The rotary evaporator (or rotovap for short) represents a new addition to the organic chem labs here at Wake Forest. While the instrument looks pretty complicated, it really is pretty simple. The purpose of the rotovap is to remove low boiling organic chemicals, usually solvents, from a mixture of compounds. The rotary evaporator is the method of choice for solvent removal in the modern organic laboratory. The solvents or low boiling compounds are removed by a simple distillation. The rotovap is designed to be operated under a vacuum (to lower a compound's boiling point) and to heat the sample at the same time. A cold finger is used to condense the vapors to a liquid, which are trapped in a separate flask.

Below is a photograph of a rotary evaporator.
The lower red arrow indicates the bath temperature knob.
The middle arrow indicates the point of flask attachment.
The top arrow points to the rotation speed control knob.


 

To use the rotovap, follow these simple steps.

1. Turn on the cooling water, this water will cool the vapors converting them to a liquid that can be trapped.
The lower red arrow indicates the power switch.
 The location of the water reservior and water lines are shown with the upper arrow.  

 2. Turn on the water aspirator to generate a vacuum source.

3. Put your flask on the rotovap, being sure to use a clamp. (The flask should not be more than half full of liquid).
 

4.Close the vacuum valve at the top of the condenser.
To close the vacuum valve, turn it so that the knob is perpendicular to the bench, pointing toward you.

5.Start the flask spinning, this will prevent bumping during the distillation. Lower the flask into the water bath.
 

6.Heat the water bath if necessary.

7. When the solvent has been removed, stop the flask spinning and turn the water bath off.

8. Break the vacuum with the valve at the top of the condenser.

9. Turn off the water to the vacuum and condenser (cooling water).