Thiophene Synthesis

Thiophene Synthesis: Thiophene belongs to a class of heterocyclic compounds containing a five-membered ring made up of one sulfur as a heteroatom. Thiophene is a colorless liquid having a boiling point of 84°C. It was isolated as an impurity in commercial benzene in 1882 by Victor Meyer. It is a π – excessive aromatic heterocycle.

Industrial Methods

Chemical Synthesis of Thiophene

1. Paal-Knorr Synthesis: In this method, 1, 4 – dicarbonyl compounds can be heated with phosphorus pentasulfide (a source of sulfur) to give thiophene.

Paal-Knorr Synthesis of Thiophene

The basic mechanism of this synthetic procedure involves cyclic condensation of 1, 4-diketones (a) with primary amine (pyrrole synthesis), (b) with a sulfur source (thiophene synthesis), or (c) dehydration of diketone (furan synthesis). Phosphorus pentasulfide or bis (trimethylsilyl) sulfide acts as a sulfurizing agent as well as a dehydrating agent. Hydrogen sulfide in the presence of an acid catalyst is also effective.

2. Hinsberg Synthesis: Two consecutive aldol condensations between 1, 2-dicarbonyl compound and diethylthiodiacetate in the presence of a strong base gives thiophene.

Hinsberg Synthesis

3. Fiesselmann Thiophene Synthesis: It is a base-catalyzed condensation reaction of thioglycolic acid with α, and β-acetylenic esters to give 3-hydroxy-2-thiophene carboxylic acid.

Industrial Methods

4. Gewald Aminothiophene Synthesis: It is a base-catalyzed condensation of a ketone with a β–acetonitrile to form an olefin, followed by cyclization with elemental sulfur to give 2-aminothiophenes.

Gewald Aminothiophene Synthesis

5. Industrial Methods:

(1) Thiophene can be synthesized on an industrial scale heating n-butane and sulfur at high temperatures.

Industrial Methods of Thiophene

(2) Using n-butane the sulfur first causes dehydrogenation and then interacts with the alkene by addition. Further dehydrogenation leads to the aromatization of the ring. A mixture of acetylene and hydrogen sulfide is passed through a tube containing alumina at 400°C.

Industrial Methods

(3) A mixture of sodium succinate and phosphorus trisulfide is heated at 200°C to give thiophene.

Thiophene Synthesis
Make sure you also check our other amazing Article on : Furan Reactions
Spread the love

Hello friends I’m Sameer Ray We tried our best to design this website in the way any pharmacy student would like and love to get. They can gather information and content about the pharmacy

Leave a Comment