Re: ORGLIST: Functional Groups

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From: tubert$##$eros.pquim.unam.mx
Date: Mon Apr 09 2001 - 14:31:18 EDT


I think that the definition of functional groups is practical and somewhat
informal, so it is impossible to calculate all possible functional groups.
When I was writing a synthesis computer program to recognize FGs in molecules
I found that as soon as you have to define the FG formally, a lot of questions
arise.

For example, take an alcohol, typically represented by ROH. What is the "R"?
If you say "anything" you run into trouble, as the R might turn the OH into
part of a greater group. Aside from obvious possibilities like having an acid
RCOOH instead of an alcohol, what if you have RCH(OH)2? Would you consider
this as two alcohols or a aldehyde hydrate? Or RCH(OH)CH2OH? Two alcohols or a
1,2-diol? RCH=CHOH; is it an alcohol and an olefin or is it an enol?

Functional groups may be defined as substructures that give a molecule
specific chemical properties. When two basic functional groups are close to
each other, that may or may not give the molecule a completely different
reactivity. For example, a 1,1-diol is very different from two independent
alcohols, but a 1,1-dihalide is not that different from two independent
halides (but it has its differences anyway). So, whether to consider them as
new functional groups or not is a matter of taste; of what are the particular
interests of the chemist in that moment, etc. Maybe sometimes you find it
convenient to consider a 1,2-diol as a functional group, and sometimes you
consider it as just two plain old alcohols, which happen to be neighbors.

Regards,
   Ivan

Ashutosh <ashujo$##$yahoo.com> said:

>
>
> This might seem ridiculous but I was just thinking as follows;
> We now know hundreds of functional groups. But could there be more
functional groups?
> We could call the organometallics as functional groups.
> What about new functional groups?
> I could just take up some 4-5 atoms and bonds, try all permutations and
combinations of them and have some 20 new functional groups.
> However many functional groups would be unstable or more importantly,
useless.
> A functional group would be useful, if it appears in nature to some extent
and it is synthetically useful.
> Could we have a 'FGP' or Functional Group Project, in which all natural
resources are exhaustively studied, then considered by physical and
theoretical as well as computational chemists regarding their reactivities and
then synthetically modified to create useful products, or even biological
analogues.
> Of course, this would be an international endevour. But the cost and time
spent could be worth while.
> This is just a thought (not some project that i am suggesting!) that I had
and I was wondering if anyone has any opinions or ideas related to this.
> Thanks
>
> Ashutosh Jogalekar
> University of Pune
> India
>



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