In this lecture, we will learn how to distinguish between ALDEHYDES and KETONES from other functional group through 2 4 DNP Test and Iodoform Test. This video was created in accordance with the latest syllabus for CBSE Class 12 Chemistry – Aldehydes & Ketones published by Brilliant Qatar.
2 4 DNP Test: Testing to identify aldehydes or ketones with 2,4- dinitrophenylhydrazine (DNPH) is a convenient way to separate mixture components between aldehydes and ketones. If an aldehyde or ketone is present a yellow, an orange or reddish-orange precipitate of the dinitrophenylhydrazine appears. When these compounds are brought to their melting point, this confirms the carbonyl compound.
iodoform test: When Iodine and sodium hydroxide are added to a compound that contains either a methyl ketone or a secondary alcohol with a methyl group in the alpha position, a pale yellow precipitate of iodoform or triiodomethane is formed. It can be used to identify aldehydes or ketones. If an aldehyde gives a positive iodoform test, then it must be acetaldehyde since it is the only aldehyde with a CH3C=O group