BHT, butyl-hydroxytoluene

To obtain maximum lifetime, the oxidants must not be lost during service. A major potential source of loss is the evaporation of the antioxidant. Evaporation is often observed with BHT (butylated hydroxytoluene), a monomeric phenol, and to avoid evaporation less volatile, higher molecular weight antioxidants are used (i.e. bisphenols). 

BHT (butylated hydroxytoluene) is sometimes added as an antioxidant preservative to keep the oils from going rancid. 

AA = amonium acetate. ACN = acetonitrile. BHT = butylated hydroxytoluene. CHjClj = dichloromethane. HEX = hexane. IS = internal standard. MeOH = methanol. RT = room temperature. TEA = triethylamine. TBME = tert-butyl methyl ether. THE = tetrahydrofuran. 

Oxidative addition of a silyl-protected 4-(bromomethyl)phenol precursor to (tme-da)Pd(II)Me2 (tmeda = tetramethylethylenediamine), followed by ethane reductive elimination, resulted in formation of the benzylic complex 16 (Scheme 3.10). Exchange of tmeda for a diphosphine ligand (which is better suited for stabilizing the ultimate Pd(0) QM complex), followed by removal of the protecting silyl group with fluoride anion, resulted in the expected p-QM Pd(0) complex, 17, via intermediacy of the zwitterionic Pd(II) benzyl complex. In this way a stable complex of p-BHT-QM, 17b, the very important metabolite of the widely used food antioxidant BHT20 (BHT = butylated hydroxytoluene) was prepared. Similarly, a Pd(0) complex of the elusive, simplest /)-QM, 17a, was obtained (Scheme 3.10). 

Note THF = tetrahydrofuran BHT = butylated hydroxytoluene, an antioxidant Camptothecin (CM) = causes inhibition of the DNA enzyme topoisomerase (Top 1) which induces DNA damage and apoptosis DHT = dihydrotestosterone PrEC = normal prostate stromal cells LNCaP, PC-3, DU-145 = neoplastic prostate epithelial cells (See Table 21.1). 

Synonyms BHT butylated hydroxytoluene DBPC 2,6-bis(l,l-dimethylethyl)-4-methyl-phenol... 

Antioxidants Ascorbic acid, BHA (butylated hydroxyanisole), BHT (butylated hydroxytoluene tocopherols)... 

Abbreviations. BHA, butylated hydi oxyanisole BHT, butylated hydroxytoluene EDTA, edetate calcium disodium. 

BHT, butylated hydroxytoluene BHA, butylated hydroxyanisole EDTA, ethylenediaminetetraacetic acid MeOH, methanol EtOH, ethanol 2-PrOH, 2-propanol BuOH, butanol MeCN, acetonitrile CHC13, chloroform CH2C12, dichloromethane (methylene chloride) THF, tetrahydrofuran DMF, dimethylformamide DMSO, dimethylsulfoxide MTBE, methyl tert-butyl ether. 

Notes LOD, limit of detection MeOH, methanol EtOH, ethanol ACN, acetonitrile MTBE, methyl tert-butyl ether DCM, dichloromethane THF, tetrahy-drofuran KOH, potassium hydroxide SFE, supercritical fluid extraction MS, mass spectrometry HPLC, high-performance liquid chromatography DAD, diode array detector PDA, photodiode array detector FD, fluorescence detector ECD, electrochemical detector ESI, electrospray ionization APCI, atmosphere pressure chemical ionization TLC, thin layer chromatography FAB, fast atom bombardment NMR, nuclear magnetic resonance BHT, butylated hydroxytoluene SPE, solid phase extraction. 

Compounds that are in direct contact with air when in the final product, for example as in powder products or in soap, are particularly at risk from oxidation, and the head space above the product is likely therefore to become rich in the breakdown products of oxidation. For this reason the packaging usually allows for a certain amount of "breathing" so as to let these "off-odors" escape rather than their being reabsorbed into the product. A number of products exist, generally classed as antioxidants, for example, BHT (butyl hydroxytoluene), that help to inhibit these oxidation reactions. These antioxidants are often added to citrus oils, or to compounds to prolong their shelf life, or to the final product. 

Ratio = blend ratio soybean oil fatty acid methyl esters (SME) in low-sulfur (<500ppm) No. 2 petrodiesel (LSD) where BO is 0% SME and B20 contains 20 vol% SME BHA = butylated hydroxyanisole BHT = butylated hydroxytoluene TBHQ = tert-butylhydroquinone. 

