摘要:

AbstractThe reaction mechanism of the thermolysis of azetidine to form ethylene and methylenimine has been studied byab initioSCF MO method at STO–3G and 3–21G levels. Two possible stepwise pathways are explored. One is the breaking of C—C bond as the first step, while the other is the breaking of C—N bond. All the stationary points on the potential energy surface (PES) are fully optimized. MP2/3–21G single point calculations on all stationary points and MCSCF/STO‐3G computations for some stationary points are also carried out. The calculations indicate that azetidine decomposes via biradicaloid intermediates and the cleavage of C—N bond is preferable to tha

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100301

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractFlow microcalorimetry was used to study the adsoption of anionic alkyl surfactants from aqueous solutions onto silica. It is found that for alkyl sulfate systems the strength of adsorption interaction increases with increases of the alkyl chain length and decreases as temperature rises. The adsorption depends only on monomer concentration of the solution even above the critical micelle concentration (cmc). The assumption is made that the adsorption involves only a transfer of monomers from bulk to surface phase. A different adsorption mechanism is operative for the alkyl carboxylate.

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100302

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractThe thermodynamic ionization constantK° ofp‐nitrophenol in {10 mass% ethanol‐water} mixed solvent is derived from measurements of its absorption spectrum and pH by the two methods: Debye‐Hückel extrapolation and polynomial approximation proposed by us in suitable buffer solution at constant ionic strength from 0.1 to 2.0 mol · kg−1at 298.2 ± 0.2 K. The results from both methods are pK° = 7.406 and 7.415, respectively. The effect of medium on the ultraviolet spectra ofp‐nitrophenol has

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100303

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractPolyperfluorobutyne‐2 (PPFB), a conjugated polymer, was characterized with IR, UV‐VIS, fluorescence spectraetc.The electrical conductivities of the polymer doped with various dopants were investigated. The effect of the molecular structure of PPFB on the electrical properties was discus

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100304

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractThe catalytic activity for the synthesis of methanol from carbon dioxide and hydrogen was measured on various binary and ternary catalysts containing copper oxide under a pressure of 10 atm. Among these samples the catalysts, CuO/ZnO/γ‐A1203, demonstrated the highest activity and selectivity to methanol; MnO, as third component, had no promotional effect on the activity of methanolformation. Based on a simple power rate law the apparent activation energy estimation and partial pressure dependence measurement were accomplished over eight catalysts. The activation energies varied from 40 to 120 kJ/mol depending on the composition of catalysts. The rates of methanolformation to be 0.3 — 0.9 order in H2and about 0.1 — 0.2 order in CO2were re

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100305

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractA nickel(II) complex containing both dithiolato and phosphine ligands, Ni2(PPh3)2(edt)2(edt = SCH2CH2S2‐), has been prepared and characterized by X‐ray diffration. The complex crystallizes in the triclinic system, space groupP‐1, witha= 10.693(3),b= 17.457 (6),c= 10.606 (3) Å, α = 102.84(2), β = 96.49 (2), γ = 82.56(3);V= 1906.8 Å3;Dc= 1.439 g·cm−3forZ= 2; the final conventionalRwas 0.052 based on 3338 observed reflections. Nickel atoms are linked by two sulfur atoms from two edt ligands with the Ni—Ni distance of 2.893 Å, and each Ni atom is coordinated by one phosphorus atom and three sulfur atoms with a square‐planar geometry, where the average length of Ni—S bond is 2.180 Å and Ni—P bond 2.188 Å. The UV‐Vis and1H NMR spect

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100306

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractA polynuclear complex containing a monomer of Cu(II)‐Zn(II) heterobinuclear unit was synthesized and characterized by IR spectra and magnetic moment. The crystal and molecular structure of the complex, CuZnC19H24Cl4N2O2, was determined by X‐ray diffraction, it crystallized in monoclinic,P21/m, α= 8.812 (2),b= 15.972(3),c= 8.831(1) Å, β = 114.33(1)°,V= 1132.4Å3,Z= 2,De= 1.710 g/ cm3,γ(MoKα) =0.71073 å, μ = 25.227 cm−1,R= 0.051.Rw= 0.063 for 1130 observed reflections withI>3α(1). The coordinated octahedra of Cu(II) and tetrahedra of Zn(II) via bridging CI atoms form a single chain polynuclear complex. The Cu, Zn and bridging Cl atoms are located on the crystallographic symmetry planemwhich is perpendicular to 2N and

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100307

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractThe effects of electrolytes, alcohols, and urea on the aggregation of SDS, CTAB, and Triton X‐100 at 25°C have been investigated by fluorescence probing of pyrene. Both electrolytes and alcohols reduce the critical micelle concentration (CMC) of the ionic surfactants, while the effect of the former is more pronounced. It is shown that the effects of electrolytes mainly depend on the concentrations and especially the valence of the opposite charge ions, and only slightly depend on the same charge ions in respect of ion aggregate of micelle. The logarithm of CMC is not linearly correlated with the concentrations of the counter ion or the electrolytes. The results are rationalized in terms of Hartley's model. Propanol increases the CMC of TX‐100, while electrolytes and urea do not. In all the three kinds of surfactant micelles the excitation spectrum of pyrene slightly red‐shifts (ca.4 nm) from that in water, but is not affected by the additives. The micropolarity of the environment in which pyrene molecule resides in SDS micelle decreases with the increase of the concentrations of electrolytes. This is not the case when alcohols and urea were added to SDS or to TX‐100. It is suggested that the addition of electrolytes would result in more orderly orientation of SDS molecules. It is the binding strength of the counter ions that dominates the effects of additives on the aggregation of sur

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100308

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractThe CO2laser induced room temperature reactions of CH3CF2H or another protium‐donor CH3CHClCH3with chlorine‐atom donors (Z—Cl) CFCl2CF2Cl, CF2CCl3, CFCl3or CF2Cl2, have been investigated. Some of these reactions can yield two important monomers (CF2= CH2and CF2= CFCl) for fluoropolymers simultaneously. The yield dependence of these two alkenes on experimental conditions has been studied. A laser‐initiated chain process is supported by identification of Z—H intermediates in these

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100309

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY

摘要:

AbstractThe photo‐SRN1 reaction of (+)‐camphor and aryl halides was investigated in order to estimate the stereochemistry of the coupling step of aryl radicals with a nucleophile. The ratio ofendotoexoproducts determined by1H NMR and CD spectra was found to be 99:1. MNDO calculations of the orbital parameters showed a favorable one‐sided overlap of the enolate ion with the SOMO of aryl radical. In addition, fragmentation of (ArX)−was found to be related to the energy of SOMO of

ISSN:1001-604X    

DOI:10.1002/cjoc.19920100310

出版商:Wiley‐VCH Verlag GmbH&Co. KGaA, Weinheim    

年代:1992

数据来源: WILEY