Chemistry 2223B Lecture Notes - Lecture 9: Stereocenter, Epimer, Sorbitol
10 Feb 2016
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Document Summary
D. reduction to alditols (cid:120) carbonyl groups can be reduced to alcohols by a variety of reducing agents, including catalytic hydrogenation (h2 / metal), nabh4, and lialh4. The formation of enolates destroys stereochemistry at the (cid:68)-carbon. C: epimerization and isomerization (cid:120) example: if any one of d-glucose, d-mannose, or d-fructose is placed in a basic solution, the same equilibrium mixture of all three is formed. 32% (cid:120) epimers are diastereomers that differ in the configuration of any one stereocentre. R (cid:120) isomerization also involves the (cid:68)-carbon, but proceeds through an ene-diol rearrangement. The reaction is a couple of successive tautomerizations. Oh (cid:120) because bendict"s reagent is basic, ketoses will slowly isomerize to aldehydes, which react with the reagent. As a result, ketoses give a false positive test: aldol reactions (cid:120) enolates can attack other aldehydes or ketones in a reaction known as the aldol reaction.
