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61.
The microwave spectrum has been investigated for the molecule of Benzenesulphonyl chloride within the 8–18 Ghz frequency region. Several a and b type bands corresponding to the Cl35 and Cl37 Isotopes were observed and assigned. We have also used the CNDO/2 method in order to estimate some molecular parameters and the dipole moment. The theoretical calculation and the experimental data have been joined to derive a reliable structure of the molecule concluding that the Cl is located on the plane of the benzene ring. 相似文献
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Vitor Matos Julio D. Silva Dan Marchesin 《Bulletin of the Brazilian Mathematical Society》2016,47(2):545-559
Themain goal of ourwork is to showthat there exists a class of 2×2 Riemann problems for which the solution comprises a singlewave group for an open set of initial conditions. This wave group comprises a 1-rarefaction joined to a 2-rarefaction, not by an intermediate state, but by a doubly characteristic shock, 1-left and 2-right characteristic. In order to ensure that perturbations of initial conditions do not destroy the adjacency of the waves, local transversality between a composite curve foliation and a rarefaction curve foliation is necessary. 相似文献
64.
Unexpected reactivity of pyridinium salts toward alkynyl Fischer complexes to produce oxo‐heterocycles 下载免费PDF全文
María Inés Flores‐Conde Fabiola N. de la Cruz Julio López J. Óscar C. Jiménez‐Halla Eduardo Peña‐Cabrera Marcos Flores‐Álamo Francisco Delgado Miguel A. Vázquez 《应用有机金属化学》2018,32(3)
The unprecedented reaction of ketone‐containing aromatic pyridinium salts 3a ‐ e and alkynyl Fischer complexes 1a ‐ f proceeds via a mild domino process to provide 4,6‐disubstituted pyran‐2‐ones 5a ‐ k and 2,3,5‐trisubstituted furans 6a ‐ h (45‐97%). According of the results of isotopic labeling experiments, a mechanism involving an initial Michael addition appears to be the key step, obtaining a mesomeric structure responsible for the formation of both products. 相似文献
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In this work, the effect of addition of kaolinite and rice husk microparticles on the water vapor permeability of polylactic acid (PLA) was evaluated. The PLA-composites materials were characterized by X-ray diffraction, differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and optical microscopy. For the composite preparation, an experimental design was established using two factors: additive type and concentration. When evaluating the water vapor permeability of the composites, it was found that the incorporation of kaolinite at 1% and 5% reduced the permeability coefficient of PLA. Furthermore, the inclusion of 5% kaolinite showed an increase on the tensile strength of the material. By contrast, the addition of rice husk produced an increase on water vapor permeability of the material and a decrease of both the tensile strength and ductility (percent of elongation at fracture). The higher dispersion and more regular morphology of the kaolinite particles could explain the enhancement of the gas barrier. A similar thermal behavior was observed for both PLA and composite materials, confirming that no damage of these properties was caused with the incorporation of the filler particles. 相似文献
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Butylated hydroxytoluene enediyne: access to diradical and electrophilic quinone methide intermediates 下载免费PDF全文
Edyta M. Greer Cesar S. Quezada Christopher V. Cosgriff 《Journal of Physical Organic Chemistry》2015,28(5):365-369
A theoretical study was carried out on the unimolecular reaction of an enediyne with a fused butylated hydroxytoluene to internally scavenge the p‐benzyne diradical sites formed after the Bergman cyclization. The calculations revealed that the conversion of the p‐benzyne diradical (2‐tert‐butyl‐4‐methyl‐5,8‐didehydro‐1‐naphthalenol) to p‐quinone methide is favored over the conversion to a phenoxy/benzene diradical 4 in an approximate 95:5 ratio. Based on this model, the Bergman cyclization leads in a bifunctional manner to intermediates for competing reactivity with intermolecular H‐atom abstraction. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献