Barfoed's Test

Qualitative Analysis of Carbohydrates
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. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate. RCHO + 2Cu2+ + 2H2O → RCOOH + Cu2O↓ + 4H+ (Disaccharides may also react, but the reaction is much slower.)