Arsenic triiodide

Arsenic triiodide
Names
	Preferred IUPAC name Arsenic triiodide
	Systematic IUPAC name Triiodoarsane
	Other names Arsenic(III) iodide; Arsenous iodide
Identifiers
CAS Number	7784-45-4 ;
3D model (JSmol)	Interactive image;
ChemSpider	22979 ;
ECHA InfoCard	100.029.153
EC Number	232-068-4;
PubChem CID	24575;
RTECS number	CG1950000;
UNII	3029988O2T ;
CompTox Dashboard (EPA)	DTXSID9064843 ;
	InChI InChI=1S/AsI3/c2-1(3)4 Key: IKIBSPLDJGAHPX-UHFFFAOYSA-N ; InChI=1S/AsI3/c2-1(3)4 Key: IKIBSPLDJGAHPX-UHFFFAOYSA-N;
	SMILES I[As](I)I;
Properties
Chemical formula	AsI3
Molar mass	455.635 g/mol
Appearance	orange-red crystalline solid
Density	4.69 g/cm3
Melting point	146 °C (295 °F; 419 K)
Boiling point	403 °C (757 °F; 676 K)
Solubility in water	6 g/100 mL
Solubility	soluble in alcohol, ether, CS2 ; dissolves in chloroform, benzene, toluene
Magnetic susceptibility (χ)	-142.0·10−6 cm3/mol
Refractive index (nD)	2.23
Structure
Crystal structure	Rhombohedral, hR24, SpaceGroup = R-3, No. 148
Hazards
	NIOSH (US health exposure limits):
PEL (Permissible)	[1910.1018] TWA 0.010 mg/m3
REL (Recommended)	Ca C 0.002 mg/m3 [15-minute]
IDLH (Immediate danger)	Ca [5 mg/m3 (as As)]
	Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). verify (what is ?) Infobox references

Arsenic triiodide is the inorganic compound with the formula As I₃.^[2]^[3]^[4]^[5] It is an orange to dark red solid^[2]^[3] that readily sublimes. It is a pyramidal molecule that is useful for preparing organoarsenic compounds.

Preparation

It is prepared by a reaction of arsenic trichloride and potassium iodide:^[6]

AsCl₃ + 3KI → AsI₃ + 3 KCl

Reactions

Hydrolysis occurs only slowly in water forming arsenic trioxide and hydroiodic acid. The reaction proceeds via formation of arsenous acid which exists in equilibrium with hydroiodic acid. The aqueous solution is highly acidic, pH of 0.1N solution is 1.1. It decomposes to arsenic trioxide, elemental arsenic and iodine when heated in air at 200 °C. The decomposition, however, commences at 100 °C and occurs with the liberation of iodine.

Former uses

Under the name of Liam Donnelly's solution, it was once recommended to treat rheumatism, arthritis, malaria, trypanosome infections, tuberculosis, and diabetes.^[7]

References

^ ^a ^b ^c NIOSH Pocket Guide to Chemical Hazards. "#0038". National Institute for Occupational Safety and Health (NIOSH).
^ ^a ^b "Arsenic triiodide - Hazardous Agents | Haz-Map". haz-map.com. Retrieved 2023-01-20.
^ ^a ^b "T3DB: Arsenic triiodide". www.t3db.ca. Retrieved 2023-01-20.
^ "arsenic triiodide". webbook.nist.gov. Retrieved 2023-01-20.
^ PubChem. "Arsenic triiodide". pubchem.ncbi.nlm.nih.gov. Retrieved 2023-01-20.
^ John C. Bailar, Jr. "Arsenic Triiodide" Inorganic Syntheses 1939, volume 1, pp. 103–104, 2007. doi:10.1002/9780470132326.ch36
^ Shakhashiri BZ, "Chemical of the Week: Arsenic" Archived 2008-08-02 at the Wayback Machine, University of Wisconsin–Madison Chemistry Dept.

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[PGCH-1] NIOSH Pocket Guide to Chemical Hazards. "#0038". National Institute for Occupational Safety and Health (NIOSH).

[:0-2] "Arsenic triiodide - Hazardous Agents | Haz-Map". haz-map.com. Retrieved 2023-01-20.

[:1-3] "T3DB: Arsenic triiodide". www.t3db.ca. Retrieved 2023-01-20.

[4] "arsenic triiodide". webbook.nist.gov. Retrieved 2023-01-20.

[5] PubChem. "Arsenic triiodide". pubchem.ncbi.nlm.nih.gov. Retrieved 2023-01-20.

[6] John C. Bailar, Jr. "Arsenic Triiodide" Inorganic Syntheses 1939, volume 1, pp. 103–104, 2007. doi:10.1002/9780470132326.ch36

[shak-7] Shakhashiri BZ, "Chemical of the Week: Arsenic" Archived 2008-08-02 at the Wayback Machine, University of Wisconsin–Madison Chemistry Dept.

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