Organic sulfide

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General structure of a sulfide with the blue marked functional group. FunktionelleGruppen Thioether.svg
General structure of a sulfide with the blue marked functional group.

In organic chemistry, a sulfide (British English sulphide) or thioether is an organosulfur functional group with the connectivity R−S−R' as shown on right. Like many other sulfur-containing compounds, volatile sulfides have foul odors. [1] A sulfide is similar to an ether except that it contains a sulfur atom in place of the oxygen. The grouping of oxygen and sulfur in the periodic table suggests that the chemical properties of ethers and sulfides are somewhat similar, though the extent to which this is true in practice varies depending on the application.

Contents

Nomenclature

Sulfides are sometimes called thioethers, especially in the old literature. The two organic substituents are indicated by the prefixes. (CH3)2S is called dimethylsulfide. Some sulfides are named by modifying the common name for the corresponding ether. For example, C6H5SCH3 is methyl phenyl sulfide, but is more commonly called thioanisole, since its structure is related to that for anisole, C6H5OCH3.

The modern systematic nomenclature in chemistry for the trival name thioether is sulfane. [2]

Structure and properties

Sulfide is an angular functional group, the C–S–C angle approaching 90° The C–S bonds are about 180  pm. For the prototype, dimethylsulfide, the C-S-C angles is 99°, which is smaller than the C-O-C angle in ether (~110°). The C-S distance in dimethylsulfide is 1.81 Å. [3]

Sulfides are characterized by their strong odors, which are similar to thiol odor. This odor limits the applications of volatile sulfides. In terms of their physical properties they resemble ethers, but are less volatile, higher melting, and less hydrophilic. These properties follow from the polarizability of the divalent sulfur center, which is greater than that for oxygen in ethers.

Thiophenes

Thiophenes are a special class of sulfide-containing heterocyclic compounds. Because of their aromatic character, they are non-nucleophilic. The nonbonding electrons on sulfur are delocalized into the π-system. As a consequence, thiophene exhibits few properties expected for a sulfide – thiophene is non-nucleophilic at sulfur and, in fact, is sweet-smelling. Upon hydrogenation, thiophene gives tetrahydrothiophene, C4H8S, which indeed does behave as a typical sulfide.

Occurrence and applications

Sulfides are important in biology, notably in the amino acid methionine and the cofactor biotin. Petroleum contains many organosulfur compounds, including sulfides. Polyphenylene sulfide is a useful high temperature plastic. Coenzyme M, CH
3SCH
2CH
2SO−
3, is the precursor to methane (i.e. natural gas) via the process of methanogenesis.

Selected thioethers, from left: dimethylsulfide, coenzyme-M, the amino acid methionine, the vitamin biotin, and the engineering plastic polyphenylene sulfide. ThioetherGallery.png
Selected thioethers, from left: dimethylsulfide, coenzyme-M, the amino acid methionine, the vitamin biotin, and the engineering plastic polyphenylene sulfide.

Preparation

Sulfides are typically prepared by alkylation of thiols. Alkylating agents include not only alkyl halides, but also epoxides, aziridines, and Michael acceptors. [4]

RBr + HSR' → RSR' + HBr

Such reactions are usually conducted in the presence of a base, which converts the thiol into the more nucleophilic thiolate. [5] Analogously, the reaction of disulfides with organolithium reagents produces thioethers:

R3CLi + R1S-SR2 → R3CSR1 + R2SLi

Analogous reactions are known starting with Grignard reagents.

Alternatively, sulfides can be synthesized by the addition of a thiol to an alkene in the thiol-ene reaction:

R-CH=CH2 + H-SR' → R-CH2-CH2-S-R'

This reaction is often catalysed by free radicals produced from a photoinitiator. [6]

Sulfides can also be prepared by many other methods, such as the Pummerer rearrangement. Trialkysulfonium salts react with nucleophiles with a dialkyl sulfide as a leaving group:

Nu− + R3S+ → Nu-R + R2SR1

This reaction is exploited in biological systems as a means of transferring an alkyl group. For example, S-adenosylmethionine acts as a methylating agent in biological SN2 reactions.

