Question 1

Select the reagents that reduce nitriles to primary amines : A. (i) LiAlH _4; (ii) H _2 O B. Sn + HCl C. H _2/ Ni D. Na(Hg) / C _2 H _5 OH E. Br _2/ aq. NaOH Choose the correct answer from the options

Accepted Answer

Nitriles (R-CN) can be reduced to primary amines (R-CH_2NH_2) using strong reducing agents or catalytic hydrogenation. Reagent A: LiAlH _4 followed by hydrolysis is a strong reducing agent that reduces nitriles to primary amines. Reagent C: H _2/ Ni (catalytic hydrogenation) reduces nitriles to primary amines. Reagent D: Na(Hg) / C _2 H _5 OH (Mendius reduction) provides nascent hydrogen and reduces nitriles to primary amines. Reagent B: Sn + HCl is typically used to reduce nitro compounds to am

Question 2

Identify the reactions which give aniline as the major product. Choose the correct answer from the options given below.

Accepted Answer

Let us analyze each reaction to determine the major product: Reaction A: Benzonitrile (C_6H_5CN) is reduced by LiAlH_4, a strong reducing agent, to form benzylamine. C_6H_5CN LiAlH_4 C_6H_5CH_2NH_2 Reaction B: Benzamide (C_6H_5CONH_2) undergoes Hoffmann bromamide degradation in the presence of KOH and Br_2 to form aniline. C_6H_5CONH_2 KOH, Br_2 C_6H_5NH_2 Reaction C: Nitrobenzene (C_6H_5NO_2) is not reduced to aniline by NaBH_4. NaBH_4 is a mild reducing agent and generally does not reduce the

Question 3

The major product Z formed in the following sequence of reactions is : C _2 H _6 [ UV light ] Cl _2 X NH _3 Y [( monochlorinated product )] (i) NaNO _2/ HCl \ \ (ii) H _2 O Z

Accepted Answer

Ethane undergoes free radical halogenation with chlorine in the presence of UV light to form ethyl chloride (X). C _2 H _6 + Cl _2 UV light C _2 H _5 Cl \ (X) Ethyl chloride reacts with ammonia via nucleophilic substitution to form ethylamine (Y). C _2 H _5 Cl + NH _3 C _2 H _5 NH _2 \ (Y) Ethylamine, being a primary aliphatic amine, reacts with nitrous acid ( NaNO _2 + HCl ) to form an unstable aliphatic diazonium salt, which decomposes to yield a carbocation. The carbocation reacts with water

Question 4

The correct order of decreasing basic strength of the given amines is :

Accepted Answer

Basic strength order N -ethylethanamine > Ethanamine > N-methylaniline > Benzenamine

Question 5

Given below are two statements : Statement I : Benzenediazonium salt is prepared by the reaction of aniline with nitrous acid at 273-278 K. It decomposes easily in the dry state. Statement II : Insert

Accepted Answer

Benzenediazonium chloride is a colourless crystalline solid. It is readily soluble in water and is stable in cold but reacts with water when warmed. It decomposes easily in the dry state.

Question 6

The compound that does not undergo Friedel-Crafts alkylation reaction but gives a positive carbylamine test is :

Accepted Answer

For positive carbylamine test, there must be the presence of primary amine.

Question 7

Identify the major product C formed in the following reaction sequence:

Accepted Answer

- Step-I is S _ N reaction with C N nucleophile. - Step-Il will give amide. - Step-III is Hoffmann bromamide degradation reaction.

Question 8

Given below are two statements: Statement I : Aniline does not undergo Friedel-Crafts alkylation reaction. Statement II : Aniline cannot be prepared through Gabriel synthesis. In the light of the abov

Accepted Answer

- Aniline does not undergo Friedel-Crafts alkylation reaction due to salt formation with aluminium chloride, the Lewis acid, which is used as a catalyst. - Aniline (aromatic primary amine) cannot be prepared by Gabriel phthalimide synthesis because aryl halides do not undergo nucleophilic substitution with anion formed by phthalimide.

Question 9

Select the incorrect reaction among the following:

Accepted Answer

Answer option index: 1

Amines — Previous Year Questions & Solutions