(S)-ropivacaine hydrochloride hydrate synthesis

84057-95-4

132112-35-7

The general procedure for the synthesis of (S)-N-(2,6-dimethylphenyl)-1-propyl-2-piperidine carboxamide hydrochloride hydrate using (S)-N-(2,6-dimethylphenyl)-1-propylpiperidine-2-carboxamide as raw material was as follows: about 3 g of (S)-N-(2,6-dimethylphenyl)-1 -propyl-2-piperidine carboxamide was dissolved in 10 mL of deionized water and to this solution, 50 mL of acetone preheated to 60°C was slowly added. Under stirring conditions, concentrated hydrochloric acid was added dropwise to adjust the pH to 2.0. Subsequently, the reaction mixture was heated to reflux until a clarified solution was formed. 20 mL of acetone was added to the reaction system and the precipitated solid product was filtered after cooling to room temperature. The solid was washed three times with cold acetone and dried in a vacuum drying oven at 40°C for 12 h. 2.9 g of white crystalline (S)-N-(2,6-dimethylphenyl)-1-propylpiperidine-2-carboxamide hydrochloride hydrate was obtained in 82% yield. The water content of the product was 5.6% as determined by Karl Fischer's method.