Oxidation
Bromino water
-------------------------------
O
H
.nitric acid
----------------------------
C
COOH
COOH
H
C
OH
HO
C
H
H
H
C
OH
C
OH
CH
OH
2
Gluconic acid
H
C
OH
HO
C
H
H
C
OH
C
OH
CH
OH
2
H
Glucose
H
C
OH
HO
C
H
H
C
OH
C
OH
H
COOH
Glucaric acid
Reduction

Carbonyl groups can be reduced to alcohols (catalytic
hydrogenation)
H
O
R




H
[H]
H
OH
R
Sweet but slowly absorbed
Glucose is reduced to sorbitol (glucitol)
Xylose can be reduced to xylitol
Once reduced – less reactive; not absorbed

Aldehyde sugars (reducing sugars) are readily oxidized
and will react with Benedict’s reagent.
H
|
C=O
|
+ 2 Cu
H-C-OH
|
CH2OH
-
2+ + 5 OH-
O
|
C=O
|
+ 2 Cu2O + 3H2O
H-C-OH
|
CH2OH

This provides a good test for presence of glucose in urine forms a red precipitate.

Other tests - Tollen’s or Fehling’s solutions.
glucos e
0.5%
B enedict's
Reagent
2%

 or  -OH group of cyclic monosaccharide can form link
with another one (or more).
CH2OH

glycosidic bond
CH2OH
O
H
H
OH
OH
H
H
H
sugar -O- sugar
O
H
OH

H
H
H
OH
OH
OH
OH
OH
H
CH2OH

oxygen bridge
CH2OH
H
O
H
H
OH
o
H
H
OH
H
H
H
OH
OH
H
OH
O
OH
+ H2 O
H
Type is based on the position of the C-1 OH
 glycosidic bond
- linkage between a C-1  OH and a C-4 OH
 glycosidic bond
- linkage between a C-1  OH and a C-4 OH
 bonds
 bonds
O
O
O
O
C-4 end can be either up or down depending
on the orientation of the monosaccharide.

The replacement of a hydroxyl group on a carbohydrate
results in an amino sugar.
CH2OH
CH2OH
O
H
H
OH
OH
H
OH
H
H
OH
H
OH
-D-glucose
O
H
OH
H
H
OH
H
NH2
-D-2-aminoglucose
(glucosamine)

Uses for amino sugars.

Structural components of bacterial cell walls.

A major structural unit of chondroitin sulfate - a
component of cartilage.

Component of glycoprotein and glycolipids.
Osazone formation
Dehydration
Glucose + H2SO4 ------------- hydroxyl methyl furfural +3H2O
Xylose + Hcl -------- furfural + 3H2O
Furfural
+  naphthol ------ violette ring
hydroxyl methyl furfural +  naphthol ------ violette ring
Furfural + orcinol -------- green ppt (Bial test)
hydroxyl methyl furfural + Resorcinol -------- red ppt
(salwanoffe test)
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