Butylated hydroxytoluene

Butylated hydroxytoluene
Skeletal formula of butylated hydroxytoluene
Ball-and-stick model of the butylated hydroxytoluene molecule
Names
IUPAC name
2,6-Bis(1,1-dimethylethyl)-4-methylphenol
Other names
2,6-Di-tert-butyl-4-methylphenol
2,6-Di-tert-butyl-p-cresol (DBPC)
3,5-Di-tert-butyl-4-hydroxytoluene
BHT
E321
AO-29
Avox BHT
Additin RC 7110
Dibutylated hydroxytoluene
4-Methyl-2,6-di-tert-butyl phenol
Identifiers
128-37-0 YesY
ChEBI CHEBI:34247 YesY
ChEMBL ChEMBL146 YesY
ChemSpider 13835296 YesY
EC Number 204-881-4
Jmol 3D model Interactive image
KEGG D02413 YesY
RTECS number GO7875000
UNII 1P9D0Z171K YesY
Properties
C15H24O
Molar mass 220.36 g·mol−1
Appearance White to yellow powder
Odor slight, phenolic
Density 1.048 g/cm3
Melting point 70 °C (158 °F; 343 K) [1]
Boiling point 265 °C (509 °F; 538 K) [1]
1.1 mg/L (20 °C)[2]
Vapor pressure 0.01 mmHg (20°C)[3]
Hazards
Main hazards Flammable
Safety data sheet External MSDS
R-phrases R22-R36-R37-R38
S-phrases S26-S36
NFPA 704
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g., canola oil Health code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g., chloroform Reactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g., liquid nitrogen Special hazards (white): no codeNFPA 704 four-colored diamond
1
2
0
Flash point 127 °C (261 °F; 400 K) [1]
US health exposure limits (NIOSH):
PEL (Permissible)
 none[3]
REL (Recommended)
 TWA 10 mg/m3[3]
IDLH (Immediate danger)
 N.D.[3]
Related compounds
Related compounds
 Butylated hydroxyanisole
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
YesY verify (what is YesYN ?)
Infobox references

Butylated hydroxytoluene (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties.[4] European and U.S. regulations allow small amounts to be used as a food additive. In addition to this use, BHT is widely used to prevent oxidation in fluids (e.g. fuel, oil) and other materials where free radicals must be controlled.

Occurrence

Phytoplankton, including the green algae Botryococcus braunii, as well as three different cyanobacteria (Cylindrospermopsis raciborskii, Microcystis aeruginosa and Oscillatoria sp.) are capable of producing BHT. Confirmation was made via gas chromatography–mass spectrometry analysis.[5]

Production

Industrially, BHT is prepared by the reaction of p-cresol (4-methylphenol) with isobutylene (2-methylpropene) catalyzed by sulfuric acid: [6]

CH3(C6H4)OH + 2 CH2=C(CH3)2 → ((CH3)3C)2CH3C6H2OH

Alternatively, BHT is prepared from 2,6-di-tert-butylphenol by hydroxymethylation or aminomethylation followed by hydrogenolysis.

Reactions

The species behaves as a synthetic analog of vitamin E, primarily acting as a terminating agent that suppresses autoxidation, a process whereby unsaturated (usually) organic compounds are attacked by atmospheric oxygen. BHT stops this autocatalytic reaction by converting peroxy radicals to hydroperoxides. It effects this function by donating a hydrogen atom:

RO2. + ArOH → ROOH + ArO.
RO2. + ArO. → nonradical products

where R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants. Each BHT consumes two peroxy radicals.[7]

Applications

BHT is listed under three categories in catalogues and databases, such as food additive, household product ingredient, industrial additive, personal care product/cosmetic ingredient, pesticide ingredient, plastic/Rubber ingredient and Medical/Veterinary/Research[8]

Food additive

BHT is primarily used as an antioxidant food additive. In the United States, it is classified as generally recognized as safe (GRAS) based on a National Cancer Institute study from 1979 in rats and mice.[9] It is approved for use in the U.S. by the Food and Drug Administration: For example, 21 CFR § 137.350(a)(4) allows BHT up to 0.0033% by weight in "enriched rice", while 9 CFR § 381.147(f)(1) allows up to 0.01% in poultry "by fat content". It is permitted in the European Union under E321.[10] It is forbidden as food additive in Japan (since 1958), Romania, Sweden, and Australia. Since the 1970s, BHT has been steadily replaced with BHA. Some food companies have voluntarily eliminated BHT from their products. Others like General Mills and Kellogg's announced in February 2015, following a petition by Vani Hari, that they were going to phase it out.[11]

