From: Sengen Sun (sengensun$##$yahoo.com)
Date: Wed Jul 16 2003 - 23:35:05 EDT
For the concerted Diels-Alder reaction between
ethylene and 1,3-butadiene, there two possible
mechanisms: 1. Concerted electron-donating and
accepting in a closed-shell process at the two bonding
locations; 2. Concerted spin coupling at the two
bonding locations.
My choice is 1. The reason is simple - the
electrostatic forces push electrons to flow around.
Recently, there have been some published theoretical
studies to claim 2. When I read those publications, I
found that the computational techniques used cannot
reflect un-equilibrated physical reality. These claims
are therefore invalid to me. I discussed the
mechanistic issues in the Preprint Server:
http://preprint.chemweb.com/orgchem/0201002 Playing
the Natural Puzzles of Concerted Cycloadditions: What
Are the Tricks behind the Scene?
http://preprint.chemweb.com/orgchem/0107002
Collision-induced electron reorganization as the
general mechanism of concerted cycloaddition
reactions.
http://preprint.chemweb.com/orgchem/0210002, Natural
forces as the foundation of theoretical explanations
in organic chemistry.
http://www.ccl.net/cgi-bin/ccl/message.cgi?2003+06+02+016
Do Molecular Orbitals Explain Chemistry?
If any body wishes to read my preprints, I would be
very happy to forward the pdf files to you. Just send
me a personal E-mail to sengensun$##$yahoo.com. The
Preprint Server is free to view or post articles as
soon as you establish you user name and password.
I would like to ask people in this list to help me in
understanding the mechanistic issue. What is your
choice for the two possible mechanisms 1 and 2. And I
am interested in some explanations in the language of
organic chemistry about your choice.
Cheers!
Sengen
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