Apparatus for Shori Path Vacuum Distillations Often during the investigation of the products of a reaction, a small amount of slightly volatile liquid is isolated in a mixture with another liquid or solid from which it has to be separated. When the amount of material is very small and when the sample is isolated in a large flask, 250 ml far example, i t is nearly impossible to make a trsnsfer of the material to n commercial short path distillation apparatus and still be able to distill enough sample for meaningful observations. The a p paratns shown in the diagram was constructed in order to allow just such a distillation to he carried out conveniently. A 50-mg sainple of an oily mixture of a liquid and a solid was received in a 250-ml flask after the solvent had been removed from a column chromatographic fraction. The liquid material was shown to distill onto the cold finger of a sublimator probe a t 50°C and lo-' torr. Of course the liquid could not be collected in this manner as i t dripped off. Hence, a Pyrex collection dish was glass blown to the bottom of the cold finger of a sublimator as is shown in the diagram. When this apparatus way inserted into the 250-ml flssk and the vacuum distillation carried out a t 50' and 10-8 torr, a 10-mg sample of the liquid was collected and was shown to have only one component by glc. This is s good separation considering that the solid ',s component wss shown to sublime a t 65'C and 10-' torr. Besides being ve1.y convenient to use, the apparatus shown also allows the distillation of quite nonvolatile liquids as the flask can be heated several centimeters above the collecting dish. Also, there are no deed spaces or cold walls for sample hold up and this allows more of the sample to be collected.
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