- High thermo-responsive shape memory epoxies based on substituted biphenyl mesogenic with good water resistance
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In this work, a novel epoxy monomer denoted as 3,5′-di-t-butyl-5,3′-dimethyl biphenyl diglycidyl ether (t-BuMBPDGE) was synthesized and applied into in situ composites with 3,3′,5,5′-tetramethyl-4,4′-biphenyl diglycidyl ether (TMBPDGE), accompanied with curing agent aromatic amines. The liquid crystalline phase structure and the crosslink density of substituted biphenyl epoxies were determined by polarized optical microscopy, wide angle X-ray diffraction measurements and dynamic storage moduli data. The samples showed good mechanical properties and could recover quickly from a second state to their initial states with a shape fixity ratio higher than 98% and shape recovery ratio higher than 99%, owing to the oriented structure and increased crosslink network density caused by the orientation of biphenyl mesogenic. The high glass transition temperatures ranging from 160 to 178 °C and good water resistance could contribute to a stable fixed shape. The water resistance is analyzed by contact angles test. The samples exhibited contact angles of 92-98 degrees, which indicated that the water resistance was apparently better than that of conventional epoxy systems.
- Guo, Huilong,Li, Yinwen,Zheng, Jian,Gan, Jianqun,Liang, Liyan,Wu, Kun,Lu, Mangeng
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- Selective c-c coupling reaction of dimethylphenol to tetramethyldiphenoquinone using molecular oxygen catalyzed by cu complexes immobilized in nanospaces of structurally-ordered materials
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Two high-performance Cu catalysts were successfully developed by immobilization of Cu ions in the nanospaces of poly(propylene imine) (PPI) dendrimer and magadiite for the selective C-C coupling of 2,6-dimethylphenol (DMP) to 3,3′,5,5′-tetramethyldiphenoquinone (DPQ) with O2 as a green oxidant. The PPI dendrimer encapsulated Cu ions in the internal nanovoids to form adjacent Cu species, which exhibited significantly high catalytic activity for the regioselective coupling reaction of DMP compared to previously reported enzyme and metal complex catalysts. The magadiite-immobilized Cu complex acted as a selective heterogeneous catalyst for the oxidative C-C coupling of DMP to DPQ. This heterogeneous catalyst was recoverable from the reaction mixture by simple filtration, reusable without loss of efficiency, and applicable to a continuous flow reactor system. Detailed characterization using ultraviolet-visible (UV-vis), Fourier transform infrared (FTIR), electronic spin resonance (ESR), and X-ray absorption fine structure (XAFS) spectroscopies and the reaction mechanism investigation revealed that the high catalytic performances of these Cu catalysts were ascribed to the adjacent Cu species generated within the nanospaces of the PPI dendrimer and magadiite.
- Maeno, Zen,Mitsudome, Takato,Mizugaki, Tomoo,Jitsukawa, Koichiro,Kaneda, Kiyotomi
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- Synthesis method of 3,3',5,5'-tetraalkyl-4,4'-diphenoquinone
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The invention provides a synthesis method of 3,3',5,5'-tetraalkyl-4,4'-diphenoquinone. 2,6-dialkyl phenol is dissolved in a reaction solvent; a copper ion loaded hydrophobic modified resin catalyst and an oxidizing agent are added; reaction is performed for 2 to 8h at 40 DEG C to 80 DEG C; filtering is performed to obtain filter liquid; then, the filter liquid is distilled; distillation residues are cleaned by alkanol; after the drying, the 3,3',5,5'-tetraalkyl-4,4'-diphenoquinone is obtained. The synthesis method is simple; after being recovered, the catalyst can be repeatedly used; the reaction selectivity is high; the yield of the 3,3',5,5'-tetraalkyl-4,4'-diphenoquinone can reach 95 percent or higher; no by-product of polyphenyl ether is generated; the copper ion content is smaller than 5mu g/g; the product purity is greater than or equal to 99.5 percent.
