Hi all, I need to cleave the ester in Ethyl 2-amino-1H-imidazole-5-carboxylate to make the carboxylic acid and retrieve the product from solution to use in downstream applications of linking to amines via reductive amination using sodium cyanoborohydrde.
I tried to cleave the ester with 2M equivalents of KOH in 5:1 MeOH:H2O for 1H at 40C. After 1H, i added 20mL H2O to quench and then tried to precipitate my newly made acid by dropping pH to 1, however nothing precipitated out. I then tried to see if any of my product was unreacted by mixing with diethyl ether to see if any of the light brown color would transfer to the ether layer, but again, nothing happened, the ether layer is completely clear. I guess I should just boil off some water and see if it starts to precipitate out? Im not much of a chemist so I just wanted to make sure I havent made any terrible assumptions along the way...
Your product has both acid and base elements. So it is only gong to dissolve in water. At low pH the imidazole and / or the amine will be protonated and cationic. At high pH the acid will be a carboxylate. It is an amino acid! there will be a pI where the zwitterion has the maximum concentration.
maybe if you do the hydrolysis in ammonium hydroxide you can lyophiize.
Dear Nikhil Goel please check the link below for separation of zwitterion from water:
https://www.researchgate.net/post/How-to-desalt-zwitterions
It is a very interesting old problem.
Compound 25 is yours: Saponification
A solution of Ethyl 2-amino-1H-imidazole-5-carboxylate (1.82 g, 11.7 mmol, 1.0 eq.) in THF (30 mL) was treated with NaOH (2.34 g, 58.5 mmol, 5.0 eq.) in H2O (10 mL) and stirred for 17 h at room temperature. Then, the reaction mixture
was neutralised by addition of a 2 M solution of HCl. The resulting precipitate was filtered off, dried in vacuo and recrystalised in semiconcentrated HCl. The title compound 25 (1.43 g, 8.74 mmol, 75%) was
obtained as a brownish solid.
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