4-Nitroaniline

4-Nitroaniline, p-nitroaniline or 1-amino-4-nitrobenzene is an organic compound with the formula C6H6N2O2. It is an organic chemical compound, consisting of a benzene ring in which an amino group is para to a nitro group. This chemical is commonly used as an intermediate in the synthesis of dyes, antioxidants, pharmaceuticals, gasoline, gum inhibitors, poultry medicines, and as a corrosion inhibitor.
Synthesis.
It is produced industrially via the amination of 4-nitrochlorobenzene:
Below is a laboratory synthesis of 4-nitroaniline from aniline. The key step in this reaction sequence is an electrophilic aromatic substitution to install the nitro group "para" to the amino group. The amino group can be easily protonated and become a meta director. Therefore, a protection of the acetyl group is required. After this reaction, a separation must be performed to remove 2-nitroaniline, which is also formed in a small amount during the reaction.
Applications.
4-Nitroaniline is mainly consumed industrially as a precursor to "p"-phenylenediamine, an important dye component. The reduction is effected using iron metal and by catalytic hydrogenation.
It is a starting material for the synthesis of Para Red, the first azo dye:
When heated with sulfuric acid, it polymerizes explosively into a rigid foam.
Laboratory use.
Nitroaniline is a solvatochromic dye used for determining Kamlet-Taft solvent parameters. The position of its UV-visual peak changes with the balance of hydrogen bonding acceptors and donors in the solvent.
Toxicity.
The compound is toxic by way of inhalation, ingestion, and absorption, and should be handled with care. Its in rats is 750 mg/kg when administered orally. 4-Nitroaniline is particularly harmful to all aquatic organisms, and can cause long-term damage to the environment if released as a pollutant.