When I talk to other faculty who are using the Karty book I find that we share a love of Chapter 7. In this chapter, the most common elementary steps are presented, those being proton transfer, biomolecular nucleophilic substitution, coordination, heterolysis, nucleophilic addition, nucleophile elimination, biomolecular elimination, electrophilic addition, electrophile elimination, and carbocation rearrangements. Every multistep mechanism in chapters 8 through 26 is presented in terms of these 10 elementary steps (I always say 7 in class since they are in Chapter 7 and numbers are hard).
Presenting single mechanistic steps that are then built into multistep mechanisms isn’t groundbreaking. What is different about Joel’s approach is the consistency in which the approach is used. Every time a mechanism is presented the mechanistic steps are indicated with blue text under the reaction arrow. The first example is from Chapter 8 when multistep mechanisms are first introduced.
This mechanism is four steps and each of the steps is one of the elementary steps that the students were exposed to in Chapter 7. In teaching the content, I’m able to continually break down the mechanisms into these simpler steps which are easier to grasp. On an individual level, they are also easier to predict. Students need not predict the entire reaction, just the result of the next elementary step. Any task is easier if you just have to do it a little bit at a time.
What about the second semester when the mechanisms get gnarly? Elementary steps are still there to help! Below is the mechanism for acetal formation, all seven steps of it. By this time in the semester, students have done these steps hundreds of times (hopefully), so seeing them in another order isn’t a huge deal. The pain and suffering are removed, and they learn another way that carbonyls can react.
This consistency does pose a bit of a problem for students transferring into the course for the second semester. Teaching at a two-year college, I tend to get a few every year. Generally, the students are looking to earn a better grade than their previous attempt at the course. Since the elementary steps are consistently used throughout the book, I send new students to Chapter 7 before the semester begins and share with them that this chapter is the key to success for the semester. Generally, they heed my advice and they have a working relationship with the steps before the course begins. By the end of the semester, they are excited by how much more they learned the second time through the course with the elementary steps to guide them through the previously monstrous mechanisms.
– Heather Sklenicka, Rochester Community and Technical College
