Assertion (A) Only a small amount of HCl is required in the reduction of nitro compounds with iron scrap and HCl in the presence of steam.
Reason (R) $\mathrm{FeCl}_2$ formed gets hydrolysed to release HCl during the reaction.
Assertion (A) Aromatic $1^{\circ}$ amines can be prepared by Gabriel phthalimide synthesis.
Reason (R) Aryl halides undergo nucleophilic substitution with anion formed by phthalimide.
Assertion (A) Acetanilide is less basic aniline.
Reason (R) Acetylation of aniline results in decrease of electron density on nitrogen.
A hydrocarbon ' A ' $\left(\mathrm{C}_4 \mathrm{H}_8\right)$ on reaction with HCl gives a compound ' B ', $\left(\mathrm{C}_4 \mathrm{H}_9 \mathrm{Cl}\right)$, which on reaction with 1 mol of $\mathrm{NH}_3$ gives compound ' C ', $\left(\mathrm{C}_4 \mathrm{H}_{11} \mathrm{~N}\right)$. On reacting with $\mathrm{NaNO}_2$ and HCl followed by treatment with water, compound 'C' yields an optically active alcohol, 'D'. Ozonolysis of 'A' gives 2 mols of acetaldehyde. Identify compounds 'A' to 'D'. Explain the reactions involved.
(i) Addition of HCl to compound ' $A$ ' shows that compound ' $A$ ' is alkene. Compound ' $B$ ' is $\mathrm{C}_4 \mathrm{H}_9 \mathrm{Cl}$.
(ii) Compound ' $B$ ' reacts with $\mathrm{NH}_2$, it forms amine ' C '.
$$\mathrm{\mathop {{C_4}{H_8}}\limits_{[A]} \buildrel {HCl} \over \longrightarrow \mathop {{C_4}{H_9}Cl}\limits_{[B]} \buildrel {N{H_3}} \over \longrightarrow \mathop {{C_4}{H_{11}}N}\limits_{[C]} \,or\,{C_4}{H_3}N{H_2}}$$
(iii) ' C ' gives diazonium salt with $\mathrm{NaNO}_2 / \mathrm{HCl}$, which yields an optically active alcohol. So, ' $C$ ' is aliphatic amine.
(iv) ' $A$ ' on ozonolysis produces 2 moles of $\mathrm{CH}_3 \mathrm{CHO}$. So, ' $A$ ' is $\mathrm{CH}_3-\mathrm{CH}=\mathrm{CH}-\mathrm{CH}_3$ (But-2-ene).
Reactions
A colourless substance ' A ' $\left(\mathrm{C}_6 \mathrm{H}_7 \mathrm{~N}\right)$ is sparingly soluble in water and gives a water soluble compound ' B ' on treating with mineral acid. On reacting with $\mathrm{CHCl}_3$ and alcoholic potash ' A ' produces an obnoxious smell due to the formation of compound ' C '. Reaction of ' A ' with benzenesulphonyl chloride gives compound ' D ' which is soluble in alkali. With $\mathrm{NaNO}_2$ and HCl , 'A' forms compound ' E ' which reacts with phenol in alkaline medium to give an orange dye ' $F$ '. Identify compounds ' $A$ ' to ' $F$ '.
