|Jmol-3D images||Image 1
|Molar mass||147.01 g/mol|
-17.03 °C, 256 K, 1 °F
180.5 °C, 454 K, 357 °F
|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|
| (what is: / ?)
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)
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:
- C6H5Cl + Cl2 → C6H4Cl2 + 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 chlorine, like all halogens, are ortho/para- directors in terms of electrophilic aromatic substitution and the 1,3- isomer is a meta- compound.
It is mainly used as a precursor to 1,2-dichloro-4-nitrobenzene, an intermediate in the synthesis of agrochemicals. 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.
1,2-Dichlorobenzene is also used in softening and removing carbon-based contamination on metal surfaces.
See also 
- Merck Index, 11th Edition, 3044
- Gerald Booth (2007). "Nitro Compounds, Aromatic" in Ullmann's Encyclopedia of Industrial Chemistry Wiley-VCH, Weinheim, 2005.
- Technical Order 2J-1-13