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CAS number 100-01-6 YesY
ChemSpider 13846959 N
Jmol-3D images Image 1
Molecular formula C6H6N2O2
Molar mass 138.12 g/mol
Appearance yellow or brown powder
Odor faint, ammonia-like
Density 1.437 g/ml, solid
Melting point 146 to 149 °C (295 to 300 °F; 419 to 422 K) (lit.)
Boiling point 332 °C (630 °F; 605 K)
Solubility in water 0.8 mg/ml at 18.5°C (IPCS)
EU classification Toxic T Dangerous for the Environment (Nature) N
R-phrases R23/24/25 R33 R52/53
S-phrases S28 S36/37 S45 S61
Main hazards Toxic
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 199 °C (390 °F; 472 K)
Related compounds
Related compounds 2-Nitroaniline, 3-Nitroaniline
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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Infobox references

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 phenyl group attached to an amino group which is para to a nitro group. This chemical is commonly used as an intermediate in the synthesis of dyes, antioxidants, pharmaceuticals and gasoline, in gum inhibitors, poultry medicines, and as a corrosion inhibitor.


It is produced industrially via the amination of 4-nitrochlorobenzene:[1]

ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl

Below is a laboratory synthesis of p-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. After this reaction, a separation must be performed to remove 2-nitroaniline, which is also formed in a small amount during the reaction.[2]
Synthesis of nitroaniline.svg


4-Nitroaniline is mainly consumed industrially as a precursor to p-phenylenediamine, an important dye. The reduction is effected using iron metal and by catalytic hydrogenation.[1]

It is a starting material for the synthesis of Para Red, the first Azo dye:[3]

Synthesis of Para Red


The compound is toxic by way of inhalation, ingestion, and absorption, and should be handled with care. Its LD50 in rats is 750 mg/kg when administered orally. p-Nitroaniline is particularly harmful to all aquatic organisms, and can cause long-term damage to the environment if released as a pollutant.


  1. ^ a b Gerald Booth "Nitro Compounds, Aromatic in Ullmann's Encyclopedia of Industrial Chemistry, 7th Ed.; Wiley-VCH: Weinheim, 2005. doi:10.1002/14356007.a17_411
  2. ^ Mohrig, J.R.; Morrill, T.C.; Hammond, C.N.; Neckers, D.C. "Synthesis 5: Synthesis of the Dye Para Red from Aniline." Experimental Organic Chemistry. Freeman: New York, NY, 1997; pp 456-467.
  3. ^ Williamson, Kenneth L. (2002). Macroscale and Microscale Organic Experiments, Fourth Edition. Houghton-Mifflin. ISBN 0-618-19702-8. 

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