Treprostinil; 2-(((1R,2R,3aS,9aS)-2-hydroxy-1-((S)-3-hydroxyoctyl)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yl)oxy)acetic acid; CAS No.: 81846-19-7; 2-(((1R,2R,3aS,9aS)-2-hydroxy-1-((S)-3-hydroxyoctyl)-2,3,3a,4,9,9a-hexahydro-1H-cyclopenta[b]naphthalen-5-yl)oxy)acetic acid is a colorless liquid. Store under inert gas at -20 C. This compound is hygroscopic; CAS No.: 81846-19-7 requires desiccant.