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61.
Joachim G. Liehr Richard M. Caprioli John H. Beynon Roger P. Morgan Wilhelm J. Richter 《Journal of mass spectrometry : JMS》1980,15(3):157-160
The oxygen rearrangement in molecular ions of 3-phenylpropionates has been investigated with the aid of mass analyzed ion kinetic energy spectra. Elimination of an allyl radical followed by expulsion of ketene from the molecular ion of allyl 3-phenylpropionate is shown to result in formation of protonated benzaldehyde. The oxygen rearrangement has been found to be inoperative in ionized methyl 3-methyl-3-phenylbutyrate. [M ? CH3 ? CH2CO]+ ions in the spectrum of the latter compound are formed by elimination of the 3-methyl substituent and subsequent methoxy migration. 相似文献
62.
A novel approach to the preparation of perfluorotail-functionalized triarylphosphines using a p-silyl substituent as the branching point has been developed. This approach enabled the attachment of between three and nine perfluorotails per phosphorus atom, resulting in the production of highly fluorous tris[p-(1H,1H,2H, 2H-perfluoroalkylsilyl)aryl]phosphines, P[C(6)H(4)-p-SiMe(3)(-)(n)()(CH(2)CH(2)C(x)()F(2)(x)()(+1))(n)()](3) (n = 1, 2, 3; x = 6, 8), containing between 50 and 67 wt % fluorine. (31)P NMR studies indicate that the phosphorus atoms, and consequently the sigma-donor and pi-acceptor properties of these phosphines, are not influenced by the electron-withdrawing perfluoroalkyltails. The fluorous triarylphosphines are readily soluble in fluorous solvents and display fluorous phase preference in several fluorous biphasic systems. The phase partitioning of these fluorous ligands, as well as their donor properties, is discussed in relation to their potential for fluorous biphasic catalyst separation. 相似文献
63.
K. Nomura H. Reuther E. Richter Y. Ujihira 《Journal of Radioanalytical and Nuclear Chemistry》1995,190(2):299-313
Changes in the magnetic structure of Fe–Si–Al films due to Al and N ion implantation were studied by57Fe Conversion Electron Mössbauer Spectrometry (CEMS). The peaks of the magnetic sextets due to the crystalline films became broader by implantation with 5×1016 Al/cm2, suggesting the formation of amorphous phases. In the CEM spectrum of one sample with large grains implanted with 1×1017 Al/cm2 a crystalline -Fe phase appeared. N implantation with the same dose did not amorphize the sample but the components with high magnetic hyperfine fields were enhanced. 相似文献
64.
We consider percolation on the Voronoi tessellation generated by a homogeneous Poisson point process on the hyperbolic plane. We show that the critical probability for the existence of an infinite cluster tends to 1/2 as the intensity of the Poisson process tends to infinity. This confirms a conjecture of Benjamini and Schramm [5]. 相似文献
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