OxidationBromino water .nitric acid

------------------------------- ----------------------------

C

C

C

C

C

CH2OH

OH

OH

H

OHH

HO

H

H

OH

C

C

C

C

COOH

OH

OH

H

OHH

HO

H

H

C

C

C

C

CH2OH

OH

OH

H

OHH

HO

H

H

COOHCOOH

Glucose Glucaric acidGluconic acid

Reduction

Carbonyl groups can be reduced to alcohols (catalytic hydrogenation)

Sweet but slowly absorbed

Glucose is reduced to sorbitol (glucitol)

Xylose can be reduced to xylitol

Once reduced – less reactive; not absorbed

R

H O[H]

H

R

H OH

Aldehyde sugars (reducing sugars) are readily oxidized

and will react with Benedict’s reagent.

This provides a good test for presence of glucose in urine -

forms a red precipitate.

Other tests - Tollen’s or Fehling’s solutions.

H |

C=O

| + 2 Cu 2+

+ 5 OH-

H-C-OH|

CH2OH

O-

|C=O

| + 2 Cu2O + 3H2OH-C-OH

|CH2OH

B enedict's

Reagent

0.5% 2%

glucos e

or -OH group of cyclic monosaccharide can form link

with another one (or more).

glycosidic bond

sugar -O- sugar

oxygen bridge

OH

OH

OH

H

H

H

OH

CH2OH

H

O H

OH

H

OH

H

OH H

OH

CH2OH

H

OH

OH

OH H

H

H

OH

CH2OH

H

O H

OH

H

H

OH H

OH

CH2OH

H

OH

o

+ H2 O

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.

H O

OH

OH

H

H

OHH

OH

CH2OH

H

-D-glucose -D-2-aminoglucose

(glucosamine)

H O

OH

OH

H

H

NH2H

OH

CH2OH

H

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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