128-37-0Relevant academic research and scientific papers
Antioxidant Synergism Between Butylated Hydroxyanisole and Butylated Hydroxytoluene
Omura, Kanji
, p. 1565 - 1570 (1995)
Decay of the 2,6-di-tert-butyl-4-methylphenoxy radical in the presence of butylated hydroxyanisole (BHA) was investigated in 1,2-dimethoxyethane with or without triethylamine.BHT-radical was conveniently generated by dissociation of its unstable dimer in solution.The products were BHT, 3,3'-di-tert-butyl-5,5'-dimethoxy-2,2'-dihydroxybiphenyl (BHA-dimer), 2,6-di-tert-butyl-p-quinone methide (QM), 1,2-bis(3,5-di-tert-butyl-4-hydroxyphenyl)ethane, and 3,3',5,5'-tetra-tert-butyl-4,4'-stilbenequinone.The reaction without added triethylamine gave larger quantities of the last two products and BHA (recovery), whereas the reaction with it provided larger quantities of the first two products.The marked difference in the product distribution can be accounted for by a series of reactions including reversible dehydrogenation of BHA with BHT-radical, which generates 2-tert-butyl-4-methoxyphenoxy radical (BHA-radical) and BHT, reversible dimerization of BHA-radical, which affords an intermediary bis(cyclohexadienone), and spontaneous and base-catalysed prototropic rearrangement of the intermediate into BHA-dimer.Products of coupling between BHT-radical and BHA-radical were not obtained.BHA was found to undergo facile acid-catalyzed addition to QM, providing two isomeric bis(hydroxyphenyl)methanes.The results help to elucidate the mechanism of antioxidant synergism between BHA and BHT and may suggest that the synergism can be affected by base or acid. - Key words: Antioxidant synergism; butylated hydroxyanisole; butylated hydroxytoluene; effect of acid; effect of base; fate of phenoxy radicals involved.
Alkylation of p-cresol with tert-butyl alcohol using benign Bronsted acidic ionic liquid catalyst
Kondamudi, Kishore,Elavarasan, Pandian,Dyson, Paul J.,Upadhyayula, Sreedevi
, p. 34 - 41 (2010)
Novel and environmentally benign Bronsted acidic ionic liquids with SO3-H functionality were prepared using N-methyl imidazole, pyridine, triethylamine and 1,4-butanesultone as the source chemicals. The prepared ionic liquid catalysts were characterized by NMR and their catalytic activity in tert-butylation of p-cresol with tert-butyl alcohol (TBA) was investigated. The effects of reaction time, reaction temperature, reactant mole ratio and the recyclability of the catalysts on the conversion of p-cresol and selectivity to 2-tert-butyl-p-cresol (TBC) and 2,6-di-tert-butyl-p-cresol (DTBC) called butylated hydroxytoluene (BHT) were investigated. Lower alcohol to p-cresol mole ratios, lower ionic liquid to p-cresol ratio and temperature as low as 70 °C gave 80% conversion of p-cresol. The catalyst activity was found to be almost completely retained even after 5 recycles. Extended Arrhenius equation was used to calculate the rate constants for this reaction.
Bond Dissociation Enthalpy of α-Tocopherol and Other Phenolic Antioxidants
Lucarini, Marco,Pedulli, Gian Franco,Cipollone, Marta
, p. 5063 - 5070 (1994)
The equilibrium constants, K1, for the reaction between galvinoxyl and a series of phenolic antioxidants have been determined by means of EPR spectroscopy.With aroxyl radicals decaying at appreciable rates, K1 was obtained by performing kinetic analyses of the time dependence of the concentrations of the equilibrating radicals after mixing the reactants.In two cases the temperature dependence of K1 was also studied and the entropy change for the equilibration reaction was determined.Bond dissociation enthalpies, DH, of the ArO-H bond of the examined phenols were calculated by comparison with the known value of 2,4,6-tri-tert-butylphenol (81.24 kcal mol-1).A larger than expected DH value was found for probucol (81.03 kcal mol-1) and an explanation of this behavior was given in terms of the preferred conformation adopted by the para alkylthio group.The DH value of α-tocopherol (78.93 kcal mol-1) was found to be very close to that of the phenolic precursor of galvinoxyl (78.80 kcal mol-1) and somewhat larger than that of 2,6-di-tert-butyl-4-methoxyphenyl (77.61 kcal mol-1).
