Uncatalysed Production of Coumarin-3-carboxylic Acids: A Green Approach

Abstract

A green contribution in short reaction times with moderate yields to produce coumarin-3-carboxylic acids is offered. Five different modes to activate the reactions (microwave, near-infrared, mechanical milling, and ultrasound) were compared with mantle heating in the presence or absence of ethanol, a green solvent. Near-infrared and microwave irradiations deliver the best yields in contrast to ultrasound and mechanical milling; moreover, these four processes offered shorter reaction times in comparison with the conventional mantle heating method. It is also important to highlight that the obtained molecules were produced without the requirement of a catalyst and two nonconventional energies forms are presented as new processes.