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The ferric chloride test is used to determine the presence of phenols in a given sample or compound (for instance natural phenols in a plant extract). Enols, hydroxamic acids, oximes, and sulfinic acids give positive results as well. [1]
The reaction is attractive for their atom economy because it avoid pre-functionalized starting materials often required in traditional redox-neutral cross-couplings. Oxidative phenol couplings, however, often suffer from over-oxidation, especially since the intended coupled product is more oxidizable (has a lower oxidation potential ) than the ...
Other conditions for iodination include I 2, HIO 3, H 2 SO 4, and N-iodosuccinimide, H 2 SO 4. [1] [2] These conditions are successful for highly deactivated arenes, including nitroaromatics. In a series of studies, the powerful reagent obtained by using a mixture of iodine and potassium iodate dissolved in concentrated sulfuric acid was used.
Phenol esters are active esters, being prone to hydrolysis. Phenols are reactive species toward oxidation. Oxidative cleavage, for instance cleavage of 1,2-dihydroxybenzene to the monomethylester of 2,4 hexadienedioic acid with oxygen, copper chloride in pyridine [4] Oxidative de-aromatization to quinones also known as the Teuber reaction.
In terms of its being an oxidant, iron(III) chloride oxidizes iron powder to form iron(II) chloride via a comproportionation reaction: [10] 2 FeCl 3 + Fe → 3 FeCl 2. A traditional synthesis of anhydrous ferrous chloride is the reduction of FeCl 3 with chlorobenzene: [25] 2 FeCl 3 + C 6 H 5 Cl → 2 FeCl 2 + C 6 H 4 Cl 2 + HCl
At one time, chlorobenzene was the main precursor for the manufacture of phenol: [10] C 6 H 5 Cl + NaOH → C 6 H 5 OH + NaCl. The reaction is known as the Dow process, with the reaction carried out at 350 °C using fused sodium hydroxide without solvent.
The industrial synthesis of 4,4′-biphenol was developed by Allan Hay in the 1960s. [2] [3] As the direct oxidative coupling of phenol gives a mixture of isomers, [4] [5] 4,4′-biphenol is instead prepared from 2,6-di-tert-butylphenol, where para-coupling is the only possibility. [3]
The reaction affords 2- and 4-substituted derivatives. The regiochemistry of halogenation changes in strongly acidic solutions where PhOH 2 ] + predominates. Phenol reacts with dilute nitric acid at room temperature to give a mixture of 2-nitrophenol and 4-nitrophenol while with concentrated nitric acid, additional nitro groups are introduced ...