(i) Aryl cyanide cannot be prepared in this method because of their less reactivity towards nucleophilic substitution. Aryl cyanides are prepared using Sandmeyers reactions.
\(KCH+\underset { methyl \ bromide }{ { CH }_{ 3 }-Br } \rightarrow \underset { ethanenitrile }{ { CH }_{ 3 }-CN } +KBr\)
(ii) By dehydration' of primary amides a aldoximes with P₂O₅
\(\underset { Acetamide }{ { CH }_{ 3 }-CO{ NH }_{ 2 } } \xrightarrow [ { -H }_{ 2 }O ]{ { P }_{ 2 }{ O }_{ 5 } } \underset { Ethaneitrile }{ { CH }_{ 3 }-{ CN } } \)
(iii) \(\underset { Acetaldoximes }{ { CH }_{ 3 }-CH=NOH } \xrightarrow [ { -H }_{ 2 }O ]{ { P }_{ 2 }{ O }_{ 5 } } \underset { Ethaneitrile }{ { CH }_{ 3 }-{ CN } } \)

To get para product, the - NH₂ group is protected by acetylation with acetic anhydride. Then, the nitrated product is hydrolysed to form the product.

To get mono bromo compounds, -NH₂ is first acylated to reduce its activity.

(i) p-nitroaniline is prepared from aniline in three stages as follows:

(ii) 
 

(i) An organic compound (A) with molecular formula C₆H₇N is identified as Aniline C₆H₅NH₂
(ii) Aniline on treatment with HNO₂ / HCl at 273 K gives a clear solution of Benzene diazonium chloride C₆H₅N₂CI the compound (B).
\({ C }_{ 6 }{ H }_{ 5 }{ NH }_{ 2 }+{ HNO }_{ 2 }\xrightarrow [ 273K ]{ NCl } \underset { Benzene \ diazonium \ chloride }{ { C }_{ 6 }{ H }_{ 5 }{ N }_{ 2 }Cl } \)
(iii) An aqueous solution of benzene diazonium chloride on heating gives phenol C₆H₅OH and it is compound (C).
\({ C }_{ 6 }{ H }_{ 5 }{ N }_{ 2 }Cl+{ HOH }\underrightarrow { \triangle } { C }_{ 6 }{ H }_{ 5 }OH-{ N }_{ 2 }+HCl\)