Sulfonyl halide

In chemistry, a sulfonyl halide consists of a sulfonyl (>S(=O)₂) group singly bonded to a halogen atom. They have the general formula RSO₂X, where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series.^[1][2]

Sulfonyl halides have tetrahedral sulfur centres attached to two oxygen atoms, an organic radical, and a halide. In a representative example, methanesulfonyl chloride, the S=O, S−C, and S−Cl bond distances are respectively 142.4, 176.3, and 204.6 pm.^[3]

Sulfonyl chlorides

General structure of a sulfonic acid chloride

Sulfonic acid chlorides, or sulfonyl chlorides, are a sulfonyl halide with the general formula RSO₂Cl.

Production

Arylsulfonyl chlorides are made industrially in a two-step, one-pot reaction from an arene (in this case, benzene) and chlorosulfuric acid:^[4]

C₆H₆ + HOSO₂Cl → C₆H₅SO₃H + HCl

C₆H₅SO₃H + HOSO₂Cl → C₆H₅SO₂Cl + H₂SO₄

The intermediate benzenesulfonic acid can be chlorinated with thionyl chloride as well. Benzenesulfonyl chloride, the most important sulfonyl halide, can also be produced by treating sodium benzenesulfonate with phosphorus pentachlorides.^[5]

Benzenediazonium chloride reacts with sulfur dioxide and copper(I) chloride to give the sulfonyl chloride:

[C₆H₅N₂]Cl + SO₂ → C₆H₅SO₂Cl + N₂

For alkylsulfonyl chlorides, one synthetic procedure is the Reed reaction:

RH + SO₂ + Cl₂ → RSO₂Cl + HCl

Reactions

Sulfonyl chlorides react with water to give the corresponding sulfonic acid:

RSO₂Cl + H₂O → RSO₃H + HCl

These compounds react readily with many other nucleophiles as well, most notably alcohols and amines (see Hinsberg reaction). If the nucleophile is an alcohol, the product is a sulfonate ester; if it is an amine, the product is a sulfonamide:^{[citation needed]}

RSO₂Cl + R'₂NH → RSO₂NR'₂ + HCl

However, sulfonyl chlorides also react frequently as a source of RSO⁻
₂ and Cl⁺.^[6] For example benzenesulfonyl chloride chlorinates ketene acetals^[7] and mesyl chloride Friedel-Crafts–chlorinates para-xylene.^[8] Using sodium sulfite as the nucleophilic reagent, p-toluenesulfonyl chloride is converted to its sulfinate salt, CH₃C₆H₄SO₂Na.^[9] Chlorosulfonated alkanes are susceptible to crosslinking via reactions with various nucleophiles.^[10]

Sulfonyl chlorides readily undergo Friedel–Crafts reactions with arenes giving sulfones, for example:^{[citation needed][dubious – discuss]}

RSO₂Cl + C₆H₆ → RSO₂C₆H₅ + HCl

A readily available arylsulfonyl chloride source is tosyl chloride.^[11] The desulfonation of arylsulfonyl chlorides provides a route to aryl chlorides:

ArSO₂Cl → ArCl + SO₂

1,2,4-Trichlorobenzene is made industrially in this way.

Treatment of alkanesulfonyl chlorides having α-hydrogens with amine bases can give sulfenes, highly unstable species that can be trapped:

RCH₂SO₂Cl → RCH=SO₂ + HCl

Reduction with tetrathiotungstate ions (WS2−4) induces dimerization to the disulfide.^[12]

Common sulfonyl chlorides

Chlorosulfonated polyethylene (CSPE) is produced industrially by chlorosulfonation of polyethylene. CSPE is noted for its toughness, hence its use for roofing shingles.^[10]

An industrially important derivative is benzenesulfonyl chloride. In the laboratory, useful reagents include tosyl chloride, brosyl chloride, nosyl chloride and mesyl chloride.

Sulfonyl fluorides

Sulfonyl fluorides have the general formula RSO₂F. They can be produced by treating sulfonic acids with sulfur tetrafluoride:^[13]

SF₄ + RSO₃H → SOF₂ + RSO₂F + HF

Perfluorooctanesulfonyl derivatives, such as PFOS, are produced from their sulfonyl fluoride, which are produced by electrofluorination^[14]

In the molecular biology, sulfonyl fluorides are used to label proteins. They specifically react with serine, threonine, tyrosine, lysine, cysteine, and histidine residues. The fluorides are more resistant than the corresponding chlorides and are therefore better suited to this task.^[15]

Some sulfonyl fluorides can also be used as deoxyfluorinating reagents, such as 2-pyridinesulfonyl fluoride (PyFluor) and N-tosyl-4-chlorobenzenesulfonimidoyl fluoride (SulfoxFluor).^[16][17]

Sulfonyl bromides

Sulfonyl bromides have the general formula RSO₂Br. In contrast to sulfonyl chlorides, sulfonyl bromides readily undergo light-induced homolysis affording sulfonyl radicals, which can add to alkenes, as illustrated by the use of bromomethanesulfonyl bromide, BrCH₂SO₂Br in Ramberg–Bäcklund reaction syntheses.^[18][19]

