Microscale: Removal of small amounts of solvents

The usual way to remove a solvent is with a rotary evaporator. A solvent can be removed under reduced pressure using round-bottom flask with ground-glass joints of a suitable volume (e.g. 5 ml or 10 ml). However, there are other alternatives:

  • By gas stream. The vessel is heated in a water bath and the solvent is forced to evaporate by means of a gas stream. It is advisable to use an inert gas such as nitrogen, since the oxygen in the air can oxidize many compounds. This operation should be carried out in a fume hood to avoid accumulation of hazardous or harmful vapors in the workplace.
  • By application of vacuum. In the Figure, different options for removing a solvent under vacuum on a small scale are shown.

 

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