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 antioxidants commonly found in rubber. Other isomers with the formula ClC₆H₄NO₂ include 2-nitrochlorobenzene and 3-nitrochlorobenzene.

4-nitrochlorobenzene

Names
Preferred IUPAC name 1-Chloro-4-nitrobenzene
Other names 4-Chloro-1-nitrobenzene 4-Chloronitrobenzene p-Nitrochlorobenzene PNCBO
Identifiers
CAS Number	100-00-5 Y
3D model (JSmol)	Interactive image
ChemSpider	21106020 N
ECHA InfoCard	100.002.554
KEGG	C14456 N
PubChem CID	7474
UNII	CVL66U249D N
CompTox Dashboard (EPA)	DTXSID5020281
InChI InChI=1S/C6H4ClNO2/c7-5-1-3-6(4-2-5)8(9)10/h1-4H N Key: CZGCEKJOLUNIFY-UHFFFAOYSA-N N InChI=1/C6H4ClNO2/c7-5-1-3-6(4-2-5)8(9)10/h1-4H Key: CZGCEKJOLUNIFY-UHFFFAOYAO
SMILES C1=CC(=CC=C1[N+](=O)[O-])Cl
Properties
Chemical formula	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)
Solubility in water	Insoluble
Solubility in other solvents	Soluble in toluene, ether, acetone, hot ethanol
Vapor pressure	0.2 mmHg (30°C)[1]
Hazards
Flash point	12 °C (54 °F; 285 K)
Lethal dose or concentration (LD, LC):
LD50 (median dose)	812 mg/kg (rat, oral) 1414 mg/kg (mouse, oral) 440 mg/kg (mouse, oral) 420 mg/kg (rat, oral)[1]
LC50 (median concentration)	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]
Safety data sheet (SDS)	External MSDS
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

Preparation and reactions

4-Nitrochlorobenzene is prepared industrially by nitration of chlorobenzene:

ClC₆H₅ + HNO₃ → ClC₆H₄NO₂ + H₂O

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

The chloride substituent in 4-nitrochlorobenzene is more labile than in chlorobenzene. For example, it is readily displaced by sulfide nucleophiles, leading the way to 4-nitrothiophenol.^[4] In another example, 4-nitrochlorobenzene is a favored substrate for cross-coupling reactions.^[5]

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, fluoride, and amide displace chloride to give respectively 4-nitrophenol, 4-nitroanisole, 4-fluoronitrobenzene, and 4-nitroaniline.^[2][6]

Another 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 U.S. National Institute for Occupational Safety and Health considers 4-nitrochlorobenzene as a potential occupational carcinogen.^[7] The Occupational Safety and Health Administration set a permissible exposure limit of 1 mg/m³ 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.^[8][9]