Kugelrohr distillation unit

Since it may undergo reaction with benzaldehyde in the subsequent step to give benzaldehyde azine, it is advisable to remove the last traces of hydrazine by rotating the flask under reduced pressure. The submitters used an oscillating motor which operates on compressed air or vacuum and is commonly employed with Kugelrohr distilling units. One such motor is available from the Aldrich Chemical Company, Inc. 

These latter pieces of equipment may be called bulb-to-bulb distillation units. A commercial form is the Kugelrohr apparatus (Aldrich). The material to be distilled is placed in a suitably sized round-bottomed flask (one-third full) and attached to the receiver flask train (Fig. 2.120). This arrangement is connected to a horizontal drive shaft which enables the bulbs to be gently rocked by a safe air-or vacuum-operated oscillating motor, which speeds distillation and prevents bumping. The distillation flask may be heated up to 225 °C in an i.r.-radiant heater. The hollow drive shaft may be connected to a vacuum pumping system and the apparatus operates down to 1 x 10 5mmHg. 

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