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

organic compound In chemistry, organic compounds are generally any chemical compounds that contain carbon-hydrogen or carbon-carbon bonds. Due to carbon's ability to catenate (form chains with other carbon atoms), millions of organic compounds are known. Th ...

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 called carbolic acid) is an aromatic organic compound with the molecular formula . It is a white crystalline solid that is volatile. The molecule consists of a phenyl group () bonded to a hydroxy group (). Mildly acidic, it r ...

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 pso ...

, 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 elements, chiefly hydrogen, sulfur, oxygen, and nitrogen. Coal is formed when ...

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

and

cresol Cresols (also hydroxytoluene 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 categorized as methylphenol ...

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

sulfonation Aromatic sulfonation is an organic reaction in which a hydrogen atom on an arene is replaced by a sulfonic acid functional group in an electrophilic aromatic substitution. Aryl sulfonic acids are used as detergents, dye, and drugs. Stoichiometry a ...

toluene Toluene (), also known as toluol (), is a substituted aromatic hydrocarbon. It is a colorless, water-insoluble liquid with the smell associated with paint thinners. It is a mono-substituted benzene derivative, consisting of a methyl group (CH3) ...

: :CH₃C₆H₅ + H₂SO₄ → CH₃C₆H₄SO₃H + H₂O

Basic BASIC (Beginners' All-purpose Symbolic Instruction Code) is a family of general-purpose, high-level programming languages designed for ease of use. The original version was created by John G. Kemeny and Thomas E. Kurtz at Dartmouth College ...

hydrolysis of the sulfonate 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 CH3CH=CH2. 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 petrol ...

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 w ...

Applications

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

antioxidant Antioxidants are compounds that inhibit oxidation, a chemical reaction that can produce free radicals. This can lead to polymerization and other chain reactions. They are frequently added to industrial products, such as fuels and lubrica ...

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 oxidat ...

(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 Fermentation is a metabolic process that produces chemical changes in organic substrates through the action of enzymes. In biochemistry, it is narrowly defined as the extraction of energy from carbohydrates in the absence of oxygen. In food ...

protein Proteins are large biomolecules and macromolecules that comprise one or more long chains of amino acid residues. Proteins perform a vast array of functions within organisms, including catalysing metabolic reactions, DNA replication, res ...

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 digestive system in tetrapods. Water is absorbed here and the remaining waste material is stored in the rectum as feces before bein ...

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

sweat Perspiration, also known as sweating, is the production of fluids secreted by the sweat glands in the skin of mammals. Two types of sweat glands can be found in humans: eccrine glands and apocrine glands. The eccrine sweat glands are distrib ...

that attracts female

mosquito Mosquitoes (or mosquitos) are members of a group of almost 3,600 species of small flies within the family Culicidae (from the Latin ''culex'' meaning " gnat"). The word "mosquito" (formed by ''mosca'' and diminutive ''-ito'') is Spanish for "li ...

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

tobacco smoke Tobacco smoke is a sooty aerosol produced by the incomplete combustion of tobacco during the smoking of cigarettes and other tobacco products. Temperatures in burning cigarettes range from about 400 °C between puffs to about 900 °C d ...

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, )''The Oxford Dictionary and Thesaurus: American edition'', published 1996 by Oxford University Press; p. 984 is a periodic condition in bull (male) elephants characterized by aggressive behavior and accompanied ...

in male

elephant Elephants are the largest existing land animals. Three living species are currently recognised: the African bush elephant, the African forest elephant, and the Asian elephant. They are the only surviving members of the family Elephantida ...

s. It is one of the very few compounds to attract the

orchid bee The tribe Euglossini, in the subfamily Apinae, commonly known as orchid bees or euglossine bees, are the only group of corbiculate bees whose non-parasitic members do not all possess eusocial behavior. Description Most of the tribe's species ...

'' 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 million yea ...

urine during

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

that can elicit the Flehmen response.

References

{{DEFAULTSORT:Cresol, p- Cresols Alkylphenols