A Perkin triangle is a specialized apparatus for the

distillation Distillation, or classical distillation, is the process of separating the components or substances from a liquid mixture by using selective boiling and condensation, usually inside an apparatus known as a still. Dry distillation is the he ...

of air-sensitive materials. It is named after William Henry Perkin Jr., whose design was approximately

triangular A triangle is a polygon with three edges and three vertices. It is one of the basic shapes in geometry. A triangle with vertices ''A'', ''B'', and ''C'' is denoted \triangle ABC. In Euclidean geometry, any three points, when non- collinea ...

. The diagram shows a more modern version, in which the glass taps have been replaced with more air-tight

Teflon Polytetrafluoroethylene (PTFE) is a synthetic fluoropolymer of tetrafluoroethylene that has numerous applications. It is one of the best-known and widely applied PFAS. The commonly known brand name of PTFE-based composition is Teflon by Chemo ...

taps. Some compounds have high boiling points and are sensitive to air. A simple

vacuum distillation Vacuum distillation is distillation performed under reduced pressure, which allows the purification of compounds not readily distilled at ambient pressures or simply to save time or energy. This technique separates compounds based on differences i ...

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" adapter 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 uses 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, so that the reflux may continue. To do this, the sample is first isolated from the vacuum through the taps. The vacuum over the sample is then replaced with an inert gas such as nitrogen or argon. The collection vessel or still receiver can then be removed and stoppered. Finally, a fresh collection vessel can be added to the system, evacuated, and linked back to the distillation system through the taps to collect the next fraction. The process is repeated 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 2 in the figure) for a suitable time to dry 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.

Reference textbook

External links

Royal Society of Chemistry: Classic Kit: 'Perkin's' triangle

{{DEFAULTSORT:Perkin Triangle Distillation Laboratory equipment Laboratory glassware