Aldol Condensation!

[sap1622]

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Alright so I;m still having trouble figuring this one out. I know it involves 2 aldehyde in the reaction. I thought an alpha H was ripped off by a base and it nucleophillically attacked the other aldehyde. I was looking at one of those MCAT Organic Chemistry study guides and I don't see how the reaction works. Can someone explain?!

It's attached (dunno how to put the pic here)

 

[invictusx]

Alright so I;m still having trouble figuring this one out. I know it involves 2 aldehyde in the reaction. I thought an alpha H was ripped off by a base and it nucleophillically attacked the other aldehyde. I was looking at one of those MCAT Organic Chemistry study guides and I don't see how the reaction works. Can someone explain?!

It's attached (dunno how to put the pic here)

This reaction is correct because in aldehydes, you don't really have any alpha hydrogens. It depends on the substituents. Aldol condensations usually produce alpha-beta unsaturated bonds.. In this case, it's not shown. But no, you're right. It does nucleophilically attack--that first molecule is a resonance structure of what you thought originally. The reason why there's no negative charge is probably because you're in MILD base. But that's just my two-cents. I'm not 100% sure but there are many ways of doing this mechanism

 

[RCLEE]

When the question involves the aldehyde and ketone always think enolation. The keto and enol form exist in solution which is not possible to form an enol in a acidic environmet, but in a basic environment, the enol form exist. Normally, the there are higher [] of the keto form since they are more stable. In the picture, the attacking reactant with the alkene and alcohol = enol attacked the electron poor carbonyl carbon. This reaction is correct! Key words: enol, keto, enolation, tautomerization.

 

[sap1622]

uhh Idk bout the last post but... for the test will they tell us in the question that its gonna be an Aldol reaction or like a Michael addition? I really hope so lol.

 

[invictusx]

uhh Idk bout the last post but... for the test will they tell us in the question that its gonna be an Aldol reaction or like a Michael addition? I really hope so lol.

Nope. They give you reactants and you find the product. Answers are obvious, though. But choose carefully. I don't think Michael's addition is tested often but it is an essential reaction

 

[adianadiadi]

yes you are right. The enol is formed by removing one alpha hydrogen by base.