Butylated hydroxytoluene

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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 images 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
Flash point 127 °C (261 °F; 400 K) [1]
US health exposure limits (NIOSH):
none[3]
TWA 10 mg/m3[3]
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 isYesY/N?)
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[edit]

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[edit]

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.

Applications[edit]

Food additive[edit]

BHT is primarily used as a food additive that exploits its antioxidant properties. In the United States, it is classified as generally recognized as safe (GRAS).[7] It is approved for use in European Union under E321 and in the U.S. by the Food and Drug Administration via regulation: 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". Meanwhile, it is forbidden to apply as food additive in Japan (since 1958), Romania, Sweden, and Australia. Nonetheless, some food companies have voluntarily eliminated this additive from their products, and since the 1970s, it has been steadily replaced with BHA.

Antioxidant[edit]

BHT is also used as an antioxidant additive in such diverse products as cosmetics, pharmaceuticals, rubber, electrical transformer oil (at 0.35%),[8] and embalming fluid. In the petroleum industry, where BHT is known as the fuel additive AO-29, it also finds uses in hydraulic fluids, turbine and gear oils, and jet fuels,[9] among other applications. BHT is also used to prevent peroxide formation in diethyl ether and other laboratory chemicals.[10]

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).

Reactions[edit]

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.[11]

Research[edit]

Debate surrounds the link of BHT to cancer risk, asthma and behavioral issues in children;[12] some studies show a potential to increase and some showing a decreased risk.[13][14][15] The National Toxicology Program has determined that it is noncarcinogenic in a mouse model.[7]

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.[16][17][18][19][20][21][22] This latter use has made it into some of the more popular literature.[23][24][25]

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[edit]

References[edit]

  1. ^ a b c BUTYLATED HYDROXYTOLUENE (ICSC)
  2. ^ KEMI - Swedish Chemicals Agency - read the 1'st of Marts 2010 on
  3. ^ a b c d "NIOSH Pocket Guide to Chemical Hazards #0246". National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ doi:10.1016/j.ejmech.2015.06.026
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  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. ^ a b 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. ^ a b Bioassay of Butylated Hydroxytoluene (BHT) for Possible Carcinogenicity, National Toxicology Program, National Institutes of Health
  8. ^ Ficha de Datos de Seguridad, Transformador 64, page 1, retrieved December 29, 2008, (español).
  9. ^ Michael Ash, Irene Ash, Handbook of Preservatives, Synapse Information Resources, 2004. ISBN 1-890595-66-7.
  10. ^ "Diethyl ether, contains 1 ppm BHT as inhibitor, anhydrous, ≥99.7%". Sigma Aldrich. Retrieved 11 September 2012. 
  11. ^ 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
  12. ^ "Butylated hydroxytoluene (BHT)", IARC Monographs on the Evaluation of Carcinogenic Risks to Humans, 1986;40:161-206.
  13. ^ 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.
  14. ^ 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.
  15. ^ Franklin RA, "Butylated hydroxytoluene in sarcoma-prone dogs", Lancet. 1976;1(7972):1296.
  16. ^ Snipes W, Person S, Keith A, Cupp J, "Butylated hydroxytoluene inactivates lipid-containing viruses", Science. 1975;188(4183):64-6.
  17. ^ Brugh M Jr, "Butylated hydroxytoluene protects chickens exposed to Newcastle disease virus. Science", 1977;197(4310):1291-2.
  18. ^ 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.
  19. ^ 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.
  20. ^ 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.
  21. ^ 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]
  22. ^ 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]
  23. ^ Pearson D, Shaw S, "Life Extension: A Practical Scientific Approach", New York, NY: Warner Books, Inc.; 1982:206-207.
  24. ^ Mann JA, Fowkes SW, "Wipe Out Herpes with BHT", Manhattan Beach, Calif: MegaHealth Society; 1983.
  25. ^ Fowkes SW, "The BHT Book", 2010, a free PDF e-publication, downloadable from Project Wellbeing (/steve page).

External links[edit]