Chemistry:Episulfide
In organic chemistry, an episulfide (also known as a thiirane, olefin sulfide, thioalkylene oxide,[citation needed] or thiacyclopropane[citation needed]) is an organic compound that contains a saturated, heterocyclic ring consisting of two carbon atoms and one sulfur atom. It is the sulfur analogue of an epoxide or aziridine. Episulfides are less common and generally less stable than epoxides. The most common derivative is ethylene sulfide (C
2H
4S).[1][2]
Structure
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°.[1]
Preparation
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.[3]
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Episulfides can also be prepared from cyclic carbonates, hydroxyalkylthiols, halohydrins, dihaloalkanes, and chloroalkylthiols.[3] For example, the reaction of ethylene carbonate and KSCN gives ethylene sulfide:[4]
- KSCN + C
2H
4O
2CO → KOCN + C
2H
4S + CO
2
Base converts monothiocarbonates to episulfides:[5]
- RC
2H
3OSCO → RC
2H
3S + CO
2
The metal-catalyzed reaction of sulfur with alkenes has been demonstrated but is of little preparative value.[6] Tertiary episulfonium ions form when a trinitrophenylsulfonate thioester, or a mercaptonium trimer of the form (RS)+3, attacks an alkene. Note that the products are however still rather unstable.[7]: 453–455
Tetrasubstituted thiiranes form spontaneously from the corresponding thiocarbonyl ylide.[8]
Succinimide- or pthalimide sulfenyl chlorides react with alkenes to form α-chloro sulfenyl amides. Further reaction with lithium aluminum hydride gives the episulfide.[7]: 612
Reactions
Episulfides, due to their innate ring strain, often undergo ring-opening reactions, especially with nucleophiles.[3] For terminal episulfides, nucleophiles attack the primary carbon:
- R
2C(S)CH
2 + NuH → R
2CHCH
2SNu
Nucleophiles include hydrides, thiolates, alkoxides, amines, and carbanions.
Like ordinary thioethers, episulfides can be oxidized to sulfoxides as in the synthesis of ethylene episulfoxide:
- R
2C(S)CH
2 + H
2O
2 → R
2C(SO)CH
2 + H
2O
In a related reactivity, episulfides are easily S-alkylated. With methyl bromide, the product is the ring-opened thioether:[9]
- R
2C(S)CH
2 + R'Br → R
2C(Br)CH
2SR'
Such reactions proceed via episulfonium ions. Episulfonium salts can be prepared using trimethyloxonium tetrafluoroborate:
- R
2C(S)CH
2 + (CH
3)
3OBF
4 → [R
2C(SCH
3)CH
2]BF
4 + (CH
3)
2O
Episulfide polymerize, especially in the presence of Lewis acids.[10]
Applications
Thiiranes occur rarely in nature but are found in some pharmaceuticals.[1]
They are intermediate in the action of sulfur mustards, a family of chemical weapons.[12]
Related compounds
Dithiiranes consist of three-membered ring containing two sulfur atoms and one carbon. One example was prepared by oxidation of a 1,3-dithietane.[13]
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Thiirenes are unsaturated episulfides, the parent having the formula C
2H
2S formally derived by the formal addition of sulfur atom to an alkyne. They are antiaromatic and rarely observed. S-Alkylthiirenium salts are, however, known.[14][15]
References
- ↑ 1.0 1.1 1.2 Wataru Ando; Nami Choi; Norihiro Tokitoh (1996). "Thiiranes and Thiirenes: Monocyclic". Comprehensive Heterocyclic Chemistry II. 1A. pp. 173–240. doi:10.1016/B978-008096518-5.00005-8. ISBN 978-0-08-096518-5.
- ↑ Warren Chew; David N. Harpp (1993). "Recent aspects of thiirane chemistry". Journal of Sulfur Chemistry 15 (1): 1–39. doi:10.1080/01961779308050628.
- ↑ 3.0 3.1 3.2 Sander, M. Thiiranes. Chem. Rev. 1966, 66(3), 297-339. doi:10.1021/cr60241a004
- ↑ Searles, S.; Lutz, E. F.; Hays, H. R.; Mortensen, H. E. (1962). "Ethylene Sulfide". Organic Syntheses 42: 59. doi:10.15227/orgsyn.042.0059.
- ↑ Reynolds, D. D.; Fields, D. L.; Johnson, D. L. (1961). "Mercaptoethylation. VII. Preparation of Some Cyclic Sulfides". The Journal of Organic Chemistry 26 (12): 5130–5133. doi:10.1021/jo01070a084.
- ↑ Adam, Waldemar; Bargon, Rainer M. (2004). "Synthesis of Thiiranes by Direct Sulfur Transfer: The Challenge of Developing Effective Sulfur Donors and Metal Catalysts". Chemical Reviews 104 (1): 251–262. doi:10.1021/cr030005p. PMID 14719976.
- ↑ 7.0 7.1 Zoller, Uri (1983). "Three-membered rings containing sulfur". in Hassner, Alfred. Small Ring Heterocycles, Part 1. The Chemistry of Heterocyclic Compounds. 42. Interscience. doi:10.1002/9780470187180. ISBN 978-0-471-05626-3.
- ↑ Rolf Huisgen; J. Rapp (1997). "1,3-Dipolar Cycloadditions. 98. The Chemistry of Thiocarbonyl S-Sulfides". Tetrahedron 53 (3): 950. doi:10.1016/S0040-4020(96)01068-X.
- ↑ Dittmer, D.C. (1984). "Thiiranes and Thiirenes". Comprehensive Heterocyclic Chemistry. pp. 131–184. doi:10.1016/B978-008096519-2.00112-0. ISBN 978-0-08-096519-2.
- ↑ Nakano, K.; Tatsumi, G.; Nazaki, K. (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. 129 (49): 15116–15117. doi:10.1021/ja076056b. PMID 17999507. Bibcode: 2007JAChS.12915116N.
- ↑ The Dictionary of Drugs: Chemical Data: Chemical Data, Structures and Bibliographies. Springer. 14 November 2014. pp. 492–. ISBN 978-1-4757-2085-3. https://books.google.com/books?id=0vXTBwAAQBAJ&pg=PA492.
- ↑ 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.
- ↑ 13.0 13.1 Ahhiko Ishii; Masamatsu Hoshino; Juzo Nakayama (2009). "Recent Advances in Chemistry of Dithiirane and Small Ring Compounds Containing Two Chalcogen Atoms". Pure Appl. Chem. 68 (4): 869–874. doi:10.1351/pac199668040869.
- ↑ Vilaivan, T.; Chavasiri, W.; Rashatasakhon, P. (2008). "Thiiranes and Thiirenes: Fused-ring Derivatives". Comprehensive Heterocyclic Chemistry III. pp. 391–431. doi:10.1016/B978-008044992-0.00106-1. ISBN 978-0-08-044992-0.
- ↑ Poleschner, Helmut; Seppelt, Konrad (2013). "XeF2/Fluoride Acceptors as Versatile One-Electron Oxidants". Angewandte Chemie International Edition 52 (49): 12838–12842. doi:10.1002/anie.201307161. PMID 24127390.
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