Chapter 7 in Karty’s book struck me as very unique when I first reviewed it. Initially, I considered it to be just an overview chapter that I could breeze through without much thought. After further review, I thought perhaps it covered too much material and would cause students to be confused rather than deepen their mechanistic understanding. As with any major curriculum change, I just had to teach it in class to determine the benefits.
Once I actually taught Chapter 7 in class, I realized how much I had underestimated its value. Coming from a traditional, functional group based approach to teaching organic chemistry, it seemed crazy to me to introduce students to every elementary step that the students would ever encounter all at once. Especially during the first semester. The text also introduces language to describe each elementary step that may initially seem odd to the average organic chemist. For example, I’ve always taught the E1 mechanism as a single mechanism rather than separating the individual elementary steps, heterolysis and electrophile elimination, into their own categories. What I discovered is that this initial focus on elementary steps proved valuable throughout the course as I could refer to them in any mechanism discussed after chapter 7. By introducing the 10 major elementary steps early, complicated mechanisms could be broken down into digestible chunks for the students. It increased the students’ understanding of mechanisms overall and improved their arrow pushing skills on quizzes and exams. I was most impressed with their ability to correctly add curved arrows to very long, complicated mechanisms and to identify the elementary steps by name, all by the end of Ch. 7!
The other thing I love about chapter 7 (and the book in general) is the emphasis placed on addressing common mistakes and overlooked questions. By color-coding the electron rich (red) and electron poor (blue) regions of molecules, students can more easily identify nucleophiles and electrophiles to determine the direction of electron flow. This emphasis on drawing curved arrows in the proper direction significantly reduced the number of “backwards arrows” drawn by my students. In addition, many of the textbooks that I have used previously gloss over seemingly minor details like spectator ions. We all know that they are commonly omitted from organic reactions, but students are always wondering, “what happened to the sodium ion?”. While it’s something that I’ve always discussed in my courses, I was happy to see it addressed in the textbook for additional reinforcement.
Chapter 7 is a truly unique and valuable chapter, and I’m so happy that I took the risk to change my approach to teaching organic mechanisms. With the new release of the 2nd edition of the book, the changes Karty made to Ch. 7 only serve to enhance student understanding. Additional emphasis has been added to address common mistakes before they become bad habits. There are also more “Connections” boxes with interesting tidbits to connect the lesson to everyday experiences. I’m looking forward to incorporating these new additions into my lessons. If you haven’t already, give Chapter 7 a chance and perhaps it will become your favorite chapter, too.
You can read Chapter 7 from the new Second Edition under the “Sample Chapter & TOC” tab at the top of the page.
-Dr. Anne Szklarski, King’s College
Click here to learn more about Dr. Szklarski
I’m just getting into this chapter with my students, but I expect that I will find the same thing you do: cutting mechanisms down into bite-sized chunks will be a great help to them.
I have already told them that Chapter 7 is crucial to their understanding anything in the rest of the course.
The section near the end, 7.8 is my favorite. That section really encapsulates the explanations for reactions that we use in all of the later chapters.