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Diphenyl diselenide

Diphenyl diselenide
IUPAC name Diphenyl diselenide
Other names Phenyl diselenide
CAS number 1666-13-3
RTECS number JM9152500
Molecular formula C12H10Se2
Molar mass 312.13 g/mol
Appearance Orange powder
Density 1.84 g/cm3
Melting point

59-61 °C

Boiling point


Solubility in water Insoluble
Solubility in other solvents Dichloromethane
90° at Se
C2 symmetry
Dipole moment 0 D
Main hazards Toxic
R-phrases 23/25-33-50/53
S-phrases 20/21-28-45-60-61
Related Compounds
Related compounds Ph2S2,
Except where noted otherwise, data are given for
materials in their standard state
(at 25 °C, 100 kPa)

Infobox disclaimer and references

Diphenyl diselenide is the chemical compound with the formula (C6H5)2Se2, abbreviated Ph2Se2 This orange-coloured solid is the oxidized derivative of benzeneselenol. It is used as a source of the PhSe unit in organic synthesis.

Ph2Se2 is prepared by the oxidation of benzeneselenoate, which is generated via the Grignard reagent:[1]

PhMgBr + Se → PhSeMgBr
2 PhSeMgBr + Br2 → Ph2Se2 + 2 MgBr2

It has a centrosymmetric structure, with an Se-Se bond length of 2.29 A.[2]


Two reactions characteristic of Ph2Se2 are reduction and chlorination:

Ph2Se2 + 2 Na → 2 PhSeNa
Ph2Se2 + Cl2 → 2 PhSeCl

PhSeNa is a useful nucleophile, and can be used to introduce the phenylselenyl group by nucleophilic substitution of alkyl halides, alkyl sulfonates (mesylates or tosylates) or epoxides. The example below was taken from a synthesis of morphine.[3]

PhSeCl is a powerful electrophile, used to introduce PhSe groups by reaction with a variety of nucleophiles, including enolates, enol silyl ethers, Grignard reagents, organolithium reagents, alkenes and amines. In the sequence below (early steps in the synthesis of Strychnofoline), a PhSe group is introduced by reaction of a lactam enolate with PhSeCl.[4] This sequence is a powerful method for the conversion of carbonyl compounds to their α,β-unsaturated analogs.[5]

Diphenyl diselenide itself is also a source of a weakly electrophilic PhSe group in reactions with relatively powerful nucleophiles like Grignard reagents, lithium reagents and ester enolates (but not ketone enolates or weaker nucleophiles). PhSeCl is both more reactive, and more efficient, since with Ph2Se2 half of the selenium is wasted.

Ph2Se2 + Nu- → PhSeNu + PhSe-


Organoselenium compounds are toxic...


  1. ^ Reich, H. J.; Cohen, M. L.; Clark, P. S. "Reagents for Synthesis of Organoselenium Compounds: Diphenyl Diselenide and Benzeneselenenyl Chloride" Organic Syntheses Collective Volume 6, page 533. 1988.
  2. ^ Marsh, R. E. "The Crystal Structure of Diphenyl Diselenide" Acta Crystallographica (1952), volume 5, pages 458-462. doi:10.1107/S0365110X52001349.
  3. ^ Taber, D. F.; Neubert, T. B.; Rheingold, A. L. J. Am. Chem. Soc. 2002, 124, 12416
  4. ^ Lerchner, A.; Carreira, E. M. J. Am. Chem. Soc. 2002, 124, 14826
  5. ^ Preparation of α,β-Unsaturated Carbonyl Compounds and Nitriles by Selenoxide Elimination. Reich, H. J.; Wollowitz, S. Organic Reactions 1993, 44, 1.
This article is licensed under the GNU Free Documentation License. It uses material from the Wikipedia article "Diphenyl_diselenide". A list of authors is available in Wikipedia.
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