4-Nitroaniline, p-nitroaniline or 1-amino-4-nitrobenzene is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula C₆H₆N₂O₂. A yellow solid, it is one of three isomers of nitroaniline. It is an intermediate in the production of dyes, antioxidants, pharmaceuticals, gasoline, gum inhibitors, poultry medicines, and as a corrosion inhibitor.

Synthesis

4-Nitroaniline is produced industrially via the amination of 4-nitrochlorobenzene:] :ClC₆H₄NO₂ + 2 NH₃ → H₂NC₆H₄NO₂ + NH₄Cl Below is a laboratory synthesis of 4-nitroaniline from

aniline Aniline (From , meaning ' indigo shrub', and ''-ine'' indicating a derived substance) is an organic compound with the formula . Consisting of a phenyl group () attached to an amino group (), aniline is the simplest aromatic amine. It is an in ...

. The key step in this reaction sequence is an

electrophilic aromatic substitution Electrophilic aromatic substitution (SEAr) is an organic reaction in which an atom that is attached to an aromatic ring, aromatic system (usually hydrogen) is replaced by an electrophile. Some of the most important electrophilic aromatic substitut ...

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.
Synthesis of nitroaniline

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 Azo dyes are organic compounds bearing the functional group R−N=N−R′, in which R and R′ are usually aryl and substituted aryl groups. They are a commercially important family of azo compounds, i.e. compounds containing the C−N=N−C l ...

It is also a precursor to 2,6-dichloro-4-nitroaniline, also used in dyes.

Laboratory use

Nitroaniline undergoes diazotization, which allows access to

1,4-dinitrobenzene 1,4-Dinitrobenzene is one of three isomers of dinitrobenzene, with the formula C6H4(NO2)2. The 1,4-isomer is most symmetrical. The compound is a yellow solid that is soluble in organic solvents. It is prepared from 4-nitroaniline by diazotizati ...

and nitrophenylarsonic acid. With phosgene, it converts to 4-nitrophenyl

isocyanate In organic chemistry, isocyanate is the functional group with the formula . Organic compounds that contain an isocyanate group are referred to as isocyanates. An organic compound with two isocyanate groups is known as a diisocyanate. Diisocyan ...

Carbon snake demonstration

When mixed with sulfuric acid and heated, it dehydrates and polymerizes explosively into a rigid foam. The exact composition of the foam is unclear, but the process is believed to involve acidic protonation as well as

displacement Displacement may refer to: Physical sciences Mathematics and physics *Displacement (geometry), is the difference between the final and initial position of a point trajectory (for instance, the center of mass of a moving object). The actual path ...

of the amine group by a sulfonic acid moiety. In Carbon snake demo, paranitroaniline can be used instead of sugar, if the experiment is allowed to proceed under an obligatory fumehood. With this method the reaction phase prior to the black snake's appearance is longer, but once complete, the black snake itself rises from the container very rapidly. This reaction may cause an

explosion An explosion is a rapid expansion in volume of a given amount of matter associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Explosions may also be generated ...

if too much sulfuric acid is used.

Toxicity

The compound is toxic by way of inhalation, ingestion, and absorption, and should be handled with care. Its in rats is 750.0 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.

References

External links

Safety (MSDS)data for p-nitroanilineSigma-Aldrich Catalog data
{{DEFAULTSORT:Nitroaniline, 4- Anilines Dyes IARC Group 3 carcinogens Nitrobenzene derivatives Corrosion inhibitors