Arsenic(III) chloride, Arsenous trichloride, Butter of arsenic, de Valagin's solution
3D model (JSmol)
CompTox Dashboard (EPA)
|Molar mass||181.28 g/mol|
|Density||2.163 g/cm3, liquid|
|Melting point||−16.2 °C (2.8 °F; 256.9 K)|
|Boiling point||130.2 °C (266.4 °F; 403.3 K)|
|Solubility||soluble in alcohol, ether, HCl, HBr|
Refractive index (nD)
|Viscosity||9.77 x 10−6 Pa s|
|GHS Signal word||Danger|
|H301, H301, H310, H314, H331, H350, H400, H410|
|P201, P202, P260, P261, P262, P264, P270, P271, P273, P280, P281, P301+310, P301+330+331, P302+350, P303+361+353, P304+340, P305+351+338, P308+313, P310, P311, P321, P322, P330, P361, P363|
|NFPA 704 (fire diamond)|
|Lethal dose or concentration (LD, LC):|
LD50 (median dose)
LCLo (lowest published)
|100 mg/m3 (cat, 1 hr)|
200 mg/m3 (cat, 20 min)
338 ppm (rat, 10 min)
|NIOSH (US health exposure limits):|
|[1910.1018] TWA 0.010 mg/m3|
|Ca C 0.002 mg/m3 [15-minute]|
IDLH (Immediate danger)
|Ca [5 mg/m3 (as As)]|
|Arsenic trioxide, Arsenic trifluoride|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|what is ?)(|
Arsenic trichloride is an inorganic compound with the formula AsCl3, also known as arsenous chloride or butter of arsenic. This poisonous oil is colourless, although impure samples may appear yellow. It is an intermediate in the manufacture of organoarsenic compounds.
AsCl3 is a pyramidal molecule with C3v symmetry. The As-Cl bond is 2.161 Å and the angle Cl-As-Cl is 98° 25'±30. AsCl3 has four normal modes of vibration: ν1(A1) 416, ν2(A1) 192, ν3 393, and ν4(E) 152 cm−1. Arsenic trichloride contains predominantly covalent bonds, which explains its low melting point.
It can also be prepared by chlorination of arsenic at 80–85 °C, but this method requires elemental arsenic.
Arsenic trichloride can also be prepared by the reaction of arsenic oxide and sulfur monochloride. This method requires simple apparatus and proceeds efficiently:
Although AsCl3 is less moisture sensitive than PCl3, it still fumes in moist air.
AsCl3 undergoes redistribution upon treatment with As2O3 to give the inorganic polymer AsOCl. With chloride sources, AsCl3, forms salts containing the anion [AsCl4]−. Reaction with potassium bromide and potassium iodide give arsenic tribromide and arsenic triiodide, respectively.
Arsenic compounds are highly toxic, and AsCl3 especially so because of its volatility and solubility.
It is classified as an extremely hazardous substance in the United States as defined in Section 302 of the U.S. Emergency Planning and Community Right-to-Know Act (42 U.S.C. 11002), and is subject to strict reporting requirements by facilities which produce, store, or use it in significant quantities.