A series of project-based laboratory exercises involving the isolation and purification of two isoflavones from Osage orange was previously reported (Whaley, et. al.,The Chemical Educator, 12:1-6, 2007). These exercises were originally intended for use in the undergraduate chemistry laboratory class. After extensive classroom testing, it has become clear that the previously published exercises are more appropriate for advanced students with an established interest in research. In order to meet the needs of a typical introductory class, the original exercises were extensively modified to reduce the time and effort required to obtain sufficient amounts of purified isoflavones for structural confirmation by spectroscopic methods. Each of the exercises can be completed within 3 to 4 hours by a section of 24 students directed by a single instructor. In Exercise 1, students obtain a sample of powdered Osage orange fruit from which the latex has already been extracted using hexane. The isoflavones are then extracted with ethyl acetate and the students estimate the concentration of the mixture by absorbance. In Exercise 2 the optimum conditions are determined for a separation by thin layer chromatography (TLC). In Exercise 3 a larger scale separation of the isoflavones is achieved using a pre-packed alumina-B cartridge or a miniature column of alumina-B that the students prepare. In Exercise 4 the students observe a demonstration of NMR and/or mass spectrometry and receive copies of spectra of the purified isoflavones for interpretation. The effects of these exercises on student attitudes were measured using questionnaires and statistical results will be presented. (This research was supported financially by the Welch Foundation Departmental Research Program, The Tarleton REAL Program, and an NSF-CCLI Program Award).

Simplified laboratory exercises for isolation of isoflavones from Osage orange with results from classroom testing

247th National Meeting (2014)

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