View source for Talk:Mod5:mathieu.fox08

Cp: Energies are fine for 1 and 2 (too many dec. places though!)   You are right that the endo-isomer is kinetically preferred, but wrong about the reason.  The endo-isomer suffers more from sterics than the exo one (as in the products) - so we need another explanation as to why it is preferred (usually, stabilising "secondary orbital interactions" present in the endo-TS but not the exo-TS are invoked).  3 and 4 energies good.

NAD: Like the idea of systematically testing different starting points.  Are the angles quoted for the minimised structures, or for the starting structures?  What forcefield was used?  It's a pity you haven't given your structures for me to look at.

Taxol: Your structure 10 is actually the "up" isomer.  Your 9 has the wrong alkene geometry unfortunately; also the 6-ring is in a boat conformation.

CCl2: Orbitals and stretches look OK.   Did you look at the bond lengths?  Note that the OH-substitued alkene is definitely electron rich (remember, it's an enol!)

Mini-project: Nice example! Note that your calculation to convert a ratio of 7:1 into an energy value gives you the DIFFERENCE in energy between the two TSs, not the "total change in Gibbs free energy" (also you are out by a factor of 1000 - it should be 4.8kJ/mol).  Nice TS analysis! :)  Your calcs look good - did you think about which particular carbons show a big discrepancy, and why?