Diphenylchloroarsine

diphenylarsenyl chloride, (C₆H₅)₂AsCl; colorless crystals. Melting point, ~38°C; boiling point, 333°C; density, 1.3870 g/cm³ (42°C); index of refraction n_D⁵⁶, 1.6332. It is insoluble in water but readily soluble in most organic solvents. It reacts readily with water and alkalies and oxidizes rather readily. It is made by reducing diphenylarsenic acid, (C₆H₅)₂AsO(OH), with sulfur dioxide in concentrated hydrochloric acid.

In the form of smoke or vapor, diphenylchloroarsine irritates the upper respiratory passages, causing uncontrollable sneezing and coughing (unendurable concentration, 1 mg/m³). During World War I it was extensively used by Germany as a poison under the code name Klark I.