Page 1 of 1

placement of the dipole (#4.28)

Posted: Wed Mar 08, 2017 5:39 pm
by Kim
in #28 in Chapter 4 of the organic textbook, you have to write the mechanism and the transition state
I understood it except this part:
Image
why is the positive dipole on the middle carbon as opposed to the carbon forming the bond with the H?

Re: placement of the dipole (#4.28)

Posted: Wed Mar 08, 2017 6:41 pm
by Chem_Mod
Think about the structures before and after the first transition state.

Before the transition state, both HBr and CH3CHCH2 are neutral. After the transition state, Br- has a negative charge and CH3C+CH3 has a positive charge on the central carbon.

The transition state should be between these two states, and so the Br should have a partial negative charge in the TS and the central carbon should have a partial positive in the TS.