Question

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

• A. $C_6H_5OH$ and $C_6H_5COOH$
• B. $C_6H_5COOH$ and $C_6H_5CH_2OH$
• C. $C_6H_5CH_2OH$ and $C_6H_5OH$
• D. $C_6H_5CH_2OH$ and $C_6H_5CH_2COOH$

Answer 1

Answer: (D)

$C_6H_5CH_2OH$ and $C_6H_5CH_2COOH$

Answer 2

For separation by differential extraction one of the component must form salt with the given base so that the salt will be extracted in aqueous layer leaving other component in organic layer.
(a) Both phenol and benzoic acid forms salt with NaOH, hence this mixture can-t be separated.
(b) Benzoic acid forms salt with NaOH while benzyl alcohol does not, hence the mixture can be separated using NaOH.
Also benzoic acid forms salt with $NaHCO_3$ but benzyl alcohol does not, hence $NaHCO_3$ can be used for separation.
(c) Neither benzyl alcohol nor phenol forms salt with $NaHCO_3$, mixture cannot be separated using $NaHCO_3$.
(d) $C_6H_5CH_2COOH$ forms salt with $NaOH_3 C_6H_5CH_2OH$ does not, hence mixture can be separated using $NaOH_3$