Diphenyl diselenide

Phenyldiselenid

Yellow crystals

Fixed

1.557 g · cm -3

63 ° C.

202 ° C

Soluble in many organic solvents, insoluble in water

Risk

28 mg · kg -1 ( LD50, mouse, i.v.)

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Diphenyl diselenide is a chemical compound with the formula ( C6H5) 2Se2, abbreviated as Ph2Se2. The orange solid is an oxidized derivative of Selenophenols. It is used in organic synthesis for the introduction of PhSe units.

Representation

Diphenyl diselenide is obtained by reaction of the Grignard reagent phenylmagnesium bromide ( PhMgBr ) heating with selenium under and subsequent oxidation by bromine (Br ):

Properties

Diphenyl diselenide has a centrosymmetric structure with a Se - Se bond length of 2.29 A.

Reactions

Characteristic reactions of diphenyl diselenide are reduction and chlorination:

Phenylnatriumselenid ( PhSeNa ) is a useful nucleophile that can be used to introduce by nucleophilic substitution of an alkyl halide, a mesyl group, a tosyl group or an epoxide, a Phenylselenylgruppe. The following example comes from the morphine synthesis:

Phenylselenchlorid ( PhSeCl ) is a potent electrophile, can be introduced with the phenylselenyl in numerous nucleophiles such as enolates, enol silyl ethers, Grignard reagents, organolithium compounds, alkenes, and amines. In the reaction ( the reaction steps of the synthesis of early strychnofoline ) shown below, a Phenylselenylgruppe is introduced by the reaction of a PhSeCl Lactom enolate. The reaction sequence is an effective method for the conversion of carbonyl compounds into their α, β - unsaturated analogs.

Diphenyldiselenide itself is also a source for the weakly electrophilic Phenylselenylgruppe, however, can only be used in reaction with strong nucleophiles such as Grignard reagents, lithium compounds and enol esters. PhSeCl is both reactive as well as more efficient because with Ph2Se2 half of the selenium is wasted.

N- Phenylselenphtalimid (N- PSP) can be used if PhSeCl is too strong and too wasteful diphenyl diselenide.