Is the Alpha Carbon on Ketone or Aldehyde more Nucleophilic?

[drillers]

So I know that for the most part:

Aldehydes are more reactive. They are more electrophilic due to induction and sterics.

Aldehydes are more acidic pretty much for the same reasons. In ketones the carbon groups are e- donating and they destabilize the conjugate base making ketone's conj base stronger and more basic

Since the Ketone is more basic (again I know it's not true that better base = better nucleophile) because of the e- donation of the carbon groups, isn't the alpha carbon of a ketone more nucleophilic than the alpha carbon on the aldehyde?

My gut tells me the Ketone's alpha carbon is more Nucleophilic than the aldehyde... what do you think?

---

Members don't see this ad.

 

[Schenker]

My gut tells me the Ketone's alpha carbon is more Nucleophilic than the aldehyde... what do you think?

Hmm, could be! Though, an aldehyde's corresponding ketone will always be more sterically hindered. Whether or not that reduces the nucleophilicity of the ketone below that of the aldehyde would depend on the R group. I don't know of a way to reliably predict which enolate will be more nucleophilic.

When predicting reactions where we have both ketone and aldehyde enolates, there is a more important factor that should be considered, which you mentioned: aldehydes are more electrophilic than ketones. That is, in a mixed aldol reaction, nucleophilic attack of the ketone enolate on the aldehyde is favored over nucleophilic attack of the aldehyde enolate on the ketone.