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Chemistry · Textbook solutions

Amines

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 28 questions

Worked Examples

5 q

Solved Examples

Worked · 5
  1. Eg 9.1
    Write chemical equations for the following reactions: (i) Reaction of ethanolic NH3\text{NH}_3 with C2H5Cl\text{C}_2\text{H}_5\text{Cl}. (ii) Ammonolysis of benzyl chloride and reaction of amine so formed with two moles of CH3Cl\text{CH}_3\text{Cl}.
  2. Eg 9.2
    Write chemical equations for the following conversions: (i) CH3−CH2−Cl\text{CH}_3-\text{CH}_2-\text{Cl} into CH3−CH2−CH2−NH2\text{CH}_3-\text{CH}_2-\text{CH}_2-\text{NH}_2 (ii) C6H5−CH2−Cl\text{C}_6\text{H}_5-\text{CH}_2-\text{Cl} into C6H5−CH2−CH2−NH2\text{C}_6\text{H}_5-\text{CH}_2-\text{CH}_2-\text{NH}_2
  3. Eg 9.3
    Write structures and IUPAC names of (i) the amide which gives propanamine by Hoffmann bromamide reaction. (ii) the amine produced by the Hoffmann degradation of benzamide.
  4. Eg 9.4
    Arrange the following in decreasing order of their basic strength: C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, C2H5NH2\text{C}_2\text{H}_5\text{NH}_2, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH}, NH3\text{NH}_3
  5. Eg 9.5
    How will you convert 4-nitrotoluene to 2-bromobenzoic acid?

Intext Questions

9 q
  1. Intext 9.1
    Classify the following amines as primary, secondary or tertiary: (i) C10H7−NH2\text{C}_{10}\text{H}_7-\text{NH}_2 (naphthalene carrying the −NH2-\text{NH}_2 group at position 1) (ii) C10H7−N(CH3)2\text{C}_{10}\text{H}_7-\text{N}(\text{CH}_3)_2 (naphthalene carrying the −N(CH3)2-\text{N}(\text{CH}_3)_2 group at position 1) (iii) (C2H5)2CHNH2(\text{C}_2\text{H}_5)_2\text{CHNH}_2 (iv) (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH}
  2. Intext 9.2
    (i) Write structures of different isomeric amines corresponding to the molecular formula, C4H11N\text{C}_4\text{H}_{11}\text{N}. (ii) Write IUPAC names of all the isomers. (iii) What type of isomerism is exhibited by different pairs of amines?
  3. Intext 9.3
    How will you convert (i) Benzene into aniline (ii) Benzene into N, N-dimethylaniline (iii) Cl−(CH2)4−Cl\text{Cl}-(\text{CH}_2)_4-\text{Cl} into hexan-1,6-diamine?
  4. Intext 9.4
    Arrange the following in increasing order of their basic strength: (i) C2H5NH2\text{C}_2\text{H}_5\text{NH}_2, C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, NH3\text{NH}_3, C6H5CH2NH2\text{C}_6\text{H}_5\text{CH}_2\text{NH}_2 and (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH} (ii) C2H5NH2\text{C}_2\text{H}_5\text{NH}_2, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH}, (C2H5)3N(\text{C}_2\text{H}_5)_3\text{N}, C6H5NH2\text{C}_6\text{H}_5\text{NH}_2 (iii) CH3NH2\text{CH}_3\text{NH}_2, (CH3)2NH(\text{CH}_3)_2\text{NH}, (CH3)3N(\text{CH}_3)_3\text{N}, C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, C6H5CH2NH2\text{C}_6\text{H}_5\text{CH}_2\text{NH}_2.
  5. Intext 9.5
    Complete the following acid-base reactions and name the products: (i) CH3CH2CH2NH2+HCl→\text{CH}_3\text{CH}_2\text{CH}_2\text{NH}_2 + \text{HCl} \rightarrow (ii) (C2H5)3N+HCl→(\text{C}_2\text{H}_5)_3\text{N} + \text{HCl} \rightarrow
  6. Intext 9.6
    Write reactions of the final alkylation product of aniline with excess of methyl iodide in the presence of sodium carbonate solution.
  7. Intext 9.7
    Write chemical reaction of aniline with benzoyl chloride and write the name of the product obtained.
  8. Intext 9.8
    Write structures of different isomers corresponding to the molecular formula, C3H9N\text{C}_3\text{H}_9\text{N}. Write IUPAC names of the isomers which will liberate nitrogen gas on treatment with nitrous acid.
  9. Intext 9.9
    Convert (i) 3-Methylaniline into 3-nitrotoluene. (ii) Aniline into 1,3,5 - tribromobenzene.

