Your back’s against the wall. Your time is limited, but you’ve got to make a move. You’ve got to do something…but what? This move could make or break you…bring home the win, or send you back to square one. How do you respond?!
To some, the previous paragraph may sound like a scene from an action movie or the climax of a classic sporting event. Students of organic chemistry may find it eerily similar to the feelings they experience during examinations…and chess fanatics out there might hear echoes of their emotions at a critical moment during a chess game. The core idea that unites all of these scenarios is the pressure of prediction—the emotional roller coaster associated with predicting the future. Using our observations of the past to predict the future and choose a “move” is a key skill involved in science, sport, chess and staying alive in an action movie.
Prediction cannot happen without rhyme or reason! Unlike the base instinct for self-preservation modeled by most action heroes, chess and organic chemistry have rules. The rules delineate what we can and cannot do, and thus help limit and direct the thought process. In chess, the rules are very clear: no two opposing pieces can occupy the same square, the game is over when one side’s king is captured, etc. To a master of organic chemistry, the rules of organic chemistry are just as clear: orbitals must overlap for reactions to occur, carbocations cannot serve as electron sources, etc. To a novice of organic chemistry, these rules are understandably much less apparent…worst of all, most instructors of organic chemistry make little to no effort to remedy this problem in the classroom.
Organic chemistry is rarely taught in a way that promotes understanding and creative application of the rules of organic chemical structure and reactivity.
Let’s return to chess for a moment. Hundreds of years of instruction and study have been devoted to the still imperfect art of helping a novice become a chess expert. One thing that has become clear: simply knowing how to play the game is not enough. Seeing and executing creative applications of the rules of chess (tactics, strategy, etc.) lead to mastery. Similarly, knowing how to push electrons will not make you an expert on organic reaction mechanisms…but knowing these “rules of the game” is an absolute pre-requisite for organic chemical mastery! Most students are never even exposed to the rules of organic chemistry in the classroom. Professors complain when they see students draw arrows issuing forth from protons, but they don’t teach electron flow as a well-defined system bound by rules…how can students in those professors’ courses be expected to learn the subject deeply or, God forbid, master it?!
The first exposure students get to organic reaction mechanisms typically involves acid-base chemistry. They are given a few mechanisms involving proton transfer in class, then asked to draw mechanism after mechanism involving proton transfer over a few days. This teaching method is the chemical equivalent of making a class F chess player memorize the full collection of Tal’s attacking games. Will the student be great at winning attacking positions after this exercise? Of course. Will he have a broadly useful understanding of chess? No way—in fact, he’ll probably turn into an attacking zombie who whines and (here’s the kicker) fails when facing positions where defense is critical. Organic chemists can probably see where I’m going with this. Students who have practiced with nothing but “lone-pair-grabs-proton” mechanisms will be flummoxed by protonation of the π bond (which, ironically, is what usually comes next). Don’t even think about the σ bond as a nucleophile! Learning organic chemistry this way, it’s difficult to gain a broad appreciation for the subject—and to meet new structures and reactions with confidence.
Why not teach what’s possible before digging into the gory details of what’s real? Isn’t making the possible into reality one core goal of practicing organic chemists, anyway? The concept of the advance organizer comes to mind: given a framework for organizing knowledge at the outset, students find it much easier to learn, recall, and use information later. For example, armed with an understanding of the general classes of organic reactions, the student is more likely to put Dess-Martin periodinane on the same mental shelf as Swern conditions: the oxidation shelf. That same student would probably also have an easier time planning her next “move” in a synthesis requiring oxidation (see what I did there?).
Chemistry and chess are both about prediction, and prediction is hard. It takes years to master, no matter how it’s taught. Still, the next time you ask students to make a prediction, consider how the pertinent information, patterns, and skills are arranged in your own mind, and make that organization as clear as you can to your students! It’s working for the best chess coaches… (If you’re a chess player, click the link. Silman’s imbalances are an awesome advance organizer for chess.)