p-Cresol

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p-Cresol

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Template:Longitem	1305151
ChEBI	Template:Unbulleted list
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EC Number	Template:Unbulleted list
Template:Longitem	2779
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Template:Longitem	C7H8O
Molar mass	108.13
Appearance	colorless prismatic crystals
Density	1.0347 g/ml
Melting point	Template:Chembox CalcTemperatures
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Solubility in ethanol	miscible
Solubility in diethyl ether	miscible
Vapor pressure	0.11 mmHg (25 °C)
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Template:Longitem	1.5395
NFPA 704 (fire diamond)	Template:NFPA 704 diamond
Flash point	Template:Chembox CalcTemperatures
Explosive limits	1.1%–?
Template:Longitem	o-cresol, m-cresol, phenol

para-Cresol, also 4-methylphenol, is an organic compound 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 and is an isomer of o-cresol and m-cresol.

Production

Together with many other compounds, p-cresol is conventionally extracted from coal tar, the volatilized materials obtained in the roasting of coal to produce coke. This residue contains a few percent by weight of phenol and cresols. Industrially, p-cresol is currently prepared mainly by a two-step route beginning with the sulfonation of toluene:

CH₃C₆H₅ + H₂SO₄ → CH₃C₆H₄SO₃H + H₂O

Basic 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 to give p-cymene, which can be oxidatively dealkylated in a manner similar to the cumene process.

Applications

p-Cresol is consumed mainly in the production of antioxidants, such as butylated hydroxytoluene (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 in the human large intestine. It is excreted in feces and urine, and is a component of human sweat that attracts female mosquitoes.

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 in male elephants. 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 urine during estrus that can elicit the Flehmen response.