For a π bond, p orbitals should be________
when they overlap. As a result, in the E2 mechanism, an _______
elimination is said to occur.
I tried "p orbitals should be parallel when they overlap. As a result, in the E2 mechanism, an antiparallel elimination is said to occur."
Looks good Rob!
Close, but not quite. For a π bond, p orbitals should be perpendicular when they overlap, not parallel. This is because the electron density in a π bond is primarily concentrated above and below the plane of the bonded atoms, so the p orbitals must be able to interact side by side in a perpendicular manner.
Regarding the E2 mechanism, you're on the right track. However, it's not an antiparallel elimination but a concerted elimination. In the E2 mechanism, a strong base abstracts a proton adjacent to a leaving group, resulting in the formation of a π bond and the expulsion of the leaving group. This process occurs in a single step, with the base and the leaving group leaving simultaneously. The term "concerted" refers to the fact that both events happen at the same time.