In organic chemistry, episulfides are a class of organic compounds that contain a saturated, heterocyclic ring consisting of two carbon atoms and one sulfur atom. It is the sulfur analogue of an epoxide or aziridine. 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 (C2H4S). [1] [2]
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]
A number of chemists in the early 1900s, including Staudinger and Pfenninger (1916), as well as Delepine (1920) studied episulfides. [3] In 1934 Dachlauer and Jackel devised a general synthesis of episulfides from epoxides using alkali thiocyanates and thiourea.
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. [3]
Episulfides can also be prepared from cyclic carbonates, hydroxy mercaptans, hydroxyalkyl halides, dihaloalkanes, and halo mercaptans. [3] The reaction of ethylene carbonate and KSCN gives ethylene sulfide: [4]
The metal-catalyzed reaction of sulfur with alkenes has been demonstrated. [5]
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. [3] For terminal episulfide, nucleophiles attack the primary carbon. Nucleophiles include hydrides, thiolates, alkoxides, amines, and carbanions.
Thiiranes occur very rarely in nature and are of no significance medicinally. [1]
Very few commercial applications exist, although the polymerization of episulfide has been reported. [6]
Dithiiranes are three membered rings containing two sulfur atoms and one carbon. One example was prepared by oxidation of a 1,3-dithietane. [7]
In organic chemistry, an alkene, or olefin, is a hydrocarbon containing a carbon–carbon double bond. The double bond may be internal or in the terminal position. Terminal alkenes are also known as α-olefins.
In chemistry, an ester is a compound derived from an acid in which the hydrogen atom (H) of at least one acidic hydroxyl group of that acid is replaced by an organyl group. These compounds contain a distinctive functional group. Analogues derived from oxygen replaced by other chalcogens belong to the ester category as well. According to some authors, organyl derivatives of acidic hydrogen of other acids are esters as well, but not according to the IUPAC.
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 ethers. They are produced on a large scale for many applications. In general, low molecular weight epoxides are colourless and nonpolar, and often volatile.
In chemistry, an electrophile is a chemical species that forms bonds with nucleophiles by accepting an electron pair. Because electrophiles accept electrons, they are Lewis acids. Most electrophiles are positively charged, have an atom that carries a partial positive charge, or have an atom that does not have an octet of electrons.
Thiophene is a heterocyclic compound with the formula C4H4S. Consisting of a planar five-membered ring, it is aromatic as indicated by its extensive substitution reactions. It is a colorless liquid with a benzene-like odor. In most of its reactions, it resembles benzene. Compounds analogous to thiophene include furan (C4H4O), selenophene (C4H4Se) and pyrrole (C4H4NH), which each vary by the heteroatom in the ring.
In organic chemistry, a carbene is a molecule containing a neutral carbon atom with a valence of two and two unshared valence electrons. The general formula is R−:C−R' or R=C: where the R represents substituents or hydrogen atoms.
Polysulfides are a class of chemical compounds derived from anionic chains of sulfur atoms. There are two main classes of polysulfides: inorganic and organic. The inorganic polysulfides have the general formula S2−
n. These anions are the conjugate bases of polysulfanes H2Sn. Organic polysulfides generally have the formulae R1SnR2, where R is an alkyl or aryl group.
Thiourea is an organosulfur compound with the formula SC(NH2)2 and the structure H2N−C(=S)−NH2. It is structurally similar to urea, except that the oxygen atom is replaced by a sulfur atom ; however, the properties of urea and thiourea differ significantly. Thiourea is a reagent in organic synthesis. Thioureas are a broad class of compounds with the general structure R2N−C(=S)−NR2.
In organic chemistry, the Michael reaction or Michael 1,4 addition is a reaction between a Michael donor and a Michael acceptor to produce a Michael adduct by creating a carbon-carbon bond at the acceptor's β-carbon. It belongs to the larger class of conjugate additions and is widely used for the mild formation of carbon-carbon bonds.