An unusual but well tested method for the synthesis of thioethers involves addition of alkenes, especially ethylene across the S-Cl bond of sulfur dichloride. This method has been used in the production of bis(2-chloroethyl)sulfide, a mustard gas: [7]

SCl2 + 2 C2H4 → (ClC2H4)2S

Reactions

The Lewis basic lone pairs on sulfur dominate the sulfides' reactivity. Sulfides readily alkylate to stable sulfonium salts, such as trimethylsulfonium iodide: [8]

S(CH3)2 + CH3I → [S(CH3)3]+I−

Sulfides also oxidize easily to sulfoxides (R−S(=O)−R), which can themselves be further oxidized to sulfones (R−S(=O)2−R). Hydrogen peroxide is a typical oxidant—for example, with dimethyl sulfide (S(CH3)2): [9]

S(CH3)2 + H2O2 → OS(CH3)2 + H2O
OS(CH3)2 + H2O2 → O2S(CH3)2 + H2O

In analogy to their easy alkylation, sulfides bind to metals to form thioether complexes. Consequently Lewis acids do not decompose thioethers as they do ethers. [10] Sulfides are soft ligands, but their affinity for metals is lower than typical phosphines. Chelating thioethers are known, such as 1,4,7-trithiacyclononane.

Sulfides undergo hydrogenolysis in the presence of certain metals:

R-S-R' + 2 H2 → RH + R'H + H2S

Raney nickel is useful for stoichiometric reactions in organic synthesis [11] whereas molybdenum-based catalysts are used to "sweeten" petroleum fractions, in the process called hydrodesulfurization.[ citation needed ] Similarly dissolving metal reductions can induce dealkylation or dearylation. [12]

Unlike ethers, thioethers are stable in the presence of Grignard reagents. [13] The protons adjacent to the sulfur atom are labile, and can be deprotonated with strong bases. [14]

Related Research Articles

<span class="mw-page-title-main">Ether</span> Organic compounds made of alkyl/aryl groups bound to oxygen (R–O–R)

In organic chemistry, ethers are a class of compounds that contain an ether group—an oxygen atom bonded to two organyl groups. They have the general formula R−O−R′, where R and R′ represent the organyl groups. Ethers can again be classified into two varieties: if the organyl groups are the same on both sides of the oxygen atom, then it is a simple or symmetrical ether, whereas if they are different, the ethers are called mixed or unsymmetrical ethers. A typical example of the first group is the solvent and anaesthetic diethyl ether, commonly referred to simply as "ether". Ethers are common in organic chemistry and even more prevalent in biochemistry, as they are common linkages in carbohydrates and lignin.

<span class="mw-page-title-main">Ester</span> Compound derived from an acid

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.

<span class="mw-page-title-main">Thiol</span> Any organic compound having a sulfanyl group (–SH)

In organic chemistry, a thiol, or thiol derivative, is any organosulfur compound of the form R−SH, where R represents an alkyl or other organic substituent. The −SH functional group itself is referred to as either a thiol group or a sulfhydryl group, or a sulfanyl group. Thiols are the sulfur analogue of alcohols, and the word is a blend of "thio-" with "alcohol".

<span class="mw-page-title-main">Thioester</span> Organosulfur compounds of the form R–SC(=O)–R’

In organic chemistry, thioesters are organosulfur compounds with the molecular structure R−C(=O)−S−R’. They are analogous to carboxylate esters with the sulfur in the thioester replacing oxygen in the carboxylate ester, as implied by the thio- prefix. They are the product of esterification of a carboxylic acid with a thiol. In biochemistry, the best-known thioesters are derivatives of coenzyme A, e.g., acetyl-CoA. The R and R' represent organyl groups, or H in the case of R.

