- PHOTOCHEMICAL REARRANGEMENTS OF QUINONE MONOKETALS. SYNTHESIS OF SUBSTITUTED CYCLOPENTENONES
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The irradiation of quinone ethylene monoketals in acetic acid leads in high yield to substituted 4-(alkoxycarbonyl)cyclopentenones.
- Pirrung, Michael C.,Nunn, David S.
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- Ultrasensitive electrochemical detection of methyl parathion pesticide based on cationic water-soluble pillar[5]arene and reduced graphene nanocomposite
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We report a rapid, sensitive and selective electrochemical sensor based on pillar[5]arene (CP5) reduced graphene (rGO) nanohybrid-modified glassy carbon electrode CP5-rGO/GCE for the trace detection of methyl parathion (MP) by differential pulse voltammetry (DPV) for the first time. Compared to beta-cyclodextrin (β-CD)-functionalized reduced graphene (rGO)-modified GCE β-CD-rGO/GCE, the proposed CP5-rGO/GCE sensor exhibits excellent electrochemical catalytic activity, rapid response, high sensitivity, good reproducibility and anti-interference ability towards MP. The recognition mechanism of β-CD/MP and CP5/MP was studied by 1H NMR. The results indicate a higher supramolecular recognition capability between CP5 and MP compared to that between β-CD and MP. The β-CD-rGO and CP5-rGO nano-composites were prepared via a wet chemistry approach. The resulting nano-composites have been characterized by thermogravimetric analysis (TGA), fourier transform infrared spectrometry (FTIR), charge transfer resistance (Rct) and zeta potential. The CP5-rGO/GCE combines the merits of CP5 and rGO, and is used for quantitative detection of MP. It has a low detection limit of 0.0003 μM (S/N = 3) and a linear response range of 0.001-150 μM for MP. This method has been used to detect MP in soil and waste water samples with satisfactory results. This study provides a promising electrochemical sensing platform and is a promising tool for the rapid, facile and sensitive analysis of MP.
- Tan, Xiaoping,Liu, Yan,Zhang, Tingying,Luo, Shasha,Liu, Xi,Tian, Hexiang,Yang, Yang,Chen, Chunlian
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- A new class of flavonoids bearing macrocyclic polyethers by stereoselective photochemical cycloaddition reaction
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A new class of flavonoids bearing cyclic polyethers involving a phenyl ring was conveniently provided by the intramolecular photochemical dimerization of 2-chromonecarboxylic esters. Irradiation of 2-chromonecarboxylate with a polyether tethered at both ends promoted intramolecular [2 + 2] cyclobutane formation leading to 14- to 27-membered cyclic polyethers. The efficiency depended on the substituted position of the phenyl ring, with ortho- and meta-substituted derivatives giving cycloadducts in good chemical yields and quantum efficiencies, whereas the para-derivatives were inert toward photolysis. X-ray crystallographic analysis revealed that the stereochemistry of the macrocyclic cycloadducts exhibited C2-symmetry.
- Ishikawa, Hiroki,Uemura, Naohiro,Taira, Ryo,Sano, Kento,Yoshida, Yasushi,Mino, Takashi,Kasashima, Yoshio,Sakamoto, Masami
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p. 3911 - 3916
(2019/06/18)
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- Method for synthesizing hydroquinone dihydroxyl diethyl ether
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The invention relates to a method for synthesizing hydroquinone dihydroxyl diethyl ether and belongs to the technical field of synthesis of organic compounds. The method comprises the steps: carrying out synthesis by taking hydroquinone and epoxyethane as raw materials, adding hydroquinone, a ferrocene catalyst and an ether solvent into a reactor, carrying out vacuumizing, heating the reactor until hydroquinone is completely dissolved in the ether solvent under nitrogen protection, then, adding a chain extender into the reactor, heating the reactor to a polymerization reaction temperature, and carrying out hydroquinone dihydroxyl diethyl ether synthesis under polymerization reaction pressure; and after the reaction ends, carrying out cooling, and subjecting crystallizing mother liquor to normal-pressure or reduced-pressure rectification, so as to separate out the ether solvent. The hydroquinone dihydroxyl diethyl ether is synthesized by the method, the problems in the conventional technologies that the preparation process is complicated and the quality of product is poor are solved, and the obtained product is reasonable in distribution, light in color and luster and low in byproduct content.
