Resumen de Radial Chromatography for the Separation of Nitroaniline Isomers
Robert B. Miller, William S. Case
Separation techniques are usually presented in the undergraduate organic laboratory to teach students how to purify and isolate compounds. Often the concept of liquid chromatography is introduced by having students create “silica gel columns” to separate components of a reaction mixture. Although useful, column chromatography can be a laborious technique for students to perform. The separation efficiency can be compromised if students do not prepare the column correctly, and the time required to separate substances can extend beyond a typical laboratory period. Herein, the use of radial chromatography (centrifugal thin-layer chromatography) as an alternative to the traditional column chromatography technique utilized in many teaching laboratories is discussed. Radial chromatography can be used to introduce the principles that underlie liquid chromatography, with the added benefit of providing a relatively fast and highly efficient separation. An experiment for the efficient separation of a mixture containing 2-nitroaniline and 3-nitroanilne using radial chromatography is presented. Typical student results show that each substance can be collected with a high percent recovery (∼70–80%). Furthermore, the melting range of each isolated substance is found to be in agreement with literature values. The separation can be completed in 40–50 min once the sample has been loaded.
