ChemNoob
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Functional Groups?
Hey everyone, Im working on a project for grade 11 chem and we were asked to find the functional groups in our molecule. Mine is Kevlar, and weve
never learned about functional groups so I have no idea what Im doing. Ive tried to research some basic ones, but Im still pretty clueless. If someone
could please tell where all the functional groups are in the picture, that would be very helpful. Thanks a lot.
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DDTea
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Welcome to sciencemadness and I hope that you are enjoying your experience with chemistry. I should tell you that people here will not spoon-feed
you an answer; what I mean is that, questions phrased along the lines of, "Solve this problem for me," will not be received very well.
Instead, we'd rather you become a self-learner and assess what you know, what you don't know, and how you plan to learn what you don't know. Part of
that last bit is knowing how to take advantage of a resource like Google. Look up "Organic Chemistry Functional Groups," and you'll find websites
that offer more information than any member here has the patience to offer.
I hope this didn't come across as sarcastic. Really, I'm trying to be helpful and give you proper pointers without directly answering the question
for you  After all, science is about problem solving!
"In the end the proud scientist or philosopher who cannot be bothered to make his thought accessible has no choice but to retire to the heights in
which dwell the Great Misunderstood and the Great Ignored, there to rail in Olympic superiority at the folly of mankind." - Reginald Kapp.
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ChemNoob
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Thanks, and yeah, I didnt want to be directly spoon-fed, but we never learned anything like this in class and looking up on google didnt find me with
too many results. Even my friend in University level Chemistry couldn't figure out all of the functional groups. After looking around, the only groups
I think may be there are amines and carbonyl, and even that Im not too sure of. Ive literally been trying to look all day, but when the project is due
today I was getting rather desperate. I know there is a group similar to benzene rings, but seeing as Kevlar only has 4 hydrogens attached, I didnt
think that would count and I couldnt find anything else on it :/
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ScienceSquirrel
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Have a look at this page and it does sort of jump out at you. 
http://en.wikipedia.org/wiki/Amide
[Edited on 24-5-2011 by ScienceSquirrel]
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ChemNoob
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Haha thanks. I knew there was an amide in there somewhere, but Im still a bit confuzzled on what the R and R1 means and covers. Does it mean just the
C atom or the whole benzene ring as well?
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Lambda-Eyde
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R usually means an arbitrary alkyl or aryl (benzene ring) group, or a hydrogen. It's used in the general formula to show how many connections the
atoms in the group make that aren't important to the functional group itself. R, R' and R'' just means that the groups aren't necessarily the same.
In layman terms R means "insert random group here".
Also, a benzene ring doesn't need to have six hydrogens to be counted as a functional group. It's still an aromatic ring.
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ChemNoob
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Oh ok thanks so much
So In the structure of the Kevlar molecule, the amide includes the whole centre part plus the two benzene rings? Or are the rings just separated as
their own functional group?
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Nicodem
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It's better called an anilide, not just an amide as that is too widely defined. Anilides are amides of aromatic amines. The difference is important in
regard to properties and synthesis.
The anilide functional group is defined as Aryl-NR<sup>1</sup>-CO-R<sup>2</sup> where aryl is a phenyl or substituted phenyl
group, and R<sup>1</sup> and R<sup>2</sup> are hydrogen, alkyl or aryl groups. These substitutions are not part of the
functional group, but they do define it, though only the N-CO fragment is the essential part of the functional group. For example, the carbamate
PhNHCOOEt also has the same N-CO fragment, but it is not an anilide because it does not fit the definition (R<sup>2</sup> is not an alkyl
or aryl group, but an alkoxy group instead). For the same reason acetamide is not a ketone (defined as
R<sup>1</sup>-CO-R<sup>2</sup> as its
R<sup>1</sup> and R<sup>2</sup> are not an alkyl or aryl groups as they should be in ketones.
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Nicodem
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Thread Moved
24-5-2011 at 07:16 |
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