Ammonia → 1-(2,2,2-Trifluoroethyl)piperidin-4-amine

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Reaction Steps

A 25% aqueous solution of ammonia (170 mL), 10% Pd/C (7.4 g), and a solution of the above 1-(2,2,2-trifluoroethyl)piperidin-4-one/butanol mixture (72.5 g, 0.344 mol, 86:14 weight ratio) in methanol (420 mL) were placed into a 2 L glass autoclave purged with argon. The reaction mixture was hydrogenated in a Parr apparatus at a hydrogen pressure of 40 psi for 18 h. The catalyst was removed by filtration. The filtrate was concentrated in vacuo to 150 mL. Potash (46 g) and ether (200 mL) were added, and the mixture was vigorously stirred for 20 min. The organic layer was separated, and the aqueous one was extracted with ether (100 mL). The combined organic layers were dried over anhydrous Na2SO4 and evaporated to afford a mixture (74.4 g) of 1-(2,2,2-trifluoroethyl)piperidin-4-amine and 1-(2,2,2-trifluoroethyl)-N-[1-(2,2,2-trifluoroethyl)piperidin-4-yl]piperidin-4-amine in 72:28 weight ratio (containing butanol). This mixture was fractionated at 7-8 mmHg on a 15 cm Vigreaux column (a fraction with bp 75-95° C. was collected) to afford 1-(2,2,2-trifluoroethyl)piperidin-4-amine (38.5 g) as a colorless liquid.

Provenance & Evidence