This work describes the multi-step synthesis of coumarin and dihydrocoumarin used in our second semester organic lab curriculum.  The target compounds are formed from salicylaldehyde using a Knovenagle condensation followed by lactonization, saponification, decarboxylation and transfer hydrogenation.  The individual steps proceed in high yield and with excellent purity. The synthesis relies on reactions covered in a typical 2nd year organic chemistry lecture course.  During the course of the synthesis, thin-layer chromatography is used to monitor reactions. Extraction, recrystallization. and Column chromatography are used to purify the products. H-1 and C-13 NMR Spectroscopy, IR-Spectroscopy,  Gas-Chromatography and TLC comparison to commercial samples are used to analyze product purity.  Together, all of these factors make the project an excellent review of the techniques covered over the two-semester Organic Chemistry laboratory course. The experiment has received considerable positive feedback from our students who have enjoyed the beautiful sweet vanilla-like smell of the products.

Coumarin and dihydrocoumarin: A new multistep synthesis for the second year organic laboratory

243rd National Meeting (2012)

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