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31.
Electrolysis of the system Ti(IV)–NH2OH–C6H6 in an 11 M H2SO4 solution shows that using an organic solvent (acetic acid, acetonitrile) during cathodically initiated amination of aromatic substrates permits the production of aromatic amines with the overall yield by hydroxylamine reaching 91%. Due to a chain mechanism of radical substitution, the benzene amination in electrolytes containing 5 M CH3COOH and 5.5 M CH3CN terminates largely upon consuming 70–75 and 50–55% of the charge required theoretically for a one-electron process. The maximum efficiency of electrochemical amination is observed at low hydroxylamine conversions and the overall current efficiency for mono- and disubstituted products of the benzene amination may exceed in these conditions 750%. 相似文献
32.
《Surface and interface analysis : SIA》2003,35(3):310-317
Carbonate is a somewhat enigmatic anion in static secondary ion mass spectrometry (SIMS) because abundant ions containing intact CO32? are not detected when analyzing alkaline‐earth carbonate minerals common to the geochemical environment. In contrast, carbonate can be observed as an adduct ion when it is bound with alkali cations. In this study, carbonate was detected as the adduct Na2CO3·Na+ in the spectra of sodium carbonate, bicarbonate, hydroxide, oxalate, formate and nitrite and to a lesser extent nitrate. The appearance of the adduct Na2CO3·Na+ on hydroxide, oxalate, formate and nitrite surfaces was interpreted in terms of these basic surfaces fixing CO2 from the ambient atmosphere. The low abundance of Na2CO3·Na+ in the static SIMS spectrum of sodium nitrate, compared with a significantly higher abundance in salts having stronger conjugate bases, suggested that the basicity of the conjugate anions correlated with aggressive CO2 fixation; however, the appearance of Na2CO3·Na+ could not be explained simply in terms of solution basicity constants. The oxide molecular ion Na2O+ and adducts NaOH·Na+ and Na2O·Na+ also constituted part of the carbonate spectral signature, and were observed in spectra from all the salts studied. In addition to the carbonate and oxide ions, a low‐abundance oxalate ion series was observed that had the general formula Na2?xHxC2O4·Na+, where 0 < x < 2. Oxalate adsorption from the laboratory atmosphere was demonstrated but the oxalate ion series also was likely to be formed from reductive coupling occurring during the static SIMS bombardment event. The remarkable spectral similarity observed when comparing the sodium salts indicated that their surfaces shared common chemical speciation and that the chemistry of the surfaces was very different from the bulk of the particle. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
33.
L. A. Chekulaeva I. A. Garbuzova V. V. Gavrilenko L. B. Danilevskaya V. A. Kotel'nikov 《Russian Chemical Bulletin》1996,45(9):2199-2202
Alkali metal salts of acrylamide C3H4NOM (M = Li, Na, and K) were synthesized for the first time by metallation of acrylamide with alkali metals, their alkyl derivatives, or hydrides. The structures of the compounds synthesized were studied by Raman and IR spectroscopy. Based on the results obtained, an ionic structure was proposed for the salts. The salts were tested as initiators of the anionic polymerization of acrylamide. The catalytic activity of C3H4NOM in the polymerization of acrylamide is not lower than that of the well known catalyst, KOBu1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 9, pp. 2316–2319, September, 1996. 相似文献
34.
Single crystals of NaKZnP2O7 were grown, and their crystal structure was determined by X-ray diffraction (space group P21/n, a = 12.585(5) Å, b = 7.277(5) Å, c = 7.428(5) Å, β = 90.00(5)°, Z = 4, 1916 F(hkl), R 1 = 0.0461). The structure contains a 3D tetrahedral zinc phosphate framework with a system of intersecting channels running along the b and c axes. The sodium and potassium atoms are coordinated to six and seven oxygen atoms, respectively, and reside inside these channels; the potassium cations, which are larger than the sodium cations, are located at channel intersections. 相似文献
35.
3-Diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II) — Synthesis and Structure Bis-(N′, N′-diethyl-N-benzoylselenoureato)nickel(II) reacts with diphosgene in benzene to 3-diethylamino-5-phenyl-1,2,4-diselenazolium-tetrachloroniccolate(II). Its structure is confirmed by RKSA and ESCA. The compound consists of cations, which are planar fivemembered rings and of tetrahedral tetrachloroniccolate(II) anions. The complex is isomorphic with 3-diethylamino-5-phenyl-1,2,4-dithiazolium-tetrachloroniccolate(II). 相似文献
36.