Exercises

14 q
  1. Ex 9.1
    Write IUPAC names of the following compounds and classify them into primary, secondary and tertiary amines. (i) (CH3)2CHNH2(\text{CH}_3)_2\text{CHNH}_2 (ii) CH3(CH2)2NH2\text{CH}_3(\text{CH}_2)_2\text{NH}_2 (iii) CH3NHCH(CH3)2\text{CH}_3\text{NHCH}(\text{CH}_3)_2 (iv) (CH3)3CNH2(\text{CH}_3)_3\text{CNH}_2 (v) C6H5NHCH3\text{C}_6\text{H}_5\text{NHCH}_3 (vi) (CH3CH2)2NCH3(\text{CH}_3\text{CH}_2)_2\text{NCH}_3 (vii) m−BrC6H4NH2m-\text{BrC}_6\text{H}_4\text{NH}_2
  2. Ex 9.2
    Give one chemical test to distinguish between the following pairs of compounds. (i) Methylamine and dimethylamine (ii) Secondary and tertiary amines (iii) Ethylamine and aniline (iv) Aniline and benzylamine (v) Aniline and N-methylaniline.
  3. Ex 9.3
    Account for the following: (i) pKb\text{p}K_b 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−o- and p−p- directing in aromatic electrophilic substitution reactions, aniline on nitration gives a substantial amount of mm-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.
  4. Ex 9.4
    Arrange the following: (i) In decreasing order of the pKb\text{p}K_b values: C2H5NH2\text{C}_2\text{H}_5\text{NH}_2, C6H5NHCH3\text{C}_6\text{H}_5\text{NHCH}_3, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH} and C6H5NH2\text{C}_6\text{H}_5\text{NH}_2 (ii) In increasing order of basic strength: C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, C6H5N(CH3)2\text{C}_6\text{H}_5\text{N}(\text{CH}_3)_2, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH} and CH3NH2\text{CH}_3\text{NH}_2 (iii) In increasing order of basic strength: (a) Aniline, pp-nitroaniline and pp-toluidine (b) C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, C6H5NHCH3\text{C}_6\text{H}_5\text{NHCH}_3, C6H5CH2NH2\text{C}_6\text{H}_5\text{CH}_2\text{NH}_2. (iv) In decreasing order of basic strength in gas phase: C2H5NH2\text{C}_2\text{H}_5\text{NH}_2, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH}, (C2H5)3N(\text{C}_2\text{H}_5)_3\text{N} and NH3\text{NH}_3 (v) In increasing order of boiling point: C2H5OH\text{C}_2\text{H}_5\text{OH}, (CH3)2NH(\text{CH}_3)_2\text{NH}, C2H5NH2\text{C}_2\text{H}_5\text{NH}_2 (vi) In increasing order of solubility in water: C6H5NH2\text{C}_6\text{H}_5\text{NH}_2, (C2H5)2NH(\text{C}_2\text{H}_5)_2\text{NH}, C2H5NH2\text{C}_2\text{H}_5\text{NH}_2.
  5. Ex 9.5
    How will 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?
  6. Ex 9.6
    Describe a method for the identification of primary, secondary and tertiary amines. Also write chemical equations of the reactions involved.
  7. Ex 9.7
    Write short notes on the following: (i) Carbylamine reaction (ii) Diazotisation (iii) Hofmann's bromamide reaction (iv) Coupling reaction (v) Ammonolysis (vi) Acetylation (vii) Gabriel phthalimide synthesis.
  8. Ex 9.8
