Perkin triangle

Infobox Laboratory equipment
name = Perkin triangle

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caption =

A Perkin triangle distillation setup

nowrap|1 Stirrer bar/anti-bumping granules nowrap|2 Still pot nowrap|3 Fractionating column, preferably vacuum jacket insulated nowrap|4 Thermometer nowrap|5 Teflon tap 1, distillate collecting tap nowrap|6 Cold finger nowrap|7 / 8 Cooling water outflow/inflow nowrap|9 Teflon tap 2, still isolation tap nowrap|10 Vacuum/gas inlet nowrap|11 Teflon tap 3, distillate isolation tap nowrap|12 Still receiver

acronym =
other_names =
uses = Distillation
inventor = William Henry Perkin
manufacturer =
model =
related = Vacuum distillationA Perkin triangle is a piece of specialist distillation apparatus. It was invented by William Henry Perkin, when presumably it was triangular in shape.Fact|date=March 2008 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 allow 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.

Solvent drying

A Perkin triangle is also a convenient device for drying solvents. The solvent can be allowed to reflux 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.