From Wikipedia, the free encyclopedia
Jump to navigation Jump to search
Skeletal formula of p-nitroaniline
Ball-and-stick model of the p-nitroaniline molecule
Preferred IUPAC name
Systematic IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.002.555
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)
0.8 mg/ml at 18.5 °C (IPCS)
Vapor pressure 0.00002 mmHg (20°C)[1]
-66.43·10−6 cm3/mol
Main hazards Toxic
Safety data sheet JT Baker
Toxic T Dangerous for the Environment (Nature) N
R-phrases (outdated) R23/24/25 R33 R52/53
S-phrases (outdated) S28 S36/37 S45 S61
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogenSpecial hazards (white): no codeNFPA 704 four-colored diamond
Flash point 199 °C (390 °F; 472 K)
Lethal dose or concentration (LD, LC):
3249 mg/kg (rat, oral)
750 mg/kg (rat, oral)
450 mg/kg (guinea pig, oral)
810 mg/kg (mouse, oral)[2]
US health exposure limits (NIOSH):
PEL (Permissible)
TWA 6 mg/m3 (1 ppm) [skin][1]
REL (Recommended)
TWA 3 mg/m3 [skin][1]
IDLH (Immediate danger)
300 mg/m3[1]
Related compounds
Related compounds
2-Nitroaniline, 3-Nitroaniline
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
‹See TfM›☒N verify (what is ☑Y‹See TfM›☒N ?)
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 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.


It is produced industrially via the amination of 4-nitrochlorobenzene:[3]

ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl

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. After this reaction, a separation must be performed to remove 2-nitroaniline, which is also formed in a small amount during the reaction.[4]
Synthesis of nitroaniline.svg


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.[3]

It is a starting material for the synthesis of Para Red, the first azo dye:[5]

When heated with sulfuric acid, it polymerizes explosively into a rigid foam.[6]

Synthesis of Para Red

Laboratory use[edit]

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.[citation needed]


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. 4-Nitroaniline is particularly harmful to all aquatic organisms, and can cause long-term damage to the environment if released as a pollutant.[citation needed]

See also[edit]


  1. ^ a b c d "NIOSH Pocket Guide to Chemical Hazards #0449". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ "p-Nitroaniline". Immediately Dangerous to Life and Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b Gerald Booth (2007). "Nitro Compounds, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_411.
  4. ^ 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.
  5. ^ Williamson, Kenneth L. (2002). Macroscale and Microscale Organic Experiments, Fourth Edition. Houghton-Mifflin. ISBN 0-618-19702-8.
  6. ^ "Studies on nitroaniline–sulfuric acid compositions: Aphrogenic pyrostats". doi:10.1002/app.1970.070140813.

External links[edit]