1,2-Dichloroethene, commonly called 1,2-dichloroethylene or 1,2-DCE, is an organochloride with the molecular formula C2H2Cl2. It is a highly flammable, colorless liquid with a sharp, harsh 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 few industrial applications,[3] although they are fundamental given their simple stoichiometries.

Skeletal formula of cis-1,2-dichloroethene
Skeletal formula of trans-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
trans-1,2-Dichloroethene (E)
Preferred IUPAC name
Other names
  • 156-59-2 (Z) checkY
  • 156-60-5 (E) checkY
  • 540-59-0 (E/Z) checkY
3D model (JSmol)
ECHA InfoCard 100.007.956 Edit this at Wikidata
  • InChI=1S/C2H2Cl2/c3-1-2-4/h1-2H checkY
  • InChI=1/C2H2Cl2/c3-1-2-4/h1-2H/b2-1-
  • InChI=1/C2H2Cl2/c3-1-2-4/h1-2H
  • Cl[C@H]=CCl
  • ClC=CCl
Molar mass 96.95 g/mol
Appearance clear liquid[1]
Odor acrid, chloroform-like[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
Flash point 2–4 °C; 36–39 °F; 275–277 K
Explosive limits 5.6–12.8%[1]
Lethal dose or concentration (LD, LC):
770 mg/kg (oral, rat)
1275 mg/kg (oral, rat, trans-isomer)[2]
21,273 ppm (mouse, 6 hr, trans-isomer)[2]
16,000 ppm (rat, 6 hr, cis-isomer)[2]
NIOSH (US health exposure limits):
PEL (Permissible)
TWA 200 ppm (790 mg/m3)[1]
REL (Recommended)
TWA 200 ppm (790 mg/m3)[1]
IDLH (Immediate danger)
1000 ppm[1]
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references


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

C2H2 + Cl2 → C2H2Cl2

Industrially both isomers arise as byproduct of the production of vinyl chloride, which is produced on a vast scale. Unlike vinyl chloride, the 1,2-dichloroethylene isomers do not polymerize.[3]

trans-DCE has applications including electronics cleaning, precision cleaning, and certain metal cleaning applications.[4]

E-Z relative stabilityEdit

In contrast to most cis-trans compounds, the Z isomer (cis) is more stable than the E isomer (trans) by 0.4 kcal/mol.[5]


These compounds have "moderate oral toxicity to rats".[3]

See alsoEdit


  1. ^ a b c d e f g NIOSH Pocket Guide to Chemical Hazards. "#0195". National Institute for Occupational Safety and Health (NIOSH).
  2. ^ a b c "1,2-Dichloroethylene". Immediately Dangerous to Life or Health Concentrations (IDLH). National Institute for Occupational Safety and Health (NIOSH).
  3. ^ a b c E.-L. Dreher; T. R. Torkelson; K. K. Beutel (2011). "Chlorethanes and Chloroethylenes". Ullmann's Encyclopedia of Industrial Chemistry. Weinheim: Wiley-VCH. doi:10.1002/14356007.o06_o01. ISBN 978-3527306732.
  4. ^ "Chlorinated Solvents and Feed Stock - Axiall". Archived from the original on 2016-04-08. Retrieved 2016-03-23.
  5. ^ Pitzer, Kenneth S.; Hollenberg, J. L. (1954). "cis- and trans-Dichloroethylenes. The Infrared Spectra from 130–400 Cm.–1 and the Thermodynamic Properties". J. Am. Chem. Soc. 76 (6): 1493–1496. doi:10.1021/ja01635a010.

External linksEdit