Carbohydrate Technology Dudsadee Uttapap

References: Key words: -Carbohydrate structure -Monosaccharide -Lecture

What is carbohydrate? Carbon + H2O Polyhydroxy aldehydes, ketones and their derivatives, and the polymer derived from these compounds

Aldose & Ketose

Carbon Formula/name aldose ketose 3 4 5 6 7 C3H6O3 C4H8O4 C5H10O5 Glyceraldehydes Erythrose Ribose xylose Glucose Galactose - Dihydroxyacetone Erythrulose Ribulose Xylulose Fructose Tagatose Sedoheptulose can be up to nine

Aldose

Ketose

D,L-isomers (stereochemical designation

isomer = 2n n = No. of chiral center

The D enantiomers of sugars predominate in nature

Enantiomers and Epimers

Structural Representation Acyclic system Fisher projections Wedge-Slash formula

Cyclic system Fischer VS Haworth Projection

Cyclization “Intramolecular hemiacetals/hemiketals” Aldose containing at least 5 C or ketose containing at least 6 C

Cyclization of glucose

Cyclization of ribose

Glucose Fructose

Cyclic sugar

Alpha-/beta-ANOMERS New chiral center 2 stereoisomer (anomers)

Chair conformations are generally more stable than boat conformations Glucose conformation Chair conformations are generally more stable than boat conformations

Reducing/Nonreducing sugar A reducing sugar has to have a free anomeric carbon

Reducing power

Properties of Mutarotation Reducing sugar ในสภาพสารละลายทุกตัวเป็น Optically active (rotate the plane of polarized light) เมื่อละลาย Reducing Sugar จะเห็นการเปลี่ยนแปลง Rotation กับ เวลา เรียก “Mutarotation” ตัวอย่าง น้ำตาล fructose ละลายน้ำ เริ่มต้น Specific Rotation ()D20 = -133 ที่จุดสมดุลย์ = -92.3 น้ำตาล glucose ละลายน้ำ เริ่มต้น Specific Rotation ()D20 = +112.2 ที่จุดสมดุลย์ = -52

Open-chain < 1%

Glucose Derivatives

Amino sugar

Sugar acid

Sugar Phosphate

Sugar Alcohol

Glycosidic/acetal linkage Glycoside Glycosidic/acetal linkage

Carbohydrate Nomenclature (alpha)- and  (beta)-D-Glucopyranose [1,2] (alpha)- and  (beta)-D-Glucofuranose [3,4]

1,2,3,4,6-Penta-O-acetyl- (alpha) -D-Glucopyranose [5] 4-O-acetyl-1,2-di-O-benzoyl-6-O-p-tolylsulfonyl- (alpha) -D-galactopyranose [6]

1,6-Anhydro- (beta)-D-Glucopyranose [14] 4,6-O-Benzylidene- (beta) -D-Glucopyranose [7] 1,2:5,6-Di-O-isopropylidene- (alpha) -D-Glucopyranose [8] 1,6-Anhydro- (beta)-D-Glucopyranose [14]

Glycosides Methyl- (alpha) -D- mannopyranoside [9] O-(6-O-Methyl- (alpha) -D-Galactopyranosyl)-(1 4)-  (alpha) -D-Galactopyranose [19]

Methyl-6-Deoxy- (alpha) -D- mannopyranoside [10] 6-Amino-6-deoxy- (alpha) -D- glucopyranose [11] 6-Deoxy-6-iodo- (beta) -D- galactopyranose [12]