Question

An organic compound having the molecular formula $C_7H_8O$ is insoluble in $NaHCO_3$ solution but dissolves in aqueous NaOH. When treated with bromine water the compound rapidly forms a precipitate having molecular formula $C_7H_5OBr_3$. Then the organic compound is

• A. O-Cresol
• B. m-cresol
• C. p-cresol
• D. anisole

Answer 1

Answer: (B)

m-cresol

Answer 2

The compound's molecular formula is $C_7H_8O$. Its solubility in NaOH but insolubility in $NaHCO_3$ indicates it is a phenol. Among the cresols (o-, m-, p-cresol) that fit the molecular formula, only m-cresol has three available ortho/para positions (C2, C4, C6) relative to the activating -OH group for electrophilic substitution. This allows for the formation of a tribromo derivative ($C_7H_5OBr_3$) upon reaction with bromine water, which matches the given product.