CHEM237 Lecture 8: CHEM237-11-Ch8-Carbohydrates-partannot.PDF
10 May 2016
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Topics monosaccharides stereochemistry and structure glycosidic bonds other derivatives oligosaccharides disaccharides polysaccharides: storage polysaccharides: starch and glycogen structural polysaccharides: cellulose and chitin glycoproteins glycolipids: monosaccharides. Emil fischer, d- and l- : d- is common form in nature. Glyceraldehyde and dihydroxyacetone are the simplest sugars (trioses) D-or l- : designation determined by stereochemistry at chiral carbon that is furthest away from carbonyl: in linear fischer representation, final chiral c (c*) with. Many stereocenters many isomers enantiomers: mirror images diastereomers: stereoisomers that differ at 1 or more chiral centres and are not enantiomers (so different mpt etc) epimers: differ at only one stereocenter. D-erythrose and d-threose are epimers at c2 (also diastereomers) Addition of 1 c adds a stereo centre. Figure 11-3 to form hemiacetals and (b) ketones to form hemiketals. Intramolecular nucleophilic attack by hydroxyl group at the carbonyl group to make cyclic form of sugar.
