Phosphorus pentabromide
| Names | |
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| IUPAC name
Tetrabromophosphanium bromide | |
Other names
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| Identifiers | |
3D model (JSmol) |
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| ChemSpider | |
| ECHA InfoCard | 100.029.260 |
| EC Number |
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PubChem CID |
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| UNII | |
| UN number | 2691 |
CompTox Dashboard (EPA) |
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| Properties | |
| PBr5 | |
| Molar mass | 430.494 g·mol−1 |
| Appearance | Yellow crystalline solid |
| Density | 3.61 g/cm3 |
| Melting point | ca. 100 °C (decomposes) |
| Boiling point | 106 °C (223 °F; 379 K) (decomposes) |
| Reacts with water | |
| Solubility | Decomposes in ethanol Soluble in CCl4 and CS2 |
| Hazards | |
| Occupational safety and health (OHS/OSH): | |
Main hazards |
Causes severe skin burns and eye damage |
| GHS labelling: | |
| Danger | |
| H314 | |
| P260, P264, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P405, P501 | |
| Related compounds | |
Related compounds |
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Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references | |
Phosphorus pentabromide is a reactive, yellow solid of formula PBr5, which has the structure [PBr4]+Br− (tetrabromophosphonium bromide) in the solid state but in the vapor phase is completely dissociated to PBr3 and Br2. Rapid cooling of this phase to 15 K leads to formation of the ionic species phosphorus heptabromide (tetrabromophosphonium tribromide [PBr4]+[Br3]−).
It can be used in organic chemistry to convert carboxylic acids to acyl bromides. It is highly corrosive. It strongly irritates skin and eyes. It decomposes above 100 °C to give phosphorus tribromide and bromine:
Reversing this equilibrium to generate PBr5 by addition of Br2 to PBr3 is difficult in practice because the product is susceptible to further addition to yield phosphorus heptabromide [PBr4]+[Br3]−.