Phosphoryl chloride

From Sciencemadness Wiki
Jump to: navigation, search
Phosphoryl chloride
Names
IUPAC name
Phosphoryl trichloride
Other names
Phosphorus oxychloride
Phosphoric trichloride
Phosphorus trichloride oxide
Phosphorous(V) oxychloride
Trichlorophosphate
Properties
POCl3
Molar mass 153.33 g/mol
Appearance Colorless fuming liquid
Odor Pungent, acidic
Density 1.645 g/cm3
Melting point 1.25 °C (34.25 °F; 274.40 K)
Boiling point 105.8 °C (222.4 °F; 378.9 K)
Reacts
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)
Thermochemistry
-615.7 kJ/mol
Hazards
Safety data sheet Sigma-Aldrich
Flash point Non-flammable
Related compounds
Related compounds
Phosphoryl bromide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Infobox references

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.

Properties

Chemical

Phosphorus oxychloride reacts with water to form phosphoric acid and hydrogen chloride fumes.

POCl3 + 3 H2O → H3PO4 + 3 HCl

Physical

Phosphoryl chloride is a colorless liquid which fumes in air.

Availability

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.

Preparation

Phosphoryl chloride can be prepared by oxidizing phosphorus trichloride with pure oxygen, between 20-50 °C. Air is ineffective for this reaction.

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.

Reduction of tricalcium phosphate with carbon in the presence of chlorine gas is more accessible route, although it occurs at high temperatures.

Ca3(PO4)2 + 6 C + 6 Cl2 → 2 POCl3 + 3 CaCl2 + 6 CO

Projects

  • Make phosphate esters
  • Make nitriles from amides
  • Vilsmeier–Haack reaction

Handling

Safety

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.

Storage

Phosphoryl chloride should be stored in Schlenk flasks, as they're the best storage containers for air and water sensitive reagents.

Disposal

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.

References

Relevant Sciencemadness threads