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31.
The shift of the uncoupled OH stretching frequency of water (from its free state position) in crystal hydrates has been plotted against a parameter r0 obtained by subtracting the H-bond (OH...Y) length from the sum of the free state ionic radii of O and Y. From an analysis of this curve it is inferred that MOw coordination in hydrates reduces the ionic size of water oxygen and its effect on the OH stretching frequency is opposite to that of H-bonding. 相似文献
32.
Prem C. Srivastava Marvin L. Tedjamulia Furn F. Knapp 《Journal of heterocyclic chemistry》1986,23(4):1167-1169
The synthesis and tissue distribution studies in rats of tetra[3H]-hydroberberine ([3H] 2 ) and 8-(p-[125I]iodobenzyl)tetrahydroberberine ([125I] 6 ) are described. Compound 2 was synthesized by sodium borohydride reduction of berberine hydrochloride ( 1 ). Treatment of berberine hydrochloride with p-bromo-benzylmagnesium bromide gave 8-(p-bromobenzyl)dihydroberberine ( 4 ) which after sodium borohydride reduction and iodine-125 bromine exchange gave [125I] 6 . The unsubstituted tetrahydro compound [3H] 2 showed significantly higher brain uptake (2.2% dose/gm after 5 minutes) as compared to the corresponding 8-substituted derivative [125I] 6 . Both radiolabeled compounds washed out from the brain relatively quickly. 相似文献
33.
2-Diethylaminoethanethiol hydrochloride is proposed for spectrophotometric determination of palladium(II). The sensitivity of the reaction is 0.0085 smg/cm2 and the yellow colored complex shows absorption maxima at 258 mμ and 303 mμ. Color development is slow in the cold but complete after heating for 10–15 min. The optimum pH range is 3.5 to 5.5 and the system adheres to Beer's law between 0.2 and 16.8 p.p.m. of palladium. The average and maximum relative standard deviations were 0.60% and 1.40% respectively. Interferences due to other platinum metals were studied and a procedure is suggested for the simultaneous determination of rhodium and palladium. 相似文献
34.
The various thermodynamic parameters for the periodate oxidation of six anilines, viz. aniline, p-chloroaniline, p-ethoxyaniline, o- and p-methoxyanilines and p-methylaniline have been reported and discussed. The validity of the isokinetic relationship and various linear free energy relationships (LFERs) have been tested and discussed. An attempt has been made to correlate these findings with the mechanism operative in these reactions. 相似文献
35.
V. D. Anand J. P. Srivastava G. S. Deshmukh 《Fresenius' Journal of Analytical Chemistry》1962,191(5):321-329
Summary The polarographic behaviour of nickel and cobalt in the mixed base electrolytes, urea-pyridine and urea-hydrazine has been studied. The effect of pH, concentration of supporting electrolyte and the presence of various other ions was investigated. Well defined polarograms for both the elements were obtained at pH 6.0 and 5.0 respectively. Attempts were made to utilize these observations in the separation of the two cations. While the difference in E
1/2 of the ions in urea-pyridine was greater than –0.3 volts that in urea-hydrazine was about –0.2 volts or slightly less even under the optimum conditions. In a mixed solution the waves for Co and Ni were therefore well developed and separated in the former base electrolyte. The polarograms in urea-hydrazine were, however, of little analytical use because of the washing away of the Ni wave due to the presence of even small amounts of cobalt.
Zusammenfassung Das polarographische Verhalten von Nickel und Kobalt in Harnstoff-Pyridin- und Harnstoff-Hydrazinlösung wurde untersucht und der Einfluß des pH-Wertes, der Leitsalzkonzentration sowie der Gegenwart verschiedener anderer Ionen festgestellt. Bei pH 6,0 bzw. 5,0 wurden für beide Elemente gut ausgebildete Polarogramme erhalten. Es wurde versucht, die erhaltenen Ergebnisse zur Trennung der beiden Ionen zu benutzen. In Harnstoff-Pyridinlösung beträgt der Unterschied der beiden Halbstufenpotentiale mehr als –0,3 V und man erhält gut ausgebildete und voneinander getrennte Stufen. In Harnstoff-Hydrazinlösung dagegen beträgt der Unterschied nur –0,2 V oder etwas weniger, selbst unter optimaler Bedingungen, und die Ni-Stufe wird schon durch kleine Kobaltmengen beeinträchtigt.相似文献
36.
