Thionyl bromide

Thionyl bromide

Names
IUPAC name Thionyl bromide
Other names Sulfur oxy dibromide
Identifiers
CAS Registry Number	507-16-4 N
ChemSpider	61483 Y
InChI InChI=1S/Br2OS/c1-4(2)3 Y Key: HFRXJVQOXRXOPP-UHFFFAOYSA-N Y InChI=1/Br2OS/c1-4(2)3 Key: HFRXJVQOXRXOPP-UHFFFAOYAY
Jmol-3D images	Image
PubChem	68176
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
MSDS	"External MSDS"
Main hazards	sensitive to water source of bromine, HBr
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 noted otherwise, data is given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
N verify (what is: Y/N?)
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

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. 

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