I am trying to make oligomers using alkyl dialdehydes and alkyl diamines. But so far I can't find precedent researches on it. There is either conjugated system involved or post-polymerization modification. The imine formation never works, I haven't spotted the imine proton/carbon peaks yet. When I thought I did, the peak shifted the next time I did the same reaction.
I had problems of side reaction called Retro-michael reaction before and I extended the length of the alkyl aldehyde, the problem was solved. But still every time I add amine (tried several non-aromatic amines) to the aldehyde, the aldehyde peak disappears fast (10 min) and all the peaks broaden after a few hours. I use dry THF and molecular sieves for this reaction.
Thank you for reading this. Any suggestion would be appreciated.
I don't know for sure, but aldehydes can react with themselves, especially in the presence of a base. Maybe, your amines are just a catalyst for aldol condensation. You could try it the other way: add aldehydes to an excess of amines. Then, it should be less likely that aldehydes react with themselves. If you have a possibility to check whether your educts are consumed (chromatography), could be helpful.
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