Synthesis of Dapsone and Metronidazole

 

Synthesis of Dapsone (4,4'-Diaminodiphenyl sulfone)

Dapsone is an antimicrobial agent primarily used to treat leprosy and dermatitis herpetiformis. The synthesis typically involves the following steps:

1. Nitration of Diphenyl Sulfide

• Reaction: Diphenyl sulfide (C₆H₅-S-C₆H₅) is nitrated using a nitrating mixture of concentrated sulfuric acid (H₂SO₄) and nitric acid (HNO₃).
• Product: 4,4'-dinitrodiphenyl sulfide (NO₂-C₆H₄-S-C₆H₄-NO₂).

2. Oxidation of Dinitrodiphenyl Sulfide

• Reaction: The 4,4'-dinitrodiphenyl sulfide is oxidized using an oxidizing agent like potassium permanganate (KMnO₄) or hydrogen peroxide (H₂O₂).
• Product: 4,4'-dinitrodiphenyl sulfone (NO₂-C₆H₄-SO₂-C₆H₄-NO₂).

3. Reduction of Dinitrodiphenyl Sulfone

• Reaction: The 4,4'-dinitrodiphenyl sulfone undergoes catalytic hydrogenation or reduction using iron (Fe) and hydrochloric acid (HCl), or another reducing agent like tin (Sn) with HCl.
• Product: 4,4'-diaminodiphenyl sulfone (NH₂-C₆H₄-SO₂-C₆H₄-NH₂), which is Dapsone.

Synthesis of Metronidazole

Metronidazole is an antibiotic and antiprotozoal agent commonly used for anaerobic infections. The synthesis involves the preparation of a nitroimidazole ring with a hydroxyl-ethyl side chain.

1. Synthesis of 2-Methyl-5-nitroimidazole

• Reaction: Glyoxal (OHC-CHO), ammonium acetate (NH₄OAc), and nitromethane (CH₃NO₂) react in the presence of acetic acid (CH₃COOH) to form 2-methyl-5-nitroimidazole.
• Product: 2-Methyl-5-nitroimidazole (C₄H₅N₃O₂).

2. Alkylation of 2-Methyl-5-nitroimidazole

• Reaction: The 2-methyl-5-nitroimidazole is alkylated by reacting with ethylene oxide (C₂H₄O) or 2-chloroethanol (ClCH₂CH₂OH) in the presence of a base.
• Product: 1-(2-hydroxyethyl)-2-methyl-5-nitroimidazole, which is Metronidazole.

These are concise routes for synthesizing Dapsone and Metronidazole. Let me know if you need further details or reaction mechanisms.