The general procedure for the synthesis of N-hydroxypropionic acid amidine from propionitrile was as follows: hydroxylamine hydrochloride (18.9 g, 272.7 mmol) and anhydrous potassium carbonate (37.6 g, 272.7 mmol) were suspended in a mixed solvent of ethanol/water (200 mL/50 mL), and stirred for 1 h at room temperature. Subsequently, propionitrile (10.0 g, 181.8 mmol) was added to the reaction system. The reaction mixture was heated to reflux and stirred continuously for 20 h. The reaction process was monitored by thin layer chromatography (unfolding agent: dichloromethane/methanol, 50/1 volume ratio). Upon completion of the reaction, the inorganic salts were removed by filtration and the filtrate was concentrated under reduced pressure to afford N-hydroxypropionic acid amidine (13.5 g, 81% yield) as a light yellow solid.
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