Microwave-Assisted Synthesis and Pka Determination of Umbelliferone: An Experiment for the Undergraduate Organic Chemistry Laboratory

Abstract

A synthetic procedure for obtaining the fluorescent coumarin umbelliferone (7-hydroxycoumarin) and its spectral parameters were fully developed aiming at an undergraduate organic chemistry laboratory class. Umbelliferone is traditionally prepared via Pechmann condensation using malic acid, resorcinol and sulfuric acid as catalyst. The use of domestic microwave oven and the absence of solvent allow our methodology to be simple, fast and easy applied in obtaining umbelliferone at organic chemistry laboratory being greener than classical techniques of synthesis. In this class the student will learn how to measure the potency of a microwave oven, the applicability of this kind of irradiation in the organic synthesis of fluorescent compounds and how to determine the pKa of an organic compound through an UV/VIS spectrometric analysis. These experiments were designed to be suitable for a second and third year undergraduate curriculum.

Evaluation of Brazilian Contribuiton to Sustainable Development Through Microwave-Assisted Organic Synthesis

“…Microwave-assisted organic synthesis has grown in recent years. The use of microwaves in organic synthesis presents significant improvements when compared to conventional heating, as it presents selective heating, reduction in reaction time, greater conversion, and the possibility of not using solvents [10].…”