    Accomplish the following conversions: (i) Nitrobenzene to benzoic acid (ii) Benzene to mm-bromophenol (iii) Benzoic acid to aniline (iv) Aniline to 2,4,6-tribromofluorobenzene (v) Benzyl chloride to 2-phenylethanamine (vi) Chlorobenzene to pp-chloroaniline (vii) Aniline to pp-bromoaniline (viii) Benzamide to toluene (ix) Aniline to benzyl alcohol.
  9. Ex 9.9
    Give the structures of A, B and C in the following reactions: (i) CH3CH2I→NaCNA→Partial hydrolysisO−HB→NaOH+Br2C\text{CH}_3\text{CH}_2\text{I} \xrightarrow{\text{NaCN}} \text{A} \xrightarrow[\text{Partial hydrolysis}]{\overset{-}{\text{O}}\text{H}} \text{B} \xrightarrow{\text{NaOH} + \text{Br}_2} \text{C} (ii) C6H5N2Cl→CuCNA→H2O/H+B→ΔNH3C\text{C}_6\text{H}_5\text{N}_2\text{Cl} \xrightarrow{\text{CuCN}} \text{A} \xrightarrow{\text{H}_2\text{O}/\text{H}^{+}} \text{B} \xrightarrow[\Delta]{\text{NH}_3} \text{C} (iii) CH3CH2Br→KCNA→LiAlH4B→0 ∘CHNO2C\text{CH}_3\text{CH}_2\text{Br} \xrightarrow{\text{KCN}} \text{A} \xrightarrow{\text{LiAlH}_4} \text{B} \xrightarrow[0\,^\circ\text{C}]{\text{HNO}_2} \text{C} (iv) C6H5NO2→Fe/HClA→273 KNaNO2+HClB→ΔH2O/H+C\text{C}_6\text{H}_5\text{NO}_2 \xrightarrow{\text{Fe}/\text{HCl}} \text{A} \xrightarrow[273\ \text{K}]{\text{NaNO}_2 + \text{HCl}} \text{B} \xrightarrow[\Delta]{\text{H}_2\text{O}/\text{H}^{+}} \text{C} (v) CH3COOH→ΔNH3A→NaOBrB→NaNO2/HClC\text{CH}_3\text{COOH} \xrightarrow[\Delta]{\text{NH}_3} \text{A} \xrightarrow{\text{NaOBr}} \text{B} \xrightarrow{\text{NaNO}_2/\text{HCl}} \text{C} (vi) C6H5NO2→Fe/HClA→273 KHNO2B→C6H5OHC\text{C}_6\text{H}_5\text{NO}_2 \xrightarrow{\text{Fe}/\text{HCl}} \text{A} \xrightarrow[273\ \text{K}]{\text{HNO}_2} \text{B} \xrightarrow{\text{C}_6\text{H}_5\text{OH}} \text{C}
  10. Ex 9.10
    An aromatic compound 'A' on treatment with aqueous ammonia and heating forms compound 'B' which on heating with Br2\text{Br}_2 and KOH forms a compound 'C' of molecular formula C6H7N\text{C}_6\text{H}_7\text{N}. Write the structures and IUPAC names of compounds A, B and C.
  11. Ex 9.11
    Complete the following reactions: (i) C6H5NH2+CHCl3+alc.KOH→\text{C}_6\text{H}_5\text{NH}_2 + \text{CHCl}_3 + \text{alc.KOH} \rightarrow (ii) C6H5N2Cl+H3PO2+H2O→\text{C}_6\text{H}_5\text{N}_2\text{Cl} + \text{H}_3\text{PO}_2 + \text{H}_2\text{O} \rightarrow (iii) C6H5NH2+H2SO4 (conc.)→\text{C}_6\text{H}_5\text{NH}_2 + \text{H}_2\text{SO}_4\ (\text{conc.}) \rightarrow (iv) C6H5N2Cl+C2H5OH→\text{C}_6\text{H}_5\text{N}_2\text{Cl} + \text{C}_2\text{H}_5\text{OH} \rightarrow (v) C6H5NH2+Br2(aq)→\text{C}_6\text{H}_5\text{NH}_2 + \text{Br}_2(\text{aq}) \rightarrow (vi) C6H5NH2+(CH3CO)2O→\text{C}_6\text{H}_5\text{NH}_2 + (\text{CH}_3\text{CO})_2\text{O} \rightarrow (vii) C6H5N2Cl→(ii) NaNO2/Cu, Δ(i) HBF4\text{C}_6\text{H}_5\text{N}_2\text{Cl} \xrightarrow[(\text{ii})\,\text{NaNO}_2/\text{Cu},\,\Delta]{(\text{i})\,\text{HBF}_4}
  12. Ex 9.12
    Why cannot aromatic primary amines be prepared by Gabriel phthalimide synthesis?
  13. Ex 9.13
    Write the reactions of (i) aromatic and (ii) aliphatic primary amines with nitrous acid.
  14. Ex 9.14
    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?