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51.
52.
Bifunctional benzoxazines: Synthesis and polymerization of resorcinol based single isomers 下载免费PDF全文
Hannes Schäfer André Arnebold Johannes Stelten Jordi Marquet Rosa María Sebastián Andreas Hartwig Katharina Koschek 《Journal of polymer science. Part A, Polymer chemistry》2016,54(9):1243-1251
Aside from their outstanding properties such as thermal and chemical stability and excellent mechanical performance, benzoxazines suffer from high polymerization temperatures. Isomeric mixtures of bifunctional benzoxazines based on resorcinol proved already to be highly reactive monomers enabling polymerizations at lower temperatures. This contribution describes the polymerization behavior of single benzoxazine isomers and furthermore the influence of different substituents at the aniline moiety on the curing temperature. Single isomers of bifunctional benzoxazines are now accessible in a straightforward one‐pot synthesis starting from resorcinol and the appropriate N‐phenyl functionalized aniline component. The asymmetric benzoxazine monomers bearing no (R‐a: Tpeak = 179 °C) or electron‐donating substituents in meta position to N (R‐3,5dma: Tpeak = 183 °C) succeed in lowering the polymerization temperature. Additionally, the impact of several initiating systems was studied resulting in a decrease of the polymerization temperature for all studied resorcinol derived benzoxazine isomers (down to 144 °C). © 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2016 , 54, 1243–1251 相似文献
53.
Hiroaki Oie Atsushi Mori Atsushi Sudo Takeshi Endo 《Journal of polymer science. Part A, Polymer chemistry》2013,51(18):3867-3872
A polyaddition system consisted of a bifunctional N‐n‐propyl benzoxazine and 2‐methylresorcinol ( MR ) that proceeds at ambient temperature has been developed. In this system, the aromatic ring of MR acted as a bifunctional monomer, reacting with a two equivalent amount of benzoxazine moieties via their ring‐opening reaction. The polyaddition gave the corresponding linear polymer bearing phenolic moieties bridged by Mannich‐type linkage in the main chain. The linear polymer had a high glass transition temperature, which was comparable to that of the linear polybenzoxazine synthesized by the ring‐opening polymerization of a monofunctional N‐n‐propyl benzoxazine. The employment of a bifunctional N‐allyl benzoxazine in the polyaddition system resulted in the formation of the corresponding polymer with allyl pendants, which exhibited improved heat resistance due to its thermally induced crosslinking reaction. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013 , 51, 3867–3872 相似文献
54.
The preparation of substituted 2-amino-4H-chromenes by a Na2CO3-catalyzed reaction of malononitrile, benzaldehydes, and phloroglucinol or resorcinol in aqueous medium and at room temperature is reported. The merits of this procedure include limited use of organic solvents, easy workup technique, and high purity of products. The 2-amino-4H-chromenes were prepared in yields of 54–96%. 相似文献
55.
Debao Wang Caixia Song Zhengshui Hu 《Journal of Dispersion Science and Technology》2013,34(7):1010-1012
Mono-dispersed Mg(OH)2 nanoflakelets have been prepared with the assistant of 4-(p-nitrophenylazo)resorcinol. The samples were characterized using XRD, TEM, and ED. Electron diffraction analysis showed that single crystalline nanoflakelets were obtained in hydrothermal process, and porous Mg(OH)2 nanosheets were prepared at lower temperature. Nitrogen adsorption isotherms show that the surface area of Mg(OH)2 nanosheets is 129 m2/g. Possible growth mechanism of the nanoflakelets is discussed. 相似文献
56.
Norman Kharasch Ajit S. Arora 《Phosphorus, sulfur, and silicon and the related elements》2013,188(1-3):1-50
Abstract All living organisms require sulfur for various metabolic processes. Sulfur occurs in enzymes, in structural proteins of cells, and in a wide variety of naturally occurring compounds which often play key roles in metabolism. The chemistry and biochemistry of sulfur compounds has been reviewed.1–3. 相似文献
57.
Wen-Hua Ji Qian-Shan Gao Yun-Liang Lin Hong-Mei Gao Xiao Wang Yan-Ling Geng 《合成通讯》2014,44(4):540-546
An efficient formal synthesis of (±)-glabridin was accomplished in 10 steps from resorcinol using Raney Ni to reduce carbon–carbon double bonds in α,β-unsaturated carbonyl compound as the key step.
[Supplementary materials are available for this article. Go to the publisher's online edition of Synthetic Communications® for the following free supplemental resource(s): Full experimental and spectral details.] 相似文献
58.
Iwona Peech Daniel Sibera Piotr Staciwa Urszula Narkiewicz Robert Cormia 《Molecules (Basel, Switzerland)》2020,25(22)
In this work, low-pressure synthesis of carbon spheres from resorcinol and formaldehyde using an autoclave is presented. The influence of reaction time and process temperature as well as the effect of potassium oxalate, an activator, on the morphology and CO2 adsorption properties was studied. The properties of materials produced at pressureless (atmospheric) conditions were compared with those synthesized under higher pressures. The results of this work show that enhanced pressure treatment is not necessary to produce high-quality carbon spheres, and the morphology and porosity of the spheres produced without an activation step at pressureless conditions are not significantly different from those obtained at higher pressures. In addition, CO2 uptake was not affected by elevated pressure synthesis. It was also demonstrated that addition of the activator (potassium oxalate) had much more effect on key properties than the applied pressure treatment. The use of potassium oxalate as an activator caused non-uniform size distribution of spherical particles. Simultaneously higher values of surface area and total pore volumes were reached. A pressure treatment of the carbon materials in the autoclave significantly enhanced the CO2 uptake at 25 °C, but had no effect on it at 0 °C. 相似文献
59.
S. I. Filimonov S. A. Filimonova A. S. Shashkov S. I. Firgang G. A. Stashina 《Russian Chemical Bulletin》2005,54(6):1500-1504
Condensation of 8-arylidenehexahydroquinazoline-2-thiones with di- and trihydroxybenzenes affords the new heterocyclic system,
viz., octahydrochromeno[3,2-i]quinazoline-2(1H)-thiones, in which the substituents in both the chromane and quinazoline rings can be varied over a wide range.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1456–1460, June, 2005. 相似文献
60.
敌百虫在碱性溶液中与间苯二酚反应可生成荧光性的化合物。敌百虫的浓度在每25mL0-150μg的范围内与荧光强度呈线性关系,回收率为91%-102%,相对标准偏差为4.6%,检测限为0.070mg/m^3。研究了23种离子和农药的干扰情况。 相似文献