Chemistry · Textbook solutions

Basic Principles of Organic Chemistry

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 64 questions

14. Basic Principles of Organic Chemistry — worked examples

11 q

Solved Examples

Worked · 11
  1. Solved Ex.14.1
    Alkanes constitute a homologous series of straight chain saturated hydrocarbons. Write down the structural formulae of the first five homologues of this series. Write their molecular formulae and deduce the general formula of such homologous series.
  2. Solved Ex.14.2
    Write down structural formulae of (a) the third higher and (b) the second lower homologue of CH3CH2COOH\mathrm{CH_3CH_2COOH}.
  3. Solved Ex.14.3
    Complete the following table.
    Structural formulaNumberingPrefixIUPAC Name
    CH3−CHCH3−CH2−CH3\mathrm{CH_3-\underset{CH_3}{CH}-CH_2-CH_3}C1−C2C−C3−C4\mathrm{\overset{1}{C}-\underset{C}{\overset{2}{C}}-\overset{3}{C}-\overset{4}{C}}2 - methyl2 - methylbutane
    CH3−CCH3CH3−CH3\mathrm{CH_3-\underset{CH_3}{\overset{CH_3}{C}}-CH_3}C1−CCC2−C3\mathrm{\overset{1}{C}-\underset{C}{\overset{C}{C}}^{2}-\overset{3}{C}}2, 2 - dimethyl2, 2-dimethylpropane
    CH3−CHCH3−CHCH3−CH2CH3\mathrm{CH_3-\underset{CH_3}{CH}-\underset{CH_3}{CH}-\underset{CH_3}{CH_2}}
    CH3−CHCH3−CHCH2−CH3−CH2−CH2−CH3\mathrm{CH_3-\underset{CH_3}{CH}-\underset{CH_2-CH_3}{CH}-CH_2-CH_2-CH_3}
    CH3−CHC2H5−CHC2H5−CH2−CH2−CH3\mathrm{CH_3-\underset{C_2H_5}{CH}-\underset{C_2H_5}{CH}-CH_2-CH_2-CH_3}
    C(C2H5)4\mathrm{C(C_2H_5)_4}
  4. Solved Ex.14.4
    Write IUPAC names for the following structures : i. CH3−CH(OH)−C(=O)−CH2−CH3\mathrm{CH_3-CH(OH)-C(=O)-CH_2-CH_3} ii. CH3−CH(NH2)−CH2−COOH\mathrm{CH_3-CH(NH_2)-CH_2-COOH} iii. CH3−CH(OH)−CH2−OH\mathrm{CH_3-CH(OH)-CH_2-OH} iv. CH2=CH−CH=CH2\mathrm{CH_2=CH-CH=CH_2}
  5. Solved Ex.14.5
    Identify the nucleophile and electrophile from NH3\mathrm{NH_3} and C⊕H3\mathrm{\overset{\oplus}{C}H_3}. Also indicate the nucleophilic and electrophilic centres in them. Justify.
  6. Solved Ex.14.6
    Consider the following molecules and answer the questions, CH3−CH2−CH2−Cl\mathrm{CH_3-CH_2-CH_2-Cl}, CH3−CH2−CH2−Br\mathrm{CH_3-CH_2-CH_2-Br}, CH3−CH2−CH2−I\mathrm{CH_3-CH_2-CH_2-I}. (i) What type of inductive effect is expected to operate in these molecules ? (ii) Identify the molecules from these three, having the strongest and the weakest inductive effect.
  7. Solved Ex.14.7
    Which of the CH3−CHCl2\mathrm{CH_3-CHCl_2} and CH3CH2Cl\mathrm{CH_3CH_2Cl} is expected to have stronger -I effect ?
  8. Solved Ex.14.8
    Identify the species that contains a conjugated system of π\pi bonds. Explain your answer. CH2=CH−CH2−CH=CH2\mathrm{CH_2=CH-CH_2-CH=CH_2} (I) CH2=CH−CH=CH−CH3\mathrm{CH_2=CH-CH=CH-CH_3} (II)
  9. Solved Ex.14.9
    Write resonance structures of H−COO⊖\mathrm{H-COO^{\ominus}} and comment on their relative stability.
  10. Solved Ex.14.10
    Identify the species which has resonance stabilization. Justify your answer. (i) CH3−O∙∙−H\mathrm{CH_3-\overset{\bullet\bullet}{O}-H} (ii) CH3−NO2\mathrm{CH_3-NO_2} (iii) buta - 1, 3 - diene
  11. Solved Ex.14.11
    Write three resonance structures for CH3−CH=CH−CHO\mathrm{CH_3-CH=CH-CHO}. Indicate their relative stabilties and explain.