Ananya Banik Theodosios Famprikis Michael Ghidiu Saneyuki Ohno Marvin A. Kraft Wolfgang G. Zeier 《Chemical science》2021,12(18):6238
The development of high-performance inorganic solid electrolytes is central to achieving high-energy- density solid-state batteries. Whereas these solid-state materials are often prepared via classic solid-state syntheses, recent efforts in the community have shown that mechanochemical reactions, solution syntheses, microwave syntheses, and various post-synthetic heat treatment routines can drastically affect the structure and microstructure, and with it, the transport properties of the materials. On the one hand, these are important considerations for the upscaling of a materials processing route for industrial applications and industrial production. On the other hand, it shows that the influence of the different syntheses on the materials'' properties is neither well understood fundamentally nor broadly internalized well. Here we aim to review the recent efforts on understanding the influence of the synthetic procedure on the synthesis – (micro)structure – transport correlations in superionic conductors. Our aim is to provide the field of solid-state research a direction for future efforts to better understand current materials properties based on synthetic routes, rather than having an overly simplistic idea of any given composition having an intrinsic conductivity. We hope this review will shed light on the underestimated influence of synthesis on the transport properties of solid electrolytes toward the design of syntheses of future solid electrolytes and help guide industrial efforts of known materials.Influence of synthesis and processing on the nature of ultimate product and the ionic transport properties of superionic conductors. 相似文献
37.
A visible light promoted, photoredox catalysed, green one-pot approach for the alkylation of amine substrates with sp2 carbon has been developed. This eosin Y based organic transformations, can behave as an effective direct hydrogen-atom transfer catalyst for coupling reaction. The proposed strategy includes simple procedure which can make adduct product with sp2 carbon. This eosin Y based photocatalytic hydrogen-atom transfer strategy may hold great potential for diverse functionalization of a wide range of native CH bonds in an economical and sustainable manner. 相似文献
38.
A new, simple, precise, and rapid high-performance thin-layer chromatographic method was developed for the determination of 6 benzodioxanes in Piper mullesua extract: 1',3'-benzodioxole-5'-(2,4,8-triene-isobutyl nonanoate), 1',3'-benzodioxole-5'-(2,4,12-triene-isobutyl tridecanoate), fargesin, sesamin, asarinin, 1',3'-benzodioxole-5'-(2,4,8-triene-methyl nonanoate). The ingredients were separated on a precoated Silica Gel 60 F254 plate with a solvent system of toluene-acetone (92 + 8). The 6 benzodioxanes were well separated and easily identified in this chromatographic system. The separated benzodioxanes were visualized by color development with a spray reagent consisting of 1 g vanillin dissolved in 100 mL H2SO4-ethanol (5 + 95, v/v). Quantitation was performed by scanning the spots and comparing the integrated areas of compounds in samples with those of standards. Recoveries from samples spiked with known amounts of the benzodioxanes were excellent. The results were comparable with those estimated by liquid chromatography. 相似文献
39.
40.
Summary m-Phenylenedioxydiacetic acid gives a white precipitate with thorium even in the absence of an electrolyte which is quantitative up toph 4. Be2+, Mg2+, Ca2+, Zn2+, Pb2+ and Mn2+ ions are removed by single precipitation and Al3+, UO2
2+ and trivalent cerite earth ions are removed by double precipitation. Sn2+, Sn4+ and Cr3+ ions interfere.Part II: See. Z. analyt. Chem.165, 343 (1959). 相似文献