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Bromination and Debromination of Cholesterol: An Inquiry-Based Lab Involving Structure Elucidation, Reaction Mechanism, and 1H NMR
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Abstract
A classic laboratory experiment involving the bromination of cholesterol and subsequent zinc-mediated debromination back to cholesterol has been reworked for use in an upper-level organic lab. The emphasis has been changed from the purification of cholesterol to a structure determination, conformation, stereochemistry, and mechanism investigation. A series of instructions and questions designed to help the students deduce the structure and three-dimensional shape of dibromocholesterol from approximate 1H NMR data has been developed. Dihedral angles from the three-dimensional perspective drawings and the approximate coupling constants gleaned from 1H NMR data provide the basis for a structural assignment of the dibromocholesterol and allow for a mechanism of bromination to be proposed.
Keywords (Audience):
Upper-Division UndergraduateKeywords (Domain):
Organic ChemistryKeywords (Pedagogy):
Inquiry-Based / Discovery LearningKeywords (Subject):
Mechanisms of ReactionsCiting Articles
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- Received: August 03, 2009
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