Question

What functional group gives a positive test in the xanthoproteic test?

Answer 1

Aromatic amino acids, due to the nitration of amino acids.

Step-by-step explanation:

Xanthoproteic test is a chemical test used to determine the amount of the protein in a solution. This is a type of qualitative test used for the determination of presence or absence of protein.

The xanthoproteic test is positive in case of aromatic amino acids only. The yellow color is formed in case of aromatic amino acids due to the formation of xanthoproteic acid. Phenylalanine, tyrsoine and tryptophan gives positive xanthoproteic test.

Answer 2

An aromatic group is a functional group which gives a positive test in a xanthoproteic test.
Xanthoproteic is a test for protein detention. The concentrated nitric acid reacts with proteins if they are present to form yellow colour. By adding alkali it turns orange-yellow through xanthoproteic reaction. Due to a phenyl group, the hydroxyl group can make the test positive in xanthoproteic.
An aromatic group consists of six hydrocarbons with an alternating single and double bond between carbon atoms which form rings.