Perkin triangle
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1: Stirrer bar/anti-bumping granules 2: Still pot 3: Fractionating column 4: Thermometer/Boiling point temperature 5: Teflon tap 1 6: Cold finger 7: Cooling water out 8: Cooling water in 9: Teflon tap 2 10: Vacuum/gas inlet 11: Teflon tap 3 12: Still receiver
Perkin triangle a piece of specialist distillation apparatus invented by William Perkin FRS, and which was presumably originally triangular in shape. The image right is a more modern version of the device in which the glass taps have been replaced with more air-tight Teflon taps.
Some compounds have high boiling points as well as being air sensitive. A simple vacuum distillation system can be used, whereby the vacuum is replaced with an inert gas after the distillation is complete. However, this is a less satisfactory system if one desires to collect fractions under a reduced pressure. To do this a "pig" adaptor can be added to the end of the condenser, or for better results or for very air sensitive compounds a Perkin triangle apparatus can be used.
The Perkin triangle, has means via a series of glass or Teflon taps to allows fractions to be isolated from the rest of the still, without the main body of the distillation being removed from either the vacuum or heat source, and thus can remain in a state of reflux. To do this, the sample is first isolated from the vacuum by means of the taps, the vacuum over the sample is then replaced with an inert gas (such as nitrogen or argon) and can then be stoppered and removed. A fresh collection vessel can then be added to the system, evacuated and linked back into the distillation system via the taps to collect a second fraction, and so on, until all fractions have been collected.
Please note, any distillation procedure is extremely hazardous, and so the use of a Perkin triangle should only be entered into by a person skilled in the use of vacuum distillation apparatus and the use of a vacuum/gas manifold, and under the supervision of somebody already very familiar with these techniques.
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Principles: Raoult's law, Dalton's law, Reflux, Fenske equation
Industrial processes: Batch distillation, Continuous distillation
Laboratory methods: Rotary evaporator, Kugelrohr, Spinning band distillation
Techniques: Fractional distillation, Vacuum distillation, Extractive distillation, Reactive distillation, Dry distillation, Destructive distillation, Azeotropic distillation, Steam distillation
