Question

An organic compound with molecular formula C₇H₈O dissolves in NaOH and gives a characteristic colour with FeCl₃. On treatment with bromine, it gives a tribromo derivative C₇H₅OBr₃. The compound is

• A. m - Cresol
• B. Benzyl alcohol
• C. p - Cresol
• D. o - Cresol

Answer 1

The Correct Option is A

Cresols are aromatic compounds with the general formula \(\text{C}_6\text{H}_4(\text{CH}_3)(\text{OH})\)
They are derivatives of phenol, where the methyl group \((CH_3)\) is substituted on the benzene ring.
 Cresols have three isomers: 

• o-cresol (ortho-cresol), 
• m-cresol (meta-cresol), and 
• p-cresol (para-cresol).

When m-cresol \((\text{C}_7\text{H}_8\text{O})\) is treated with bromine \((Br_2)\), it undergoes electrophilic aromatic substitution and forms a tribromo derivative, \(\text{C}_7\text{H}_5\text{OBr}_3\)
 In this case, the compound is brominated at the meta position on the benzene ring, resulting in tribromination.
The given molecular formula \(\text{C}_7\text{H}_8\text{O}\) corresponds to the molecular formula of m-cresol. Furthermore, m-cresol is known to dissolve in NaOH and gives a characteristic color with \(FeCl_3.\)
Therefore, the organic compound in question is m-cresol (option A).

Answer 2

Correct answer: m - Cresol

Explanation:

• The compound has molecular formula C₇H₈O, which matches with cresol (methylphenol).
• It dissolves in NaOH and gives a violet color with FeCl₃, indicating the presence of a phenol group (–OH attached to benzene ring).
• On bromination, it forms a tribromo derivative (C₇H₅OBr₃), which is characteristic of phenols with activating groups in ortho and para positions.
• In m-cresol, the –CH₃ group is para to the –OH group, allowing bromine to substitute all three available ortho and para positions easily to give the tribromo derivative.

Hence, the compound is m-Cresol.