| IUPAC name
| Other names
Phosphorus trichloride oxide
|Molar mass||153.33 g/mol|
|Appearance||Colorless fuming liquid|
|Melting point||1.25 °C (34.25 °F; 274.40 K)|
|Boiling point||105.8 °C (222.4 °F; 378.9 K)|
|Solubility|| Reacts with alcohols, carboxylic acids|
Soluble in benzoyl chloride, bromine, bromoacetic acid, carbon disulfide, liq. Cl2, liq. HBr, liq. HCl, hydrogen cyanide, liq. H2S, anh. nitric acid, sulfuryl chloride, liq. SO2, SnCl4
Sparingly soluble in liq. HI
|Vapor pressure||40 mmHg (27.3 °C)|
Std enthalpy of
|Safety data sheet||Sigma-Aldrich|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Phosphoryl chloride or phosphorus oxychloride is a fuming colourless liquid, widely used for the synthesis of phosphate esters. It is a colorless fuming liquid, with the formula POCl3.
Phosphorus oxychloride reacts with water to form phosphoric acid and hydrogen chloride fumes.
- POCl3 + 3 H2O → H3PO4 + 3 HCl
Phosphoryl chloride is a colorless liquid which fumes in air.
Is sold by big chemical suppliers, but it's next to impossible to get hold of.
Phosphoryl chloride is listed on Schedule 3 of the Chemical Weapons Convention. Transactions tend to be monitored, especially if large amounts are done.
- 2 PCl3 + O2 → 2 POCl3
Potassium chlorate can also be used as oxidizer, instead of pure oxygen.
Reaction of phosphorus pentachloride with phosphorus pentoxide will also give POCl3:
- 6 PCl5 + P4O10 → 10 POCl3
Heating sodium chloride with phosphorus pentoxide will also give phosphorus oxychloride:
- 2 P2O5 + 3 NaCl → 3 NaPO3 + POCl3
Reduction of tricalcium phosphate with carbon in the presence of chlorine gas is more accessible route, although it requires high temperatures. It should be noted that chlorine and carbon monoxide can form very toxic phosgene.
- Ca3(PO4)2 + 6 C + 6 Cl2 → 2 POCl3 + 3 CaCl2 + 6 CO
- Make phosphate esters
- Make nitriles from amides
- Vilsmeier–Haack reaction
Phosphorus oxychloride is very corrosive and toxic. Wear proper protection when handling the compound. Only work in a fumehood or in a well ventilated place.
Phosphoryl chloride should be stored in Schlenk flasks, as they're the best storage containers for air and water sensitive reagents.
Phosphoryl chloride should be neutralized with a base, such as calcium hydroxide suspension outside or in a well ventilated area. Always add small amounts of POCl3 to prevent splashing. Try not to use carbonates, as they will fizzle and cause some POCl3 to become airborne. Since small amounts of HCl fumes will be formed anyway, use a lidded container in case of runaway.