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

Names
Preferred IUPAC name 2-Nitroaniline
Systematic IUPAC name 2-Nitrobenzenamine
Other names ortho-Nitroaniline o-Nitroaniline
Identifiers
CAS Number	88-74-4 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL274009 Y
ChemSpider	13853943 Y
ECHA InfoCard	100.001.687
EC Number	201-855-4
PubChem CID	6946
RTECS number	BY6650000
UNII	2519U0541L
UN number	1661
CompTox Dashboard (EPA)	DTXSID1025726
InChI InChI=1S/C6H6N2O2/c7-5-3-1-2-4-6(5)8(9)10/h1-4H,7H2 N Key: DPJCXCZTLWNFOH-UHFFFAOYSA-N N InChI=1/C6H6N2O2/c7-5-3-1-2-4-6(5)8(9)10/h1-4H,7H2 Key: DPJCXCZTLWNFOH-UHFFFAOYAV
SMILES O=[N+]([O-])c1ccccc1N
Properties
Chemical formula	C6H6N2O2
Molar mass	138.126 g·mol−1
Appearance	Orange solid
Density	1.442 g/ml
Melting point	71.5 °C (160.7 °F; 344.6 K)
Boiling point	284 °C (543 °F; 557 K)
Solubility in water	0.117 g/100 ml (20°C) (SIDS)
Acidity (pKa)	−0.3 (of anilinium salt)
Magnetic susceptibility (χ)	−66.47·10−6 cm3/mol
Hazards
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H301, H311, H331, H373, H412
Precautionary statements	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
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). N verify (what is YN ?) 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.

See also

• 3-Nitroaniline
• 4-Nitroaniline