How do we know if a compound gives Schiff’s reagent test or not?

							Schiff,s test is an general chemical test for detection of aldehydes.This reaction was developed by Hugo Schiff.The Schiff reagent is the reaction product of a dye formulation like fuchsin and sodium bisulfite; pararosaniline and new fuchsin.The unknown sample is added to the decolorized Schiff reagent,when aldehyde is present a characteristic magenta color develops which is use as a qualitative test for aldehydes.In the reaction Schiff reagent acts as a nucleophile that adds to the carbonyl group of an aldehyde.Because this nucleophile is extremely bulky,a ketone, which is more sterically crowded than an aldehyde at the carbonyl carbon,does not react with Schiff's reagent,and thus does not produce the magenta color. Production of the magenta color therefore indicates that the unknown sample is an aldehyde and not a ketone.Thus aldehydes with carbonyl group gives this test,but if an organic compound gives test for carbonyl group but fails to give Schiff ’s test then it is a ketone.