While somewhat difficult to handle due to its corrosive character, arsenic trichloride has certain solvent properties which make it a useful addition to the list of spectroscopic solvents. Conductiometric titrations have been made using this halide as a solvent (2). The hydrolysis of this chloride to arsenous acid is a reversible reaction unlike the behavior of such a related halide as phosphorus trichloride. It is possible to steam distill arsenic trichloride and it forms no basic salt on hydrolysis. We have found that a clear solution in water can be formed with the halide up to 0.5 per cent by volume of water. Concentrated hydrochloric acid solutions in arsenic trichloride have been found to give spectra similar to that of water in the halide.
Herman A. Szymanski, Alvin Bluemle, and William Collins, "Arsenic Trichloride and Arsenic/Antimony Chlorides as Solvents for Infrared and N.M.R. Spectroscopy," Appl. Spectrosc. 19, 137-139 (1965)