4-Piperidinecarboxylic acid → 1-Acetylpiperidine-4-carboxylic acid

Participants

Reaction Steps

100 g of piperidine-4-carboxylic acid were heated under reflux and with stirring at a temperature of 135° C. for 4 hours in 400 ml of acetic anhydride. The mixture was then allowed to cool to room temperature. To work up the reaction mixture it was evaporated to remove acetic anhydride, toluene being added several times towards the end of the evaporation. After the evaporation a beige-colored solid crude product remained as a residue. This was suspended in 300 ml of a mixture of diisopropyl ether and dichloromethane, cooled to a temperature of 0° C. and filtered. 65 g of crude acetylpiperidine-4-carboxylic acid having a melting point of 180° to 182° C. were obtained. The filtrate was diluted while hot with 200 ml of water, and further 1-acetylpiperidine-4-carboxylic acid deposited as a precipitate and was filtered out. 42.91 g of the acid were obtained, so that the total yield of 1-acetylpiperidine-4-carboxylic acid was 107.9 g.

Provenance & Evidence