Chemistry

Amines

Question:

Under what reaction conditions (acidic/basic), the coupling reaction of aryl diazonium chloride with aniline is carried out?

Answer:

Coupling reaction of aryl diazonium chloride with aniline is carried out in mild acidic condition (pH = 4-5).

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Amines

Q 1.

Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.

Q 2.

Under which of the following reaction conditions, aniline gives p-nitro derivative as the major product?
(a) Acetyl chloride/pyridine followed by reaction with cone. H2SO4 + cone.
(b) Acetic anhydride/pyridine followed by cone. H2SO4 + cone. HNO3
(c) Dil. HCl followed by reaction with cone. H2SO4 + cone. HNO3
(d) Reaction with cone. HNO3 + cone. H2S04

Q 3.

Which of the following is the weakest Bronsted base?
ncert-exemplar-problems-class-12-chemistry-amines-3

Q 5.

Why is benzene diazonium chloride not stored and is used immediately after its preparation?

Q 6.

How will you carry out the following conversion?
ncert-exemplar-problems-class-12-chemistry-amines-64

Q 7.

Which of the following compounds is the weakest Bronsted base?
ncert-exemplar-problems-class-12-chemistry-amines-24

Q 8.

Which of the following reactions belong to electrophilic aromatic substitution?
(a) Bromination of acetanilide
(b) Coupling reaction of aryldiazonium salts
(c) Diazotisation of aniline
(d) Acylation of aniline

Q 9.

Assertion (A): N, N-diethylbenzene sulphonamide is insoluble in alkalf. Reason (R): Sulphonyl group attached to nitrogen atom is strong electron withdrawing group.

Q 10.

Which of the following should be most volatile?
ncert-exemplar-problems-class-12-chemistry-amines-26

Q 11.

Complete the following acid-base reactions and name the products:
(i) CH3CH2CH2NH2+HCl ——–>
(ii) (C2H5)3 N+HCl ——–>

Q 12.

Predict the reagent or the product in the following reaction sequence.
ncert-exemplar-problems-class-12-chemistry-amines-80

Q 13.

Reduction of nitrobenzene by which of the following reagents give aniline?
(a) Sn/HCl (b) Fe/HCl (c) H2-Pd (d) Sn/NH4OH

Q 14.

How wjll you convert:
(i) Ethanoic acid into methanamine (ii) Hexanenitrile into 1-aminopentane
(iii) Methanol to ethanoic acid. (iv) Ethanamine into methanamine
(v) Ethanoic acid into propanoic acid (vi) Methanamine into ethanamine
(vii) Nitromethane into dimethylamine (viii) Propanoic acid into ethanoic acid?

Q 15.

Account for the following
(i)pKb of aniline is more than that of methylamine
(ii) Ethylamine is soluble in water whereas aniline is not.
(iii) Methylamine in water reacts with ferric chloride to precipitate hydrated ferric oxide.
(iv)Although amino group is o and p – directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of m-nitroaniline.
(v)Aniline does not undergo Friedel-Crafts reaction.
(vi)Diazonium salts of aromatic amines are more stable than those of aliphatic amines.
(vii)Gabriel phthalimide synthesis is preferred for synthesising primary amines.

Q 16.

Why does acetylation of -NH2 group of aniline reduce its activating effect?

Q 17.

Predict the product of reaction of aniline with bromine in non-polar solvent such as CS2.

Q 18.

Give the structures of A,B and C in the following reaction:
ncert-solutions-for-class-12-chemistry-amines-34
ncert-solutions-for-class-12-chemistry-amines-35

Q 19.

Give plausible explanation for each of the following:
(i) Why are amines less acidic than alcohols of comparable molecular masses?
(ii) Why do primary amines have higher boiling point than tertiary amines?
(iii) Why are aliphatic amines stronger bases than aromatic amines?

Q 20.

The correct increasing order of basic strength for the following compounds is
ncert-exemplar-problems-class-12-chemistry-amines-13

Q 21.

Among the following amines’ the strongest Bronsted base is
ncert-exemplar-problems-class-12-chemistry-amines-25

Q 22.

The best reagent for converting 2-phenylpro-panamide into-2-phenyl- propanamine is .
(a) excess H2
(b) Br2 in aqueous NaOH
(c) iodine in the presence of red phosphorus
(d) LiAlH4 in ether

Q 23.

Arrange the following in increasing order of their basic strength: ‘
(i) C2H5NH2,C6H5NH2,NH3,C6H5CH2NH2 and(C2H5)2 NH
(ii) C2H5NH2,(C2H5)2NH,(C2H5)3N,C6H5NH2
(iii) CH3NH2, (CH3)2NH, (CH3)3N, C6H5NH2, C6H5CH2NH2

Q 24.

