In this experiment, a safer, solid bromination reagent (pyridinium tribromide) and a more benign solvent (ethanol) are employed to green the reaction and provide an effective bromination of an alkene, stilbene. Although bromination of alkenes is an important reaction in organic chemistry, the standard procedures involve the use of liquid bromine and chlorinated solvents. The traditional reagent and solvent present serious safety concerns, health risks and environmental impact. The solid reagent and ethanol solvent significantly decrease the hazards associated with the exercise. On the other hand, the use of the pyridinium tribromide decreases the atom economy of the reaction. This compromise spurred the development of a (yet) greener bromination experiment involving hydrobromic acid and hydrogen peroxide. The link to the laboratory procedure includes post-lab questions.
Summary prepared July 2006 by James E. Hutchison, Department of Chemistry at the University of Oregon.
Doxsee, K. M.; Hutchison, J. E. Green Organic Chemistry - Strategies, Tools, and Laboratory Experiments, Print 2004; pp 120-124.