How to Use Rotary Evaporator?

The rotary evaporator is the essential tool that I use in every organic laboratory all over the world. However, it primarily removes the solvent from the sample through evaporation under reduced pressure. Reduced pressure in the mini rotary evaporator causes the solvent to boil at a very lower temperature than normal. Remember that rotating the round bottom flask on creases the surface area of the liquid and so the rate of evaporation. The solvent vapor travels into the cooler water condenser, condensing and dripping into the separate receiving flask. It is the solvent removal process, leaving a concentrated compound in the original round bottom flask. In this short guide, you will learn How to Use Rotary Evaporator? So, let’s start.

General Rules to Use Rotary Evaporator:

The introduction of the vacuum lets greater distillation capacity. Boiling points and system pressure are codependent, and system pressure and water temperature are adjusted to give the appropriate boiling point temperature. As the pressure lowers, the evaporation solvent could exceed the condensation capacity of the evaporator, which causes unnecessary solvent loss. Here is a complete process of using a mini rotary evaporator.

First, you need to remove the round bottom flask from the condenser’s base, which is placed directly above the hot bath. Ensure your flask is clean before use to prevent accidentally mixing incompatible chemicals. The round bottom flask with the sample is placed on the mini rotary evaporator. If need be, use vacuum grease, which is located next to the rotary evaporator, this will help you to create a vacuum seal between the condenser and the flask. Use a Keck clamp to secure your flask to the condenser.

Check the collection flask to the left of the hot bath and below the condenser. Inspect the flask to make sure t is clean. Open the cabinet doors directly below the mini rotary evaporator. Since the chiller is turned sideways, on the right side of the cabinet is the back, and the front of the chiller is on its left side. Ensure the tubing is securely connected to the back of the chiller and the condenser. After that, turn on the chiller and fill the water in the condenser.

Set the required temperature and ensure that the vacuum pump is connected to the condenser. Additionally, don’t forget to turn off the release valve. Please turn on the vacuum and fill the hot bath with enough water so the round bottom flask is securely sitting on it. In addition, turn on the hot bath and use the dial to set the temperature of it. It is time to turn on the mini rotary evaporator. Using the dial, set the desired spin speed of the condenser. Once you have made all the specifications, press the dial, and t will start rotating. The solvent should start collecting on the condenser and drop down into the receiving flask.

After all the solvent is evaporated, the vacuum is released, your flask is raised out of the water bath, and the spinning is automatically discontinued. Turn off the mini rotary evaporator and a hot bath, and ensure the temperature dial is set to 0. At last, turn off the chiller and vacuum pump and slowly open the system by rotating the release valve. Remove the round bottom flask from the condenser after it completely cools down. Also, remove the product from it. Moreover, remove the collection flask and the product from it.

Why Use Rotary Evaporation?

Rotary evaporation is often used to remove solvents with relatively low boiling points. The reason is that rotavap is very simple to use and relatively very quick to remove the solvent, which mostly depends on the volume and solvent. The mini rotary evaporator is found in most organic laborites of the world and is more efficient than evaporation under atmospheric pressure. However, solvents such as water with relatively very high boiling points are very hard to remove with standard rotary evaporators, so they need a vacuum system capable of getting sufficient low pressure. Therefore, water is often removed before putting any sample on a rotavap, using drying agents.


Above, we share a complete guide on how to use rotary evaporation. However, the mini rotary evaporator is used to vacuum distillation to evaporate the solvent from raw materials. Usually, a cold finger condenser is attached to the solvent trap, which sits opposite the flask on the rotator unit. The cold water in the condenser builds a zone of cooling. On the other hand, the boiling flask encourages evaporation. At the same time, the solvent trap is often cooled to discourage evaporation. So, trapping volatile compounds once they have started to accumulate in a liquid phase.

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