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1.
M. Veber K.N.V. Duong F. Gaudemer A. Gaudemer 《Journal of organometallic chemistry》1979,177(1):231-237
Allylcobaloximes react under very mild conditions with ethyl bromomalonate to yield allyl-substituted ethylmalonates in good yield. In the case of crotyl-, 3,3 dimethyl, allyl- and cinnamyl-cobaloximes, the substitution occurs with total rearrangement of the allyl groups. Similar rearrangements are observed during the reactions of propargyl- and allenylcobaloximes with BrCH(CO2Et)2 yielding allenyl- and propargyl-malonic esters respectively. 相似文献
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The 1H NMR spectra of several six-coordinate cobalt(III) porphyrins of general formula L2Co(DPDME)CI, where DPDME=deuteroporphyrin dimethyl ester and L is an optically active ligand, have been measured at 250 or 400 MHz. In a few cases, two signals of equal intensity are observed for the L ligand protons. This magnetic non-equivalence, which never exceeds 0.04 ppm, is thought to arise from the planar chirality of the porphyrin ring, which makes a proton in the ligand L above the porphyrin ring and the corresponding proton below this ring diastereotopic. 相似文献
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Alain Gaudemer Franois Nief Rene Pontikis Jean Zylber 《Magnetic resonance in chemistry : MRC》1977,10(1):135-145
Conformational analysis using 1H n.m.r. data (δ, 3J and NOE) has been carried out on several derivatives of 2′,3′,-O-isopropylideneadenosine bearing various substituents at positions C-5′, C-8 and N-6. Conformational modifications are assigned to specific interactions between the sugar and purine moieties and also to solvent effects. 相似文献
6.
A. Gaudemer K. Nguyen-van-duong N. Shahkarami S.S. Achi M. Frostin-rio D. Pujol 《Tetrahedron》1985,41(19):4095-4106
Two examples of radical reactions involving cobalt complexes are described. The first one concerns the reactions of allylcobaloximes with 2-bromo 2-phenylacetonitriles leading to the corresponding monoallyl derivatives. It is shown that both the rate and regioselectivity of the reactions are affected by the nature of the substituents on the phenyl group: electron-withdrawing groups give higher rates and highly regiospecific reactions. The second type of radical reaction which finds useful synthetic applications is the oxidation of phenols by 02 catalyzed by Schiff base cobalt complexes. By choosing carefully the catalyst and the solvent, these oxidations can be highly selective, quinones being the major oxidation products in most cases. 相似文献
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The flow structure in the confined space between the outer ring, the cage and the balls of a bearing is investigated using a large scale model allowing to perform visualizations, by tracer and dot-paint techniques, and velocity measurements, by Laser Doppler Velocity (LDV), through the transparent rotating outer ring. The visualization results show, in the region between two consecutive balls, the existence of a reversed flow on the cage surface resulting from the aspiration and blowing effect of the rotation of the balls in their cage housings. Systematic measurements of azimuthal velocities in different cross-sections of the gap confirmed the qualitative visualziation findings in laminar flow. For turbulent flow the results show that the extension of the reversed flow region is reduced and the reversed velocities are proportionally smaller as compared to the laminar case.List of symbols
R
radial position
-
R
b
radius of the balls
-
R
c
radius evaluated at the external surface of the cage
-
R
e
radius evaluated at the inner wall of the outer cylinder
-
R
i
radius evaluated at the outer wall of the inner cylinder
-
R
m
radius of the center of the balls
-
Re
0
Reynolds number in the space between the fixed inner cylinder and the rotating outer cylinder: Re
0 = e
R
e(R
e - R
i)/v
-
Re
1
Reynolds number in the space between the inner and outer cylinders: Re
1 = 2e
R
e(R
e - R
i)/v
-
Re
Reynolds number in the outer cylinder/cage gap: Re = e
R
e(R
e - R
c)/v
-
U
axial velocity
-
V
azimuthal velocity
-
V
e
azimuthal velocity of the internal wall of the outer cylinder
-
V
i
azimuthal velocity of the external wall of the inner cylinder
-
Z
axial position
-
azimuthal position
-
kinematic viscosity
-
i
angular velocity of the inner cylinder
-
e
angular velocity of the outer cylinder
-
c
angular velocity of the balls about the axis of the bearing
-
r
angular velocity of the balls about their center
This work was performed as part of a research effort aimed at investigating the many aspect of ball bearings flooded in cryogenic liquids and supported financially by the Centre National d'Etudes Spatiales (CNES) la Société Européenne de Propulsion (SEP) and the Centre National de la Recherche Scientifique (CNRS). The authors wish to deeply thank the many individuals, and in particular Dr. G. Jeanblanc from CNES and Mrs. Pierre and Moëllo from SEP, for their continuous encouragement. 相似文献
9.
Complexes of cobalt(II) with Schiff-bases obtained by condensation of 5-formyl pyrimidine bases with di- or tri-amines have been synthesized and characterized by visible spectroscopy and magnetic susceptibilities. Their catalytic efficiency in the oxidation of 2,6-ditertbutylphenol by molecular oxygen was studied. The molecular structure of a cobalt(III) complex was reported. 相似文献
10.
A. Milhourat-Hammadi H. Chayrigues R. Levoy C. Merienne A. Gaudemer 《Journal of polymer science. Part A, Polymer chemistry》1991,29(9):1347-1357
Variations in PMR-15 composite properties could be due to by-products formed during the polymerization cycle. In order to identify these compounds, various condensation products derived from the three monomeric constituents of the resin: NE, BTDE, and MDA, have been synthesized and fully characterized by spectroscopic methods, mainly by 1H- and 13C-NMR. In these products, one or two MDA amino groups are replaced by amido or imido groups, leading to mono- and di-substituted MDA derivatives. Monosubstituted derivatives were obtained by first protecting one MDA amino group with a terbutoxycarbonyl group (Boc). The MDA's CH2 bridge of these molecules gives rise, in their 1H NMR spectra, to a characteristic resonance singlet, the position of which can be correlated to the nature of the amino substituents through 1H chemical shift increments. The latter provide a useful tool to predict the CH2, shifts in other compounds. Similar substituent increments are proposed for the chemical shifts of the MDA aromatic protons and carbon atoms. 相似文献