Chlorobenzene

Chlorobenzene
IUPAC name chlorobenzene
Other names benzene chloride monochlorobenzene Phenyl chloride
Identifiers
CAS number	108-90-7 Y
PubChem	7964
ChemSpider	7676 Y
UNII	K18102WN1G Y
KEGG	C06990 Y
ChEBI	CHEBI:28097 Y
ChEMBL	CHEMBL16200 Y
RTECS number	CZ0175000
Jmol-3D images	Image 1
SMILES c1ccc(cc1)Cl
InChI InChI=1S/C6H5Cl/c7-6-4-2-1-3-5-6/h1-5H Y Key: MVPPADPHJFYWMZ-UHFFFAOYSA-N Y InChI=1/C6H5Cl/c7-6-4-2-1-3-5-6/h1-5H Key: MVPPADPHJFYWMZ-UHFFFAOYAG
Properties
Molecular formula	C6H5Cl
Molar mass	112.56 g/mol
Appearance	colorless liquid
Density	1.11 g/cm³, liquid
Melting point	-45 °C, 228 K, -49 °F
Boiling point	131 °C, 404 K, 268 °F
Solubility in water	low
Solubility in other solvents	soluble in most organic solvents
Hazards
MSDS	External MSDS
R-phrases	R10 R20 R51/53
S-phrases	S24/25 S61
NFPA 704	3 3 0
Flash point	29 °C
Related compounds
Related Halobenzenes	Fluorobenzene Bromobenzene Iodobenzene
Related compounds	benzene 1,4-dichlorobenzene
Supplementary data page
Structure and properties	n, εr, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
Infobox references

Chlorobenzene is an aromatic organic compound with the chemical formula C₆H₅Cl. This colorless, flammable liquid is a common solvent and a widely used intermediate in the manufacture of other chemicals.

Uses

Chlorobenzene once was used in the manufacture of certain pesticides, most notably DDT by reaction with chloral (trichloroacetaldehyde), but this application has declined with the diminished use of DDT. At one time, chlorobenzene was the main precursor for the manufacture of phenol:^[1]

C₆H₅Cl + NaOH → C₆H₅OH + NaCl

The major use of chlorobenzene is as an intermediate in the production of commodities such as herbicides, dyestuffs, and rubber. Chlorobenzene is also used as a high-boiling solvent in many industrial applications as well as in the laboratory.^[2] Chlorobenzene is nitrated on a large scale to give a mixture of 2- and 4-nitrochlorobenzenes, which can be separated by fractional crystallization followed by distillation. 2-Nitrochlorobenzene (CAS#88-73-3) is converted to related 2-nitrophenol, 2-nitroanisole, bis(2-nitrophenyl)disulfide, and 2-nitropaniline by nucleophilic displacement of the chloride with sodium hydroxide, sodium methoxide, sodium disulfide and ammonia. The conversion of the 4-nitrochlorobenzene (CAS#100-00-5) are similar.^[3]

Synthesis

Chlorobenzene was first described in 1851. Presently it is manufactured by chlorination of benzene in the presence of a catalytic amount of Lewis acid such as ferric chloride and anhydrous aluminium chloride:

The catalyst enhances the electrophilicity of the chlorine. Because chlorine is electronegative, C₆H₅Cl exhibits decreased susceptibility to attack by other electrophiles. For this reason, the chlorination process produces only small amounts of dichloro- and trichlorobenzenes.

Safety

Chlorobenzene exhibits "low to moderate" toxicity as indicated by its LD₅₀ of 2.9 g/kg.^[2]

Toxicology

Chlorobenzene is not a naturally occurring compound, but because of its manufacture, can persist in soil for several months, in air for about 3.5 days, and in water for less than one day. Humans may be exposed to this agent via breathing contaminated air (primarily via occupational exposure), eating contaminated food or water, or by coming into contact with contaminated soil (typically near hazardous waste sites). However, because it has only been found at 97 out of 1,177 NPL hazardous waste sites, it is not considered a widespread environmental contaminant.

Upon entering the body, typically via contaminated air, chlorobenzene is excreted both via the lungs and the urinary system.

References

1. ^ Manfred Weber, Markus Weber, Michael Kleine-Boymann, “Phenol” in Ullmann’s Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005. doi:10.1002/14356007.a19 299.pub2
2. ^ ^{a b} Manfred Rossberg et al. “Chlorinated Hydrocarbons” in Ullmann’s Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2006. doi:10.1002/14356007.a06 233.pub2
3. ^ Gerald Booth (2007). "Nitro Compounds, Aromatic". In: Ullmann's Encyclopedia of Industrial Chemistry. John Wiley & Sons: New York. doi:10.1002/14356007.a17_411