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.[6] 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.

Butylated hydroxytoluene
Names
Preferred IUPAC name
2,6-Di-tert-butyl-4-methylphenol
Other names
2,6-Di-tert-butyl-p-cresol
3,5-Di-tert-butyl-4-hydroxytoluene
DBPC
BHT
E321
AO-29
Avox BHT
Additin RC 7110
Dibutylated hydroxytoluene
4-Methyl-2,6-di-tert-butyl phenol
3,5-(Dimethylethyl)-4-hydroxytoluene
Identifiers
CAS Number
3D model (JSmol)
ChEBI
ChEMBL
ChemSpider
ECHA InfoCard 100.004.439
EC Number
  • 204-881-4
E number E321 (antioxidants, ...)
KEGG
PubChem CID
RTECS number
  • GO7875000
UNII
Properties
Chemical formula
 C15H24O
Molar mass 220.356 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]
Solubility in water
 1.1 mg/L (20 °C)[2]
log P 5.32[3]
Vapor pressure 0.01 mmHg (20°C)[4]
Hazards
Main hazards Flammable
Safety data sheet External MSDS
GHS pictograms
GHS Signal word Warning
GHS hazard statements
 H400, H410
GHS precautionary statements
 P273, P391, P501
NFPA 704 (fire diamond)
Flammability code 1: Must be pre-heated before ignition can occur. Flash point over 93 °C (200 °F). E.g. canola oilHealth code 2: Intense or continued but not chronic exposure could cause temporary incapacitation or possible residual injury. E.g. chloroformReactivity code 0: Normally stable, even under fire exposure conditions, and is not reactive with water. E.g. liquid nitrogenSpecial hazards (white): no code
1
2
0
Flash point 127 °C (261 °F; 400 K) [1]
Lethal dose or concentration (LD, LC):
> 2,000 mg/kg (dermal, rat)[5]
NIOSH (US health exposure limits):
PEL (Permissible)
 none[4]
REL (Recommended)
 TWA 10 mg/m3[4]
IDLH (Immediate danger)
 N.D.[4]
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).
Y verify (what is YN ?)
Infobox references

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. The fruit lychee also produces BHT in its pericarp. Confirmation was made via gas chromatography–mass spectrometry analysis.[7][8]

Production

Industrially, BHT is prepared by the reaction of p-cresol (4-methylphenol) with isobutylene (2-methylpropene) catalyzed by sulfuric acid: [9]

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.[10]

Applications

BHT is listed under several 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.[11]

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.[12] 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.[13]

BHT is used as a preservative ingredient in some foods. With this usage BHT maintains freshness or prevents spoilage; it may be used to decrease the rate at which the texture, color, or flavor of food changes.[14]

Since the 1970s, BHT has been steadily replaced with butylated hydroxyanisole (BHA). Some food companies have voluntarily eliminated BHT from their products or have announced that they were going to phase it out.[15]

Antioxidant

BHT is also used as an antioxidant in products such as metalworking fluids, cosmetics, pharmaceuticals, rubber, electrical transformer oil (at 0.35%),[16] 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.[17] BHT is also used to prevent peroxide formation in diethyl ether and other laboratory chemicals.[18] It is added to certain monomers as a polymerisation inhibitor to facilitate their safe storage. 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

The US Food and Drug Administration classifies BHT as generally recognized as safe (GRAS) as a food preservative when used according to approved uses.[19][20] There is, however, some debate surrounding a possible link between BHT and cancer risk, asthma, and behavioral issues in children;[21] some studies show a potential to increase risk and some to decrease risk.[22][23][24] 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.[25] The National Cancer Institute determined in 1979 that it was noncarcinogenic in a mouse model.[12] BHT has low acute toxicity,[5] as do other closely related phenol antioxidants. For example, the LD50 of 2,6-di-tert-butylphenol is greater than 9 g/kg.[9]

In early stage research, BHT has shown anti-viral activity.[26][27][28][29][30][31][32]

