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Questions:

Generic 2

12 x 2 = 24

What is diazotisation? Why are benzenediazonium salts more stable than alkanediazonium salts?

Name reagents required for preparation of methyl orange indicator (no reaction).

Give an example of Gomberg reaction.

Write the structure of benzenediazonium chloride.

Name one reagent used for the separation of primary, secondary and tertiary amines.

What amine salts are used for determining their molecular masses?

How will you distinguish between (CH₃)₂NH and (CH₃)₃N?

Arrange the following in decreasing order of their basic strength:
C₆H₅NH₂, C₂H₅NH₂, (C₂H₅)₂ NH, NH₃

How will you bring about the following conversions?
(i) Ethanamine to Ethanoic acid
(ii) Aniline to Benzonitrile

10.

Give a chemical test to distinguish between aniline and N-methlaniline.

11.

Why do amines react as nucleophiles?

12.

Give the IUPAC name of
H₂N-CH₂-CH₂-CH = CH₂

Generic 3

4 x 3 = 12

13.

Give the structures of A, B and C in the following reaction:
(a) \({ C }_{ 6 }{ H }_{ 5 }{ NO }_{ 2 }\overset { Fe/HCI }{ \longrightarrow } A\overset { { HNO }_{ 2 };273K }{ \longrightarrow } B\overset { { C }_{ 6 }{ H }_{ 5 }{ OH } }{ \longrightarrow } C\)
(b) \({ C }_{ 6 }{ H }_{ 5 }{ N }_{ 2 }CI\overset { CuCN }{ \longrightarrow } A\overset { { H }_{ 2 }O/{ H }^{ + } }{ \longrightarrow } B\overset { { NH }_{ 3 };\triangle }{ \longrightarrow } C\)

14.

A colourless substance 'A' (C₆H₇N) is sparingly soluble in water and gives a water soluble compound 'B' on treating with mineral acid. On reacting with CHCl₃ and alcoholic potash 'A' produces an obnoxious smell due to the formation of compoung 'C'. Reaction of 'A' with benzenesulphonyl chloride gives compound 'D' which is soluble in alkali. With NaNO₂ and HCl, 'A' forms compound 'E' which reacts with phenol in alkaline medium to give an orange dye 'F' . Identify compounds 'A' to 'F'.

15.

Carry out following conversions:
(a) Toluene to m-bromotoluene
(b) Benzene to m-bromoaniline

16.

An aliphatic compound 'A' with molecular formula C₂H₃Cl on treatment with AgCN hives two isomeric compounds of unequal amounts with the molecular formula C₃H₃N. The minor of nthese two products on complete reduction with H₂in the presence of Ni gives a compound 'B' with molecular formula C₃H₉N. Identify the compounds 'A' , 'B' and write the reactions involved.

Multiple Choice Question

10 x 1 = 10

17.

A positive carbylamine test is given by

(a)

N, N-dimethylaniline

(b)

2, 4-dimethylaniline

(c)

N-methyl-o-methylaniline

(d)

p-methylbenzylamine

18.

The correct sequence of reactions to convert p-nitrophenol into quinol involves

(a)

reduction, diazotization and hydrolysis

(b)

hydrolysis, diazotization and reduction

(c)

hydrolysis, reduction and diazotization

(d)

diazotization, reduction and hydrolysis

19.

Which on e of the following amines cannot be prepared by Gabriel phthalimide synthesis?

(a)

Ethylamine

(b)

Isopropylamine

(c)

n-Propylamine

(d)

Ethylmethylamine

20.

The total number of structural isomers possible for an amine with molecular formula C₄H₁₁N is

(a)

(b)

(c)

(d)

(e)

21.

Nitrobenzene on reaction with conc.HNO₃/H₂SO₄ at 80-\({ 100 }^{ \circ }\)C forms which one of the following products?

(a)

1, 4-Dinitrobenzene

(b)

1, 2, 4-Trinitrobenzene

(c)

1,2-Dinitrobenzene

(d)

1, 3-Dinitrobenzene

22.

The best reagent for converting, 2-phenylpropanamide into 1-phenylethanamine is.................................. .

(a)

excess H₂/Pt

(b)

NaOH/Br₂

(c)

NaBH₄/methanol

(d)

LiAIH₄/ether

23.

Which of the following reagents would not be a good choice for reducing an aryl nitro compound to an amine?

(a)

H₂ (excess) / Pt

(b)

LiAIH₄ in ether

(c)

Fe and HCI

(d)

Sn and HCI

24.

Which of the following will not show coupling reaction with benzenediazonium chloride?

(a)

Aniline

(b)

Phenol

(c)

2-Naphthol

(d)

Benzyl alcohol

25.

When a primary amine reacts with chloroform and ethanolic KOH, then the product formed is

(a)

isocyanide

(b)

aldehyde

(c)

cyanide

(d)

alcohol

26.

Which of the following reactions will not give a primary amine?

