Cacodyl cyanide

Cacodyl cyanide is a highly poisonous organoarsenic compound discovered by Robert Bunsen in the 1840s.[3][4][5] It is very volatile and flammable, as it shares the chemical properties of both arsenic and cyanide.

Cacodyl cyanide
Cacodyl cyanide.svg
Preferred IUPAC name
Dimethylarsinous cyanide
Other names
Cyanide of cacodyl
3D model (JSmol)
RTECS number
  • CH2100000
  • InChI=1S/C3H6AsN/c1-4(2)3-5/h1-2H3
  • C[As](C)C#N
Molar mass 131.010 g·mol−1
Appearance White solid
Melting point 33 °C (91 °F; 306 K)
Boiling point 140 °C (284 °F; 413 K)
Slightly soluble
Solubility Very soluble in alcohol and ether
Occupational safety and health (OHS/OSH):
Main hazards
Extremely toxic
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).


Cacodyl cyanide can be prepared by reaction of cacodyl oxide with hydrogen cyanide or mercuric cyanide.[6]


Cacodyl cyanide is a white solid that is only slightly soluble in water, but very soluble in alcohol and ether.[6]

Cacodyl cyanide is highly toxic, producing symptoms of both cyanide and arsenic poisoning. Bunsen described it[7] in the following terms;

This substance is extraordinarily poisonous, and for this reason its preparation and purification can only be carried on in the open air; indeed, under these circumstances, it is necessary for the operator to breathe through a long open tube so as to insure the inspiration of air free from impregnation with any trace of the vapor of this very volatile compound. If only a few grains of this substance be allowed to evaporate in a room at the ordinary temperature, the effect upon any one inspiring the air is that of sudden giddiness and insensibility, amounting to complete unconsciousness.

It is also explosive, and Bunsen himself was severely injured in the course of his experiments with cacodyl cyanide. The Russian military tested cacodyl cyanide on cats as a potential chemical weapon for filling shells in late 1850s, but while it was found to be a potent lachrymatory agent, all cats survived and it was ultimately considered unsuitable for military use.[8][9][10] Any experiment or contact with cacodyl cyanide requires extreme care and caution as it is highly dangerous.

See alsoEdit


  1. ^ Britton, D.; Young Junior, V.G.; Schlemper, E.O. (2002). "CSD Entry: CNMARS01". Cambridge Structural Database: Access Structures. Cambridge Crystallographic Data Centre. doi:10.5517/cc69jss. Retrieved 2022-08-10.
  2. ^ Britton, D.; Young, V. G.; Schlemper, E. O. (2002). "Intermolecular interactions in cyanodimethylarsine and cyanodimethylstibine". Acta Crystallogr. C. 58 (5): m307–m309. doi:10.1107/S0108270102006030. PMID 11983976.
  3. ^ Lee FA, Thing C, Dehn WM (1923). "Some cacodyl derivatives". J. Am. Chem. Soc. 45 (12): 2996–2998. doi:10.1021/ja01665a027.
  4. ^ Morgan GT, Yarsley VE (1926). "Dimethylstibine cyanide, an analogue of cacodyl cyanide". Proc. R. Soc. Lond. A. 110 (755): 534–537. Bibcode:1926RSPSA.110..534M. doi:10.1098/rspa.1926.0031.
  5. ^ Seyferth D (2001). "Cadet's Fuming Arsenical Liquid and the Cacodyl Compounds of Bunsen". Organometallics. 20 (8): 1488–1498. doi:10.1021/om0101947.
  6. ^ a b Organic Arsenical Compounds. 1923.
  7. ^ "Scientific Worthies" (PDF). 28 April 1881. Archived (PDF) from the original on 2021-12-12.
  8. ^ Curry R (11 May 2015). "Cacodyl Cyanide Chemistry Catastrophe - Professor Bunsen's Aphasia, Black Tongue, Blind Eye & Nearly Fatal Poisoning". Lateral Science.
  9. ^ Freemantle M (26 January 2019). "Cacodyl".
  10. ^ "ЗАБЫТАЯ ХИМИЧЕСКАЯ ВОЙНА 1915-1918 гг. I. Отравляющие вещества и химическое оружие Первой мировой войны".