Which reagent can be used to distinguish between butanone and butanal?

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Multiple Choice

Which reagent can be used to distinguish between butanone and butanal?

Explanation:
Aldehydes can act as reducing agents toward copper(II) in alkaline conditions, while most ketones cannot. When butanal (an aldehyde) is tested with alkaline Cu(OH)2, the aldehyde reduces Cu(II) to Cu(I), and a brick-red Cu2O precipitate forms, causing the blue precipitate of Cu(OH)2 to disappear or fade. Butanone (a ketone) does not readily reduce Cu(II) under these conditions, so the blue Cu(OH)2 remains, and there’s no brick-red precipitate. This difference in redox behavior provides a clear distinction between the two: butanal gives a positive Cu(OH)2 test, while butanone does not.

Aldehydes can act as reducing agents toward copper(II) in alkaline conditions, while most ketones cannot. When butanal (an aldehyde) is tested with alkaline Cu(OH)2, the aldehyde reduces Cu(II) to Cu(I), and a brick-red Cu2O precipitate forms, causing the blue precipitate of Cu(OH)2 to disappear or fade. Butanone (a ketone) does not readily reduce Cu(II) under these conditions, so the blue Cu(OH)2 remains, and there’s no brick-red precipitate. This difference in redox behavior provides a clear distinction between the two: butanal gives a positive Cu(OH)2 test, while butanone does not.

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