Antioxidant

BHT is also used as an antioxidant in products such as cosmetics, pharmaceuticals, rubber, electrical transformer oil (at 0.35%),[12] and embalming fluid. In the petroleum industry, where BHT is known as the fuel additive AO-29, it is used in hydraulic fluids, turbine and gear oils, and jet fuels.[13] BHT is also used to prevent peroxide formation in diethyl ether and other laboratory chemicals.[14]

Some additive products contain BHT as their primary ingredient, while others contain the chemical merely as a component of their formulation, sometimes alongside butylated hydroxyanisole (BHA).

Health effects

Debate surrounds the link of BHT to cancer risk, asthma and behavioral issues in children;[15] some studies show a potential to increase and some showing a decreased risk.[16][17][18] There is in vitro indication for endocrine disruption with effect on the testes and thyroid.[19] Because of this uncertainty the consumer group Center for Science in the Public Interest recommend to avoid BHT and puts BHT in its "caution" column.[20] The National Cancer Institute determined in 1979 that it was noncarcinogenic in a mouse model.[9]

BHT is marketed as a health food supplement in capsule form. It has been reported to have anti-viral effects, particularly in use against herpes family viruses, sometimes in combination with L-lysine and vitamin C.[21][22][23][24][25][26][27] This latter use has made it into some of the more popular literature.[28][29][30]

Closely related phenol antioxidants exhibit low toxicity. For example, the LD50 of 2,6-di-tert-butylphenol is greater than 9 g/kg.[6]

