The present paper is a continuation of comprehensive study regarding to synthesis and properties of pyrazoles and their derivatives. In its framework an experimental and theoretical studies of thermal decomposition of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline were performed. It was found, that the decompositions of the mentioned pyrazoline system in the solution and at the melted state proceed via completely different molecular mechanisms. These mechanisms have been explained in the framework of the Molecular Electron Density Theory (MEDT) with the computational level of B3LYP/6-31G(d). A Bonding Evolution Theory (BET) examination of dehydrochlorination of the 3,3-diphenyl-4-(trichloromethyl)-5-nitropyrazoline permits elucidation of the molecular mechanism. It was found, that on the contrary for most known HCl extrusion processes in solution, this reaction is realised via single-step mechanism. 相似文献
The goal of our studies was to determine the nature of interactions between catalytic active samples, such as polypyrrole (PPy) doped with: chloride anions, heteropolyacids such as H5PMo10V2O40, or H4SiW12O40, and oxygen particles. In order to reveal the mechanism of the linkage between the catalysts and oxygen we provided the electron paramagnetic resonance (EPR) measurements of synthesized samples in O2 and N2 flow. Moreover, the X-ray photoelectron spectroscopy (XPS) measurements were performed to show the properties of doped heteropolyacids and the state of nitrogen in polypyrrole matrix. The results of EPR studies of PPy(Cl), PPy(H4SiW12O40), PPy(H5PMo10V2O40) samples, show that the polypyrrole doped with chloride anions interacts much easier with oxygen than polypyrrole doped with heteropolyacids (in the above given order, of preference with the most active polypyrrole system first). It correlates with XPS results, which show that a molybdenium-vanadium anion is more reduced than a silicon-tungsten one. The redox reactions of heteropolyacids involve the oxidation-reduction of the conjugated polymer chain, leaving no or little place for interactions with oxygen. Polypyrrole doped with H4SiW12O40 shows some oxygen sensitivity as observed in the EPR studies, as opposed to polypyrrole doped with H5PMo10V2O40, which is in line with the XPS results. 相似文献
We present an update of Garland's work on the cohomology of certain groups, construct a class of groups many of which satisfy
Kazhdan's Property (T) and show that properly discontinuous and cocompact groups of automorphisms of (4,4) or (6,3)-complexes
do not satisfy Property (T).
Submitted: September 1996, final version: March 1997 相似文献
Kinetics studies of the condensation of model hydroxyl-terminated oligosiloxanes, pentamethyldisiloxane-1-ol (MDH) and heptamethyltrisiloxane-1-ol (MD2H), catalysed by protic complex of tetrakis(pentafluorophenyl)borate in the toluene solution were performed. The dominating reaction was condensation, which was accompanied by disproportionation of oligosiloxanols. Water released in the condensation forms separate dispersed phase, but the phase separation and the presence of water does not affect the rate of the polycondensation. Both processes, condensation and disproportionation, show analogous kinetic laws being first order in silanol and half order in catalyst. They exhibit also similar values of activation parameters. The kinetics are explained by the formation of a reactive protic complex of silanol with borate being in fast preequilibrium with an unreactive complex including two borate molecules and the silanol molecules. The equilibrium lies to the side of the unreactive borate complex. 相似文献
Mesoporous silica material of MCM-41 type was synthesized by co-condensation
of highly concentrated octyltriethoxysilane (OTEOS), octadecyltriethoxysilane
(ODTEOS) and tetraethoxysilane (TEOS). The obtained hybrid materials were
characterized using XRD, TG-DSC and low temperature adsorption/desorption
of nitrogen. It was shown that the applied method of synthesis allows to obtain
silica of MCM-41 type with a high degree of hydrocarbon saturation. 相似文献
Summary Endohedral and exohedral metallofullerenes, including metal-doped fullerenes, organometallic fullerenes and fullerene metal complexes, are described in the context of their syntheses and properties. 相似文献
Chiral α,ω-diesters react under high-pressure conditions (10 kbar) with α,ω-diamines to give chiral cyclic tetraamides of C2-symmetry. The complexation properties of tetraamides towards alkali metal cations (Li+, Na+, K+, Rb+ and Cs+) were estimated on the basis of ESI-MS spectra. 相似文献
In this paper, several methods of hydrophobization of cotton fabrics using the thio-ene click reaction were compared. Durable, superhydrophobic textiles were obtained in an easy way. Various variants of functionalized silsesquioxanes were used for the hydrophobization of fabrics. The synthesis of bifunctional silsesquioxanes (RSiMe2O)4(ViSiMe2O)4Si8O12 and (RSiMe2O)4(R’SiMe2O)4Si8O12 were performed via hydrothiolation of silsesquioxane derivative (ViSiMe2O)8Si8O12. Alkoxysilyl, alkyl and fluoroalkyl moieties were introduced as functional groups. Samples were prepared using four methods, differing in the modification method and the number of stages. During the research, fabrics were modified via (a) the dip-coating process, (b) carrying out thiol-ene click reactions directly on the surface of the fabric and (c) using both of these methods. The hydrophobicity of the fabric was evaluated by measuring the Water contact angle (WCA). The obtained samples were also examined using infrared analysis (FT-IR), Scanning electron microscope (SEM), and Elemental analysis (SEM–EDS). All analyses were performed before and after the washing process in order to verify the stability of the performed modifications.
Microsolvation of the [Ni(acac)(tmen)]+ complex by a series of aliphatic n-alcohols (Solv) has been studied in ClCH2CH2Cl solutions by spectrophotometry. Based on the changes in the electronic spectrum of the afore-mentioned complex, observed under the influence of any alcohol, the equilibrium constants for the formation of the [Ni(acac)(tmen)Solv]+ and [Ni(acac)(tmen)Solv2]+ species have been computed according to the algorithm presented in this work. It was found that, in all the systems studied, the stability of five-coordinated [Ni(acac)(tmen)Solv]+ is higher than that of octahedral [Ni(acac)(tmen)Solv2]+. The resulting values are discussed in terms of the Lewis basicity of alcohols. 相似文献