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171.
Gerhard Buchbauer Angela Fischlmayr Ernst Haslinger Wolfgang Robien Horst Völlenkle Carla Wassmann 《Monatshefte für Chemie / Chemical Monthly》1984,115(6-7):739-748
2-Hydroxy-13-oxo-tricyclo[7.3.1.02,7]tridecane derivatives can be obtained by reaction of cyclohexanone with alcohols under alkaline conditions. The unambiguous assignment of all signals of the1H-NMR- and13C-NMR-spectrum is possible by 2D-1H-13C-shift correlation and 2D-INADEQUATE. Compound1 crystallizes in space group P21/n witha=8.518 (1),b=14.789 (2),c=19.321 (2) Å, =94.91 (1)°,Z=8,D
c
=1.22 Mg cm–3. The structure refined toR=0.100 andR
w
=0.097 for 1719 observed reflections. Two independent molecules form centrosymmetric hydrogen-bonded dimers.Part V:Haslinger E.,Kalchhau-ser H.,Robien W.,Steindl H., Monatsh. Chem.115, 597 (1984). 相似文献
172.
The reaction of dimethylzinc and tri(tert‐butyl)silylphosphane in toluene yielded dimeric methylzinc tri(tert‐butyl)silylphosphanide ( 1 ) which crystallized tetrameric. Compound 1 was deprotonated with sodium in DME and the solvent‐separated dimeric ion pair [(dme)3Na]+ [(dme)Na(MeZn)2(μ‐PSitBu3)2]? ( 2 ) was isolated. The reaction of 1 in THF with two equivalents of potassium and one equivalent of tri(tert‐butyl)silylphosphane gave dimeric [{tBu3Si(H)P}{(thf)2K}2(MeZn)(PSitBu3)]2 ( 3 ). Both of these phosphanylzincates contain Zn2P2 cycles with Zn‐P bond lengths of approximately 237 pm, whereas in 1 larger Zn‐P bond lengths of 248.5 pm were found due to the larger coordination numbers of the phosphorus and zinc atoms. 相似文献
173.
Monserrat García Gerhard van Vliet Mattijs G. J. ten Cate Francisco Chvez Ben Norder Bart Kooi Werner E. van Zyl Henk Verweij Dave H. A. Blank 《先进技术聚合物》2004,15(4):164-172
Solution impregnations, pulltrusion and film stacking are widely used methods to prepare thermoplastic composite materials. Extruders are used to melt the polymer and to incorporate fibers into the polymer in order to modify physical properties. In this article, the compounding of colloidal silica nanoparticles filled polyamide‐6 (PA‐6) is achieved using a twin‐screw extruder, which has a significant market share due to its low cost and easy maintenance. The experiments were performed at 250 rpm and the bulk throughput was 6 kg h?1 with a pump pressure of 30 bars. The composites were characterized with nuclear magnetic resonance (NMR), wide angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC) and transmission electron microscopy (TEM). As determined by WAXD, the PA‐6 showed higher amounts of γ‐phase when compared to other synthesis methods such as in situ polymerization. TEM pictures showed that the silica particles aggregated nevertheless, upon addition of 14% (w/w) silica the E‐modulus increased from 2.7 to 3.9 GPa indicating that an effective mechanical coupling with the polymer was achieved. The behavior, illustrated with dynamic mechanical analysis (DMA) curves, indicated that in general when a filled system is compared to unfilled material, the values of the moduli (E′ and E″) increased and tan δ decreased. Determination of molecular mass distribution of the samples by means of size exclusion chromatography (SEC) coupled to a refractive index (RI), viscosity (DV) and light scattering (LS) detector revealed that the addition of silica did not decrease the average molecular weight of the polymer matrix, which is of importance for composite applications. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
174.
