Kugelrohr

A Kugelrohr (literally "ball tube") is a short path vacuum distillation apparatus typically used to distill relatively small amounts of high boiling (> 300 °C) compounds under greatly reduced pressure in the laboratory.

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Design

Short path refers to the short distance that the vapors of the distillate needs to travel, which helps reduce losses, and speed up collection of the distillate. Distilling under vacuum is used to prevent the compound being distilled from charring due to atmospheric oxygen, as well as to allow the distillation to proceed at a lower temperature^{[1] [2]}.

The apparatus consists an electric heater with a digital thermostat, and two or more bulbs connected with ground glass joints. The compound to be distilled is placed in the last bulb. The other bulbs can be used to collect the distillates sequentially; when they are collecting the desired fraction, the bulb is cooled with ice to aid condensation. A motor drive is used to rotate the string of bulbs to reduce bumping and give efficient distillation.

References

1. ^ Kugelrohr Distillation Apparatus at Sigma-Aldrich accessed 8 Sep 2006
2. ^ Kugelrohr Distillation Apparatus at Buchi company accessed 15 Nov 2006