Short Answer TypeAccount for the following:
(i) CH3CHO is more reactive than CH3 COCH3 towards reaction with HCN.
(ii) The carboxylic acid is a stronger acid than phenol.
(i) CH3COCH3 is sterically hindered than CH3CHO due to the presence of alkyl group on both sides of the carbonyl carbon, making them less reactive towards nucleophilic attack because both methyl groups have electron releasing tendency due to -I effect. These alkyl groups make ketone less reactive by donating an electron to a carbonyl group. Therefore, acetaldehyde is more reactive towards reaction with HCN.
(ii) Carboxylic acids are acidic due to resonance stabilisation of carboxylate anion and in phenols, the acidic character is present due to resonance stabilisation of phenoxide anion. Carboxylic acids are more acidic than phenols because the negative charge in carboxylate anion is more spread out compared to the phenoxide ion, as there are two electronegative O-atoms in carboxylate anion compared to one in phenoxide ion. In the resonance structures of carboxylate anion, the negative charge is present on the O-atoms, while in the resonance of phenoxide ion, a negative charge is also present on the electropositive carbon atom, which leads to less stability of phenoxide ion than carboxylate anion.
Write the chemical equations to illustrate the following name reactions:
(i) Wolff-Kishner reduction
(ii) Aldol condensation
(iii) Cannizzaro reaction
Long Answer TypeHow will you bring about the following conversions?
(i) Propanone to propane
(ii) Benzoyl chloride to benzaldehyde
(iii) Ethanal to but-2-enal
Short Answer TypeIllustrate the following name reaction giving suitable example in each case:
(i) Clemmensen reduction
(ii) Hell-Volhard-Zelinsky reaction
Give simple tests to distinguish between the following pairs of compounds.
(i) Pentan-2-one and Pentan-3-one
(ii) Benzaldehyde and Acetophenone
(iii) Phenol and Benzoic acid
Illustrate the following reactions giving a suitable example for each.
(i) Cross aldol condensation
(ii) Decarboxylation
Give simple tests to distinguish between the following pairs of compounds
(i) Pentan-2-one and Pentan-3-one
(ii) Benzaldehyde and Acetophenone
(iii) Phenol and Benzoic acid
Explain the following giving one example for each:
(i) Reimer-Tiemann reaction.
(ii) Friedel Craft’s acetylation of anisole.
Long Answer TypeGive chemical tests to distinguish between
(i) Propanal and propanone,
(ii) Benzaldehyde and acetophenone.
(b) How would you obtain
(i) But-2-enal from ethanal,
(ii) Butanoic acid from butanol,
(iii) Benzoic acid from ethylbenzene?
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