نتایج جستجو برای: nonaqueous
تعداد نتایج: 1290 فیلتر نتایج به سال:
Aqueous and nonaqueous AOT/n-heptane reverse micelles where characterized by UV-Visible and fluorescence spectroscopy of AO. The study shows the presence of the dimer in aqueous reverse micelles which is not present in the nonaqueous systems. It seems that there is a conversion of the dimer to monomer in the aqueous reverse micelles at high AOT concentration. In the nonaqueous systems, there is...
A two parameters equation of state (EOS) for nonaqueous electrolyte solutions system has been developed. The equation is in terms of Helmholtz free energy and incorporated with results of low density expansion of non-primitive mean spherical approximation. The EOS was tested for experimental data reported in literatures of 9 nonaqueous single electrolyte solutions of which the temperature was 2...
We demonstrate the redox potential calculation relative to the normal hydrogen electrode (NHE) in nonaqueous solution using a density functional theory-based molecular dynamics (DFT-MD) simulation. The calculation of the NHE in nonaqueous solution consists of two processes: the first step is the equilibrated simulation for a proton in nonaqueous solution to determine the space for inserting a p...
Frustrated Lewis pairs have found many applications in the heterolytic activation of H2 and subsequent hydrogenation of small molecules through delivery of the resulting proton and hydride equivalents. Herein, we describe how H2 can be preactivated using classical frustrated Lewis pair chemistry and combined with in situ nonaqueous electrochemical oxidation of the resulting borohydride. Our app...
A comparison of the use of aqueous and nonaqueous buffers in association with beta-CD for the chiral separation of (R)- and (S)-3,4-methylenedioxymethamphetamine and related compounds is described. The (R)- and (S)-isomers of 3,4-methylenedioxymethamphetamine (MDMA) and its major metabolite 3,4-methylenedioxyamphetamine (MDA) were prepared. Under aqueous and nonaqueous buffer conditions and bas...
Selected psychotropic drug standards have been chromatographed on RP18, CN and diol layers with a variety of aqueous and nonaqueous mobile phases. The effect of buffers at acidic or basic pH, acetic acid, ammonia and diethylamine (DEA) in aqueous mobile phases on retention, efficiency and peak symmetry was examined. Improved peak symmetry and separation selectivity for investigated compounds we...
Current trends in electrochemical studies of nonaqueous solutions are discussed with the emphasis on experimental approaches judged to be particularly promising for the future development of both fundamental and applied aspects of the field of solution chemistry. Topics include recent developments in the application of potentio— metric sensors to nonaqueous solutions, the potentialities of such...
This work presents a novel method for the accurate determining trans- and cis-resveratrol (3,5,4'-trihydroxystilbene) by nonaqueous capillary electrophoresis/fluorescence spectroscopy at 77 K. The proposed method permits not only the separation of resveratrol isomers, but also ensures that on-line spectra are readily distinguishable and unambiguously assigned. The experimental results also indi...
We examined the stability of emulsions of oil in several nonaqueous polar liquids using commercially available nonionic surfactants. Stable nonaqueous emulsions were only obtained with formamide and dimethylsulfoxide. Hydrogen bonding, and not polarity, appears to be the important factor determining the emulsifying power of a solvent. Ostwald ripening plays a much more important role in the sta...
Metal oxide nanoparticles can be fabricated under high control via nonaqueous sol-gel synthesis. This route has been shown to lead to highly crystalline, uniform nanostructures, which explains the high and growing interest it is receiving. The underlying mechanisms are, however, so far only rudimentarily understood on a molecular scale. Here, we applied in situ FTIR spectroscopy and other techn...
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