In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group bonded directly to an aromatic hydrocarbon group. The simplest of the class is phenol, which is also called carbolic acid C 6H 5OH, phenolic compounds are classified as simple phenols or polyphenols based on the number of phenol units in the molecule. Synonyms are arenols or aryl alcohols, phenolic compounds are synthesized industrially, they also are produced by plants and microorganisms, with variation between and within species. Although similar to alcohols, phenols have unique properties and are not classified as alcohols and they have higher acidities due to the aromatic rings tight coupling with the oxygen and a relatively loose bond between the oxygen and hydrogen. The acidity of the group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids. Phenols can have two or more hydroxy groups bonded to the ring in the same molecule. The simplest examples are the three benzenediols, each having two groups on a benzene ring. Organisms that synthesize phenolic compounds do so in response to pressures such as pathogen and insect attack, UV radiation. As they are present in food consumed in human diets and in used in traditional medicine of several cultures, their role in human health. Some phenols are germicidal and are used in formulating disinfectants, others possess estrogenic or endocrine disrupting activity. They can also be classified on the basis of their number of phenol groups and they can therefore be called simple phenols or monophenols, with only one phenolic group, or di-, tri- and oligophenols, with two, three or several phenolic groups respectively. The phenolic unit can be found dimerized or further polymerized, creating a new class of polyphenol, two natural phenols from two different categories, for instance a flavonoid and a lignan, can combine to form a hybrid class like the flavonolignans. Nomenclature of polymers, Plants in the genus Humulus and Cannabis produce terpenophenolic metabolites, phenolic lipids are long aliphatic chains bonded to a phenolic moiety. The majority of compounds are solubles molecules but the smaller molecules can be volatiles. Many natural phenols present chirality within their molecule, an example of such molecules is catechin. Cavicularin is an unusual macrocycle because it was the first compound isolated from nature displaying optical activity due to the presence of planar chirality, natural phenols chemically interact with many other substances. Stacking, a property of molecules with aromaticity, is seen occurring between phenolic molecules. When studied in mass spectrometry, phenols easily form adduct ions with halogens and they can also interact with the food matrices or with different forms of silica
Phenol - the simplest of the phenols.
Neutral phenol substructure "shape". An image of a computed electrostatic surface of neutral phenol, showing neutral regions in green, electronegative areas in orange-red, and the electropositive phenolic proton in blue.