Chemistry NCERT Exemplar Solutions Class 12th Chapter Thirteen

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (C) 

Using active metals like iron in acidic conditions can be efficiently used for the reduction of nitro compounds. 

Under the acidic conditions, the intermediate compounds that may form are readily reduced to primary amine and pure product of primary amine is obtained. 

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (C)

In the process of nitration of benzene, firstly H₂SO₄ dissociates into H⁺ and HSO₄−. The proton produced further reacts with HNO₃ to give a positively charged complex that is unstable and dissociates into nitronium ions and water as products. The nitronium ion is an electron-deficient species i.e. electrophile that attacks the electron cloud of the benzene ring.

H₂SO₄  (conc.) ? H⁺+HSO₄⁻

H⁺+HNO₃? H₂NO₃⁺

H₂NO₃⁺? NO₂⁺ + H2O

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (B) 

Primary aliphatic amines react with nitrous acid to form aliphatic diazonium salts, which are unstable and release nitrogen gas and alcohol quantitatively.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (C)

Methyl amine reacts with HNO₃ form methanol with release of nitrogen gas and water as side products.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (D) 

The greater the electron density towards the ring, the greater its basic strength.

The electron withdrawing group reduces basic strength, whereas the electron donating group increases basic strength.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (B) 

Hoffmann invented a method for producing primary amines by treating an amide with bromine in an aqueous or ethanolic sodium hydroxide solution. An alkyl or aryl group migrates from the amide's carbonyl carbon to the nitrogen atom during this degradation reaction.

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Ans: (B) 

Hoffmann bromamide reaction- it is also called degradation reaction as in this reaction primary amide group is treated with halogen first (Br) then the halogen-substituted amide product is converted to a primary amine with the release of carbon dioxide gas.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (D)

Lithium aluminium hydride in ether is a strong reducing agent that donates its hydride ion to any C=O containing functional groups into corresponding reduced compounds. Here, the amide group is converted to an amine functional group.

LiAlH₄ in ether is the best reagent for converting 2-phenylpropanamide to 2-phenylpropanamine.

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: ( C)

This is a Multiple Choice Questions as classified in NCERT Exemplar

Ans: (D)

Gabriel synthesis reaction:  

Gabriel's synthesis is a method for producing primary amines. When phthalimide is treated with ethanolic potassium hydroxide, it forms a potassium salt of phthalimide, which when heated with an alkyl halide and then alkaline hydrolyzed yields the corresponding primary amine. This method cannot produce aromatic primary amines because aryl halides do not undergo nucleophilic substitution with the anion formed by phthalimide.