Chlorosulfonyl isocyanate

Chlorosulfonyl isocyanate is the chemical compound ClSO₂NCO, known as CSI. This compound is a versatile reagent in organic synthesis.

Chlorosulfonyl isocyanate

Chlorosulfonyl isocyanate
Chlorosulfonyl isocyanate
Names
IUPAC name Chlorosulfonyl isocyanate
Other names N-Carbonylsulfamyl chloride Chloropyrosulfonyl isocyanate Sulfuryl chloride isocyanate
Identifiers
CAS Number	1189-71-5 Y
3D model (JSmol)	Interactive image
ChemSpider	64080 Y
ECHA InfoCard	100.013.378
EC Number	214-715-2
PubChem CID	70918
UNII	2903Y990SM Y
CompTox Dashboard (EPA)	DTXSID0061585
InChI InChI=1S/CClNO3S/c2-7(5,6)3-1-4 Y Key: WRJWRGBVPUUDLA-UHFFFAOYSA-N Y InChI=1/CClNO3S/c2-7(5,6)3-1-4 Key: WRJWRGBVPUUDLA-UHFFFAOYAX
SMILES ClS(=O)(=O)N=C=O
Properties
Chemical formula	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)
Solubility in water	decomposition
Solubility in other solvents	Chlorocarbons MeCN
Refractive index (nD)	1.447
Structure
Molecular shape	tetrahedral at S
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	toxic, corrosive, flammable, reacts violently with water
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H302, H312, H314, H330, H332, H334
Precautionary statements	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)	3 1 2 W
Safety data sheet (SDS)	"External MSDS"
Related compounds
Related compounds	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). Y verify (what is YN ?) Infobox references

Preparation, structure, handling

CSI is prepared by treating cyanogen chloride with sulfur trioxide, the product being distilled directly from the reaction mixture.^[1]

SO₃ + ClCN → ClSO₂NCO

In this transformation, both the carbon and the nitrogen termini of CN are functionalized.

The structure of CSI is represented as Cl−S(=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]

Uses

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:

• Cycloaddition to alkynes to give 1,2,3-oxathiazine-2,2-dioxide-6-chlorides.
• Conversion of primary alcohols to carbamates.^[6]
• Conversion of carboxylic acids and the acid chlorides into nitriles.
• Preparation of N,N-disubstituted sulfamides, R₂NSO₂NH₂
• Preparation of Burgess reagent

Safety considerations

CSI is toxic, corrosive and reacts violently with water.