2,4-dinitrophénylhydrazine

The 2,4-dinitrophénylhydrazine (or 2,4-DNPH ) is used as test characteristic of the Aldéhyde S and of the Cétone S. It is synthesized by aromatic nucleophilic subsitution of hydrazine on the 1-chloro (or 1-bromo) 2,4-dinitrobenzene.

The preparation of a solution of reagent can be obtained as follows: one gently dilutes 3 G of DNPH in 15 ml of H2SO4 with 98%,20 ml of Water and 70 ml of ethanol. It is necessary to envisage to cool to avoid any heating.

Test

One mixes the Composé organics to be tested with 2,4-DNPH. If a yellow-orange Précipité of 2,4-dinitrophénylhydrazone appears, the test is positive and the Composé organics is either a Aldéhyde, or a Cétone. If not, the test is negative, and the Composé organics is neither a Aldéhyde, nor a Cétone.

See too

  • the Fehling's solution for a test specific to aldehydes.

  • the solution of Tollens for a test specific to aldehydes.
  • the Reaction of Schiff for a test specific to aldehydes.

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