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. 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 (BHT), also known as dibutylhydroxytoluene, is a lipophilic organic compound, chemically a derivative of phenol, that is useful for its antioxidant properties. 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. 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. Industrially, BHT is prepared by the reaction of p-cresol (4-methylphenol) with isobutylene (2-methylpropene) catalyzed by sulfuric acid: Alternatively, BHT is prepared from 2,6-di-tert-butylphenol by hydroxymethylation or aminomethylation followed by hydrogenolysis. 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: where R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants. Each BHT consumes two peroxy radicals. 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. 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. 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. 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.