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Synthesis, Reactions and Medicinal Uses of Thiophene

1,4-dicarbonyl compounds can be heated with sulfur-containing compounds (phosphorus pentasulfide) to give thiophene.

Thiophene

Synthesis

Paal-Knorr synthesis - 1,4-dicarbonyl compounds can be heated with sulfur-containing compounds (phosphorus pentasulfide) to give thiophene.


Basically, 1, 4-diketones are cyclically combined to form 1, 5-diphenyl compounds
  • By synthesizing primary amines,
  • Based on thiophene synthesis (sulfur source),
  • Diketone is dehydrated (furan synthesis).
Pentasulfide of phosphorus and bis (trimethylsilyl) sulfide of silica can both dehydrate and sulfurize. Hydrogen sulfide can also be used when combined with an acid catalyst.

Gewald Aminothiophene synthesis - Base-catalyzed condensation of a ketone with a β-acetonitrile yields an olefin, which is the precursor for 2-aminothiophenes upon cyclization with sulfur.


Industrial methods -

At high temperatures, n-butane and sulfur can be heated to produce thiophene on an industrial scale.


First, the sulfur dehydrates n-butane, and then it adds to alkene by dehydrogenation. The ring is also aromatized during further dehydrogenation. In a tube containing alumina at 400°C, acetylene and hydrogen sulfide are passed.


Sodium succinate and phosphorus trisulfide are heated to 200°C to form thiophene.



Reactions

In comparison with benzene, triphenyl is a bit more nucleophilic. C2 atoms accumulate a greater amount of negative charge than C5 atoms. The positive charge is on sulfur. The C2 - and C5 - positions in the molecule can be easily substituted by electrophilic compounds.

Protonation - Acids have little effect on thiophene. Hot phosphoric acid, for example, produces thiophene trimer when exposed to very strong acids.


Oxidation - Stability of the thiophene ring is not affected by oxidizing agents. A carboxylic acid group can, however, be formed from the side chains. A ring's maleic acid and oxalic acid are released when heated with nitric acid.
Electrophilic substitution - Pyrole is more reactive than furan, thiophene is more reactive than benzene, and pyrrole is more reactive than furan. The C2-position of thiophene is the most common site of attack.


Nucleophilic reaction - Substituted thiophenes containing electron-withdrawing substituents have a much higher nucleophilicity.



Reduction -



Medicinal Uses

Among the remarkable properties of thiophene derivatives are antibacterial, anti-inflammatory, anti-anxiety, antipsychotic, antiarrhythmic, and anticancer effects.
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Ankur Choudhary is India's first professional pharmaceutical blogger, author and founder of Pharmaceutical Guidelines, a widely-read pharmaceutical blog since 2008. Sign-up for the free email updates for your daily dose of pharmaceutical tips.
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