An Inquiry-Driven Introductory Experiment for the Advanced Organic Chemistry Laboratory to Refresh Students on Fundamental Laboratory Techniques

Several fundamental organic chemistry laboratory techniques are introduced in the lower-division organic chemistry laboratory courses, and they form the basis for synthetic work students might encounter in future laboratory courses and research experiences. For those going on to take an upper-division organic chemistry laboratory course offering, several semesters may have elapsed since taking the lower-division equivalent. To refresh students on the fundamental techniques, we designed an introductory experiment for the upper-division course involving the open-ended structure elucidation of a trisubstituted benzene derivative. Students receive two samples of a 1:1 w/w mixture of an unknown organic compound and 4-hydroxybenzoic acid. They must purify one sample using acid–base extraction and the other sample using column chromatography, allowing for a comparison of the efficacy and efficiency of each technique. Finally, using data from 1H and 13C nuclear magnetic resonance spectroscopy, infrared spectroscopy, gas chromatography–mass spectrometry, and melting point analysis, they can elucidate the structure of their unknown compound. Based on the results of a written laboratory report, students demonstrated proficiency in identifying the unknown compound and articulating their corresponding deductive logic. Students also found the experiment to be a helpful review of concepts from the lower-division course and beneficial for their success later in the upper-division course.