In organic chemistry, olefin metathesis is an organic reaction that entails the redistribution of fragments of alkenes (olefins) by the scission and regeneration of carbon-carbon double bonds. Because of the relative simplicity of olefin metathesis, it often creates fewer undesired by-products and hazardous wastes than alternative organic reactions. For their elucidation of the reaction mechanism and their discovery of a variety of highly active catalysts, Yves Chauvin, Robert H. Grubbs, and Richard R. Schrock were collectively awarded the 2005 Nobel Prize in Chemistry.
Ring-closing metathesis (RCM) is a widely used variation of olefin metathesis in organic chemistry for the synthesis of various unsaturated rings via the intramolecular metathesis of two terminal alkenes, which forms the cycloalkene as the E- or Z- isomers and volatile ethylene.
A halonium ion is any onium ion containing a halogen atom carrying a positive charge. This cation has the general structure R−−R′ where X is any halogen and no restrictions on R, this structure can be cyclic or an open chain molecular structure. Halonium ions formed from fluorine, chlorine, bromine, and iodine are called fluoronium, chloronium, bromonium, and iodonium, respectively. The 3-membered cyclic variety commonly proposed as intermediates in electrophilic halogenation may be called haliranium ions, using the Hantzsch-Widman nomenclature system.
The Ramberg–Bäcklund reaction is an organic reaction converting an α-halo sulfone into an alkene in presence of a base with extrusion of sulfur dioxide. The reaction is named after the two Swedish chemists Ludwig Ramberg and Birger Bäcklund. The carbanion formed by deprotonation gives an unstable episulfone that decomposes with elimination of sulfur dioxide. This elimination step is considered to be a concerted cheletropic extrusion.
Potassium thiocyanate is the chemical compound with the molecular formula KSCN. It is an important salt of the thiocyanate anion, one of the pseudohalides. The compound has a low melting point relative to most other inorganic salts.
In organic chemistry, aziridines are organic compounds containing the aziridine functional group, a three-membered heterocycle with one amine and two methylene bridges. The parent compound is aziridine, with molecular formula C2H4NH. Several drugs feature aziridine rings, including mitomycin C, porfiromycin, and azinomycin B (carzinophilin).
The Boord olefin synthesis is an organic reaction forming alkenes from ethers carrying a halogen atom 2 carbons removed from the oxygen atom (β-halo-ethers) using a metal such as magnesium or zinc. The reaction, discovered by Cecil E. Boord in 1930 is a classic named reaction with high yields and broad scope.
In organometallic chemistry, a migratory insertion is a type of reaction wherein two ligands on a metal complex combine. It is a subset of reactions that very closely resembles the insertion reactions, and both are differentiated by the mechanism that leads to the resulting stereochemistry of the products. However, often the two are used interchangeably because the mechanism is sometimes unknown. Therefore, migratory insertion reactions or insertion reactions, for short, are defined not by the mechanism but by the overall regiochemistry wherein one chemical entity interposes itself into an existing bond of typically a second chemical entity e.g.:
Thietane is a heterocyclic compound containing a saturated four-membered ring with three carbon atoms and one sulfur atom.
An oxaziridine is an organic molecule that features a three-membered heterocycle containing oxygen, nitrogen, and carbon. In their largest application, oxaziridines are intermediates in the industrial production of hydrazine. Oxaziridine derivatives are also used as specialized reagents in organic chemistry for a variety of oxidations, including alpha hydroxylation of enolates, epoxidation and aziridination of olefins, and other heteroatom transfer reactions. Oxaziridines also serve as precursors to nitrones and participate in [3+2] cycloadditions with various heterocumulenes to form substituted five-membered heterocycles. Chiral oxaziridine derivatives effect asymmetric oxygen transfer to prochiral enolates as well as other substrates. Some oxaziridines also have the property of a high barrier to inversion of the nitrogen, allowing for the possibility of chirality at the nitrogen center.
An N-heterocyclic olefin (NHO) is a neutral heterocyclic compound with a highly polarized, electron-rich C=C olefin attached to a heterocycle made up of two nitrogen atoms. A derivative of N-heterocyclic carbenes (NHCs), NHO was first synthesized in 1961 by Horst Böhme and Fritz Soldan, but the term NHO was not used until 2011 by Eric Rivard and coworkers. Since its discovery, NHOs have been applied in organocatalysis, metal ligation, and polymerization.
