Benedict's test is a test to determine whether an organic compound contains an alkyl aldehyde group, but not an aromatic aldehyde group. Benedict modified the original费林的测试and made a reagent that is a single solution, which is more convenient. Benedict’s reagent is more stable than Fehling’s reagent so it can be stored for a long time. Benedict's reagent is an alkaline solution containing a mixture of copper sulfate and sodium citrate (2Na₃C₆H₅O₇•11H₂O). When the reagent encounters an aldehyde, the Cu²⁺ions are reduced to Cu⁺ions. Benedict's reagent is also used to detectreducing sugars, typically monosaccharides or disaccharides, e.g. glucose.

材料

• Test tubes

• Test tube rack

• Benedict's reagent

• Compound to be tested

Safety

Benedict's reagent is harmful and an environmental hazard.

过程

1. Add 5 drops of the liquid compound or the solution of the solid organic compound in water or alcohol to a test tube.

2. Add 2 mL of Benedict’s reagent.

3. Place the test tube into a water bath of boiling water for 5 minutes.

4. An orange-red precipitate indicates the presence of an aldehyde. This test does not show if an aromatic aldehyde is present.

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References:

• NCERT Lab Manual for Functional Group tests