Directive Influence of Substituents on Benzene

Activating Groups (o/p-directing):

$$\text{Strongly Activating: } -\text{O}^-, \, -\text{NR}_2, \, -\text{NH}_2, \, -\text{OH}, \, -\text{OR}$$

$$\text{Weakly Activating: } -\text{CH}_3, \, -\text{C}_2\text{H}_5, \, -\text{R} \quad (\text{via Hyperconjugation and } +I)$$

Deactivating Groups (m-directing):

$$\text{Strongly Deactivating: } -\text{NO}_2, \, -\text{CN}, \, -\text{CHO}, \, -\text{COOH}, \, -\text{COOR}, \, -\text{SO}_3\text{H}$$

Halogen Exception (o/p-directing but Deactivating):

$$\text{Halogens } (-\text{F, -Cl, -Br, -I}) \implies o/p\text{-directing due to } +M, \text{ but Deactivating due to strong } -I \text{ effect}$$