Deactivating group aromatic explanation

The substituent in this case (Cl) is an ortho-para director for the same reason that an OH group is an ortho-para director (the explanation for this directing effect can be found in your textbook). But, unlike OH (which is an activator). Cl is a deactivator. To explain why, we must explore the effect of a halogen (such as Cl) on the electron density of the aromatic ring. As we have seen in the previous section, our analysis must focus on two factors induction and resonance. Let s start with induction. Just like an OH group, a halogen is also electron-withdrawing by induction ... 

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