Sulfonyl iodides

Sulfonyl iodides, having the general formula RSO₂I, are quite light-sensitive. Methanesulfonyl iodide evolves iodine in vacuum and branched-alkyl sulfonyl iodides are worse.^[20] Perfluoroalkanesulfonyl iodides, prepared by reaction between silver perfluoroalkanesulfinates and iodine in dichloromethane at −30 °C, react with alkenes to form the normal adducts, RFSO₂CH₂CHIR and the adducts resulting from loss of SO₂, RFCH₂CHIR.^[21]

Arenesulfonyl iodides, prepared from reaction of arenesulfinates or arenehydrazides with iodine, are much more stable^[20] and can initiate the synthesis of poly(methyl methacrylate) containing C–I, C–Br and C–Cl chain ends.^[22] Their reduction with silver gives the disulfone:^[20]

2 ArSO₂I + 2Ag → (ArSO₂)₂ + 2 AgI

In popular culture

In the episode "Encyclopedia Galactica" of his TV series Cosmos: A Personal Voyage, Carl Sagan speculates that some intelligent extraterrestrial beings might have a genetic code based on polyaromatic sulfonyl halides instead of DNA.

References

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2. Drabowicz, J.; Kiełbasiński, P.; Łyżwa, P.; Zając, A.; Mikołajczyk, M. (2008). N. Kambe (ed.). Alkanesulfonyl Halides. Science of Synthesis. Vol. 39. pp. 19–38. ISBN 9781588905307.
3. Hargittai, Magdolna; Hargittai, István (1973). "On the molecular structure of methane sulfonyl chloride as studied by electron diffraction". J. Chem. Phys. 59 (5): 2513. Bibcode:1973JChPh..59.2513H. doi:10.1063/1.1680366.
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6. Dong Jiajia; Krasnova, Larissa; Finn, M. G.; Sharpless, K. Barry (2014). "Sulfur(VI) fluoride exchange (SuFEx)". Angewandte Chemie (International ed. In English). 53 (36). Wiley-VCH: 9433. doi:10.1002/anie.201309399. PMID 25112519.
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14. Lehmler, H. J. (2005). "Synthesis of Environmentally Relevant Fluorinated Surfactants—a review". Chemosphere. 58 (11): 1471–1496. Bibcode:2005Chmsp..58.1471L. doi:10.1016/j.chemosphere.2004.11.078. PMID 15694468.
15. Narayanan, Arjun; Jones, Lyn H. (2015). "Sulfonyl fluorides as privileged warheads in chemical biology". Chemical Science. 6 (5): 2650–2659. doi:10.1039/C5SC00408J. PMC 5489032. PMID 28706662.
16. Nielsen, Matthew K.; Ugaz, Christian R.; Li, Wenping; Doyle, Abigail G. (5 August 2015). "PyFluor: A Low-Cost, Stable, and Selective Deoxyfluorination Reagent". Journal of the American Chemical Society. 137 (30): 9571–9574. Bibcode:2015JAChS.137.9571N. doi:10.1021/jacs.5b06307. PMID 26177230.
17. Guo, Junkai; Kuang, Cuiwen; Rong, Jian; Li, Lingchun; Ni, Chuanfa; Hu, Jinbo (28 May 2019). "Rapid Deoxyfluorination of Alcohols with N-Tosyl-4-chlorobenzenesulfonimidoyl Fluoride (SulfoxFluor) at Room Temperature". Chemistry – A European Journal. 25 (30): 7259–7264. doi:10.1002/chem.201901176. PMID 30869818. S2CID 76667829.
18. Block, E.; Aslam, M. (1993). "A General Synthetic Method for the Preparation of Conjugated Dienes from Olefins using Bromomethanesulfonyl Bromide: 1,2-Dimethylenecyclohexane". Organic Syntheses; Collected Volumes, vol. Coll. Vol. 8, p. 212.
19. Block, E.; Aslam, M.; Eswarakrishnan, V.; Gebreyes, K.; Hutchinson, J.; Iyer, R.; Laffitte, J.-A.; Wall, A. (1986). "α-Haloalkanesulfonyl Bromides in Organic Synthesis. 5. Versatile Reagents for the Synthesis of Conjugated Polyenes, Enones and 1,3-Oxathiole 1,1-Dioxides". J. Am. Chem. Soc. 108 (15): 4568–4580. Bibcode:1986JAChS.108.4568B. doi:10.1021/ja00275a051.
20. Danehy, James P. (1971). "The Sulfur–Iodine Bond". In Senning, Alexander (ed.). Sulfur in Organic and Inorganic Chemistry. Vol. 1. New York: Marcel Dekker. pp. 336–337. ISBN 0-8247-1615-9. LCCN 70-154612.
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22. Percec, V.; Grigoras, C. (2005). "Arenesulfonyl iodides: The third universal class of functional initiators for the metal-catalyzed living radical polymerization of methacrylates and styrenes". Journal of Polymer Science Part A: Polymer Chemistry. 43 (17): 3920–3931. Bibcode:2005JPoSA..43.3920P. doi:10.1002/pola.20860.