Greener Solutions for the Organic Chemistry Teaching Lab: Exploring the Advantages of Alternative Reaction Media

Abstract

A major approach for implementing green chemistry is the discovery and development of synthetic strategies that reduce the quantity of solvent needed, eliminate it altogether, or rely on new reaction media. An increasing number of examples have demonstrated that greener reaction solvents or media can enhance performance as well as reduce hazard. Here we describe four experiments designed for the undergraduate organic chemistry laboratory that illustrate both enhanced performance and a greener approach: (i) a solventless aldol condensation that involves the reaction of two solid reagents, (ii) a solvent-free, room temperature Diels–Alder reaction followed by an intramolecular nucleophilic acyl substitution, (iii) a Diels–Alder reaction in water, and (iv) a Diels–Alder reaction in polyethylene glycol (PEG) that may be conducted using microwave heating. The alternative solvents or reaction media used in these experiments not only reduce the use of hazardous and volatile organic solvents but also enhance the transformations by increasing the rate of reaction or facilitating recovery of the product. These thoroughly tested laboratory experiments are convenient, inexpensive, and rapid, thereby providing an opportunity to introduce green chemistry into educational settings easily.