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991.
992.
Marta Sánchez-Cabezudo Margarita G. Prolongo Catalina Salom Rosa M. Masegosa 《Journal of Thermal Analysis and Calorimetry》2006,86(3):699-705
The cure kinetics
and morphology of diglycidyl ether of bisphenol A (DGEBA) modified with polyvinyl
acetate (PVAc) using diaminodiphenylmethane (DDM) as hardener were investigated
through differential scanning calorimetry (DSC) and environmental scanning
electron microscopy (ESEM). Isothermal curing measurements were carried out
at 150, 120 and 80°C. The kinetic parameters were obtained using the general
autocatalytic chemically controlled model. The comparison of the kinetic data
indicates that the presence of PVAc does not change the autocatalytic nature
of the cure reaction. Two T
g’s
were observed in the fully cured samples of the modified systems. ESEM micrographies
confirm the biphasic morphology. 相似文献
993.
Harald Stueger Markus Braunwarth Gottfried Fuerpass Judith Baumgartner Robert Saf 《Monatshefte für Chemie / Chemical Monthly》2006,137(5):595-603
Summary. The previously unknown ruthenio disilanes Rp–Si2Me4–C6H4X (Rp = η5-C5H5Ru(CO)2; X = H, Br, –CHO, CH=C(CN)2) were synthesized from ClSi2Me4C6H4X (X = H, Br) and Rp− using conventional chemical methods. Trends in the UV/Vis absorption spectra indicate strong electronic coupling within the
Rp–Si–Si–Caryl fragment and, therefore, closely resemble the ones observed for the corresponding iron complexes. The four compounds however,
were shown to be less sensitive towards UV irradiation. The crystal structure of Rp–Si2Me4–C6H4CH=C(CN)2 was determined by X-ray diffraction and exhibits an all-trans-array of the Ru–Si–Si–Caryl moiety, what is a basic requirement for optimal through-bond interaction. 相似文献
994.
Photoreduction of nitro compounds is accompanied by formation of various radical products that can react with the starting
nitro compound, thus causing deviation of the decomposition kinetics from the first-order kinetics with respect to the nitro
compound. The results of quantum chemical modeling of the reactions of nitro compounds with radicals and the pathways of further
transformations of radical adducts formed in the reactions are presented.
Published in Russian in Izvestiya Akademii Nauk. Seriya Khimicheskaya, No. 2, pp. 202–206, February, 2006. 相似文献
995.
Monir Uddin Antonis G. Hatzidimitriou Maria Lalia-Kantouri Chris Tsiamis 《Structural chemistry》1997,8(2):131-139
The infrared and electronic excitation spectra of a series of new nickel(II) chelates containing an-diimine (or nitrogenous base, enR) and the anion of a-dione (1,3-ketoenol or 1,3-ketoester,H) were obtained in the solid state and in solution. The composition and the overall structure of the new chelates in the solid state depends on ligand concentration, the substituents within the-dionato moiety and the counterion present. The IR and electronic excitation spectra of [Ni(enR)2
]NO3 and [Ni(enR)(O2NO)] indicate, in conjunction with other physicochemical measurements, bidentate coordination of the ligands, while the spectral shifts reveal replacement of the (O,O)nitrato group by basic solvents. The existence of the nickel(II) in an octahedral environment is confirmed by an X-ray structure analysis of [Ni(dpamH)2acac]NO3 · CH3OH (monoclinic, space groupP2l/n, a=17.296(1),b=7.462(1),c=21.604(3) å,=95.65(1),Z=4, R=0.0534,Rw=0.0600), where dpamH denotes the 2,2-dipyridylamine. 相似文献
996.
利用~(13)C-NMR方法研究了弱碱K_2CO_3存在下酚酞成盐反应及其与活性双卤砜亲核缩聚反应过程中的结构特征。对一系列碱性条件下酚酞(PP)与4,4'-二氯二苯砜(DCDPS)的缩聚反应的研究表明任何影响内酯结构酚酞盐生成的因素都会严重阻碍聚合反应的进行。对模型化合物存在下K_2CO_3在极性非质子溶剂中的溶解/解离行为的研究结果表明酚酞类Card。双酚与固体K_2CO_3之间可能存在着一种特殊的络合作用。基于我们系列研究结果,本文中总结提出了弱碱K_2CO_3存在下酚酞的反应机理。 相似文献
997.
998.
A series of different commercial membranes were characterized by their moisture absorption and desorption properties under controlled humidity and temperature conditions. This work was made possible by combining the features of a constant humidity conditioning chamber with those of a thermogravimetric (TG) apparatus. These two modules were interconnected by tubing, rotameters, an atmosphere-recycling microbellows pump and switching valves. Under programmed heating and isothermal conditions reproducible data were obtained in terms of weight-gain or weight-lossvs. time and pore size. Evaluation of the resulting TG curves allowed us to report reasonable differences in the materials, some of which had been previously surface-modified by the manufacturer. 相似文献
999.
A. T. Baryshnikov V. I. Erashko N. I. Zubanova B. I. Ugrak S. A. Shevelev A. A. Fainzilberg V. V. Semenov 《Russian Chemical Bulletin》1992,41(9):1657-1664
The condensation of dinitromethane with glyoxal has been investigated and it has been demonstrated that 1,1,4,4-tetranitro-2,3-butandiol, -hydroxy-,-dinitropropionic acid or their mixture may be formed. Interaction of 1,1,4,4-tetranitro-2,3-butandiol or 1,4-dibromo-1,1,4,4-tetranitro-2,3-butanediol diacetates with sodium azide leads to bis(5-nitro-1,2,3-triazol-4-yl) via intermediate 1,1,4,4-tetranitro-1,3-butadiene.For communication 3, see [1].N. D. Zelinskii Institute of Organic Chemistry, Russian Academy of Sciences, 117913 Moscow. Translated from Izvestiya Akademii Nauk, Seriya Khimicheskaya, No. 9, pp. 2123–2131, September, 1992. 相似文献
1000.
From methyl-5-acetylamino-7,8-anhydro-4,9-O-bis-(t-butyldimethylsilyl)-3,5-dideoxy--D-glycero-D-galacto-2-nonulopyranosidonic acid methylester (1) the derivatives1 a and1 b were obtained by removing the 9-O-(t-butyldimethylsilyl)group withBu
4NF, followed by acetylation. Treatment of1 b with 80% acetic acid and acetanhydride/pyridine yields the 8-epi-N-acetylneuraminic acid derivative2 a and the 7-epi-N-acetylneuraminic acid derivative3 a in a ratio of 3:1 (Scheme 1). The structure elucidation of2 b was achieved by converting2 b via the 4,9-bis-O-(tBDMSi)-8-O-tosyl-derivative2 d into the epoxide1 (Scheme 2). Using the same sequence the epoxides4 and5 were transformed into theN-acetylneuraminic acid derivative6 a and the 7,8-bis-epi-N-acetylneuraminic acid derivative7 a (Scheme 3). After treatment with sodium hydroxide and 0.025m HCl and Dowex 50 H+ the 8-epi-, 7-epi- and 7,8-bis-epi-N-acetylneuraminic acids2,3, and7 were obtained. These three compounds were tested withCMP-N-acetylneuraminic acid synthetase.
Herrn KollegenK. Schlögl mit den besten Wünschen zum 60. Geburtstag. 相似文献