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Carbohydrate Classification

1. N u mbers 2. Location of carbonyl group 3. N u mber of carbon atoms 4. C o n figuration 5. Reactivity

Common hexoses 1. A ldoses 2. K etoses

Stereochemistry 1. C h i rality 2. Enantiomers 3. D- & L-sugars 4. P hysical properties 5. F isher projections 6. Haworth formulae 7. S t e reo projections 8. Chair presentations

Conformation 1. I n t ramolecular cyclization 2. A n o mer 3. M utarotation 4. F uranose & pyranose

Some important monosaccharide

1. D - g lyceraldehyde 2. D - g lucose 3. D - f ructose 4. D-galactose 5. D - ribose

Disaccharide 1. G lycosidic bond 2. Disaccharide

Oligosaccharide Polysaccharide

Carbohydrate

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¶ Sugar Glucose + Sucrose

· Starch

¸ Cellulose

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Carbohydrate Compounds contain C, H, O with

general formula of Cm(H2O)n

All have C=O and -OH functional groups

Classified based on Size of base carbon chain Number of sugar unit Location of C=O group Stereochemistry

Types of Carbohydrates Classification based on the number of sugar units in the total chain

Monosachcarides Single sugar unit Disaccharides Two sugar units Trisachcarides Three sugar units Oligosaccharides up to 10/13/ sugar units Polysaccharides > 13 sugar units

Chaining relies on the glycosidic bonds

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Fischer Projections

•  Used to represent carbohydrates (chiral carbons)

•  Places the most oxidized group at the top (C1)

•  Uses horizontal lines for bonds that come forward

•  Uses vertical lines for bonds that go back

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D and L Notations

•  By convention, the letter L is assigned to the structure with the —OH on the left

•  The letter D is assigned to the structure with —OH on the right

D and L Monosaccharides •  Stereochemistry determined by the asymmetric center

farthest from the carbonyl group

•  Most monosaccharides found in living organisms are D

D D L

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Aldose

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Ketone Sugars Ketones are not easy to oxidize except for ketoses

Enediol reaction -- All monosaccharides are reducing sugars

CHO

OHH

HHO

OHH

OHH

CH2OH

OH

HHO

OHH

OHH

CH2OH

OH

O

HHO

OHH

OHH

CH2OH

OH

Aldose Ketosecis-enediolintermediate

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Ketose

Pure Fruits Sweetly Taste

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Conformation Intramolecular cyclization

Anomer

Mutaroation

Furanose & pyranose

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Cyclization of D-glucose

β-D-glucose

α-D-glucose CHO

OHH

HHO

OHH

OHH

CH2OH

OHOHO

OHOH

OH

OHOHO OH

OH

OH

C

OH

OH

OH

OH

CH2OH

OH

OH

O

H

HO

HOOH

OH

a b

OH

H

HO

OHO

H

HOHO

OHO

OH

OH

H

OH

OH

a

b

Intramolecular Cyclization Chain can bend and rotate

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Fisher Projections

Haworth Formulae

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Stereo Projections

Chair Presentations

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OH

O

OH

OH

OH

OH

Aldose(Glucose)

OH

OH

OH

OH

OH

OH

OH

O

OH

OH

OH

OH

O

OH

O

OH

OH

OH

OH

OH

O

OH

O

OH

OH

OH

OH

OH

Alditol(Glucitol)

Aldouronic Acid(Glucuronic Acid)

Aldaric Acid(Glucaric Acid)

Aldonic Acid(Gluconic Acid)

[H][O] C-1 and C-6

[O] C-6[O] C-1

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Pyranose: Chair, Boat, Half-chair, Skew.

O

123

4 5

4C1

O4 5

3 2 1

4C1

O1

234

5

1C4

O

1

23

45

1,4B

Furanose: Envelope, Twist. O

1E

O

1T

O

O

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COMPLICATION OF CARBOHYDRATE

1.  Number of Carbon Atoms

2.  The Location of Carbonyl Group

3.  The Configuration of Sugar (D or L)

4.  The Size of Ring (5, 6 or 7)

5.  The Configuration at Position 1 (a or b)

6.  The Connectivity between Sugar Units

7.  Derivatives (oxidation, reduction, deoxy, various group)

CARBOHYDRATE ISOMERS Combination of Individual Units

Number of Carbohydrates

Two identical units, A-A dimer

11

Three identical units, A-A-A trimer

176

Three different units, A-B-C trimer

1,056

Five different units, A-B-C-D-E pentamer

2,144,640

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Starch Energy storage used by plant

Long repeating chain of a-D-glucose Chain up to 4000 units

Amylose Straight chain

Amylopectin Branched structure Major part of starch

Great for making gravy, jam & jelly

Starch can be found

Pasta, Rice , Potatos Bread

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Too much ….. Carbohydrate will be converted into fat and stored under the

skin leading to weight gain!