Phenylmagnesium bromide

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Phenylmagnesium bromide
OR₂ = ether or THF
General
Systematic name	?
Other names	PMB
Molecular formula	C₆H₅MgBr
SMILES	Br[Mg]c1ccccc1
Molar mass	181.31 g/mol
Appearance	Usually a colorless solution in ether or tetrahydrofuran
CAS number	[100-58-3]
Properties
Density and phase	Solution
Solubility in water	Reacts violently
Basicity (pK_b)	?
Viscosity	? cP at ?°C
Structure
Hazards
MSDS	External MSDS
Main hazards	Highly flammable, corrosive, harmful
NFPA 704
Flash point	?°C
R/S statement	R: R12 R14 R15 R20 R22 R35 R41 S: S16 S26 S30 S33 S36 S37 S39 S43 S45
RTECS number	?
Supplementary data page
Structure and properties	n, ε_r, etc.
Thermodynamic data	Phase behaviour Solid, liquid, gas
Spectral data	UV, IR, NMR, MS
Related compounds
Related compounds	?
Except where noted otherwise, data are given for materials in their standard state (at 25 °C, 100 kPa) Infobox disclaimer and references

Phenylmagnesium bromide, with the simplified formula C₆H₅MgBr, is a a magnesium-containing organometallic compound. It is so commonly used that it is commercially available as an solution in diethyl ether or tetrahydrofuran (THF). Phenylmagnesium bromide is a Grignard reagent. It is often used as a synthetic equivalent for the "Ph^-" phenyl synthon.

1 Preparation and structure
2 Chemistry
3 References
4 External links

[edit] Preparation and structure

Phenylmagnesium bromide can be prepared in the laboratory by treating bromobenzene with magnesium metal, usually in the form of ribbon. A polar solvent is required to solvate the magnesium portion of the molecule, hence the use of ether or THF. Protic solvents such as alcohols and water react with phenylmagnesium bromide to give benzene, and halogenated solvents are also incompatible with the synthesis. A small amount of iodine may be used to activate the magnesium by removing the oxide surface.

Although in organic synthesis it is convenient to represent this species as C₆H₅MgBr, the molecule is more complex as shown in the figure. The compound invariably forms an adduct with two OR₂ ligands from the ether or THF solvent. Thus the Mg is tetrahedral and obeys the octet rule.

[edit] Chemistry

Phenylmagnesium bromide is a strong nucleophile as well as a strong base. It can abstract many labile protons, thus the substrate must be protected where necessary. It often adds to carbonyls, which are electron-deficient, such as in the laboratory synthesis of benzoic acid and triphenylmethanol.