problems with energyE() calculations

User 870ab5b546

10-10-2014 19:31:56

We're having some doubts about the accuracy of the energyE() (π nucleophilicity) calculations that we use to predict the results of electrophilic aromatic substitution reactions. Sepcifically, we think that the values for toluene are inaccurate. Can you tell us the source of the HMO parameters that you use for these calculations, especially the ones you use for the CH3 group?

User 25d107bd42

14-10-2014 06:40:02

It would be nice to compare the HMO parameters f.e. between the
pi-donor substituents -NR2 -OR -Cl -Br -J and the hyperconjugated
-CH3 group. All these should give a lower energyE(+) for para
and ortho positions. But -CH3 gives for para an E(+) 2.5354
being nearly the same as for the unsubstituted benzene 2.5359.
The values should show more difference.

Is there a documentation of these HMO-parameters? We only found the
hint look in Streitwieser's book.

Hans-Ulrich and Julia

ChemAxon d51151248d

15-10-2014 13:38:12


the parameters can be found in Neil Isaacs's book Physical Organic Chemistry. The reference can also be found in our documentation:

Best regards,