Teaching Innovative Chemistry

In their recent Journal of Chemical Education paper, Slade, Pohl, and co-workers were able to develop a project-based laboratory series for the second semester of an introductory organic chemistry laboratory course designed for chemistry majors, incorporating the use of modern chemistry techniques. In this case, modern chemistry techniques included a MARS microwave for synthesis and fluorous technology for separation. A molecule was designed for ease of synthesis and purification via fluorous affinity chromatography, as seen in the scheme below. The students were challenged with developing a synthetic route to a target molecule, with some intermediate guidance. They were given support from the staff and allowed some time during the lab course to search for reaction conditions. The students found conditions in the literature and were challenged to modify them for use in a 3 hour laboratory setting (with some exceptions that were clearly communicated in the ground rules of the exercise).
The first challenge the students faced was the long reaction times of many of the literature steps. As they had been introduced to microwave chemistry using the MARS earlier in the semester, many of the students wanted to shorten the reaction time using microwave energy. The original (unoptimized) scheme developed by the teaching assistants prior to student introduction heavily relied on the use of microwave energy as a means to rapidly achieve each transformation (five of the six synthetic steps utilized the MARS Microwave System). Students were able to make the appropriate solvent and reagent choices and amounts based on work earlier in the semester, as well as literature information, just as they would in a research environment. They were also able to use workup procedures learned earlier in the semester. In addition to standard work-up procedures that would be learned in an undergraduate organic course (such as extraction and recrystallization), the students were also exposed to chromatography and other advanced techniques, such as a freeze-pump-thaw procedure.

525_photo_mars6_synth_teaching1_072ppi_-_copy.jpg As of publication, Slade, Pohl, and co-workers had attempted the exercise with two different laboratory sessions, the second evolving based on lessons learned from the first. They provide many different examples of how to customize the lesson for each class (from various teasers to aid students in their research to ways to shorten the synthesis for a shorter period of laboratory time) to more fully allow its adaptation in multiple different laboratory settings. While all of the students were not able to perform the full synthesis, they were able to perform at least several steps, including the final reaction to couple the perfluorooctylpropyl amine to the anthraquinone derivative. Performing the final coupling allowed them to generate the final product for use in the fluorous separation procedure, thus ensuring all major portions of the lesson were taught. Overall, student responses from the mini-session were positive. The students appreciated the freedom to design their own synthetic route and pursue it. Lessons were learned and standard research laboratory practices were applied, helping to better prepare students.