Vacuum adaptor

The vacuum adaptor is used in a distillation set-up: it connects to the lower end of the condenser and serves to direct the distilled liquid into the receiving flask. ... the vacuum adapter has a side-arm which can be connected to a vacuum source. The advantage of a vacuum adaptor over a bent adaptor is the ability to serve not only in simple or fractional distillations, but also in a vacuum distillation. If the lower joint is connected to a round-bottom flask, the system is closed to the atmosphere and can be connected to a vacuum source to create a distillation set-up under reduced pressure. [orgchem.colorado.edu/Technique/Equipment/Rxnglass/Vacadaptor.html]