Exercise

53 q

1. Answer the following

Practice · 9
  1. Ex Q.1 (A)
    Write condensed formulae and bond line formulae for the following structures.
  2. Ex Q.1 (B)
    Write dash formulae for the following bond line formulae.
  3. Ex Q.1 (C)
    Write bond line formulae and condensed formulae for the following compounds a. 3-methyloctane b. hept-2-ene c. 2, 2, 4, 4- tetramethylpentane d. octa-1,4-diene e. methoxyethane
  4. Ex Q.1 (D)
    Write the structural formulae for the following names and also write correct IUPAC names for them. a. 5-ethyl-3-methylheptane b. 2,4,5-trimethylthexane c. 2,2,3-trimethylpentan-4-0l
  5. Ex Q.1 (E)
    Identify more favourable resonance structure from the following. Justify. a. CH3−C(=O)−O∙∙H\mathrm{CH_3-C(=O)-\overset{\bullet\bullet}{O}H} ⟷\longleftrightarrow CH3−C(−O⊖)=O⊕H\mathrm{CH_3-C(-O^{\ominus})=\overset{\oplus}{O}H} b. C⊕H2−CH=CH−O⊖\mathrm{\overset{\oplus}{C}H_2-CH=CH-O^{\ominus}} ⟷\longleftrightarrow C⊖H2−CH=CH−O⊕\mathrm{\overset{\ominus}{C}H_2-CH=CH-O^{\oplus}}
  6. Ex Q.1 (F)
    Find out all the functional groups present in the following polyfunctional compounds. a. Dopamine a neurotransmitter that is deficient in Parkinson's disease. b. Thyroxine the principal thyroid hormone. c. Penicillin G a naturally occuring antibiotic
  7. Ex Q.1 (G)
    Find out the most stable species from the following. Justify. a. C∙H3\mathrm{\overset{\bullet}{C}H_3}, CH3−C∙H−CH3\mathrm{CH_3-\overset{\bullet}{C}H-CH_3}, CH3−C∙CH3−CH3\mathrm{CH_3-\underset{CH_3}{\overset{\bullet}{C}}-CH_3} b. C⊖H3\mathrm{\overset{\ominus}{C}H_3}, C⊖H2Br\mathrm{\overset{\ominus}{C}H_2Br}, C⊖Br3\mathrm{\overset{\ominus}{C}Br_3} c. C⊕H3\mathrm{\overset{\oplus}{C}H_3}, C⊕H2Cl\mathrm{\overset{\oplus}{C}H_2Cl}, C⊕Cl3\mathrm{\overset{\oplus}{C}Cl_3}
  8. Ex Q.1 (H)
    Identify the α\alpha - carbons in the following species and give the total number of α\alpha-hydrogen in each.
  9. Ex Q.1 (I)
    Identify primary, secondary, tertiary and quaternary carbon in the following compounds.

