Sulfonyl halide

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Sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula R-SO2-X 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 are of dominant importance in this series.[1]

Structure[edit]

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 1.424, 1.763, and 2.046 Å.[2]

Sulfonyl chlorides[edit]

General structure of a sulfonic acid chloride

Sulfonic acid chlorides, or sulfonyl chlorides, are a sulfonyl halide with the general formula R-SO2Cl. They are generally colourless compounds that are sensitive to water.

Production[edit]

Arylsulfonyl chlorides are prepared industrially in a two-step, one-pot reaction from the arene and chlorosulfuric acid:[3]

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(V) chlorides.[4]

Phenyldiazonium chloride reacts with sulfur dioxide and HCl 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[edit]

The most obvious reaction is their tendency to hydrolyse to the corresponding sulfonic acid:

C6H5SO2Cl + H2O → C6H5SO3H + HCl

These compounds react readily with nucleophiles other than water, like 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. Using sodium sulfite as the nucleophilic reagent, sulfonyl chlorides convert to the sulfinate salts, e.g., C6H5SO2Na.

Sulfonyl chlorides readily undergo Friedel–Crafts reactions with arenes giving sulfones, for example:

RSO2Cl + C6H6 → RSO2C6H5 + HCl

The desulfonation of arylsulfonyl chlorides provides a way to make aryl chlorides:

ArSO2Cl → ArCl + SO2

1,2,4-Trichlorobenzene is prepared 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

The only industrially important sulfonyl chloride is benzene derivative. In the laboratory, useful reagents include tosyl chloride, brosyl chloride, nosyl chloride and mesyl chloride.

Other sulfonyl halides[edit]

Sulfonyl fluorides[edit]

Sulfonyl fluorides have the general formula R-SO2-F and can be important sulfonyl halide synthetic precursors. For example, "most, if not all" industrially synthesized perfluorooctanesulfonyl derivatives, such as PFOS, have the sulfonyl fluoride as their precursor.[5]

Sulfonyl bromides[edit]

Sulfonyl bromides have the general formula R-SO2-Br. In contrast to sulfonyl chlorides, sulfonyl bromides readily undergo light-induced homolysis affording sulfonyl radicals, which can add to olefins, as illustrated by the use of bromomethanesulfonyl bromide, BrCH2SO2Br in Ramberg-Bäcklund reaction syntheses.[6][7]

Sulfonyl iodides[edit]

Sulfonyl iodides, having the general formula R-SO2-I, are quite light-sensitive. Perfluoroalkanesulfonyl iodides, prepared by reaction between silver perfluoroalkanesulfinates and iodine in dichloromethane at −30 °C, react with olefins to form the normal adducts, RFSO2CH2CHIR and the adducts resulting from loss of SO2, RFCH2CHIR.[8] Arenesulfonyl iodides, prepared from reaction of arenesulfinates or arenehydrazides with iodine, can be used as initiators to facilitate the synthesis of poly(methyl methacrylate) containing C–I, C–Br and C–Cl chain ends.[9]

In popular culture[edit]

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[edit]

  1. ^ Drabowicz, J; Kiełbasiński, P; Łyżwa, P; Zając, A; Mikołajczyk, M (2008). Kambe, N, ed. Alkanesulfonyl Halides. Science of Synthesis 39. pp. 19–38. ISBN 9781588905307. 
  2. ^ Magdolna Hargittai and István Hargittai "On the molecular structure of methane sulfonyl chloride as studied by electron diffraction" J. Chem. Phys. 59, 2513 (1973); http://dx.doi.org/10.1063/1.1680366.
  3. ^ Otto Lindner, Lars Rodefeld "Benzenesulfonic Acids and Their Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry 2005, Wiley-VCH, Weinheim. doi:10.1002/14356007.a03_507
  4. ^ Roger Adams, C. S. Marvel, H. T. Clarke, G. S. Babcock, and T. F. Murray (1921), "Benzenesulfonyl chloride", Org. Synth. 1: 21 ; Coll. Vol. 1: 84 
  5. ^ Lehmler HJ (2005). "Synthesis of environmentally relevant fluorinated surfactants—a review". Chemosphere 58 (11): 1471–96. doi:10.1016/j.chemosphere.2004.11.078. PMID 15694468. 
  6. ^ 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. Coll. Vol. 8: 212 Article. 
  7. ^ 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. Amer. Chem. Soc. 108: 4568–4580. doi:10.1021/ja00275a051. 
  8. ^ Huang W-Y, Hu L-Q (1989). "The chemistry of perfluoroalkanesulfonyl iodides". Journal of Fluorine Chemistry 44 (1): 25–44. doi:10.1016/S0022-1139(00)84369-9. 
  9. ^ 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.