A solution of 2,4-dichloro-5-(trifluoromethyl)pyrimidine (70 g, 322.61 mmol) in THF (1.4 L) was treated with a solution of ethanolamine (32 g, 709.74 mmol, 46.37 mL) in THF (100 mL) at 0°C, dropwise under N2, over 1 hour. Once the addition was complete, the mixture was stirred at 25°C for 1 hour. The mixture was then filtered and concentrated under reduced pressure to obtain a residue. The residue was subsequently triturated with DCM (200 mL) and filtered. The filtrate was recrystallized with a mixture of n-heptane (600 mL) and MTBE (400 mL). The resulting phase was syrup-like in consistency, and the liquid phase was discarded. The syrup residue was further purified by silica gel column chromatography (PE: EtOAc=20:1) to yield 4-chloro-N-ethyl-5-(trifluoromethyl) pyrimidine-2-amine as a white solid.
