Chemistry - GOC Question with Solution | TestHub
A mixture of 4-methylbenzoic acid, 4-methylcyclohexanol and p-xylene is dissolved in ether and shaken with aqueous NaHCO₃; the layers are separated. The ether layer is then shaken with aqueous NaOH and separated again. The first aqueous layer is acidified with HCl and extracted with ether.
Identify the contents : Flask 1 (aqueous layer from NaOH), Flask 2 (ether layer after NaOH), Flask 3 (ether extract after HCl), Flask 4 (final aqueous layer).
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Answer:
Solution:
Only the carboxylic acid is strong enough to react with NaHCO₃, so it alone enters the first aqueous layer as sodium 4-methylbenzoate; the alcohol and the hydrocarbon stay in the ether. Neither 4-methylcyclohexanol nor p-xylene reacts with NaOH, so the NaOH wash takes nothing organic into Flask 1 and both compounds remain in ether (Flask 2). Acidifying the first aqueous layer with HCl reprotonates the carboxylate, and 4-methylbenzoic acid moves into the ether extract (Flask 3), leaving NaCl in the final aqueous layer (Flask 4).
