Thiophene Preparation and reactions , five-membered ring heterocycle with one heteroatom

Thiophene

Five-membered ring with one hetero atom 

Preparation of Thiophene

Thiophene can be prepared by on of  the following methods

• By heating sodium succinate with phosphorus sulphide
• By heating n-butane with sulphur  
• Using Paal-Knorr synthesis of thiophene derivatives: It involves the action of heat on  1,4-diketone or 1,4-dialdehyde with phosphorous trisulphide
• Thiophene is prepared  by heating  mixture of acetylene and hydrogen sulphide in presence of aluminum oxide

Reactions of Thiophene (Electrophilic substitution reactions)

Thiophene undergoes Electrophilic substitution reaction.  the electrophilic substitution would be expected to take place at position 2 than  position 3.

Nitration: 

Thiophene when nitrated with fuming Nitric acid in presence of acetic anhydride to yield 2-nitrothiophene.

Sulphonation: 

Sulphonation of thiophene with cold concentrated sulfuric acid to yield 2-thiophene sulphonic acid.

Bromination: 

When thiophene is treated with bromine 2,5-dibromothiophene is produced.

Iodination: 

When thiophene is treated with Iodine in the presence of  mercuric oxide, 2-iodothiophene is produced.

Friedel-Craft's Acylation: 

Acylation of thiophene is performed using acetic anhydride and phosphoric acid.