Title: Arsenic Triiodide
CAS Registry Number: 7784-45-4
Molecular Formula: AsI3
Molecular Weight: 455.64
Percent Composition: As 16.44%, I 83.56%
Literature References: Prepd from the elements or from AsCl3 and KI: Bailar, Inorg. Synth. I, 103 (1939).
Properties: Orange-red, trigonal rhombohedra from acetone. Reacts slowly with O2 from air, liberating iodine. d425 4.688. Some tendency to sublime below 100°. mp 140.9° forming a red liquid. bp760 ~400°. One gram dissolves in 12 ml water forming a yellow soln. Does not hydrolyze rapidly and may be recovered from the water soln unchanged within 5 hrs. Aqueous solns are strongly acid (pH of 0.1N soln about 1.1) and ultimately form HI and As2O3, although an equilibrium AsI3 + 3H2O = H3AsO3 + 3HI has been observed. Freely sol in carbon disulfide, chloroform, benzene, toluene, xylene. Less sol in alc, ether.
Melting point: mp 140.9° forming a red liquid
Boiling point: bp760 ~400°
Density: d425 4.688
Therap-Cat: Formerly in dermatitides.