ALDOL CONDENSATION

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ALDOL CONDENSATION

• PRESENTED BY MR K V NANDA KUMAR
• ASSOCIATE PROFESSOR
• KRISHNA TEJA PHARMACY COLLEGE, TIRUPATHI-517506

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Aldol Condensation

• The aldol condensation reaction is an organic
  reaction introduced by Charles Wurtz, who first
  prepared the ß-hydroxy aldehyde from acetaldehdye
  in 1872.
• Two molecules of an aldehyde or a ketone undergo
  a condensation reaction in the presence of a base
  to yield ß hydroxyaldehyde or ß
  hydroxyketone.

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Aldols

• An aldol or aldol adduct (from "aldehyde
  alcohol") is a hydroxy ketone or aldehyde, and is
  the product of aldol addition (as opposed to
  aldol condensation, which produces an
  a,ß-unsaturated carbonyl moiety).
• When used alone, the term "aldol" may also refer
  specifically to the compound 3-hydroxybutanal

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General Aldol Condensation Reaction

• Aldol Condensation can be defined as an organic
  reaction in which enolate ion reacts with a
  carbonyl compound to form ß-hydroxy ketone or
  ß-hydroxy aldehyde, followed by dehydration to
  give a conjugated enone.
• Aldol Condensation plays a vital role in organic
  synthesis, creating a path to form carbon-carbon
  bonds.

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Mechanism of aldol condensation

• Step 1
• In reverse order, the hydroxide ion deprotonates
  the aldehyde.

Enolate ion
Water
Aldehyde
Hydroxide ion
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Mechanism of aldol condensation

• Step 2
• Here Enolate ion 1 adds to the unreacted
  aldehyde.
• .

Unreacted Aldehyde
Alkoxide ion
Enolate ion
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Mechanism of aldol condensation

• Step 3
• Alkoxide ion 2 is protonated by water.

Aldol
Hydroxide ion
Alkoxide ion
Water
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Mechanism of aldol condensation

• Step 4
• A small amount of aldol is converted into enolate
  ion (4) by hydroxide ion.

Enolate ion
Water
Hydroxide ion
Aldol
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Mechanism of aldol condensation

• Step 5
• Here Enolate Ion(4) loses a hydroxide ion.

Step 1 to step 3 illustrates the aldol reaction.
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Crossed aldol condensation

• The condensation reaction between two different
  molecules of an aldehyde or ketone in a protic
  solvent such as water or alcohol constitutes the
  crossed aldol reaction.
• When condensation is between two different
  carbonyl compounds, it is called crossed aldol
  condensation. 

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Questions

1. What is aldol condensation?
2. Give one example for aldol condensation reaction.
3. Explain the mechanism of aldol condensation.

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