Hi. I'm trying to make a reaction between a polymer whose end group is an alcohol and a biomolecule through the amine function. I have already thought of using coupling agents, such as CDI or EDC, however the information I find is that they are used to link a carboxylic acid and an amine forming an amide. Has anyone tried to do this reaction using an alcohol and an amine?
It won't work. You have to activate the hydroxyl group first. For this, several protocols are available. You can use epoxides or carbonyldiimidazole for activation. Hermanson's book (Bioconjugate techniques) will give you all the details
First I would react the OH functional polymer with a diisocyanate which has two isocyanate groups of different reactivity like IPDI or 2,4-toluylene diisocyanate.
2 O=C=N-R-N=C=O + HO------OH -> (isocyanate terminated prepolymer)
O=C=N-R-NH-CO-O------O-CO-NH-R-N=C=O + 2 H2N-B (aminof. biomolecule) ->
B-NH-CO-NH-R-NH-CO-O------O-CO-HN-R-NH-CO-NH-B
The first reaction (formation of isocyanate terminated prepolymer) can be made in neat at 80°C with 0.1% dibutyltin dilaurate (DBTL) as catalyst. If tin is a problem you can also use DABCO as catalyst. The second reaction with the amine functional biomolecule proceeds at room temperature immediately, even in aqueous phase in which the isocyanate terminated prepolymer is stable for some minutes.
Dr. Koehler has given the answer. First the reaction with -OH to make isocyanate terminated polymer, which will be reacted with amine. The stoichiometry needs to be correct. Otherwise it may undergo crosslinking. You may also react tetraethoxy silane with both hydroxyl and amine together. Oxalyl chloride can also react with both hydroxyl and amine.
You can get a weak reaction between anhydrous primary alcohol and some anhydrous primary amines, but the adduct is not stable, cannot be distilled, and is easily reversed unless the complex is precipitated and dried. With a biomolecule the ammonium product probably doesn't form, but the alcohol might damage the biomolecule.
I would like to make reaction between an aminopropyl imidazole and an OH-functionalized silica nanoparticles. can i in this case follow the same procedure of isocyanate or there is an other simple possibility?
thank you
- Badges
- Science topic
- Similar topics
- Chemistry
- Biochemistry
- Biomolecules