Episulfide

Structure

According to electron diffraction, 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. 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 or thiourea.

:[[Image:episulfide pic2.png|450px]]

Episulfides can also be prepared from cyclic carbonates, hydroxy mercaptans, hydroxyalkyl halides, dihaloalkanes, and halo mercaptans. For example, the reaction of ethylene carbonate and KSCN gives ethylene sulfide: :KSCN + C2H4O2CO - KOCN + C2H4S + CO2

The metal-catalyzed reaction of sulfur with alkenes has been demonstrated. :\text{alkene} + \text{S } \longrightarrow \text{ episulfide}

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.

:[[Image:episulfide pic4.png|450px]]

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.

References

References

1. Wataru Ando. (1996). "Thiiranes and Thiirenes: Monocyclic".
2. Sander, M. Thiiranes. Chem. Rev. 1966, 66(3), 297-339. {{doi. 10.1021/cr60241a004
3. (1962). "Ethylene Sulfide". Organic Syntheses.
4. (2004). "Synthesis of Thiiranes by Direct Sulfur Transfer: The Challenge of Developing Effective Sulfur Donors and Metal Catalysts". Chemical Reviews.
5. They are intermediate in the action of [[sulfur mustard]]s, a family of [[chemical weapon]]s.[http://www.opcw.org/about-chemical-weapons/types-of-chemical-agent/mustard-agents/ Mustard agents: description, physical and chemical properties, mechanism of action, symptoms, antidotes and methods of treatment]. Organisation for the Prohibition of Chemical Weapons. Accessed June 8, 2010.
6. (2007). "Synthesis of Sulfur-Rich Polymers: Copolymerization of Episulfide with Carbon Disulfide by Using [PPN]Cl/(salph)Cr(III)Cl System". J. Am. Chem. Soc..
7. Ahhiko Ishii. (2009). "Recent Advances in Chemistry of Dithiirane and Small Ring Compounds Containing Two Chalcogen Atoms". Pure Appl. Chem..