Oxophenarsine hydrochloride

After the death of EhrKch in 1915, research into the organoarsenicals continued, and it was discovered that, in the body, Salvarsan was oxidized to oxophenarsine hydrochloride 4 (marketed as Mapharsen ). Since this compotmd was stable in air, it gradually replaced Salvarsan for therapeutic use, to the point where it became the predominant organoarsenic medicine during the 1930s. 

---