Perkin triangle
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| Perkin triangle | |
 A Perkin triangle distillation setup
1 Stirrer bar/anti-bumping granules
2 Still pot 3 Fractionating column, preferably vacuum jacket insulated 4 Thermometer 5 Teflon tap 1, distillate collecting tap 6 Cold finger 7 / 8 Cooling water outflow/inflow 9 Teflon tap 2, still isolation tap 10 Vacuum/gas inlet 11 Teflon tap 3, distillate isolation tap 12 Still receiver |
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| Uses | Distillation |
|---|---|
| Inventor | William Henry Perkin |
| Related items | Vacuum distillation |
A Perkin triangle is a piece of specialist distillation apparatus. It was invented by William Henry Perkin, when presumably it was triangular in shape.[citation needed] The image opposite shows a more modern version 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.
[edit] Solvent drying
A Perkin triangle is also a convenient device for drying solvents. The solvent can be allowed to relux over a drying agent housed in the still pot (shown as 1 in the figure) for a suitable time to affect the drying of the solvent. The collecting tap (shown as 5 in the figure) can then be opened to collect the solvent in a schlenk flask for storage. Depending on the boiling point of the solvent a vacuum can be applied.
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