Ncert Solutions Chemistry Class 12th

(i) Aromatic amines react with nitrous acid (prepared in situ from NaNO₂and a mineral acid such as HCl) at 273 - 278 K to form stable aromatic diazonium salts e., NaCl and water.

(ii) Aliphatic primary amines react with nitrous acid (prepared in situ from NaNO₂and a mineral acid such as HCl) to form unstable aliphatic diazonium salts, which further producealcohola and acid called as hydrochloric acid and evolution of nitrogen

(iii) Aliphatic amines are stronger bases than aromatic amines due to following reasons:

(a) The lone pair of electrons of the nitrogen atom of aromatic amines is involved in

conjugation with the π−bond pairs of the ring as follows

(b) Anilinium ion obtained by accepting a proton is less stabilized by resonance. Due to the −R effect of the benzene ring, the electrons on the N- atom are less available in the case of aromatic amines. Therefore, the electrons on the N-atom in aromatic amines cannot be donated

So, aniline is a weaker base than alkyl amines, in which +1 effect increases the electron density on the nitrogen atom.

1- C₆H₅NH₂ + CHCl₃ + KOH

It is a carbylamine reaction in which a isocyanide compound is formed along with side products of potassium chloride.Basically the name of reaction is given is due to formation of a foul smelling compound called as isocyanide.

2- C₆H₅N₂Cl + H₃PO₂ + H₂O

Benzenediazonium chloride is a very reactive compound which oxidises hypophosphorous acid to hypophosphoric acid and the reactant is reduced to benzene.

3- C₆H₅NH₂ + H₂SO₄ (conc.)

Aniline undergoes sulphonation to anillium hydrogensulphate.

4- C₆H₅N₂Cl + C₂H₅OH

Aniline is very activating group which undergoes reaction to give ortho and para product. But in acidic medium aniline accquires positive charge on N atom which is metadirecting group and hence the product.

5- C₆H₅NH₂ + Br₂ (aq)

It is clubbing reaction of a very reactive compound undergoing addition to give benzene.

6- C₆H₅NH₂ + (CH₃CO)₂O

As mentioned aniline is avery activating group, so to reduce its activity it is reacted with anhydride to give n-phenylethanamine.

7- C₆H₅N₂Cl

Hydrofluroburic acid reacts qith benzenediazonium chloride along with sodium nitrite to give a reduced product as Nitrobenzene.

(i) Ethyl iodide reacts with NaCN gives a substitution reactions to give propanitrile upon partial hydrolysis gives B, upon reaction with sodium hydroxide gives C.

(ii) Benzenediazoniumchloride gives nucleophilic substitution reactions gives A, upon hydrolysis the CN ion is replaced by OH ion which is less better leaving group gives B upon heating with ammonia gives C.

(iii) Ethylbromide gives nucleophilic substitution reactions gives B, upon reduction gives B followed by reacting with nitrous acid, i.e oxidation gives propanol.

(iv) Nitrobenzene upon reduction with iron/acid gives A, reacting with sodium nitrite gives benzenediazonium chloride, followed by complete Hydrolysis gives phenol.

(v) Acetic acid upon heating with ammmonia gives A, which is an amide. This amide reacts with NaOBr which extracts the carbonyl carbon giving B, followed by reacting with sodium nitrite gives methanol.

(vi) Nitrobenzene upon reduction with iron/acid mixture gives A, followed by oxidation with nitrous acid gives B and reacting with phenol undergoes addition reaction to give C.