Thionyl bromide

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Thionyl bromide
General
Systematic name	Thionyl bromide
Other names	Sulfur oxy dibromide
Molecular formula	SOBr2
SMILES	O=S(Br)Br
Molar mass	207.87 g/mol
Appearance	colorless liquid
CAS number	[507-16-4]
Properties
Density and phase	2.688 g/mL, liquid
Solubility in water	decomposes violently
Other solvents	benzene, chlorocarbons
Melting point	–52 °C
Boiling point	68 °C/40 mmHg
Viscosity	? cP at ? °C
Structure
Molecular shape	trigonal pyramidal
Dipole moment	? D
Hazards
MSDS	External MSDS
Main hazards	dangerously sensitive to water source of bromine, HBr
NFPA 704
Flash point	nonflammable
R/S statement	R: 14-20/21-34 S: 26-36/37/39-45
RTECS number	?
Supplementary data page
Structure and properties	n 1.675
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Chalcogen oxyhalides	SOCl2, SeOCl2
Bromination agents	PBr3, Br2
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Thionyl bromide is the chemical compound SOBr₂. It is less stable and less widely used than its chloride analogue, thionyl chloride. It is prepared by the action of hydrogen bromide on thionyl chloride, a characteristic reaction where a stronger acid is converted to a weaker acid:

SOCl₂ + 2HBr → SOBr₂ + 2HCl

Thionyl bromide is used for some brominations of certain α,β-unsaturated carbonyls, and it also converts alcohols to alkyl bromides. Otherwise it hydrolyzes readily to release sulfur dioxide:

SOBr₂ + H₂O → SO₂ + 2HBr

[edit] Safety

SOBr₂ hydrolyzes readily to release dangerous HBr. It also reacts with acetone to give a hazardous lacrymator.

[edit] Reference

Mundy, B. P. "Thionyl Bromide" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York.

[edit] External links

• Links to external chemical sources