1-METHYL-PIPERIDINE-4-CARBOXYLIC ACID

498-94-2

50-00-0

68947-43-3

Using 4-piperidinecarboxylic acid (1 kg, 7.74 mol) and formaldehyde (37% aqueous solution, 720 g, 8.87 mol, 1.15 eq.) as feedstock, a wet Pd/C catalyst (10%; 55% paste, 100 g) was added to 10 L of water and the mixture was transferred to a stainless steel hydrogenation reactor. The reactor was pressurized with hydrogen (3 bar) and the reaction mixture was reacted overnight at 16-25 °C with a stirring speed of 200-2500 rpm. Upon completion of the reaction, the catalyst was removed by filtration and the filtrate was washed with 500 mL of water and subsequently concentrated under vacuum. The residue was azeotropically distilled by ethanol (2 x 1 L) to remove residual water. Finally, the resulting solid was dried under vacuum at 50 °C overnight to afford 1-methylpiperidine-4-carboxylic acid as an off-white solid (1087 g, 98.1% yield).