Question

(X) $\xrightarrow[\text{FeBr}_3]{\text{Br}_2}$ (i) $\text{NaOH}$, 623 K, 300 atm; (ii) dil. HCl $\xrightarrow{\text{HNO}_3}$ A + B. The organic product (A) and (B) can be separated by :

• A. Steam distillation
• B. Fractional distillation
• C. Distillation under reduced pressure
• D. Azeotropic distillation

Hint:

Differences in volatility due to H-bonding type (Intra vs Inter) allow separation of ortho and para isomers of nitrophenols and hydroxybenzaldehydes via steam distillation.

Answer 1

The Correct Option is A

Let's analyze the given chemical reaction step by step to understand how the reaction proceeds and how the products can be separated.

1. Initial Reaction: The given reaction is \((X) \xrightarrow[\text{FeBr}_3]{\text{Br}_2}\), which indicates an aromatic bromination. This is an electrophilic substitution reaction where benzene or its derivative (X) reacts with bromine using FeBr₃ as a catalyst, typically resulting in the formation of a brominated aromatic compound.
2. Subsequent Reaction with NaOH: The brominated compound undergoes hydrolysis at high temperature (623 K) and pressure (300 atm) with NaOH, followed by acidification with dilute HCl. This reaction conditions are indicative of a nucleophilic aromatic substitution, likely resulting in phenol derivatives.
3. Nitration Reaction: Next, the reaction with HNO₃ suggests nitration, leading to the formation of nitrophenol compounds – specifically, ortho-nitrophenol (A) and para-nitrophenol (B).
4. Separation by Steam Distillation: The key to resolving which method separates A and B lies in their physical properties. Ortho-nitrophenol can form intramolecular hydrogen bonding, resulting in a lower boiling point than para-nitrophenol, which exhibits stronger intermolecular hydrogen bonding and thus a higher boiling point. This difference in boiling points makes steam distillation an ideal method to separate them, as it is a technique suitable for separating compounds with different volatility.

Thus, the organic compounds (A) and (B), ortho-nitrophenol and para-nitrophenol, can be effectively separated using steam distillation due to the difference in their boiling points and volatility. Therefore, the correct answer is: Steam distillation.