Master Organic Chemistry Reaction Guide

Formation of imines from primary amines and ketones

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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16 thoughts on “Formation of imines from primary amines and ketones

  1. 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 :)

    1. 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.

      1. Why would protonation of the amine be irreversible?

        Very well written and illustrated articles – many thanks.

        JT

    1. 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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