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All feature three contiguous sp²-hybridized carbon centers and all derive stability from resonance. [6] Each species can be presented by two resonance structures with the charge or unpaired electron distributed at both 1,3 positions. Resonance structure of the allyl anion. The cation is identical, but carries an opposite-sign charge. [7]
In organic chemistry, a vinyl group (abbr. Vi; [1] IUPAC name: ethenyl group [2]) is a functional group with the formula −CH=CH 2. It is the ethylene (IUPAC name: ethene) molecule ( H 2 C=CH 2 ) with one fewer hydrogen atom.
In redox-transmetalation/ligand exchange the ligands of two metal complexes switch places with each other, bonding with the other metal center. The R ligand can be an alkyl, aryl, alkynyl, or allyl group and the X ligand can be a halogen, pseudo-halogen, alkyl, or aryl group. The reaction can proceed by two possible intermediate steps.
A solution of a carbonyl compound is added to a Grignard reagent. (See gallery) An example of a Grignard reaction (R 2 or R 3 could be hydrogen). The Grignard reaction (French:) is an organometallic chemical reaction in which, according to the classical definition, carbon alkyl, allyl, vinyl, or aryl magnesium halides (Grignard reagent) are added to the carbonyl groups of either an aldehyde or ...
Metal acyls also arise from reactions involving acyl chlorides with low-valence metal complexes or by the reaction of organolithium compounds with metal carbonyls. Metal acyls are often described by two resonance structures, one of which emphasizes the basicity of the oxygen center. O-alkylation of metal acyls gives Fischer carbene complexes. [10]
Lithium–halogen exchange is frequently used to prepare vinyl-, aryl- and primary alkyllithium reagents. Vinyl halides usually undergo lithium–halogen exchange with retention of the stereochemistry of the double bond. [2] The presence of alkoxyl or related chelating groups accelerates lithium–halogen exchange. [3]
A phenyl group is the simplest aryl group, here bonded to an "R" group. In organic chemistry, an aryl is any functional group or substituent derived from an aromatic ring, usually an aromatic hydrocarbon, such as phenyl and naphthyl. [1] "Aryl" is used for the sake of abbreviation or generalization, and "Ar" is used as a placeholder for the ...
Alkyl groups that contain one ring have the formula −C n H 2n−1, e.g. cyclopropyl and cyclohexyl. The formula of alkyl radicals are the same as alkyl groups, except the free valence "−" is replaced by the dot "•" and adding "radical" to the name of the alkyl group (e.g. methyl radical •CH 3).