An Operationally Simple Aqueous Suzuki-Miyaura Cross-Coupling Reaction for an Undergraduate Organic Chemistry Laboratory

An experiment featuring an operationally simple Suzuki-Miyaura cross-coupling reaction suitable for a second-semester, second-year undergraduate organic chemistry laboratory course is presented. The cross-coupling reaction between 4-bromobenzoic acid and phenylboronic acid is run entirely in water and features an easily prepared and affordable palladium catalyst that requires no specialized equipment as the reaction can be run in a flask or beaker that is open to air. The product precipitates directly from the reaction mixture and is purified by a straightforward recrystallization from aqueous hydrochloric acid and ethanol. The cross-coupling reaction requires only 30 min of reaction time, allowing ample time to coordinate this reaction with other instructive exercises, such as recrystallization, melting point determination, and IR and NMR spectroscopy. The solvents used in the synthesis and purification provide a link to the growing commitment to sustainable chemistry in teaching laboratories and how safe, renewable solvents and catalysis play a role in green chemistry.