Benzeneselenol
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| Benzeneselenol | |
|---|---|
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| General | |
| Systematic name | benzeneselenol |
| Other names | Selenaphenol, selenophenol, phenylselenol |
| Molecular formula | C6H6Se |
| SMILES | ? |
| Molar mass | 157.07 g/mol |
| Appearance | colourless liquid |
| CAS number | [645-96-5] |
| Properties | |
| Density and phase | 1.479 g/cm3 |
| Solubility in water | slightly |
| Other solvents | most organic solvents |
| Melting point | ? °C |
| Boiling point | 71-72 °C (18 mm Hg) |
| Basicity (pKa) | 5.9 |
| Viscosity | ? cP at ? °C |
| Structure | |
| Coordination geometry |
? |
| Crystal structure | |
| Dipole moment | 1.1 D |
| Hazards | |
| MSDS | External MSDS |
| Main hazards | toxic |
| NFPA 704 | |
| Flash point | ? °C |
| R/S statement | R: 23/25-33-50/53 S: 20/21-28-45-60-61 |
| RTECS number | ? |
| Supplementary data page | |
| Structure and properties |
n = 1.616 |
| Thermodynamic data |
Phase behaviour Solid, liquid, gas |
| Spectral data | 1H NMR, δ1.54(SeH) |
| Related compounds | |
| Related compounds | C6H5SH, H2Se, diphenyl diselenide |
| Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references |
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Benzeneselenol is the chemical compound with the formula C6H5SeH, often abbreviated PhSeH. This intensely malodorous liquid is a useful reagent in organic synthesis.
Contents |
[edit] Synthesis and basic properties
PhSeH is prepared via a Grignard reagent:[1]
- PhMgBr + Se → PhSeMgBr
- PhSeMgBr + HCl → PhSeH + MgBrCl
More so that thiophenol, benzeneselenol is easily oxidized by air to give diphenyl diselenide. An idealized equation for this reaction is:
- 2 PhSeH + O → PhSeSePh + H2O
The presence of the diselenide is signaled 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 ca 7x stronger acid than the related thiophenol. Both compounds dissolve in water upon the addition of base.
PhSeH is renowned in organic synthesis as the precursor to its conjugate base PhSe-, a potent nucleophile.[2]
[edit] History
Benzeneselenol was first prepared by the reaction of benzene with SeCl4 in the presence of AlCl3.[3]
[edit] Safety
Organoselenium compounds are toxic.
[edit] References
- ^ Foster, D. G. "Selenophenol" Organic Syntheses, Collected Volume 3, pages 771 (1955)
- ^ Sonoda, N.; Ogawa, A.; Recupero, F. "Benzeneselenol" in Encyclopedia of Reagents for Organic Synthesis (Ed: L. Paquette) 2004, J. Wiley & Sons, New York. DOI: 10.1002/047084289.
- ^ Chabrié, M. Camille “Premiers essays de synthèse de composés organiques séléniés dans la série aromatique” Bull. soc. chim. France, 50, 133 (1888); Ann. chim. phys., (6) 20, 229 (1890)
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