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Halogenation of benzene where X is the halogen, catalyst represents the catalyst (if needed) and HX represents the protonated base. A few types of aromatic compounds, such as phenol, will react without a catalyst, but for typical benzene derivatives with less reactive substrates, a Lewis acid is required as a catalyst.
Remarkably, ketone halogenation also occurs in biological systems, particularly in marine algae, where dibromoacetaldehyde, bromoacetone, 1, l,l -tribromoacetone, and other related compounds have been found. The halogenation is a typical α-substitution reaction that proceeds by acid catalyzed formation of an enol intermediate. [1]: 846
Substituents can generally be divided into two classes regarding electrophilic substitution: activating and deactivating towards the aromatic ring. Activating substituents or activating groups stabilize the cationic intermediate formed during the substitution by donating electrons into the ring system, by either inductive effect or resonance ...
In electrophilic substitution in aromatic compounds, an atom appended to the aromatic ring, usually hydrogen, is replaced by an electrophile.The most important reactions of this type that take place are aromatic nitration, aromatic halogenation, aromatic sulfonation and acylation and alkylating Friedel-Crafts reactions.
The Sandmeyer reaction can also be used to convert aryl amines to phenols proceeding through the formation of an aryl diazonium salt. In the presence of copper catalyst, such as copper(I) oxide , and an excess of copper(II) nitrate , this reaction takes place readily at room temperature neutral water. [ 28 ]
Caffenol is a photographic alternative process whereby phenols, sodium carbonate and optionally vitamin C are used in aqueous solution as a film and print photographic developer. [1] [2] Other basic (as opposed to acidic) chemicals can be used in place of sodium carbonate; however, sodium carbonate is the most common. [1]
The content of phenols in rosé wine (82 mg/100 ml) is intermediate between that in red and white wines. In winemaking, the process of maceration or "skin contact" is used to increase the concentration of phenols in wine. Phenolic acids are found in the pulp or juice of the wine and can be commonly found in white wines which usually do not go ...
In chemistry, the haloform reaction (also referred to as the Lieben haloform reaction) is a chemical reaction in which a haloform (CHX 3, where X is a halogen) is produced by the exhaustive halogenation of an acetyl group (R−C(=O)CH 3, where R can be either a hydrogen atom, an alkyl or an aryl group), in the presence of a base.