Organic chemistry nightmare.

Pre-Med & Medical School Pre-Med Topics
1

<p>I was wondering how all you people who did well in o-chem studied? Organic chemistry has been a complete nightmare for me. I took o-chem 1 last semester and received a C. It put a large dent in my GPA. The sad thing is that I studied so much for that class and it was still not enough. This is the only class that I have trouble with. Physics and gen-chem were in my opinion easy and I easily scored As in those classes. I'm now taking o-chem 2 and it looks like I'm headed for a C again. For the last mid-term I studied an insane amount (6 hours/day for 5 days) and received a C. This has led me to conclude that my studying method is improper/ineffective.</p>

<p>For those who have done well in organic chemistry/know someone who did well, what was your/their study method? Flash cards? Practice problems? A better book?</p>

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<p>I did recently come across this hint…</p>

<p>Don’t only memorize reactions but also focus on following the electrons.</p>

<p>If it helps, good. If not, ignore. lol</p>

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<p>Well I guess that is partially helpful because I was completely memorizing reactions… but how is one supposed to “follow” electrons when pretty much anything can happen. Sometimes that carbonyl group gets protonated, other times the hydroxyl group gets protonated. It just seems all so random…</p>

4

<p>the kid with the highest average in orgo that I knew would literally just sit down with all the lecture slides and click through them at a pace of about 2 slides/second. He averaged in the mid to upper 90s while the class average was in the 60s. Does that help? lol.</p>

<p>Honestly, there can be so much variability in orgo teaching that you’re going to have to talk to kids at your school. Even what mom2 said wouldn’t have been much help for my class. The vast majority of the tests were just synthesize A from B. This is in stark contrast to the orgo on the MCAT where I would say memorizing is enough.</p>

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<p>Electron orbital hybridization models, sp and sb filling, critical angles</p>

<p>There are reasons (based in physics, esp quantum mechanics) why reaction occur. They are not random.</p>

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<p>I tried searching for explanations based on physics, but there are simply to many factors that effect the reaction. For example, in one reaction the product may be destabilized by angle strain but stabilized by resonance… which one wins out? This is why I find it so hard to predict a reaction in organic chemistry :(. It can usually only be explained after the product is isolated.</p>

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<p>1) Talk to your professor every week. Go to office hours. Be friends with your TA.
2) Study with people who are doing well.
3) Do as many practice problems as you can, and then do ten more.</p>

8

<p>Does your professor give a particular type of exam? Mine has a nomenclature section, mechanism section, reactions section, synthesis section and miscellaneous section. </p>

<p>So I’d make a big list of all the reactions, reactants in the left and products on the right and cover half the page to learn the reactions.</p>

<p>I’d memorize the rules for nomenclature, and go into the book and do every problem on naming things to study for the nomenclature.</p>

<p>I would find the general patterns for mechanism and learn which patterns goes with which reaction. I’d then get blank paper and write out the mechanism and check my work until I get them all right. That’s the mechanisms covered. </p>

<p>For synthesis I would just practice problem in the book. All you do is take things apart and think of the reactions you know to build it up.</p>

<p>Lastly I’d go through all my notes and the book to find all the miscellaneous facts such as NMR, IR, etc numbers and anything that stands strikingly out and make a flashcard of it.</p>

<p>I’m an A-/B+ ochem student and I study about 50-60 total hours for each exam. Save all your materials for each exam and use it to study for the final.</p>

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<p>Can the Ochem experts here comment on the chain of Ochem comments found below? </p>

<p>It starts with an OP having troubles…</p>

<hr>

<p>Sometimes the carbonyl group (C=O) gets protonated, other times the hydroxy group (C-OH) gets protonated and leaves… both of these happen in water/acid. There are a bunch of other examples where I’ve always wondered “why doesn’t this happen instead…”.*</p>

<p>To those who did well in organic chemistry: did you just memorize the reactions or is there some way to actually predict whats going to happen despite everything seeming so random?</p>

<hr>

<p>You have to understand it man. Memorizing the reactions will just confuse you. You just have to understand what happens in base and acid catalyzed rxns. If you don’t understand basic acid/base stuff then go back to your basics and practice!</p>

<hr>

<p>It’s crazy at first, but there is a method to the madness! Try “ochem as a 2nd language” and be comfortable with the rules of acidity.</p>

<hr>

<p>Both carbonyls and alcohol groups can be protonated - carbonyls are more basic (more likely to be protonated) because carbonyls have a resonance form where there’s a negative charge on the oxygen.*</p>

<p>Also, alcohol groups, when protonated, MAY be a good leaving group (water!), depending on the solvent or the rest of the molecule structure.</p>

<p>Like everyone else has said so far - there really is a method to the madness. Do not try to memorize things by rote - it will make you miserable and hate the subject even more.</p>

<hr>

<p>What everyone else said. Keep practicing those mechanisms, and remember general rules and trends.</p>

<hr>

<p>a carbonyl group does not mean carboxylic acid (o resonance) and even then we are talking about protonation, not<em>deprotonation</em></p>

<p><a href=“http://evans.harvard.edu/pdf/evans_pka_table.pdf[/url]”>http://evans.harvard.edu/pdf/evans_pka_table.pdf&lt;/a&gt;&lt;/p&gt;

<p>look at pka of conjugate acids of methanol and the ketone listed, similar species will follow the same trends listed here</p>

<hr>

<p>If you understand equilibrium, it’s not really random. The carbonyl can be continually protonated/deprotonated in solution and there is some mix of both forms, but the deprotonated form predominates. Same for the alcohol.</p>

