Aromatic Hydrocarbon Reactions

 

I. Substitution Reactions

Aromatic hydrocarbons tend to react more like the alkanes than the alkens. Therefore, expect to see substitution reactions rather than replacement reactions. In these reactions a H atom from the reactant's aromatic ring structure will be replaced by some functional group in the product.

A. Alkylation (Friedel-Crafts) reaction

Benzene
+
Chloroethane
  
Ethylbenzene
+
Hydrochloric acid
  

 

B. Halogenation reactions

Benzene
+
Chlorine
  
Chlorobenzene
+
Hydrochloric acid
  


C. Nitration reaction

Benzene
+
Nitric acid
  
Nitrobenzene
+
Water
  

 

 

 

II. Side-Chain Oxidation Reactions

Note: The carbon atom that is directly attached to the reactant side aromatic ring structure is oxidized to a carboxyl group in the product no matter how many carbon atoms are in the attached substituent.

A.One carbon atom in the substituent

Toluene
 
Benzoic acid
 

B. Two carbon atoms in the substituent

Ethylenzene
 
Benzoic acid
+
Carbon dioxide

C. Three carbon atoms in the substituent

Propylbenzene
+
Nitric acid
  
Benzoic acid
+
Methanoic acid