Arsphenamine
![The structure of Arsphenamine has been proposed to be akin to the azobenzene (A), but mass spectral studies published in 2005 suggest[1] it is actually a mixture of the trimer B and the pentamer C.](/uploads/202412/21/Salvarsan-montage3351.png)
Arsphenamine, also known as Salvarsan or compound 606, is a drug that was introduced at the beginning of the 1910s as the first effective treatment for syphilis, and was also used to treat trypanosomiasis. This organoarsenic compound was the first modern chemotherapeutic agent.