Last organic 1 test before final...DONE!

[dexadental]

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Oh my god guys, I don't know about you all, but I can't ever sleep before my organic chemistry tests. We just took our last one and I think I did great! It was on Chapter 8/9 of the Wade Organic Chemistry book. Lots of reagents and reactions to remember, but I got through it! Sorry guys, but I'm extremley exhausted and thrilled at the same time, I just had to post! Good luck to everyone in their academic endeavors...and I know all of you who have applied somewhere will go somewhere in the future.

 

[trypmo]

Congrats! 😀

 

[smuwillobrien]

It's good to hear that things are going so well for you, dexadental. I thought general chemistry was fairly easy (I got an A+ in both semesters), but I'm finding that organic chemistry is ever easier. There are no numbers to crunch, there are no equations to memorize (at least not yet), and everything else is pretty intuitive once you've learned some pretty simple concepts. We're through with the midterm for this semester (Got a 97%!), and the final is coming up on December 16th.

Hope all goes well with you, and I hope you ace the final! 🙂 😉

 

[Biogirl361]

i hear you man, i am speaking to you right now on 2 hours of sleep last night before today's biochem exam (last one before finals.) that's right stayed up until 3 studying and then just layed there until 5 or 6 completely incapable of going to sleep and feeling like i was about to have a heart attack. but i think i did really good, it was much easier than it probably could have been. 😀

 

[Tzips]

I think i'm getting an inferiority complex 😀 ... i loved the concepts but could not memorize the 50+ reactions of carbohydrates alone, so never got a "97%" on an orgo test. i'd just lie in bed with visions of long carbon chains dancing through my head, slowly going insane.... fun, though 😉

but congrats guys, and keep up the excellent work!!

 

[blankguy]

Am I the only who finds orgo to be a tough going. I am still on track to getting a good grade but man is it rough. The sn1, sn2, E1 and E2 is a bit confusing. Subtrate, Nucleophile/Bases, leaving groups and solvents. Maybe it is the way that is being presented in my class. 😕

 

[dexadental]

In response to my comment, I think part of the reason why i'm doing well in orgo (A)...no A+ at UF, is that I rewrote the whole freaking book! hehe. Hey! Anything to get me that A right?

 

[blankguy]

The are a few number of reaction mechanisms in orgo: they're either substitution, addition, or elimination. You gotta put in your dues and master the guidelines for what constitutes sn1/E1 and sn2/E2... VSEPR (primary, secondary, etc) and solvent (polar protic vs polar aprotic), there's no easy way around it, you have to read the material and understand it; the best part is that the material is easy, just a little intimidating at first. Once you're over this hump, then it's strictly memorization... there will be no more concepts to learn after you begin to work with alkenes... you will memorize ALOT of material for a very long time to come. Be prepared and enjoy this portion of orgo, it's the best (it was fun for me) and will ensure you success by contributing to your personal confidence and why the many reactions you memorize occur. For instance, the role of the carbocation will become increasingly prevalent and you'll be better off learning Sn1/E1 now, as opposed to when you have 100+ reactions to know for a midterm. Also, learn it now for the DAT, if you master this stuff you'll definately get a 25/26 on orgo. Take really good notes from the book and in class and good luck.

So far I got this for preferred for each mechanism

Substrate: Sn1=3rd degree alkyl halide Sn2=1st or methyl E1=3rd degree E2=can work with any alkyl halide

Nucleophile: Sn1=weak(because the leaving group leaves first) Sn2=strong(it is forcing itself on the substrate so that it can jettison the leaving group)

Bases: E1=weak base (most cases parallels the nucleophilicity) E2=strong base(3rd degree hindered base included)

Leaving group: Sn1=good(it leaves first) sn2=weak(it is forced out)
E1=good E2=weak

Solvent: Sn1 and E1 protic Sn2 and E2 aprotic.

So if the nucleophile ends up acting like a base there is a good chance that it may end up with an elimination??

 

[blankguy]

Exactly, a strong base will favor the elimination product

That's the problem that I'm having. How do I know when it is a base and when it is going to act as a nucleophile? Take for example the case of NaOCH3. That's a base right?? A strong base? As Opposed to CH3OH?

I think I'm going to have to constantly review this stuff just to make up for it in the next test and final.

Just to reiterate what I said about Subtrate in Elimination. Sterics is a nonissye. It is more an issue of how many sites can be deprotonated. In a strong base it doesn't matter it is strong so it can deprotonate from 1st degree through 3rd degree. Whereas the weak base it is so it will work best with 3rd degree more sites to deprotonate.

 

[dexadental]

In the case of a strong base/strong nucleophile, you usually look at the substrate for clues as to if it will go Sn2 or E2. If heat is involved, it almost always goes elimination, and also if its third degree (the halogen on the substrate). Its detailed I admit, but doing problems will greatly help you. That is ultimately how anyone gets the hang of organic.