Arsenic trichloride: Difference between revisions

{{Chembox

| verifiedrevid = 438487761

| Name = Arsenic trichloride

| ImageFile = Arsenic-trichloride-3D-balls.png

| ImageName = Ball-and-stick model of arsenic trichloride

| OtherNames = Arsenic(III) chloride, Arsenous trichloride, Arsine trichloride, Butter of arsenic, de Valagin's solution, Trichloroarsine

|Section1={{Chembox Identifiers

| InChI = 1/AsCl3/c2-1(3)4

| CASNo_Ref = {{cascite|correct|CAS}}

| PubChem = 24570

| RTECS = CG1750000

| UNNumber = 1560

| EC_number = 232-059-5

| UNII = 5XW39M1300

|Section2={{Chembox Properties

| Formula = AsCl₃

| MolarMass = 181.28 g/mol

| Appearance = colourless oily liquid

| Density = 2.163 g/cm³, liquid

| Solubility = Hydrolyzes

| SolubleOther = soluble in [[ethanol|alcohol]], [[diethyl ether|ether]], [[hydrochloric acid|HCl]], [[hydrobromic acid|HBr]], [[chloroform]], [[carbon tetrachloride|CCl₄]]<ref name="crc">{{cite book |author1=John Rumble |title=CRC Handbook of Chemistry and Physics |date=June 18, 2018 |publisher=CRC Press |isbn=978-1138561632 |pages=4–41|edition=99th |language=English}}</ref>

| MeltingPtC = −16.2

| BoilingPtC = 130.2

| RefractIndex = 1.6006

| Viscosity = 9.77 x 10⁻⁶ Pa s

| MagSus = -79.9·10⁻⁶ cm³/mol

|Section7={{Chembox Hazards

| MainHazards = Very toxic, carcinogen, corrosive, decomposes on contact with water releasing [[hydrochloric acid|HCl]]

| GHSPictograms = {{GHS05}}{{GHS06}}{{GHS08}}{{GHS09}}

| GHSSignalWord = Danger

| HPhrases = {{H-phrases|301|310|314|331|350|410}}

| PPhrases = {{P-phrases|201|202|260|261|262|264|270|271|273|280|281|301+310|301+330+331|302+350|303+361+353|304+340|305+351+338|308+313|310|311|321|322|330|361|363|391|403+233|405|501}}

| NFPA-H = 4

| NFPA-R = 1

| NFPA-F = 0

| LD50 = 48 mg/kg

| LCLo = 100 mg/m³ (cat, 1 hr)<br/>200 mg/m³ (cat, 20 min)<br/>338 ppm (rat, 10 min)<ref>{{IDLH|7440382|Arsenic (inorganic compounds, as As)}}</ref>

| IDLH = Ca [5 mg/m³ (as As)]<ref name=PGCH>{{PGCH|0038}}</ref>

| REL = Ca C 0.002 mg/m³ [15-minute]<ref name=PGCH/>

| PEL = [1910.1018] TWA 0.010 mg/m³<ref name=PGCH/>

|Section8={{Chembox Related

| OtherAnions = [[Arsenic trioxide]], [[Arsenic trifluoride]]

| OtherCations = [[Antimony trichloride]]

| OtherFunction =

| OtherFunction_label =

| OtherCompounds = }}

'''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 compound]]s.<ref name=Ullmann>Sabina C. Grund, Kunibert Hanusch, Hans Uwe Wolf "Arsenic and Arsenic Compounds" in ''Ullmann's Encyclopedia of Industrial Chemistry'', VCH-Wiley, 2008, Weinheim.{{doi|10.1002/14356007.a03_113.pub2}}</ref>

AsCl₃ is a pyramidal molecule with C_3v [[symmetry group|symmetry]]. The As-Cl bond is 2.161 Å and the angle Cl-As-Cl is 98° 25'±30.<ref>P. Kisliuk; C. H. Townes. "The Microwave Spectra and Molecular Structure of Phosphorus and Arsenic Trichloride". ''J. Chem. Phys.'' 1950, 18.</ref><ref>Jean Galy; Renee Enjalbertl Pierre Lecante; Andrzej Burian "AsCl₃: From the crystalline to the liquid state. XRD (176< T (K) < 250) and WAXS (295K) studies" ''Inorg. Chem'' 2002, volume 41, pp. 693–698.{{doi|10.1021/ic0102788}}</ref> AsCl₃ has four normal modes of vibration: ν1(A₁) 416, ν2(A₁) 192, ν3 393, and ν4(E) 152&nbsp;cm⁻¹.<ref>Klapoetke, Thomas M. "The vibrational spectrum of arsenic trichloride" ''Main Group Metal Chemistry'' 1997, volume 20, pp. 81–83.</ref>