<span class="mw-page-title-main">Alkylation</span> Transfer of an alkyl group from one molecule to another

Alkylation is a chemical reaction that entails transfer of an alkyl group. The alkyl group may be transferred as an alkyl carbocation, a free radical, a carbanion, or a carbene. Alkylating agents are reagents for effecting alkylation. Alkyl groups can also be removed in a process known as dealkylation. Alkylating agents are often classified according to their nucleophilic or electrophilic character. In oil refining contexts, alkylation refers to a particular alkylation of isobutane with olefins. For upgrading of petroleum, alkylation produces a premium blending stock for gasoline. In medicine, alkylation of DNA is used in chemotherapy to damage the DNA of cancer cells. Alkylation is accomplished with the class of drugs called alkylating antineoplastic agents.

In organic chemistry, a nitrile is any organic compound that has a −C≡N functional group. The name of the compound is composed of a base, which includes the carbon of the −C≡N, suffixed with "nitrile", so for example CH3CH2C≡N is called "propionitrile". The prefix cyano- is used interchangeably with the term nitrile in industrial literature. Nitriles are found in many useful compounds, including methyl cyanoacrylate, used in super glue, and nitrile rubber, a nitrile-containing polymer used in latex-free laboratory and medical gloves. Nitrile rubber is also widely used as automotive and other seals since it is resistant to fuels and oils. Organic compounds containing multiple nitrile groups are known as cyanocarbons.

The prefix thio-, when applied to a chemical, such as an ion, means that an oxygen atom in the compound has been replaced by a sulfur atom. This term is often used in organic chemistry. For example, from the word ether, referring to an oxygen-containing compound having the general chemical structure R−O−R′, where R and R′ are organic functional groups and O is an oxygen atom, comes the word thioether, which refers to an analogous compound with the general structure R−S−R′, where S is a sulfur atom covalently bonded to two organic groups. A chemical reaction involving the replacement of oxygen to sulfur is called thionation or thiation.

<span class="mw-page-title-main">Sulfonic acid</span> Organic compounds with the structure R−S(=O)2−OH

In organic chemistry, sulfonic acid refers to a member of the class of organosulfur compounds with the general formula R−S(=O)2−OH, where R is an organic alkyl or aryl group and the S(=O)2(OH) group a sulfonyl hydroxide. As a substituent, it is known as a sulfo group. A sulfonic acid can be thought of as sulfuric acid with one hydroxyl group replaced by an organic substituent. The parent compound is the parent sulfonic acid, HS(=O)2(OH), a tautomer of sulfurous acid, S(=O)(OH)2. Salts or esters of sulfonic acids are called sulfonates.

<span class="mw-page-title-main">Triphenylphosphine</span> Chemical compound

Triphenylphosphine (IUPAC name: triphenylphosphane) is a common organophosphorus compound with the formula P(C6H5)3 and often abbreviated to PPh3 or Ph3P. It is versatile compound that is widely used as a reagent in organic synthesis and as a ligand for transition metal complexes, including ones that serve as catalysts in organometallic chemistry. PPh3 exists as relatively air stable, colorless crystals at room temperature. It dissolves in non-polar organic solvents such as benzene and diethyl ether.

Organosulfur chemistry is the study of the properties and synthesis of organosulfur compounds, which are organic compounds that contain sulfur. They are often associated with foul odors, but many of the sweetest compounds known are organosulfur derivatives, e.g., saccharin. Nature is abound with organosulfur compounds—sulfur is vital for life. Of the 20 common amino acids, two are organosulfur compounds, and the antibiotics penicillin and sulfa drugs both contain sulfur. While sulfur-containing antibiotics save many lives, sulfur mustard is a deadly chemical warfare agent. Fossil fuels, coal, petroleum, and natural gas, which are derived from ancient organisms, necessarily contain organosulfur compounds, the removal of which is a major focus of oil refineries.

