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The benzyl cation or phenylcarbenium ion is the carbocation with formula C 6 H 5 CH + 2; the benzyl anion or phenylmethanide ion is the carbanion with the formula C 6 H 5 CH − 2. None of these species can be formed in significant amounts in the solution phase under normal conditions, but they are useful referents for discussion of reaction ...
A carbocation may be stabilized by resonance by a carbon–carbon double bond or by the lone pair of a heteroatom adjacent to the ionized carbon. The allyl cation CH 2 =CH−CH + 2 and benzyl cation C 6 H 5 −CH + 2 are more stable than most other carbenium ions due to donation of electron density from π systems to the cationic center. [20]
A carbocation is an ion with a positively charged carbon atom. Among the simplest examples are the methenium CH + 3, methanium CH + 5, acylium ions RCO +, and vinyl C ...
In organic chemistry, a carbanion is an anion in which carbon is negatively charged. [1] [failed verification]Formally, a carbanion is the conjugate base of a carbon acid: . R 3 CH + B − → R 3 C − + HB
Benzylic cations of chromium arene complexes are conformationally stable, and undergo only exo attack to afford S N 1 products stereospecifically, with retention of configuration. [1] Propargyl [ 1 ] and oxonium [ 1 ] cations undergo retentive substitution reactions, and even β carbocations react with a significant degree of retention.
In S N 1, allylic and benzylic carbocations are stabilized by delocalizing the positive charge. In S N 2, however, the conjugation between the reaction centre and the adjacent pi system stabilizes the transition state. Because they destabilize the positive charge in the carbocation intermediate, electron-withdrawing groups favor the S N 2
The benzilic acid rearrangement is formally the 1,2-rearrangement of 1,2-diketones to form α-hydroxy–carboxylic acids using a base.This reaction receives its name from the reaction of benzil with potassium hydroxide to form benzilic acid.
a carbocation by heterolysis in a nucleophilic rearrangement or anionotropic rearrangement; a carbanion in an electrophilic rearrangement or cationotropic rearrangement; a free radical by homolysis; a nitrene. The driving force for the actual migration of a substituent in step two of the rearrangement is the formation of a more stable intermediate.