Formation of imines from primary amines and ketones

by James

Description: Reaction of a primary amine with an aldehyde or ketone results in an imine. The reaction results in the formation of one equivalent of water.
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{ 7 comments… read them below or add one }


why primary amines under diazonium reaction



If you use secondary amines you can’t form the triple bond.



For the first step, why does e proton source attack the carbonyl oxygen instead of the more basic amine in the reaction mixture? Is it because of resonance in e protonated carbonyl?

Do we add e acid and e amine at the same time?

Can the acid be a weak acid as strong acidic conditions may protonate e amine and render it non nucleophilic?

Thanks :)


Rich Aversa

I was wondering this as well.



The amine is more basic, this is true! Acid can attack the amine, but it doesn’t go anywhere (the amine and protonated amine are in equilibrium). It’s a dead end, in other words.

You just need a little bit of protonated carbonyl to get the reaction going.

It’s important that the solution not be too acidic, since if all the amine is protonated (irreversibly) then there is no nucleophile that would be able to attack the carbonyl.



My textbook shows this reaction in water. Without acid, is the carbinolamine a stable form?



Imine formation IN water – or is it imine hydrolysis?

Imine formation in water is not going to be successful unless you are forming a particularly stable imine (such as a cyclic 5 or 6 membered imine) and even then you’ll probably get a lot of the carbinolamine.


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