A Setup for Bulb-to-Bulb Distillation Bulb-ro-bulb distillahon is olten a eonvmient method for the isolation of milligram to @'am quantities of matend. Cornmercrally avadable equipment for bulb-wbulb discillation (Kugelrohr apparrtus ir expensive and several may be required for teaching labo&ory. In order to distill 0.5-g quantities of material under vacuum in our teaching labs, wehave assemhled the apparatus shown in the figure.
a
The apparatus consists of a 50-mL round-bottom flask, a Kugelrohr receiving flask (available from Aldrich Chemical Co. or constructed by attaching a male ground-glass joint to the bottom of a 50-mL round-bottom flask), and a stopcock adapter, which leads to the vacuum pump. The assembled glassware is held i n a horizontal position by a clamp a t the stopcock end. The distillation flask is heated with a heating mantle and the contents stirred with a small magnetic stir bar. I t is important that all of the distillation flask become warm or the material will only condense off of the top of the flask. Insulation material such as glass wool covered by aluminum foil should cover the top of the flask. The assembly should also occasionally be rotated manually to expose all sides of the distillation flask to the heating mantle. The temDerature mav he monitored by inserting a thermometer under the insulation. Most high-boiling matrrinls will not require coding of rhr rreeivmg flask. Ilowever should rwllng be r r q u r d , a mull container of ice water ur even Dry lceaacrronr mny be placed under the rrcewing flask. Smee bulb-tu-bulb distillation ir a rmple one plate distillation, it docs not separate closely hoilw: matmals. Hawever, solvents and high-boiling tars are readily separated. Yields may be obtained hy weighing the receiving flask before and aRer distillation. Liquid produds may be poured into a container through the male joint end or washed out with solvent. The apparatus may also be used to sublime solids.
M. Mark Midland University of California Riverside, CA 92521
860
Journal of Chemical Education
