Chlorobenzene

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Chlorobenzene
Chlorobenzene2.svg Chlorobenzene
Chlorobenzene.png
Identifiers
CAS number 108-90-7 YesY
PubChem 7964
ChemSpider 7676 YesY
UNII K18102WN1G YesY
KEGG C06990 YesY
ChEBI CHEBI:28097 YesY
ChEMBL CHEMBL16200 YesY
RTECS number CZ0175000
Jmol-3D images Image 1
Properties
Molecular formula C6H5Cl
Molar mass 112.56 g/mol
Appearance colorless liquid
Density 1.11 g/cm³, liquid
Melting point −45 °C (−49 °F; 228 K)
Boiling point 131 °C (268 °F; 404 K)
Solubility in water 0.5 g l-1 in water at 20 °C
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
Flammability code 3: Liquids and solids that can be ignited under almost all ambient temperature conditions. Flash point between 23 and 38 °C (73 and 100 °F). E.g., gasoline) Health code 3: Short exposure could cause serious temporary or residual injury. E.g., chlorine gas Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
Flash point 29 °C (84 °F; 302 K)
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
Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
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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[edit]

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-nitroaniline 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]

Production[edit]

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, sulfur dichloride, and anhydrous aluminium chloride:[4]

Chlorination benzene.svg

The catalyst enhances the electrophilicity of the chlorine. Because chlorine is electronegative, C6H5Cl exhibits somewhat decreased susceptibility to further chlorination. Industrially the reaction is conducted as a continuous process to minimize the formation of dichlorobenzenes.

Biodegradation[edit]

Rhodococcus phenolicus is a bacterium species able to degrade chlorobenzene as sole carbon sources.[5]

Safety[edit]

Chlorobenzene exhibits "low to moderate" toxicity as indicated by its LD50 of 2.9 g/kg.[2] The Occupational Safety and Health Administration has set a permissible exposure limit at 75 ppm (350 mg/m3) over an eight hour time-weighted average for workers handling chlorobenzene.[6]

Toxicology[edit]

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[edit]

  1. ^ Weber, Manfred; Weber, Markus; Kleine-Boymann, Michael (2004). "Phenol". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a19_299.pub2. ISBN 3527306730. 
  2. ^ a b Rossberg, Manfred; Lendle, Wilhelm; Pfleiderer, Gerhard; Tögel, Adolf; Dreher, Eberhard-Ludwig; Langer, Ernst; Rassaerts, Heinz; Kleinschmidt, Peter; Strack, Heinz; Cook, Richard; Beck, Uwe; Lipper, Karl-August; Torkelson, Theodore R.; Löser, Eckhard; Beutel, Klaus K.; Mann, Trevor (2006). "Chlorinated Hydrocarbons". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a06_233.pub2. ISBN 3527306730. 
  3. ^ Booth, Gerald (2000). "Nitro Compounds, Aromatic". Ullmann's Encyclopedia of Industrial Chemistry. doi:10.1002/14356007.a17_411. ISBN 3527306730. 
  4. ^ U. Beck, E. Löser "Chlorinated Benzenes and other Nucleus-Chlorinated Aromatic Hydrocarbons" Ullmann's Encyclopedia of Industrial Chemistry, 2012, Wiley-VCH, Weinheim. doi:10.1002/14356007.o06_o03
  5. ^ Rehfuss, M.; Urban, J. (2005). "Rhodococcus phenolicus sp. nov., a novel bioprocessor isolated actinomycete with the ability to degrade chlorobenzene, dichlorobenzene and phenol as sole carbon sources". Systematic and Applied Microbiology 28 (8): 695–701. doi:10.1016/j.syapm.2005.05.011. PMID 16261859.  edit Erratum: Rehfuss, M. (2006). "Erratum to "Rhodococcus phenolicus sp. nov., a novel bioprocessor isolated actinomycete with the ability to degrade chlorobenzene, dichlorobenzene and phenol as sole carbon sources" [Systematic and Applied Microbiology 28 (2005) 695–701]". Systematic and Applied Microbiology 29 (2): 182–110. doi:10.1016/j.syapm.2005.11.005.  edit
  6. ^ CDC - NIOSH Pocket Guide to Chemical Hazards