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The reduction of nitro compounds are chemical reactions of wide interest in organic chemistry. The conversion can be effected by many reagents. The nitro group was one of the first functional groups to be reduced. Alkyl and aryl nitro compounds behave differently. Most useful is the reduction of aryl nitro compounds.
Nitro compounds participate in several organic reactions, the most important being reduction of nitro compounds to the corresponding amines: RNO 2 + 3 H 2 → RNH 2 + 2 H 2 O. Virtually all aromatic amines (e.g. aniline) are derived from nitroaromatics through such catalytic hydrogenation.
Nitroso compounds can be prepared by the reduction of nitro compounds [1] or by the oxidation of hydroxylamines. [2] Ortho-nitrosophenols may be produced by the Baudisch reaction. In the Fischer–Hepp rearrangement, aromatic 4-nitrosoanilines are prepared from the corresponding nitrosamines.
The Béchamp reduction (or Béchamp process) is a chemical reaction that converts aromatic nitro compounds to their corresponding anilines using iron as the reductant: [1] 4 C 6 H 5 NO 2 + 9 Fe + 4 H 2 O → 4 C 6 H 5 NH 2 + 3 Fe 3 O 4. This reaction was once a major route to aniline, but catalytic hydrogenation is the preferred method. [2]
Typical aniline partners are shown below. Since anilines are prepared from nitro compounds, some azo dyes are produced by partial reduction of aromatic nitro compounds. [5] Many azo dyes are produced by reactions from pre-existing azo compounds. Typical reactions include metal complexation and acylation. Illustrative azo dyes or their precursors
The Stephen reduction. The Stephen reduction is less used today, because it has been mostly superseded by diisobutylaluminium hydride reduction. Additionally, SnCl 2 is used to selectively reduce aromatic nitro groups to anilines. [12] Aromatic nitro group reduction using SnCl 2. SnCl 2 also reduces quinones to hydroquinones.
Zinin reaction or Zinin reduction involves reduction of nitro aromatic compounds to the amines using sodium sulfide. [1] It is used to convert nitrobenzenes to anilines. [2] [3] The reaction selectively reduces nitro groups in the presence of other easily reduced functional groups (e.g., aryl halides and C=C bonds) are present in the molecule.
Nitrosation and nitrosylation are two names for the process of converting organic compounds or metal complexes [1] into nitroso derivatives, i.e., compounds containing the R−NO functionality. The synonymy arises because the R-NO functionality can be interpreted two different ways, depending on the physico-chemical environment: