Synthesis of a Bromoether from Trans-Cinnanmic Acid as a Sophomore Laboratory Procedure
For a number of years, students taking organic chemistry here at Ohio Northern University have routinely completed a standard laboratory experiment wherein trans-cinnamic acid is treated with highly corrosive liquid bromine. This chemical reaction results in the synthesis of a solid dibrominated addition product, which is isolated, purified, and characterized by the students. While chemists must learn to work safely with dangerous chemicals, it is prudent to improve the safety of procedures used by chemistry students whenever possible. Thus, an alternate reaction was developed that includes substituting liquid bromine with commercially available N-bromosuccinimide (NBS), which is a nonvolatile, relatively safe, solid reagent. Furthermore, the experiment helps students better understand (and remember) the reaction mechanism of haloether formation--a slightly more complicated reaction outcome than dibromonation due to the use of nucleophilic solvents in the reaction.