Beta hydroxyaldehyde Question

[jdpaul14]

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Ok, so the question I have is:

Q: The base-catalyzed condensation of two acetaldehydes is:

A: B hydroxyaldehyde


...why wouldn't it be Alpha Hydroxyaldehyde?

Is it because you name the product starting at the carbonyl carbon?

Thanks

 

[GiTsticker]

It's because the -OH group is attached to the beta carbon (the second carbon over from the carbonyl carbon).

 

[nze82]

Ok, so the question I have is:

Q: The base-catalyzed condensation of two acetaldehydes is:

A: B hydroxyaldehyde


...why wouldn't it be Alpha Hydroxyaldehyde?

Is it because you name the product starting at the carbonyl carbon?

Nope! It's because the way the reaction proceeds (Look Below). Due to this mechanism, the -OH group will always sit in the Betha position relative to the carbonyl group.

Thanks