Butylated hydroxytoluene antioxidant/food preservative

Probtom 19.31 From readily available phenolic compounds, synthesize the antioxidant food preservatives (a) BHA (ferr-butylatedhydroxyanisole, a mixture of 2- and 3-ferf-butyl-4-methoxyphenol (b) bht (rert-butylated hydroxytoluene). ... 

Goodman DL, McDonnell JT, Nelson HS, Vaughan TR, Weber RW. Chronic urticaria exacerbated by the antioxidant food preservatives, butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). J Allergy Clin Immunol 1990 86(4 Pt 1) 570-5. 

Annex III lays down the conditions of use for permitted preservatives and antioxidants, with lists of foods and maximum levels in each case. Part A lists the sorbates, benzoates and p-hydroxybenzoates, E 200-E 219 part B lists sulphur dioxide and the sulphites, E 220-E 228 part C lists other preservatives with their uses, including nisin, dimethyl dicarbonate and substances allowed for surface treatment of certain fruits, E 249 potassium nitrite, E 250 sodium nitrite, E 251 sodium nitrate and E 252 potassium nitrate, E 280-E 283 propionic acid and the propionates part D lists the antioxidants E 320 butylated hydroxyanisole (BHA), E 321 butylated hydroxytoluene (BHT), E 310 propyl gallate, E 311 octyl gallate, E 312 dodecyl gallate, E 315 eiythorbic acid and E 316 sodium erythorbate. 

Free radicals can also be stabilized kinetically by steric shielding of the radical centers. Such free radicals are called persistent. Examples of persistent free radicals include perchlorotrityl, galvinoxyl, and the radical derived from BHT (butylated hydroxytoluene, 2,6-di-tert-butyl-4-methylphenol), an antioxidant that is used as a food preservative. 

Butylated hydroxyanisole (BYOO-til-ay-ted hi-DROK-see-ANN-i-sole) and butylated hydroxytoluene (BYOO-til-ay-ted hi-DROK-see-TOL-yoo-een) are very popular food additives used to preserve fats and oils. They both are antioxidants, which are compounds that prevent oxygen from reacting with substances and changing them into other materials. BHA and BHT prevent the oxidation of fats and oils that would convert them into rancid, foul-smelling, harmful products. 

The widely used antioxidant and food preservative called BHA (butylated hydroxyanisole) is actually a mixture of 2-rert-butyl-4-methoxyphenol and 3-tert-hutyl-4-methoxyphenol. BHA is synthesized from A>-methoxyphenol and 2-methylpropene. (a) Suggest how this is done, (b) Another widely used antioxidant is BHT (butylated hydroxytoluene). BHT is actually 2,6-di-rerr-butyl-4-methylphenol, and the raw materials used in its production are /)-cresol and 2-methylpropene. What reaction is used here ... 

CI.37 A compound called butylated hydroxytoluene, or BHT, with a molecular formula C15H24O, is added to preserve foods such as cereal. As an antioxidant, BHT reacts with oxygen in the cereal container, which protects the food from spoilage. (2.6, 2.7, 8.4, 17.3, 17.4)... 

Synthetic phenol derivatives are widely used as antioxidants and preservatives in the food industry. Perhaps two of the most familiar are 2-(l,l-dimethylethyI)-4-methoxyphenoI (butylated hydroxyanisole, or BHA) and 2,6-bis(l,l-dimethyIethyI)-4-methyIphenoI (butylated hydroxytoluene, or BHT see Exercise 16-14). For example, addition of BHA to butter increases its storage life from months to years. Both BHA and BHT function like vitamin E, reducing oxygen radicals and interrupting the propagation of oxidation processes. 

---