BIOC 2580 Lecture Notes - Lecture 12: Anomer, Pyranose, Furanose
11 Jun 2016
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Document Summary
The oh group at c-5 reacts with the carbon atom of the aldehyde group to form a stable six- membered ring. This renders c-1 asymmetric giving rise to two stereoisomers and . These isomeric form that differ only in their configuration around the hemiacetal or hemiketal carbon are called anomers. Follows the same theme as for an aldose. The electrophilic carbonyl carbon atom reacts with the nucleophilic o of an oh group. Solid glucose is found either in the or the form of the hemiacetal. When dissolved in water, it slowly converts into an equilibrium mix of the , and linear forms. With time, a solution of -d-glucose and a solution of -d-glucose form identical equilibrium mix with identical optical properties (qpprox. Composition 1/3 -d-glucose, 2/3 -d-glucose and trace amounts of the linear form. When sugars cyclize the form one of two ring forms: pyranose (6-membered) or furanose (5- membered)
