Notes on distillation
During the distillation operation, the following points should be noted:
(1) Control the heating temperature. If a heating bath is used, the temperature of the heating bath should be several degrees higher than the boiling point of the distilled liquid, otherwise it will be difficult to distill the distillate. The more the heating bath temperature is higher than the boiling point of the distilled liquid, the faster the distillation speed. However, the temperature of the heating bath should not be too high, otherwise it will cause the vapor pressure of the distillation flask and the upper part of the condenser to exceed atmospheric pressure, which may cause accidents, especially when distilling low-boiling substances. In general, the temperature of the heating bath cannot be higher than the boiling point of the distilled material by 30°C.
(2) When distilling a high-boiling substance, it is easy to be condensed, and the steam is often condensed before reaching the side tube of the distillation flask and dripped back into the distillation flask. Therefore, short-necked distillation flasks should be used or thermal insulation measures should be taken to ensure the smooth progress of distillation.
(3) Before distillation, the boiling point and saturated vapor pressure of the distilled chemical reagent and its impurities must be understood to determine when (ie, at what temperature) the purification reagent is collected.
(4) Round bottom flasks should be used for distillation flasks.