Butylated hydroxytoluene

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Butylated hydroxytoluene
Skeletal formula of butylated hydroxytoluene
Ball-and-stick model of the butylated hydroxytoluene molecule
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
Identifiers
  • 128-37-0 YesY
3D model (JSmol)
  • Interactive image
ChEBI
  • CHEBI:34247 YesY
ChEMBL
  • ChEMBL146 YesY
ChemSpider
  • 13835296 YesY
ECHA InfoCard 100.004.439
EC Number 204-881-4
E number E321 (antioxidants, ...)
KEGG
  • D02413 YesY
PubChem CID
  • 31404
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
GHS pictograms The environment pictogram in the Globally Harmonized System of Classification and Labelling of Chemicals (GHS)
GHS signal word Warning
H400, H410
P273, P391, P501
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]
Lethal dose or concentration (LD, LC):
LD50 (median dose)
> 2,000 mg/kg (dermal, rat)[4]
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.[5] 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.[6]

Production

Industrially, BHT is prepared by the reaction of p-cresol (4-methylphenol) with isobutylene (2-methylpropene) catalyzed by sulfuric acid: [7]

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.[8]

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.[9]

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.[10] 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.[11]

Since the 1970s, BHT has been steadily replaced with butylated hydroxyanisole (BHA).[citation needed] Some food companies have voluntarily eliminated BHT from their products or have announced that they were going to phase it out.[12]

Antioxidant

BHT is also used as an antioxidant in products such as cosmetics, pharmaceuticals, rubber, electrical transformer oil (at 0.35%),[13] 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.[14] BHT is also used to prevent peroxide formation in diethyl ether and other laboratory chemicals.[15]

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).[citation needed]

Derivatives

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.[16][17] There is, however, some debate surrounding a possible link between BHT and cancer risk, asthma, and behavioral issues in children;[18] some studies show a potential to increase risk and some to decrease risk.[19][20][21] 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.[22] The National Cancer Institute determined in 1979 that it was noncarcinogenic in a mouse model.[10] BHT has low acute toxicity,[4] as do other closely related phenol antioxidants. For example, the LD50 of 2,6-di-tert-butylphenol is greater than 9 g/kg.[7]

In early stage research, BHT has shown anti-viral activity.[23][24][25][26][27][28][29]

References

  1. ^ a b c 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. ^ a b c d "NIOSH Pocket Guide to Chemical Hazards #0246". National Institute for Occupational Safety and Health (NIOSH). 
  4. ^ a b Record in the GESTIS Substance Database of the Institute for Occupational Safety and Health
  5. ^ 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. 
  6. ^ 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. 
  7. ^ 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.
  8. ^ 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
  9. ^ US Dept of Health & Human Services. Household Products Database. [1].US EPA. InertFinder. [2]. US National Library of Medicine. Haz-Map. [3]. US National Library of Medicine. Hazardous Substances Data Bank. [4].
  10. ^ a b Bioassay of Butylated Hydroxytoluene (BHT) for Possible Carcinogenicity, National Cancer Institute, CARCINOGENESIS Technical Report Series No. 150, 1979, 128 pp National Institutes of Health
  11. ^ "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. 
  12. ^ James Hamblin (11 February 2015). "The Food Babe: Enemy of Chemicals". The Atlantic. Retrieved 12 September 2015. 
  13. ^ Ficha de Datos de Seguridad, Transformador 64 Archived 2011-09-05 at the Wayback Machine., benco.com, page 1, retrieved December 29, 2008, (español).
  14. ^ Michael Ash, Irene Ash, Handbook of Preservatives, Synapse Information Resources, 2004. ISBN 1-890595-66-7.
  15. ^ "Diethyl ether, contains 1 ppm BHT as inhibitor, anhydrous, ≥99.7%". Sigma Aldrich. Retrieved 11 September 2012. 
  16. ^ "GRAS Substances (SCOGS) Database". Food and Drug Administration. 
  17. ^ "Code of Federal Regulations Title 21". 
  18. ^ 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. 
  19. ^ 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. 
  20. ^ 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. 
  21. ^ Franklin, R. A (1976). "Butylated hydroxytoluene in sarcoma-prone dogs". Lancet. 1 (7972): 1296. doi:10.1016/s0140-6736(76)91766-9. PMID 73719. 
  22. ^ "Two Preservatives to Avoid?". Berkeley Wellness. University of California Berkeley. February 1, 2011. Retrieved 12 September 2015. 
  23. ^ Snipes, W; Person, S; Keith, A; Cupp, J (1975). "Butylated hydroxytoluene inactivated lipid-containing viruses". Science. 188 (4183): 64–6. doi:10.1126/science.163494. PMID 163494. 
  24. ^ 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. 
  25. ^ 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. 
  26. ^ 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. 
  27. ^ 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. 
  28. ^ 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. 
  29. ^ 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. 

External links

  • Why are BHA and BHT in foods? Are they safe?
  • CDC – NIOSH Pocket Guide to Chemical Hazards
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