Thionyl bromide

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 + 2 HBr → SOBr2 + 2 HCl
Thionyl bromide
Structure of the thionyl bromide molecule
3D model of a thionyl bromide molecule
Names
IUPAC name
Thionyl bromide
Other names
Sulfur oxy dibromide
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.007.332
UNII
Properties
SOBr2
Molar mass 207.87 g/mol
Appearance colorless liquid
Density 2.688 g/mL, liquid
Melting point −52 °C (−62 °F; 221 K)
Boiling point 68 °C (154 °F; 341 K) at 40 mmHg
decomposes
Solubility reacts in HBr, acetone, and alcohol
soluble in benzene, toluene, ether
Structure
trigonal pyramidal
Hazards
Main hazards Readily decomposes in air to toxic gases
Safety data sheet "External MSDS"
R-phrases (outdated) R14 R20/21/22 R29[1] R34
S-phrases (outdated) (S1/2) S8[1] S26 S30 S36/37/39 S45
Flash point Non-flammable
Related compounds
Related compounds
 SOCl2, SeOCl2;

PBr3, Br2

Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
N verify (what is YN ?)
Infobox references

Thionyl bromide will convert alcohols to alkyl bromides and can be used for brominations of certain α,β-unsaturated carbonyl compounds.

Safety

SOBr2 hydrolyzes readily in air to release dangerous fumes of sulfur dioxide and hydrogen bromide.

SOBr2 + H2O → SO2 + 2 HBr

References
  1. http://fscimage.fishersci.com/msds/12624.htm

Mundy, B. P. (2004). "Thionyl Bromide". In Paquette, E. (ed.). Encyclopedia of Reagents for Organic Synthesis. New York: J. Wiley & Sons. doi:10.1002/047084289X.rt098. ISBN 0471936235.

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