NEET 2018 · ChemistryIodoform testPrevious Year Question

Compound $A$ , $C X_{8} H X_{10} O$ , reacts with NaOI (produced by reacting $Y$ with NaOH) and yields a yellow precipitate with characteristic smell. $A$ and $Y$ are respectively:

Answer: (A) (A) $C X_{6} H X_{5} CH (OH) CH X_{3}$ and $I X_{2}$ . \textbf{Answer:} (A) $C X_{6} H X_{5} CH (OH) CH X_{3}$ (1-phenylethanol) and $I X_{2}$ \textbf{Solution:} NaOI is generated in situ from $I X_{2} + 2 NaOH NaOI + NaI + H X_{2} O$ , so $Y$ = $I X_{2}$ .

A.(A) $C X_{6} H X_{5} CH (OH) CH X_{3}$ and $I X_{2}$ ✓
B.(B) $C X_{6} H X_{5} CH X_{2} CH X_{2} OH$ and $I X_{2}$
C.(C) $H X_{3} C - C X_{6} H X_{4} - CH X_{2} OH$ and $I X_{2}$
D.(D) $(CH X_{3}) X_{2} C X_{6} H X_{3} OH$ and $I X_{2}$

Correct Answer

(A) (A) $C X_{6} H X_{5} CH (OH) CH X_{3}$ and $I X_{2}$

Solution & Explanation

\textbf{Answer:} (A) $C X_{6} H X_{5} CH (OH) CH X_{3}$ (1-phenylethanol) and $I X_{2}$ \textbf{Solution:} NaOI is generated in situ from $I X_{2} + 2 NaOH NaOI + NaI + H X_{2} O$ , so $Y$ = $I X_{2}$ . A yellow precipitate with characteristic smell is iodoform, $CHI X_{3}$ , i.e. a positive iodoform test. 1-Phenylethanol $C X_{6} H X_{5} CH (OH) CH X_{3}$ (a secondary alcohol, $C X_{8} H X_{10} O$ ) is oxidised by NaOI to acetophenone $C X_{6} H X_{5} COCH X_{3}$ ; the $CH X_{3} CO X^{-}$ group then undergoes the haloform reaction to give $CHI X_{3}$ and sodium benzoate $C X_{6} H X_{5} COONa$ .

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Compound A, CX8​HX10​O, reacts with NaOI (produced by reacting Y with NaOH) and yields a yellow precipitate with characteristic smell. A and Y are respectively:

Solution & Explanation

More NEET PYQ solutions

Compound $A$ , $C X_{8} H X_{10} O$ , reacts with NaOI (produced by reacting $Y$ with NaOH) and yields a yellow precipitate with characteristic smell. $A$ and $Y$ are respectively: