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91.
Leila S. Boulos Ewies F. Ewies Amin F. M. Fahmy Maysa E. Mohram 《Phosphorus, sulfur, and silicon and the related elements》2013,188(6):790-803
Abstract The reaction of 5(4H)-pyrazolone with phosphorus ylides afforded new triphenylphosphanylidene alkanone derivatives. Moreover, its benzylidene derivative reacted with Wittig–Horner reagents to give the corresponding dialkoxyphosphoryl, alkyl phosphonate, and heterocyclic products. Treatment of pyrazole-4-carbaldehyde with Wittig–Horner reagents and trialkyl phosphites gave the respective alkyl phosphonate adducts. Mechanisms accounting for the formation of the new products are discussed. The biological activity of some of the newly synthesized compounds was also examined. 相似文献
92.
93.
Ali Reza Mahdavian Mahdi Abdollahi Leila Mokhtabad Farshid Ziaee 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(10):1583-1596
Many reports exist in the literature about the application of 1H and 13C‐NMR techniques to analyze the copolymer structure and composition and also determination of reactivity ratios. In this work, on‐line 1H‐NMR spectroscopy has been applied to identify reactivity ratios of itaconic acid and acrylonitrile in the solution phase (DMSO as the solvent) and in the presence of AIBN as the radical initiator. All the peaks corresponding to the existing protons were assigned quietly. Therefore, the kinetics of the copolymerization reaction was investigated by studying the variation of integral of two characteristic peaks regarding each monomer. The obtained data were used to find the reactivity ratios of acrylonitrile and itaconic acid by linear least‐squares methods such as Finemann‐Ross, inverted Finemann‐Ross, Mayo‐Lewis, Kelen‐Tudos, extended Kelen‐Tudos and Mao‐Huglin. In addition, a non‐linear least‐square method (Tidwell‐ Mortimer) was used at low conversions. Extended Kelen‐ Tudos and Mao‐Huglin were applied to determine reactivity ratio values at high conversions as well. 相似文献
94.
James M. Wescott Tae Ho Yoon David Rodrigues Laura A. Kiefer Garth L. Wilkes James E. McGrath 《高分子科学杂志,A辑:纯化学与应用化学》2013,50(8):1071-1085
Abstract Poly(aryl imide)-poly(dimethyl siloxane) randomly segmented copolymers were synthesized by essentially a one-step solution imidization process in a solvent system consisting of predominately o-dichlorobenzene with a small amount of n-methylpyrolidone. This solvent combination was selected because of its ability to afford homogeneous solutions throughout the polymerization process. This enabled copolymers of any desired poly(dimethyl siloxane) composition to be prepared. A hydrolytically stable triphenylphosphine oxide containing diamine, bis(3-amino-phenoxy-4′-phenyl)phenylphosphine oxide, was utilized as a chain extender and together with oxydiphthalic anhydride formed the hard segment in these copolymers. The soft segment was formed from α,ω-aminopropyl poly(dimethyl siloxane) oligomers of controlled molecular weight. The presence of phosphorus and silicon contributes several unique properties to the system, including enhanced solubility, thermal stability, and flame resistance. High molecular weight copolymers containing up to 60% (w/w) of the poly(dimethyl siloxane) segments were successfully prepared using this method. Gel permeation chromatography analysis, based on a universal calibration curve in CHCl3, was performed to determine the molecular weights and distribution. These copolymers with 40-60% (w/w) poly(dimethyl siloxane) exhibited upper Tg values ranging from 130 to 180°C and showed substantial char yields at 750°C in air, which increased with siloxane content. Dynamic mechanical analysis confirmed the anticipated microphase behavior by the presence of two separate glass-transition regions. Both small angle x-ray scattering and transmission electron microscopy measurements determined on well-characterized transparent cast films were used to better demonstrate the multiphase nature of these copolymers. 相似文献
95.
