Instead of directly heating the reaction solvent, the rotary evaporator transfers heat through the bath pot, making the heating more uniform and the temperature easier to control. Water, oil and sand are commonly used as the heating medium.
The container of the rotary vaporizer should be preheated before heating. When the glass is suddenly exposed to high or low temperature, it often explodes due to the rapid rise of temperature and uneven heating. Therefore, the container must be preheated before the test, that is, the container must be placed in the heating medium to make its temperature rise slowly or cool slowly, so that the glass is evenly heated.
The water bath method takes water as a hot bath substance, and puts the reaction vessel in water to heat water. Because the water temperature can reach 100 ℃ at the standard atmospheric pressure, the maximum temperature of the water bath can only reach 100 ℃. The method of treating container products by water bath is: immerse the reaction container into the bath pot containing water. The container cannot be in direct contact with the wall of the bath pot. Use electric heating or other heating methods to heat the water to an appropriate temperature and conduct the temperature into the reaction container.
Oil bath is similar to water bath, which is to change oil with water. Commonly used are soybean oil, cottonseed oil, etc. The temperature is higher than that of the water-based oil bathtub, generally between 100 ℃ and 250 ℃. The operation method of the oil bathtub is the same as that of the water bathtub, but the operation of the oil bathtub must be careful to prevent the oil from overflowing or the temperature of the oil bathtub is too high, resulting in a fire, and the rotating speed of the rotating bottle should be controlled to rise slowly, so as to prevent the oil from splashing out and causing harm to the experimenter.
Sand bath method is to bury the reaction tank in sand and heat the sand tank with infrared ray, which is more uniform. Due to the poor thermal conductivity of sand and rapid heat dissipation, the sand layer at the contact between the bottom of the container and the sand bath should be thinner. The temperature of sand bath is usually above 260 ℃.