Explain why is MeNH2 stronger base than MeOH?

Q 25.

How will you bring out the following conversion?
ncert-exemplar-problems-class-12-chemistry-amines-62

Q 26.

Assertion (A): Only a small amount of HCl is required in the reduction of nitro compounds with iron scrap and HCl in the presence of steam.
Reason (R): FeCl2 formed gets hydrolysed to release HCl during the reaction.

Q 27.

Which of the following species are involved in the carbylamine test?
(a) R-NC (b) CHCl3 (c) COCl2 (d) NaN02 + HCl

Q 28.

A compound Z with molecular formula C3H9N reacts with C6H5SO2Cl to give a solid, insoluble in alkali, identify Z.

Q 29.

Identify A and B in the following reaction.
ncert-exemplar-problems-class-12-chemistry-amines-57

Q 30.

Assertion (A): Hofmann's bromamide reaction is given by primary amines. Reason (R): Primary amines are more basic than secondary amines.

Q 31.

Write short notes on the following:
(i) Carbylamine reaction (il) Diazotisation (iii) ‘Hofmann's bromamide reaction
(iv) Coupling reaction (v) Ammonolysis (vi) Acetylation
(vii) Gabriel phthalimide synthesis

Q 32.

Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?

Q 33.

Which of the following is a 3 ° amine?
(a) 1 -Methylcyclohexylamine (c) tert-Butylamine

Q 34.

What is the role of pyridine in the acylation reaction of amines?

Q 35.

Write down the IUPAC name of
ncert-exemplar-problems-class-12-chemistry-amines-49

Q 36.

A solution contains 1 g mol each of p-toluene diazonium chloride and p-nitrophenyl diazonium chloride. To this 1 g mol of alkaline solution of phenol is added. Predict the major product. Explain your answer.

Q 37.

The best reagent for converting-2-phenylpro-panamide into 1-phenylethana- mine is .
(a) excess H2/Pt (b) NaOH /Br2
(c) NaBH4/methanol (d) LiAlH4/ether

Q 38.

Why is NH2 group of aniline acetylated before carrying out nitration?

Q 39.

Match the compounds given in Column I with the items given in Column II.
ncert-exemplar-problems-class-12-chemistry-amines-73

Q 40.

Write chemical reaction of aniline with benzoyl chloride and write the name of the product obtained.

Q 41.

Amongst the given set of reactants, the most appropriate for preparing 2 ° amine is .
(a) 2 ° R – Br + NH3
(b) 2 ° R – Br + NaCN followed by H2/Pt
(c) 10 R – NH2 + RCHO followed by H2/Pt
(d) 1 ° R – Br + (2 mol) + potassium phthalimide followed by H3O+/heat

Q 42.

Give the structure of 'A' in the following reaction.
ncert-exemplar-problems-class-12-chemistry-amines-44

Q 43.

What is the structure and IUPAC name of the compound, allyl amine?

Q 44.

Assertion (A): Aromatic 1 ° amines can be prepared by Gabriel phthalimide synthesis.
Reason (R): Aryl halides undergo nucleophilic substitution with anion formed by phthalimide.

Q 45.

Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary  amines.  
(i) (CH3)2 CHNH2 (ii) CH3(CH2)2NH2 (iii) CH3NHCH(CH3)2
(iv) (CH3)3 CNH2 (v) C6H5NHCH3(vi) (CH3CH2)2NCH3
(vii)m-BrC6H4NH2

Q 46.

An aromatic compound 'A'on treatment with aqueous ammonia and heating forms compound 'B' which on heating with Br2 and KOH forms a compound 'C' of molecular formula C6H7N. Write the structures and IUPAC names of compounds A,B and C.

Q 47.

Give plausible explanation for each of the following:
(i) Why are amines less acidic than alcohols of comparable molecular masses?
(ii) Why do primary amines have higher boiling point than tertiary amines?
(iii) Why are aliphatic amines stronger bases than aromatic amines?

Q 48.

The correct IUPAC name for CH2 = CHCH2NHCH3 is
(a) allylmethylamine (b) 2-amino-4-pentene
(c) 4-aminopent-l-ene . (d) N-methylprop-2-en-l-amine.

Q 49.

The reagents that can be used to convert benzene diazonium chloride to benzene are
(a) SnCl2/HCl (b) CH3CH2OH
(c) H3PO2 (d) LiAlH4

Q 50.

The Product of the following reaction is .
ncert-exemplar-problems-class-12-chemistry-amines-32