Nitro Group

Definition

The nitro group (−NO2) is a functional group consisting of a nitrogen atom double-bonded to two oxygen atoms. It is an important substituent in organic chemistry, known for its ability to influence the reactivity and properties of aromatic compounds.

5 Must Know Facts For Your Next Test

1. The nitro group is a strong electron-withdrawing substituent, which can dramatically influence the reactivity and properties of aromatic compounds.
2. In electrophilic aromatic substitution reactions, the nitro group directs incoming electrophiles to the ortho and para positions relative to itself.
3. The nitro group can participate in resonance stabilization, which affects the reactivity and stability of the molecule.
4. The presence of a nitro group on a benzene ring can increase the acidity of adjacent hydrogen atoms, making them more easily removed.
5. Nitro-substituted aromatic compounds are commonly used in the synthesis of polysubstituted benzenes, as the nitro group can be selectively reduced or transformed into other functional groups.

Review Questions

• Explain how the nitro group can influence the reactivity of aromatic compounds in electrophilic aromatic substitution reactions.
  • The nitro group is a strong electron-withdrawing substituent, which can dramatically affect the reactivity of aromatic compounds in electrophilic aromatic substitution reactions. The electron-withdrawing nature of the nitro group reduces the electron density of the aromatic ring, making it less susceptible to electrophilic attack. However, the nitro group also directs incoming electrophiles to the ortho and para positions relative to itself, as these positions become more reactive due to the stabilizing effect of the nitro group's resonance structures.
• Describe how the nitro group can participate in resonance stabilization and how this affects the properties of the molecule.
  • The nitro group can participate in resonance stabilization, which affects the reactivity and stability of the molecule. The nitrogen atom in the nitro group can form multiple resonance structures by delocalizing its electrons across the oxygen atoms. This resonance stabilization reduces the overall reactivity of the nitro group and the aromatic ring, making the molecule more stable. However, the electron-withdrawing nature of the nitro group can also increase the acidity of adjacent hydrogen atoms, making them more easily removed.
• Discuss the role of the nitro group in the synthesis of polysubstituted benzenes and how its transformations can be utilized.
  • The nitro group is commonly used in the synthesis of polysubstituted benzenes due to its versatility. The nitro group can be selectively reduced to an amino group, which can then be further functionalized. Additionally, the nitro group can be transformed into other functional groups, such as hydroxyl or halide groups, through various chemical reactions. This allows for the construction of complex, polysubstituted benzene derivatives starting from a simple nitro-substituted precursor. The ability to selectively modify the nitro group makes it a valuable tool in the synthesis of diverse aromatic compounds.

Related terms

Electrophilic Aromatic Substitution:

A reaction where an electrophile replaces a hydrogen atom on an aromatic ring, often influenced by the presence of substituents like the nitro group.

Resonance Stabilization:

The ability of a molecule or ion to distribute its electrons over multiple atoms, which can be affected by the nitro group's electron-withdrawing nature.

Acidity:

The ability of a compound to donate a proton, which can be altered by the presence of a nitro group on the molecule.