How Does a Rotary Evaporator Work?

A 10l rotovap is a common laboratory instrument used to separate and recover liquid solvents. It uses the principle of evaporation and condensation to separate the solvent from the solution and recover it for reuse.

During the evaporation process, the vacuum pump creates a negative pressure environment that lowers the boiling point of the solvent, causing it to evaporate at a lower temperature. The solvent vapor passes through the condenser, where it is cooled and converted to liquid form. In this way, the solvent can be collected from the condenser and recycled.

Components Of a Rotary Evaporator:

A. Flask: The sample to be evaporated is placed in a round bottom flask, usually made of glass, which is securely attached to a rotary evaporator.

B. Rotary Drive: The rotary drive rotates the flask, ensuring maximum exposure of the sample to the evaporating solvent.

C. Heating Bath: The heating bath provides controlled and consistent heating to the flask, increasing the temperature of the sample and facilitating the evaporation process.

D. Vacuum system: The vacuum system reduces the pressure inside the evaporator and lowers the boiling point of the solvent, thereby achieving efficient evaporation at a lower temperature.

E. Condenser: The condenser cools the evaporated solvent vapor so that it condenses back into a liquid form, which can be collected separately.

F. Collection bottle: Condensed solvent is collected in a separate bottle for easy separation from the sample.

how does a rotary evaporator work

How Does a Rotary Evaporator Work?


The round-bottomed flask containing the sample is securely attached to the rotary evaporator. The flask is typically made of glass and has a tight seal to prevent leakage.

Vacuum Setup:

The vacuum system of the rotary evaporator is engaged. This creates a low-pressure environment within the system, lowering the boiling point of the solvent and facilitating evaporation at lower temperatures.


The heating bath, located below the flask, is set to the desired temperature. The heating bath provides controlled and consistent heating to the flask, raising the temperature of the sample.


The rotary drive, also known as the motor, spins the flask at a controlled speed. The rotation causes the sample to spread out thinly on the inner surface of the flask, maximizing the surface area exposed to the heated solvent.


As the flask rotates, the heated solvent in the sample begins to evaporate. The reduced pressure within the system further lowers the boiling point of the solvent, allowing it to evaporate at a lower temperature than its normal boiling point.

Vapor Pathway:

The evaporated solvent forms vapor that rises through the flask towards the condenser. The vapor path is facilitated by the reduced pressure created by the vacuum system.


The vapor reaches the condenser, which is typically a coil that is cooled by circulating coolants, such as water or liquid nitrogen. The cooling of the condenser causes the solvent vapor to condense back into liquid form.


The condensed solvent drips down from the condenser into a separate collection flask. This allows for easy separation of the solvent from the sample. The sample remains in the original flask.


Once the evaporation process is complete, the rotation is stopped, and the vacuum is released. The flask can be removed from the rotary evaporator, and the collected solvent can be retrieved for further analysis or disposal.

Application Case 1: Natural Product Extraction

Rotary evaporators are commonly used in natural product chemistry to remove solvents from plant extracts, essential oils, or other natural samples to obtain pure compounds. This extraction process is based on differences in the solubility of the chemical constituents of natural products in different solvents.

First, the natural sample is mixed with an appropriate solvent in which the target compound is dissolved. Then, the mixture was placed in a rotary evaporator, and the solvent was removed through a process of heating and evaporation. Due to the large surface area provided by the rotary evaporator, the sample is evenly distributed over the inner surface of the flask, resulting in faster evaporation.

The solvent vapor is cooled by a condenser and converted to liquid form. In this way, the target compound can be collected from the condenser into a container without large amounts of solvent. This process helps to remove excess solvent, making the extracted compounds purer.

Natural product extraction can use a single solvent or a mixture of solvents, depending on the identity of the target compound. Selection of an appropriate solvent system is critical for extraction of desired compounds. Rotary evaporators provide a fast, efficient and controlled way to extract compounds of interest from complex natural mixtures and obtain purer compounds.

Application Case 2: Solvent Recovery

When it comes to solvent recovery, rotary evaporators have a wide range of specific applications in the laboratory and industry.

Organic Synthesis:

In organic synthetic chemistry, a large amount of organic solvents are required as reaction media and solvents. These solvents are expensive and are generally considered waste after their use. A rotary evaporator can be used to recover these organic solvents, separate them from the reaction mixture, and reuse them. Through the process of evaporation and condensation, solvents can be collected and reused after proper treatment, saving costs and reducing environmental impact.

Analysis experiment:

In analytical experiments, various solvents are used to prepare samples and standard solutions. These solvents are often expensive and tend to become waste after the experiment is complete. Through the rotary evaporator, these solvents can be recovered and reused, thereby reducing the cost of experiments.

Solvent library management:

In drug discovery and high-throughput synthesis, it is often necessary to use a large number of different solvents. Using a rotary evaporator can recover solvents, centrally manage them, and ensure their re-use. This effective solvent library management increases laboratory efficiency and reduces solvent procurement and waste disposal costs.

Industrial production:

In industrial production, many chemical processes require the use of large amounts of solvents. Solvent recovery is a key step to reduce production costs and reduce environmental pollution. Rotary evaporators allow efficient solvent recovery on an industrial scale, separating solvents from wastewater or reaction mixtures for reuse.

Environmental protection application:

Solvent recovery is an important aspect of environmental sustainability. By recovering solvents with a rotary evaporator, you can reduce the demand on natural resources, reduce solvent consumption, reduce waste generation, and reduce negative impact on the environment.

How Does a Rotary Evaporator Work?

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