Chlorosulfonyl isocyanate is the chemical compound ClSO2NCO, known as CSI. This compound is a versatile reagent in organic synthesis.
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IUPAC name
Chlorosulfonyl isocyanate
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Other names
N-Carbonylsulfamyl chloride
Chloropyrosulfonyl isocyanate Sulfuryl chloride isocyanate | |
Identifiers | |
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3D model (JSmol)
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ChemSpider |
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ECHA InfoCard | 100.013.378 |
EC Number |
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PubChem CID
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UNII |
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CompTox Dashboard (EPA)
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Properties | |
CNClO3S | |
Molar mass | 141.53 g/mol |
Appearance | colorless liquid |
Density | 1.626 g/cm3 |
Melting point | −44 °C (−47 °F; 229 K) |
Boiling point | 107 °C (225 °F; 380 K) |
decomposition | |
Solubility in other solvents | Chlorocarbons MeCN |
Refractive index (nD)
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1.447 |
Structure | |
tetrahedral at S | |
Hazards | |
Occupational safety and health (OHS/OSH): | |
Main hazards
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toxic, corrosive, flammable, reacts violently with water |
GHS labelling: | |
Danger | |
H302, H312, H314, H330, H332, H334 | |
P260, P261, P264, P270, P271, P280, P284, P285, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P304+P341, P305+P351+P338, P310, P312, P320, P321, P322, P330, P342+P311, P363, P403+P233, P405, P501 | |
NFPA 704 (fire diamond) | |
Safety data sheet (SDS) | "External MSDS" |
Related compounds | |
Related compounds
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Thionyl chloride Cyanogen bromide Phosphoryl chloride |
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references
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CSI is prepared by treating cyanogen chloride with sulfur trioxide, the product being distilled directly from the reaction mixture.[1]
In this transformation, both the carbon and the nitrogen termini of CN are functionalized.
The structure of CSI is represented as ClS(O)2-N=C=O. It consists of two electron-withdrawing components, the chlorosulfonyl group (SO2Cl) 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.[2]
The molecule has two electrophilic sites, the carbon and the S(VI) center.[3]
CSI has been employed for the preparation of β-lactams,[4] some of which are medicinally important. Thus, alkenes undergo a [2+2]-cycloaddition to give the sulfonamide. The SO2Cl group can be removed simply by hydrolysis, leaving the secondary amide.[5] Other reactions of CSI:
CSI is toxic, corrosive and reacts violently with water.