Figure 1.1. Selected Synthetic Antioxidants. BHT = Butylated hydroxytoluene TBHQ = ferf-butylhydroxyquinone BHA = butylated hydroxyanisole TBHT = ferf-butyl hydroxytoluene Trolox = 6-hydroxy-2,5,7,8-tetramethylchroman-2-carboxylic acid.

BHT butylated hydroxytoluene (2,6-di-t-butyl-p- DMAD dimethyl acetylenedicarboxylate... 

AP = ascorbyl palmitate, BHA = butylated hydroxyanisole, BHT = butylated hydroxytoluene, TDPA = thiodipropionic acid, PG = propyl gallate, NDGA = nor-dihydroguaiaretic acid, TBHQ 2- er -butylhydroquinone. 

In addition to its use in resins and adhesives, phenol is also the starting material for the synthesis of chlorinated phenols and the food presen-atives BHT (butylated hydroxytoluene) and BHA (butylated hydroxy-anisole). Pentachlorophenol, a widely used wood preservative, is prepared by reaction of phenol with excess CI2. The herbicide 2,4-D (2,4-dich)< -phenoxyacetic acid) is prepared from 2,4-dichlorophenol, and the hospital antiseptic agent hexachlorophene is prepared from 2,4,5-trichlorophenol. 

Reference compounds. NT not tested, BHT butylated hydroxytoluene Al 12-methoxy-7-acetoxyroyleanone (or 7-acetoxybarrilierone)... 

BCF Basophil chemotactic factor B-CFC Basophil colony-forming cell BCG Bacillus Calmette-Guerin BCNU l,3-bis(2-chloroethyl)-l-nitrosourea bFGF Basic fibroblast growth factor Bg Birbeck granules BHR Bronchial hyperresponsiveness BHT Butylated hydroxytoluene b.i.d. Bis in die (twice a day)... 

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. 

Impurities are described in many texts on solvents [4, 5]. Many organic impurities can be identified by GC or GC/MS techniques for instance, MIBK can be found to contain mesityl oxide, the precursor to the manufacture of MIBK (Figure 4.6) [20]. Common impurities in solvents include H20, DMF [21], and AcOFl (in EtOAc and other solvents). Some solvents are inhibited with trace amounts of antioxidants, e.g., CH2C12 (stabilized with amylene or cyclohexane) andTFIF and 2-Me-THF (stabilized with BHT, butylated hydroxytoluene ). These impurities can influence the desired chemistry positively [22] and negatively, so and they should be considered. 

FIGURE 1. Oxygen uptake profiles for oxidation of 0.12 M methyl hnoleate in 0.5 M SDS micelles, initiated by 0.03 M of the thermal azo initiator di-tcrt-butylhyponitrite, comparing the effects of the retarder melatonin (R) with phenolic antioxidants U—uninhibited oxidation, R1— 8.72 X 10-5 melatonin, R2—87.2 x 10-5 melatonin, a-Toc—8.72 x 10-5 a-Toc, nib—8.72 x 10 5 M BHT [butylated hydroxytoluene (2,6-di-t-butyl-4-methylphenol)], Vc—8.72 x 10 5 M Trolox (2,5,6,7-tetramethyl-2-carboxy-5-hydroxychroman), Va—8.72 x 10-5 PMHC (2,2,5,6,7-pen-tamethyl-5-hydroxychroman). Reproduced by permission of Elsevier Science from Reference 283... 

Abbreviations BHA, butylated hydroxyanisole BHT, butylated hydroxytoluene DTT, dithiothreitol EDTA, ethylehediamihetetraacetic acid. 

QUESTION 10.9 BHT (butylated hydroxytoluene) is an antioxidant that is widely used as a food... 

Abbreviations BA benzyl alcohol BHT butylated hydroxytoluene BKC benzalkonium chloride BzCI benethonium chloride CCS croscarmellose sodium cit citric acid dex dextrose IPM isopropyl myristate KP potassium phosphates MCC microcrystalline cellulose MeC methyl cellulose MePB methyl parabens Mr relative molecular mass NaCit Na citrate NaCMC Na carboxymethylcellulose Na2edta disodium edetate NaP sodium phosphate PEG polyethylene glycol PE-OH phenylethyl alcohol PG propylene glycol pov povidone PrPB propyl parabens SAI steroidal anti-inflammatory Tw Tween (polysorbate)... 

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