How to Use a Rotary Evaporator (Rotavap)

Ensure your round bottom flask is less than half full and verify that the vacuum pump is turned on before beginning.

Familiarize yourself with the three main controls: the rotation knob, the up-and-down switch, and the vacuum vent valve. The vent valve connects to atmosphere when pointing up and to the vacuum pump when pointing down.

Couple the round bottom flask to the rotavap glass joint and secure it with a cake clip, ensuring the small side straddles the small neck and the large side straddles the large neck.

Connect the system to the vacuum by pointing the vent valve downward toward the vacuum hose, then immediately start the rotation at half to three-quarters speed for small flasks.

Lower the flask into the water bath to initiate solvent evaporation. You should see solvent dripping down the cold finger into the collection reservoir.

Allow the rotavap to run until no liquid remains in the round bottom flask. Stop the rotation and lift the flask out of the water bath to check completion.

Vent the system by turning the valve upward and listen for hissing. Remove the cake clip and carefully remove your flask from the rotavap.

Note that the round bottom flask may appear empty but could contain a thin liquid layer spread on the walls. The collected solvent in the reservoir is classified as waste.