ERIC Number: EJ1079291
Record Type: Journal
Publication Date: 2015-Oct
Abstractor: As Provided
Nature's Treatment for Irritable Bowel Syndrome: Studies on the Isolation of (-)-Menthol from Peppermint Oil and Its Conversion to (-)-Menthyl Acetate
Egan, Maeve; Connors, E´ilis Margaret; Anwar, Zeeshan; Walsh, John J.
Journal of Chemical Education, v92 n10 p1736-1740 Oct 2015
A simple, robust, and reproducible method was developed for the isolation of (-)-menthol from peppermint oil and to study the effect of different types of leaving groups, catalysts, solvents, and tertiary base on the extent of esterification of (-)-menthol to (-)-menthyl acetate. In this experiment, students compare leaving group properties of acetate and chloride ions from the acylating reagents acetic anhydride and acetyl chloride, respectively. The extent of conversion is compared when pyridine and 4-(dimethylamino)pyridine are used as catalysts, when "N,N"-diisopropylethylamine is used as tertiary base, and when the solvent is changed from dichloromethane to diethyl ether to "N,N"-dimethylformamide. Students are assessed on the chromatographic/spectroscopic purity and yield of (-)-menthol isolated and on their understanding of the factors that affect its extent of conversion to (-)-menthyl acetate. Full spectral characterization of both compounds is also conducted. They also complete a series of answers to questions based on lecture material presented on this topic, complete a crossword as a formative assessment tool, and are required to present a PowerPoint slide to their peers on a particular aspect of the bench to bedside development of peppermint oil for the treatment of irritable bowel syndrome.
Descriptors: Diseases, Drug Therapy, Science Instruction, Pharmacology, Undergraduate Study, College Science, Organic Chemistry, Cooperative Learning, Hands on Science, Medicine, Spectroscopy, Plants (Botany), Laboratory Experiments
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Publication Type: Journal Articles; Reports - Descriptive
Education Level: Higher Education; Postsecondary Education
Authoring Institution: N/A