Schiff's reagent test is a qualitative test to detect aldehydes, giving a pink/magenta color due to the formation of a complex.
Schiff's reagent
Step 1: Schiff’s reagent is used to distinguish between aldehydes and ketones. Aldehydes react with Schiff’s reagent to give a pink color, whereas ketones do not react. Since acetaldehyde is an aldehyde and acetone is a ketone, Schiff’s reagent can differentiate between them
Ethanal to But-2-enal