Phosphoryl bromide

Phosphoryl bromide, also known as phosphorus oxybromide, is an inorganic compound with the formula POBr₃.^[3]

Phosphoryl bromide

Names
Other names Phosphorus oxybromide
Identifiers
CAS Number	7789-59-5 Y
3D model (JSmol)	Interactive image
ChemSpider	23015
ECHA InfoCard	100.029.252
EC Number	232-177-7
PubChem CID	24613
UNII	H98H8Y87QQ Y
UN number	1939 2576
CompTox Dashboard (EPA)	DTXSID2064868
InChI InChI=1S/Br3OP/c1-5(2,3)4 Key: UXCDUFKZSUBXGM-UHFFFAOYSA-N InChI=1/Br3OP/c1-5(2,3)4 Key: UXCDUFKZSUBXGM-UHFFFAOYAH
SMILES O=P(Br)(Br)Br
Properties
Chemical formula	POBr3
Molar mass	286.685 g·mol−1
Appearance	Colorless crystals or thin plates with a faint orange tint
Odor	Pungent[1]
Density	2.822 g/cm3[1]
Melting point	56 °C (133 °F; 329 K)
Boiling point	192 °C (378 °F; 465 K)
Solubility in water	Reacts violently with water[1]
Solubility	Soluble in diethyl ether, benzene, chloroform, carbon disulfide, and concentrated sulfuric acid[1]
Structure[2]
Space group	Pnma, No. 62
Lattice constant	a = 9.467 Å, b = 9.938 Å, c = 6.192 Å
Formula units (Z)	4
Molecular shape	Tetrahedral at the P atom
Hazards
Occupational safety and health (OHS/OSH):
Main hazards	Corrosive to tissue
GHS labelling:
Pictograms
Signal word	Danger
Hazard statements	H290, H314, H335
Precautionary statements	P234, P260, P261, P264, P271, P280, P301+P330+P331, P303+P361+P353, P304+P340, P305+P351+P338, P310, P312, P321, P363, P390, P403+P233, P404, P405, P501
Related compounds
Related compounds	Phosphorus tribromide Thiophosphoryl bromide Phosphoryl fluoride Phosphoryl chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Preparation

Phosphoryl bromide is prepared by the reaction between phosphorus pentabromide and phosphorus pentoxide:^[4][5]

3 PBr₅ + P₂O₅ → 5 POBr₃

It can also be prepared via the slow addition of liquid bromine to phosphorus tribromide at 0 °C, followed by the slow addition of water and vacuum distillation of the resulting slurry.^{[citation needed]}

Structure and properties

Phosphoryl bromide forms colorless crystals or thin plates with a faint orange tint.^[6] Its crystals belong to the orthorhombic space group Pnma,^[2][7] with intermolecular Br–O bridges creating infinite chains within the structure. The intermolecular bonding causes distortions from the C_3v symmetry found in the free molecule.^[2]

It is stored in sealed glass ampoules.

Uses

Phosphoryl bromide finds use as a specialist brominating agent.

Safety

Phosphoryl bromide reacts violently with water evolving heat, forming phosphoric acid and hydrobromic acid. Reacts with organic compounds to cause fire. Evolves highly toxic and corrosive gases when exposed to fire. When heated to decomposition, it emits highly toxic fumes like bromides, oxybromides and oxides of phosphorus. It is corrosive to metals and tissues.^[6][1]

References

1. https://pubchem.ncbi.nlm.nih.gov/compound/Phosphorus-oxybromide
2. Templeton, Lieselotte K.; Templeton, David H. (1971). "The crystal structure of POBr₃: space group and refinement by least squares". Acta Crystallogr. B. 27 (8): 1678–1679. doi:10.1107/S0567740871004564. S2CID 97905269.
3. Greenwood, Norman N.; Earnshaw, Alan (1997). Chemistry of the Elements (2nd ed.). Butterworth-Heinemann. pp. 501–503. ISBN 978-0-08-037941-8.
4. Hönigschmid, O.; Hirschbold‐Wittner, F. (1940). "Das Atomgewicht des Phosphors. Analyse des Phosphoroxybromids". Zeitschrift für anorganische und allgemeine Chemie (in German). 243 (4): 355–360. doi:10.1002/zaac.19402430406. ISSN 1521-3749.
5. Booth, Harold S.; Seegmiller, C. G.; Baker, Philip S.; Wexler, Sol; Johnson, Roy D. (2007-01-05), Fernelius, W. Conard (ed.), "Phosphorus(V) Oxybromide: (Phosphoryl Tribromide)", Inorganic Syntheses, Hoboken, NJ, USA: John Wiley & Sons, Inc., pp. 151–152, doi:10.1002/9780470132333.ch44, ISBN 978-0-470-13233-3, retrieved 2020-09-30
6. Perry, Dale L. (2011). Handbook of Inorganic Compounds (2nd ed.). Boca Raton: Taylor & Francis. p. 310. ISBN 978-1-4398-1461-1. OCLC 587104373.
7. Okuda, Tsutomu.; Hosokawa, Kazuto.; Yamada, Koji.; Furukawa, Yoshihiro.; Negita, Hisao. (1975). "Structural study of phosphoryl bromide by means of nuclear quadrupole resonance". Inorganic Chemistry. 14 (5): 1207–1209. doi:10.1021/ic50147a048. ISSN 0020-1669.