- Novel oxidation reactions of sterically demanding 3,6-di-tert-butyl porphyrin-o-quinones to muconic anhydride derivatives
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Porphyrin quinones with sterically demanding 3,6-di-tert-butyl-o-quinones were synthesized for electron transfer studies. In the presence of atmospheric oxygen the covalently free base porphyrin-o-quinones are oxidized to muconic acid anhydride and 3,6-di
- Speck, Marcus,Senge, Mathias O.,Schaefer, Andreas,Kurreck, Harry
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- Synthesis of titanium(iv) 3,6-di-tert-butylcatecholate complexes
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Two synthetic approaches were used for the synthesis of 3,6-di-tert-butylcatecholate derivatives of titanium(iv). These approaches are based on the exchange reaction between sodium catecholate and titanium(iv) chloride and the reaction of 3,6-di-tert-buty
- Meshcheryakova,Shavyrin,Cherkasov,Piskunov
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- Intramolecular London Dispersion Interactions Do Not Cancel in Solution
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We present a comprehensive experimental study of a di-t-butyl-substituted cyclooctatetraene-based molecular balance to measure the effect of 16 different solvents on the equilibrium of folded versus unfolded isomers. In the folded 1,6-isomer, the two t-bu
- Schümann, Jan M.,Wagner, J. Philipp,Eckhardt, André K.,Quanz, Henrik,Schreiner, Peter R.
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- Hydroxylation of substituted diatomic phenols and their derivatives
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Oxidation of 3,6-di-tert-butylpyrocatechol in protic media is accompanied by the formation of 3,6-di-tert-butyl-2-hydroxy-para-benzoquinone. Hydroxylation of the 3,5-isomer results in dealkylation and isomerization with the formation of 6-tert-butyl-2-hydroxypora-benzoquinone and the quinone mentioned above, respectively. Their ratio depends on the nature of the solvent. Analogous processes accompany redox transformations of 2,6-di-tert-butylhydroquinone, 2,6-diphenyl-para-benzoquinone, and 2,4,6-tri-tert-butylphenol adsorbed on silica gel. Derivatives of 3,5-substituted pyrocatechols formed under conditions of heterophase oxidation in air are capable of transformations to form nitrogen-containing compounds.
- Vol'eva,Prokof'eva,Belostotskaya,Komissarova,Ershov
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- Heterospin biradicals based on new piperidineoxyl-substituted 3,6-di-tert-butyl-o-benzoquinone
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A nucleophilic addition reaction of 4-hydroxy-2,2,6,6-tetramethylpiperidine-1-oxyl (OH-TEMPO) to 3,6-di-tert-butyl-o-benzoquinone was used to obtain a new sterically hindered o-benzoquinone (1) containing 2,2,6,6-tetramethylpiperidineoxyl functional group, which was characterized by IR spectroscopy, mass spectrometry, elemental analysis, and X-ray diffraction. A one-electron reduction of 1 with potassium and thallium is an efficient method for the generation of earlier unknown heterospin biradicals 5a and 5b, respectively, containing nitroxide and o-semiquinone radical centers. Analysis of the hyperfine structure of the ESR spectra of biradicals 5a and 5b in solution showed that they belong to the group of heterospin biradicals with strong (J >> a) and fast exchange interaction between the radical centers.
- Egorova,Druzhkov,Kozhanov,Cherkasov,Cherkasov
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p. 1629 - 1635
(2018/01/01)
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- Synthesis and use of ortho-(branched alkoxy)-tert-butoxybenzenes
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A series of sterically hindered o-(branched alkoxy)-tert-butoxybenzenes was efficiently prepared in good yields owing to a new practical and simple preparation of o-tert-butoxyphenol starting from catechol and isobutene. Use of DMF di-tert-butyl acetal reagent instead of isobutene/H2SO 4 (cat.) for O-tert-butylation was very convenient in case of ortho bulky phenols affording the corresponding tert-butyl ethers in high yield and purity. This general route proved to be useful since no reliable access was available to o-di-t-BuO-substituted arenes. Application to the synthesis of congested phosphorus-based compounds is presented.
- Rast, Slavko,Stephan, Michel,Mohar, Barbara
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supporting information
p. 6815 - 6818
(2013/01/15)
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- Alkoxylation of 3,6-Di-tert-butyl-1,2-benzoquinone. New Bis-1,2-benzoquinones
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Alkoxylation of 3,6-di-tert-butyl-1,2-benzoquinone with a number of diols, including propane-1,3- diol, butane-1,4-diol, di-, and triethylene glycols, and cyclohexane-1,4-diyldimethanol, was studied. Nine new 4-alkoxy-3,6-di-tert- butyl-1,2-benzoquinones were synthesized, four of which were bis-1,2-benzoquinones with different tethers (6-13 atoms) between the quinone fragments. Depending on the length of the chain between the hydroxy groups in glycols, bicyclic 4,5-disubstituted 3,6-di-tert-butyl-1,2-benzoquinones were formed or their stepwise alkoxylation occurred. The newly synthesized o-benzoquinone derivatives can be reduced with alkali metals to give radical anions and converted into semiquinone chelates with manganese carbonyl. Pleiades Publishing, Ltd., 2011.
