andra - 20-10-2011 at 05:08
Has anyone any ideas of how to add imidazole (imidazole derivatives) to the primary amine of a polymer (well to be more specific to chitosan (=a
linear polysaccharide composed of randomly distributed β-(1-4)-linked D-glucosamine and N-acetyl-D-glucosamine).
fledarmus - 20-10-2011 at 05:41
Have you tried doing a direct coupling with, eg, bromoimidazole? I have been able to couple several brominated heteroaromatic systems to primary or
secondary amines just with heat in DMF. The free hydroxy in the chitosan might be a problem, however.
andra - 20-10-2011 at 05:57
I haven't tried anything yet...just been researching and was thinking to try adding 1H-Imidazole-5-acetaldehyde to forme the amine and than do the
reduction with NaBH3CN???
someone also suggested to think about isocyanates, but am not sure how to use isocyanates to add imidazole to chitosan.
fledarmus - 20-10-2011 at 08:43
Yes, if you don't need the imidazole directly attached to the amine you could do the reductive amination with sodium cyanoborohydride or sodium
triacetoxyborohydride. You could also do an amide linkage with the imidazole carboxylic acid.
Isocyanates will react with carbonyl groups to form imidazoles, but I usually see that on aldehydes. Perhaps he is thinking that you could attach a
formyl group to your amine and react that with the isocyanate?
andra - 24-10-2011 at 22:53
I asked again about the imidazole and the izocyanates and he was suggesting to look for a imidazole isocyanate derivative, because the addition of the
isocyanate to the primary amine is straight forward (DMF, 0 C, overnight room temp) and we don't have to worry about the OH group.
However, I can't find any commercial ones
could you help me with that? what do you
think about this idea?
However, in the mean time I'm going to perform the addition of the 1H-Imidazole-5-acetaldehyde to forme the amine and than do the reduction with
NaBH3CN.
I don't know what to say about the bromoimidazole, because as you said I'm afraid it will attack also the OH.