Question

Schiff's reagent gives pink colour with:
A. acetaldehyde
B. acetone
C. acetic acid
D. methyl acetone

Answer 1

Hint: The Schiff test is an early organic chemistry named reaction developed by Hugo Schiff and it is used in the staining of biological tissues such as Feulgen stain (detect chromosomal material) and periodic Schiff stain (detect polysaccharides such as glycogen).

Complete step by step answer:
As the name suggests, Schiff test is the chemical test for the detection of many aldehydes. As we know aldehydes are organic compounds that incorporate a carbonyl functional group C=O and the carbon atom of this group has two remaining bonds that may be occupied by hydrogen or alkyl.

Now let us discuss the Schiff test in brief: this test used as a qualitative test for aldehydes where an unknown sample is added to the decolorized Schiff reagent and thus in the presence of aldehyde a characteristic magenta color develops.
Therefore, it is concluded that the Schiff test gives pink color when reacting with aldehyde.

Hence, the correct option is (A).

This test is used to differentiate aldehyde and ketone and gives the positive test for aldehyde.
Now let us discuss why other options are incorrect: From the above options except aldehyde all groups contain carboxyl groups. Therefore, Schiff reagent does not react with the carboxyl group and hence does not give pink color.

Note: Do not confuse the carbonyl group with the carboxyl group because the carboxyl group has both the carbonyl group and hydroxyl group while the carbonyl group is a functional group composed of a carbon atom double-bonded to an oxygen atom.