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Column chromatography of photosynthetic plant pigments is a common experiment in introductory laboratory courses for science majors and nonscience majors alike. We report a simple, rapid, reproducible, and small-scale solid−liquid extraction of photosynthetic pigments from inexpensive, storebought dried herbs that affords a dark-green extract solution, all of which can be applied directly to a pipet microcolumn made from as little as 0.75 g of silica gel. Carotenes and chlorophylls are cleanly separated using standard steps in microcolumn chromatography: the former elute together within 20 min using gravity and 9:1 (v/v) heptane:EtOAc, and the latter elute together within seconds using air pressure and EtOAc.

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The pharmacologically active lignans sesamin and sesamolin are minor components of sesame oil and ingredients in OTC dietary supplement capsules. We report an introductory undergraduate organic laboratory experiment combining natural product isolation and spectral analysis in which students isolate a mixture of sesamin and sesamolin by either (1) dry column vacuum chromatography (a convenient alternative to flash column chromatography) of commercial sesame oil using an apparatus constructed from common laboratory glassware or by (2) solid−liquid extraction of commercial sesame seed lignan dietary supplement capsules. Two recrystallizations from methanol remove most of the sesamolin to afford crystalline sesamin, which, due to its 2fold rotational symmetry, students can easily identify and characterize by NMR. During a second laboratory period, students perform a 5 min, test tube-scale reaction of sesamin with catalytic BF 3 :OEt 2 to promote its epimerization to episesamin, a diastereomer of sesamin lacking rotational symmetry, and the sesamin/episesamin ratio in the resulting product mixture is established by 1 H NMR integration. Students are asked to propose a mechanism for this epimerization based on their knowledge of the reactivity of benzyl ethers under acidic conditions.

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