Identification of Degradation Products of Terbutol in Environmental Water from Golf Courses
Suzuki, Toshinari,Yaguchi, Kumiko,Ohnishi, Kazuo,Suga, Tetsuya
, p. 1712 - 1717 (1995)
Degradation products of terbutol (2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate) in drainage and ground water from golf courses, on which terbutol had been applied as a herbicide, were identified by capillary GC/MS and reversed-phase HPLC. terbutol and 4-carboxy-, N-demethyl-, and 4-carboxy-N-demethylterbutol were detected in all water samples at concentrations of parts per billion levels.In addition, 4-(hydroxymethyl)- and 4-formylterbutol, 2,6-di-tert-butyl-4-methylphenol (BHT), and 4-(hydroxymethyl)-, 4-formyl-, and 4-carboxy-BHT were observed in some water samples at concentrations of parts per thousand levels.These results demonstrated that terbutol applied on golf courses was mainly degraded by N-demethylation, oxidation of the 4-methyl group, and hydrolysis of the carbamate ester linkage. Keywords:Terbutol; 2,6-di-tert-butyl-4-methylphenyl N-methylcarbamate; identification; degradation
Synthesis, characterization and investigation of catalytic activity of Cu1-xCoxFe2O4 nanocatalysts in t-butylation of p-cresol
Alamdari, Reza Fareghi,Hosseinabadi, Zahra,Khouzani, Masoud Farhadi
, p. 827 - 834 (2012)
In this work, tertiary butylation of p-cresol was carried out in the presence of Cu1-xCoxFe2O4 (x = 0 to 1) nanocatalysts by employing methyl-tert-butyl ether (MTBE) and tert-butyl alcohol (TBA) as alkylation agents. Effects of temperature, mole ratio, type and catalyst composition, time and solvent in reaction conditions were investigated. These nanocatalysts were synthesized using hydrothermal method. The characterization of these catalysts was investigated by means of X-ray diffraction (XRD), Scanning Electron Microscopy (SEM) and Fourier Transform Infrared (FT-IR). These nanocatalysts can be recovered and recycled. A good correlation was found between the activity, in terms of p-cresol conversion and various product selectivities for this reaction, and also the acid-base properties of the catalysts. Nano-sized Cu0.5Co0.5Fe 2O4, in comparison to the other nanocatalysts discussed in this report is the most active nanocatalyst. The only product of this reaction is 2-t-butyl p-cresol with selectivity of 100% and p-cresol conversion is 70%. The possible mechanism for this reaction system was discussed based on the reaction results. The reaction mechanism proposed involves the interaction of phenoxide from phenol and the tert-butyl cation from isobutene on Cu 1-xCoxFe2O4. Indian Academy of Sciences.
Multi SO3H supported on carbon nanotubes: A practical, reusable, and regioselective catalysts for the tert-butylation of p-cresol under solvent-free conditions
Fareghi-Alamdari, Reza,Golestanzadeh, Mohsen,Zekri, Negar,Mavedatpoor, Zeinab
, p. 537 - 549 (2015)
The present study describes the synthesis, characterization, and catalytic activity of sulfonated multi-walled carbon nanotubes and sulfonated single-walled carbon nanotubes in the tert-butylation of p-cresol. The catalysts were prepared using a chemical and simple process and it characterized by scanning electron microscopy, Fourier transform infrared, and Raman spectroscopy, thermogravimetric analysis, and acid-base titration. The sulfonated multi-walled carbon nanotubes and sulfonated single-walled carbon nanotubes have been used as practical heterogeneous catalytic systems in the tert-butylation of p-cresol under solvent-free conditions. Sulfonated multi-walled carbon nanotubes with the highest total density of SO3H groups possessed high activity for p-cresol conversion and high selectivity than the sulfonated single-walled carbon nanotubes. This methodology offers some advantages of high selectivity, and high yields, easy work-up, solvent-free conditions, and reusable catalyst. Moreover, the catalytic system was used in scale-up under similar optimized reaction conditions.
