Thu January 03, 2013 By:

how to identify the electrophile and nucleophile in cross aldol process ? also please explain aldol and cross aldol condensation in detail.

Expert Reply
Fri January 04, 2013
Alkyl groups are electron donating (whereas hydrogen atoms aren't). A ketone has 2 alkyl groups attached to the carbonyl carbon, but an aldehyde has only 1 alkyl group attached to its carbonyl carbon. This gives the aldehyde carbon more positive charge character, which makes it a better electrophile than the ketone. Another factor is less stearic hindrence for carbonyl carbon of aldehyde as compare to ketones.

An aldol condensation is an organic reaction in which an enol or an enolate ion reacts with a carbonyl compound to form a ?-hydroxyaldehyde or ?-hydroxyketone, followed by adehydration to give a conjugated enone.

Aldol condensations are important in organic synthesis, providing a good way to form carbon–carbon bonds.

The reactions between a ketone and a carbonyl compound lacking an alpha-Hydrogen is known as Cross Aldol condensation or Claisen-Schmidt condensation.
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