PHENOLS Mark Angelo N. Siguenza John Robert C. James Daniel Thomas A. Berberabe Charles Jervis T. Sy
sometimes called phenolics , are a class of chemical compounds consisting of a hydroxyl group (-OH) bonded directly to an aromatic hydrocarbon group. The simplest of the class is phenol (C6H5OH).
also known as carbolic acid , is a toxic, white crystalline solid. Its chemical formula is C6H5OH and its structure is that of a hydroxyl group (-OH) bonded to a phenyl ring, making it an aromatic compound.
Although similar to alcohols, phenols have unique properties and are not classified as alcohols (since the hydroxyl group is not bonded to a saturated carbon atom).
They have relatively higher acidities due to the aromatic ring's tight coupling with the oxygen and a relatively loose bond between the oxygen and hydrogen.
SYNTHESIS OF PHENOLS
by an ester rearrangement in the Fries rearrangement
by a rearrangement of N-phenylhydroxylamines in the Bamberger rearrangement
by hydrolysis of phenolic esters or ethers
by reduction of quinones
by replacement of an aromatic amine by an hydroxyl group with water and sodium bisulfide in the Bucherer reaction
by hydrolysis of diazonium salts
by oligomerisation with formaldehyde + base catalysed reaction with epichlorohydrine to epoxi resin components
by reaction with acetone/ketones to e.g. Bisphenol A, an important monomer for resins, e.g. polycarbonate(PC), epoxi resins
by a rearrangement reaction of dienones in the dienone phenol rearrangement
REACTION OF PHENOLS
Esterfication reactions and ether formation
Electrophilic aromatic substitutions as the hydroxyl group is activating, for example synthesis of calixarenes.
Reaction of naphtols and hydrazines and sodium bisulfite in the Bucherer carbazole synthesis.
Oxidative cleavage, for instance cleavage of 1,2-dihydroxybenzene to the monomethylester of 2,4 hexadienedioic acid with oxygen, copper chloride in pyridine.
Oxidative de-aromatization to quinones also known as the Teuber reaction. Oxidizing reagents are Fremy's salt and oxone. In reaction depicted below 3,4,5-trimethylphenol reacts with singlet oxygen generated from oxone/sodium carbonate in an acetonitrile/water mixture to a para-peroxyquinole. This hydroperoxide is reduced to the quinole with sodium thiosulfate.
Phenols are oxidized to phediols in the Elbs persulfate oxidation.
Phenolate anions (deriving from phenols by the loss of H+) can act as ligands towards metal cations
Phenols are found in the natural world, especially in the plant kingdom. In some cases phenols are present in vegetative foliage to discourage herbivory, such as in the case of Western poison oak.
chemical engineering processes
MEDICINALS a plant hormone used for its analgesic, antipyretic, and anti-inflammatory properties, also a precursor compound to Aspirin Salicylic acid a short-acting intravenous anesthetic agent Propofol the major constituent of the essential oil of wintergreen Methyl salicylate a dopamine prodrug L-DOPA a synthetic estrogen with a stilbene structure Diethylstilbestrol the active constituents of cannabis Cannabinoids