Explain preparation and properties of phosphorus trichloride

It may be prepared by the action of phosphorus on thionyl chloride.

P4 + 8SOCl2  816_Phosphorus trichloride.png  4OCl3 + 4SO2 + 2S2Cl2
Lab. Method: it is more conveniently prepared in the laboratory by heating white phosphorus in a current of dry chlorine when phosphorus trichloride distils over.

P4 + 6Cl2  816_Phosphorus trichloride.png  4PCl3

Phosphorus is gently heated in a retort on a water bath and current dry chlorine is passed. Phosphorus trichloride distils over and is collected in a receiver cooled in freezing mixture.

It is redistilled over white phosphorus to remove any phosphorus pentachloride present an impurity.


It is colourless fuming liquid.
It reacts violently with water forming phosphorus acid.

PCl3 + 3HOH  816_Phosphorus trichloride.png  H3PO3 + 3HCl
It reacts with concentrated H2SO4 forming chlorosulphonic acid.
1292_Phosphorus trichloride1.png 

Or, 2H2SO4 + PCl3  816_Phosphorus trichloride.png  HSO3Cl + HPO3 + SO2 + HCl
It reacts with organic compounds containing hydroxyl group.

2328_Phosphorus trichloride2.png 
It directly combines with Cl2, O2 and S. this indicates that it is an unsaturated compound.

PCl3 + Cl2  816_Phosphorus trichloride.png  PCl5

2PCl3 + O2  816_Phosphorus trichloride.png  2POCl3

PCl3 + S  816_Phosphorus trichloride.png  PSCl
It acts as a reducing agent.

PCl3 + SO2Cl2  816_Phosphorus trichloride.png  PCl5 + SO2

PCL3 + SO3  816_Phosphorus trichloride.png  POCL3 + SO2

3PCl3 + S2Cl2  816_Phosphorus trichloride.png  PCL5 + 2PSCl

It reacts with finely divided metals when hot.

12Ag + 4PCl3  816_Phosphorus trichloride.png  12AgCl + P4

6Na + PCl3  816_Phosphorus trichloride.png  3NaCl + Na2P


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