The Aldol condensation reaction requires the loss of a molecule of water. Perfor
ID: 936588 • Letter: T
Question
The Aldol condensation reaction requires the loss of a molecule of water. Performing the reaction in water should disfavor this reversible dehydration reaction from occurring. Based on your observations during the laboratory provide a reasonable explanation for why the condensation product occurs at all? NOTE: Heat accelerates the reaction reaching equilibrium but DOES NOT directly favor the Aldol Condensation product.
The Reaction was :
Reaction Conditions 1:
In a 50-mL round-bottomed flask, with a spin bar, add 10mL of H2O solution which contains 1.0 mmol of 2-acetylpyridine. Stir the mixture vigorously.
Place 1.0 mmol of 4-nitrobenzaldehyde in a separate vial and dissolve using a minimum amount of warm MeOH. While still warm, add the solution of 4-nitrobenzaldehyde to the stirring mixture in the round-bottomed flask.
To this mixture add 0.25 mmol of Na2CO3 dissolved in 5 mL of H2O.
After 1 hr of vigorous stirring, collect the solid product using vacuum filtration and wash with H2O (3 x 10mL) and a minimal amount of cold MeOH.
Allow the product to dry on the vacuum, determine the yield, melting point and record the IR spectra of your product.
Reaction Conditions 2:
In a 50-mL round-bottomed flask, with a spin bar, add 10mL of H2O solution which contains 1.0 mmol of 2-acetylpyridine. Stir the mixture vigorously.
Place 1.0 mmol of 4-nitrobenzaldehyde in a separate vial and dissolve using a minimum amount of warm MeOH. While still warm, add the solution of 4-nitrobenzaldehyde to the stirring mixture in the round-bottomed flask.
To this mixture add 0.25 mmol of Na2CO3 dissolved in 5 mL of H2O.
Attach a water-cooled reflux condenser and heat the reaction to reflux using an oil bath or a heating mantle.
After 1 hr of vigorous stirring at reflux, cool the reaction using an ice-water bath, collect the solid product using vacuum filtration. Wash the solid with H2O (3 x 10mL) and a minimal amount of cold MeOH.
Allow the product to dry on the vacuum, determine the yield, melting point and record the IR spectra of your product.
Explanation / Answer
heat fovors the formation of the aldolic condensation product because the transition state for the dehydratation( an E2 mechanism) is highly energetic. (-OH is not a good leaving group)
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