2-Nitrochlorobenzene

2-Nitrochlorobenzene is an organic compound with the formula ClC6H4NO2. It is one of three isomeric nitrochlorobenzenes.[1] It is a yellow crystalline solid that is important as a precursor to other compounds due to its two functional groups.

2-Nitrochlorobenzene
Names
Preferred IUPAC name
1-Chloro-2-nitrobenzene
Other names
2-Chloronitrobenzene
Identifiers
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.001.686
EC Number
  • 201-854-9
KEGG
RTECS number
  • CZ0875000
UNII
UN number 1578
  • InChI=1S/C6H4ClNO2/c7-5-3-1-2-4-6(5)8(9)10/h1-4H
    Key: BFCFYVKQTRLZHA-UHFFFAOYSA-N
  • InChI=1/C6H4ClNO2/c7-5-3-1-2-4-6(5)8(9)10/h1-4H
    Key: BFCFYVKQTRLZHA-UHFFFAOYAA
  • C1=CC=C(C(=C1)[N+](=O)[O-])Cl
Properties
C6H4ClNO2
Molar mass 157.55 g·mol−1
Appearance Yellow crystals
Density 1.368 g/mL
Melting point 33 °C (91 °F; 306 K)
Boiling point 245.5 °C (473.9 °F; 518.6 K)
Insoluble
Solubility in other solvents Highly soluble in diethyl ether, benzene, and hot ethanol
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 Toxic, Irritant
GHS labelling:
GHS06: ToxicGHS07: Exclamation markGHS08: Health hazardGHS09: Environmental hazard
Danger
H301, H302, H311, H312, H317, H331, H332, H350, H351, H361, H372, H411
P201, P202, P260, P261, P264, P270, P271, P272, P273, P280, P281, P301+P310, P301+P312, P302+P352, P304+P312, P304+P340, P308+P313, P311, P312, P314, P321, P322, P330, P333+P313, P361, P363, P391, P403+P233, P405, P501
Flash point 124 °C (255 °F; 397 K)
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

Synthesis

Nitrochlorobenzene is typically synthesized by nitration of chlorobenzene in the presence of sulfuric acid:

C6H5Cl + HNO3 → O2NC6H4Cl + H2O

This reaction affords a mixture of isomers. Using an acid ratio of 30% nitric acid, 56% sulfuric acid and 14% water, the product mix is typically 34-36% 2-nitrochlorobenzene and 63-65% 4-nitrochlorobenzene, with only about 1% 3-nitrochlorobenzene.

Reactions

Alkylation and electrophilic aromatic substitution can occur at the chlorinated carbon center, and a diverse array of reactions can be carried out using the nitro group.[1] 2-Nitrochlorobenzene can be reduced to the 2-chloroaniline with Fe/HCl mixture, the Bechamp reduction.

2-Nitrochlorobenzene, like its isomers, is reactive toward nucleophiles, resulting in chloride substitution. With polysulfide, it reacts to give di-orthonitrophenyl disulfide:[2]

2 O2NC6H4Cl + Na2S2 → (O2NC6H4S)2 + 2 NaCl

Similarly, it reacts with sodium methoxide to give 2-nitroanisole.

Substitution of chloride by fluoride is also practiced commercially to convert 2-nitrochlorobenzene to 2-fluoronitrobenzene. The Halex process uses potassium fluoride in polar solvents like sulfolane :

O2NC6H4Cl + KF → O2NC6H4F + KCl

Applications

2-Nitrochlorobenzene is not valuable in itself but is a precursor to other useful compounds. The compound is particularly useful because both of its reactive sites can be utilized to create further compounds that are mutually ortho. Its derivative 2-chloroaniline is a precursor to 3,3’-dichlorobenzidine, itself a precursor to many dyes and pesticides.

References
  1. Gerald Booth, "Nitro Compounds, Aromatic" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH: Weinheim, 2005. doi:10.1002/14356007.a17_411
  2. Bogert, Marston T.; Stull, Arthur (1928). "Di-o-Nitrophenyl Disulfide". Organic Syntheses. 8: 64. doi:10.15227/orgsyn.008.0064.
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