By James Ashenhurst

Last updated: February 1st, 2019 |

Love this quote, from Organic Chemistry 1 as a Second Language by David R. Klein (fuller review to come) on organic chemistry and memorization.

You probably know at least one person who has seen one movie more than five times and can quote every line by heart. How can this person do that? It’s not because he or she tried to memorize the movie. The first time you watch a movie, you learn the plot. After the second time, you understand why individual scenes are necessary to develop the plot. After the third time, you understand why the dialogue was necessary to develop each scene. After the fourth time, you are quoting many of the lines by heart. Never at any time did you make an effort to memorize the lines. You know them because they make sense in the grand scheme of the plot. If I were to give you a screenplay for a movie and ask you to memorize as much as you can in 10 hours, you would probably not get very far into it. If, instead, I put you in a room for 10 hours and played the same movie over again five times, you would know most of the movie by heart, without even trying. You would know everyone’s names, the order of the scenes, much of the dialogue, and so on. Organic chemistry is exactly the same. It’s not about memorization. It’s about making sense of the plot, the scenes, and the individual concepts that make up our story

If you had to draw an analogy between a film and a reaction in organic chemistry, how do they map? Here’s my two cents.

Plot – the bonds broken and formed

Characters – the atoms involved in the bond-forming and bond-breaking, with their “personalities” represented by how electron-rich or how electron poor they are. The key “motivation” of the characters is that opposite charges attract, and electrons flow from “rich” to “poor”.

Setting – in cases where the reaction could happen at multiple sites, it’s important to understand why it happens where it happens. In organic chemistry we call this “regioselectivity”. Markovnikoff vs. anti-markovnikoff addition to alkenes is an example.

A second aspect to “setting” is in understanding the stereochemistry of a reaction – that is, why it produces the stereochemical result that it does. Not applicable to all reactions, but many.

Lines – the “lines” are the reaction arrows that show the movement of electrons and the modification of charges.

Quoting it by heart – when you fully understand a reaction, you know the “plot” of a reaction flows naturally from the motivations of the “characters” in their particular “setting”, and describe how the plot moves forward by writing out the correct sequence of “lines”. Furthermore, you even can predict what will happen when this “setting” is changed.

It’s an imperfect analogy, I confess – there’s probably other people out there who could do a better job in translation! Thoughts?