Cornelissen C Erker G Kehr G Fröhlich R 《Dalton transactions (Cambridge, England : 2003)》2004,(23):4059-4063
Treatment of the complexes [(C(5)H(4)PR(2))(2)Zr(CH(3))(2)](b: R = isopropyl; c: R = cyclohexyl) with the reagent HIr(CO)(PPh(3))(3) (2b) yield the heterobimetallic complexes [mu-C(5)H(4)PR(2))(2)(H(3)C-Zr-Ir(CO)(PPh(3)))] (4b, 4c) with evolution of methane. The reaction of the -PPh(2) substituted analogue with initially yields an intermediate [(H(3)C)(2)Zr(mu-C(5)H(4)PPh(2))(2)Ir(H)(CO)(PPh(3))] 5a, that still contains both methyl groups at zirconium and does not contain a metal-metal bond. At room temperature, the intermediate reacts further with methane formation to eventually yield the (Zr-Ir) complex 4a. The corresponding [mu-C(5)H(4)PR(2))(2)(H(3)C-Zr-Rh(CO)(PPh(3)))] complexes 3a (R = Ph) and 3b (R = isopropyl) react cleanly with isopropyl alcohol to liberate methane and yield the corresponding [mu-C(5)H(4)PR(2))(2)(Me(2)CHO-Zr-Rh(CO)(PPh(3)))] products (7a, 7b). Carefully monitoring the reaction of with Me(2)CHOH by NMR revealed that the Zr-Rh functionality is attacked first to give the intermediate [Me(Me(2)CHO)Zr([micro sign]-C(5)H(4)PR(2))(2)Rh(H)(CO)(PPh(3))] (6b). This intermediate then reacts further to cleave off methane and re-form the (Zr-Rh) metal-metal bond to yield the product 7b. The tetrametallic mu-oxo-(Zr-Rh) metallocene derivate 11a was obtained starting from the (Zr-Rh) complex 3a and it was characterized by X-ray diffraction. It may be that this reaction is also initiated by H-OH addition to the [Zr-Rh] metal-metal bond. 相似文献
175.
Accurate lower and upper bounds for the nonrelativistic lowest energies1
E
0 and3
E
0 of the singlet and triplet-system of the4He-Isotop are calculated with the linearized method of variance minimization. The same was done for1
E
1 the energy of the first excitedS-state 21
S.
The results especially for1
E
0 and3
E
0 in a.u. are −2.90330769975 ≤1
E
0 ≤ −2.90330769218 −2.17493242637 ≤3
E
0 ≤ −2.17493242459 i.e. the values are determined with an absolute error smaller than 0.00167 cm−1 for1
E
0 and 0.00039 cm−1 for3
E
0. 相似文献
176.
177.
178.
We use Bayesian inference to derive the rate coefficients of a coarse master equation from molecular dynamics simulations. Results from multiple short simulation trajectories are used to estimate propagators. A likelihood function constructed as a product of the propagators provides a posterior distribution of the free coefficients in the rate matrix determining the Markovian master equation. Extensions to non-Markovian dynamics are discussed, using the trajectory "paths" as observations. The Markovian approach is illustrated for the filling and emptying transitions of short carbon nanotubes dissolved in water. We show that accurate thermodynamic and kinetic properties, such as free energy surfaces and kinetic rate coefficients, can be computed from coarse master equations obtained through Bayesian inference. 相似文献
179.
Zusammenfassung Flüssige und feste Legierungen im System Au–Cd wurden von 60 bis 90 At% Cd zwischen 653° und 873°K mit derEMK-Methode untersucht und thermodynamische Eigenschaften berechnet. Die Aktivitäten von Cd zeigen stark negative Abweichungen vom idealen Verhalten. Die partiellen molaren Enthalpien sind negativ und verschieben sich mit zunehmender Temperatur zu weniger negativen Werten, die partiellen molaren Entropien sind positiv und nehmen mit zunehmender Temperatur zu. Aus eigenen Werten und Literaturdaten wurden integrale thermodynamische Größen für die Schmelzen im gesamten System Au–Cd bei 1000°K berechnet. Für einige feste Cd-reiche Phasen wurden ebenfalls Aktivitäten erhalten und aus den Knickpunkten derEMK-Temperatur-Kurve Temperaturen von Phasenübergängen bestimmt.
Mit 5 Abbildungen
Herrn Prof. Dr.H. Nowotny gewidmet. 相似文献
Thermodynamic investigations in theAu–Cd-system
Liquid and solid alloys in the Au–Cd system were investigated between 60 and 90 at % Cd and 653°–873°K by theemf method, and thermodynamic properties were calculated. The activities of Cd exhibit strong negative deviations from ideal behavior. Partial molar enthalpies are negative and become less so with increasing temperature; partial molar entropies are positive and increase with increasing temperature. A consistent set of integral thermodynamic data for liquid solutions of the entire Au–Cd system at 1000°K were calculated using values taken from the literature. Activities for some solid Cd-rich phases were also obtained. From discontinuities in theemf vs. temperature curve temperatures of phase transitions were determined.
Mit 5 Abbildungen
Herrn Prof. Dr.H. Nowotny gewidmet. 相似文献
180.