The rotary evaporator works at low pressure and consists of five elements:
- Evaporation flask, in which the solution to be evaporated is inserted
- Thermostatic bath, in which the evaporation flask is immersed to keep the solution at the appropriate temperature
- Mechanism to rotate the evaporating flask
- Condenser to break down most of the vapours that develop during the process
- Vacuum pump, generally of a membrane type
The application of an appropriate vacuum lowers the boiling temperature of the solvent.
Under vacuum, all the solvents boil, and then evaporate, at lower temperatures than those necessary working at atmospheric pressure. The vacuum pump is one of the fundamental components of the rotary evaporator. Further help is given by heating the evaporation flask through the thermostatic bath. The rotation of the flask, creating a veil of the solution, continuously renewed on the surface of the flask, further increases the evaporation speed.
The solvent vapours move away and, when the condenser surface is cooled, condense and are collected in drops in the collection flask.
The trap is useful to completely avoid the risk of foams and splashes going into the evaporating flask.
The solution to be evaporated is fed into the evaporation flask, which is connected to the rotation device and to the condenser connection.
The evaporation flask is immersed in the heating bath and rotation is started, the vacuum is applied to the system and evaporation begins.
- 100°C and 1013mbar
- 80°C and 550mbar
- 60°C and 300mbar
- 40°C and 72mbar
Rotation speed: 39rpm