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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.
The chemical complexity of coffee is emerging, especially due to observed physiological effects which cannot be related only to the presence of caffeine. Moreover, coffee contains an exceptionally substantial amount of antioxidants such as chlorogenic acids, hydroxycinnamic acids, caffeine and Maillard reaction products, such as melanoidins. [3]
The overall reaction mechanism, denoted by the Hughes–Ingold mechanistic symbol S E Ar, [3] begins with the aromatic ring attacking the electrophile E + (2a). This step leads to the formation of a positively charged and delocalized cyclohexadienyl cation, also known as an arenium ion, Wheland intermediate, or arene σ-complex (2b).
Halogenation of saturated hydrocarbons is a substitution reaction. The reaction typically involves free radical pathways. The regiochemistry of the halogenation of alkanes is largely determined by the relative weakness of the C–H bonds. This trend is reflected by the faster reaction at tertiary and secondary positions.
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.
Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula C 6 H 5 OH. [5] It is a white crystalline solid that is volatile . The molecule consists of a phenyl group ( −C 6 H 5 ) bonded to a hydroxy group ( −OH ).
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 ]
A tetrachlorophenol is any organochloride of phenol that contains four covalently bonded chlorine atoms. Tetrachlorophenols are produced by electrophilic halogenation of phenol with chlorine. [1] Different isomers of tetrachlorophenol exist according to which ring positions on the phenol contain chlorine atoms. There are three different isomers: