''para''-Cresol, also 4-methylphenol, is an

organic compound Some chemical authorities define an organic compound as a chemical compound that contains a carbon–hydrogen or carbon–carbon bond; others consider an organic compound to be any chemical compound that contains carbon. For example, carbon-co ...

with the formula CH₃C₆H₄(OH). It is a colourless solid that is widely used intermediate in the production of other chemicals. It is a derivative of

phenol Phenol (also known as carbolic acid, phenolic acid, or benzenol) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile and can catch fire. The molecule consists of a phenyl group () ...

and is an isomer of ''o''-cresol and ''m''-cresol.

Production

Together with many other compounds, ''p''-cresol is conventionally extracted from

coal tar Coal tar is a thick dark liquid which is a by-product of the production of coke and coal gas from coal. It is a type of creosote. It has both medical and industrial uses. Medicinally it is a topical medication applied to skin to treat psoria ...

, the volatilized materials obtained in the roasting of

coal Coal is a combustible black or brownish-black sedimentary rock, formed as rock strata called coal seams. Coal is mostly carbon with variable amounts of other Chemical element, elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal i ...

to produce coke. This residue contains a few percent by weight of

and

cresol Cresols (also known as hydroxytoluene, toluenol, benzol or cresylic acid) are a group of aromatic organic compounds. They are widely-occurring phenols (sometimes called ''phenolics'') which may be either natural or manufactured. They are also c ...

s. Industrially, ''p''-cresol is currently prepared mainly by a two-step route beginning with the sulfonation of

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon with the chemical formula , often abbreviated as , where Ph stands for the phenyl group. It is a colorless, water Water is an inorganic compound with the c ...

: :CH₃C₆H₅ + H₂SO₄ → CH₃C₆H₄SO₃H + H₂O

Basic Basic or BASIC may refer to: Science and technology * BASIC, a computer programming language * Basic (chemistry), having the properties of a base * Basic access authentication, in HTTP Entertainment * Basic (film), ''Basic'' (film), a 2003 film ...

hydrolysis of the

sulfonate In organosulfur chemistry, a sulfonate is a salt, anion or ester of a sulfonic acid. Its formula is , containing the functional group , where R is typically an organyl group, amino group or a halogen atom. Sulfonates are the conjugate bases of ...

salt gives the sodium salt of the cresol: :CH₃C₆H₄SO₃H + 2 NaOH → CH₃C₆H₄OH + Na₂SO₃ + H₂O Other methods for the production of ''p''-cresol include chlorination of toluene followed by hydrolysis. In the cymene-cresol process, toluene is alkylated with

propene Propylene, also known as propene, is an unsaturated organic compound with the chemical formula . It has one double bond, and is the second simplest member of the alkene class of hydrocarbons. It is a colorless gas with a faint petroleum-like od ...

to give ''p''-cymene, which can be oxidatively dealkylated in a manner similar to the

cumene process The cumene process (cumene-phenol process, Hock process) is an industrial process for synthesizing phenol and acetone from benzene and propylene. The term stems from cumene (isopropyl benzene), the intermediate material during the process. It ...

Applications

''p''-Cresol is consumed mainly in the production of

antioxidant Antioxidants are Chemical compound, compounds that inhibit Redox, oxidation, a chemical reaction that can produce Radical (chemistry), free radicals. Autoxidation leads to degradation of organic compounds, including living matter. Antioxidants ...

s, such as

butylated hydroxytoluene Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. BHT is widely used to prevent free radical-mediated oxidation ...

(BHT). The monoalkylated derivatives undergo coupling to give an extensive family of diphenol antioxidants. These antioxidants are valued because they are relatively low in toxicity and nonstaining.

Natural occurrences

In humans

''p''-Cresol is produced by bacterial fermentation of

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residue (biochemistry), residues. Proteins perform a vast array of functions within organisms, including Enzyme catalysis, catalysing metab ...

in the human

large intestine The large intestine, also known as the large bowel, is the last part of the gastrointestinal tract and of the Digestion, digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces befor ...

. It is excreted in feces and urine, and is a component of human

sweat Perspiration, also known as sweat, is the fluid secreted by sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and Apocrine sweat gland, apocrine glands. The eccrine sweat glands are distribu ...

that attracts female

mosquito Mosquitoes, the Culicidae, are a Family (biology), family of small Diptera, flies consisting of 3,600 species. The word ''mosquito'' (formed by ''Musca (fly), mosca'' and diminutive ''-ito'') is Spanish and Portuguese for ''little fly''. Mos ...

es. ''p''-Cresol is a constituent of tobacco smoke.

In other species

''p''-Cresol is a major component in pig odor. Temporal glands secretion examination showed the presence of phenol and ''p''-cresol during

musth Musth or must (from Persian, ) is a periodic condition in bull (male) elephants characterized by aggressive behavior in animals, aggressive behavior and accompanied by a large rise in reproductive hormones. It has been known in Asian elephan ...

in male

elephant Elephants are the largest living land animals. Three living species are currently recognised: the African bush elephant ('' Loxodonta africana''), the African forest elephant (''L. cyclotis''), and the Asian elephant ('' Elephas maximus ...

s. It is one of the very few compounds to attract the orchid bee '' Euglossa cyanura'' and has been used to capture and study the species. ''p''-Cresol is a component found in

horse The horse (''Equus ferus caballus'') is a domesticated, one-toed, hoofed mammal. It belongs to the taxonomic family Equidae and is one of two extant subspecies of ''Equus ferus''. The horse has evolved over the past 45 to 55 mi ...

urine during

estrus The estrous cycle (, originally ) is a set of recurring physiological changes induced by reproductive hormones in females of mammalian subclass Theria. Estrous cycles start after sexual maturity in females and are interrupted by anestrous phas ...

that can elicit the Flehmen response.

References

{{DEFAULTSORT:Cresol, p- Cresols 4-Tolyl compounds