5. Aromatic Compounds Pi3 Aromatic was used to described some fragrant compounds in early 1gth century Not correct: later they are grouped by chemical behavior (unsaturated compounds that undergo substitution rather than addition) Current: distinguished from aliphatic compounds by electronic configuration5. Aromatic Compounds • Aromatic was used to described some fragrant compounds in early 19th century –Not correct: later they are grouped by chemical behavior (unsaturated compounds that undergo substitution rather than addition) • Current: distinguished from aliphatic compounds by electronic configuration p.153