Question

Substituents on an aromatic ring can have several effects on electrophilic aromatic substitution reactions. Substituents can activate or deactivate the ring to substitution, donate or withdraw electrons inductively donate or withdraw electrons through resonance, and direct substitution either to the ortho/para or to the meta positions. From the following lists, select the substituents that have the indicated property. The substituents are written as -XY, where X is the atom directly bound to the aromatic ring Activation of the ring towards substitution. Withdrawal of electrons through resonance. Ortho/para-directed substitution. -COOH OCH3 -SO3H -NH2 CH3 CN -NO2 -CF3 OCOCH3 NH2 COOH Cl

Answer 1

Activatienp &ing towards :-NH2 -OCH3 . Substi tutien wühdrawal d elechons thia Yesomamce Oxtho-Pana dryected substitutien : -NH2,-cl)-OCO CH3

explanation

Type 1- All groups having a lone pair at the key atom are ortho, para-directing groups. For example, -X, -O-, -OH, -OR, -OCO-R, -NH2, -NHR, -NHCOR etc.

Type 2- All groups having their key atom multiply bonded to more powerful element are meta--directing groups. For example, -NO2, -CN, -COOH, -COR,-SO3H etc.

Type 3- Alkyl groups are ortho, para-directing groups. whereas -CX3,-(NR3)+ are meta--directing groups.

The directive influence can easily be decided by drawing the resonating structures of the intermediate after ortho, meta or para - attack and comparing their stabilities.