Thionyl bromide

Thionyl bromide

Names
IUPAC name Thionyl bromide
Other names Sulfur oxy dibromide
Identifiers
CAS Number	507-16-4
3D model (Jmol)	Interactive image
ChemSpider	61483
ECHA InfoCard	100.007.332
PubChem	68176
InChI InChI=1S/Br2OS/c1-4(2)3 Key: HFRXJVQOXRXOPP-UHFFFAOYSA-N InChI=1/Br2OS/c1-4(2)3 Key: HFRXJVQOXRXOPP-UHFFFAOYAY
SMILES BrS(Br)=O
Properties
Chemical formula	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
Solubility in water	decomposes
Solubility	reacts in HBr, acetone, and alcohol soluble in benzene, toluene, ether
Structure
Molecular shape	trigonal pyramidal
Hazards
Main hazards	sensitive to water source of bromine, HBr
Safety data sheet	"External MSDS"
R-phrases	R14 R20/21/22 R29[1] R34
S-phrases	(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).
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Infobox 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

Safety

SOBr₂ hydrolyzes readily to release dangerous HBr and acts as a lachrymator.

References

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

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