Verification of fructose as hydroxymethylfurfural

Chemicals

fructose

resorcin Xn   N    R 22-36/38-50     S (2)-26-61

hydrochloric acid 30-33%  C    R 34-37     S (1/2)-26-45

Instead of resorcin one can also use 1-naphthol (see literature).

Equipment needed

test tube
burner (preferably alcohol)

Test procedure

• Safety goggles!
• Add a spatula-tipful resorcin and a spatula-tipful fructose to the test tube.
• Then add approx. 0.3 ml concentrated hydrochloric acid and gently warm with the burner.
• A red color appears.

Disposal

The diluted residue can be discharged into the drainage.

Elucidation

Due to the seperation of water fructose 5 -(hydroxymethyl)furfural is formed. This reacts with resorcin along with a renewed seperation of water to form the colorant shown below, as well as isomers of this. The formation of furfural derivates, upon which this verification is based, succeeds under these conditions only with certain ketoses.

Photos

Verification of fructose

Literature

Derived from p. 203, [4]

Concerning the use of 1-naphthol as a detection agent: to be added, [3]