- Diphenyl diselenide
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Diphenyl diselenide 
Diphenyl diselenideOther namesPhenyl diselenideIdentifiers CAS number 1666-13-3 
PubChem 15460 ChemSpider 14710 RTECS number JM9152500 Jmol-3D images Image 1 - c1ccc(cc1)[Se][Se]c2ccccc2
- InChI=1S/C12H10Se2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H
Key: YWWZCHLUQSHMCL-UHFFFAOYSA-N
InChI=1/C12H10Se2/c1-3-7-11(8-4-1)13-14-12-9-5-2-6-10-12/h1-10H
Key: YWWZCHLUQSHMCL-UHFFFAOYAK
Properties Molecular formula C12H10Se2 Molar mass 312.13 g mol−1 Appearance Orange powder Density 1.84 g/cm3 Melting point 59-61 °C
Solubility in water Insoluble Solubility in other solvents Dichloromethane Structure Coordination
geometry90° at Se[citation needed]
C2 symmetry[citation needed]Dipole moment 0 D Hazards R-phrases R23/25 R33 R50/53 S-phrases S20/21 S28 S45 S60 S61 Main hazards Toxic Related compounds Related compounds Ph2S2,
C6H5SeH
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Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa)Infobox 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]
It has a centrosymmetric structure, with an Se-Se bond length of 2.29 A.[2]
Reactions
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−
N-Phenylselenophtalimide (N-PSP) can be used if PhSeCl is too strong and diphenyl diselenide is too weak or wasteful.[6]
Safety
Organoselenium compounds are toxic.
References
- ^ Reich, H. J.; Cohen, M. L.; Clark, P. S. (1979), "Reagents for Synthesis of Organoselenium Compounds: Diphenyl Diselenide and Benzeneselenenyl Chloride", Org. Synth. 59: 141, http://www.orgsyn.org/orgsyn/orgsyn/prepContent.asp?prep=CV6P0533; Coll. Vol. 6: 533
- ^ . doi:10.1107/S0365110X52001349.
- ^ . doi:10.1021/ja027882h.
- ^ Lerchner, A.; Carreira, E. M. J. Am. Chem. Soc. 2002, 124, 14826
- ^ Preparation of α,β-Unsaturated Carbonyl Compounds and Nitriles by Selenoxide Elimination. Reich, H. J.; Wollowitz, S. Organic Reactions 1993, 44, 1.
- ^ Barrero, Alejandro F.; E. J. Alvarez-Manzaneda, R. Chahboun, M. Corttés, V. Armstrong (1999). "Synthesis and antitumor activity of puupehedione and related compounds". Tetrahedron 55 (52): 15181–15208. doi:10.1016/S0040-4020(99)00992-8.
Categories:- Organoselenium compounds
- Aromatic compounds
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