IUPAC name
Other names
ortho-Dichlorobenzene, o-Dichlorobenzene, odcb, o-Dichlorobenzol
95-50-1 YesY
3D model (Jmol) Interactive image
Interactive image
ChEBI CHEBI:35290 YesY
ChEMBL ChEMBL298461 YesY
ChemSpider 13837988 YesY
ECHA InfoCard 100.002.206
EC Number 202-425-9
KEGG C14328 YesY
PubChem 7239
Molar mass 147.01 g/mol
Density 1.30 g/cm3
Melting point −17.03 °C (1.35 °F; 256.12 K)
Boiling point 180.5 °C (356.9 °F; 453.6 K)
Vapor pressure 1 mmHg (20° C)
Safety data sheet External MSDS
Ingestion hazard Toxic if swallowed
Inhalation hazard Causes respiratory tract irritation
Eye hazard Causes eye irritation
Skin hazard Causes skin irritation
Flash point 66 °C (151 °F; 339 K)
Explosive limits 2.2%-9.2%[2]
Lethal dose or concentration (LD, LC):
500 mg/kg (oral, rat, rabbit)
2000 mg/kg (oral, guinea pig)
4386 mg/kg (oral, mouse)[3]
1000 ppm (guinea pig, 20 hr)
800 ppm (guinea pig, 24 hr)
821 ppm (rat, 7 hr)[3]
US health exposure limits (NIOSH):
PEL (Permissible)
C 50 ppm (300 mg/m3)[2]
REL (Recommended)
C 50 ppm (300 mg/m3)[2]
IDLH (Immediate danger)
200 ppm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YesYN ?)
Infobox references

1,2-Dichlorobenzene, or orthodichlorobenzene (ODCB), is an organic compound with the formula C6H4Cl2. This colourless liquid is poorly soluble in water but miscible with most organic solvents. It is a derivative of benzene, consisting of two adjacent chlorine centers.

Production and uses

1,2-Dichlorobenzene is obtained as a side-product of the production of chlorobenzene:

+ Cl
+ HCl

The reaction also affords the 1,4- and small amounts of the 1,3-isomer. The 1,4- isomer is preferred over the 1,2- isomer due to steric hindrance. The 1,3- isomer is uncommon because it is a meta- compound, while chlorine, like all halogens, is a ortho/para- directors in terms of electrophilic aromatic substitution.

It is mainly used as a precursor to 1,2-dichloro-4-nitrobenzene, an intermediate in the synthesis of agrochemicals.[4] In terms of niche applications, 1,2-dichlorobenzene is a versatile, high-boiling solvent. It is a preferred solvent for dissolving and working with fullerenes. It is an insecticide for termites and locust borers, historically used by the United States Forest Service to combat widespread bark beetle outbreaks.[5]

1,2-Dichlorobenzene is also used in softening and removing carbon-based contamination on metal surfaces.[6]


Data from human exposure to 1,2-dichlorobenzene shows that concentrations of 100 ppm have been reported to cause sporadic irritation of the eyes and respiratory tract.[7] The Occupational Safety and Health Administration and the National Institute for Occupational Safety and Health have set occupational exposure limits at a ceiling of 50 ppm, over an eight-hour workday.[8]

See also


  1. Merck Index, 11th Edition, 3044
  2. 1 2 3 4 5 "NIOSH Pocket Guide to Chemical Hazards #0189". National Institute for Occupational Safety and Health (NIOSH).
  3. 1 2 "o-Dichlorobenzene". National Institute for Occupational Safety and Health (NIOSH). 4 December 2014. Retrieved 6 March 2015.
  4. Gerald Booth (2007). "Nitro Compounds, Aromatic" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005.
  5. https://www.youtube.com/watch?v=axs2jR2HC6I
  6. Technical Order 2J-1-13
  7. CDC - Documentation for Immediately Dangerous To Life or Health Concentrations (IDLHs)
  8. CDC - NIOSH Pocket Guide to Chemical Hazards
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