ECHET96 Article 083:

sglover (
Fri, 12 Jul 1996 16:08:53 +2308


Two things about your excellent poster. Firstly, is the energy
diffence between ground states of the bridgehead N-oxides 6 cal/mol or
6 kcal/mol. I any case the ability of STO-3G calculations to describe
such a system is probably limited. A higher level of calculation is
called for and particularly so if you are going to look at the
transition states which would be biradicaloid in nature. Secondly, is
the first step of the Meisenheimer rearrangement really reversible.
If so then that would imply that the difference in rates lies in the
position of the respective equilibria. Since there is probably little
barrier to rotation about the C-N bond in the ruptured biradical
form, the same equilibrium ought to be obtained from either isomer and
hence the same overall rate of conversion. You could test this by
isolating unreacted material from either pure isomer and determining
if it had isomerised to a mixture. I wonder whether in this case the
first step is simply irreversible and you are just looking at a
kinetic effect.
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