Which of the following amino acid will give violet coloured complex with neutral ferric chloride solution?
Solution
Solution
Neutral FeCl gives a violet colour with phenols. Of the four, only tyrosine has a phenolic –OH (a 4-hydroxyphenyl side chain). Threonine and serine have alcoholic –OH groups and cysteine has –SH; none of these gives the test.
Answer: Tyrosine.
Answer checked against the official answer key. The solution is our own working.