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31.
The geminal regioselectivity observed in the ene reaction between singlet oxygen and alkenes with anion-stabilizing groups is rationalized on the basis of a perepoxide intermediate, in which in analogy to the nucleophilic attack on protonated epoxides, the perepoxide is opened preferentially at the C---O bond weakened by the substituent. 相似文献
32.
Wilfredo Hernndez Evgenia Spodine Andres Vega Rainer Richter Jan Griebel Reinhard Kirmse Uwe Schrder Lothar Beyer 《无机化学与普通化学杂志》2004,630(10):1381-1386
The N‐acyl thiourea complexes bis[N,N‐diethyl‐N′‐(p‐nitrobenzoyl)‐thioureato]copper(II) ( 1a,1b ) and bis(N,N‐diphenyl‐N′‐benzoylthioureato)copper(II) ( 2a,2b ) crystallize in each case in two modifications. X‐ray structural analysis shows that 1a and 1b are cis‐trans isomers. This is very unusual for N‐acyl thioureato complexes because with exception of one platinum(II) complex up to now only cis complexes have been found. In contrast X‐ray structural analysis of both forms 2a and 2b of the other complex shows no cis‐trans pair. Both modifications are cis complexes. In solution both isomers of the copper(II) complexes are observable by EPR spectroscopy. 相似文献
33.
Several 2-substituted-3(2H)-cinnolinones have been synthesized by a ring expansion of the respective 1-substituted-2-indolinones via an oxidative-rearrangement with t-butyl hypochlorite. 相似文献
34.
Summary A program is described which calculates the number of effective plates and the coating efficiency over the entire range of a test chromatogram. The peak widths at half height are derived by assuming a Gaussian peak shape. The interpolated peak width at k=4 is used for computing a standardized number of effective plates. Plate height, column permeability, overall performance and a novel parameter called sampling efficiency are calculated from 5 other figures — i. e. carrier gas code, pressure drop, column length, column temperature and particle size.Dedicated to Dr. Leslie S. Ettre for his 60th birthday. 相似文献
35.
O. Seidelmann L. Beyer Grit Zdobinsky R. Kirmse F. Dietze R. Richter 《无机化学与普通化学杂志》1996,622(4):692-700
N,N-Dialkyl-N′-ferrocenoylthioureas and Ferrocene-1,1′ -dicarbonic-acid-di-N,N-dialkylthioureides as Ligands for Transition Metals: Synthesis, Acid-Dissociation Constants, X-Ray Structure Determination, and EPR-Single Crystal Investigation Reaction of ferrocenoylisothiocyanate or ferrocene-1,1′ -dicarbonic acid -diisothiocyanate with secondary amines gives N,N-dialkyl-N′ -ferrocenoylthioureas or the respective ferrocene-1,1′-dicarbonic acid-di-N,N-dialkyl-thioureides. The former yield neutral complexes with transition metal ions (Ni2+, Cu2+, Co3+, Pt2+, Fe3+). The acid dissociation constants of the ligands were determined. The EPR spectra of a bis-(N,N-dinbutyl-N′-ferrocenoylthioureato)copper(II) single crystal are discussed. The X-ray structure determination of ferrocene-1,1′-dicarbonic acid-di-N,N-diethyl-thioureide and its different behaviour against Ni2+ and Cu2+ is presented. 相似文献
36.
Zusammenfassung Durch den Einsatz zweiwertiger Ionen in der wäßrigen Subphase kann die Packungsdichte gespreiteter Monoschichten wasserunlöslicher Tenside pH-abhän-gig erhöht werden. Ergebnisse für Octadecylamin auf einer Lösung von Natriumhydrogensphosphat werden angegeben.
Mit 2 Abbildungen 相似文献
Summary The packing density of spread monolayers of waterinsoluble surface-active agents can be increased by use of bivalent ions in the aqueous subphase. Results for octadecyl amine spread on a solution of sodium hydrogen phosphate are given.
Mit 2 Abbildungen 相似文献
37.
To screen for organic pigments, like fringelites or porphyrins, in sediments and fossil specimen, a simple diffuse reflectance UV-vis spectroscopic determination was developed. In contrast to common inorganic pigments, like Fe2O3, these pigments exhibit well-structured characteristic absorption peaks which allow their recognition. This method was then used to identify fringelite H in a non-crinoidSolenopora species from the Jurassic. Reflectance FTIR spectroscopy proved not to be useful for this purpose. 相似文献
38.
3-Diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II) — Synthesis and Structure Bis-(N′, N′-diethyl-N-benzoylselenoureato)nickel(II) reacts with diphosgene in benzene to 3-diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II). Its structure is confirmed by RKSA and ESCA. The compound consists of cations, which are planar fivemembered rings and of tetrahedral tetrachloroniccolate(II) anions. The complex is isomorphic with 3-diethylamino-5-phenyl-1,2,4-dithiazolium-tetrachloroniccolate(II). 相似文献
39.
E. Hensel R. Groetzschel E. Richter 《Journal of Radioanalytical and Nuclear Chemistry》1988,122(2):321-326
Silicon nitride hard coatings on tool steel produced by ion beam mixing following sputter or vapour deposition were investigated by RBS and Vickers microhardness measurements. Atomic mixing in the coating/steel interface region resulting in an improved adhesion and in a significant increase of the microhardness of the surface layers was found. Ion beam mixing with gas ions and high fluences leads to blistering of the implanted atoms in the silicon nitride layer. 相似文献
40.
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