Distillation under reduced pressure method is used to purify the liquids in which the liquids
 

Distillation is the process of selectively boiling a component in a liquid mixture and then condensing it thereafter. It is a method of separation that can be applied to either get more of one particular component out of a mixture or to separate it almost completely. Distillation under reduced pressure method is used to purify the liquids which do not decompose at their boiling points, but before reaching their boiling point.