Evaporative separation is not only of great help to students' organic chemistry purification in teaching experiments, but also of great help in real life, such as medicine and liquid diet processing, how to make rotary evaporator machine save separation and purification time to the greatest extent And effective temperature control is a major topic that all colleges and universities are currently exploring. If the device can be improved in experimental teaching, and the temperature and flow rate can be controlled to improve the effect of evaporation and separation, it will have a very large effect on the experimental resources of colleges and universities and the practical ability of students.

 

The improvement of the rotary evaporator kit is applied in the experimental teaching:

The main instruments used are: distillation bottle, heating pot, temperature control table, condenser pipe, discharge valve and frequency converter, etc. The most important part of the configuration of this instrument is the three connections between the condenser pipe and the pressure reducing pump. A piston is connected to the distillation flask. When the system is connected to the atmosphere, the distillation flask and the liquid-contacting flask can be removed to transfer the solution. When the system is connected to the decompression pump, the system is in a decompressed state. This device has a big drawback, that is, when transferring the solution, since the temperature control meter can only read the value at startup, and the value read under the decompression state is very unstable, for example, the set temperature is At (50±5) ℃, the prepared 250 mL solution was evaporated and rotated, but when the heating temperature reached the boiling point close to the solvent, the traditional evaporation configuration instrument could not grasp the purification of organic products. And in the process of the first experiment, many students are often unable to determine whether their experimental results are close to success because of the problem of temperature control.
 
There is also a difficulty in the purification process, that is, during use, because the solution in the bottle is heated, diffused and evaporated in the industrial rotary evaporator flask under negative pressure, the rotary evaporator kit can only be sealed and decompressed at 400~600mm Hg, which leads to Some students who have just started the experiment have no way to distinguish the volume expansion of the solution when configuring the solution, so that the instrument is blocked during the decompression process and the temperature efficiency is too slow. In this way, we can make a self-made temperature sensor so that students can clearly grasp their own industrial rotary evaporator evaporation rate, and can retain the maximum purified product under the condition of ensuring that their solution is configured too much. The distillation flask is set with an arc filter, which can ensure that the students can remove the residue through the arc circulation rotation when configuring, which can greatly improve the evaporation effect.
 

Experimental process and some notes:

During the experiment process, pay attention to the following matters to ensure that the experiment is completed
1. Be sure to turn on the circulating water first, then place the bath pot under the rotating bottle during the heating process, rotate the heating handwheel to raise to the required height, add pure water or thermally conductive silicone oil to 2~3cm below the pot and control the temperature During the indoor operation, to prevent the air flow from being too fast, the rotating flask needs to be cleaned twice during the first experiment, so as to ensure that no other chemicals will appear when the bath is heated.
 
2. Use the sensor that comes with the instrument to record the temperature of the water bath, and use the self-made temperature sensor ABC to control the temperature of the separation liquid. The set value is (50 ± 5) °C. For the first time, the students set the standard configuration for the experiment. 500mL and 1000mL two kinds of flasks, put the solution in separately, work according to the normal requirements, the time will start when the system is balanced, and the difference from usual is that in the first experiment, the separation liquid should be recorded every 10min. temperature. In order to ensure the timing of the completion speed of the experiment
 
3. Compared with the traditional equipment, the vacuum suction hole connecting the self-made temperature sensor and the rotating bottle should be improved, so the pressure should be decompressed before use, and then the motor should be turned on. Falls off during rotation.
 
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