Rapid Blue Bottle Experiment: Autoxidation of Benzoin Catalyzed by Redox Indicators

Abstract

© 2016 The American Chemical Society and Division of Chemical Education, Inc. Air oxidation of reducing sugar under alkaline conditions and air oxidation of ascorbic acid catalyzed by methylene blue are known as the classical and the green chemistry versions of the blue bottle experiment, respectively. We propose a faster alternative of the blue bottle experiment in which air oxidation of benzoin under an alkaline condition is the main reaction. In addition to methylene blue (for the blue bottle experiment), erioglaucine (FD&C Blue #1), indigo carmine (FD&C Blue #2, for the chemical traffic light experiment), resazurin (for the vanishing valentine experiment), safranine, phenanthrenequinone, and tetrazolium chloride also catalyze the autoxidation of benzoin. Similar to sugar/hydroxide and ascorbic acid/CuCl2 reactions, chemical pattern formations are observed in this benzoin/hydroxide system. Our colorful reactions and patterns open the possibilities for both pedagogical activities and future in-depth research.