From the beginnings of the ancient alchemists to today's modern research,
the principles behind simple laboratory distillation apparatus have hardly changed.
What is a rotary evaporator?
A rotary evaporator is a specially designed instrument for the evapora- tion of solvent (single-stage or straight distillation) under vacuum. The evaporator consists of a heating bath with a rotating flask, in which the liquid is distributed as a thin film over the hot wall surfaces and can evaporate easily. The evaporation rate is regulated by the heating bath temperature, the size of flask, the pressure of distillation and the speed of rotation.
Functional principle of a rotary evaporator
Advantages of the rotary evaporator (compared with static apparatus)
With a vacuum rotary evaporator you can carry out single-stage distilla- tion runs quickly and gently.
The evaporation capacity of a rotary evaporator is about 4 times greater than that of a conventional, static distillation apparatus. Heat transmission in the heating bath as well as inside the flask is greatly improved by rotation of the evaporating flask. Rotation greatly enlarges the active surface inside the flask, hastening the evaporation. With the liquid remaining at any one point of the flask wall for a short time only, it is subject to minimum stress during the distillation (no overheating, no incrustation). Bumping and foaming are greatly reduced by the rotation.
Rotary evaporators are used for:
- Distillation of solvent
- Concentration of solutions and suspensions Crystallization or recrystallization
- Synthesis and purifying of fine chemicals Soxhlet extraction
- Powder and granules drying
- Recycling of solvent