See also

References

  1. 1 2 3 BUTYLATED HYDROXYTOLUENE (ICSC)
  2. ↑ KEMI – Swedish Chemicals Agency – read the 1'st of Marts 2010 on
  3. 1 2 3 4 "NIOSH Pocket Guide to Chemical Hazards #0246". National Institute for Occupational Safety and Health (NIOSH).
  4. ↑ Yehye, Wageeh A.; Rahman, Noorsaadah Abdul; Ariffin, Azhar; Abd Hamid, Sharifah Bee; Alhadi, Abeer A.; Kadir, Farkaad A.; Yaeghoobi, Marzieh (2015). "Understanding the chemistry behind the antioxidant activities of butylated hydroxytoluene (BHT): A review". European Journal of Medicinal Chemistry 101: 295–312. doi:10.1016/j.ejmech.2015.06.026. PMID 26150290.
  5. ↑ Babu B, Wu JT (December 2008). "Production of Natural Butylated Hydroxytoluene as an Antioxidant by Freshwater Phytoplankton" (PDF). Journal of Phycology 44 (6): 1447–1454. doi:10.1111/j.1529-8817.2008.00596.x.
  6. 1 2 Helmut Fiege, Heinz-Werner Voges, Toshikazu Hamamoto, Sumio Umemura, Tadao Iwata, Hisaya Miki, Yasuhiro Fujita, Hans-Josef Buysch, Dorothea Garbe, Wilfried Paulus "Phenol Derivatives" in Ullmann's Encyclopedia of Industrial Chemistry, Wiley-VCH, Weinheim, 2002. doi:10.1002/14356007.a19_313 Article Online Posting Date: June 15, 2000.
  7. ↑ Burton, G. W.; Ingold, K. U., "Autoxidation of biological molecules. 1. Antioxidant activity of vitamin E and related chain-breaking phenolic antioxidants in vitro", Journal of the American Chemical Society, 1981, volume 103, pp 6472 – 6477. doi:10.1021/ja00411a035
  8. ↑ US Dept of Health & Human Services. Household Products Database. .US EPA. InertFinder. . US National Library of Medicine. Haz-Map. . US National Library of Medicine. Hazardous Substances Data Bank. .
  9. 1 2 Bioassay of Butylated Hydroxytoluene (BHT) for Possible Carcinogenicity, National Cancer Institute, CARCINOGENESIS Technical Report Series No. 150, 1979, 128 pp National Institutes of Health
  10. ↑ "Scientific Opinion on the re-evaluation of butylated hydroxytoluene BHT (E 321) as a food additive | European Food Safety Authority". www.efsa.europa.eu. Retrieved 2015-10-04.
  11. ↑ James Hamblin (11 February 2015). "The Food Babe: Enemy of Chemicals". The Atlantic. Retrieved 12 September 2015.
  12. ↑ Ficha de Datos de Seguridad, Transformador 64, benco.com, page 1, retrieved December 29, 2008, (español).
  13. ↑ Michael Ash, Irene Ash, Handbook of Preservatives, Synapse Information Resources, 2004. ISBN 1-890595-66-7.
  14. ↑ "Diethyl ether, contains 1 ppm BHT as inhibitor, anhydrous, ≥99.7%". Sigma Aldrich. Retrieved 11 September 2012.
  15. ↑ "Butylated hydroxytoluene (BHT)", IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, 1986;40:161-206.
  16. ↑ Kensler TW, Egner PA, Trush MA, Bueding E, Groopman JD, "Modification of aflatoxin B1 binding to DNA in vivo in rats fed phenolic antioxidants, ethoxyquin and a dithiothione", Carcinogenesis, 1985;6(5):759-63.
  17. ↑ Williams GM, Iatropoulos MJ, "Inhibition of the hepatocarcinogenicity of aflatoxin B1 in rats by low levels of the phenolic antioxidants butylated hydroxyanisole and butylated hydroxytoluene", Cancer Lett. 1996;104(1):49-53.
  18. ↑ Franklin RA, "Butylated hydroxytoluene in sarcoma-prone dogs", Lancet. 1976;1(7972):1296.
  19. ↑ Hughes PJ, McLellan H, Lowes DA, Khan SZ, Bilmen JG, Tovey SC, Godfrey RE, Michell RH, Kirk CJ, Michelangeli F. Estrogenic alkylphenols induce cell death by inhibiting testis endoplasmic reticulum Ca2+ pumps. Biochem Biophys Res Commun 277(3):568-574.2000.
  20. ↑ "Two Preservatives to Avoid?". Berkeley Wellness. University of California Berkeley. February 1, 2011. Retrieved 12 September 2015.
  21. ↑ Snipes W, Person S, Keith A, Cupp J, "Butylated hydroxytoluene inactivates lipid-containing viruses", Science. 1975;188(4183):64-6.
  22. ↑ Brugh M Jr, "Butylated hydroxytoluene protects chickens exposed to Newcastle disease virus. Science", 1977;197(4310):1291-2.
  23. ↑ Richards JT, Katz ME, Kern ER, "Topical butylated hydroxytoluene treatment of genital herpes simplex virus infections of guinea pigs", Antiviral Res. 1985;5(5):281-90.
  24. ↑ Kim KS, Moon HM, Sapienza V, Carp RI, Pullarkat R, "Inactivation of cytomegalovirus and Semliki Forest virus by butylated hydroxytoluene", J Infect Dis. 1978;138(1):91-4.
  25. ↑ Pirtle EC, Sacks JM, Nachman RJ, "Antiviral effectiveness of butylated hydroxytoluene against pseudorabies (Aujeszky’s disease) virus in cell culture, mice, and swine", Am J Vet Res. 1986;47(9):1892-5.
  26. ↑ Chetverikova LK, Ki’ldivatov II, Inozemtseva LI, Kramskaia TA, Filippov VK, et al. "Factors of antiviral resistance in the pathogenesis of influenza in mice", Vestn Akad Med Nauk SSSR. 1989;(11):63-8. [in Russian]
  27. ↑ Chetverikova LK, Inozemtseva LI, "Role of lipid peroxidation in the pathogenesis of influenza and search for antiviral protective agents" Vestn Ross Akad Med Nauk. 1996;(3):37-40. [in Russian]
  28. ↑ Pearson D, Shaw S, "Life Extension: A Practical Scientific Approach", New York, NY: Warner Books, Inc.; 1982:206-207.
  29. ↑ Mann JA, Fowkes SW, "Wipe Out Herpes with BHT", Manhattan Beach, Calif: MegaHealth Society; 1983.
  30. ↑ Fowkes SW, "The BHT Book", 2010, a free PDF e-publication, downloadable from Project Wellbeing (/steve page).

External links

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