“Cacodyl”的意思、由来-开放百科全书

词条

Cacodyl

释义

Preparation
History
Applications
References

{{Chembox
| Watchedfields = changed
| verifiedrevid = 433275081
| ImageFileR1 = Cacodyl-from-xtal-1988-3D-balls.png
| ImageNameR1 = Ball and stick model of cacodyl
| ImageFileL1 = Cacodyl Structural Formula V.3.svg
| ImageNameL1 = Structural formula of cacodyl
| IUPACName = Tetramethyldiarsane
| OtherNames = Tetramethyldiarsenic(As—As)

Tetramethyldiarsine

|Section1={{Chembox Identifiers
| CASNo = 471-35-2
| CASNo_Ref = {{cascite|correct|??}}
| PubChem = 79018
| ChemSpiderID = 71351
| ChemSpiderID_Ref = {{chemspidercite|correct|chemspider}}
| EINECS = 207-440-4
| SMILES = [As]([As](C)C)(C)C
| SMILES1 = C[As](C)[As](C)C
| StdInChI = 1S/C4H12As2/c1-5(2)6(3)4/h1-4H3
| StdInChI_Ref = {{stdinchicite|correct|chemspider}}
| InChI = 1/C4H12As2/c1-5(2)6(3)4/h1-4H3
| StdInChIKey = RSKPLCGMBWEANE-UHFFFAOYSA-N
| StdInChIKey_Ref = {{stdinchicite|correct|chemspider}}
| InChIKey = RSKPLCGMBWEANE-UHFFFAOYAG}}
|Section2={{Chembox Properties
| C=4 | H=12 | As=2
| MagSus = -99.9·10⁻⁶ cm³/mol
}}
|Section3={{Chembox Hazards
| MainHazards =
| FlashPt =
| AutoignitionPt = }}
}}

Cacodyl, also known as dicacodyl or tetramethyldiarsine, (CH₃)₂As—As(CH₃)₂, is an organoarsenic compound that constitutes a major part of "Cadet's fuming liquid" (named after the French chemist Louis Claude Cadet de Gassicourt). It is a poisonous oily liquid with an extremely unpleasant garlicky odor. Cacodyl undergoes spontaneous combustion in dry air.

Cacodyl is also the name of the functional group or radical (CH₃)₂As.

Preparation

A mixture of dicacodyl and cacodyl oxide ((CH₃)₂As—O—As(CH₃)₂) was first prepared by Cadet by the reaction of potassium acetate with arsenic trioxide. A subsequent reduction yields a mixture of several methylated arsenic compounds including dicacodyl. The reaction forming the oxide is something like:

A far better synthesis was later developed which started from the dimethyl arsine chloride and dimethyl arsine:

History

Jöns Jakob Berzelius coined the name kakodyl (later modified to cacodyl in English) for the dimethylarsinyl radical, (CH₃)₂As, from the Greek kakodes (evil-smelling) and hyle (matter).^[1]

It was investigated by Edward Frankland and (for over six years) by Robert Bunsen and is considered the earliest organometallic compound ever discovered (even though arsenic is not a true metal).

From it other compounds were made, such as cacodyl fluoride, chloride, et cetera. One compound, cacodyl cyanide, was particularly awful. In Bunsen's words "the smell of this body produces instantaneous tingling of the hands and feet, and even giddiness and insensibility...It is remarkable that when one is exposed to the smell of these compounds the tongue becomes covered with a black coating, even when no further evil effects are noticeable".

Work on cacodyl led Bunsen to the postulation of "methyl radicals" as part of the then-current radical theory.

Applications

Cacodyl was used to try to prove the radical theory of Berzelius, which resulted in a wide use of cacodyl in research laboratories. Afterward interest in the toxic, malodorous compound decreased. During World War I the use of cacodyl as poison gas was considered, but it was never used in the war. Inorganic chemists discovered the properties of cacodyl as a ligand for transition metals.

References

1. ^{{cite journal| title = | author = Berzelius, J. J.| journal = Jahresberichte über die Fortschritte der Physischen Wissenschaften| year = 1839| volume = 18| issue = | pages = 487| doi = }}

{{cite journal

| title = The Crystal Structure of Arsenomethane
| author = John H. Burns and Jürg Waser
| journal = J. Am. Chem. Soc.
| year = 1957
| volume = 79
| issue = 4
| pages = 859–864
| doi = 10.1021/ja01561a020
| hdl = 1911/18207
}}

{{cite journal

| title = Cadet's Fuming Arsenical Liquid and the Cacodyl Compounds of Bunsen
| first = Dietmar
| last = Seyferth
| journal = Organometallics
| year = 2001
| volume = 20
| issue =8
| pages = 1488–1498
| doi = 10.1021/om0101947
| url = http://pubs.acs.org/cgi-bin/abstract.cgi/orgnd7/2001/20/i08/abs/om0101947.html}}

2 : Organoarsenic compounds|Organometallic chemistry

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