Lactic acid as an invaluable green solvent for ultrasound-assisted scalable synthesis of pyrrole derivatives

Abstract

Lactic acid has been used as a bio-based green solvent to study the ultrasound-assisted scale-up synthesis. We report here, for the first time, on the novel and scalable process for synthesis of pyrrole derivatives in lactic acid solvent under ultrasonic radiation. Eighteen pyrrole derivatives have been synthesized in lactic acid solvent under ultrasonic radiation and characterized by (1)H NMR, IR, ESI MS. The results show, under ultrasonic radiation, lactic acid solvent can overcome the scale-up challenges and exhibited many advantages, such as bio-based origin, shorter reaction time, lower volatility, higher yields, and ease of isolating the products.

Keywords: Bio-based solvent; Lactic acid; Pyrrole derivative; Scalable Knorr condensation; Ultrasonic radiation.