How Does a Rotary Evaporator Work?

Ⅰ. Working principle of rotary evaporator

Ⅱ.Parts of rotary evaporator

Ⅲ. Working process of rotary evaporator

Ⅳ. Application field of rotary evaporator

Ⅰ. Working Principle Of Rotary Evaporator

Through the steps of heating, decompression, rotation and condensation, the 10L Rotovap realizes the separation and concentration of the liquid mixture. Its working principle is based on the transformation of volatile components from a liquid state to a gaseous state under appropriate temperature and reduced pressure conditions, and then converted back to a liquid state by condensation, and finally collected. This principle makes the rotary evaporator widely used in chemistry, biological science, pharmaceutical and other fields.

Ⅱ.Parts Of Rotary Evaporator

Round bottom flask (Flask):

This is the heart of the rotary evaporator, usually made of heat-resistant glass. The liquid mixture was charged into a round bottom flask for distillation.

Rotor :

The rotor is a rotating part used to load the round bottom flask, usually made of metal or chemically resistant material. It is driven by an electric motor to make the round bottom flask rotate on a horizontal plane.


The condenser is located on the top of the rotary evaporator and is used to cool the evaporated gas to convert it into a liquid. Condensers are usually made of glass and contain pipes for a coolant, such as cold water or coolant, inside.

Heating System:

In order to control and provide the proper heating temperature, the rotary evaporator is equipped with a heating device, usually a heated water bath or a heated oil bath. The heating device transfers thermal energy to the round bottom flask by conducting heat, causing the volatile components in the mixture to evaporate.

Vacuum System:

In order to reduce the boiling point of the evaporating liquid, the rotary evaporator is usually equipped with a vacuum system. The decompression device can be a vacuum pump or a water dust pump, which is used to reduce the pressure in the flask to facilitate the evaporation of volatile components.

Collection Flask:

In the condenser, the gas is cooled and converted to a liquid, which is then collected in a bottle or container, often called a collection flask. Collection bottles are used to collect and store the volatile components separated after evaporation.

how doesa rotary evaporator work component

Ⅲ. How Does a Rotary Evaporator Work?


Heating is a critical step in a rotary evaporator, providing energy to evaporate volatile components in a mixture. The liquid in the flask can be heated by means of a heating device, such as a heated water bath or a heated oil bath. The heating unit provides a constant temperature to bring the mixture to the desired evaporation temperature. Controlling the heating temperature is important to ensure efficient evaporation of volatile components and to control the rate of the reaction.

Stress reliever:

The pressure in the flask can be reduced by means of a pressure reducing device, such as a vacuum pump or a water dust pump. The purpose of decompression is to lower the boiling point of a liquid, making it easier for volatile components to evaporate. By reducing the pressure, volatile components can be evaporated at relatively low temperatures, reducing the effect of heat on non-volatile components, resulting in more selective separations.

Evaporation process:

Under the right conditions of temperature and reduced pressure, the volatile components begin to change from a liquid state to a gaseous state. Heating and decompression enable the molecules in the liquid to overcome the surface tension, fully volatilize into a gas, and enter the condenser of the rotary evaporator through the opening of the flask. The efficiency and selectivity of the evaporation process depends on the heating temperature, the degree of reduced pressure, and the nature of the liquid mixture.


In the condenser, the vaporized gas is rapidly cooled by circulation of a coolant such as cold water or cooling liquid, thereby turning it into a liquid. The condenser is usually made of glass and contains pipes for the coolant inside. As the gas passes through the condenser, coolant flows through the tubes, removing heat and causing the gas to condense into a liquid. In this way, the liquid in the condenser can be collected into the collection bottle.

Ⅳ. Application Field Of Rotary Evaporator

A. Laboratory application:

Rotary evaporators are used in a wide variety of laboratories, especially in the chemical and biological sciences. The following are common applications of rotary evaporators in the laboratory:

Solvent removal:

Rotary evaporators are widely used to remove solvents from compounds, allowing samples to be concentrated and purified. This is very common in organic synthesis, pharmaceutical research and extraction of natural products.

Reaction control:

Rotary evaporators can be used to monitor and control volatile components during reactions. By timely removing the solvent or by-products in the reaction, the reaction equilibrium and the improvement of the yield can be promoted.

how does a rotary evaporator work

Solvent recovery:

Rotary evaporators can be used to recover and reuse solvents. By evaporating and collecting the solvent, solvent recovery and environment-friendly laboratory operation can be realized.

Sample Concentration:

Rotary evaporators can be used to concentrate large volumes of liquid samples into smaller volumes for subsequent analysis and detection, such as mass spectrometry, chromatography, etc.

Solvent exchange:

Rotary evaporators can be used to transfer samples from one solvent to another. By adjusting the temperature and decompression conditions, the evaporation and exchange of the solvent can be promoted, so as to realize the conversion of the solvent.

how does a rotary evaporator work

B. Industrial application:

Rotary evaporators are also widely used in industry. Here are some applications of rotary evaporators in industries such as pharmaceuticals, food and fragrances:

Pharmaceutical industry:

Rotary evaporators can be used for drug concentration, solvent recovery and purification in the pharmaceutical process. It can be used to prepare pharmaceutical raw materials, intermediates and end products.

Food industry:

Rotary evaporators have a variety of applications in food processing. For example, it can be used to remove solvents from food, concentrate fruit juices and extract natural flavors.

how does a rotary evaporator work

Fragrance and fragrance industry:

Rotary evaporators can be used to extract flavor and fragrance components from natural plants. It can help isolate and concentrate aromatic compounds for use in the production of perfumes, flavorings and fragrances.

Chemical industry:

Rotary evaporators are widely used in the chemical industry. It can be used for solvent recovery, compound purification, solvent exchange, and solvent removal during organic synthesis.

How Does a Rotary Evaporator Work?

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