128-38-1Relevant articles and documents
Magnetic Field Effects on the Catalytic Oxidation of 2,6-Di-tert-butylphenol by CoSMDPT: 2H and 17O Magnetic Isotope Effects
Perito, Richard P.,Corden, Barry B.
, p. 3472 - 3477 (1988)
The effect of a magnetic field between 0 and 70 kG on the catalytic oxidation rate of 2,6-di-tert-butylphenol, DTBP, to form 2,6-di-tert-butylquinone, BQ, by cobalt(II) bis(3-(salicylideneamino)propyl)methylamine, CoSMDPT, in the presence of O2 is reported.No kinetic 2H isotope effect is observed with DTBP-OD, and DTBP-4-d1-OD exhibits mass and magnetic kinetic isotope effects of 1.25 and 1.22, respectively.In the presence of additive phenol, CoSMDPT catalyzes the formation of 2,2',6,6'-tetra-tert-butyldiphenoquinone, DPQ.The mass and magnetic isotope effects in DPQ formation are negligible for the deuteration of the phenolic position.DTBP-4-d1-OD in the presence of phenol-OD exhibits kinetic mass and magnetic 2H isotope effects in DPQ formation of 1.73 and 1.31, respectively.These results are compared to the oxidation rate of DTBP by Pb(OAc)4, which is unaffected by a 0-70-kG magnetic field and has a 2H kinetic isotope effect of 1.28 for DTBP-4-d1-OD.A significant 17O magnetic isotope effect is observed only for BQ production.The 17O enrichment of BQ given has an overall enrichment factor, S(f)=1.76, at 9percent DTBP conversion.These results are discussed in terms of a proposed mechanism.
Novel photochemical coupling of hindered phenols in the presence of acridine mechanistically probed by CIDEP
Okada, Keiji,Okubo, Katsura,Oda, Masaji,Murai, Hisano
, p. 845 - 846 (1995)
Irradiation of hindered phenols in the presence of acridine as a light absorber gives bisphenols and biacridane.CIDEP study establishes the path of hydrogen abstraction by the triplet acridine.The overall mechanism is proposed by the product analysis and the CIDEP studies.
Liquid-phase oxidation of 2,6-di-tert-butylphenol with Cu-impregnated MCM-41 catalysts in the presence of alkali metals
Fujiyama, Hirofumi,Kohara, Ichitaro,Iwai, Keisuke,Nishiyama, Satoru,Tsuruya, Shigeru,Masai, Mitsuo
, p. 417 - 425 (1999)
Mesoporous silicate MCM-41, with a uniform pore diameter of ca. 35 A, was used as a support for impregnated Cu catalysts for liquid-phase oxidation of 2,6-di-tert-butylphenol (BOH) in the presence of a base such as KOH. The oxidation products were 4,4′-dihydroxy-3,3′,5,5′-tetra-tert-butyl-biphenyl (H2DPQ) and 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone (DPQ). An alkali such as a potassium salt, which promotes the phenol oxidation activity of copper ion-impregnated MCM-41 (Cu/MCM-41) catalyst, was found to be more effective as an additive to the reaction solution than impregnation on the Cu/MCM-41 catalyst. The added alkali was found to play a role in generating the corresponding phenolate anion by dissolving a BOH molecule. H2DPQ is formed through tautomerization of an intermediate dimer obtained by the C-C coupling of the corresponding phenoxy radicals. DPQ is formed via the consecutive oxidation of H2DPQ and/or via the oxidative dehydrogenation of the intermediate dimer. The BOH molecules in the mesopores of Cu/MCM-41, rather than the BOH in bulk solution in the presence of CuCl2, were found to favor H2DPQ production. Cu/MCM-41 with added potassium [(K-Cu)/MCM-41] was much more active for phenol oxidation than Cu-impregnated NaZSM-5 with added potassium [(K-Cu)/NaZSM-5] or the corresponding NaY [(K-Cu)/NaY], each catalyst having only uniform micropores. This result indicates that the oxidation of sterically bulky BOH occurs mainly at the active sites in the mesopores and is difficult to carry out in the micropores of (K-Cu)/NaZSM-5 and (K-Cu)/NaY zeolites because of the steric bulkiness of the oxidation products, H2DPQ and DPQ. The liquid-phase adsorption amounts of BOH on NaZSM-5 and NaY were found to be comparable to that on MCM-41. The shape selectivity by the oxidation products in the micropores of (K-Cu)/NaZSM-5 and (K-Cu)/NaY zeolites was thus suggested to inhibit the BOH oxidation activities of both catalysts, based on the results of the oxidation reaction and liquid-phase adsorption of BOH.