References
  1. BUTYLATED HYDROXYTOLUENE (ICSC)
  2. KEMI – Swedish Chemicals Agency – read the 1'st of Marts 2010 on Archived 2011-08-11 at the Wayback Machine
  3. "Butylated hydroxytoluene_msds".
  4. NIOSH Pocket Guide to Chemical Hazards. "#0246". National Institute for Occupational Safety and Health (NIOSH).
  5. Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  6. 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.
  7. 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. PMID 27039859.
  8. Jiang G, Lin S, Wen L, Jiang Y, Zhao M, Chen F, Prasad KN, Duan X, Yang B (15 January 2013). "Identification of a novel phenolic compound in litchi (Litchi chinensis Sonn.) pericarp and bioactivity evaluation". Food Chemistry. 136 (2): 563–8. doi:10.1016/j.foodchem.2012.08.089. PMID 23122098.
  9. 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.
  10. 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
  11. 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. .
  12. Bioassay of Butylated Hydroxytoluene (BHT) for Possible Carcinogenicity, National Cancer Institute, CARCINOGENESIS Technical Report Series No. 150, 1979, 128 pp National Institutes of Health
  13. "Scientific Opinion on the re-evaluation of butylated hydroxytoluene BHT (E 321) as a food additive | European Food Safety Authority". www.efsa.europa.eu. 2012-03-07. Retrieved 2015-10-04.
  14. "Food Additives & Ingredients > Overview of Food Ingredients, Additives & Colors". www.fda.gov. Types of Ingredients: Preservatives[.] What They Do: Prevent food spoilage from [...]; maintain freshness[.] Examples of Uses: Fruit sauces and jellies, beverages, baked goods, cured meats, oils and margarines, cereals, dressings, snack foods, fruits and vegetables[.] Names Found on Product Labels: Ascorbic acid, citric acid, sodium benzoate, calcium propionate, sodium erythorbate, sodium nitrite, calcium sorbate, potassium sorbate, BHA, BHT, EDTA, tocopherols (Vitamin E)[.]
  15. James Hamblin (11 February 2015). "The Food Babe: Enemy of Chemicals". The Atlantic. Retrieved 12 September 2015.
  16. Ficha de Datos de Seguridad, Transformador 64 Archived 2011-09-05 at the Wayback Machine, benco.com, page 1, retrieved December 29, 2008, (español).
  17. Michael Ash, Irene Ash, Handbook of Preservatives, Synapse Information Resources, 2004. ISBN 1-890595-66-7.
  18. "Diethyl ether, contains 1 ppm BHT as inhibitor, anhydrous, ≥99.7%". Sigma Aldrich. Retrieved 11 September 2012.
  19. "GRAS Substances (SCOGS) Database". Food and Drug Administration.
  20. "Code of Federal Regulations Title 21".
  21. Butylated hydroxytoluene (BHT) (PDF) (Report). 40. World Health Organization: International Agency For Research On Cancer. 1986. pp. 161–206. Archived (PDF) from the original on 2015-09-05.
  22. Kensler, T. W; Egner, P. A; Trush, M. A; Bueding, E; Groopman, J. D (1985). "Modification of aflatoxin B1 binding to DNA in vivo in rats fed phenolic antioxidants, ethoxyquin and a dithiothione". Carcinogenesis. 6 (5): 759–63. doi:10.1093/carcin/6.5.759. PMID 3924431.
  23. Williams, G. M; Iatropoulos, M. J (1996). "Inhibition of the hepatocarcinogenicity of aflatoxin B1 in rats by low levels of the phenolic antioxidants butylated hydroxyanisole and butylated hydroxytoluene". Cancer Letters. 104 (1): 49–53. doi:10.1016/0304-3835(96)04228-0. PMID 8640745.
  24. Franklin, R. A (1976). "Butylated hydroxytoluene in sarcoma-prone dogs". Lancet. 1 (7972): 1296. doi:10.1016/s0140-6736(76)91766-9. PMID 73719.
  25. "Two Preservatives to Avoid?". Berkeley Wellness. University of California Berkeley. February 1, 2011. Retrieved 12 September 2015.
  26. Snipes, W; Person, S; Keith, A; Cupp, J (1975). "Butylated hydroxytoluene inactivated lipid-containing viruses". Science. 188 (4183): 64–6. Bibcode:1975Sci...188...64S. doi:10.1126/science.163494. PMID 163494.
  27. Brugh, M (1977). "Butylated hydroxytoluene protects chickens exposed to Newcastle disease virus". Science. 197 (4310): 1291–2. Bibcode:1977Sci...197.1291B. doi:10.1126/science.897670. PMID 897670.
  28. Richards, J. T; Katz, M. E; Kern, E. R (1985). "Topical butylated hydroxytoluene treatment of genital herpes simplex virus infections of guinea pigs". Antiviral Research. 5 (5): 281–90. doi:10.1016/0166-3542(85)90042-7. PMID 2998276.
  29. Kim, K. S; Moon, H. M; Sapienza, V; Carp, R. I; Pullarkat, R (1978). "Inactivation of cytomegalovirus and Semliki Forest virus by butylated hydroxytoluene". The Journal of Infectious Diseases. 138 (1): 91–4. doi:10.1093/infdis/138.1.91. PMID 210237.
  30. Pirtle, E. C; Sacks, J. M; Nachman, R. J (1986). "Antiviral effectiveness of butylated hydroxytoluene against pseudorabies (Aujeszky's disease) virus in cell culture, mice, and swine". American Journal of Veterinary Research. 47 (9): 1892–5. PMID 3021025.
  31. Chetverikova, L. K; Ki'Ldivatov, I. Iu; Inozemtseva, L. I; Kramskaia, T. A; Filippov, V. K; Frolov, B. A (1989). "Factors of antiviral resistance in the pathogenesis of influenza in mice". Vestnik Akademii Meditsinskikh Nauk SSSR (in Russian) (11): 63–8. PMID 2623936.
  32. Chetverikova LK, Inozemtseva LI (1996). "Role of lipid peroxidation in the pathogenesis of influenza and search for antiviral protective agents". Vestn Ross Akad Med Nauk (in Russian). 3: 37–40.
This article is issued from Wikipedia. The text is licensed under Creative Commons - Attribution - Sharealike. Additional terms may apply for the media files.