The obstruction effect for tracer-diffusion of Mn2+ ions in the presence of different supporting electrolytes (LiCl, NaCl, KCl, CsCl) at various concentrations has been studied at 25 °C using the zone diffusion technique. It has been observed that the obstruction effect determined in terms of increases with concentration of the electrolyte. Further, for a given concentration it is found to decrease with increasing charge density of the cation. We also report here on the effect of temperature on obstruction and found that is constant over the temperature range studied (25–45 °C). These observations are explained on the basis of competitive hydration between ions and agar macromolecules. 相似文献
Determination of fluoride at trace level is important for the specification analysis of nuclear fuel samples. This is generally accomplished by pyrohydrolytic separation followed by ion selective electrode potentiometry. In the present work, a method has been developed for the determination of fluoride by radiometric assay of181Hf back-extracted from thenoyltrifluoracetone (HTTA) in benzene.181Hf back-extracted is proportional to the concentration of fluoride. 相似文献
A novel 1,4-N→O migration of a disubstituted phenyl ring was observed during N-methylation of a bicalutamide derivative, (2S)-2-(tert-butyldimethylsilanyloxy)-N-(4-cyano-3-trifluoromethylphenyl)-3-(4-fluorophenoxy)-2-methylpropionamide, in the presence of CsF-Celite/acetonitrile and desilylation of (2S)-2-(tert-butyldimethylsilanyloxy)-N-(4-cyano-3-trifluoromethylphenyl)-3-(4-fluorophenoxy)-2,N-dimethylpropionamide in tetra-n-butylammonium fluoride/THF. Both NMR and X-ray analysis confirmed the structure of the 1,4-N→O disubstituted phenyl ring migrated product. 相似文献
The activation energy for the diffusion of ZnSO4 as a function of electrolyte concentration is computed by least squares fitting of the diffusion coefficient data obtained at various temperatures in the Arrhenius equation. It is observed that the activation energy decreases with increasing concentration of the electrolyte. This observation is accounted for on the basis of Wang's model. Further, the obstruction effect caused by the agar macromolecules in the diffusion path of ZnSO4 uis also determined at these concentrations by varying the gel concentration at 25°C., The obstruction effect expressed in terms of a found to decrease with ZnSO4 concentration and explained on the basis of competitive hydration of diffusing ions and agar molecules. 相似文献
Macrocyclic ligands N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]succinoyl dicarboxamide (H2L1) and N,N-bis[2,6-diiminomethyl-4-methyl-1-hydroxyphenyl]sebacoyl dicarboxamide (H2L2) were synthesized and characterized by various spectral techniques. Macrocyclic di- and tetra-homonuclear phenoxo bridged CuII, CoII, NiII, ZnII, CdII and HgII complexes have been synthesized through the template method by using the precursors 2,6-diformyl-4-methylphenol, succinoyldihydrazide/ sebacoyldihydrazide and respective metal chlorides in 2:2:2/2:2:4 ratio respectively. The synthesized complexes were characterized by i.r., n.m.r., u.v.-vis., FAB-mass, e.s.r., magnetic susceptibility and elemental analyses data. The elemental analyses and FAB-mass spectral data have justified the dinuclear and tetra nuclear structure for the complexes of the ligands H2L1 and H2L2 respectively. The observed low magnetic moment values revealed the existence of antiferromagnetic spin exchange interaction operating between the two metal centers. Electronic data suggested the octahedral geometry for NiII complexes and square pyramidal geometry for CuII, CoII, ZnII, CdII and HgII complexes of both the ligands. The CuII, CoII and ZnII complexes of both the ligands have shown good antifungal activity against Aspergillus niger and Fusarium oxysporum and medium to weak antibacterial activity against Escherichia coli and Staphylococcus aureus when compared to the standard drugs Grisefulvin and Ciprofloxacin respectively. 相似文献
A straightforward process for synthesis of hybrid porous electrode material composed of reduced graphene oxide (rGO) and copper sulfide (CuS) with layered structure on the stainless steel substrate is developed. As-synthesized hybrid electrode shows hexagonal crystal structure of CuS with 77 m2 gm−1 specific surface area and 22 nm average pore size. The specific capacitance obtained with rGO-CuS5 hybrid electrode is 1201 F g−1 at the sweep rate of 5 mV s−1 in 1 M LiClO4 aqueous electrolyte. The majority of charge stored by diffusion-controlled process indicates benefits of layered structures for solid-state energy storage. The rGO-CuS5-based hybrid symmetric supercapacitor delivers a specific capacitance (Cs) as high as 109 F g−1 at a sweep rate of 5 mV s−1 with polyvinyl alcohol (PVA)-LiClO4 gel electrolyte. Also, the specific energy of 44 Wh kg−1 and specific power of 1.4 kW kg−1 with 87% stability after 6000 cycles at an applied current of 5 mA are obtained. The simple process of synthesis of layered hybrid electrode material for flexible supercapacitor promises its use in smart textile and wearable electronic devices.
A green, highly efficient, and eco-friendly protocol for Knoevenagel–Michael addition reaction is reported in Chickpea leaf exudates (CLE) as a naturally sourced biosurfactant. The reactions between dimedone/4-hydroxycoumarins and a variety of aryl aldehydes were carried out in presence of CLE to afford diketodiols/biscoumarins. The synthetic pathway complies with several key requirements of green chemistry principles such as the employment of natural feedstock as green reaction media, ambient temperature, atom economy along with natural biosurfactant type Bronsted acids, and recyclable and biodegradable catalyst which led to a 28-fold increase in molar efficiency versus industrial standard protocols. Its dynamic phase is confirmed by the optical microscopy technique and critical micelle concentration measurement. The notable advantages of the present protocol were simple work-up procedure, high yield within short reaction time, easy separation of products, avoiding tedious column chromatography thus making the protocol environmentally friendly, sustainable, and economical.
Osmotic vapor pressure and density measurements have been carried out for binary aqueous and ternary aqueous solutions containing
a fixed concentration of 18-crown-6 (0.2 mol⋅kg−1) and ammonium chloride or ammonium bromide at 298.15 K. The concentration of the ammonium salts was varied between 0.02 to
0.5 mol⋅kg−1. The measured water activities were used to obtain the activity coefficient of water and the mean molal activity coefficient
of the ions in binary as well as ternary solutions. Using the method developed by Patil and Dagade reported earlier in this
journal and the McMillan-Meyer pair and triplet Gibbs energy interaction parameters, the thermodynamic equilibrium constant
(K) for the 18-crown-6:NH4+ complexes were determined. It is observed that the nature and polarizability of anions play important roles in imparting
stability to the complexed species. The log10K values for the 18-crown-6:NH4+ complexed species are lower than for the complexes involving alkali metal ions such as K+. The volume of complexation for the studied systems obtained from the apparent molar volumes of ammonium halides in ternary
solutions are positive and of smaller magnitude than those reported for complexation with alkali ions. The results are further
discussed in terms of water structural effects, complex formation, the role of counter anions and hydrophobic interactions. 相似文献
A method for controlled potential coulometric determination of neptunium by titration with internally electrolytically generated iron(II) has been developed. The method involves oxidation of Np to Np(VI) by Ce(IV), destruction of excess of Ce(IV) by NaNO2 followed by determination of neptunium by reduction of Np(VI) to Np(IV) by internal generation of Fe(II). The method was employed for various neptunium solution samples and a precision of ±0.25% at 2–5 mg level of neptunium was obtained. 相似文献