2, 6-di-tert-Butyl-4-methylphenol

Di-tert-butyl-p-cresol (2,6-di-tert-butyl-4-methylphenol, butylatedhydroxytoluene, BHT) [128-37-0] M 230.4, m 71.5 , pK 12.23. Dissolved in n-hexane at room temperature, then cooled with rapid stirring, to -60°. The ppte was separated, redissolved in hexane, and the process was repeated until the mother liquor was no longer coloured. The final product was stored under N2 at 0° [Blanchard J Am Chem Soc 82 2014 7960]. Also crystd from EtOH, MeOH, benzene, n-hexane, methylcyclohexane or pet ether (b 60-80°), and dried under vacuum. 

Figure 10.9 Cliromatogi ams of foitified coconut oil obtained by using (a) normal-phase HPLC and (b) GPC/noimal-phase HPLC. Peak identification is as follows 1 (a,b), DL-a-toco-pheryl acetate, 2 (b), 2,6-di-tert-butyl-4-methylphenol 2 (a) and 3 (b), retinyl acetate 3 (a) and 4 (b), tocol 4 (a) and 5 (b), ergocalciferol. Reprinted from Analytical Chemistry, 60, J. M. Brown-Thomas et al., Determination of fat-soluble vitamins in oil matrices by multidimensional liigh-peiformance liquid cliromatography , pp. 1929-1933, copyright 1988, with permission from the American Chemical Society.

SCHEME 9.9 Reversible alkylation of deoxynucleotides by a metabolite of 2,6,-di-tert-butyl-4-methylphenol. 

Meier, B. W. Gomez, J. D. Kirichenko, O. V. Thompson, J. A. Mechanistic basis for inflammation and tumor promotion in lungs of 2,6-di-tert-butyl-4-methylphenol-treated mice electrophilic metabolites alkylate and inactivate antioxidant enzymes. Chem. Res. Toxicol. 2007, 20, 199-207. 

BHT (2,6-di-tert-butyl-4-methylphenol), a phenolic antioxidant, on reaction with NO under neutral conditions, results in scavenging of the potentially harmful NO via radical reactions [143]. Sodium phenolate under basic conditions undergoes a Traube-type reaction at the ortho-position to produce a cupferron derivative [144]. When the ortho-positions are sterically blocked and the para-position does not bear a proton, cyclohexadienone diazeniumdiolates may be formed (Scheme 3.12) [145]. 

Analogously, 5-tributylstannylimidazole 29 was easily obtained from the regioselective deprotonation of 1,2-disubstituted imidazole 28 at C(5) followed by treatment with tributyltin chloride [24]. In the presence of 2.6 equivalents of LiCl, the Stille reaction of 29 with aryl triflate 30 afforded the desired 1,2,5-trisubstituted imidazole 31 with 2,6-di-tert-butyl-4-methylphenol (BHT) as a radical scavenger. Reversal of the nucleophile and electrophile of the Stille reaction also provided satisfactory results. For example, the coupling reaction of 5-bromoimidazole 33, derived from imidazole 32 via a regioselective bromination at C(5), and vinylstannane 34 produced adduct 35 [24],... 

Di-tert-butyl-4-methylphenol, production from butylenes, 4 425... 

The remarkably high isotope effects found in Reactions 10 and 10a are almost as embarrassing as was our discovery of an isotope effect of about 15 in the reaction with phenols referred to above. [For 2,6-di-tert-butyl-4-methylphenol in oxidizing styrene at 65°C. we obtained an isotope effect kH/kD = 10.6 (11). We have since carefully measured the isotope effect for 2,4,6-tri-ferf-butylphenol under the same conditions and have obtained a value 15. In these cases, hydrogen bonding to the solvent is relatively unimportant (6, 12). Similarly, DaRooge and Mahoney (9) have reported that for the reaction of 2,4,6-tri-tert-butylphenoxy radicals with 4-phenylphenol kH/kD 7.5.] Although... 

Fig. 18. NMR spectrum in CDCI3 of the poly(methyl methacrylate) (MnGpc=6900, Mw/Mn=1.13) obtained with the (TPP)AlSPr (1, X=SPr)-methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) system. [MMA]o/[l]o/[3e]o=30/1.0/0.5,100% conversion...

As mentioned above, the new method Lewis acid promoted living polymerization of methacrylic esters, by using enolatealuminum porphyrin (2) as nucleophilic initiator in conjunction with organoaluminum compounds, such as methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e), as Lewis acids has enabled us to synthesize poly(methacrylic ester) of narrow molecular-weight distribution [51]. On the other hand, some reactions of aluminum por-... 

Fig- 23. Polymerization of methacrylonitrile (MAN) with the living prepolymer of methy] methacrylate (MMA) (2)-methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) system in CH2CI2 at rt. Relationship between Mn of the PMAN block ( ) [Mw/Mn (O)] ol the polymer formed at 100% conversion and the initial monomer-to-initiator mole ratio ([MAN]o/[2]o)... 

Pyridine in place of methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) was also effective for the polymerization of MAN from the living PMMA (2). An example is shown by the polymerization of MAN under irradiation with the 2 (Mn=4000,Mw/Mn=1.09 prepared with [MMA]o/[l]o=40,100% conversion)-pyridine system at the initial mole ratio [MAN]q/[2] q/[pyridine]q of 100/1.0/0.6. MAN was polymerized up to 63% conversion in 65 h [Fig. 25 ( )], where the GPC peak of the polymer formed was observed to shift clearly towards the higher molecular-weight region (Mn=7600), retaining the narrow MWD (Mw/Mn=1.26), and the peak corresponding to the prepolymer of MMA was not observed. These facts clearly demonstrate the successful polymerization of MAN from 2, affording a PMMA-PMAN block copolymer. In sharp contrast to the polymerization of MAN, polymerization of MMA with aluminum porphyrin 2 was retarded by pyridine. For example, in the presence of 2 equiv of pyridine with respect to 2, the polymerization of 100 equiv of MMA proceeded very slowly to attain 25% conversion in 18 h under irradiation, while in the absence of pyridine, the polymerization of MMA with 2 was complete within 12 h under otherwise identical conditions. 

Fig. 33. Polymerization of 1,2-epoxypropane (PO) by the (Me4DBTAA)AlCl (12)-methylalu-minum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) system, [P0]o/[3e]o/[12]o=200/1.0/ 1.0, [12]o=71.4 mM, without solvent, rt. Time-conversion curve...

Fig. 36. Polymerization of propylene oxide (PO) initiated with the (TPP)AlCl (1, X=Cl)-2-propanol (2-PrOH) system in the presence of methylaluminum bis(2,6-di-tert-butyl-4-methylphenolate) (3e) ([2-PrOH]o/[PO]o/[l]o=9/200/l) in CH2CI2 at rt. Effect of the concentration of 3e on the rate of polymerization...

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