Chemistry · Textbook solutions

Aldehydes, Ketones and Carboxylic Acids

Every solved example, exercise, and miscellaneous question — in the order the textbook teaches them. · 29 questions

12. Aldehydes, Ketones and Carboxylic Acids — worked examples

1 q

Solved Examples

Worked · 1
  1. Solved Ex.12.1
    Alcohols (R−OH)(\mathrm{R-OH}), phenols (Ar−OH)(\mathrm{Ar-OH}) and carboxylic acids (R−COOH)(\mathrm{R-COOH}) can undergo ionization of O−H\mathrm{O-H} bond to give away proton H⊕\mathrm{H^{\oplus}}; yet they have different pKa\mathrm{p}K_\mathrm{a} values, which are 16, 10 and 4.5 respectively. Explain

Exercises

28 q

1. Choose the most correct option.

Practice · 6
  1. Choose the most correct option.
    Ex Q.1 (i)
    In the following resonating structures A and B, the number of unshared electrons in valence shell present on oxygen respectively are (A) >C=O\mathrm{{>}C{=}O} ⟷\longleftrightarrow (B) >C⊕−O⊖\mathrm{{>}C^{\oplus}-O^{\ominus}}
    1. A.
      2, 4
    2. B.
      2, 6
    3. C.
      4, 6
    4. D.
      6, 4
  2. Ex Q.1 (ii)
    In the Wolf -Kishner reduction, alkyl aryl ketones are reduced to alkyl benzenes. During this change, ketones are first converted into
    1. A.
      acids
    2. B.
      alcohols
    3. C.
      hydrazones
    4. D.
      alkenes
  3. Ex Q.1 (iii)
    Aldol condensation is
    1. A.
      electrophilic substitution reaction
    2. B.
      nucleophilic substitution reaction
    3. C.
      elimination reaction
    4. D.
      addition - elimination reaction
  4. Ex Q.1 (iv)
    Which one of the following has lowest acidity ?
    1. A.
      3−NO2−C6H4−COOH\mathrm{3-NO_2-C_6H_4-COOH}
    2. B.
      2−Cl−C6H4−COOH\mathrm{2-Cl-C_6H_4-COOH}
    3. C.
      C6H5−COOH\mathrm{C_6H_5-COOH}
    4. D.
      4−OCH3−C6H4−COOH\mathrm{4-OCH_3-C_6H_4-COOH}
  5. Ex Q.1 (v)
    Diborane reduces
    1. A.
      ester group
    2. B.
      nitro group
    3. C.
      halo group
    4. D.
      acid group
  6. Ex Q.1 (vi)
    Benzaldehyde does NOT show positive test with
    1. A.
      Schiff reagent
    2. B.
      Tollens' ragent
    3. C.
      Sodium bisulphite solution
    4. D.
      Fehling solution

2. Answer the following in one sentence

Practice · 10
  1. Answer the following in one sentence
    Ex Q.2 (i)
    What are aromatic ketones?
  2. Ex Q.2 (ii)
    Is phenyl acetic acid an aromatic carboxylic acid ?
  3. Ex Q.2 (iii)
    Write reaction showing conversion of ethanenitrile into ethanol.
  4. Ex Q.2 (iv)
    Predict the product of the following reaction: CH3−CH2−COOCH3→ii. H3O⊕i. AlH(i-Bu)2?\mathrm{CH_3-CH_2-COOCH_3} \xrightarrow[\text{ii. } \mathrm{H_3O^{\oplus}}]{\text{i. } \mathrm{AlH(i\text{-}Bu)_2}} ?
  5. Ex Q.2 (v)
    Name the product obtained by reacting toluene with carbon monoxide and hydrogen chloride in presence of anhydrous aluminium chloride.
  6. Ex Q.2 (vi)
    Write reaction showing conversion of Benzonitrile into benzoic acid.
  7. Ex Q.2 (vii)
    Name the product obtained by the oxidation of 1,2,3,4-tetrahydronaphthalene with acidified potassium permanganate .
  8. Ex Q.2 (viii)
    What is formalin ?
  9. Ex Q.2 (ix)
    Arrange the following compounds in the increasing order of their boiling points : Formaldehyde, ethane, methyl alcohol.
  10. Ex Q.2 (x)
    Acetic acid is prepared from methyl magnesium bromide and dry ice in presence of dry ether. Name the compound which serves not only reagent but also as cooling agent in the reaction.

3. Answer in brief.

Practice · 7
  1. Answer in brief.
    Ex Q.3 (i)
    Observe the following equation of reaction of Tollens' reagent with aldehyde. How do we know that a redox reaction has taken place. Explain. R−CHO+2 Ag(NH3)2++OH−→ΔR−COO−+2 Ag↓+4 NH3+2 H2O\mathrm{R-CHO} + 2\ \mathrm{Ag(NH_3)_2^{+}} + \mathrm{OH^{-}} \xrightarrow{\Delta} \mathrm{R-COO^{-}} + 2\ \mathrm{Ag}\downarrow + 4\ \mathrm{NH_3} + 2\ \mathrm{H_2O}
  2. Ex Q.3 (ii)
    Formic acid is stronger than acetic acid. Explain.
  3. Ex Q.3 (iii)
    What is the action of hydrazine on cyclopentanone in presence of ---. KOH in ethylene glycol ?
  4. Ex Q.3 (iv)
    Write reaction showing conversion of Acetaldehyde into acetaldehyde dimethyl acetal.
  5. Ex Q.3 (v)
    Aldehydes are more reactive toward nucleophilic addition reactions than ketones. Explain.
  6. Ex Q.3 (vi)
    Write reaction showing the action of the following reagent on propanenitrile – a. Dilute NaOH b. Dilute HCl ?
  7. Ex Q.3 (vi-b)
    Arrange the following carboxylic acids with increasing order of their acidic strength and justify your answer.

4. Answer the following

Practice · 5
  1. Answer the following
    Ex Q.4 (i)
    Write a note on – a. Cannizaro reaction b. Stephen reaction.
  2. Ex Q.4 (ii)
    What is the action of the following reagents on toluene ? a. Alkaline KMnO4\mathrm{KMnO_4} , dil. HCl\mathrm{HCl} and heat b. CrO2Cl2\mathrm{CrO_2Cl_2} in CS2\mathrm{CS_2} c. Acetyl chloride in presence of anhydrous AlCl3\mathrm{AlCl_3}.
  3. Ex Q.4 (iii)
    Write the IUPAC names of the following structures :
  4. Ex Q.4 (iv)
    Write reaction showing conversion of p- bromoisopropyl benzene into p-Isopropyl benzoic acid ( 3 steps).
  5. Ex Q.4 (v)
    Write reaction showing aldol condensation of cyclohexanone.