<span class="mw-page-title-main">Xanthate</span> Salt that is a metal-thioate/O-esters of dithiocarbonate

A xanthate is a salt or ester of a xanthic acid. The formula of the salt of xanthic acid is [R−O−CS2]−M+. Xanthate also refers to the anion [R−O−CS2]−. The formula of a xanthic acid is R−O−C(=S)−S−H, such as ethyl xanthic acid, while the formula of an ester of a xanthic acid is R−O−C(=S)−S−R', where R and R' are organyl groups. The salts of xanthates are also called O-organyl dithioates. The esters of xanthic acid are also called O,S-diorganyl esters of dithiocarbonic acid. The name xanthate is derived from Ancient Greek ξανθός (xanthos) meaning 'yellowish' or 'golden', and indeed most xanthate salts are yellow. They were discovered and named in 1823 by Danish chemist William Christopher Zeise. These organosulfur compounds are important in two areas: the production of cellophane and related polymers from cellulose and for extraction of certain sulphide bearing ores. They are also versatile intermediates in organic synthesis.

<span class="mw-page-title-main">Dimethyl sulfide</span> Chemical compound

Dimethyl sulfide (DMS) or methylthiomethane is an organosulfur compound with the formula (CH3)2S. It is the simplest thioether and has a characteristic disagreeable odor. It is a flammable liquid that boils at 37 °C (99 °F). It is a component of the smell produced from cooking of certain vegetables and seafoods. It is also an indication of bacterial contamination in malt production and brewing. It is a breakdown product of dimethylsulfoniopropionate (DMSP), and is also produced by the bacterial metabolism of methanethiol.

<span class="mw-page-title-main">Enol ether</span> Class of chemical compounds

In organic chemistry an enol ether is an alkene with an alkoxy substituent. The general structure is R2C=CR-OR where R = H, alkyl or aryl. A common subfamily of enol ethers are vinyl ethers, with the formula ROCH=CH2. Important enol ethers include the reagent 3,4-dihydropyran and the monomers methyl vinyl ether and ethyl vinyl ether.

Sulfur compounds are chemical compounds formed the element sulfur (S). Common oxidation states of sulfur range from −2 to +6. Sulfur forms stable compounds with all elements except the noble gases.

<span class="mw-page-title-main">Thiophenol</span> Chemical compound

Thiophenol is an organosulfur compound with the formula C6H5SH, sometimes abbreviated as PhSH. This foul-smelling colorless liquid is the simplest aromatic thiol. The chemical structures of thiophenol and its derivatives are analogous to phenols, where the oxygen atom in the hydroxyl group (-OH) bonded to the aromatic ring in phenol is replaced by a sulfur atom. The prefix thio- implies a sulfur-containing compound and when used before a root word name for a compound which would normally contain an oxygen atom, in the case of 'thiol' that the alcohol oxygen atom is replaced by a sulfur atom.

<span class="mw-page-title-main">Thioacetic acid</span> Organosulfur compound (CH3C(O)SH)

Thioacetic acid is an organosulfur compound with the molecular formula CH3C(O)SH. It is a thioic acid: the sulfur analogue of acetic acid, as implied by the thio- prefix. It is a yellow liquid with a strong thiol-like odor. It is used in organic synthesis for the introduction of thiol groups in molecules.

<span class="mw-page-title-main">Sulfenyl chloride</span> Chemical group (R–S–Cl)

In organosulfur chemistry, a sulfenyl chloride is a functional group with the connectivity R−S−Cl, where R is alkyl or aryl. Sulfenyl chlorides are reactive compounds that behave as sources of RS+. They are used in the formation of RS−N and RS−O bonds. According to IUPAC nomenclature they are named as alkyl thiohypochlorites, i.e. esters of thiohypochlorous acid.

In organic chemistry, thiocarboxylic acids or carbothioic acids are organosulfur compounds related to carboxylic acids by replacement of one of the oxygen atoms with a sulfur atom. Two tautomers are possible: a thione form and a thiol form. These are sometimes also referred to as "carbothioic O-acid" and "carbothioic S-acid" respectively. Of these the thiol form is most common.

<span class="mw-page-title-main">Sulfenamide</span> Molecules of the form >N–S–

In organosulfur chemistry, sulfenamides are a class of organosulfur compounds characterized by the general formula R−S−N(−R)2, where the R groups are hydrogen, alkyl, or aryl. Sulfenamides have been used extensively in the vulcanization of rubber using sulfur. They are related to the oxidized compounds known as sulfinamides and sulfonamides.

