Tetraiodoethylene

Tetraiodoethylene, TIE or diiodoform, is an organoiodine compound with the chemical formula C₂I₄. Its structure is I₂C=CI₂. It is an odourless yellow crystalline solid that is soluble in benzene and chloroform, and insoluble in water.^[2] It has been used as an antiseptic and a component in pesticide and fungicide formulations.^[5][6] It is the periodinated analogue of ethylene. It is a decomposition product of carbon tetraiodide and diiodoacetylene.^[7]

Tetraiodoethylene

Names
IUPAC name Tetraiodoethene
Other names Periodoethylene Periodoethene Diiodoform Ethylene tetraiodide
Identifiers
CAS Number	513-92-8
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL3182626
ChemSpider	10126
ECHA InfoCard	100.007.434
EC Number	208-176-2
PubChem CID	10568
UNII	K9R00J32Z7
CompTox Dashboard (EPA)	DTXSID4042462
InChI InChI=1S/C2I4/c3-1(4)2(5)6 Key: ZGQURDGVBSSDNF-UHFFFAOYSA-N
SMILES C(=C(I)I)(I)I
Properties
Chemical formula	C2I4
Molar mass	531.640 g·mol−1
Appearance	yellow crystalline solid
Odor	Odourless[1]
Density	2.98 g/cm3
Melting point	187–192 °C (369–378 °F; 460–465 K)[2]
Boiling point	Sublimates[2]
Solubility in water	Insoluble
Solubility	Soluble in chloroform, carbon disulphide, benzene and toluene,[3] sparingly soluble in ether[3]
Hazards
GHS labelling:[4]
Pictograms
Signal word	Warning
Hazard statements	H302, H312, H315, H319, H332, H335
Precautionary statements	P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P304+P340, P305+P351+P338, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P403+P233, P405, P501
Related compounds
Related compounds	Ethylene Iodoethylene 1,1-Diiodoethylene 1,2-Diiodoethylene Triiodoethylene Tetrafluoroethylene Tetrachloroethylene Tetrabromoethylene Tetraiodomethane Hexaiodoethane
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa). Infobox references

Tetraiodoethylene reacts with ethylamine to give ethylamine di-tetraiodoethylene, CH₃CH₂NH₂·(C₂I₄)₂, and ethylamine tetraiodoethylene, CH₃CH₂NH₂·C₂I₄.^[8] Tetraiodoethylene and iodine pentafluoride yield iodopentafluoroethane.^[9]

Tetraiodoethylene turns brown and emits a characteristic odour due to decomposition when exposed to light.^[10]

History

Tetraiodoethylene was discovered by Baeyer in 1885.^[7] It was proposed as an antiseptic under the name Diiodoform, in 1893 by M. L. Maquenne and Taine.^[10] It was an alternative to iodoform^[10] which has a strong and persistent odour that caused difficulties for physicians in private practices.^[11]

Synthesis

Tetraiodoethylene can be made by the iodination of calcium carbide:^[1]

CaC₂ + 3 I₂ → C₂I₄ + CaI₂

Diiodoacetylene is a byproduct of the reaction which can later be iodinated to TIE.^[1]

The action of aqueous solution of potassium hydroxide and iodine on barium carbide in chloroform or benzene can also give TIE.^[10] Another synthesis involves mixing separate solutions of diiodoacetylene and iodine in carbon disulphide. Tetraiodoethylene would be left as a residue after carbon disulphide was evaporated.^[10]

See also

• 1,2-Diiodoethylene
• Triiodoethylene
• Tetrafluoroethylene
• Tetrachloroethylene
• Tetrabromoethylene