In an Organic Chemistry II class you often add groups to aromatic systems. If you’re wondering where the substitution will take place, check out this table for some guidelines. When using this table, remember two things:

  • O-p-directors always beat m-directors.

  • Strong activators always beat weak activators.

Classification of Various Aromatic Substituents
Very Strong Activators -NH2, -NHR, -NR2, -OH, -O
Moderate Activators -OR, -NH-CO-R, -O-CO-R
Weak Activators -R, -C6H5
Mild Deactivators -F, -Cl, -Br, -I
Very Strong Deactivators -N+R3, -NO2, -CN, -CCl3, -CF3
Moderate to Mild Deactivators -CN, -SO3H, -CO-R, -COOH, -COOR, -CONH2, -N+H3