Arsenic Oxychloride, AsOCl

Arsenic Oxychloride (Arsenyl Chloride), AsOCl, may be obtained in solution by passing hydrogen chloride into an aqueous suspension of arsenious oxide, or by boiling together molecular proportions of arsenic trichloride and arsenious oxide, the process being continued in each case until the oxide is dissolved. On gently distilling the solution until it begins to foam, the oxychloride separates as a brown viscous mass; if the distillation is carried out at a higher temperature the deposit has the composition AsOClAs₂O₃. The monohydrate, AsOClH₂O, may be obtained by allowing a solution of the trichloride in water to crystallise slowly. It separates in stellate aggregates. With ammonium chloride the oxychloride reacts to form the double compound AsOCl.2NH₄Cl.