Butylated hydroxytoluene

Butylated hydroxytoluene (BHT) is the organic compound with the formula MeC₆H₂(CMe₃)₂OH (Me = methyl). This lipophilic (fat-soluble) phenol 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.

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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 products

where R is alkyl or aryl, and where ArOH is BHT or related phenolic antioxidants. One can see that each BHT consumes two peroxy radicals.^[1]

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

Use in foods

BHT was patented in 1947 and received approval of the Food and Drug Administration for use as a food additive and preservative in 1954. BHT reacts with free radicals, slowing the rate of autoxidation in food, preventing changes in the food's color, odor, and taste.^[2] BHT is found in cereal, chewing gum and food high in fats such as potato chips and shortening.^[3][4]

Controversy

Concerns have been raised about the use of BHT in food products.^{[citation needed]} The compound has been banned for use in food in Japan (1958), Romania, Sweden, and Australia. The US has barred it from infant foods.^{[citation needed]} 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 been reported to cure some cancers, but to encourage others. BHT is well studied because of public concern over synthetic preservatives. BHT was largely removed from food in the 1970s, to be replaced with the less well studied BHA.

References

1. ^ 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
2. ^ Fujisawa, S.; Kadomab, Y.; Yokoe, I. "Radical-scavenging activity of butylated hydroxytoluene (BHT) and its metabolites" Chemistry and Physics of Lipids 130 (2004) pp. 189–195. DOI 10.1016/j.chemphyslip.2004.03.005.
3. ^ All Natural Me (2007). BHT ~ Should It Be In Food?. All Natural Me . Retrieved on 27 November, 2007.
4. ^ Center for Science in the Public Interest (2007). Food Additives - CSPI's Food Safety. CSPI . Retrieved on 27 November, 2007.

See also

• Butylated hydroxyanisole (BHA)