(a)

\({ CH }_{ 3 }CON{ H }_{ 2 }\overset { { Br }_{ 2 }/KOH }{ \longrightarrow } \)

(b)

\({ CH }_{ 3 }CN\overset { { LiAiH }_{ 4 } }{ \longrightarrow } \)

(c)

\({ CH }_{ 3 }NC\overset { { LiAiH }_{ 4 } }{ \longrightarrow } \)

(d)

\({ CH }_{ 3 }{ CONH }_{ 2 }\overset { { LiAiH }_{ 4 } }{ \longrightarrow } \)

Generic 5

1 x 5 = 5

27.

Why is an amide more acidic than amine?

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Answers Key:

Generic 2

12 x 2 = 24

The reaction/process of converting aromatic primary amines into diazonium salts by treatment with a solution of nitrous acid (produced, in situ, by the action of dilute HCI on sodium nitrite) at 273-278 K is called diazotisation. For example,
\({ NaNO }_{ 2 }+HCl\longrightarrow { HNO }_{ 2 }+NaCl\\ { C }_{ 6 }{ H }_{ 5 }-{ NH }_{ 2 }+{ HNO }_{ 2 }+HCl\overset { 273-278K }{ \underset { (Diazotisation) }{ \longrightarrow } } { C }_{ 6 }{ H }_{ 5 }-\overset { + }{ N } \equiv { NCl }^{ - }+2{ H }_{ 2 }O\)

Reagents required are:
(i) sulphanilic acid
(ii) N, N-dimethylaniline
(iii) NaNO₂ HCI and
(iv) a base.

The reaction of benzenediazonium salts with benzene or bromobenzene or nitrobenzene in aqueous alkali to afford the corresponding biphenyl derivatives is called Gomberg rection.

\(\mathrm{C}_6 \mathrm{H}_5-\stackrel{+}{\mathrm{N}} \equiv \mathrm{NCl}^{-}\)

HInsberg's reagent (C₆H₅SO₂CI)

Chloroplatinates. For example, (RN+H₃)₂PtCI₆²⁻

These can be distinguished by Liebermann nitromann nitrosoamine reaction.(CH₃ )₂NH On treatment with HNO₂ (generated in situ by the action of dil.HCL on NaNO₂ ) gives yellow coloured oily N-nitrosodimethylamin.
\({ \left( { CH }_{ 3 } \right) }_{ 2 }NH+HO-N=O\longrightarrow { \left( { CH }_{ 3 } \right) }_{ 2 }N-N=O+{ H }_{ 2 }O\\ \quad Dimethylamine\quad \quad \quad \quad \quad \quad \quad \quad \quad N-Nitrosodimethylamine\)
N-Nitrosodiethylamine on warming with a crystal of phenol and cone. H2S04 gives a green solution which when made alkaline with aqueous NaOH turns deep blue and then red on dilution.
(CH₃)₃N (trimethylame) on the other hand, being a 3° does not give this test.

The decreasing order of basic strength of the given amines and ammonia follows the following order:
(C₂H₅)NH > C₂H₅NH₂ > NH₃ > C₆H₅NH₂

10.

Add CHCl₃ and KOH. Aniline will give offensive smell due to formation of phenyl carbylamine (phenyl isocyanide), where as N-methylaniline will not react.

11.

It is due tp presence of lone pair of electronson nitrogen which they can donate and act as nucleophiles.

12.

But-3-en-1-amine.

Generic 3

4 x 3 = 12

13.

(i) \(A-{ C }_{ 6 }{ H }_{ 5 }{ NH }_{ 2 },\quad B-{ C }_{ 6 }{ H }_{ 5 }{ N }_{ 2 }^{ + }C{ I }^{ - },C-{ C }_{ 6 }{ H }_{ 5 }{ -N }_{ 2 }-{ C }_{ 6 }{ H }_{ 4 }OH\)
(ii) \(A-{ C }_{ 6 }{ H }_{ 5 }CN,\quad B-{ C }_{ 6 }{ H }_{ 5 }NCOOH,\quad C-{ C }_{ 6 }{ H }_{ 5 }{ CONH }_{ 2 }\)

14.

15.

16.

Multiple Choice Question

10 x 1 = 10

17.

2, 4-Dimethylaniline and p-methylbenzylamine are \({ 1 }^{ \circ }\) amines and hence give positive carbylamine test.

18.

(a)
reduction, diazotization and hydrolysis

19.

Only \({ 1 }^{ \circ }\) amines can be prepared by Gabriel phthalimide reaction. Therefore, ethylmethylamine being \({ 2 }^{ \circ }\) cannot be prepared by this method.

20.

(e)
8

21.

-NO₂ is a m-directing group and hance 1, 3-dinitrobenzene is formed.

22.

(b)
NaOH/Br₂

23.

(b)
LiAIH₄ in ether

24.

only aromic \({ 1 }^{ \circ }\)amines and phenols show coupling reaction.

25.

Carbylamine reaction yields isocyanides.

26.

Generic 5

1 x 5 = 5

27.

The amide has the following resonating structures:

Due to the delocalisation of lone pair of electrons on N over C==O group, amino group acquires a positive charge which ma, es N-H bond weak. Moreover, the anion formed after removal of a proton is also stabilized by resonance as :

However, no such stabilization is possible in amines.