfuric acid as a solid acid catalyst under solvent-free conditions. This method is very simple, cost-effective, and has shorter reaction times, and the catalyst could be reused.

GRAPHICAL ABSTRACT

Keywords:

• Biodegradable xanthan sulfuric acid (XSA)
• coumarins
• Pechmann condensation
• solvent-free conditions

ACKNOWLEDGMENT

One of the authors, B. S. K., is grateful to the Council of Scientific and Industrial Research (CSIR), New Delhi, Republic of India, for providing financial support in the form of a senior research fellowship.

Notes

^a Yields refer to pure products and all products were characterized by comparison of their physical data, ¹H NMR ¹³C NMR, IR, and mass.

^a Mixture of phenol 1 (1 mmol) and β-ketoester 2 (1 mmol) was stirred at room temperature.

^b Isolated yield.

^a Mixture of phenol 1 (1 mmol), β-ketoester 2 (1 mmol), and xanthan sulfuric acid was stirred at room temperature.

^b Isolated yield.

Note. Reaction conditions: phenol 1 (1 mmol), β-ketoester 2 (1 mmol), and xanthan sulfuric acid (0.08 g) were stirred at room temperature.

^a Yields refer to the pure isolated recovered catalyst.