For most of my teaching career I have organized my course by mechanism class rather than by functional group. Even so, year after year I observed my students struggling with reaction mechanisms. Neither elaborating mechanisms on the board in class nor assigning challenging mechanism problems in practice or homework sets seemed to improve my students’ ability to demonstrate mechanistic competencies on exams, especially when it came to mechanisms that were not direct analogs of those discussed in class or in the text. A simple, foundational pedagogical change in Joel Karty’s forthcoming textbook, however, helped me to break through this barrier and reach my students.
When I first became aware of Joel Karty’s forthcoming textbook, I was excited about its mechanistic organization. While all contemporary texts pay significant attention to reaction mechanisms, most are still organized by functional group reactivity patterns rather than by mechanism class. Joel’s early chapter devoted to common elementary steps especially intrigued me. To be frank, while I teach a mechanistic organization, I was skeptical of devoting class time to disconnected elementary steps that were not always linked together into cohesive mechanisms. After having used the Preliminary Edition, I can say now that my skepticism was unfounded as this chapter (Chapter 7) has changed my students’ performance and has also allowed me to promote active learning.
When I first reached Chapter 7 last fall, I made brief mention of the elementary steps and then directed my students to study the remainder of the chapter on their own. While I didn’t spend significant time discussing the chapter, I referred back to it every day. When I elaborated a new mechanism, I paused after every step and asked students to speculate as to what the next likely step(s) could be based upon the elementary steps developed in Chapter 7. To aid their analysis, when we discussed mechanisms in class, I projected a graphic that illustrated these common elementary steps. The response to this methodology was so positive that I continue it to this day.
I observed that this simple change in my teaching style, which was enabled by a foundational pedagogical commitment of the text, has increased engagement and decreased anxiety on the part of my students when it comes to reaction mechanisms. For example, the oxidation of a secondary alcohol involves elimination from a chromate ester to afford a ketone. This year, when we discussed the mechanism by which the chromate ester forms the ketone, my students jumped to suggest an E2 pathway. They made this connection much more readily than in the past, and the connection itself to material that they learned earlier made this new reaction less intimidating.
While my students have also shown improvement on exam problems that involve mechanisms, as equally important to me as an instructor is that I see in my students an increased ability to both recognize elementary steps and to actively engage in the elaboration of reaction mechanisms.
— Brad Chamberlain, Luther College
Brad Chamberlain teaches at Luther College and is currently class-testing the Preliminary Edition of Joel Karty’s forthcoming textbook. Click here to learn more about Prof. Chamberlain.