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- Mar 12, 2005
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Hi Dr. Romano,
in Destroyer you indicate that the reaction of a ketone with an aldehyde basic conditions and heat would result in the aldol product that has an alkene. But if there is no heat the hydroxyl group is retained. However, I saw a question in Topscore in which they reacted benzaldehyde with propanone under NaOH/H3O and the product yields the aldol that has an alkene in it. Shouldn't we not see the alkene since we did not use heat??
Answer
Usually heat is needed to allow for the dehydration. However, if near a benzene ring, no heat is needed. Why ? The reaction goes forward because the product is CONJUGATED. This is the driving force. The beta-hydroxycarbonyl compound moves forward..... to dehydration. A problem like this is shown in DESTROYER as well. The Topscore problem is correctly done.
in Destroyer you indicate that the reaction of a ketone with an aldehyde basic conditions and heat would result in the aldol product that has an alkene. But if there is no heat the hydroxyl group is retained. However, I saw a question in Topscore in which they reacted benzaldehyde with propanone under NaOH/H3O and the product yields the aldol that has an alkene in it. Shouldn't we not see the alkene since we did not use heat??
Answer
Usually heat is needed to allow for the dehydration. However, if near a benzene ring, no heat is needed. Why ? The reaction goes forward because the product is CONJUGATED. This is the driving force. The beta-hydroxycarbonyl compound moves forward..... to dehydration. A problem like this is shown in DESTROYER as well. The Topscore problem is correctly done.
