Theratuss, Squibb ,US ,1962
Pipazetate Hydrochloride, a pyridobenzothiazine derivative an antiarrhythmic characteristics. Pipazetate is used as a cough supressant.
8.5 parts of 1-azaphenothiazine carboxylic acid chloride and 14 parts of piperidino-ethoxyethanol were introduced into 100 parts of chlorobenzene and the mixture boiled under reflux for 5 minutes. After cooling off the precipitated hydrochloride salt of piperidino-ethoxyethanol was filtered off on a suction filter. Water was added to the filtrate and the pH thereof adjusted to 5 to 6 with dilute HCl. The aqueous phase was then removed, a caustic soda solution added thereto and then extracted with ether. The ethyl extract was washed with water, then dried with potash and the ether distilled off. 9.4 parts of the piperidino-ethoxy-ethyl ester of 1-azaphenothiazine carboxylic acid were obtained. This product was dissolved in 20 parts of isopropanol and the solution neutralized with isopropanolic HCl. The monohydrochloride which precipitated out after recrystallization from isopropanol had a melting point of 160°C to 161°C.
