The aldol condensation self-reaction of acetaldehyde yields which aldol product?

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Multiple Choice

The aldol condensation self-reaction of acetaldehyde yields which aldol product?

In an aldol reaction, one acetaldehyde molecule forms an enolate and adds to the carbonyl carbon of another acetaldehyde molecule, creating a new C–C bond and a beta-hydroxy aldehyde after workup. For two acetaldehyde molecules, this gives CH3-CH(OH)-CH2-CHO, which is named 3-hydroxybutanal. This is the direct aldol addition product of the self-condensation. If the mixture is heated under basic conditions, dehydration can follow to give crotonaldehyde (an α,β-unsaturated aldehyde), but the immediate aldol product is the beta-hydroxy aldehyde. The other options don’t represent the aldol addition product: crotonaldehyde would be the dehydration product, ethanol is a reduced product, and propanal is not the result of this self-aldol addition.

In an aldol reaction, one acetaldehyde molecule forms an enolate and adds to the carbonyl carbon of another acetaldehyde molecule, creating a new C–C bond and a beta-hydroxy aldehyde after workup. For two acetaldehyde molecules, this gives CH3-CH(OH)-CH2-CHO, which is named 3-hydroxybutanal. This is the direct aldol addition product of the self-condensation. If the mixture is heated under basic conditions, dehydration can follow to give crotonaldehyde (an α,β-unsaturated aldehyde), but the immediate aldol product is the beta-hydroxy aldehyde. The other options don’t represent the aldol addition product: crotonaldehyde would be the dehydration product, ethanol is a reduced product, and propanal is not the result of this self-aldol addition.

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