1,2-Dichloroethylene

Chemical compound From Wikipedia, the free encyclopedia

1,2-Dichloroethylene (1,2-DCE) is a pair of organochlorine compounds with the molecular formula C2H2Cl2. The two compounds are isomers, each being colorless liquids with a sweet odor. It can exist as either of two geometric isomers, cis-1,2-dichloroethene or trans-1,2-dichloroethene, but is often used as a mixture of the two. They have modest solubility in water. These compounds have some applications as a degreasing solvent.[1] In contrast to most cis-trans compounds, the Z isomer (cis) is more stable than the E isomer (trans) by 0.4 kcal/mol.[4]

Quick facts Names, Identifiers ...
1,2-Dichloroethylene
Skeletal formula of cis-1,2-dichloroethene
Skeletal formula of cis-1,2-dichloroethene
Skeletal formula of trans-1,2-dichloroethene
Skeletal formula of trans-1,2-dichloroethene
Ball-and-stick model of cis-1,2-dichloroethene
Ball-and-stick model of cis-1,2-dichloroethene
cis-1,2-Dichloroethene (Z)
Ball-and-stick model of trans-1,2-dichloroethene
Ball-and-stick model of trans-1,2-dichloroethene
trans-1,2-Dichloroethene (E)
Names
Preferred IUPAC name
1,2-Dichloroethene
Other names
1,2-Dichloroethene
1,2-DCE
Acetylene dichloride
sym-Dichloroethylene
Identifiers
3D model (JSmol)
ChEBI
ChemSpider
ECHA InfoCard 100.007.956 Edit this at Wikidata
EC Number
  • 208-750-2
KEGG
UNII
  • InChI=1S/C2H2Cl2/c3-1-2-4/h1-2H checkY
    Key: KFUSEUYYWQURPO-UHFFFAOYSA-N checkY
  • InChI=1/C2H2Cl2/c3-1-2-4/h1-2H/b2-1-
    Key: KFUSEUYYWQURPO-UPHRSURJBI
  • InChI=1/C2H2Cl2/c3-1-2-4/h1-2H
    Key: KFUSEUYYWQURPO-UHFFFAOYAW
  • Cl[C@H]=CCl
  • ClC=CCl
Properties
C2H2Cl2
Molar mass 96.94 g·mol−1
Appearance colorless liquid
Odor sweet[1]
Density Z: 1.28 g/cm3
E: 1.26 g/cm3
Melting point Z: −81.47 °C
E: −49.44 °C
Boiling point Z: 60.2 °C
E: 48.5 °C
  • −51.0·10−6 cm3/mol (cis)
  • −48.9·10−6 cm3/mol (trans)
Z: 1.9 D
E: 0 D
Hazards
Flash point 2–4 Â°C; 36–39 Â°F; 275–277 K
Explosive limits 5.6–12.8%[2]
Lethal dose or concentration (LD, LC):
770 mg/kg (oral, rat)
1275 mg/kg (oral, rat, trans-isomer)[3]
21,273 ppm (mouse, 6 hr, trans-isomer)[3]
16,000 ppm (rat, 6 hr, cis-isomer)[3]
NIOSH (US health exposure limits):
PEL (Permissible)
 TWA 200 ppm (790 mg/m3)[2]
REL (Recommended)
 TWA 200 ppm (790 mg/m3)[2]
IDLH (Immediate danger)
 1000 ppm[2]
Except where otherwise noted, data are given for materials in their standard state (at 25 Â°C [77 Â°F], 100 kPa).
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Production, uses and reactions

cis-DCE, the Z isomer, is obtainable by the controlled chlorination of acetylene:

C2H2 + Cl2 → C2H2Cl2

Industrially both isomers arise as byproducts of the production of vinyl chloride, which is produced on a vast scale. Unlike 1,1-dichloroethylene, the 1,2-dichloroethylene isomers do not polymerize.[1]

trans-1,2-DCE has applications including electronics cleaning, precision cleaning, and certain metal cleaning applications.[5]

Both isomers participate in Kumada coupling reactions. trans-1,2-Dichloroethylene participates in cycloaddition reactions.[6]

Safety and environmental concerns

These compounds have "moderate oral toxicity to rats".[1]

The dichloroethylene isomers occur in some polluted waters and soils, as the decomposition products of trichloroethylene. Significant attention has been paid to their further degradation, e.g. by iron particles.[7][8]

See also

References

External links

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