Question

Write the structures of A, B, and C in the following reactions:

Hint:

- Ethyl cyanide and ethyl amide are intermediates in this nucleophilic substitution and hydrolysis sequence. - In diazotization reactions, the diazonium ion is formed by reacting amines with nitrous acid.

Answer 1

(a) \[ \text{A} = \text{CH}_3\text{CH}_2\text{CN} \quad \text{(Ethyl Cyanide)} \] \[ \text{B} = \text{CH}_3\text{CH}_2\text{CONH}_2 \quad \text{(Ethyl Amide)} \] \[ \text{C} = \text{CH}_3\text{CH}_2\text{NH}_2 \quad \text{(Ethyl Amine)} \] - Step 1: Ethyl bromide (CH\(_3\)CH\(_2\)Br) reacts with KCN via nucleophilic substitution to yield ethyl cyanide (A). - Step 2: Partial hydrolysis of ethyl cyanide (A) in the presence of OH\(^-\) converts the nitrile group to an amide, forming ethyl amide (B). - Step 3: Ethyl amide (B) reacts with NaOH + Br\(_2\) to produce ethyl amine (C) through halogenation and basic hydrolysis.


(b) - Step 1: Nitrobenzene is reduced by Fe + HCl to form aniline (A).

- Step 2: Aniline (A) reacts with NaNO\(_2\) + HCl at 273-278 K to form a diazonium salt (B).

- Step 3: The diazonium salt (B) couples with phenol (C) in the presence of NaOH to yield phenol (C).