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Paragraph 0023; 0057; 0058; 0059
(2016/11/17)
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- One-pot synthesis of cyclophane-type macrocycles using manganese(iii)- mediated oxidative radical cyclization
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Cyclophane-type macrocyclic compounds from 21 to 56 members having two fused dihydrofuran rings were synthesized by the manganese(iii)-mediated oxidation of terminal dienes with bis(3-oxobutanoate)s containing aromatics. The reaction detail, characterization and reaction pathways are described. The Royal Society of Chemistry 2011.
- Ito, Yosuke,Tomiyasu, Yuichi,Kawanabe, Takahiro,Uemura, Keisuke,Ushimizu, Yuu,Nishino, Hiroshi
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p. 1491 - 1507
(2011/04/23)
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- Highly ordered assembly of π-stacked distyrylbenzenes by oligoadenines
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A well-defined nanofibrous structure with lengths of several hundred nanometers and cross-sectional width of a single size (~6±0.5 nm) was self-assembled by oligoadenines, dA20, and thymine-appended distyrylbenzene through binary complementary A-T hydrogen bond formation and the strong π-π stacking interactions. This demonstrated a useful supramolecular self-assembling approach to control the packing order of π-conjugated molecules and provided a practical means to enhance the optical properties of a material.
- Yang, Wanggui,Xia, Ping Fang,Wong, Man Shing
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supporting information; experimental part
p. 4018 - 4021
(2010/11/05)
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- Synthesis of new cores and their use in the preparation of polyester dendrimers
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Six dendrimer and dendron cores terminated by hydroxyl groups that are neither phenolic nor cleavable by hydrogenolysis have been prepared in a consistent one-pot manner from terminal allyl groups by reduction of the product of reductive ozonolysis. Some of the terminal allyl derivatives are new and others have been prepared by new methods. The well-known O-benzylidene derivative of 2,2′-bis(hydroxymethyl)propanoic acid was shown to be the cis-stereoisomer. A new AB3-type anhydride, tris(benzyloxymethyl) acetic anhydride has been prepared. It was demonstrated that these cores and dendrons could be assembled into first and second generation homo- and mixed polyester dendrimers.
- Twibanire, Jean-D'Amour K.,Al-Mughaid, Hussein,Grindley, T. Bruce
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experimental part
p. 9602 - 9609
(2011/01/03)
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- One-pot alkoxylation of phenols with urea and 1,2-glycols
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A one-pot epoxide-free alkoxylation process has been developed for phenolic compounds. The process involves heating phenols and urea in 1,2-glycols at 170-190 °C using Na2CO3/ZnO as co-catalysts under atmospheric conditions. During the course of this new alkoxylation reaction, a five-membered ring cyclic carbonate intermediate, ethylene carbonate (EC) or propylene carbonate (PPC), was produced in-transit as the key intermediate and was subsequently consumed by phenols to form alkoxylated ether alcohols as final products in excellent yields. For instance, phenol, bisphenol A (BPA), hydroquinone and resorcinol were converted into their respective mono-alkoxylated ether alcohols on each of their phenolic groups in 80-95% isolated yields. In propoxylation of phenols, this approach shows great product selectivity favoring production of high secondary alcohols over primary alcohols in isomeric ratios of nearing 95/5. Since ammonia (NH3) and carbon dioxide (CO2) evolving from the reaction can be re-combined in theory into urea for re-use, the overall net-alkoxylation by this approach can be regarded as a simple condensation reaction of phenols with 1,2-glycols giving off water as its by-product. This one-pot process is simple, safe and environmentally friendlier than the conventional alkoxylated processes based on ethylene oxide (EO) or propylene oxide (PO). Moreover, this process is particularly well-suited for making short chain-length alkoxyether alcohols of phenols.
- Lin, Hsing-Yo,Dai, Shenghong A.
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experimental part
p. 167 - 173
(2011/04/19)
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- Preparation, characterization and luminescent properties of lanthanide complexes with a new aryl amide bridging ligand
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A new aryl amide type bridging ligand 1,4-bis{[(2′-benzylaminoformyl)phenoxyl]ethoxyl}benzene (L) and its complexes with lanthanide ions (Ln = Pr, Nd, Sm, Eu, Gd, Tb, Dy, Er) were synthesized and characterized by elemental analysis, infrared spectra and electronic spectra. At the same time, the luminescent properties of the Sm, Eu, Tb and Dy complexes in solid state and the Tb complex in solvents were also investigated. At room temperature, these four complexes exhibited characteristic luminescence emissions of the central metal ions under UV light excitation and could be significant in the field of supramolecular photonic devices.
