Article · Wikipedia archive · Last revised Jul 18, 2026

Thiirane

Thiirane, more commonly known as ethylene sulfide, is the cyclic chemical compound with the formula C2H4S. It is the smallest sulfur-containing heterocycle and the simplest episulfide. Like many organosulfur compounds, this species has a highly unpleasant odour. Thiirane is also used to describe any derivative of the parent ethylene sulfide.

Last revised
Jul 18, 2026
Read time
≈ 2 min
Length
525 w
Citations
8
Source
Thiirane
Skeletal formula of thiirane
Skeletal formula of thiirane source ↗
Spacefill model of thiirane
Spacefill model of thiirane source ↗
Ball-and-stick model of thiirane
Ball-and-stick model of thiirane source ↗
Names
Preferred IUPAC name
Thiirane
Systematic IUPAC name
Thiacyclopropane
Other names
2,3-Dihydrothiirene1
Ethylene sulfide1
Identifiers
3D model (JSmol)
102379
ChEBI
ChemSpider
ECHA InfoCard 100.006.359
EC Number
  • 206-993-9
1278
KEGG
MeSH ethylene+sulfide
RTECS number
  • KX3500000
UNII
UN number 1992
  • InChI=1S/C2H4S/c1-2-3-1/h1-2H2 checkY
    Key: VOVUARRWDCVURC-UHFFFAOYSA-N checkY
  • C1CS1
Properties
C2H4S
Molar mass 60.11 g·mol−1
Appearance Pale, yellow liquid
Odor Sulfurous
Density 1.01 g cm−3
Melting point −109 °C (−164 °F; 164 K)
Boiling point 56 °C; 133 °F; 329 K
Vapor pressure 28.6 kPa (at 20 °C)
Thermochemistry
51–53 kJ mol−1
−2.0126 MJ mol−1
Hazards
GHS labelling:
GHS02: Flammable GHS05: Corrosive GHS06: Toxic
Danger
H225, H301, H318, H331
P210, P261, P280, P301+P310, P305+P351+P338, P311
NFPA 704 (fire diamond)
Flash point 10 °C (50 °F; 283 K)
Related compounds
Related heterocycles
Ethylene oxide
Aziridine
Borirane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Thiirane, more commonly known as ethylene sulfide, is the cyclic chemical compound with the formula C2H4S.2 It is the smallest sulfur-containing heterocycle and the simplest episulfide. Like many organosulfur compounds, this species has a highly unpleasant odour. Thiirane is also used to describe any derivative of the parent ethylene sulfide.

Structure and properties

According to electron diffraction, the C-C and C-S distances in ethylene sulfide are respectively 1.473 and 1.811 Å. The C-C-S and C-S-C angles are respectively 66.0 and 48.0°.3 The microwave and infrared spectra were studied experimentally and computationally.4

Preparation and reactions

It can be prepared by the reaction of ethylene carbonate and KSCN.5 For this purpose the KSCN is first melted under vacuum to remove water.

KSCN + C2H4O2CO → KOCN + C2H4S + CO2

Ethylenesulfide adds to amines to afford 2-mercaptoethylamines,6 which are good chelating ligands.

C2H4S + R2NH → R2NCH2CH2SH

This process is often called mercaptoethylation.7

Oxidation of thiirane with periodate gives ethylene episulfoxide.

References

References

  1. "thiirane (CHEBI:30977)". Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute.
  2. Warren Chew; David N. Harpp (1993). "Recent aspects of thiirane chemistry". Journal of Sulfur Chemistry. 15 (1): 1–39. doi:10.1080/01961779308050628.
  3. Wataru Ando; Nami Choi; Norihiro Tokitoh (1996). "Thiiranes and Thiirenes: Monocyclic". Comprehensive Heterocyclic Chemistry II. Vol. 1A. pp. 173–240. doi:10.1016/B978-008096518-5.00005-8. ISBN 978-0-08-096518-5.
  4. De Vos, John; Schröder, Benjamin; Rauhut, Guntram (2023-12-05). "Comprehensive quantum chemical analysis of the (ro)vibrational spectrum of thiirane and its deuterated isotopologue". Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy. 302 123083. Bibcode:2023AcSpA.30223083D. doi:10.1016/j.saa.2023.123083. hdl:1854/LU-01HP1F40851T3MX6QGN9QBHR4E. ISSN 1386-1425. PMID 37423098.
  5. Searles, S.; Lutz, E. F.; Hays, H. R.; Mortensen, H. E. (1962). "Ethylene Sulfide". Organic Syntheses. 42: 59. doi:10.15227/orgsyn.042.0059.
  6. R. J. Cremlyn "An Introduction to Organosulfur Chemistry" John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4.
  7. Gunars Zelans; Jacquelyn Gervay-Hague; Ivy Maulie (2010). "Ethylene Sulfide". Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons. doi:10.1002/047084289X.re079.pub2. ISBN 978-0-471-93623-7.