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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).
In chemistry, halogenation is a chemical reaction which introduces one or more halogens into a chemical compound. Halide -containing compounds are pervasive, making this type of transformation important, e.g. in the production of polymers , drugs . [ 1 ]
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.
C=C + X 2 → X−C−C−X (X represents the halogens bromine or chlorine, and in this case, a solvent could be CH 2 Cl 2 or CCl 4). The product is a vicinal dihalide. This type of reaction is a halogenation and an electrophilic addition.
C 3 H 5-Cl + NaF → R-F + NaCl This kind of reaction is called Finkelstein reaction . [ 2 ] However, it is also possible, for example, to produce phosphorus fluoride compounds by transhalogenating chlorine, bromine or iodine bound to phosphorus with a metal fluoride.