A distillation flask is an eggplant shaped or round bottom flask with a standard ground mouth interface, connected to a pressure reducing pump through a highly reflux serpentine condenser tube. 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 distillation flask should be stopped first and then vented to prevent it 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 400-600 millimeters of mercury; Heat the solvent in the distillation flask with a heating bath at a temperature close to the boiling point of the solvent; At the same time, it can also rotate 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.
Instructions for using a rotary evaporator:
1. Turn on the low-temperature coolant circulation pump. Pay attention to pressing the power button and then the cooling button, and turn on the cycle after reaching the desired temperature.
2. Turn on the water pump to circulate water.
3. Install the distillation flask and secure it with a clamp. Turn on the vacuum pump and wait for a certain amount of vacuum before starting to rotate.
4. Adjust the height and rotation speed of the distillation flask, and set the appropriate water bath temperature.
5. After steaming, stop rotating first, then let the atmosphere flow, stop the water pump, and then remove the distillation flask.
Stop the low-temperature coolant circulation pump, stop the water bath heating, turn off the water pump circulation water, pour out the solvent in the receiving bottle, clean the buffer ball, and receive the bottle.
Precautions for using a rotary evaporator:
1. When using, first draw a small vacuum (about 0.03MPa), then turn on the rotation to prevent the distillation flask from slipping off; When stopping, first stop the rotation, hold the distillation flask with your hand, let it breathe, and wait for the vacuum degree to drop to around 0.04MPa before stopping the vacuum pump to prevent the distillation flask from falling off and being sucked back.
2. Each interface, sealing surface, sealing ring, and joint need to be coated with a layer of vacuum grease before installation
Before powering on the heating tank, water must be added and dry burning without water is not allowed
4. If the vacuum degree is too low, pay attention to checking the airtightness of all joints, vacuum tubes, and glass bottles.
5. When rotary steaming sensitive substances to air, connect a nitrogen balloon to the exhaust port, first pass a burst of nitrogen gas to exhaust the air inside the rotary evaporator, and then connect the sample bottle for rotary steaming. After steaming, release nitrogen gas to increase the pressure, then turn off the pump, and remove the sample bottle and seal it.
If the viscosity of the sample is high, the rotation speed should be slowed down and manually rotated slowly to form a new liquid level that is conducive to solvent evaporation.