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Partial Charge

Posted: Fri Mar 17, 2017 10:42 pm
by Michael_Johanis_2K
On the final, if we need to draw a mechanism with the transition step(s), do I have to put the electronegativity of each atom?

For example, in electrophilic addition, propene + HBr ---> 2-bromopropane. For the first step, do I need to put partial positive next to H, and partial negative next to Br? For Transition State #1, do I need to put a partial positive at Carbon and a partial negative at Bromine?

Re: Partial Charge  [ENDORSED]

Posted: Fri Mar 17, 2017 11:55 pm
by Chem_Mod
Partial charges in TS do not have to be indicated.

The charges on intermediates, for example carbocations and halides such as Cl-, do need to be included.

One needs to know conceptually the partial charges in order to get the mechanism right, but drawing-in the partial charges on TS structures is not required. I did it in class to help you understand which was the nucleophile and which was the electrophile.

Folks, my review was 2 hours today ending at 6pm with serious overtime, and I've done several hours of admin email after my Friday review. It is now midnight Friday and time to sign-off.