Use And Functions Of The Rotavapor

November 3, 2021

A rotary evaporator or rotary evaporator is a device used for the removal or recovery of solvents at low pressure.

A rotary evaporator (or rotary evaporator / rotary evaporator) is a device used in chemical laboratories for the efficient and gentle removal of solvents from samples by evaporation. When referenced in the chemical research literature, the description of the use of this technique and equipment may include the phrase “rotary evaporator”, although the use is often indicated in other language (for example, “the sample evaporated under pressure reduced ”).

Rotary evaporators are also used in molecular cooking for the preparation of distillates and extracts.

Table of Contents


A common basic operation in the Organic Chemistry laboratory is the removal of a volatile organic solvent from a reaction mixture or a process such as liquid-liquid extraction. Although this operation, in principle, could be carried out by simple distillation, the fastest and most convenient method is the use of a  rotary evaporator  for distillation under reduced pressure.

It basically consists of an electric motor, which causes the rotation of a tube attached to a ground glass joint guide tube. A round bottom flask containing the solution is attached to the latter. This flask is partially immersed in a  water bath , maintaining rotation. The bath temperature should not exceed 35–40 ° C for handling the most common organic solvents. Next to the system is a  coolant  that circulates a liquid (water or antifreeze). This produces condensation of the solvent, which is recovered in a collector. The set is a closed system connected to a  vacuum intake  (vacuum pump, water pump or vacuum circuit).

How to use

  • A round bottom flask is placed with the mixture that we want to evaporate the solvent, filling it at most to half its capacity.
  • Check that both the collector and the evaporator tube are clean, since if the collector contains a solvent of less than the one to be eliminated, the evaporation process slows down.
  • Turn on the vacuum system, closing the air valve with the outside, and check by hand that there is vacuum in the guide tube.
  • Lift the assembly using and attach the flask to the ground-glass mouth of the guide tube, holding with a clamp to prevent it from falling into the water bath.
  • Open the coolant water intakes.
  • Immerse the flask partially in the water bath and start the motor that rotates the flask. Adjust the speed of the rotation so that there is no projection of the liquid from the flask into the guide tube.
  • Connect the vacuum source and close the valve that communicates the system with the outside.
  • By actuating the jack, lower the assembly until the distillation flask is partially submerged in the water bath.
  • Turn on the bath heating and heat to the minimum temperature necessary to achieve evaporation of the solvent.
  • Continue the distillation until no more condensation of vapors is observed in the manifold and the volume of the contents of the distillation flask no longer decreases.
  • Lift the assembly until the flask is removed from the water bath.
  • Disconnect the vacuum intake first, then open the air cock with the outside.
  • Stop the motor and remove the distillation flask from the mouth of the guide tube with rotary movements.
  • Close the vacuum intake and the coolant water, and turn off the bathroom heating.
  • Empty the contents of the collector and check that the guide tube is clean. If the tube is dirty, wash it with acetone.
Dr. Loony Davis5
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Born and raised in Brussels in an English family, I have always lived in a multicultural environment. After several work experiences in marketing and communication, I came to Smart Water Magazine, which I describe as the most exciting challenge of my career.
I am a person with great restlessness and curiosity to learn, discover what I do not know, as well as reinvent myself daily, someone who is curious about life and wants to know. I enjoy sharing knowledge.
This is my personal project but I also collaborate in other blogs, it is the case, the most important web on water currently exists in the US, if you are interested you can read my articles here.

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