Chromatography Forum

I am trying to purify a quite complicated mixture containing polyamines of similar polarities. This is a result of several steps of synthesis, many of which purification could not be done on. My desired product is a polyamine, which has an aromatic group in it. I am wondering if there is some way I can take advantage of the aromatic in purification. I have tried silica gel chromatography, and it does not seem to work- I have to use concentrated NH3 to even get this molecule to budge.
Thanks for your help.
Brooke

A polyamine sticks to silica usually rather strongly. However, there should be two ways to get it to move. You have tried ammonia as a competing base, and were not happy. You could also try an inorganic acid (to make the silanols not ionized) together with methanol or methanol/water as carriers.

The other thought is to try a polymeric column where there is no silanol interaction to content with. Perhaps a PRP-1 column might be a good choice. Just a quick thought.

Regards,
Mark