2. Match the pairs

Practice · 1
  1. Ex Q.2
    Match the pairs
    Column 'A'Column 'B'
    i. Inductive effecta. delocalisation of π\pi electrons
    ii. Hyperconjugationb. displacement of π\pi electrons
    iii. Resonance effectc. delocalisation of σ\sigma electrons
    d. displacement of σ\sigma electrons

3. Homologous series

Practice · 1
  1. Ex Q.3
    What is meant by homologous series ? Write the first four members of homologous series that begins with A. CH3CHO\mathrm{CH_3CHO} B. H−C≡C−H\mathrm{H-C \equiv C-H} Also write down their general molecular formula.

4. Write IUPAC names of the following

Practice · 6
  1. Write IUPAC names of the following
    Ex Q.4 (A)
    A.
  2. Ex Q.4 (B)
    B.
  3. Ex Q.4 (C)
    C.
  4. Ex Q.4 (D)
    D.
  5. Ex Q.4 (E)
    E.
  6. Ex Q.4 (F)
    F.

5. Find out the type of isomerism

Practice · 4
  1. Find out the type of isomerism exhibited by the following pairs.
    Ex Q.5 (A)
    A. CH3−CH2−NH−CH2−CH3\mathrm{CH_3-CH_2-NH-CH_2-CH_3} and CH3−NH−CH2−CH2−CH3\mathrm{CH_3-NH-CH_2-CH_2-CH_3}
  2. Ex Q.5 (B)
    B. CH3−CHOH−CH2−CH3\mathrm{CH_3-\underset{OH}{CH}-CH_2-CH_3} and CH3−CH2−O−CH2−CH3\mathrm{CH_3-CH_2-O-CH_2-CH_3}
  3. Ex Q.5 (C)
    C. CH3−CH2−N⊕(=O)−O⊖\mathrm{CH_3-CH_2-\overset{\oplus}{N}(=O)-O^{\ominus}} and CH3−CH=N⊕(−OH)−O⊖\mathrm{CH_3-CH=\overset{\oplus}{N}(-OH)-O^{\ominus}}
  4. Ex Q.5 (D)
    D.

6. Draw resonance srtuctures of the following

Practice · 4
  1. Draw resonance srtuctures of the following :
    Ex Q.6 (A)
    A. Phenol
  2. Ex Q.6 (B)
    B. Benzaldehyde
  3. Ex Q.6 (C)
    C. Buta-1,3-diene
  4. Ex Q.6 (D)
    D. Acetate ion

7. Distinguish

Practice · 4
  1. Distinguish :
    Ex Q.7 (A)
    A. Inductive effect and resonance effect
  2. Ex Q.7 (B)
    B. Electrophile and nucleophile
  3. Ex Q.7 (C)
    C. Carbocation and carbanion
  4. Ex Q.7 (D)
    D. Homolysis and heterolysis

8. Write true or false

Practice · 4
  1. Write true or false. Correct the false stament
    Ex Q.8 (A)
    A. Homolytic fission involves unsymmetrical breaking of a covalent bond.
  2. Ex Q.8 (B)
    B. Heterolytic fission results in the formation of free radicals.
  3. Ex Q.8 (C)
    C. Free radicals are negatively charged species
  4. Ex Q.8 (D)
    D. Aniline is heterocyclic compound.

9. Phytane

Practice · 1
  1. Ex Q.9
    Phytane is naturally occuring alkane produced by the alga spirogyra and is a constituent of petroleum. The IUPAC name for phytane is 2,6,10,14-tetramethylhexadecane. Write zig-zag formula for phytane. How many primary, secondary, tertiary and quaternary carbons are present in this molecule.

10. Observe the following structures

Practice · 3
  1. Observe the following structures and answer the questions given below. (i) CH3−CH2−CH2−CHO\mathrm{CH_3-CH_2-CH_2-CHO} (ii) CH3−CHCH3−CHO\mathrm{CH_3-\underset{CH_3}{CH}-CHO}
    Ex Q.10 (a)
    a. What is the relation between (i) and (ii) ?
  2. Ex Q.10 (b)
    b. Write IUPAC name of (ii).
  3. Ex Q.10 (c)
    c. Draw the functional group isomer of (i).

