Aromatic Hydrocarbons
Introduction
• The term aromatic is derived from Greek word aroma meaning pleasant odour.
• Originally, the term aromatic was used to represent a group of organic compound
from natural sources which had pleasant odour.
• Later, it was found that almost such compound contained benzene or derivatives of
• Hence, aromatic compounds are benzene and the compounds that resemble b
chemical behaviour.
• However, Aromatic compounds represent only cyclic organic compounds which
with cyclic cloud of pi-electrons and quite stable towards addition reaction e
unsaturated.
• Aromatic hydrocarbons are also called arene. And the general formula of arene
where, n= no. of carbon atoms and y= no. of rings. Some examples are…
, naphthalene anthracene
benzene CH3 CH2CH3 CH3
CH3
phenanthrene toluene ethylbenzene o-xylene
, • Characteristics of Aromatic Compounds
1. They are cyclic compounds having planar ring and cyclic cloud of pi-electrons.
2. Although they are unsaturated, they do not give addition reaction easily.(i.e.
apparent unsaturation)
3. They give electrophilic substitution reactions regardless of functional group.
4. They have high proportion of carbon as compared to its aliphatic analog. Ther
burn with sooty flame. (aliphatic compounds burn with non-sooty flame)
5. They follow Huckel’s (4n+2) rule.
Introduction
• The term aromatic is derived from Greek word aroma meaning pleasant odour.
• Originally, the term aromatic was used to represent a group of organic compound
from natural sources which had pleasant odour.
• Later, it was found that almost such compound contained benzene or derivatives of
• Hence, aromatic compounds are benzene and the compounds that resemble b
chemical behaviour.
• However, Aromatic compounds represent only cyclic organic compounds which
with cyclic cloud of pi-electrons and quite stable towards addition reaction e
unsaturated.
• Aromatic hydrocarbons are also called arene. And the general formula of arene
where, n= no. of carbon atoms and y= no. of rings. Some examples are…
, naphthalene anthracene
benzene CH3 CH2CH3 CH3
CH3
phenanthrene toluene ethylbenzene o-xylene
, • Characteristics of Aromatic Compounds
1. They are cyclic compounds having planar ring and cyclic cloud of pi-electrons.
2. Although they are unsaturated, they do not give addition reaction easily.(i.e.
apparent unsaturation)
3. They give electrophilic substitution reactions regardless of functional group.
4. They have high proportion of carbon as compared to its aliphatic analog. Ther
burn with sooty flame. (aliphatic compounds burn with non-sooty flame)
5. They follow Huckel’s (4n+2) rule.
