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Lecture Organic chemistry: Chapter 23 - L. G. Wade, Jr.

Chapter 23 introduce to carbohydrates and nucleic acids. After completing this chapter, students will be able to: Draw and identify the structures of glucose, its anomers, and its epimers, as Fischer projections and as chair conformations; correctly name monosaccharides and disaccharides, and draw their structures from their names; predict the reactions of carbohydrates in acidic and basic solutions, and with oxidizing and reducing agents;. | Chapter 23 Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. Carbohydrates and Nucleic Acids Chapter 23 Carbohydrates Synthesized by plants using sunlight to convert CO2 and H2O to glucose and O2. Polymers include starch and cellulose. Starch is a storage unit for solar energy. Most sugars have formula Cn(H2O)n, “hydrate of carbon.” Chapter 23 Classification of Carbohydrates Monosaccharides or simple sugars: polyhydroxyaldehydes or aldoses polyhydroxyketones or ketoses Disaccharides can be hydrolyzed to two monosaccharides. Polysaccharides hydrolyze to many monosaccharide units. For example, starch and cellulose have > 1000 glucose units. Chapter 23 Monosaccharides Classified using three criteria: If it contains a ketone or an aldehyde group. Number of carbons in the chain. Configuration of the asymmetric carbon farthest from the carbonyl group. Chapter 23 (+) and (-)-Glyceraldehydes The (+) enantiomer of . | Chapter 23 Copyright © 2010 Pearson Education, Inc. Organic Chemistry, 7th Edition L. G. Wade, Jr. Carbohydrates and Nucleic Acids Chapter 23 Carbohydrates Synthesized by plants using sunlight to convert CO2 and H2O to glucose and O2. Polymers include starch and cellulose. Starch is a storage unit for solar energy. Most sugars have formula Cn(H2O)n, “hydrate of carbon.” Chapter 23 Classification of Carbohydrates Monosaccharides or simple sugars: polyhydroxyaldehydes or aldoses polyhydroxyketones or ketoses Disaccharides can be hydrolyzed to two monosaccharides. Polysaccharides hydrolyze to many monosaccharide units. For example, starch and cellulose have > 1000 glucose units. Chapter 23 Monosaccharides Classified using three criteria: If it contains a ketone or an aldehyde group. Number of carbons in the chain. Configuration of the asymmetric carbon farthest from the carbonyl group. Chapter 23 (+) and (-)-Glyceraldehydes The (+) enantiomer of glyceraldehyde has its OH group on the right of the Fischer projection. The (-) enantiomer of glyceraldehyde has its OH group on the left of the Fischer projection. Chapter 23 Degradation of D and L Sugars Fischer–Rosanoff Convention D sugars can be degraded to the dextrorotatory (+) form of glyceraldehyde. L sugars can be degraded to the levorotatory (-) form of glyceraldehyde. Chapter 23 D and L Series of Sugars Sugars of the D series have the OH group of the bottom asymmetric carbon on the right in the Fischer projection. Sugars of the L series, in contrast, have the OH group of the bottom asymmetric carbon on the left. Chapter 23 The D Aldose Family Chapter 23 Erythrose and Threose Erythrose is an aldotetrose with the OH groups of its two asymmetric carbons on the same side of the Fischer projection. Threose is the diastereomer with the OH groups on opposite sides of the Fischer projection. D-(-)-erythrose D-(-)-threose Chapter 23 Erythro and Threo .