Benzeneselenol

Benzeneselenol, also known as selenophenol, is the organoselenium compound with the formula C6H5SeH, often abbreviated PhSeH. It is the selenium analog of phenol. This colourless, intensely malodorous compound is a useful reagent in organic synthesis.[1]

Benzeneselenol
Names
IUPAC name
benzeneselenol
Other names
Selenaphenol,
selenophenol,
phenylselenol
Identifiers
3D model (JSmol)
ChemSpider
ECHA InfoCard 100.010.417
EC Number
  • 211-457-2
  • 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
  • [SeH]c1ccccc1
Properties
C6H6Se
Molar mass 157.07 g/mol
Appearance colorless liquid
Odor extremely foul yet characteristic
Density 1.479 g/cm3
Boiling point 71 to 72 °C (160 to 162 °F; 344 to 345 K) (18 mm Hg)
slightly
Solubility in other solvents most organic solvents
1.616
Structure
1.1 D
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
 toxic
GHS labelling:
Danger
H301, H331, H373, H410
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).
Y verify (what is YN ?)
Infobox references

Synthesis

Benzeneselenol is prepared by the reaction of phenylmagnesium bromide and selenium:[2]

PhMgBr + Se → PhSeMgBr
PhSeMgBr + HCl → PhSeH + MgBrCl

Reactions

More so than thiophenol, benzeneselenol is easily oxidized by air. The facility of this reaction reflects the weakness of the Se-H bond. The product is diphenyl diselenide as shown in this idealized equation:

4 PhSeH + O2 → 2 PhSeSePh + 2 H2O

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

PhSeH is acidic with a pKa of 5.9. Thus at neutral pH, it is mostly ionized:

PhSeH → PhSe− + H+

It is approximately seven times more acidic than the related thiophenol. Both compounds dissolve in water upon the addition of base. The conjugate base is PhSe−, a potent nucleophile.[1]

History

Benzeneselenol was first reported in 1888 by the reaction of benzene with selenium tetrachloride (SeCl4) in the presence of aluminium trichloride (AlCl3).[3][4]

Safety

The compound is intensely malodorous[5] and, like other organoselenium compounds, toxic.

References
  1. Sonoda, Noboru; Ogawa, Akiya; Recupero, Francesco (2005). "Benzeneselenol". Encyclopedia of Reagents for Organic Synthesis. doi:10.1002/047084289X.rb018.pub2. ISBN 0471936235.
  2. Foster, D. G. (1944). "Selenophenol". Organic Syntheses. 24: 89. doi:10.15227/orgsyn.024.0089.
  3. Chabrié, M. C. (1888). "Premiers essais de synthèse de composés organiques séléniés dans la série aromatique". Bulletin de la Société Chimique de Paris. 50: 133–137.
  4. Chabrié, M. C. (1890). "Sur la synthèse de quelques composés séléniés dans la série aromatique". Annales de Chimie et de Physique. 6 (20): 202–286.
  5. Lowe, D. (2012-05-15). "Things I wont work with: Selenophenol". In the Pipeline.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.