Aldol Condensation of propanal


Structure of Propanal :

propanal structure, propionaldehyde

General Aldol reaction of Propanal :

When the two molecules of propanal (propionaldehyde) is react with sodium hydroxide (any base) it will form Aldol Product. After the process, while heating the Aldol product of propanal, water (H20) is eliminated. The product that we got after heating is called Aldol Condensation of Propanal.

The General Reaction for Aldol Condensation product is given below ;

aldol condensation of propanal

Reaction mechanism of Aldol condensation of Propanal :

Here I have listed the complete reaction mechanism of Aldol Condensation of Propanal in step by step ;

  1. Formation of Carbanion
  2. Attack of Nucleophile
  3. Acid Workup
  4. Dehydration

Step 1 : (Formation of Carbanion)

In this step, one molecule of propanal is react with the hydroxyl ion of the base. α – Hydrogen is abstracted by the base resulting in a formation of carbanion intermediate.

aldol condensation 0f propanal, formation of carbanion

Step 2 : (Attack of Nucleophile)

Carbanion that formed in the previous step is act as Nucleophile and it attack the another propanal molecule resulting in formation of enolate ion

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aldol condensation of propanal,  reaction mechanism

Step 3 : (Acid Workup)

When we add acid to the Enolate ion, it is converted into Hydroxy function group. This is known to be aldol product of propanal.

aldol condensation of propanal, aldol addition product, reaction mechanism

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Step 4 : Dehydration

the product formed in the previous step is heated in high temperature to get condensed product. This product is known to be Aldol condensation of propanal, resulting molecule is 2-methylpent-2-enal

aldol condensation of propanal, final product of aldol condensation of propanal

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You can Download the Reaction Mechanism of Aldol Condensation of Propanal, By clicking the below  “DOWNLOAD PDF ” button 


Conclusion :

  • The parent molecule is Propanal
  • Reagent used is Base (Any Base)
  • It is a step wise reaction
  • It is an Nucleophilic Addition reaction
  • α – Hydrogen is abstracted by the base to form Carbanion Intermediate
  • This Carbanion is act as a Nucleophile
  • Then, Formed nucleophile is attack the electrophilic centre of another propanal molecule
  • Resulting in the formation of Aldol Addition product
  • Then Aldol addition product undergoes H2O elimination by heating to form dehydrated product
  • That resulting product is known as Aldol Condensation product



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