P-Cresol Explained

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:[1]

CH3C6H5 + H2SO4 → CH3C6H4SO3H + H2OBasic hydrolysis of the sulfonate salt gives the sodium salt of the cresol:

CH3C6H4SO3H + 2 NaOH → CH3C6H4OH + Na2SO3 + H2OOther 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.[2] [3]

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,[4] and is a component of human sweat that attracts female mosquitoes.[5] [6]

p-Cresol is a constituent of tobacco smoke.[7]

In other species

p-Cresol is a major component in pig odor.[8] Temporal glands secretion examination showed the presence of phenol and p-cresol during musth in male elephants.[9] [10] 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.[11] p-Cresol is a component found in horse urine during estrus that can elicit the Flehmen response.[12]

Notes and References

  1. 10.15227/orgsyn.003.0037. p-Cresol. Organic Syntheses. 3. 37. 1923. W. W. Hartman.
  2. Web site: April 2005 . meta- and para-Cresols . dead . https://web.archive.org/web/20171208161609/https://inchem.org/documents/sids/sids/m-p-cresols.pdf . 2017-12-08 . 2022-11-04 . International Programme on Chemical Safety (IPCS INCHEM).
  3. Web site: p-Cresol - Hazardous Agents . 2022-11-04 . Haz-Map

    Information on Hazardous Chemicals and Occupational Diseases

    .
  4. Hamer HM, De Preter V, Windey K, Verbeke K . Functional analysis of colonic bacterial metabolism: relevant to health? . American Journal of Physiology. Gastrointestinal and Liver Physiology . 302 . 1 . G1-9 . January 2012 . 22016433 . 3345969 . 10.1152/ajpgi.00048.2011.
  5. Hallem EA, Nicole Fox A, Zwiebel LJ, Carlson JR . Olfaction: mosquito receptor for human-sweat odorant . Nature . 427 . 6971 . 212–213 . January 2004 . 14724626 . 10.1038/427212a . 2004Natur.427..212H. 4419658 .
  6. Linley JR . Laboratory tests of the effects of p-cresol and 4-methylcyclohexanol on oviposition by three species of Toxorhynchites mosquitoes . Medical and Veterinary Entomology . 3 . 4 . 347–52 . October 1989 . 2577519 . 10.1111/j.1365-2915.1989.tb00241.x. 1641506 .
  7. Talhout R, Schulz T, Florek E, van Benthem J, Wester P, Opperhuizen A . Hazardous compounds in tobacco smoke . International Journal of Environmental Research and Public Health . 8 . 2 . 613–28 . February 2011 . 21556207 . 3084482 . 10.3390/ijerph8020613. free .
  8. Web site: Brendan . Borrell . 5 March 2009 . Why study pig odor? . Scientific American . 9 March 2009 . 20 March 2021 . https://web.archive.org/web/20210320042122/https://www.scientificamerican.com/article/why-study-pig-odor/ . live .
  9. Rasmussen LE, Perrin TE . Physiological correlates of musth: lipid metabolites and chemical composition of exudates . Physiology & Behavior . 67 . 4 . 539–49 . October 1999 . 10549891 . 10.1016/S0031-9384(99)00114-6. 21368454 .
  10. Musth in elephants . Deepa . Ananth . vanc. Zoos' Print Journal . 15 . 5 . 259–62 . 10.11609/jott.zpj.14.4.259-62. May 2000 . free.
  11. Williams NH, Whitten WM . June 1983 . Orchid Floral Fragrances and Male Euglossine Bees: Methods and Advances in the Last Sesquidecade . Biological Bulletin . 164 . 3 . 355–95 . 1541248 . 10.2307/1541248 . 2021-11-10 . 2020-06-05 . https://web.archive.org/web/20200605121541/https://www.biodiversitylibrary.org/part/35261 . live .
  12. Būda V, Mozūraitis R, Kutra J, Borg-Karlson AK . p-Cresol: a sex pheromone component identified from the estrous urine of mares . Journal of Chemical Ecology . 38 . 7 . 811–3 . July 2012 . 22592336 . 10.1007/s10886-012-0138-2. 14558317 .

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