Aerobic alcohol oxidation using a copper(I)/TEMPO catalyst system: A green, catalytic oxidation reaction for the undergraduate organic chemistry laboratory

Abstract

Modern undergraduate organic chemistry textbooks provide detailed discussion of stoichiometric Cr- and Mn-based reagents for the oxidation of alcohols, yet the use of such oxidants in instructional and research laboratories, as well as industrial chemistry, is increasingly avoided. This work describes a laboratory exercise that uses ambient air as the source of oxidant and a readily available CuI/TEMPO catalyst system to convert benzyl alcohols to the corresponding aldehydes in standard glassware at room temperature. The procedure is well suited for a high-enrollment undergraduate course, and the complete exercise fits easily within a 3-h lab period. The structures of the organic starting materials and products are determined by NMR spectroscopy and EI-MS. The protocol is adapted from the contemporary research literature and provides students with practical experience of a modern, "green" oxidation method. In addition to the practical aspects, the experiment encourages student discussion and exploration of transition-metal- catalyzed reactions, a topic that is underrepresented in the contemporary undergraduate organic chemistry curriculum. © 2012 The American Chemical Society and Division of Chemical Education, Inc.