By the action of phosphorus pentachloride, the hydroxyl group is replaced by chlorine.
Molybdenum trichloride, MoC1 31 is obtained when the pentachloride is heated to a temperature of about 250° C. in a current of hydrogen.
Molybdenum pentachloride, MoC1 5r is obtained when molybdenum is gently heated in dry chlorine (L.
Thionyl chloride, SOC1 21 may be obtained by the action of phosphorus pentachloride on sodium sulphite; by the action of sulphur trioxide on sulphur dichloride at 75 -80° C. (Journ.
It may also be obtained by distilling chlorsulphonic acid with phosphorus pentachloride: 2S0 2 C1.