So you’re a pre-med or a chemistry major or minor. Why else would you be taking orgo (or o-chem, if that’s what you prefer)? Well, perhaps you’re just one of those geniuses (geniusi? genii?) who takes hard courses for pleasure, and in that case you probably don’t need to read this. You probably don’t even need to read the textbook, for that matter. Joking aside, organic chemistry is widely known for being one of the most difficult courses in college, if not the most. In all honesty, I disagree – while it’s not the easiest by any stretch, it is certainly not the hardest…or at least, it doesn’t have to be.
The first thing that is helpful in orgo (or in any class) is to have a broad overview of what organic chemistry is all about, where the course is going, and the scope of the material that will be covered in the courses (organic is normally offered as a 2-term sequence).
While I can’t speak for all organic course curricula at every university with every professor, I think I can generalize what most organic courses will cover. Organic chemistry is a hugely broad and growing field, and introductory courses typically cover the very basics. In a nutshell, here’s what happens: you review basic concepts in general chemistry, you learn about stereochemistry (basically, geometric possibilities), spectroscopy (techniques to analyze/identify a sample), and then from there on out it’s just reactions. “Reactions” means mechanisms (the step by step of a reaction), and also synthesis problems (use whatever reactions you know to make some big molecule).
First, you will learn general concepts, many of which cross over with general chemistry. Ideas like equilibrium, kinetics, bond theory, acid/base chemistry, resonance structures. These ideas are covered extremely quickly and broadly, and honestly they do not figure a great deal into the bulk of the organic chemistry you will learn. The take home message here is definitely to have a general idea of what the concepts are, but don’t worry about specific formulas, calculations, definitions, etc. Organic is all about the reactions, and occasionally you will learn one reaction where, say, changing the pH will significantly affect the equilibrium. So really, these general concepts are relevant only in isolated incidents, so to speak, and you should learn them to the extent required to understand the context in which they appear. However, there are two concepts that are exceptionally important: resonance and sterics (more on this later).
Stereochemistry basically requires that you have some spatial ability, especially to visualize 3D configurations. Stereochemistry basically boils down to a few vocabulary terms and some nomenclature to memorize. Here is one place you want to have definitions down pat. For example, know that an “optically inactive” sample does not always have to be an “achiral” compound – it could be a 50-50 mixture of enantiomers. Applying the terms to describe a given molecule is somewhat more demanding, but that is really the extent of what you have to know/do. In the big picture, stereochemistry only plays a role in a select few reactions or structures that you will come across, so don’t sweat it if you’re really spatially challenged.
Spectroscopy can be tricky, and, like stereochemistry, it will carry on throughout the rest of the course, perhaps moreso. Basically it’s analytical techniques where a big machine scans a sample and gives you a spectrum, which you learn to interpret and say what the sample was. What this boils down to is looking for characteristic peaks (e.g., this broad, strong peak at this position mean’s it’s an alcohol) and in the case of H1 NMR, looking for split patterns. It’s not incredibly difficult, but it can get tricky at times. Also, professors vary greatly on this topic. Some will make you memorize a lot of characteristic peak positions for functional groups, while others will provide you with a table with everything you need. But make sure you have a good idea of how to analyze spectra, particularly IR and H1 NMR. There will likely be at least 1 spectroscopy problem on every exam from here on out.
Finally, you’re in the bread and butter of organic chemistry: reactions. This is just memorization for the most part, although you will definitely notice some patterns. The best advice I have is to make your own study guide, a summary of all the reactions you know, including their mechanisms. You may want to make 2 versions of the guide: one with just the reactants, reagents, and products, and another with the full mechanisms. Another helpful guide to make when the reactions pile up is a “How to make X” guide; e.g., make a list of every reaction you know to make a carboxylic acid. This organization is extremely helpful when you go to do synthesis problems.
But the point here is to start early! Make this list as you go along, even after the class you learned the reaction in. It’s not time consuming at all, but if you wait for exams to start looking back and summarizing everything, you will doubtless feel overwhelmed. The majority of the problems on exams in 3/4 your organic career will most likely be of these types: fill in the blank (product, reactant, or reagent, given 2 of the 3), synthesis, and show the mechanism for this reaction. Knowing reactions well will allow you to do well on the first 2 types of problems (1st is plain regurgitation; synthesis done backwards is like regurgitation where you’re given the product but need to come up with reactants and reagents). Of course, you still do need to be aware when regurgitating that some reactions have “catches”, or special conditions/facts. Note this down in your study guide as relevant. The mechanisms are arguably the hardest part of organic. You will definitely see patterns, but can be woefully stuck when asked to figure out a mechanism for a reaction you’ve never seen before. My best advice is to think about what has to happen, and what is plausible (e.g. looks like/is something you’ve seen elsewhere). An extremely useful concept in these cases is to think about charge distribution, which you will gradually get an idea of as you progress and see more reactions. This will tell you what is likely to attack where.
I alluded to this earlier: sterics and resonance. These concepts are probably the two most widely applicable concepts in solving organic problems, particularly the open-ended kind where you are asked “why is x more acidic than y”, or “why does x react like this but y react like that”, etc. Any time when you approach an open ended question, the answer is almost guaranteed to have something to do with sterics or resonance. Remember, the more resonance structures you can draw for a particular compound (or intermediate), the more stable (favorable!) it is. This touches on one important overarching theme: favoring stability. Anything that affords a compound stability will be favored. Often this is resonance structures, but it could also be aromaticity, separation of charge, etc. On a completely unrelated note, if nitrogen is involved in an open-ended question, the answer may involve the difference between sp2 and sp3 hybridizations (sp2 has more s character and thus the bonds are shorter and stronger).
As an ending note, here are some other tips for surviving organic chemistry:
1. If your textbook confuses you, find another resource! There are lots of Web sites with visuals/explanations that will help, and often you may find that a different presentation of material will just make more sense to you. Organic curricula are pretty similar in terms of the detail they go into, so most of the resources you dig up will be at your level of study.
2. Work practice problems! Memorizing reactions is often not enough; you need to know how to apply the knowledge. Sometimes there are tricks/shortcuts you will discover when practicing. You might even find that you’re misunderstanding some concept, and better to trip up on a practice problem than to trip up on an exam. Don’t do problems exhaustively, though – there are useful problems to practice on, and then there is overkill that is guaranteed not to resemble anything you’d find on the test. In my opinion, the most useful problems are the ones similar to exam problems: fill in the blanks, syntheses, open-ended, and spectroscopy. Spectroscopy in particular will require a good amount of practice, as will syntheses until you get the hang of them.
3. Just to recap, start building your study guide early! As soon as you start learning reactions, put them down in a study guide. Build this as you go along, and you’ll always have a guide on hand to reference. This is especially useful because it will be tailored to the reactions your professor chose to teach/emphasize – this is not something you can simply find online.
4. Resonance and sterics! If you pay careful attention, you will find that 95% of everything you learn in orgo will boil down to resonance or sterics.
This guide is by no means exhaustive, but these are things that I wish I had known going into organic. My hope is that you take my advice and adapt it to your own organic experience, for you no doubt have different curricula, professors, study habits/skills, etc. But I know this is what worked for me, and hopefully you will find a way to apply it so that you find something that works for you and makes the organic experience less painful. Good luck!