Electrooxidative Coupling of Phenols. I. Product-Selective Electrosynthesis of 2,2',6,6'-Tetra-tert-butyl-1,1'-biphenol from 2,6-Di-tert-butylphenol
Torii, Sigeru,Dhimane, Anne-Lise,Araki, Yoshitaka,Inokuchi, Tsutomu
, p. 2105 - 2108 (1989)
Biphenol electrosynthesis is achieved in a divided cell by a set of redox reactions from 2,6-di-tert-butylphenol (4) via the corresponding diphenoquinone 3.Phenol 4 can also lead to either the corresponding biphenol 2 or diphenoquinone 3 in a product-selective manner by electrooxidation in an undivided cell.The choice of solvent is a crucial factor for the product-selectivity.
Reduction of 4,4′-stilbenequinone and 4,4′-diphenoquinone upon reaction with photogenerated radicals
Goerner, Helmut
, p. 1202 - 1207 (2010)
The properties of 3,3′,5,5′-tetra-tert-butyl-4,4′- stilbenequinone (StQ) were studied by photochemical means. Acetone, acetophenone or benzophenone was photolyzed in the presence of both StQ and a donor, such as alcohols or triethylamine. This initiated reaction of a ketyl radical with StQ to form a semiquinone radical and eventually induce a permanent bleaching due to conversion of StQ to 4,4′-dihydroxystilbene (StQH2). The quantum yield of conversion of StQ to StQH2 increases with the donor concentration. Similar effects were found for the ketone-sensitized radical-induced conversions of the analogous diphenoquinone to the reduction product, diphenol.
Clean synthesis of 3,3′,5,5′-Tetra-tert-butyl-4,4′-diphenoquinone from the oxidative coupling of 2,6-Di-tert-butylphenol catalyzed by alkali-promoted Cu-Mg-Al hydrotalcites in the presence of molecular oxygen
Iwai, Keisuke,Yamauchi, Takayoshi,Hashimoto, Keiji,Mizugaki, Tomoo,Ebitani, Kohki,Kaneda, Kiyotomi
, p. 58 - 59 (2003)
2,6-Di-tert-butylphenol is selectively transformed to 3,3′,5,5′-tetra-tert-butyl-4,4′-diphenoquinone in the presence of molecular oxygen using alkali-promoted Cu-Mg-Al hydrotalcites as recyclable heterogeneous catalysts.
Chromium-Salen Catalyzed Cross-Coupling of Phenols: Mechanism and Origin of the Selectivity
Nieves-Quinones, Yexenia,Paniak, Thomas J.,Lee, Young Eun,Kim, Sun Min,Tcyrulnikov, Sergei,Kozlowski, Marisa C.
, (2019)
A highly chemoselective phenol cross-coupling reaction catalyzed by a Cr-salen catalyst was developed. Kinetic studies showed that the oxidation of Cr(III) to Cr(V) is the rate-determining step of the reaction. In addition, experimental stoichiometric analysis showed that a high valent Cr(V) species is the active catalyst for this process. The selectivity of the reaction was found to be determined by the cross-coupling carbon-carbon bond forming reaction, rather than any precoordination species. It appears that the lowest energy cross-coupling pathway requires a lesser degree of electronic reorganization in its transition state vs the lowest energy homocoupling pathway. This result was supported by stoichiometric Cr(V) kinetics, 13C kinetic isotope effects, and density functional theory (DFT) calculations. The understanding of the full landscape of this reaction allowed us to develop a general analysis to predict the regioselectivity of the cross-coupling reaction.
Formation of 3,3',5,5'-tetra(tert-butyl)diphenoquinone and 3,3',5,5'-tetra(tert-butyl)-4,4'-dihydroxybiphenyl in the reaction of 2-(acetylamino)-3-[3',5'-di(tert-butyl)-4'-hydroxyphenyl]propanoic acid with thionyl chloride
Volod'Kin,Kurkovskaya,Zaikov,Lomakin
, (2013)
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Catalytic oxidation of hindered phenols by a copper(I) complex and dioxygen
Gupta,Mukherjee
, p. 7763 - 7767 (2000)
The dioxygen reaction product of a binuclear copper(I) complex of a new m-xylyl-based ligand has proven to be a catalyst in the promotion of oxidative carbon-carbon coupling of hindered phenols, which leads to bisphenol and diphenoquinones. (C) 2000 Elsevier Science Ltd.
