nitrátion

Nitration is a chemical reaction in which a nitro group (NO2) is introduced into a molecule. This process is fundamental in organic chemistry and is employed in various industrial applications. The most common method of nitration involves the use of a nitrating agent, typically a mixture of concentrated nitric acid and concentrated sulfuric acid, often referred to as "mixed acid." Sulfuric acid acts as a catalyst, protonating nitric acid to generate the nitronium ion (NO2+), which is the electrophile that attacks the organic substrate.

The nitration reaction can occur on aromatic rings, leading to the formation of nitroaromatic compounds. These compounds are important intermediates in the synthesis of dyes, pharmaceuticals, and explosives. For instance, the nitration of benzene yields nitrobenzene, a precursor to aniline. Aliphatic compounds can also be nitrated, although the mechanisms and reagents may differ. Nitration can be carried out using various nitrating agents besides mixed acid, including nitrogen dioxide, nitryl chloride, and organic nitrates, depending on the specific substrate and desired product. The regioselectivity of aromatic nitration is influenced by the substituents already present on the ring, which can direct the incoming nitro group to specific positions. Safety precautions are crucial during nitration reactions due to the highly exothermic nature of the process and the potential hazards associated with strong acids and reactive intermediates.