Benzeneselenol

Benzeneselenol

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Names
IUPAC name benzeneselenol
Other names Selenaphenol, selenophenol, phenylselenol
Identifiers
CAS Number	645-96-5 Y
ChemSpider	62734 Y
Jmol 3D model	Interactive image
PubChem	69530
InChI InChI=1S/C6H6Se/c7-6-4-2-1-3-5-6/h1-5,7H Y Key: WDODWFPDZYSKIA-UHFFFAOYSA-N Y InChI=1/C6H6Se/c7-6-4-2-1-3-5-6/h1-5,7H Key: WDODWFPDZYSKIA-UHFFFAOYAD
SMILES [SeH]c1ccccc1
Properties
Chemical formula	C6H6Se
Molar mass	157.07 g/mol
Appearance	colorless liquid
Density	1.479 g/cm3
Boiling point	71 to 72 °C (160 to 162 °F; 344 to 345 K) (18 mm Hg)
Solubility in water	slightly
Solubility in other solvents	most organic solvents
Refractive index (nD)	1.616
Structure
Dipole moment	1.1 D
Vapor pressure	{{{value}}}
Related compounds
Related compounds	Thiophenol, Hydrogen selenide, Diphenyl diselenide
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Infobox references

Benzeneselenol is the organoselenium compound with the formula C₆H₅SeH, often abbreviated PhSeH. It is the selenium analog of the simple aromatic alcohol phenol, and the related thiol thiophenol. This colourless, intensely malodorous compound is a useful reagent in organic synthesis.

Synthesis and basic properties

Benzeneselenol is prepared via the reaction of phenylmagnesium bromide and selenium:

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More so than thiophenol, benzeneselenol is easily oxidized by air. The product is diphenyl diselenide as shown in this idealized equation:

4 PhSeH + O₂ → 2 PhSeSePh + 2 H₂O

The presence of the diselenide is indicated by a yellow coloration in most samples of PhSeH. The diselenide can be converted back to the selenol by reduction followed by acidification of the resulting PhSe⁻.

PhSeH is approximately seven times more acidic than the related thiophenol. Both compounds dissolve in water upon the addition of base.

In organic synthesis benzeneselenol is converted to its conjugate base PhSe⁻, a potent nucleophile.

History

Benzeneselenol was first reported in 1888 by the reaction of benzene with selenium tetrachloride (SeCl₄) in the presence of aluminium trichloride (AlCl₃).

Safety

The compound is intensely malodorous and, like other organoselenium compounds, toxic.