CCL:G: Enantiomeric excess via Conformational analysis



Hello Mohamed,
 Hope you all the success in your work. In my opinion, the energy obtained from
 conformationl analysis is not as accurate as that obtained from quantum
 mechanical calculations because it depends on molecular mechanics. Gaussian 09
 or similar softwares can predict the energy of your molecules with high
 accuracy. Accordingly, I recommend using the transition state (ts) calculations.
 Another idea is to use the three methods (ts, conformational analysis and
 Boltzmann population) and see if they end up with the same results.
 Regards,Ahmed
 Sent from Yahoo Mail on Android
   On Sun, Dec 10, 2017 at 7:02 AM, Mohamed E. A. Safy
 m.safy*o*compchem.net<owner-chemistry**ccl.net> wrote:
 Sent to CCL by: "Mohamed E. A. Safy" [m.safy{=}compchem.net]
 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
 excess).
 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
 -= This is automatically added to each message by the mailing script =- 
         Subscribe/Unsubscribe:
      Job: http://www.ccl.net/jobs