Divinyl sulfide is the organosulfur compound with the formula S(CH=CH2)2. A colorless liquid with a faint odor, it is found in some species of Allium.

References

  1. ↑ Cremlyn, R. J. (1996). An Introduction to Organosulfur Chemistry. Chichester: John Wiley and Sons. ISBN   0-471-95512-4.
  2. ↑ Hellwinkel, Dieter (2012-12-06). Systematic Nomenclature of Organic Chemistry: A Directory to Comprehension and Application of its Basic Principles (1 ed.). Springer Science & Business Media. p. 131. ISBN   978-3-64256765-0. p. 131: Individual species of the genus thioether can again most uniformly be named as ...sulfane and ...sulfanyl derivatives, respectively (formerly: ...sulfides and ...thio derivatives, respectively). [...] Cyclic sulfides (thioethers) are treated as heterocycles, in the same way as their ether counterparts. Polysulfides substituted at both ends are named substitutively as ...polysulfanes (formerly: ...polysulfides). (230 pages)
  3. ↑ Iijima, T.; Tsuchiy, S.; Kimura, M. (1977). "The Molecular Structure of Dimethyl Sulfide". Bull. Chem. Soc. Jpn. 50 (10): 2564. doi: 10.1246/bcsj.50.2564 .
  4. ↑ Chauhan, Pankaj; Mahajan, Suruchi; Enders, Dieter (2014). "Organocatalytic Carbon–Sulfur Bond-Forming Reactions". Chemical Reviews. 114 (18): 8807–8864. doi:10.1021/cr500235v. PMID   25144663.
  5. ↑ D. Landini; F. Rolla (1978). "Sulfide Synthesis In Preparation Of Dialkyl And Alkyl Aryl Sulfides: Neopentyl Phenyl Sulfide". Org. Synth. 58: 143. doi:10.15227/orgsyn.058.0143.
  6. ↑ Hoyle, Charles E.; Bowman, Christopher N. (2010-02-22). "Thiol-Ene Click Chemistry". Angewandte Chemie International Edition. 49 (9): 1540–1573. doi:10.1002/anie.200903924. PMID   20166107.
  7. ↑ Stewart, Charles D. (2006). Weapons of mass casualties and terrorism response handbook. Boston: Jones and Bartlett. p. 47. ISBN   0-7637-2425-4.
  8. ↑ Brendsma & Arens 1967, p. 596.
  9. ↑ Brendsma & Arens 1967, p. 601.
  10. ↑ Brendsma & Arens 1967, p. 587.
  11. ↑ Brendsma & Arens 1967, pp. 576–578.
  12. ↑ Richter, Andreas M.; Engels, Volkmar; Beye, Norbert; Fanghänel, Egon (1989) [26 April 1989]. "Organische Elektronenleiter und Vorstufen IX: Zur Darstellung von Hexa-natrium-benzenhexathiolat aus Hexakis-benzylthio-benzen" [Organic electron-conductive materials and precursors IX: On synthesis of hexasodium benzenehexathiolate from hexakis(benzylthio)benzene]. Zeitschrift für Chemie (in German). 29 (12): 444. doi:10.1002/zfch.19890291206. Thioethergruppen können mit Alkali- bzw. Erdalkalimetallen in flüssigem Ammoniak oder in Aminen reduktiv entalkyliert werden. Orientierende Versuche ergaben, daß bei den Hexakisalkylthio-benzenen in flüssigem Ammoniak mit Natrium nicht nur die Alkyl-S-, sondern auch die Aryl-S-Bindung gebrochen wird.[Thioethers can be reductively dealkylated with alkali (resp. earth-alkali) metals in liquid ammonia or amines. Exploratory investigations revealed that not only the alkyl-S but also the aryl-S bonds cleave for hexakis(alkylthio)benzenes in liquid ammonia with sodium.]{{cite journal}}: CS1 maint: multiple names: authors list (link)
  13. ↑ Brendsma & Arens 1967, p. 581.
  14. ↑ Brendsma & Arens 1967, pp. 555–559.

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