Organic Chemistry Mechanisms

A major concept that first semester organic chemistry students struggle with is using arrows to draw organic mechanisms. As drawing mechanisms is a fundamental way organic chemists predict products of a chemical reaction, understand stereochemistry, and apply to other aspects of a synthesis, it is fundamental that students be able to grasp the concept before moving forward to the second semester of organic chemistry and beyond. We sought to design an interactive, cooperative activity in which students could practice arrow-drawing mechanisms. The activity was broken into two parts. The first part involved sets of notecards, each set contained all the mechanistic steps necessary to accomplish a chemical reaction, printed in individual notecards. Students were tasked with putting the notecards in the correct order, i.e. assess what the arrows drawn on the cards indicated about the resulting product. Each pair of students were given a “beginner” set of notecards to begin; once they demonstrated mastery at that level (by checking their answers with a TA or professor), they could advance to a “intermediate” level set, and finally an “expert” reaction mechanism. In the second part, students were given a laminated sheet that had a complete reaction without any arrows. They were tasked with drawing the arrows in using a dry-erase marker, having to now demonstrate an ability to draw arrows to get to the indicated product. These mechanisms were again levelled so that students could work their way to more challenging problems. Students were asked to provide feedback via a survey at the end of the lab period. Overall, the student response was positive, indicating that they felt more confident about drawing arrow-pushing mechanisms than they did prior to the lab period.