The enthalpy change on mixing solutions of methyl-substituted benzenesulfonic acids and their salts, with salts having a common
cation or anion, at constant ionic strength in mixtures of 1,4-dioxane with water, were measured at 25°C. The heat effects
of mixing solutions having a common anion increase almost linearly with the reciprocal value of the dielectric constant of
the solvent. The heat effects of mixing solutions having a common cation, which are all negative in water-rich solutions,
become endothermic after a certain value of the dielectric constant is passed. The results are discussed in terms of the solute-solvent
structural properties.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
37.
Hans-Jürgen Buschmann Achim Zielesny Eckhard Schollmeyer 《Journal of inclusion phenomena and macrocyclic chemistry》2006,54(3-4):181-185
The complex formation of the macrocyclic ligand hemicucurbit[6]uril with various salts has been studied in aqueous solution. Due to the low solubility of this ligand the formation of complexes results in an increase of the amount of ligand present in solution. From these measurements the stability constants of the complexes formed are calculated. Hemicucurbit[6]uril only forms cation complexes with cobalt(II), nickel(II) and the uranylion. All other cations examined e.g. silver(I), lead(II) and copper(II) do not form detectable complexes in aqueous solution. For a better understanding of the complexation behaviour some quantum mechanical chemical calculations are performed with Gaussian.Dedicated to Prof. H. Möhwald on the occasion of his 60th birthday. 相似文献
38.
A. N. Bovin V. I. Evreinov Z. V. Safronova E. N. Tsvetkov 《Russian Chemical Bulletin》1993,42(5):912-916
A number of monopodands havingo-diphenylphosphinyl terminal groups were synthesized by alkylating sodium derivatives of oligoethylene glycols witho-(bromomethyl)phenyldiphenylphosphine. The stability constants of the complexes of these ligands with alkali metal cations at 25 °C were determined conductometrically in a THF—chloroform solution (41, v/v). The complexing ability of monopodands with respect to the cations studied increases monotonically as the number of electron-donating sites increases (from 3 to 8) for all of the cations except Li+ and, to some extent, Na+. In the case of Li+ a smooth decrease in the stability of the complexes is observed. The monopodands obtained in this work differ drastically in this regard from their structural isomers, bis[o-(diphenylphosphinylmethyl)phenyl] ethers of oligoethylene glycols, which had been studied previously.For part 10, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 5, pp. 952–956, May, 1993. 相似文献
39.
The reaction of diethyl 3-ethoxycarbonyl-2-methyl-2-propenylphosphonate (1) with 3-methylbutanal (2) in the system solid MOH (M=K, Na, Li)-benzene without phase transfer catalysts affords ethyl 3,7-dimethyl-2,4-octadienoate with the ratios of 2E,4E stereoisomer (3a) to 2Z,4E-stereoisomer (3b) of 4456, 4654, and 6040 for KOH, NaOH, and LiOH, respectively. The similar tendency is observed when DMSO is substituted for benzene, although the proportion of3a in this case is 65% with any MOH used. The reaction of1 with2 in the presence of a stoichiometric amount of a quaternary ammonium hydroxide QOH (Q=NMe4, BnNMe3, (n-Bu)4N) in benzene gives higher3a3b ratios than those obtained with LiOH in the former reaction system. The increase in the content of 2E,4E-isomer3a is possibly due to the growth of the population of solvent-separated ion pairs or, generally, to the increase in the distance between the charge centers in the ionic intermediates on passing from KOH to LiOH and from [Me4N]OH to [(n-Bu)4N]OH. The position of the equilibrium betweenE- and Z-isomers of phosphonate1 under the reaction conditions (E-1Z-13565) is almost unaffected by the nature of the cation of the base.Part 5, see ref. 1.Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 6, pp. 1089–1094, June, 1993. 相似文献
40.
The localization of Terbium (Tb3+) cations binding to deionized bacteriorhodopsin (bR) has been studied by using spectroscopic methods. It was found that adding
Tb3+ cations to deionized bR affects the fluorescence lifetimes of tryptophan (Trp) in bR, the wavelength of fluorescence peak
shifts “blue” and the peak value of fluorescence decreases. It was also found that adding one Tb3+ cation to deionized bR can restore the purple state from its blue state obviously. The measurements of absorbance, fluorescence
and lifetime of fluorescence also show that when more than three Tb3+ cations are added, no further changes can be found. It is suggested that one Tb3+ specific binding site for the color-controlling is located on the exterior of the bR trimer structure to negatively charged
lipids near Trp-10 and Trp-12. Three Tb3+ cations binding per bR is needed for the regenerated bR. 相似文献