From: Sengen Sun (sengensun$##$yahoo.com)
Date: Wed Mar 15 2006 - 19:23:45 EST
Ravi,
I did not say you atacked me. Actually we have been
engaging in a very friendly discussion.
Maybe I am a little offensive. But I would say that
like many other organic chemists, Ravi was in a deep
sleep with spiritual comfort under the influence of
the hypnotic effect of W-H rules in his first post.
But Ravi is close to being fullly awakened in the
second post -:).
Metaphors are sometimes good and interesting. But as I
remember, Hoffmann once wrote in a journal an article
(or maybe a poem) with EXCUSIVELY metaphors except the
title on Theoretical Chemistry. If any one is
interested in that, I can try to find it and send it
to you upon request by e-mail.
A clear language from Hoffmann is actually needed that
W-H rules are just a pattern of mathematical
operations for prediction but not mechanism or
explanation. Otherwise, the majority of organic
chemists would remain in sound sleep with spiritual
comfort -:)
Regards to all,
Sengen
--- Ravi Orugunty <rorugunty$##$oragenics.com> wrote:
>
>
> -----Original Message-----
> From: everybody-bounces$##$orglist.net
> [mailto:everybody-bounces$##$orglist.net]On Behalf Of
> everybody-request$##$orglist.net
> Sent: Wednesday, March 15, 2006 12:52 PM
> To: everybody$##$orglist.net
> Subject: Everybody Digest, Vol 19, Issue 13
> Hi Sengen Sun,
> I wasnt attacking you personally. I read your
> article and i agree with you
> in many instances.
> My point is as follows " Mechanisms and the Art of
> writing reasonable
> mechanisms " is nothing more than a language. How
> one chooses to use it
> gives one either meaningful information or nothing
> at all.
> The same is also true for W-H rules and all other
> rules. They should be
> taken as rough guides and no more. As I already
> mentioned I'm an
> experimentalist and for me the proof is always in
> the pudding. Run the
> reaction and see what happens, leave the predictions
> to the theorists and
> yes i dont trust most of the calculations :)
> i havent read the paper by Hoffman that you cite but
> i certainly shall.
> I also agree with you that not everybody has read
> the actual monograph by
> woodward and hoffman. I actually got a copy by
> chance from a retired
> faculty and am reading it even as we speak.
> Good luck
> regards
> ravi
>
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> Today's Topics:
>
> 1. A breakthrough in mechanism of concerted
> (Ravi Orugunty)
> 2. Re: A breakthrough in mechanism of concerted
> (Sengen Sun)
> 3. Chemistry Deparment Shutting (Nigel R
> Treweeke)
>
>
>
----------------------------------------------------------------------
>
> Message: 1
> Date: Tue, 14 Mar 2006 14:28:08 -0500
> From: "Ravi Orugunty" <rorugunty$##$oragenics.com>
> Subject: ORGLIST: A breakthrough in mechanism of
> concerted
> To: <everybody$##$orglist.net>
> Message-ID:
>
<FAEGJIOFKPDFCBEHEACGMEGNCCAA.rorugunty$##$oragenics.com>
> Content-Type: text/plain; charset="US-ASCII"
>
> Dear Sengen,
> I have missed out on the earlier part of your
> messages wrt to a breakthrough
> in mechanism of concerted reactions. However i will
> try to answer the
> questions that you have raised without resorting to
> any metaphors.
> Hopefully this might help.
> Q) What is the mechanism of a chemical reaction?
> A) Any idea/theory that sufficiently explains the
> bonds that are broken and
> formed during the course of any chemical process is
> a mechanism of that
> chemical reaction.
> Mankind likes to organize its ideas so that it can
> understand nature and
> therby harness it to some useful work and this is
> also true for mechanisms
> in chemistry. Granted that we really dont need to
> know the mechanism in
> sufficient detail to get a reaction to work . Two
> examples will be provided
> to sufficiently buttress the above statement.
> Undergraduates in chemistry
> for the most part when they start their first lab
> rarely know the mechanism
> of a Grignard reaction but are able to perform the
> reactions in a lab (Good
> supervision is essential though). Prehistoric man
> had no idea about the
> mechanism of reductions and electron transfer and
> yet was highly successful
> in smelting and purifying iron and other metals.
> It is perhaps from those early discoveries, that
> lead man to further
> investigate and understand nature. More so
> understand nature in terms that
> would make sense of a myriad of processess that were
> observed in daily life.
> It is from these observations the language of
> chemistry evolved and is
> taught as mechanism and theory of chemistry in any
> modern class.
> In that respect i do agree with you that mechanisms
> and theories are no more
> than a language used by chemists to communicate
> their ideas.
>
> Q)Are mechanisms of chemical reactions important in
> chemistry.
> A) Yes, mechanisms are important not to perform
> chemical reactions (see the
> example of prehistoric man) but are extremely
> neccessary to understand
> chemical processess. Once one has a better
> undertanding of any process one
> can develop newer reactions and thereby new products
> etc. Therefore the
> language of mechanisms has its utility.
>
> Q) Was the mechanism of concerted cycloadditions
> well
> established before at the theoretical level?
> A) We havent established a chronological time here
> but i will answer it
> without any metaphors. When Diels and Alder
> published their first papers
> (around 1910 or so). The mechanism of concerted
> reaction was not known. In
> fact, the electronic theory of chemical bonds was
> being developed by G.N.
> Lewis and others( i hope my memory serves me right
> here so please correct me
> if i'm mistaken). However as our knowledge of
> matter progressed with time,
> Woodward-Hoffman and Fukui developed the modern
> rules for cycloadditions and
> they seem to have served mankind in particular
> organic chemists pretty well.
> Have these rules stood the test of time? Yes. Any
> process that violates the
> W-H theory can be explained using an alternate
> mechanism that would not
> require the use of the conservation of molecular
> orbitals. The "hypnotic
> effect" of W-H rules are in their elegance in
> predicting the feasability of
> a thermaly catalyzed cycloaddition reaction based on
> orbital overlap.
> Q)Do my computational data tell us some new
> knowledge
> of electronic reorganization - the mechanism?
> (Please,
> do not tell me to use your favored computational
> approach unless you can use your approach to prove I
> am wrong!)
> A) Cant reply to this question? I'm not a great
> believer of doing
> extraordinary computation as i consider myself to be
> an experimentalist.
> For me the proof is invariably in the pudding ( a
> metaphor for a change )
> this is particularly true when one is dealing with
> peptides and complesx
> biological systems.
>
> If you have a new theory share it with your fellow
> scientists by all means.
>
> Facts are observed truths for example matter,
> energy, gravity and everything
> else under the sun that nature presents before us.
> Theories are explainations given by mankind.
> Gravity existed long before
> Newton explained it and the same is true for
> cycloadditions. So take it
> easy.
> As to wether you choose to publish or not is
> entirely your choice. However,
> I would encourage you to put forth your ideas before
> your peers and learn
> from what they have to say and make professor Bader
> proud.
>
=== message truncated ===
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