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Question : 30
Total: 30
(a) Although phenoxide ion has more number of resonating structures than carboxylate ion, Carboxylic acid is a stronger acid than phenol. Give two reasons.
(b) How will you bring about the following conversions?
(i) Propanone to propane
(ii) Benzoyl chloride to benzaldehyde
(iii) Ethanal to but-2-enal
OR
(a) Complete the following reactions:
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol
(b) How will you bring about the following conversions?
(i) Propanone to propane
(ii) Benzoyl chloride to benzaldehyde
(iii) Ethanal to but-2-enal
OR
(a) Complete the following reactions:
(b) Give simple chemical tests to distinguish between the following pairs of compounds:
(i) Ethanal and Propanal
(ii) Benzoic acid and Phenol
Solution:
(a) Resonating structure of phenoxide:
(b) (i) Propanone to propane (Wolff-Kishner Reduction)
(iii)
C H 3 −
− C H 2 − C H O
C H 3 − C H = C H − C H O
OR
(a) (i)
(ii)
B r − C H 2 − C O O H
(ii) In carboxylate ion, negative charge delocalized on both oxygen atom which is highly electronegative and contributed more in stability of resonating structure of carboxylate ion.
(ii) Benzoic acid to phenol:
(b) (i) Propanone to propane (Wolff-Kishner Reduction)
(iii)
OR
(a) (i)
(ii)
(i) In phenoxide resonating structure only I & IV carry the negative charge. So, it is negligibly contributed in the stability of phenoxide ion. Here, negative charge is present on one oxygen atom.
(ii) In carboxylate ion, negative charge delocalized on both oxygen atom which is highly electronegative and contributed more in stability of resonating structure of carboxylate ion.
(ii) Benzoic acid to phenol:
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