Explain aldol condensation reactions of ethanal & propanone.

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Solution

When an aldehyde (or a ketone) having alpha hydrogen atom is treated with dilute base NaOH, KOH or sodium carbonate, two molecules of aldehyde ( or ketone) add together to form $β$ hydroxy aldehyde (aldol) or $β$ hydroxy ketone (ketol). New $C - C$ bond is formed in this reaction.
When aldol or ketol is heated in presence of an acid, a molecule of water is lost and $α - β$ unsaturated aldehyde or $α - β$ unsaturated ketone is formed.

Aldol condensation of ethanal:
$2 C H_{3} - C H O dil NaOH - ----- \to C H_{3} - C H O H - C H_{2} - C H O H^{+} - - \to Δ C H_{3} - C H = C H - C H O + H_{2} O$
Aldol condensation of propanone:
$2 (C H_{3})_{2} C O dil NaOH - ----- \to (C H_{3})_{2} C - O H - C H_{2} - C O - C H_{3} H^{+} - - \to Δ (C H_{3})_{2} C = C H - C O - C H_{3} + H_{2} O$

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Similar questions

Q. Ethanal

(C H_{3} C H O)

undergoes aldol condensation reaction. Give reason.

Which of the following compounds would undergo aldol condensation, which the Cannizzaro reaction and which neither ? Write the structures of the expected products of aldol condensation or Cannizzaro reaction ?

Methanal

2-methyl pentanal

Benzaldehyde

Benzophenone

Cyclohexanone

l - phenyl propanone

Phenyl acetaldehyde

Butan - 1 - ol

2, 2 - dimethyl butanal

Q. Which of the given aldehydes will not give aldol condensation reactions?

(1) Propanal (2) Ethanal (3)

2.2

-dimethylpropane (4)

2, 2

-dimethyl butanal (5) Benzaldehyde

Q. Write the structures and

I U P A C

names of the cross aldol condensation products only of ethanal and propanal.

Q. Write te structural formula and names of all four possible aldol condensation products from ethanal and propanal

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