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A carbanion is one of several reactive intermediates in organic chemistry. In organic synthesis, organolithium reagents and Grignard reagents are commonly treated and referred to as "carbanions." This is a convenient approximation, although these species are generally clusters or complexes containing highly polar, but still covalent bonds metal ...
A carbocation is an ion with a positively charged carbon atom. Among the simplest examples are the methenium CH + 3, ... Carbanion; Carbene; Oxocarbenium; References
The 2-Norbornyl cation is one of the best characterized carbonium ion. It is the prototype for non-classical ions. As indicated first by low-temperature NMR spectroscopy and confirmed by X-ray crystallography, [1] it has a symmetric structure with an RCH 2 + group bonded to an alkene group, stabilized by a bicyclic structure.
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 ]
This forms a carbocation intermediate, and the X then bonds to the positive carbon that is available, as in the following two-step reaction. [4] CH 2 CH 2 + HX → CH 2 CH + 3 + X − CH 2 CH + 3 + X − → CH 2 XCH 3. Similarly, in an H 2 O addition reaction, the pi bond of an alkene acts as a nucleophile and bonds with the proton of an [H 3 ...
Reactive intermediates have several features in common: low concentration with respect to reaction substrate and final reaction product; with the exception of carbanions, these intermediates do not obey the lewis octet rule, hence the high reactivity
Substitution reactions in organic chemistry are classified either as electrophilic or nucleophilic depending upon the reagent involved, whether a reactive intermediate involved in the reaction is a carbocation, a carbanion or a free radical, and whether the substrate is aliphatic or aromatic. Detailed understanding of a reaction type helps to ...
Historically, nonclassical ions were invoked to explain unusually fast solvolyses of steroidal, norbornyl, and cyclopropyl halides. [4] [5] Explanations for these rates was once controversial. [6] The 2-norbornyl cation is one of the best characterized carbonium ions: C 7 H 10 + H + → C 7 H + 11. In fact, it has emerged as the prototype for ...