Rotary Evaporators Design

A rotary evaporator is a device used in Chemical Laboratories for efficient and gentle removal of solvents from samples by evaporation.

The main components of a rotary evaporators are:

1. The motor unit which rotates the evaporation flask containing sample material.
2. A vapour duct which acts as an axis for sample rotation, and a vacuum tight conduit for the vapour being drawn off of the sample.
3. A vacuum system (not integral part of the equipment) to substantially reduce the pressure within the evaporator system.
4. A heated fluid (water / thermic fluid) bath to heat the sample being evaporated.
5. A condenser with double coil through which the coolant passes.
6. A condensate collecting flask at the bottom of the condenser, to collect the distilling solvent after it recondenses.
7. A mechanical or motorized mechanism to quickly lift the evaporation flask from the heating bath or lower the heating bath so that the evaporation flask does not remain in contact with bath.

The vacuum evaporators as a class function because lowering the pressure lowers the Boiling Points of component liquids in it. Generally, the component liquids of interest in applications of rotary evaporation are solvents that one desires to remove from a sample after an extraction, for instance, following a natural product isolation or a step in an organic synthesis. Use of a Rotary  Evaporator, therefore allows liquid solvents to be removed without excessive heating of what are often complex and sensitive solvent – solute combinations.

1. The centrifugal force and the frictional force between the wall of the rotating flask and the liquid sample result in the formation of a thin of warm solvent being spread over a large surface.
2. The forces created by the rotation suppress violently, un – predicted boiling/bumping.
3. Allows quick and gentle evaporation of solvents from most samples.
4. Low temperature and vacuum control also help in kerbing bumping/foaming during evaporation process.