Bruno R.S. de Paula Dávila S. Zampieri J. Augusto R. Rodrigues Paulo J.S. Moran 《Tetrahedron: Asymmetry》2013,24(17):973-981
Enones (Z)-3-methyl-(Z)-3-chloromethyl- and (Z)-3-bromomethyl-4-R-3-buten-2-one (R = n-pentyl, phenyl, 2′- and 4′-chlorophenyl, 3′- and 4′-nitrophenyl, 4′-methoxyphenyl) were synthesized and subjected to reduction by the microorganisms Saccharomyces cerevisiae andGeotrichum candidum. Whereas the bioreduction of 3-methy-4-R-3-buten-2-ones afforded the corresponding (S)-4-R-3-methybutan-2-ones, the bioreduction of 3-chloromethyl- and 3-bromomethyl-4-R-3-buten-2-ones afforded the corresponding (R)-4-R-3-methybutan-2-ones. 相似文献
96.
97.
Peter W. Kenny Carlos A. Montanari Igor M. Prokopczyk Fernanda A. Sala Geraldo Rodrigues Sartori 《Journal of computer-aided molecular design》2013,27(8):655-664
The ability to modify chemical structures in an automated and controlled manner is useful in molecular design. This Perspective introduces the MUDO molecule editor and shows how automated molecule editing can be used to standardize structures, enumerate tautomeric and ionization states, identify matched molecular pairs. Unlike its predecessor Leatherface, MUDO can also process 3D structures and this capability can be used to link non-covalently docked ligands to proteins. 相似文献
98.
Alexandre Carlos Camacho Rodrigues José Luiz Fontes Monteiro 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1297-1302
The effect of the calcination procedure on the decomposition of the [Pt(NH3)4]2+ complex in a cesium-containing NaX zeolite was studied by thermal decomposition accompanied by mass spectrometry and diffuse reflectance spectroscopy, as well as electron paramagnetic resonance and infrared spectroscopy. The decomposition of the complex took place in two steps. Under oxygen, the [Pt(NH3)4]2+ complex was first converted into the [Pt(NH3)2]2+ complex in the first step, with predominant nitrogen release. In the second step, corresponding to the decomposition of the remaining two amine ligands, NO was also formed and adsorbed. Oxygen paramagnetic species were also observed. Under He, the decomposition also occurred in two steps with H2 release. 相似文献
99.
José Roberto dos Santos Politi Paulo Roberto Rodrigues de Matos Maria José Araújo Sales 《Journal of Thermal Analysis and Calorimetry》2013,111(2):1437-1442
Demand for lubricating oils is increasing in the growing Brazilian economy. The use of vegetable bases in exchange of minerals can bring socio-economic and environmental benefits for Brazil. The purpose of this study is to compare the thermal and oxidative stability of vegetable oils related to the bases commonly used as lubricants. In this study, thermogravimetric analysis of castor oil, cotton oil, macauba’s almond oil, passion oil, paraffinic mineral oil, naphthenic oil (NH-140) and synthetic oil (Etro) was performed in inert and oxidative atmosphere to study the thermal and oxidative degradation of the vegetable oils related to the most common lubricants’ oils base. These oils’ oxidation stability were determined by standard procedures (ISO 6886). The use of mineral oil’s additives in these vegetable oils was tested to verify the viability of these additives to improve the oxidative stability of the vegetable oils. The castor oil and the cotton oil presented results of thermal analysis similar to the mineral and synthetic bases values. The castor oil was the only vegetable oil that showed a great oxidative stability. All other vegetable oils had their oxidative stability significantly increased by the additives. 相似文献
100.
Leila Khoshmaram Hossein Abdolmohammad‐Zadeh Elham Ghaffarzadeh 《Journal of separation science》2019,42(3):736-743
In this work, a new, cheap, simple, fast, and low organic solvent consuming procedure is proposed for isolation, enrichment, and gas chromatographic determination of some phthalate esters in edible oils. The method is based on a combination of air‐assisted liquid–liquid extraction and dispersive liquid–liquid microextraction followed by a drying step under N2 gas. Several experimental parameters affecting both extraction and preconcentration steps were investigated and optimized. Under the optimum conditions for the proposed method, wide linear ranges (0.05–800 μg/L) and low detection limits (0.007–0.023 μg/L) were observed. The ranges of enrichment factors and extraction recoveries were 68–340 and 14–68%, respectively. Eventually, the target analytes were successfully determined in different edible oils using the proposed method. 相似文献