Rotary evaporator is a commonly used experimental instrument in chemical laboratories. It is mainly used to continuously distill large amounts of volatile solvents under reduced pressure. Especially for the concentration of the extract and the distillation of the receiving liquid during chromatographic separation, the reaction product can be separated and purified
The main components of the rotary evaporator include:
The rotating motor drives the sample to rotate, increasing the evaporation surface area of the evaporation flask;
Sealing ring to keep the air tightness of the rotary evaporator system;
Vacuum pump and vacuum controller system are used to reduce the boiling point of the distillation solvent and control the best vacuum to achieve efficient distillation;
Universal heating pot for water and oil, heating the sample and increasing the distillation rate;
Condenser tube, using three-layer condensing design or other condensing agents such as dry ice-acetone to condense samples;
Condensing the sample collection bottle to realize the recovery of the distilled solvent generally requires low temperature.
Mechanical or motor mechanical devices are used to quickly lift the evaporating flask in the heating pot.
Some imported brands are equipped with automatic boiling point recognition, solvent database and quantitative distillation functions, making the operation easier.
As the evaporator is evacuated, the boiling point of the solvent to be distilled decreases. Under normal circumstances, the components distilled from the sample are the target components in chemical research, such as extracting certain natural components from organic synthetic samples. Rotary evaporators are used in most cases to separate low-boiling components, such as hexane and ethyl acetate, which are liquid at room temperature and normal pressure. In addition, through standardized operations, certain components contained in the sample can also be removed.
If the vacuum pump system can reach enough vacuum, high boiling point solvents such as water (standard atmospheric pressure boiling point is 100°C), dimethylformamide (standard atmospheric pressure boiling point is 153°C), dimethyl sulfoxide (standard atmospheric pressure boiling point) 189°C) can also be distilled (for example, if the vacuum is reduced from 760 torr to 5 torr, both dimethyl formamide and dimethyl sulfoxide can boil at 50°C). For example, high-speed centrifugal vortex distillation and other technical research have begun, when many samples need to be distilled in parallel, the current high-speed centrifugal vortex distillation technology has a significant effect, and has begun to be applied to industrial production.
Compared with the vacuum distillation achieved by using a standard distillation glass assembly (without a rotating distillation device) under the action of a vacuum pump, the vacuum distillation of a rotary evaporator has the following advantages:
Due to the inertia and friction between the liquid sample and the evaporation flask, the liquid sample spreads on the inner surface of the evaporation flask and forms a liquid film. Compared with the static state, the heating and evaporation area of the sample is increased;
The liquid film formed by the force generated by the rotation of the sample effectively suppresses bumping of the sample.
To sum up the above features and its convenient features, the modern rotary evaporator can be used to quickly and gently distill most samples.