Phenols

In organic chemistry, phenols, sometimes called phenolics, are a class of chemical compounds consisting of a hydroxyl group (-O H) attached to an aromatic hydrocarbon group. The simplest of the class is phenol (C₆H₅OH).

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 tightly coupling with the oxygen and a relatively loose bond between the oxygen and hydrogen. The acidity of the hydroxyl group in phenols is commonly intermediate between that of aliphatic alcohols and carboxylic acids. Loss of a positive hydrogen ion (H+) from the hydroxyl group of a phenol forms a negative phenolate ion.

Some phenols are germicidal and are used in formulating disinfectants. Others possess estrogenic or endocrine disrupting activity.

Phenolic compounds

Phenol, the parent compound, used as an disinfectant and for chemical synthesis.
Salicylic acid, a plant hormone and analgesic, antipyretic, and anti-inflammatory drug, precursor compound to Aspirin.
Propofol, a short-acting intravenous anesthetic agent.
Cannabinoids, the active constituents of cannabis.
Psilocin, a hallucinogenic alkaloid of Psilocybe mushrooms.
Capsaicin, the pungent compound of chilli peppers.
Tyrosine, an amino acid.
The neurotransmitters serotonin, dopamine, adrenaline, and noradrenaline.
L-DOPA, a drug to treat Parkinson's disease.
Eugenol, the main constituent of the essential oil of clove.
Chavibetol from betel.
Estradiol and other estrogens.
Diethylstilbestrol, a synthetic estrogen with a stilbene structure.
Methyl salicylate, the major constituent of the essental oil of wintergreen.
Guaiacol (2-methoxyphenol) from roasted coffee, whisky, and smoke that has a smokey flavor.
Raspberry ketone a compound with an intense raspberry smell.
Gallic acid, found in gallnuts.
Polyphenols like the flavonoids and tannins.
Orthophenyl phenol, a fungicide used for waxing citrus fruits.
Picric acid, an explosive material.
The pH indicators phenolphthalein, phenol red, bromothymol blue, thymolphthalein, and bromophenol blue.
4-Nonylphenol, a breakdown product of detergents and nonoxynol-9.
Thymol (2-Isopropyl-5-methyl phenol), an antiseptic that is used in mouthwashes.
Cresols from coal tar and creosote.
BHT (butylated hydroxytoluene), a fat-soluble antioxidant and food additive.
... and many more.