Nitration is a chemical reaction in which a nitro group (-NO2) is introduced into a molecule, typically through the substitution of a hydrogen atom with a nitro group. This process is commonly employed in organic chemistry to modify or synthesize aromatic compounds.
Definition of Nitration involves a chemical process that involves the introduction of a nitro group (NO2) into a molecule, typically an organic compound. This reaction is commonly used to synthesize nitroaromatic compounds, which have various applications, including the production of explosives, dyes, and pharmaceuticals. Nitration is often achieved by treating a substrate with a mixture of nitric acid (HNO3) and sulfuric acid (H2SO4) under controlled conditions. The reaction is important in both industrial and laboratory settings for the preparation of diverse chemical products.
1. Aromatic Nitration:
2. Electrophilic Aromatic Nitration:
Description: It is the most common type of nitration involving the substitution of a hydrogen atom in an aromatic ring with a nitro group.
Nitration Mechanism: It follows an electrophilic aromatic substitution mechanism of nitration, where the nitronium ion (NO2+) acts as an electrophile.
3. Nitrating Mixture Nitration:
Description: Involves the use of a mixture of concentrated nitric acid (HNO3) and concentrated sulfuric acid (H2SO4) as the nitrating agent.
Application: Often used for the nitration of compounds that are not reactive enough for electrophilic aromatic substitution alone.
4. Mixed Acid Nitration:
Description: Similar to nitrating mixture nitration, it employs a mixture of nitric and sulfuric acids, but the concentrations may vary.
Application: Applied when a milder or more controlled nitration reaction is desired.
5. Friedel-Crafts Nitration:
Description: Nitration of aromatic compounds using a nitrating agent in the presence of a Lewis acid catalyst (usually aluminum chloride, AlCl3).
Application: Useful for substrates that may not react well with conventional nitration conditions.
6. Metal-Mediated Nitration:
Description: Involves the use of metal-based reagents or catalysts to facilitate nitration reactions.
Example: Palladium-catalyzed nitration of aryl chlorides.
Nitration of phenol is a chemical reaction in which a nitro group (−NO2) is introduced into the phenol molecule. This process typically involves the reaction of phenol with a nitrating mixture of concentrated nitric acid (HNO3) and sulfuric acid (H2SO4).
Mild Nitration:
Phenol + HNO3 /H2SO4 → 2-Nitrophenol + 4-Nitrophenol
Vigorous Nitration:
Phenol + 3HNO3/H2SO4 → 2,4,6-Trinitrophenol + 3H2O
Nitration involves the introduction of a nitro group (NO2) into a molecule using key agents:
Role: Source of the nitronium ion (NO2+).
Role: Enhances reactivity by forming the nitronium ion.
Role: Protects sensitive groups during nitration.
Role: Acts as a dehydrating agent.
Role: Provides a suitable reaction environment.
Eg. Dichloromethane, Toluene.
In this section, we will discuss important uses of nitration. Applications of nitration involve
Explosives Production:
Dye Synthesis:
Pharmaceuticals:
Chemical Intermediates:
(Session 2025 - 26)