[Toast]

I am in need of advice in purifying a rather tricky reagent.

We purchased a bottle of 2,4-diaminopyrimidine from a particular vendor we frequent, and the quality of the reagent is reasonable, but needs purification before use.  Its soluble in water, even at pH extremes and non-extremes, as well as methanol.  When ran on silica TLC, three peaks appear, and the one that is representative of product (pdt) hardly budges off baseline in 25%MeOH/DCM as well as in 6:1:1:.5 EtOAc/Acetone/MeOH/H2O.   

I've considered re-crystallization, but am not quite sure where to start (Maybe trying hot EtOAc, but unsure). 

Has anyone worked with 2,4-diaminopyrimidine before, and/or can recommend a purification method that would be advantageous to try?

Thank you.

[clarkstill]

Best I could find is a patent:

https://patents.google.com/patent/US2416617

They treat the crude material with sulfuric acid, then "The crude 2,4-diaminopyrimidine sulfate can be recrystallized from six times its Weight of hot water, with treatment by activated charcoal to give a pure, white product. "

[Toast]

While the freebasing sounds like something fun and new for me, I'd like to avoid sulfuric acid.  The patent does mention extraction of the pure pdt from residue with hot EtOAc, so I might give that a go with the crude of the reagent bottle, and hot filter off any material that doesn't dissolve.

Thank you for finding that.