CBSE Class 12 · 2008 · Delhi · Aldehydes Ketones and Carboxylic AcidsShort Answer

Give chemical tests to distinguish between:
i) acetaldehyde and benzaldehyde
ii) propanone and propanol

Solution

(i) Fehling's solution: acetaldehyde (aliphatic) → red Cu

_{2}

O precipitate; benzaldehyde (aromatic) does not reduce Fehling.
(ii) 2,4-Dinitrophenylhydrazine: propanone (a carbonyl) gives an orange precipitate; propanol does not. (Conversely sodium metal effervesces H

_{2}

with the alcohol only.)

CBSE Class 12 Board · 2008 · Delhi · Subjective

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