From: Ravi Orugunty (rorugunty$##$oragenics.com)
Date: Tue Mar 14 2006 - 14:28:08 EST
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.
Hope this helps. Good luck
ravi
I sincerely welcome the comments and suggestions by
Yuehui and other two people. I'd like to address
Yuehui's for now as I am too busy to reply to every
one.
As I argued in two interenational sympossiums in 2005,
prediction and explanation are two different things
conceptually. Some theories do contain both of them,
but some others do not. Woodward-Hoffmann rules are a
very valuable predicting theory derived from a pattern
of mathematical operations. It is my strong opinion
that W-H rules are not equivalent to an explanation as
neither is FMO theory. Dewar called the W-H to have
"hypnotic effect", which I could not agree more. The
reality is that no one understands how "they explain".
The discussions via revolutionary internet
communications in CCL have led more and more
scientists to accept that "orbitals are a means to an
end", which I learned initially from Prof. Richard
Bader at McMaster University. How do you understand an
explanation that is based on something of no
understandable physical meaning?
I had tortured myself over and over again for years
before I convinced myself that I have made "a
breakthrough in mechanism of concerted
cycloadditions". Now I have the confidence to defend
such a statement. If you don't agree, I'd like to ask
you to calm down and to address the following
questions in concise languages without metaphors:
1. What is mechanism of chemical reactions?
2. Are mechanisms of chemical reactions important in
chemistry.
3. Was the mechanism of concerted cycloadditions well
established before at the theoretical level?
4. 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!)
My theory is about how electrons to move in a
concerted reaction. I don't agree with Yuehui that a
theory must be able to predict. "The earth revolves
around the sun" is a theory on paper but a fact in the
nature.
I could not publish my papers, and I don't need one. I
don't make a living from publications (as advised by
Einstein? -:). But the knowledge if correct will
benefit the human society one way or the other.
Thanks.
Sengen
--- Yuehui Zhou <yuehuizhou$##$hotmail.com> wrote:
---------------------------------
Another critieron for a theory is predicting the
outsome of the related reactions. You can do some
reactions based on your theory to test it and publish
the results. Without predictting power a theory is
just a theory on paper.
Also don't try to make your result a big deal. You may
think it is, but it's not the way to persuade
others. Try the online journals, Molecules, for
example. The editor is a Chinese fellow. Good lucky
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Message: 3
Date: Tue, 14 Mar 2006 03:46:53 +0000 (GMT)
From: Mugunthan G <mugunthan_gee$##$yahoo.co.in>
Subject: ORGLIST: Acetylation with Iodine
To: everybody$##$orglist.net
Message-ID: <20060314034653.97520.qmail$##$web8509.mail.in.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"
Hi Nalini,
acetylation goes well pyridine, but why to use bad
smelling and toxic stuff pyridine. you can very well to this with acetic
anhydride and iodine, which will be easy for workup and purification.
with regards
mugunthan
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Message: 4
Date: Mon, 13 Mar 2006 18:40:14 -0800 (PST)
From: Krupa Shukla <krupa_shukla$##$yahoo.com>
Subject: ORGLIST: SOP
To: everybody$##$orglist.net
Message-ID: <20060314024014.58969.qmail$##$web50503.mail.yahoo.com>
Content-Type: text/plain; charset="iso-8859-1"
Hello everyone
I have been assigned to write SOP (Standard Operating Procedure) for
large scale reductions. (SOPs point out the hazards associated with a
particular operation) It would be very helpful if someone can provide a
university link (if any) or have an idea how to deal with large scale
reductions, just briefly. Besides metal hydrides as reducing agents, what
other reducing agents have safety concern? It would be great if someone can
list reducing agents. my task would be much easier then.
Thanks for the help
krupa
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Message: 5
Date: Tue, 14 Mar 2006 06:42:12 +0100
From: Barry Hardy <barry.hardy$##$tiscalinet.ch>
Subject: ORGLIST: Advanced Training Workshop Week at Oxford; Early
Registration
To: everybody$##$orglist.net
Message-ID: <5.0.2.1.0.20060314064117.0208dde0$##$mail.tiscalinet.ch>
Content-Type: text/plain; charset="us-ascii"
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best regards
Barry Hardy
eCheminfo Community of Practice Manager
Tel: +41 61 851 0170
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