Aldol vs. hydration

[crazyasian]

So according to my Ochem book if an aldehyde is mixed with H20 and a base or acid it can undergo hydrolysis and a diol is formed. I'm doing practice problems and whenever I see an aldehyde with H2O and a base/acid it undergoes aldol condensation. The reaction uses the exact same reagents, but the mechanism is different. Is there something i'm missing? I'm having problems distinguishing when its an aldol condensation and when its a hydration.

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[Isoprop]

Are you talking about a gem-diol? Yes, any carbonyl + water can make a gem-diol. Generally, the gem-diol isn't very stable so the equilibrium of this reaction lies to the carbonyl side. It's generally not an important reaction in MCAT O-Chem.

A ketone/aldehyde will generally undergo an aldol reaction in the presence of a base like LDA (to form the enolate). This reaction IS important on the MCAT, so this is the one worth spending time on.

So in the end, both reactions will happen. What's more important for the MCAT is the aldol reaction. I hope that answers your question.

 

[crazyasian]

ok that helps alot. Thank you. I'll just think aldol from now on.