organic chemistry Organic chemistry is a subdiscipline within chemistry involving the science, scientific study of the structure, properties, and reactions of organic compounds and organic matter, organic materials, i.e., matter in its various forms that contain ...

, an episulfide is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

that contain a

saturated Saturation, saturated, unsaturation or unsaturated may refer to: Chemistry *Saturated and unsaturated compounds, a classification of compounds related to their ability to resist addition reactions **Degree of unsaturation **Saturated fat or satur ...

heterocyclic ring A heterocyclic compound or ring structure is a cyclic compound that has atoms of at least two different elements as members of its ring(s). Heterocyclic organic chemistry is the branch of organic chemistry dealing with the synthesis, proper ...

consisting of two

carbon Carbon () is a chemical element; it has chemical symbol, symbol C and atomic number 6. It is nonmetallic and tetravalence, tetravalent—meaning that its atoms are able to form up to four covalent bonds due to its valence shell exhibiting 4 ...

atoms and one

sulfur Sulfur ( American spelling and the preferred IUPAC name) or sulphur ( Commonwealth spelling) is a chemical element; it has symbol S and atomic number 16. It is abundant, multivalent and nonmetallic. Under normal conditions, sulfur atoms ...

atom. It is the sulfur analogue of an

epoxide In organic chemistry, an epoxide is a cyclic ether, where the ether forms a three-atom ring: two atoms of carbon and one atom of oxygen. This triangular structure has substantial ring strain, making epoxides highly reactive, more so than other ...

aziridine Aziridine is an organic compound consisting of the three-membered heterocycle . It is a colorless, toxic, volatile liquid that is of significant practical interest. Aziridine was discovered in 1888 by the chemist Siegmund Gabriel. Its deriva ...

. They are also known as thiiranes, olefin sulfides, thioalkylene oxides, and thiacyclopropanes. Episulfides are less common and generally less stable than epoxides. The most common derivative is

ethylene sulfide 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 ...

().

Structure

According to

electron diffraction Electron diffraction is a generic term for phenomena associated with changes in the direction of electron beams due to elastic interactions with atoms. It occurs due to elastic scattering, when there is no change in the energy of the electrons. ...

, the and distances in ethylene sulfide are respectively 1.473 and 1.811 Å. The and angles are respectively 66.0 and 48.0°.

Preparation

History

A number of chemists in the early 1900s, including Staudinger and Pfenninger (1916), as well as Delepine (1920) studied episulfides.Sander, M. Thiiranes. Chem. Rev. 1966, 66(3), 297-339. In 1934 Dachlauer and Jackel devised a general synthesis of episulfides from epoxides using alkali thiocyanates and thiourea.

Contemporary methods

Following the lead of Dachlauer and Jackel, contemporary routes to episulfides utilize a two-step method, converting an olefin to an epoxide followed by thiation using

thiocyanate Thiocyanates are salts containing the thiocyanate anion (also known as rhodanide or rhodanate). is the conjugate base of thiocyanic acid. Common salts include the colourless salts potassium thiocyanate and sodium thiocyanate. Mercury(II) t ...

thiourea Thiourea () is an organosulfur compound with the formula and the structure . It is structurally similar to urea (), with the oxygen atom replaced by sulfur atom (as implied by the '' thio-'' prefix). The properties of urea and thiourea differ s ...

. : Episulfides can also be prepared from cyclic carbonates, hydroxy mercaptans, hydroxyalkyl halides, dihaloalkanes, and halo mercaptans. The reaction of

ethylene carbonate Ethylene carbonate (sometimes abbreviated EC) is the organic compound with the formula (CH2O)2CO. It is classified as the cyclic carbonate ester of ethylene glycol and carbonic acid. At room temperature (25 °C) ethylene carbonate is a tra ...

and KSCN gives

: :KSCN + C2H4O2CO -> KOCN + C2H4S + CO2 The metal-catalyzed reaction of sulfur with alkenes has been demonstrated. :

\text + \text \longrightarrow  \text

Reactions

Common uses of episulfides in both academic and industrial settings most often involve their use as monomers in polymerization reactions. Episulfides have an innate ring strain due to the nature of three-membered rings. Therefore, most reactions of episulfides involve ring-opening. Most commonly, nucleophiles are employed for the ring-opening process. For terminal episulfide, nucleophiles attack the primary carbon. Nucleophiles include hydrides, thiolates, alkoxides, amines, and carbanions. :

Applications

Thiiranes occur very rarely in nature and are of no significance medicinally. Very few commercial applications exist, although the polymerization of episulfide has been reported.

Dithiirane

Dithiirane is three membered ring containing two sulfur atoms and one carbon. One example was prepared by oxidation of a 1,3-

dithietane A dithietane is a saturated heterocyclic compound that contain two Valence (chemistry), divalent sulfur atoms and two Orbital hybridisation, sp3-hybridized carbon atoms. Two isomers are possible for this class of organosulfur compounds: 1,2-Dith ...

References

{{reflist Functional groups