To a suspension of sodamide in liquid ammonia is added of 2-
buterylphenothiazine. After stirring for one hour, there is added 1-bromo-3-
chloropropane. The ammonia is allowed to evaporate and the residue is
diluted with the water. The mixture is extracted with ether and the ether
solution is dried over anhydrous sodium sulfate, filtered and concentrated. The
residue consists of crude 10-(3-chloropropyl)-2-buterylphenothiazine as
viscous oil and is used in the next step without further purification.
A mixture of 1-methylpiperazine and crude 10-(3-chloropropyl)-2-
buterylphenothiazine is heated on a steam bath for 18 hours. The mixture is
diluted with the water and extracted with ether. The ether solution is
extracted with dilute hydrochloric acid. The aqueous acid solution is made
alkaline with sodium hydroxide and the product is extracted with ether. The
ether extracts are dried and concentrated to a residue consisting of the free
base 2-butyryl-10-(3-(4-methyl-1-piperazinyl)propyl)phenothiazine.
