2,2’-Bs(trifluoromethyl)-10H-3,10'-biphenothiazine is an impurity in the synthesis of 2-(4-(3-(2',8-Bis(trifluoromethyl)-10H-[3,10'-biphenothiazin]-10-yl)propyl)piperazin-1-yl)ethanol (B586700), an impurity of Fluphenazine Decanoate (F598350) which is used in psychotropic drug treatments like those relating to schizophrenia.