What is Barfoed's test?

Various tests are conducted to identify the class and group of compounds in organic chemistry. One among the test is Barfoed’s test. Let us know more about this.

Barfoed’s Test

The Barfoed’s test is used to differentiate reducing monosaccharide from a disaccharide sugar. The reaction is conducted in a slightly acidic medium.

How to conduct the Barfoed’s test?

A mixture of ethanoic (acetic) acid and copper(II) acetate, is added to the test solution and boiled.

Reaction

RCHO + 2 Cu2+ + 2 H2O —–> RCOOH + Cu2O + 4H

Reducing monosaccharides react with Bedford’s reagent much faster than disaccharides and produce a copious amount of red precipitate of copper (I) oxide within three minutes. Disaccharide sugars as they are weaker reducing agents, react at a slower rate and so do not form red precipitate even for ten minutes. Some hydrolysis of disaccharides may lead to trace precipitates which tends to adhere to the walls of the test tube.

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