Chlorosulfonyl isocyanate
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2007-11-14T22:39:08Z
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{{Chembox new
| Name = Chlorosulfonyl isocyanate
| ImageFile = Chlorosulfonyl-isocyanate-2D.png
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| ImageName = Chlorosulfonyl isocyanate
| ImageFile1 = Chlorosulfonyl-isocyanate-3D-vdW.png
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| ImageName1 = Chlorosulfonyl isocyanate
| IUPACName = Chlorosulfonyl isocyanate
| OtherNames = N-Carbonylsulfamyl chloride<br />Isocyanic acid, anhydride<br />chloropyrosulfonyl isocyanate
| Section1 = {{Chembox Identifiers
| SMILES = ClS(=O)(=O)\N=C=O
| CASNo = 1189-71-5
}}
| Section2 = {{Chembox Properties
| Formula = CNClO<sub>3</sub>S
| MolarMass = 141.53 g/mol
| Appearance = colorless liquid
| Density = 1.626 g/cm<sup>3</sup>
| Solubility = decomp.
| Solvent = other solvents
| SolubleOther = Chlorocarbons</br>[[Acetonitrile|MeCN]]
| MeltingPt = -44 °C
| BoilingPt = 107 °C
| RefractIndex = 1.447
}}
| Section3 = {{Chembox Structure
| MolShape = tetrahedral at S
| Dipole =
}}
| Section7 = {{Chembox Hazards
| ExternalMSDS =
| MainHazards = toxic, corrosive<br />hydrolyzes violently
}}
| Section8 = {{Chembox Related
| Function = compounds
| OtherFunctn = SOCl<sub>2</sub></br> [[cyanogen bromide|BrCN]], POCl<sub>3</sub>
}}
}}
'''Chlorosulfonyl isocyanate''' is the chemical compound ClSO<sub>2</sub>NCO, known as CSI. This compound is a versatile reagent in [[organic synthesis]].
==Preparation, structure, handling==
CSI is prepared by treating [[cyanogen chloride]] with [[sulfur trioxide]], the product being distilled directly from the reaction mixture.<ref>Graf, R. "Chlorosulfonyl Isocyanate" [[Organic Syntheses]], Collected Volume 5, pages 226ff.</ref>
::SO<sub>3</sub> + ClCN → ClSO<sub>2</sub>NCO
In this transformation, both the carbon and the nitrogen termini of CN are functionalized.
The structure of CSI is represented as ClS(O)<sub>2</sub>-N=C=O. It consists of two electron-withdrawing components, the chlorosulfonyl group (SO<sub>2</sub>Cl) and the [[isocyanate]] group (-N=C=O). Because of its resulting electrophilicity, the use of CSI in chemical synthesis requires relatively inert solvents such as chlorocarbons, acetonitrile, and ethers.<ref>Miller, M. J.; Ghosh, M.; Guzzo, P. R.; Vogt, P. F.; Hu, J.; Filzen, G. F.; Geyer, A. G. "Chlorosulfonyl Isocyanate" in "Encyclopedia of Reagents for Organic Synthesis" 2005 John Wiley & Sons: New York.</ref>
==Uses==
The molecule has two electrophilic sites, the carbon and the S(VI) center.<ref>D. N. Dhar, K. S. K. Murthy "Recent Advances in the Chemistry of Chlorosulfonyl Isocyanate" Synthesis 1986; pages 437-449.</ref>
CSI has been employed for the preparation of β-[[lactam]]s, some of which are medicinally important. Thus, alkenes undergo a<nowiki>[2+2]</nowiki>-cycloaddition to give the sulfonamide. The SO<sub>2</sub>Cl group can be removed simply by hydrolysis, leaving the secondary amide.<ref>Cremlyn, R. J. “An Introduction to Organosulfur Chemistry” John Wiley and Sons: Chichester (1996). ISBN 0-471-95512-4</ref>
Other reactions of CSI:
*Cycloaddition to alkynes to give 1,2,3-oxathiazine-2,2-dioxide-6-chlorides.
*Conversion of primary alcohols to [[urethane]]s.<ref>Burgess, E. M.; Penton, Jr., H. R.; Taylor, E. A.; Williams, W. M. "Conversion of Primary Alcohols to Urethanes via the Inner Salt of Triethylammonium Hydroxide: Methyl (Carboxylsulfamoyl) Triethylammonium Hydroxide Methyl n-Hexylcarbamate" Organic Syntheses, Coll. Vol. 6, p.788</ref>
*Conversion of [[carboxylic acid]]s and the acid chlorides into [[nitrile]]s.
*Preparation of N,N-disubstituted [[sulfamide]]s, R<sub>2</sub>NSO<sub>2</sub>NH<sub>2</sub>
==Safety considerations==
CSI is toxic, corrosive and reacts violently with water. It cannot be stored in glass-stoppered flasks, requiring instead polyethylene bottles.
==References==
<references/>
[[Category:Inorganic carbon compounds]]
[[Category:Oxides]]
[[Category:Chlorides]]
[[Category:Reagents for organic chemistry]]
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