2-Nitroaniline

2-Nitroaniline is an organic compound with the formula H2NC6H4NO2. It is a derivative of aniline, carrying a nitro functional group in position 2.[1] It is mainly used as a precursor to o-phenylenediamine.

2-Nitroaniline
Skeletal formula of 2-nitroaniline
Ball-and-stick model of the 2-nitroaniline molecule
Names
Preferred IUPAC name
2-Nitroaniline
Systematic IUPAC name
2-Nitrobenzenamine
Other names
ortho-Nitroaniline
o-Nitroaniline
Identifiers
3D model (JSmol)
ChEMBL
ChemSpider
ECHA InfoCard 100.001.687
EC Number
  • 201-855-4
RTECS number
  • BY6650000
UNII
UN number 1661
Properties
C6H6N2O2
Molar mass 138.126 g·mol−1
Appearance Orange solid
Density 1.442 g/mol
Melting point 71.5 °C (160.7 °F; 344.6 K)
Boiling point 284 °C (543 °F; 557 K)
0.117 g/100 ml (20°C) (SIDS)
Acidity (pKa) -0.3 (of anilinium salt)
-66.47·10−6 cm3/mol
Hazards
GHS pictograms
GHS Signal word Danger
GHS hazard statements
 H301, H311, H331, H373, H412
P260, P261, P264, P270, P271, P273, P280, P301+310, P302+352, P304+340, P311, P312, P314, P321, P322, P330, P361, P363, P403+233, P405, P501
Flash point 168 °C (334 °F; 441 K)
Related compounds
Related compounds
 3-Nitroaniline, 4-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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Infobox references

Synthesis

2-Nitroaniline is prepared commercially by the reaction of 2-nitrochlorobenzene with ammonia:[2]

ClC6H4NO2 + 2 NH3 → H2NC6H4NO2 + NH4Cl

Many other methods exist for the synthesis of this compound. Direct nitration of aniline is inefficient since anilinium is produced instead. Nitration of acetanilide gives only traces of 2-nitro isomer is obtained due to the great steric effect of the amide. Sulfonation is usually used to block the 4 position and increases the effectiveness to 56%.[3][4]

Laboratory routes to produce 2-nitroaniline

Uses and reactions

2-Nitroaniline is the main precursor to phenylenediamines, which are converted to benzimidazoles, a family of heterocycles that are key components in pharmaceuticals.[2]

Intramolecular hydrogen-bonding results in a very low basicity for 2-nitroaniline.

Aside from its reduction to phenylenediamine, 2-nitroaniline undergoes other reactions anticipated for aromatic amines. It is protonated to give the anilinium salts. Owing to the influence of the nitro substituent, the amine exhibits a basicity nearly 100,000x lower than aniline itself. Diazotization gives diazonium derivative,[5] which is a precursor to some diazo dyes. Acetylation affords 2-nitroacetanilide.

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See also

References
  1. Safety data for o-nitroaniline
  2. Gerald Booth (2007). "Nitro Compounds, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_411.
  3. T. W. Grahan, Solomons; Craig, B. Fryhle; Scott, A. Snyder (2011). Organic chemistry (11 ed.). pp. 606–607. ISBN 978-1119077251.
  4. Louis Ehrenfeld, Milton Puterbaugh (1929). "o-Nitrianiline". Organic Syntheses. 9: 64. doi:10.15227/orgsyn.009.0064.
  5. G. Wittig; R. W. Hoffmann (1967). "1,2,3-Benzothiadiazole 1,1-Dioxide". Org. Synth. 47: 4. doi:10.15227/orgsyn.047.0004.
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