メソトライアリル置換スマーガディリン:容易な芳香性の切り替え
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Treating arylamines with nitrous acid gives aryldiazonium salts that are effective substrates in nucleophilic aromatic substitution reactions. The diazonio group in these salts can be easily displaced by different nucleophiles, yielding a wide variety of substituted benzenes. The leaving group departs as nitrogen gas, and this easy elimination is the driving force for the substitution reaction.
In the Sandmeyer reaction, for example, the diazonio group is replaced by a chloro, bromo,...
Nucleophilic substitution in aromatic compounds is feasible in substrates bearing strong electron-withdrawing substituents positioned ortho or para to the leaving group. The reaction proceeds via two steps: the addition of the nucleophile and the elimination of the leaving group.
The reaction begins with an attack of the nucleophile on the carbon that holds the leaving group. This results in the delocalization of the π electrons over the ring carbons. The resonance interaction between...
In an electrophilic aromatic substitution reaction, an electrophile substitutes for a hydrogen of an aromatic compound.
Many functional groups can be added to aromatic compounds by these reactions. All electrophilic aromatic substitution reactions occur via a two-step mechanism. In the first step, the π system of the aromatic ring reacts with an electrophile, forming an arenium ion, which is resonance-stabilized. It is often referred to as a sigma complex because the electrophile forms a...
Bromination and chlorination of aromatic rings by electrophilic aromatic substitution reactions are easily achieved, but fluorination and iodination are difficult to achieve. Fluorine is so reactive that its reaction with benzene is difficult to control, resulting in poor yields of monofluoroaromatic products. To address this, Selectfluor reagent is used as a fluorine source in which a fluorine atom is bonded to a positively charged nitrogen.
Unlike fluorine, iodine is highly unreactive for...
The nitration of benzene is an example of an electrophilic aromatic substitution reaction. It involves the formation of a very powerful electrophile, the nitronium ion, which is linear in shape. The reaction occurs through the interaction of two strong acids, sulfuric and nitric acid.
Sulfuric acid is stronger and protonates the nitric acid on the hydroxyl group, followed by loss of water molecule, generating the nitronium ion.
The nitronium ion acts as an electrophile that reacts with...
Sulfonation of benzene is a reaction wherein benzene is treated with fuming sulfuric acid at room temperature to produce benzenesulfonic acid. Fuming sulfuric acid is a mixture of sulfur trioxide and concentrated sulfuric acid.
The active electrophile is either neutral sulfur trioxide or protonated sulfur trioxide ion, depending on the reaction conditions. One of the mechanisms involves neutral sulfur trioxide acting as an electrophile, which reacts with the π electron cloud of nucleophilic...

