Which of the following compounds comprise of a phenolic group?
(A) Salicylic acid
(B) Salicylaldehyde
(C) Cresol
(D) Catechol
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → (A), (B), (C) and (D)
A phenolic group is an –OH group attached directly to a carbon atom of a benzene ring. Other groups on the same ring (–COOH, –CHO, –\( \ce{CH3} \) or a second –OH) do not change this.
(A) Salicylic acid — Correct. It is 2-hydroxybenzoic acid, \( o\text{-}\ce{HOC6H4COOH} \): the –OH is on the ring.
(B) Salicylaldehyde — Correct. It is 2-hydroxybenzaldehyde, \( o\text{-}\ce{HOC6H4CHO} \), made from phenol by the Reimer-Tiemann reaction.
(C) Cresol — Correct. Cresols are methylphenols, \( \ce{CH3C6H4OH} \) (o-, m- and p-cresol).
(D) Catechol — Correct. Catechol is benzene-1,2-diol, \( o\text{-}\ce{C6H4(OH)2} \), with two phenolic –OH groups.