It can also be prepared by chlorination of arsenic at 80–85&nbsp;°C, but this method requires elemental arsenic.<ref name=Ullmann/>

Arsenic trichloride can be prepared by the reaction of arsenic oxide and sulfur monochloride. This method requires simple apparatus and proceeds efficiently:<ref>R. C. Smith, "Manufacture of Arsenic trichloride" ''The Journal of Industrial and Engineering Chemistry'' 1919, volume 11, pp. 109–110. {{doi|10.1021/ie50110a009}}</ref>

A convenient laboratory method is refluxing arsenic(III) oxide with [[thionyl chloride]]:<ref>{{cite journal |first1=S. K.| last1=Pandey |first2=A. |last2=Steiner |first3=H. W. |last3=Roesky |title=Arsenic(III) chloride | journal=Inorganic Syntheses | year=1997|volume=31|page=148-150|doi=10.1002/9780470132623.ch24}}</ref>

: 2 As₂O₃ + 3 SOCl₂ → 2 AsCl₃ + 3 SO₂

Arsenic trichloride can also be prepared by the reaction of hydrochloric acid and arsenic(III) sulfide.

:As₂S₃ + 6 HCl → 2 AsCl₃ + 3 H₂S

[[Hydrolysis]] gives [[arsenous acid]] and [[hydrochloric acid]]:

Although AsCl₃ is less moisture sensitive than PCl₃, it still fumes in moist air.<ref>Holleman, A. F.; Wiberg, E. ''Inorganic Chemistry'' Academic Press: San Diego, 2001. {{ISBN|0-12-352651-5}}.</ref>

AsCl₃ undergoes redistribution upon treatment with As₂O₃ to give the [[inorganic polymer]] AsOCl. With chloride sources, AsCl₃ also forms salts containing the anion [AsCl₄]⁻. Reaction with [[potassium bromide]] and potassium iodide give [[arsenic tribromide]] and [[arsenic triiodide]], respectively.

AsCl₃ is useful in organoarsenic chemistry, for example [[triphenylarsine]] is derived from AsCl₃:<ref name=Shriner>{{OrgSynth | author = Shriner, R. L. |author2=Wolf, C. N. | title = Tetraphenylarsonium Chloride Hydrochloride | collvol = 4 | collvolpages = 910 | year = 1963 | prep = cv4p0910}}. Describes the preparation of As(C₆H₅)₃.</ref>

:AsCl₃ + 6 Na + C₆H₅Cl → As(C₆H₅)₃ + 6 NaCl

The chemical weapons called [[Lewisite]]s are prepared by the addition of arsenic trichloride to acetylene:

:{{chem2|AsCl3 + C2H2 -> ClCH\dCHAsCl2}}

Inorganic arsenic compounds are highly toxic,<ref name=Ullmann/> and AsCl₃ especially so because of its volatility and solubility (in water).

It is classified as an [[List of extremely hazardous substances|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.<ref name="gov-right-know">{{Cite report | publisher = [[United States Government Publishing Office|Government Printing Office]] | title = 40 C.F.R.: Appendix A to Part 355—The List of Extremely Hazardous Substances and Their Threshold Planning Quantities | url = http://edocket.access.gpo.gov/cfr_2008/julqtr/pdf/40cfr355AppA.pdf | edition = July 1, 2008 | access-date = October 29, 2011 | archive-url = https://web.archive.org/web/20120225051612/http://edocket.access.gpo.gov/cfr_2008/julqtr/pdf/40cfr355AppA.pdf | archive-date = February 25, 2012 | url-status = dead }}</ref>

{{Chlorides}}

[[Category:Arsenic(III) compounds]]

[[Category:Arsenic halides]]