Rolf Graeve
The Johns Hopkins University Baltimore, Maryland and George - H. Wahl, Jr. New York University New York
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Kugelrohr Distillation Apparatus
The recent interest in simple distillation equipment' prompted us t o describe a technique first learned by one of us2 (at the Technische Universitat, Berlin-Charlottenburg and now also employed in the laboratories of New York University and The Johns Hopkins University), called "Kugelrohr" distillation (literally "ball tube distillation"). The apparatus illustrated consists fundamentally of a horizontally held glass tube possessing several balllike expansions, for collecting and cooling the distillate, connected to the distilling flask (usually by a T 14/20 ground glass joint) on one end and a vacuum attachment on the other. A windshield wiper motor conveniently produces an oscillating motion and thus eliminates bumping and over-heating. Windshield wiper motors that have an air inlet tube or which have been 80 adapted that they may be operated with compressed air are preferable since this provides a more powerful action than the aspirator vacuum. The still pot is filled t o a fourth or third of flask capacity. An air bath provided with an asbestos plate underneath, a large watch glass as cover, and the holes required for the thermometer and the flask neck is mounted upon a tripod and heated by flame or electrically. This air LOEV,B., SNADER, K.M.,A N D KORMENDY, M. F., J. CHEM. Eouc.,40,426(1963); BEGEMAN, C.R., J. CHEI. EDUC.,40,427 (1963). K. G.
Its temperabath can be maintained to about +2'. ture is about 10-20°C higher than the actual distillation temperature inside the flask when working between 100-200°C. After the distillation, the sample can be recovered from the tube by pouring, washing or applying a refluxing solvent (after changing the flask).
Kvgelrohr distillation apparatus.
Distillations performed with this apparatus are generally nearly quantitative and can be completed within 15-30 min routinely on a semi-micro scale. Depending on the size of the distilling flask and the tubing, amounts of about 50 mg t o 200 g can easily he distilled. Since no rotating seal is used, high vacuum may be applied when dealing with sensitive high boiling compounds. Fractionations can be achieved by changing tubes. This equipment is readily adapted to sublimation and semimicro solvent evaporation.
Volume 41, Number 5, May 1964
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