BRAINCAKEQualitative Tests for Carbonyls
Aldehydes and ketones both contain the carbonyl group, C=O. Two tests are used together.
1. 2,4-Dinitrophenylhydrazine (2,4-DNP), also called Brady's reagent, detects any carbonyl group. Add a few drops of the sample to 2,4-DNP solution:
• aldehydes and ketones give a yellow or orange precipitate (a 2,4-dinitrophenylhydrazone derivative)
• other compounds containing C=O, such as carboxylic acids and esters, do not
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All 10 lessons in Chromatography and Qualitative Analysis · All OCR A-level Organic Chemistry topics