Chemistry:Iodobenzene

Iodobenzene

Names
Preferred IUPAC name Iodobenzene
Other names Phenyl iodide
Identifiers
CAS Number	591-50-4 Y
3D model (JSmol)	Interactive image
ChEMBL	ChEMBL116296 Y
ChemSpider	11087 Y
DrugBank	DB02252 Y
PubChem CID	11575
UNII	9HK5L7YBBR Y
InChI InChI=1S/C6H5I/c7-6-4-2-1-3-5-6/h1-5H Y Key: SNHMUERNLJLMHN-UHFFFAOYSA-N Y InChI=1/C6H5I/c7-6-4-2-1-3-5-6/h1-5H Key: SNHMUERNLJLMHN-UHFFFAOYAQ
SMILES c1ccc(cc1)I
Properties
Chemical formula	C6H5I
Molar mass	204.01 g/mol
Appearance	colorless liquid
Density	1.823 g/cm3
Melting point	−29 °C (−20 °F; 244 K)
Boiling point	188 °C (370 °F; 461 K)
Solubility in water	Insoluble
log P	3
Magnetic susceptibility (χ)	-92.00·10−6 cm3/mol
Viscosity	1.5042 mPa·s (300.65 K)
Hazards
Flash point	74.44 °C (165.99 °F; 347.59 K)
Thermochemistry
Heat capacity (C)	0.779 J/K
Related compounds
Related halobenzenes	Fluorobenzene Chlorobenzene Bromobenzene
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Iodobenzene is the simplest of the iodobenzenes, consisting of a benzene ring substituted with one iodine atom. Its chemical formula is C
6H
5I. It is useful as a synthetic intermediate in organic chemistry. It is a volatile colorless liquid, although aged samples appear yellowish.

Preparation

Iodobenzene is commercially available, or it can be prepared in the laboratory from aniline via the diazotization reaction. In the first step, the amine functional group is diazotized with hydrochloric acid and sodium nitrite. Potassium iodide is added to the resultant phenyldiazonium chloride, causing nitrogen gas to evolve. The product is separated by steam distillation.

Alternatively, it can be produced by refluxing iodine and nitric acid with benzene.

Reactions

Since the C–I bond is weaker than C–Br or C–Cl, iodobenzene is more reactive than bromobenzene or chlorobenzene. Iodobenzene reacts readily with magnesium to form the Grignard reagent, phenylmagnesium iodide. Phenylmagnesium iodide, like the bromide analog, is a synthetic equivalent for the phenyl anion synthon. Iodobenzene reacts with chlorine to give the complex, iodobenzene dichloride, which is used as a solid source of chlorine.

Iodobenzene can also serve as a substrate for the Sonogashira coupling, Heck reaction, and other metal-catalyzed couplings. These reactions proceed via the oxidative addition of iodobenzene.

Further reading

• Gattermann-Wieland, "Laboratory Methods of Organic Chemistry," p. 283. Translated from the twenty-fourth German edition by W. McCartney, The Macmillan Company, New York, 1937.