Alkylation of Phenols with tert-Butanol Catalyzed by H-Form of Y Zeolites with a Hierarchical Porous Structure
Bayguzina,Makhiyanova,Khazipova,Khusnutdinov
, p. 1554 - 1559 (2019)
tert-Butyl-substituted phenols have been synthesized via the reaction of phenol, o-, m-, and p-cresols with tert-butanol under the action of CBr4-promoted Y-zeolites in the H-form with a hierarchical porous structure.
Hydrolysis of isobutylaluminum aryloxides studied by 1H NMR and quantum chemical methods
Faingol’d,Zharkov,Bravaya,Chernyak
, p. 1958 - 1965 (2016)
The results of 1H NMR and quantum chemical studies of hydrolysis of isobutylaluminum aryloxides are presented. According to the data of 1H NMR spectroscopy, the hydrolysis of monomeric diisobutylaluminum aryloxides (2,6-Bu2 t—C6H3O)AlBu2 i and (2,6-Bu2 t,4-Me—C6H2O)AlBu2 i occurs selectively at the Al—OAr bond to form the corresponding sterically bulky phenol and polyisobutylaluminoxane. At the molar ratios Al: H2O = 2, the formed sterically bulky phenol reacts slowly with diisobutylaluminum monoaryloxide to form isobutylaluminum diaryloxide. Dimeric aryloxide [(2-But—C6H4O)AlBu2 i]2 is not hydrolyzed under similar conditions. The quantum chemical calculations confirmed the experimental results: the hydrolysis at the Al—OAr bond has a lower energy barrier than that at the Al—C bond because of the formation of HH2O…OO?Ar hydrogen bonds.
Phenol-Phenoxyl Radical Equilibria by Electron Spin Resonance: are Radicals derived from Tocopherol and Analogues Exceptionally Stabilized?
Jackson, Richard A.,Hosseini, Kamran Mousavi
, p. 967 - 968 (1992)
The extra 'stabilization' of the 2,2,4,6,7,-pentamethyl-2,3-dihydrobenzofuran-5-oxyl radical compared with the 2,6-di-tert-butyl-4-methoxyphenoxyl radical is attributed to entropy differences between the parent phenols.
KINETICS OF THE REACTION OF 2,6-DI-t-BUTYLPHENOL WITH METHYL ACRYLATE IN THE PRESENCE OF POTASSIUM 2,6-DI-t-BUTYLPHENOLATE AND THE EFFECT OF PROTON-DONOR COMPONENTS ON THE MECHANISM OF THIS REACTION
Volod'kin, A. A.
, p. 877 - 883 (1991)
A kinetic scheme is proposed for the reaction of 2,6-di-t-butylphenol with methyl acrylate in the presence of potassium 2,6-di-t-butylphenolate.Rate constants have been calculated for the elementary stages which describe the mechanism of catalysis and the effect on the kinetic laws of the proton-donor components 2,6-di-t-butylphenol, water, and methanol.The kinetic scheme contains 30 components and includes 62 rate constants for the elementary stages, which were calculated by mathematical modeling of the kinetics of the process.The calculated results are compared with experimental data for the dependence of the rate of consumption of 2,6-di-t-butylphenol on the concentration of potassium 2,6-di-t-butylphenolate and on the concentrations of the proton-donor components.
