4-Nitrochlorobenzene

4-Nitrochlorobenzene is the organic compound with the formula ClC6H4NO2. It is a pale yellow solid. 4-Nitrochlorobenzene is a common intermediate in the production of a number of industrially useful compounds, including common antioxidants found in rubber. Other isomers with the formula ClC6H4NO2 include 2-nitrochlorobenzene and 3-nitrochlorobenzene.

4-nitrochlorobenzene
Skeletal formula of 4-nitrochlorobenzene
Ball-and-stick model of the 4-nitrochlorobenzene molecule
Names
Preferred IUPAC name
1-Chloro-4-nitrobenzene
Other names
4-Chloro-1-nitrobenzene
4-Chloronitrobenzene
p-Nitrochlorobenzene
PNCBO
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.002.554
KEGG
UNII
Properties
C6H4ClNO2
Molar mass 157.55 g·mol−1
Appearance Light yellow solid
Odor sweet[1]
Density 1.52 g/cm3 (20 °C)
Melting point 83.6 °C (182.5 °F; 356.8 K)
Boiling point 242.0 °C (467.6 °F; 515.1 K)
Insoluble
Solubility in other solvents Soluble in toluene, ether, acetone, hot ethanol
Vapor pressure 0.2 mmHg (30°C)[1]
Hazards
Safety data sheet External MSDS
Flash point 12 °C (54 °F; 285 K)
Lethal dose or concentration (LD, LC):
812 mg/kg (rat, oral)
1414 mg/kg (mouse, oral)
440 mg/kg (mouse, oral)
420 mg/kg (rat, oral)[1]
164 mg/m3 (cat, 7 hr)[1]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 1 mg/m3 [skin][1]
REL (Recommended)
 Ca[1]
IDLH (Immediate danger)
 Ca [100 mg/m3][1]
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

Preparation

4-Nitrochlorobenzene is prepared industrially by nitration of chlorobenzene:[2]

This reaction affords both the 2- and the 4-nitro derivatives, in about a 1:2 ratio. These isomers are separated by distillation. 4-Nitrochlorobenzene was originally prepared by the nitration of 4-bromochlorobenzene by Holleman and coworkers.[3]

Applications

4-Nitrochlorobenzene is an intermediate in the preparation of a variety of derivatives. Nitration gives 2,4-dinitrochlorobenzene, and 3,4-dichloronitrobenzene. Reduction with iron metal gives 4-chloroaniline. The electron-withdrawing nature of the appended nitro-group makes the benzene ring especially susceptible to nucleophilic aromatic substitution, unlike related chlorobenzene. Thus, the strong nucleophiles hydroxide, methoxide, and amide displace chloride to give respectively 4-nitrophenol, 4-nitroanisole, 4-nitroaniline.[2]

Another major use of 4-nitrochlorobenzene is its condensation with aniline to produce 4-nitrodiphenylamine. Reductive alkylation of the nitro group affords secondary aryl amines, which are useful antioxidants for rubber.

4-Nitrochlorobenzene is the precursor to the anti-leprosy drug Dapsone (4-[(4-aminobenzene)sulfonyl]aniline).[2]

Safety

The National Institute for Occupational Safety and Health considers 4-nitrochlorobenzene as a potential occupational carcinogen that may be absorbed through the skin.[4] The Occupational Safety and Health Administration set a permissible exposure limit of 1 mg/m3, while the American Conference of Governmental Industrial Hygienists recommends an airborne exposure limit of 0.64 mg/m3, over a time-weighted average of eight hours.[5][6]

References
  1. NIOSH Pocket Guide to Chemical Hazards. "#0452". National Institute for Occupational Safety and Health (NIOSH).
  2. Gerald Booth (2007). "Nitro Compounds, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.a17_411. ISBN 978-3527306732.
  3. "The nitration of mixed dihalogen benzenes" Recueil des Travaux Chimiques des Pays-Bas et de la Belgique. Amsterdam, 1915; pp. 204-235.
  4. CDC - Immediately Dangerous to Life or Health Concentrations (IDLH): p-nitrochlorobenzene
  5. CDC - NIOSH Pocket Guide to Chemical Hazards
  6. New Jersey Department of Health and Senior Services - Hazardous Substance Fact Sheet
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