What is the best condition and solvent to attach acyl halide ( methacryloyl chloride) derivative of carbamide(allantoin)?
So far I tried with the following solvents DMSO, MeOH, DMF, DCM. But no satisfactory result. Pyridine and Et3N were used as the base. Also tried with 50 and 70 degree c temperature for 4/5 hours. But got nothing satisfactory from the 1H-NMR.
The reaction in DMF with ET3N base attached.
There are many ways that this reaction can go wrong. You don't really say what you obtained, but I imagine it was a complex mixture. The most reactive site on the allantoin is the 1 position on your diagram. However I believe that the product of the acylation of this site is not stable and will hydrolyze. MeOH, DMSO and DMF react with acid chlorides so do not use these. You might try pyridine as a solvent, just filter off the pyridine HCl solids before trying to isolate the product. You could try Schotten-Baumann conditions (DCM or EtOAc with aqueous base, like carbonate). You have multiple sites of reaction in the allantoin, any NH essentially, but without knowing how it is to be used, that may not make a difference for your incorporation of it into a polymer.
William Harter Thanks a lot for your suggestion. As I am doing the reaction in an inert atmosphere there is very little chance for the product to get hydrolyzed. If so, shouldn't I see at least a bit of product in the NMR? For better yield maybe then I can confirm it to the highest inert condition.
Isn't DMF the typical solvent for acid chloride and amine reaction? As far as I know, it's just forming an unstable intermediate.
For Schotten-Baumann conditions the product will go to the aqueous phase, but allantoin is only 4%(maybe) soluble in water. So will it be effective?
DMF is not a typical solvent for acid chlorides and amines. DMF can react with acid chlorides to form a Vilsmeier reagent and that is not what you want here. DCM is much more common for acid chloride amidations. For the Schotten-Baumann conditions, I would expect the product would stay in the organic phase with your reagents. The allantoin can react on multiple sites so I would expect a complex mixture. I believe the most active site is the amine between the two cabonyls. However reaction at this N would easily hydrolyze back to the starting material with water. You should see some reaction with pyridine as the solvent.
I will definitely try that with pyridine. Why do you think that amine is the most reactive amine?
Also, what do think the reason behind it that the reaction didn't work also with DCM as a solvent? Allantoin is not soluble in DCM.
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