Carbohydrates

1  Carbohydrates

Outline - Chapter 7 in Text

2  Definitions

3  Stereochemistry Definitions

4  Fischer Projections

Horizontal lines: Projections above plane

Vertical lines: Groups lies below plane


fischer.gif
glyceraldehyde.jpg


5  Aldose vs. Ketose


glucose.gif
      fructose.gif



AldoseKetose
Contains aldehydeContains Ketone

6  Isomers

# isomers = 2 n      where n = # chiral centers

See Figure 7.4 (textbook p. 154)

D-glyceraldhyde

D-erythrose & D-threose

D-ribose & D-arabinose & D-xylose & D-lyxose

D-allose & D-altrose & D-glucose & D-mannose  &
D-gulose & D-idose & D-galactose & D-talose

7  Hemiacetals

coadd.gif


Addition of alcohol to aldehyde gives hemiacetal


RCHO  +  R'OH       R-CH(OH)-OR'


In carbohydrates, reaction is intramolecular (within one molecule) and gives a cyclic structure.

8  Cyclic Structures

Equilibrium concentrations of D-glucose in solution

9  Formation of Cyclic Pyranose

CyclicA6.gif


Pyranose: 6-membered ring

10  D-Glucopyranose (3-D)

glu.gif


11  Anomeric Carbon

glucopyranoseA.png
glucopyranoseB.png


a-form: -OH group 'down'

b-form: -OH group 'up'

12  Formation of Cyclic Furanose

CyclicF5.gif


Furanose: 5-membered ring

13  Reactions

14  Monosaccharides: Glucose

glucose.gif
     glucopyranoseA.png


15  Monosaccharides: Fructose

fructose.gif
     fructofuranoseB.png


16  Disaccharides

monosaccharide  +  monosaccharide       disaccharide



Glycosidic linkage:


sugar 1 -OH  +  HO-sugar 2     \rightleftharpoons    sugar 1 -O-sugar 2
  +  H 2 O

17  Lactose

lactoseA.png


b-D-galactose  +   a-D-glucose    \rightleftharpoons    lactose


18  Sucrose

sucrose.png


a-D-glucose  +   b-D-fructose    \rightleftharpoons    sucrose


19  Polysaccharides

20  Other Polysaccharides




File translated from TEX by TTH, version 3.02.
On 25 Feb 2002, 17:06.