From: Sengen Sun (sengensun$##$yahoo.com)
Date: Tue Mar 14 2006 - 20:07:12 EST
Dear Ravi,
I sincerely welcome your comments. But the issues you
and I raised here really deserve a public debate in
the ORGLIST. I welcome every one to participate. In my
opinion, the issues here are entirely the confusion we
have had for the last half century. I'd like to start
with some remarks I made in CCL in 2003.
http://www.ccl.net/cgi-bin/ccl/message-new?2003+06+02+016
"...Fukui & Hoffmann well deserved 1981 Nobel
prize due to their discovery of the correlation
between MOs and chemical reactivity. But I don t think
that everything they said is correct. We must
criticize their mistakes hard without mercy. Their
mistakes could have too much negative impacts on our
scientific community due to their high profiles,
especially on experimental chemists with little
theoretical knowledge."
I feel it is much easier to convince many theoretical
chemists than experimentalists that W-H rules are no
more than a very useful mathematical tool for
predicition of reaction products. Hoffmann once asked
a very funny question something like "Should
experimental chemists TRUST theoreticians?" (not the
exact words, but see Theochem 1998, 424:1-6)
I do not have a beter way to explain, but let me give
you recent one of particular examples of conceptual
confusion made by Hoffmann (See JACS, 2002, 124, 6836,
Scheme 1, I will forward this article to any one if
requested by e-mail). There, the intramolecular proton
transfer was mistakenly treated as hydride transfer.
That is, the arrows should be drawn in the exactly
opposite direction. I would be bad if I were just
exaggerating some accidental errors. This is not an
accidental error. Such a mistake derived from our
mental assumption of orbital control, so that
well-established acid-base theory in chemistry can be
overturned but by a high profile Nobel Laureate! To
me, his philosophy is that arrows can be arbitrarily
drawn due to orbital control!
I do not mind if you call me an attacker. But I have a
high expectation to a Nobel Laureate. Such a kind of
conceptual mistakes in JACS are unacceptable and
should be corrected by the authors!
For more, please see my ppt file:
http://www.ccl.net/cca/documents/ConcertedCycloadditons_2/
By the way, I am proud of myself, while Bader would be
proud of nothing about me as asserted by Ravi. I am
sure that Bader does not know who I am although I did
my Ph.D. at McMaster in organic chemistry (1989-1994).
But I have known him for 20+ years and have admired
his philosophy of QM ever since.
Regards,
Sengen
--- Ravi Orugunty <rorugunty$##$oragenics.com> wrote:
> 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
>
>
>
=== message truncated ===
__________________________________________________
Do You Yahoo!?
Tired of spam? Yahoo! Mail has the best spam protection around
http://mail.yahoo.com
_______________________________________________
ORGLIST - Organic Chemistry Mailing List
Website / Archive / FAQ: http://www.orglist.net
To post a message (TO EVERYBODY) send to everybody$##$orglist.net
To unsubscribe, send to everybody-request$##$orglist.net the message: unsubscribe your_orglist_password your_address
This archive was generated by hypermail 2.1.4 : Tue Feb 13 2007 - 14:17:01 EST