Piptal ,Merrell National ,US ,1955
N-ethyl-3-chloropiperidine was prepared according to the method of Fuson and Zirkle described in Volume 70, J. Am. Chem. Soc., p 2760. 12.0 g (0.081 mol) of N-ethyl-3-chloropiperidine was mixed with 18.6 g (0.081 mol) of benzilic acid and 80 cc of anhydrous isopropyl alcohol as a solvent. The mixture was refluxed for 72 hours. The solution was then filtered and concentrated at 30 mm of mercury. The concentrate was dissolved in water, acidified with hydrochloric acid and extracted with ether to remove theThe aqueous layer was neutralized with sodium bicarbonate and the product was extracted with ether. The ethereal solution of the product was dried with potassium carbonate, the ether was removed by distillation and the residue was distilled at 0.12 to 0.18 mm of mercury, the BP being 194° to 198°C. A yield of 16.5 g (60% of theoretical) of N-ethyl-3-piperidyl-benzilate was obtained.
34 g (0.1 mol) of the basic ester is dissolved in 75 cc of isopropyl alcohol and treated with 9.5 g (0.1 mol) of methyl bromide. The mixture is allowed to stand at room temperature until precipitation is complete. The product is removed by filtration and washed with isopropyl alcohol, yield 33 g, MP 175° to 177°C. On recrystallization from isopropyl alcohol, the MP was raised to 179° to 180°C dec.
