A rearrangement of transition metal acetylenic π-complexes into compounds with vinylidene n-ligands has been established. Compounds CpMn(CCHPh)-(CO)2 and Cp2Mn2(μ-CCHPh)(CO)4 with terminal and bridging phenylvinylidene (benzylidenecarbene) ligands respectively were obtained from the π-complexes CpMn(CO)2(PhCCR) where R H, Ph3Ge or Ph3Sn. Reactions leading to conversion of the terminal CCHPh group into a bridging ligand and vice versa were studied. Under the action of L Ph3P, (EtO)3P or (PhO)3P, substitution of CO groups in vinylidene complexes takes place and compounds CpMn(CCHPh)-(CO)L are formed. IR, 1H and 13C NMR spectra of the novel complexes are discussed. The data obtained indicate an electron-withdrawing property of the CCHPh ligand and stronger bonding of this ligand to the metal as compared with a CO group. 相似文献
Optimal conditions for the preparation of 9-ethyl-, 9,12-diethyl, 8,9,12-triethyl-, and 8,9,10,12-tetraethyl-o-carboranes under the action of EtBr on o-carborane in the presence of AICl3 were determined. The behavior of these o-carborane derivatives towards electrophilic and nucleophilic reagents was studied. The presence of four ethyl groups in positions 8, 9, 10, and 12 of the carborane polyhedron increases the electron density on the boron atoms in positions 4, 5, 7, and II to the point where they are able to enter into reactions of electrophilic substitution, and in positions 3 and 6 to the point that they become resistant to the action of nucleophilic reagents. Reactions of 1,2-dilithium-8,9,10,12-tetraethyl-o-carborane with various electrophilic reagents were studied.Translated fromIzvestiya Akademii Nauk, Seriya Khimicheskaya, No. 11, pp 2755–2763, November, 1996. 相似文献
Abstract A practical synthesis of racemic phosphinothricin and both of its enantiomers by the Michael addition of Schiff base of glycine to vinylphosphinate in the presence of sodium ethoxide or potassium hydroxide in ethanol was reported (I). 相似文献
The ability of alkylhydroxybenzenes to change the enzyme activity of hen egg white lysozyme and its efficiency in the catalyzed
hydrolysis of nonspecific substrates (chitin and yeasts) was demonstrated. A homolog, C7-AHB, was used as a modifier; this substance increased the lysozyme enzymatic activity over the entire studied range of concentrations.
The effect of C7-AHB concentration (0.125–4.0 mg/ml), species (initial or oxidized), and the time (1–24 h) of lysozyme incubation with C7-AHB at 25°C in 0.05 M phosphate buffer (pH 7.4) on the lysozyme activity were studied by differential scanning microcalorimetry,
as well as the thermodynamic parameters of its denaturation. The kinetic parameters of chitin hydrolysis by the C7-AHB-modified lysozyme were determined. 相似文献
Monodisperse nonmagnetic macroporous poly(glycidyl methacrylate) (PGMA) microspheres were synthesized by multistep swelling polymerization of glycidyl methacrylate, ethylene dimethacrylate and 2-[(methoxycarbonyl)methoxy]ethyl methacrylate (MCMEMA). This was followed (a) by ammonolysis to modify the microspheres with amino groups, and (b) by incorporation of iron oxide (γ-Fe2O3) into the pores to render the particles magnetic. The resulting porous and magnetic microspheres were characterized by scanning and transmission electron microscopy (SEM and TEM), atomic absorption and Fourier transform infrared spectroscopy (AAS and FTIR), elemental analysis, vibrating magnetometry, mercury porosimetry and Brunauer-Emmett-Teller adsorption/desorption isotherms. The microspheres are meso- and macroporous, typically 5 μm in diameter, contain 0.9 mM · g?1 of amino groups and 14 wt.% of iron according to elemental analysis and AAS, respectively. The particles were conjugated to p46/Myo1C protein, a potential biomarker of autoimmune diseases, to isolate specific autoantibodies in the blood of patients suffering from multiple sclerosis (MS). The p46/Myo1C loaded microspheres are shown to enable the preconcentration of minute quantities of specific immunoglobulins prior to their quantification via SDS-PAGE. The immunoglobulin M (IgM) with affinity to Myo1C was detected in MS patients.
Graphical abstract Monodisperse magnetic poly(glycidyl methacrylate) microspheres were synthesized, conjugated with 46 kDa form of unconventional Myo1C protein (p46/Myo1C) via carbodiimide (DIC) chemistry, and specific autoantibodies isolated from blood of multiple sclerosis (MS) patients; immunoglobulin M (IgM) level increased in MS patients.
Large enhancements have been observed in the sub-barrier fusion cross sections for Ti+Ni systems in our previous studies.
Coupled channel calculations incorporating couplings to 2+ and 3− states failed to explain these enhancements completely. A possibilty of transfer channels contributing to the residual enhancements
had been suggested. In order to investigate the role of relevant transfer channels, measurements of one- and two-nucleon transfer
were carried out for 46,48Ti+61Ni systems. The present paper gives the results of these studies. 相似文献