Oxidation of 2,6-di-tert-butylphenol by tetrapyridyl oxoiron(IV) complex
Lakk-Bogáth, Dóra,Speier, Gábor,Kaizer, József
, p. 227 - 230 (2018)
The reactivity of the previously reported pentadentate low-spin (S = 1) oxoiron(IV) complex, [FeIV(O)(asN4Py)] (2) (asN4Py = N,N-bis(2-pyridylmethyl)-1,2-di(2-pyridyl)ethylamine), has been investigated in the oxidation reaction of 2,6-di-tert-butylphenol derivatives. Detailed kinetic, and mechanistic studies (kinetic isotope effect (KIE) of 4.52, and Hammett correlation with ρ = ?1.83), lead to the conclusion that the rate-determining step in this reaction involves direct hydrogen-atom transfer (HAT) from the phenol by the oxoiron(IV) species, in contrast to the heme-type horseradish peroxidase (HRP) system.
Selective Formation of 4,4′-Biphenols by Anodic Dehydrogenative Cross- and Homo-Coupling Reaction
Dahms, Benedikt,Kohlpaintner, Philipp J.,Wiebe, Anton,Breinbauer, Rolf,Schollmeyer, Dieter,Waldvogel, Siegfried R.
, p. 2713 - 2716 (2019)
A simple and selective electrochemical synthesis by dehydrogenative coupling of unprotected 2,6- or 2,5-substituted phenols to the desired 4,4′-biphenols is reported. Using electricity as the oxidizing reagent avoids pre-functionalization of the starting materials, since a selective activation of the substrates takes place. Without the necessity for metal-catalysts or the use of stoichiometric reagents it is an economic and environmentally friendly transformation. The elaborated electrochemical protocol leads to a broad variety of the desired 4,4′-biphenols in a very simplified manner compared to classical approaches. This is particular the case for the cross-coupled products.
A dual-functional heterogeneous ruthenium catalyst for the green one-pot synthesis of biphenols
Maeno, Zen,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro
, p. 3205 - 3209 (2017)
A green one-pot synthesis of biphenols using O2 and H2 was achieved using a magadiite-supported Ru nanoparticle catalyst. This catalyst selectively promoted the oxidative coupling of phenols to diphenoquinones with O2, followed by the successive reduction of these diphenoquinones to biphenols using H2 in a single reactor.
Stoichiometric Formation of an Oxoiron(IV) Complex by a Soluble Methane Monooxygenase Type Activation of O2 at an Iron(II)-Cyclam Center
Kass, Dustin,Corona, Teresa,Warm, Katrin,Braun-Cula, Beatrice,Kuhlmann, Uwe,Bill, Eckhard,Mebs, Stefan,Swart, Marcel,Dau, Holger,Haumann, Michael,Hildebrandt, Peter,Ray, Kallol
supporting information, p. 5924 - 5928 (2020/05/08)
In soluble methane monooxygenase enzymes (sMMO), dioxygen (O2) is activated at a diiron(II) center to form an oxodiiron(IV) intermediate Q that performs the challenging oxidation of methane to methanol. An analogous mechanism of O2 activation at mono-or dinuclear iron centers is rare in the synthetic chemistry. Herein, we report a mononuclear non-heme iron(II)-cyclam complex, 1-trans, that activates O2 to form the corresponding iron(IV)-oxo complex, 2-trans, via a mechanism reminiscent of the O2 activation process in sMMO. The conversion of 1-trans to 2-trans proceeds via the intermediate formation of an iron(III)-superoxide species 3, which could be trapped and spectroscopically characterized at-50 °C. Surprisingly, 3 is a stronger oxygen atom transfer (OAT) agent than 2-trans; 3 performs OAT to 1-trans or PPh3 to yield 2-trans quantitatively. Furthermore, 2-trans oxidizes the aromatic C-H bonds of 2,6-di-tert-butylphenol, which, together with the strong OAT ability of 3, represents new domains of oxoiron(IV) and superoxoiron(III) reactivities.
