Atom Economy is a measure of the efficiency of a reaction. Atom economy, in contrast to percent yield, takes into account all of the atoms involved in the reaction. This provides the chemist with a means to quantify how many atoms are turned into useful product vs. those atoms turned into waste.
The module begins with percent yield calculations for a nucleophilic substitution reaction. This is followed by a calculation of atom economy for the same reaction and a comparison of the results. There is detailed optional material covering "experimental atom economy" and "percent yield X experimental atom economy" calculations.
Atom economy is applied to the Green Chemistry Principles of preventing waste and maximizing the efficiency of a chemical reaction in a separate section. Other principles important in organic reaction chemistry (toxicity, energy requirements, feedstock origins, etc.) are discussed as well.
There is further discussion about atom economy related to addition reactions, elimination reactions, rearrangements and synthesis. The module includes "Notes to Instructors," a list of eight questions, a PowerPoint presentation and links to a variety of Presidential Green Challenge Awards.
Summary prepared July 2005 by Margaret E. Kerr, Department of Chemistry, Worcester State College.
Versions are available in Spanish and Portuguese.
Cann, M. C. Atom Economy: A Measure of the Efficiency of a Reaction. http://academic.scranton.edu/ faculty/ CANNM1/ organic.html (accessed June 2011).