Skeletal formula of p-nitroaniline
Ball-and-stick model of the p-nitroaniline molecule
Crystals of p-nitroaniline.jpg
Preferred IUPAC name
Systematic IUPAC name
Other names
3D model (JSmol)
ECHA InfoCard 100.002.555 Edit this at Wikidata
EC Number
  • 202-810-1
RTECS number
  • BY7000000
UN number 1661
  • InChI=1S/C6H6N2O2/c7-5-1-3-6(4-2-5)8(9)10/h1-4H,7H2 ☒N
  • InChI=1/C6H6N2O2/c7-5-1-3-6(4-2-5)8(9)10/h1-4H,7H2
  • c1cc(ccc1N)N(=O)=O
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
Occupational safety and health (OHS/OSH):
Main hazards
GHS labelling:
GHS06: ToxicGHS08: Health hazard
H301, H311, H331, H373, H412
P260, P261, P264, P270, P271, P273, P280, P301+P310, P302+P352, P304+P340, P311, P312, P314, P321, P322, P330, P361, P363, P403+P233, P405, P501
NFPA 704 (fire 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]
NIOSH (US health exposure limits):
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]
Safety data sheet (SDS) JT Baker
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).
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4-Nitroaniline, p-nitroaniline or 1-amino-4-nitrobenzene is an organic compound 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.[3]


4-Nitroaniline 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. 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.[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]

Synthesis of Para Red

Laboratory use[]

Nitroaniline undergoes diazotization, which allows access to 1,4-dinitrobenzene[6] and nitrophenylarsonic acid.[7] With phosgene, it converts to 4-nitrophenylisocyanate.[8] [9]

Carbon snake demonstration[]

When heated with sulfuric acid, it dehydrates and polymerizes explosively into a rigid foam.[10]

In Carbon snake demo, paranitroaniline can be used instead of sugar, if the experiment is allowed to proceed under an obligatory fumehood.[11] 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.[12] This reaction may cause an explosion if too much sulfuric acid is used.[13]


The compound is toxic by way of inhalation, ingestion, and absorption, and should be handled with care. Its LD50 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.[14]

See also[]


  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 or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b c Gerald Booth (2007). 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. (1997). "Synthesis 5: Synthesis of the Dye Para Red from Aniline". Experimental Organic Chemistry. New York, NY: Freeman. pp. 456–467. Archived from the original on 2020-09-15. Retrieved 2007-07-18.
  5. ^ Williamson, Kenneth L. (2002). Macroscale and Microscale Organic Experiments, Fourth Edition. Houghton-Mifflin. ISBN 0-618-19702-8.
  6. ^ E. B. Starkey (1939). "p-Dinitrobenzene". Org. Synth. 19: 40. doi:10.15227/orgsyn.019.0040.
  7. ^ "P-NITROPHENYLARSONIC ACID". Organic Syntheses. 26: 60. 1946. doi:10.15227/orgsyn.026.0060.
  8. ^ R. L. Shriner, W. H. Horne, and R. F. B. Cox (1934). "p-Nitrophenyl Isocyanate". Organic Syntheses. 14: 72. doi:10.15227/orgsyn.014.0072.{{cite journal}}: CS1 maint: multiple names: authors list (link)
  9. ^ "2,6-DIIODO-p-NITROANILINE". Organic Syntheses. 12: 28. 1932. doi:10.15227/orgsyn.012.0028.
  10. ^ Poshkus, A. C.; Parker, J. A. (1970). "Studies on nitroaniline–sulfuric acid compositions: Aphrogenic pyrostats". Journal of Applied Polymer Science. 14 (8): 2049–2064. doi:10.1002/app.1970.070140813.
  11. ^ Summerlin, Lee R.; Ealy, James L. (1988). "Experiment 100: Dehydration of p-Nitroaniline: Sanke and Puff". Chemical Demonstrations: A Sourcebook for Teachers Volume 1 (2nd ed.). American Chemical Society. p. 171. ISBN 978-0-841-21481-1.
  12. ^ "Carbon Snake: demonstrating the dehydration power of concentrated sulfuric acid". communities.acs.org. 2013-06-06. Retrieved 2022-01-31.
  13. ^ Making a carbon snake with P-Nitroaniline, retrieved 2022-01-31
  14. ^ "4-Nitroaniline". St. Louis, Missouri: Sigma-Aldrich. December 18, 2020.

External links[]