It's a very diverse group of substances that are common in the plant world. Their common feature that brings together in one group is the presence in the molecule of the aromatic (benzene) core, which is one hydroxyl or phenolic, hydroxyl groups. The aromatic nucleus can have two and three hydroxyl groups, which are distinguished by mono-, di-or tri phenol. These are the main reactive hydroxy groups of phenolic compounds. If the molecule contains several aromatic nuclei with the appropriate hydroxy, polyphenols occur. The simplest is the actual phenol, or carbolic acid, a powerful disinfectant. Catechol, resorcinol and hydroquinone refer to bisphenols, to triphenol - pyrogallol, phloroglucinol and oksigidrohinon. The enzymes are able to polymerize phenols, insoluble molecule of tannins, lignin, melanins and humus.
Read more: Phenols