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<p>The thing about organic chemistry is yield. Sometimes when you learn a certain reaction has a certain product, the reality is that only 70% is the desired product and the rest is where stuff went wrong, and you have side reactions. A carbonyl is less hindered than a hydroxy so more often than not it gets protonated. Yet there is still a yield of the other product, although it is more minor. </p>

<p>I think you’d try to go crazy understanding enough of the rules to realize when one thing happens over another so sometimes maybe memorization is the best option?</p>

<p>For example, if you get a super high yield in an ochem lab, there is reason to be suspicious.</p>

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<p>@maverick137: Thanks, I guess I simply didn’t study enough time. You studied 50 - 60 hrs and I did something like 30 - 35 :. I will try learning the material the day it is taught in lecture and NEVER NEVER procrastinating in o-chem. It’s kind of insane how this much work is required for a 3 credit o-chem class when there are so many other 3 credit classes that require a fraction of the work. o-chem should be like 5 credits lol. </p>

<p>@mom2: That’s the other thing about o-chem that I dislike, everything is pretty much impossible to predict :(.</p>

<p>I guess what I’ve learned so far is that I should NEVER procrastinate in this class and that I should study even more.</p>

<p>If anyone else has any other advice/wants to post how they study for their o-chem class, please do!</p>

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<p>Last bits of advice. Try to read the chapter before the day it is covered in class. </p>

<p>And studying is not staring at something in a daze. Take breaks when needed. 50 minutes of studying followed by a 10-15 minute break might be more useful than just straight studying. If you aren’t focused and absorbing your just wasting time.</p>

13

<p>

Ok.

It’s not too hard. In acidic conditions the carbonyl is protonated first. This doesn’t happen in basic conditions. The hydroxyl group is protonated to make it a better leaving group (every time you get a situation where a nucleophile attacks and you have a hydroxyl group leaving, you need to protonate it first, except in the E1cB mechanism for the dehydration of the aldol product).</p>

<p>How do people know these things? In my advanced organic class we explain it using things like MO theory and HSAB theory. However, you won’t use this in your lower division classes so it’s just memorization. Proton transfers are acid base reactions, and you can tell whether an acid base reaction is favorable or not from pKas (so you can memorize them). Also, acid base reactions are faster than C-C bond formation reactions, so that’s why they occur first. You can also memorize a list of leaving groups and which ones are good or not.</p>

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<p>If you follow my advice, you will do a lot better in Organic Chemistry.</p>

<p>1) Get “Organic Chemistry as a Second Language” by Klein and work through the book meticulously. </p>

<p>This book presents O-chem in such a logical and easy to follow manner. I cannot recommend this book enough. Thousands of others can attest to the helpfulness of this book.</p>

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<p>D. just had to work harder, that has been working for her so far. Anyway, Orgo is still easier than Med. School academic material. She mentioned that studying for one Orgo exam was taking about 30 hours. You can do it in your head while doing something else (walking between classes, gym…cooking, shopping). The last is a great habit that has been utilized in Med. School all the time as D. is walking most of the time to her school. Conceptual is easier for her also, there is not that much conceptual material in Orgo (according to her). But she got her A and a decent MCAT score despite the fact that she did not like it, she loves Gen. Chem though, her favorite class. Keep in mind that Orgo is on MCAT.
I do not believe in any tricks, just push harder.</p>

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<p>Unfortunately there seems to be a high degree of variety in the curriculum in Orgo. My Orgo 1/2 class were reasonably difficult and prepared me well for the ACS standardized test, but we focused almost 100% on mechanisms, not critical angles, orbitals, or any of that.</p>

<p>There are ways to predict what kind of reaction will happen - Ask your teacher, he/she will explain. For example, steric hindrance is a huge factor when deciding what kind of reaction will happen. Acidity and Basicity are other factors, as are the solvent involved (i.e. did you know a polar protic solvent like H2O will stabilize a carbocation, thus promoting Sn1 or E1 reaction rather than Sn2/E2?). </p>

<p>For me, I would go through old exams that the professor would put up online. I would do them over and over until I was blue in the face. Do enough mechanisms where you consistantly get them right. I also went to office hours every week without fail to keep up with what we were learning. This seemed to be alright for me, the only thing I never really became fully comfortable with was stereochemistry (I’m terrible with spatial stuff like that!), but I ended up getting As in Orgo 1 and 2.</p>

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<p>*If you follow my advice, you will do a lot better in Organic Chemistry.</p>

<p>1) Get “Organic Chemistry as a Second Language” by Klein and work through the book meticulously. </p>

<p>This book presents O-chem in such a logical and easy to follow manner. I cannot recommend this book enough. Thousands of others can attest to the helpfulness of this book.*</p>

<p>I have heard this book recommended again and again. If I had an incoming premed student, I’d get it.</p>

18

<p>The only thing that is really important beside the grade is an MCAT prep. So, whatever it covers, it is better be good enough for the MCAT.</p>

19

<p>I second the person who recommended “Organic Chemistry as a Second Language.” My friend, who withdrew from Organic Chem last semester, is now taking it again and he is using this book. So far, he found the first exam easy (and averages for Organic in our school are around high 50’s and low 60’s.) Of course he studied very hard as well, but having this book gave him that extra push needed to go beyond a C and get to a B+ or A.</p>

20

<p>A good friend of mine studied primarily from orgo books, including the one our course used written by “Aunt Janice” Gorzynski-Smith. His reliance on text books was clear when he called them “carbo CASHUNS” instead of “carbo CAT IONS.” It’s been 4 years, and we still chuckle about that one on a shockingly regular basis.</p>