CCL: Enantiomeric excess via Conformational analysis

I’m sorry, but if you get unequal energies for enantiomers, this just means your conformational search routine is wrong/incomplete. We actually use this to test our conformational search setup. To get enantiomeric excess if a reaction, you MUST do conformational search for the TS, not easy! We have a method for it, but it’s not black box, requires much work, and understanding the fundamentals: 


Sent from my iPhone

On 10 Dec 2017, at 06:06, Mohamed E. A. Safy m.safy*o* <owner-chemistry-: at> wrote:

Sent to CCL by: "Mohamed E. A. Safy" [m.safy{=}]
Dear CCL community
In one of our running projects, we are working in a collaboration with
organic chemists. They asked us to perform calculations on enantiomeric
excess of a molecule.
According to the transition state theory, the calculations should be run on
the transition states to predict the enantiomeric excess. This is because
the R- and S- enantiomers are equal in energy.
Indeed, if we searched for the most stable conformation for each of R- and
S-enantiomers using conformational analysis technique, we will find that
the most stable conformation of R- and S- enantiomers are not identical in
energy. Moreover, if we used the most stable energy in Boltzmann
population, we will get %population in agreement with %ee (enantiomer
So, we were wondering if this approach of conformational analysis followed
by Boltzmann calculation would be a good approach to predict the %ee? If
yes, so is there any reference would support our approach?
Any comment would be highly appreciated.
Have a nice day
M. Safy

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