JEE Advanced · 2012 · 08 Apr 2012 · Paper 1 · Practical and Analytical Chemistry

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Identify the binary mixture(s) that can be separated into individual compounds, by differential extraction, as shown in the given scheme.

(A) $C_{6} H_{5} OH$ and $C_{6} H_{5} COOH$
(B) $C_{6} H_{5} COOH$ and $C_{6} H_{5} CH_{2} OH$ ✓ Correct
(C) $C_{6} H_{5} CH_{2} OH$ and $C_{6} H_{5} OH$
(D) $C_{6} H_{5} CH_{2} OH$ and $C_{6} H_{5} CH_{2} COOH$ ✓ Correct

Answer: (B), (D)

Solution

The differential extraction scheme uses NaOH and

NaHCO_{3}

sequentially. Carboxylic acids (

C_{6} H_{5} COOH

C_{6} H_{5} CH_{2} COOH

) are soluble in both NaOH and

NaHCO_{3}

. Phenol (

C_{6} H_{5} OH

) is soluble in NaOH but not in

NaHCO_{3}

. Benzyl alcohol (

C_{6} H_{5} CH_{2} OH

) is not soluble in either.

(A) Both phenol and benzoic acid dissolve in NaOH — inseparable by this scheme.
(B) Benzoic acid dissolves in both bases; benzyl alcohol in neither — separable.
(C) Phenol dissolves in NaOH; benzyl alcohol in neither. However, both are insoluble in

NaHCO_{3}

, making complete separation difficult by this two-step scheme.
(D) Phenylacetic acid dissolves in both bases; benzyl alcohol in neither — separable.

Options (B) and (D) can be separated.

JEE Advanced · 2012 · 08 Apr 2012 · Paper 1 · One or more correct options

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JEE Advanced · 2012 · 08 Apr 2012 · Paper 1 · Practical and Analytical Chemistry

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