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Paragraph 0090; 0091; 0092
(2017/08/29)
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- Efficient oxidative coupling of 2,6-disubstituted phenol catalyzed by a dicopper(II) complex
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Complexation of a rigid multi-pyridine ligand bis(2-pyridyl)-1,8- naphthyridine (bpnp) with [Cu2(TFA)4] (TFA = trifluoroacetate) resulted in the formation of a dinuclear copper(ii) complex, namely [Cu2(bpnp)(μ-OH)(TFA)3] (1). This complex has been characterized by X-ray crystallographic, spectroscopic and elemental analyses. Complex 1 is an efficient catalyst for the oxidative coupling of various 2,6-disubstituted phenols with molecular oxygen. Yields and selectivity depend on the reaction conditions employed, the best results being obtained in isopropanol or dioxane at 90 °C with yields of >99%. Mechanistic pathway of the catalysis is discussed.
- Liao, Bei-Sih,Liu, Yi-Hung,Peng, Shei-Ming,Liu, Shiuh-Tzung
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scheme or table
p. 1158 - 1164
(2012/03/07)
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- PREPARATION OF BIPHENOLS BY OXIDATIVE COUPLING OF ALKYLPHENOLS USING A RECYCLABLE COPPER CATALYST
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A method for producing biphenols by oxidative coupling of dialkylphenols which proceeds in two stages is disclosed, using a copper-amine complex which is catalytically active in each stage. A novel copper-amine complex is also disclosed which exhibits high catalytic activity for the oxidative coupling of substituted phenols under mild conditions, has dual (two stage) activity, and can be readily recycled and reused.
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- Oxidative coupling of some 2,6-disubstituted phenol derivatives in perchloric acid mediated by cerium(IV) ions
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2,6-Disubstituted phenol derivatives have been oxidized by cerium(IV) perchlorate in aqueous or aqueous-acetonitrile solutions of perchloric acid as well as in two-phase systems to the corresponding 1,4-benzoquinones, 4,4′-diphenoquinones, and oligomeric
- Domagala, Slawomir,Steglinska, Violetta,Dziegiec, Jozef
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p. 761 - 768
(2007/10/03)
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- Electron Transfer and Contact Ion Pair Formation, 42. Cyclovoltammetric and ESR/ENDOR Investigations of the One-Electron Reduction of Diphenoquinones
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Semiquinone radical anions are prototype compounds for contact ion pair formation with metal counter cations.In order to investigate the still open question whether bulky alkyl groups can sterically interfere, diphenoquinone derivatives O=C(RC=CH)2C=C(HC=CR)2C=O with R = C(CH3)3, CH(CH3)2 and CH3 have been selected and the following ESR/ENDOR results are obtained for the alkaline metal cations: The tetrakis(tert-butyl)-substituted radical anion only adds Li(+) and Na(+), while K(+) forms no ion pair.The 3,3',5,5'-tetra(isopropyl)diphenoquinone radical anion is accessible to all cations Me(+), although Rb(+) and Cs(+) seem to be present solvent-separated in solution.The tetramethyl-substituted radical anion unfortunately polymerizes rapidly.Additional information concerns the ESR/ENDOR proof for ion triple radical cation formation (.+), or the difference in the coupling constants upon Me(+) docking at one δ(-)O=C group, suggesting that about 87percent of the spin density is located in the cation-free molecular half of the diphenoquinone radical anion.Based on the wealth of ESR/ENDOR information, crystallization of the contact ion pairs and their structural charecterization should be attempted. - Keywords: One-Electron Reduction of Diphenoquinones; Cyclovoltammetry; ESR/ENDOR Spectra; Contact Ion Pairs and Triples
- John, Andreas,Bock, Hans
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p. 1699 - 1716
(2007/10/03)
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- Oxidation by Cobalt(III) Acetate. Part 13. Oxidation of Substituted Phenols with Cobalt(III) Acetate in Acetic Acid
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The oxidation of 2,6-di- and 2,4,6-tri-substituted phenols with cobalt(III) acetate has been investigated in acetic acid under an inert atmosphere; the former gave the corresponding diphenoquinones in excellent yields, and the latter yielded side-chain or nuclear acetoxylated products in moderate to good yields.
- Hirano, Masao,Ishii, Tadamichi,Morimoto, Takashi
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p. 1434 - 1436
(2007/10/02)
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- Mushroom tyrosinase catalysed coupling of hindered phenols: A novel approach for the synthesis of diphenoquinones and bisphenols
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An efficient oxidative carbon-carbon coupling of hindered phenols leading to diphenoquinones and bisphenols by mushroom tyrosinase is reported.
- Pandey,Muralikrishna,Bhalerao
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p. 3771 - 3774
(2007/10/02)
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