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Learning Reactions: A Checklist (PDF)

Let’s Get More Specific About Where Memorization Works And Where It Doesn’t

Recently, we tried to understand what instructors mean when they say, “Don’t Memorize!”, or its darker variant, “If You Try To Memorize Everything You Are Doomed To Fail“.  You can read the whole post here, but it basically boiled down to this:

Brute force memorization of a large number of reactions and mechanisms is not efficient. If there are a lot of reactions and mechanisms to learn, spend significant time analyzing the common patterns. Like mlukeman said: “A terrible way to become good at chess is to watch a bunch of pro games and try to memorize the pattern of moves in each game. You instead need to understand the general principles that led the players to make those moves in the first place.”

Still, in some Org 1 courses, you might be able to get away with memorizing reactions and mechanisms without understanding them, especially if you’re not tested on a deep level. Where the “Doomed To Fail” narrative really kicks in if you try to apply this strategy to Org 2, which is largely wall to wall reactions (>100, easily). Hence the advice: Learn the concepts, don’t just memorize reactions.

• Although some instructors would be loath to admit it, if you spend some time memorizing things like functional groups, a few useful pKa numbers, electronegativities, and so on, you are not “Doomed To Fail”, because memorizing these items is not that time-intensive.

Still, this doesn’t seem specific enough. It’s hard to visualize for a beginner. If I were taking organic chemistry over again, a detailed roadmap of what to expect would be useful.

So I thought it would be helpful to take a common problem students face – learning a new reaction – and break it all down into some very specific things to learn. You can think of this as a checklist, if you will.

I even made a free PDF of what I cover in this blog post, which you can download here
(Download Reaction Checklist PDF)

What makes organic chemistry very different from most science courses is that there are many different categories of material to learn.

On the PDF, I’ve included a checklist of typical “facts” that one commonly wants to learn about a given reaction.

The PDF includes a list of important skills one should practice in order to confidently be able to understand a reaction, such as calculating formal charge, interconverting resonance forms, recognizing implicit hydrogens and lone pairs, and many others.

I’ve tried to include some of the key concepts for learning reactions on the sheet. The good news is that  there are a finite number of important concepts that will help you carry most of the freight, just like there are a finite number of important concepts that mechanics use for understanding engines, or chess players use for understanding positions on the board.

The bad news – for memorizers, anyway – is that if your instructor tests you on your ability to apply concepts to various reactions, there is a near-infinite number of questions they could ask, and it’s impossible to prepare for a test like this by memorization. The only way is to do a lot of advanced problem solving and gain practice by making a lot of mistakes.

To help things along in this regard, I’ve included a suggestive list of “deep” conceptual questions that you could try asking yourself about a new reaction, once you’ve understood it at a “factual” level.

Much as someone who understands how a lawn mower engine operates can apply some of the same concepts to, say, understanding how tractor and automobile engines work, if you keep asking these types of deep questions, you’ll eventually find yourself with a excellent mental “working model” of how organic chemistry reactions work that you can apply to other new reactions that you encounter.

The sheet also includes some “deeper’ questions to ask yourself about mechanisms, and finally, a few bonus exercises that will be useful for synthesis.

Download The Reaction Checklist PDF here

Thanks to Hubert Muchalski (@muchalh) and r/chemistry for helpful discussions. I’d appreciate any feedback to make this better.

 

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