Hey guys, I have a stupid question to ask, but I just want to make sure I am right. A carboxyl group on a benzene ring is deactivating because of the partial + charge on the carbon as a result of being bonded to oxygen, right?
Yes- the polar C-O bond can withdraw electron density (inductive effect). Also, electrons can resonate up into the carboxyl group which removes electron density as well. The inductive and resonance effects reinforce each other... this deactivates the ring.