<p>I know why organic chem is so hard because I just went through it. A lot of people memorize things or patterns (biology) and other memorize equations. In organic chemistry it is completely different! You have to memorize not only a lot of reactions and various forms and groups but you have to be able to VISUALIZE them. This is why I was very good at orgo.</p>
<p>With math I need to visualize the line going to zero to find the limit of the sequence. With physics I need to visualize that when capacitance goes down, charge goes up if voltage stays the same. Most of the people (engineers or bio majors) don't visual math or phyics like I need to. Their brains mostly work with equations (so one variable goes down, another goes up, it's obvious, easy) or they can plug in numbers. But with orgo most of my engineer friends were like "Where are the equations?!" & "I can't visualize this!" It's a very much you get it or you don't type deal. You can learn others but with orgo it is very non-bell curve.</p>
<p>You might be able to fudge your lack of knowledge but since it isn't multiple choice (you will be expected to draw and explain) you often can't do that. They are often drawn-out (as in lengthy) and hard to visualize and that on top of memorizing all of the other information that is needed to solve the same problem. Also, although you will learn the reactions and how they work in class, applying them to a compound you have never seen or using them to go from one compound to the next (synthesis) can be very challenging. Orgo chem problems can be EXTREMELY hard.</p>
<p>For all of you who really want to know, here are some sample questions from my accelerated organic chem course with methods to solve and maybe even answers if possible (this is what ChemE's take but there were pre-meds in my course thinking this was going to help them on their MCATS [I know one got a D. Yikes!]):</p>
<p>1) Create the steps of synthesis (drawing the intermediates of each step) to get from (n-hydroxl-propyl)-cyclohexane [structure is given to you] to (2-carbonyl-pentyl)-cyclohexane [structure is given to you].</p>
<p>For this problem you would need the knowledge of many different reactions to get rid of the alcohol, add on to the chain, and add a ketone. It's sort of like a puzzle. What will it take to get me from here to there? Very analytical and not really the usual thought process of engineering or pre-medical students in these classes (unlike me, who just loved this crap for some reason). The different and various reactions would have already been learned (we learned over 80 I think) and committed to memory over the course of the semester. Even if you know all the correct reactions to reach the finished. It still isn't even that easy because you need to know the intermediates and the stereochemistry of each reaction (will the resulting product be Markovnikov or anti-Markovnikov) because you don't want to add the right functional group in the wrong place either. Very complex and many parts.</p>
<p>2) Draw the mechanism [transfer of electrons and bonding steps through VERY specific single- or double-winged arrows] and product of trans-2-butene [structure is given to you] when reacted with borane (BH3) & THF and then NaOH, and hydrogen peroxide, HOOH (I think those are the right reagents heh).</p>
<p>For this problem you would need to remember what that combination of reagents did and how they did it (they add an anti-Markovnikov hydroxide functional group, which is -OH, for the formation of 2-butanol) and then the stereochemistry on the product (which is cis now) needs to be considered as well. From the hard to the extremely complex where some of the reactions like borane or ozonalysis are many confusing steps and then have follow-up reagents to close of the reaction. And of course make sure you draw all of the arrows not only on the paper but to the correct places, very precise stuff here.</p>
<p>Final ones 3) Explain using molecular obital theory why multi-step substitution, SN1, goes faster on a tertiary carbon rather than a primary carbon.</p>
<p>First you would need to remember the right substitution reaction. Second, you would need to remember what a primary and tertiary carbons are and the differences. Third, you would need to think how you would use obitals to explain it. You would have to include the words hyperconjugation, stable cation, and p-orbitals (+ drawings) to explain it.</p>
<p>4) Explain using MOT whether 3-methyl-cyclopropene or 3-methyl-cyclopropane [structures are given to you] is more acidic.</p>
<p>For this problem you would need to remember the differences why something would be basic. Usually alkenes are less basic than alkenes so using approx pka probably wouldn't help. What makes an acid? Easy removal of hydrogen. If you took away the most easily removed hydrogren and left a cation which would be more unstable and/or more likely to want to keep the hydrogen. It is obviously the ene which is more unstable because in cation form it fits the definition of an anti-aromatic compound (benzene is aromatic) which are some of the most unstable compounds and are usually physically impossible to form. The other wouldn't be good either but as aromatics are some of the most stable compounds in chemistry (considering the number of double bonds and cyclic nature of these compounds in the first place) anti-aromatics are the least stable and thereby the second, cyclopropane would be more likely to lose a hydrogen making it more acidic.</p>
<p>Those are very good sample questions as to what to expect. Of course my course was accelerated and probably much harder than one you would have to take. But for all others who want to know about orgo (chems, chemEs) here's your answer. It will be all the same ideas at least even if not in depth. I'm sick of people having a week or two of orgo in high school and just saying, "It's all just memorization." which it isn't. At least in my course, it wasn't. So anyone who needs to can copy this for any other orgo forums or direct them to this one.</p>