Butylated hydroxytoluene

Chembox new
Name = Butylated hydroxytoluene
ImageFile = 2,6-bis(1,1-dimethylethyl)-4-methylphenol.svg
ImageSize = 200px
ImageName = Butylated hydroxytoluene
IUPACName = 2,6-bis(1,1-dimethylethyl)-4-methylphenol
OtherNames = 2,6-di-"tert"-butyl-4-methylphenol; 2,6-di-"tert"-butyl-"p"-cresol (DBPC); butylated hydroxytoluene; BHT
Section1 = Chembox Identifiers
CASNo = 128-37-0
EINECS = 204-881-4
RTECS = GO7875000
Section2 = Chembox Properties
Formula = C₁₅H₂₄O
MolarMass = 220.35 g/mol
Appearance = white powder
Density = 1.048 g/cm³, solid
Solubility = insol.
MeltingPt = 70-73 °C
BoilingPt = 265 °C (538.15 K)
pKa =
Section7 = Chembox Hazards
ExternalMSDS = [http://ptcl.chem.ox.ac.uk/MSDS/DI/2,6-di-t-butyl-p-cresol.html External MSDS]
MainHazards = Flammable
FlashPt = 127 °C
RPhrases = 22-36 37 38
SPhrases = 26-36
Section8 = Chembox Related
OtherCpds = butylated hydroxyanisole

Butylated hydroxytoluene (BHT), also known as Butylhydroxytoluene, is a lipophilic (fat-soluble) organic compound that is primarily used as an antioxidant food additive (E number E321) as well as in cosmetics, pharmaceuticals, jet fuels, rubber, petroleum products, and embalming fluid.

Chemistry

BHT is produced by alkylation reaction of "p"-cresol with isobutylene. The species behaves as a synthetic analogue 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 productswhere R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants. One can see that each BHT consumes two peroxy radicals. [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]

In the chemical industry it is added to tetrahydrofuran and diethyl ether in order to inhibit the formation of dangerous organic peroxides.

Controversy

The compound has been banned for use in food in Japan (1958), Romania, and Australia. The US has barred it from infant foods. Some food industries have voluntarily eliminated it from their products. However, BHT is also marketed as a health food supplement in capsule form. In different studies, BHT has beenreported to cure some cancers, but to encourage others. BHT is well studied because ofpublic concern over synthetic preservatives. Since the 1970s, BHT has been steadily replaced with the less studied BHA; however, BHT is still used in some foods.

References

ee also

*Butylated hydroxyanisole (BHA)

External links

* [http://bht-coldsores.blogspot.com An experiment on the effectiveness BHT has against herpes & cold sore outbreaks]
* [http://chemistry.about.com/library/weekly/aa082101a.htm Why are BHA and BHT in foods? Are they safe?]
* [http://ntp.niehs.nih.gov/index.cfm?objectid=070510F7-946E-0334-8C3427E3D9734FD0 Bioassay of BHT, includes structure]
* [http://www.inchem.org/documents/icsc/icsc/eics0841.htm BUTYLATED HYDROXYTOLUENE (ICSC)]
* [http://www.shadetreephysics.com/bht.htm Butylated Hydroxytoluene (BHT) Antioxidant]