Lesson 4.3. General Test for Polysaccharides

1 g of starch

Preparation of the 1% Starch Solution:

1. Weight __________________

2. Add _____________________

3. Ratio it to __________

1 = ?

100 mL of distilled water

Preparation of the 1% Starch Solution:

1. Weight __________________

2. Add _____________________

3. Ratio it to __________

2 = ?

20 mL

Preparation of the 1% Starch Solution:

1. Weight __________________

2. Add _____________________

3. Ratio it to __________

3 = ?

a-naphthol in 95% EtOH

Procedure for Molisch’s Test:

1. To 0.5 ml of the 1% starch solution (sample) add a few drops of Molisch’s reagent (__________________)

2. Incline the test tube and carefully add _____________ down the side of the tube.

1 = ?

conc. H2SO4

Procedure for Molisch’s Test:

1. To 0.5 ml of the 1% starch solution (sample) add a few drops of Molisch’s reagent (__________________)

2. Incline the test tube and carefully add _____________ down the side of the tube.

2 = ?

H2SO4, Ethanol, and a-napthol

reagents of Molisch’s test

monosaccharides to produce furfural or hydroxymethylfurfural

Principle involved in Molisch’s Test:

1. Strong acid such as H2SO4 dehydrates ____________________________.

2. _______________________________________ will condense with a-naphthol

a. ________________________ will have a faster reaction

b. _______________________________ will have a slower reaction

1 = ?

Intermediate furfural derivatives

Principle involved in Molisch’s Test:

1. Strong acid such as H2SO4 dehydrates ____________________________.

2. _______________________________________ will condense with a-naphthol

a. ________________________ will have a faster reaction

b. _______________________________ will have a slower reaction

2 = ?

monosaccharides

Principle involved in Molisch’s Test:

1. Strong acid such as H2SO4 dehydrates ____________________________.

2. _______________________________________ will condense with a-naphthol

a. ________________________ will have a faster reaction

b. _______________________________ will have a slower reaction

2.a. = ?

oligosaccharides and polysaccharides

Principle involved in Molisch’s Test:

1. Strong acid such as H2SO4 dehydrates ____________________________.

2. _______________________________________ will condense with a-naphthol

a. ________________________ will have a faster reaction

b. _______________________________ will have a slower reaction

2.b. = ?

purple ring at interface

positive color for Molisch’s Test

all carbohydrates

Molisch’s Test will positive for:

0.01M or 0.2% Iodine solution

Iodine Test Procedure:

1. To 0.5 ml of the starch solution (sample) add few drops of _______________. Observe color change.

2. Warm the mixture in a ______________

1 = ?

water bath

Iodine Test Procedure:

1. To 0.5 ml of the starch solution (sample) add few drops of _______________. Observe color change.

2. Warm the mixture in a ______________

2 = ?

monosaccharide and disaccharide from polysaccharide

Iodine Test differentiates:

monosaccharides and disaccharides

Iodine Test does not react with:

complexation

principle of Iodine Solution

blue-black solution

In Iodine test, starch is present if the color is a _____________ due to the presence of starch-iodo complex

red or pink solution

In Iodine test, glycogen is present if the color is a _________________ due to the presence of glycogen-iodo complex

Epimerization

process of changes of configuration of ONLY ONE chiral center