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

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

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 4-Nitrochlorobenzene is the organic compound with the formula ClC6H4NO2. It is a pale yellow solid. 4-Nitrochlorobenzene is a common intermediate in the production of a number of industrially useful compounds, including common antioxidants found ...

: :ClC₆H₄NO₂ + 2 NH₃ → H₂NC₆H₄NO₂ + NH₄Cl Below is a laboratory synthesis of 4-nitroaniline from

aniline Aniline is an organic compound with the formula C6 H5 NH2. Consisting of a phenyl group attached to an amino group, aniline is the simplest aromatic amine. It is an industrially significant commodity chemical, as well as a versatile starti ...

. The key step in this reaction sequence is an

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

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 ...

Laboratory use

Nitroaniline undergoes

diazotization Diazonium compounds or diazonium salts are a group of organic compounds sharing a common functional group where R can be any organic group, such as an alkyl or an aryl, and X is an inorganic or organic anion, such as a halide. General propert ...

, which allows access to

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

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 heated with sulfuric acid, it dehydrates and polymerizes explosively into a rigid foam. In

Carbon snake Carbon snake is a demonstration of the dehydration reaction of sugar by concentrated sulfuric acid. With concentrated sulfuric acid, granulated table sugar ( sucrose) performs a degradation reaction which changes its form to a black solid-liquid ...

demo, paranitroaniline can be used instead of sugar, if the experiment is allowed to proceed under an obligatory

fumehood A fume hood (sometimes called a fume cupboard or fume closet) is a type of local ventilation device that is designed to limit exposure to hazardous or toxic fumes, vapors or dusts. Description A fume hood is typically a large piece of equipm ...

. 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 associated with an extreme outward release of energy, usually with the generation of high temperatures and release of high-pressure gases. Supersonic explosions created by high explosives are known ...

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 Hazardous air pollutants IARC Group 3 carcinogens Nitrobenzenes Corrosion inhibitors