11. Observe the following

Practice · 3
  1. Observe the following and answer the questions given below CH3−CH3→U. V. lightC∙H3+C∙H3\mathrm{CH_3-CH_3} \xrightarrow{\text{U. V. light}} \mathrm{\overset{\bullet}{C}H_3 + \overset{\bullet}{C}H_3}
    Ex Q.11 (a)
    a. Name the reactive intermediae produced
  2. Ex Q.11 (b)
    b. Indicate the movement of electrons by suitable arrow to produce this intermediate
  3. Ex Q.11 (c)
    c. Comment on stability of this intermediate produced.

12. Electronic displacement notation

Practice · 2
  1. An electronic displacement in a covalent bond is represented by following noation. Cδ⊕H3→Cδ⊕H2→Cδ⊖l\mathrm{\overset{\delta\oplus}{C}H_3 \rightarrow \overset{\delta\oplus}{C}H_2 \rightarrow \overset{\delta\ominus}{C}l}
    Ex Q.12 (A)
    A. Identify the effect
  2. Ex Q.12 (B)
    B. Is the displacement of electrons in a covalent bond temporary or permanent.

13. No-bond resonance structures

Practice · 1
  1. Ex Q.13
    Draw all the no-bond resonance structures of isopropyl carbocation.

14. tert-Butylbromide

Practice · 3
  1. A covalent bond in tert-butylbromide breaks in a suitable polat solvent to give ions.
    Ex Q.14 (A)
    A. Name the anion produced by this breaking of a covalent bond.
  2. Ex Q.14 (B)
    B. Indicate the type of bond breaking in this case
  3. Ex Q.14 (C)
    C. Comment on geometry of the cation formed by such bond cleavage.

15. Choose correct options

Practice · 7
  1. Ex Q.15 (A)
    Choose correct option. Which of the following statements are true with respect to electronic displacement in covalent bond ? a. Inductive effect operates through π\pi bond b. Resonance effect operates through σ\sigma bond c. Inductive effect operates through σ\sigma bond d. Resonance effect operates through π\pi bond
    1. A.
      a. and b
    2. B.
      a and c
    3. C.
      c and d
    4. D.
      b and c
  2. Ex Q.15 (B)
    Choose correct option. Hyperconjugation involves overlap of ..... orbitals
    1. A.
      σ−σ\sigma - \sigma
    2. B.
      σ−p\sigma - p
    3. C.
      p−pp - p
    4. D.
      π−π\pi - \pi
  3. Ex Q.15 (C)
    Choose correct option. Which type of isomerism is possible in CH3CHCHCH3\mathrm{CH_3CHCHCH_3}?
    1. A.
      Position
    2. B.
      Chain
    3. C.
      Geometrical
    4. D.
      Tautomerism
  4. Ex Q.15 (D)
    Choose correct option. The correct IUPAC name of the compound shown is .....
    1. A.
      hept-3-ene
    2. B.
      2-ethylpent-2-ene
    3. C.
      hex-3-ene
    4. D.
      3-methylhex-3-ene
  5. Ex Q.15 (E)
    Choose correct option. The geometry of a carbocation is ......
    1. A.
      linear
    2. B.
      planar
    3. C.
      tetrahedral
    4. D.
      octahedral
  6. Ex Q.15 (F)
    Choose correct option. The homologous series of alcohols has general molecular formula .........
    1. A.
      CnH2n+1OH\mathrm{C_nH_{2n+1}OH}
    2. B.
      CnH2n+2OH\mathrm{C_nH_{2n+2}OH}
    3. C.
      CnH2n−2OH\mathrm{C_nH_{2n-2}OH}
    4. D.
      CnH2nOH\mathrm{C_nH_{2n}OH}
  7. Ex Q.15 (G)
    Choose correct option. The delocaalization of electrons due to overlap between p-orbital and sigma bond is called
    1. A.
      Inductive effect
    2. B.
      Electronic effect
    3. C.
      Hyperconjugation
    4. D.
      Resonance