- Li, Ya-Fei,Tang, Kuan-Zhen,Tang, Yu,Liu, Wei-Sheng,Tan, Min-Yu
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scheme or table
p. 1153 - 1157
(2009/02/06)
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- Alkoxylation process for preparing ether alkanol derivatives of phenolic compounds
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This invention provides an alkoxylation process for creating alkoxylating chain extension of phenolic compounds by reacting phenolic compounds with alkylene glycol and urea in the presence of suitable catalysts to obtain alkoxylated compounds, which may be used as polymer intermediates, especially for use as raw materials to synthesize polyurethane (PU) or polyester.
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Page/Page column 4
(2008/12/07)
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- Aromatic ethers and process for producing aromatic ethers
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According to a production process, aromatic ethers are producible by reacting phenols with an oxirane compound with use of an anion exchange resin as a catalyst. According to another production process, aromatic ethers having an alcoholic hydroxyl group are producible by a crystallization-purification step of using a solvent having a solubility parameter ranging from 7.5 to 12.5 for purification by crystallization. Further, according to still another production process, producible are aromatic ethers having an alcoholic hydroxyl group, wherein the content of a metal in the aromatic ethers is less than 100 ppm by mass, and the content of a halogen element in the aromatic ethers is less than 100 ppm by mass.
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- Synthesis of alkyl-substituted, strapped porphyrin to prepare stable alkyl-chain-assisted self-assembled monolayers of porphyrin conjugates
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An alkyl-substituted, strapped porphyrin was synthesized aiming at the preparation of stable alkyl-chain-assisted self-assembled monolayers (SAMs) of porphyrin conjugates. We confirmed that the synthesized strapped porphyrin could form stable SAMs by scanning tunneling microscopy (STM). This approach will lead to the functionalization of alkyl-chain-assisted SAMs by introducing a variety of functional groups in the strapped moiety.
- Ikeda, Taichi,Asakawa, Masumi,Miyake, Koji,Shimizu, Toshimi
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p. 1418 - 1419
(2007/10/03)
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- Synthesis of a new class of difunctional tetraphenylene crown ethers
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Three new substituted tetraphenylene crown ethers have been made. Bis(5- carbomethoxy-1,3-phenylene)-bis(p-phenylene)-(3x + 6)-crown-x, where x = 12, 16, and 20 (11b-11d) were synthesized via [1 + 1] cyclization of methyl 3,5- bis[ω-chloro(oligoethyleneoxy)]benzoates (13b-3d) with methyl 3,5-bis[ω- (p-hydroxyphenoxy)(oligoethyleneoxy)]benzoates (16b-6d) using K2CO3 as base and tetrabutylammonium iodide as a phase transfer agent in dimethylformamide (DMF). The corresponding 30-membered (x = 8) macrocycle 11a could not be made by this approach; only the elimination product, 3,5-bis(vinyloxy)benzoic acid (19), was isolated. 16a-16d were made via alkylation of p-benzyloxyphenol (14) with 13a-13d, respectively, followed by hydrogenolysis with Pd/C as catalyst. No complexation of these macrocycles with dibenzylammonium ions was detected by NMR spectroscopy, but weak complexation of 11d with a paraquat derivative was observed.
- Gibson, Harry W.,Nagvekar, Devdatt S.,Delaviz, Yadollah,Bryant, William S.
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p. 1429 - 1436
(2007/10/03)
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- Photochemical rearrangements of quinone monoketals
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We have studied the photochemistry of over 15 quinone cyclic monoketals, which were prepared by diol exchange from the dimethyl ketals, Swanton oxidation/hydrolysis, or direct ketalization. Their reactions in acidic media are generally explained by the classical mechanism for cyclohexadienone photochemical (di-π-methane) rearrangements: photocyclization to a cyclopropane-oxyallylcation that is protonated, followed by sovolysis. This reaction pathway provides, after hydrolysis, β-carboxy-substituted cyclopentenones. With a substituent at the β-position of the quinone monoketal, rearrangement selectivity is modestly in favor of the more substituted alkene product. With a substituent at the α-position of the quinone monoketal, rearrangement selectivity is strongly in favor of the less substituted alkene product. Possible mechanistic reasoning to explain these observations is offered.
- Pirrung, Michael C.,Nunn, David S.
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p. 5707 - 5738
(2007/10/03)
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