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Phenyllithium is an organometallic agent with the empirical formula C 6 H 5 Li. It is most commonly used as a metalating agent in organic syntheses and a substitute for Grignard reagents for introducing phenyl groups in organic syntheses. [ 3 ]
A general acyl group (blue) in a ketone (top left), as an acylium cation (top centre), as an acyl radical (top right), an aldehyde (bottom left), ester (bottom centre) or amide (bottom right).
Those with five organic substituents are rare, although P(C 6 H 5) 5 is known, being derived from P(C 6 H 5) 4 + by reaction with phenyllithium. [citation needed] Phosphorus ylides are unsaturated phosphoranes, known as Wittig reagents, e.g. CH 2 P(C 6 H 5) 3. These compounds feature tetrahedral phosphorus(V) and are considered relatives of ...
Phenyl groups are usually introduced using reagents that behave as sources of the phenyl anion or the phenyl cation. Representative reagents include phenyllithium (C 6 H 5 Li) and phenylmagnesium bromide (C 6 H 5 MgBr). Electrophiles are attacked by benzene to give phenyl derivatives: + + + +
pKa values for acetic, chloroacetic, dichloroacetic and trichloroacetic acids. Inductive effects and mesomeric effects affect the pK a values. A simple example is provided by the effect of replacing the hydrogen atoms in acetic acid by the more electronegative chlorine atom.
tert-Butyllithium, with three weakly electron donating alkyl groups, is the strongest base commercially available (pKa = 53). As a result, the acidic protons on −OH, −NH and −SH are often protected in the presence of organolithium reagents.
The erythro betaine can be converted to the threo betaine using phenyllithium at low temperature. [18] This modification affords the E-alkene. The Schlosser variant of the Wittig reaction. Allylic alcohols can be prepared by reaction of the betaine ylide with a second aldehyde. [19] For example: An example of the Schlosser variant of the Wittig ...
Here, phenyllithium 1 attacks the carbonyl group of DMF 2, giving tetrahedral intermediate 3. Because the dimethylamide anion is a poor leaving group, the intermediate does not collapse and another nucleophilic addition does not occur. Upon acidic workup, the alkoxide is protonated to give 4, then the amine is protonated to give 5.