When I was young my father and I shared a common interest of working on jigsaw puzzles. There was always a lot of variety in the pictures and we could easily pick different sections to piece together that would help the puzzle to take shape. The one that stands out clearest in my memory was called “San Francisco at Night” – it was 1000 pieces of black night sky interrupted occasionally with the light leaking from the windows of the buildings. Though I don’t remember ever discussing it, my Dad and I shared a characteristic of not wanting to back down from a challenge so there was never any doubt that no matter what we would finish the puzzle.

It strikes me today that the feeling we had looking at this foreboding puzzle of the night sky is the same feeling a lot of students have when approaching organic chemistry – and just like with the puzzle, successfully tackling organic chemistry depends on an organized plan of attack.

This “plan of attack” is one of the features that I particularly like about Organic Chemistry, Principles and Mechanisms by Joel Karty. I see a similarity between my puzzles and teaching the topics of substitution and elimination reactions. At first glance, the puzzle seems way too complicated; it only becomes manageable when we are able to see how to divide it into smaller tasks. This same approach is taken by Joel.

Where my father and I organized pieces showing different shapes and colors, Joel takes the basic steps of organic reactions and teaches them in their own chapter, Chapter 7, with a similar approach. In my experience, this focus allows for a much smoother transition from topic to topic as a class progresses through subsequent chapters – each new reaction is now recognized as a combination of other simpler pieces instead of a singular new fact to memorize (which is how I remember approaching organic as a student). Often just referring to identifying areas that are electron-rich or electron-poor (or HOMO/LUMO if you delve in to Interchapter D) can guide students into recognizing the reaction mechanism.

Just as my Dad and I were able to see our puzzle buildings and stars take shape, Joel builds on reaction steps to generate multi-step mechanisms for substitution and elimination reactions (Chapter 8). I often find that students are drawing their own correct conclusions about these reactions well before we discuss certain details. For example: competition between substitution and elimination reactions is not discussed in the text until chapter 9 but often students have already recognized trends in issues like substrate character and in nucleophile and/or base strength!

hands and puzzle pieces
Image by Luis Francisco Cordero

Before you know it students are confidently arrow-pushing their way through complex mechanisms or the puzzle is completed, glued together and hanging on the wall – and it’s time for the next challenge.

-Don Carpenetti, Craven Community College
Click here to learn more about Professor Carpenetti

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