Chapter 18: Carbohydrates Chem 330, Chapter 18 Carbohydrates Chapter 18: Carbohydrates glucose Copyright 2002, David R. Anderson

Monosaccharides Classification Stereoisomers Fischer projections D- and L-sugars Cyclic structures cyclic hemiacetals Haworth projections and chair conformations mutarotation Reactions glycosides (acetals) reduction oxidation Disaccharides and Oligosaccharides Polysaccharides

I. Monosaccharides A. Classification

I. Monosaccharides A. Classification

I. Monosaccharides B. Stereoisomers 1. Fischer projections

I. Monosaccharides B. Stereoisomers 2. D- and L-sugars

I. Monosaccharides B. Stereoisomers 2. D- and L-sugars

I. Monosaccharides B. Stereoisomers 2. D- and L-sugars aldopentoses: 3 chiral carbons, 8 stereoisomers (4 D & 4 L) aldohexoses: 4 chiral carbons, 16 stereoisomers (8 D & 8 L)

I. Monosaccharides B. Stereoisomers 2. D- and L-sugars

I. Monosaccharides C. Cyclic structures 1. cyclic hemiacetals

I. Monosaccharides C. Cyclic structures 1. Haworth projections and mutarotation

I. Monosaccharides C. Cyclic structures 1. Haworth projections and mutarotation

I. Monosaccharides C. Cyclic structures 2. chair conformations

Practice Exercises Draw the Haworth and chair structures of b-D-galactopyranose. What sugar is shown in the following structure? Name the structure.

I. Monosaccharides D. Reactions 1. glycosides (acetals)

I. Monosaccharides D. Reactions 2. reduction to alditols

I. Monosaccharides D. Reactions 2. oxidation to aldonic and aldaric acids

I. Monosaccharides D. Reactions 2. oxidation to aldonic and aldaric acids Reducing sugars: reduce Benedict’s solution (Cu+2  Cu2O)

II. Disaccharides

II. Disaccharides

Practice Exercises What two monosaccharides comprise lactose? What is its full name?

II. Disaccharides Reducing sugars: free hemiacetal (always in equilibrium with open chain aldehyde)

II. Polysaccharides