The rotary evaporator is mainly used to continuously evaporate a large amount of volatile solvents under reduced pressure conditions. Especially for the concentration of extraction liquid and distillation of the receiving liquid during chromatographic separation, reaction products can be separated and purified. The basic principle of a rotary evaporator is vacuum distillation, which means that under vacuum conditions, when the solvent is distilled, the distillation flask rotates continuously. Structure: The distillation flask is a pear shaped or round bottom flask with a standard ground mouth interface, connected to a pressure reducing pump through a highly reflux serpentine condenser tube, and the other opening of the reflux condenser tube is connected to a receiving flask with a ground mouth, used to receive the evaporated organic solvent. There is a three-way piston between the condenser tube and the pressure reducing pump. When the system is connected to the atmosphere, the distillation flask and the liquid receiving flask can be removed to transfer the solvent. When the system is connected to the pressure reducing pump, it should be in a reduced pressure state. When using, the pressure should be reduced first, and then the electric motor should be turned on to rotate the distillation flask. At the end, the machine should be stopped first, and then the atmosphere should be opened to prevent the distillation flask from falling off during rotation. As a heat source for distillation, it is often equipped with a corresponding constant temperature water bath.
Working principle of rotary evaporator:
By electronic control, the flask is rotated at a constant speed at an appropriate speed to increase the evaporation area. Use a vacuum pump to keep the evaporation flask under negative pressure. The evaporation flask is heated at a constant temperature in a water bath while rotating, and the solution inside the flask is heated, diffused, and evaporated under negative pressure in the rotating flask. The rotary evaporator system can be sealed and depressurized to 400600 millimeters of mercury. The solvent in the distillation flask is heated using a heating bath at a temperature close to the boiling point of the solvent. It can also be rotated at a speed of 50-160 revolutions per minute to form a thin film of solvent and increase the evaporation area. In addition, under the action of an efficient cooler, hot steam can be rapidly liquefied, accelerating the evaporation rate.
The main components of a rotary evaporator are:
1. Rotating motor, which drives the evaporation bottle containing the sample through the rotation of the motor;
2. Evaporation tube has two functions. Firstly, it serves as a sample rotation support axis. Secondly, the sample is sucked out through the evaporation tube and vacuum system;
3. Vacuum system, used to reduce the air pressure of the rotary evaporator system;
4. Fluid heating pots usually heat samples with water;
5. Condensation tube, using double serpentine condensation or other condensing agents such as dry ice and acetone to condense the sample;
6. Condense the sample collection bottle, and after the sample cools down, it enters the collection bottle.
Mechanical or motor-driven mechanical devices are used to quickly lift the evaporation bottle in the heating pot. The vacuum system of the rotary evaporator can be a simple water suction pump immersed in a cold water bath, or a mechanical vacuum pump with a cooling tube. Evaporation and condensation glass components can be simple or complex, depending on the distillation target and the characteristics of the solvent to be distilled. Different commercial devices will contain some basic features, and modern devices usually add functions such as digital control of vacuum pumps, digital display of heating temperature, and even steam temperature.