Thionyl bromide

Chembox new
Name = Thionyl bromide
ImageFile = Thionyl-bromide.png ImageName = Structure of the thionyl bromide molecule
ImageFile1 = Thionyl-bromide-3D-space-filling.png ImageName1 = 3D model of a thionyl bromide molecule
IUPACName = Thionyl bromide
OtherNames = Sulfur oxy dibromide
Section1 = Chembox Identifiers
SMILES = O=S(Br)Br
CASNo = 507-16-4
RTECS =
Section2 = Chembox Properties
Formula = SOBr₂
MolarMass = 207.87 g/mol
Appearance = colorless liquid
Density = 2.688 g/mL, liquid
Solubility = decomposes violently
MeltingPt = –52 °C
BoilingPt = 68 °C/40 mmHg
Viscosity =
Section3 = Chembox Structure
MolShape = trigonal pyramidal
Dipole =
Section7 = Chembox Hazards
ExternalMSDS =
MainHazards = dangerously sensitive to water
source of bromine, HBr
FlashPt = nonflammable
RPhrases = 14-20/21-34
SPhrases = 26-36/37/39-45
Section8 = Chembox Other
OtherCpds =SOCl₂, SeOCl₂; PBr₃, Br₂

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

afety

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

References

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