- Shurygina,Druzhkov,Arsen'ev,Bubnov,Fukin,Chesnokov,Cherkasov
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experimental part
p. 486 - 495
(2011/07/08)
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- Alkylation of pyrocatechol in tert-butyl alcohol-sulfuric acid-benzene
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Alkylation of pyrocatechol with tert-butyl alcohol in benzene in the presence of sulfuric acid gave 3,5-di-tert-butylbenzene-1,2-diol in a higher yield than in analogous reaction with tert-butyl alcohol. This result was rationalized by reduction of inhibitory effect of liberated water, formation of heterogeneous system, and occurrence of the alkylation process in nonpolar organic phase. Intermediate products were identified and found to undergo intra- and intermolecular tert-butyl group transfer with formation of more stable 3,5-di-tert-butylbenzene-1,2-diol. The formation of p-di-tert-butylbenzene indicated participation of benzene in crossalkylation processes. Pleiades Publishing, Ltd., 2011.
- Vol'eva,Prokof'eva,Belostotskaya,Komissarova,Gorbunov,Kurkovskaya
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body text
p. 1310 - 1312
(2011/12/05)
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- o-benzoquinone photoreduction products in the presence of N,N-dimethylanilines
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Photoreduction of o-benzoquinones in the presence of para-substituted N,N-dimethyl-anilines under irradiation at λ ≥ 500 nm affords pyrocatechol monoethers of the 2-(amino-methoxy)phenol type. In the subsequent dark reaction, these monoethers undergo quantitative decomposition by a heterolytic mechanism to give the corresponding pyrocatechols and nitrogen-containing compounds. The rate of this decomposition decreases with decreasing size of the substituent at the position adjacent to the ether bond that is formed upon photoreduction. The redox characteristics of such pyrocatechol monoethers can serve as the criterion of their stability. A weakening of the electron-withdrawing properties of quinones and the electron-donating properties of amines leads to an increase in stability of their reaction products.
- Shurygina,Kurskii,Chesnokov,Druzhkov,Fukin,Abakumov,Cherkasov
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p. 1585 - 1592
(2008/02/08)
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- Photoreduction of o-benzoquinones in the presence of p-bromo-N,N- dimethylaniline
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Photoreduction of o-benzoquinones in the presence of p-bromo-N,N- dimethylaniline under irradiation (λ, > 500 nm) affords the corresponding pyrocatechols and hydroxyphenyl ethers. The latter are unstable and, in turn, decompose in the dark reaction to pyrocatechols. The ratio between pyrocatechol and hydroxyphenyl ether formed upon the photoreaction is determined by the structure of o-quinone, namely, the presence and bulk of substituents in positions 3 and 6 of the ring. The yield of pyrocatechol is maximal (60-65%) if the substituents are the same (H and H, But and But) or insignificantly differ (Pri and But), regardless of its bulk.
- Chesnokov,Cherkasov,Abakumov,Kurskii,Shurygina,Mamysheva,Shavyrin
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p. 718 - 724
(2007/10/03)
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- REDOX REACTIONS OF 3,6-DI-TERT-BUTYL-ORTHO-BENZOQUINONE, CATALYZED BY TETRAFLUOROSILANE
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Tetrafluorosilane-catalyzed redox reactions of 3,6-di-tert-butyl-ortho-benzoquinone have been examined.From the EPR spectroscopic data and a study of the reaction products, a mechanism for these reactions is proposed involving the formation of a quinone-tetrafluorosilane complex which has strong oxidizing properties, and which enables the original quinone to undergo further reactions.
- Chekalov, A. K.,Gvazava, N. G.,Vol'eva, V. B.,Prokof'eva, T. I.,Prokof'ev, A. I.,Ershov, V. V.
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p. 991 - 993
(2007/10/02)
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- ON THE PREPARATION AND PSEUDOROTATION OF CERTAIN MONOCYCLIC PENTAOXYPHOSPHORANES
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The S-bridged pentaoxyphosphorane 2a has been prepared for the first time and its ground-state structure studied on the time scale of NMR (1H, 19F, 31P, and 13C) spectroscopic measurements.Compound 2a was found to show significant barriers to intramolecular ligand rearrangement (pseudorotation).A comparative study on non-bridged pentaoxyphosphoranes of type 14 was also undertaken.
- Abdou, W. M.,Mahran, M. R.
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p. 119 - 128
(2007/10/02)
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