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Offline robocop12

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General mechanism questions
« on: October 19, 2012, 12:06:39 AM »
Hi all! Hope you can offer some advice. Got some questions.

I received a 70 on my last test, that was going over basic organic chemistry stuff like Sn1/2, IUPAC naming, functional groups, etc. The major offender was the parts that dealt with mechanisms, especially the drawing. Its weird as I can predict products fine if you give me some reactants and solvents (atleast on the test I did it perfectly..) but when it came to drawing I just messed up badly. Since then I took it to myself to study much much harder. I talked to my professor and he said for mechanisms its easy as you can just make up problems and do it.

Heres where I need your folks help and advice. I cannot for the life of me make up reactants and do mechanisms so Im taking it to the internet to see what you guys can tell me. I just dont want to be wrong....like going on to Sn1 say I have a tertiary alcohol and want to make an alkyl halide, I might forget there is rearrangements and get the answer wrong. Id like to kind of have a "solution" to my mechanisms.

Do you know any websites that helped you get through organic chem, primarily for mechanisms? I realllllly want to get an A, now I have a C, and I just want to soak up and absorb any advice you throw at me. Thanks!

Offline Dan

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Re: General mechanism questions
« Reply #1 on: October 19, 2012, 03:21:42 AM »
I would recommend some books:

Reaction mechanisms at a glance - Mark Moloney Link

The art of writing reasonable organic reaction mechanisms - Robert Grossman Link
My research: Google Scholar and Researchgate

Offline robocop12

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Re: General mechanism questions
« Reply #2 on: October 19, 2012, 10:22:07 AM »
At the moment I dont have money to spend on those books :/ Would you recommend anything else thats available on the internet, hopefully for free? D:

Offline willug

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Re: General mechanism questions
« Reply #3 on: October 19, 2012, 12:38:30 PM »
Probably not supposed to say this, but... if you have look on google you can probably Robert Grossman's book (I did). It is really quite good... especially the section on organometallic chemistry.

Offline Dan

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Re: General mechanism questions
« Reply #4 on: October 19, 2012, 03:14:03 PM »
At the moment I dont have money to spend on those books :/

Library.
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Offline orgopete

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Re: General mechanism questions
« Reply #5 on: October 19, 2012, 09:04:45 PM »
I am surprised that your textbook does not have sufficient problems to practice upon. I too find it weird that you could successfully predict the products of reactions, but if asked how they should form, you are confused. A mechanism is simply a rationalization of the electron movements leading to the product. I have always encouraged (demanded would be more correct) students to learn the mechanisms. If you know the mechanism, then you might rationalize what product may form, even if you have new reagents.

I discovered students were generally more successful in writing a mechanism if they knew what the product was than if they had to write a mechanism to predict the product. That is, if you know a mechanism, you can use it to predict the product. If you are learning a mechanism, then not knowing the product may allow you to make an error in writing the mechanism. If that is so, then the mechanisms of any problems can be written out. If you know the products, then you should be able to be successful in writing the mechanism.

If you are really confused about mechanisms, then go to http://www.curvedarrowpress.com/agocm/inside/sampler/sampler.html
If you print out Part A, I guarantee you can do them. Then print out Part B, you should be able to do them as well. They are the same problems repeated. If you could do Part A, then you should be able to do Part B. Then do Part C. These are the same problems repeated again, but they are written similar to the problems in a textbook. Part D contains the completed problems.
Author of a multi-tiered example based workbook for learning organic chemistry mechanisms.

Offline robocop12

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Re: General mechanism questions
« Reply #6 on: October 20, 2012, 01:41:21 AM »
Thanks for that website. I noticed some I can do and some I cannot. I am JUST learning about R,S and stereochemistry in general...havent worked with many functional groups, just halogens, alkenes, alkanes, alcohols. Elimination, addition, and substitution. Some of those seemed a bit too complicated.

Are you familiar with Carey and Giuliano's Organic Chemistry (8th edition) book? Thats what Im using. Maybe my fault is that I am not reading the book (to be honest I didnt really touch the book in my general chemistry classes and passed with flying colors after taking AP Chem).

I know a lot of homework my teacher assigns is more on the concepts and less on the mechanisms which I find I need help with the exact opposite. I can get every other concepts save those which deal with mechanisms. Newman and Fisher projections? Sure, relatively straight forward. IUPAC naming is easy, for the most part. Those really are the only concepts that we have learned (obviously the big pictures...theres tons of stuff Im sure Im not recalling.) This is an Introductory Organic (Organic I maybe?) so right now I just need to learn the basics.

Im just...not getting it. I dont know why Ethanol works with so and so for eliminations and why t-butanol works with so and so for E reactions too! Its weird as Im the student that always asks and tries to answer questions in class, but when it comes to mechanisms I might as well have a brain fart.


Offline Dan

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Re: General mechanism questions
« Reply #7 on: October 20, 2012, 11:43:10 AM »
Im just...not getting it.

That's because you haven't got a proper instructional text on mechanism. I have not seen any free resources that are good enough. Three texts have already been suggested in this thread that teach you mechanism logically from the basics upwards.

Just go to the library if you don't want to buy them.
My research: Google Scholar and Researchgate

Offline robocop12

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Re: General mechanism questions
« Reply #8 on: October 20, 2012, 10:40:32 PM »
Im just...not getting it.

That's because you haven't got a proper instructional text on mechanism. I have not seen any free resources that are good enough. Three texts have already been suggested in this thread that teach you mechanism logically from the basics upwards.

Just go to the library if you don't want to buy them.

Hey Dan, Im sorry for sounding super difficult and stubborn. I dont mean to come across that way. I doubt my community college has those texts. I really just want to learn from what I have; some "Access" worksheets, a book, and a bunch of lecture notes. Other people are getting by just fine...just not me...


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