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Lizzy Due?as Gaytan

How do you convert secondary amine into primary amine?

Alan Brown  Follow

I usually skip these types of questions on Quora since they sound like homework questions, but this one is different. There are not a lot of great options for this transformation. For the conversion of tertiary amines into secondary amines, classic amine de-alkylation by treatment with cyanogen bromide (BrCN), aka the von Braun reaction,[1] followed by hydrolysis of the resulting cyanamide will work. The alkyl group removed is whichever group is most susceptible to SN2 attack.

Your question is different! von Braun will no longer work for this purpose. The intermediate formed after cyano transfer will simply be deprotonated. A potential solution is to oxidize the secondary amine into an imine, then undergo imine hydrolysis. There are several methods reported for the oxidation, several use catalysts to convert a secondary amine into an imine. I’ve put one in the scheme below. Excess water should release the primary amine from the imine.

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