Two Types of Benzene Substituents

Electron donating groups (EDG)/Activators with lone pairs (e.g. -OMe, -NH2) on the atoms adjacent to the π system activate the aromatic ring by increasing the electron density on the ring through a resonance donating effect. o Make benzene ring more nucleophilic by

pushing electrons toward the ring Electron withdrawing

groups/Deactivators (EWG) with p bonds to electronegative atoms (e.g. -C=O, -NO2) adjacent to the π system deactivate the aromatic ring by decreasing the electron density on the ring through a resonance withdrawing effect.o Make benzene ring less nucleophilic

Methyl Benzene Methylbenzene (Toulene) is an example of a

substituted aromatic compound. Methylbenzene is an activated or more reactive

compared to benzene. Methyl group is an activated group/EDG that

increases the rate of reaction.

Methyl group is an ortho/para director- it directs the incoming groups to ortho and para positions.

As the temperature increases, you get increasing proportions of the 4- isomer and less of the 2- isomer because the 4-position is more stable due to less steric clash between the methyl group.

Nitrobenzene Deactivator less reactive than benzene Meta-director

Reaction with Tin in concentrated HCL: Preparing Phenylam ine

The mixture is heated under reflux in a boiling water bath for about half an hour.

Under the acidic conditions, rather than getting phenylamine directly, you instead get phenylammonium ions formed

The lone pair on the nitrogen in the phenylamine picks up a hydrogen ion from the acid.