Showing papers on "Acetonitrile published in 1978"
TL;DR: In this paper, the influence of the surface coverage of the bonded phase on polar group selectivity in reversed-phase liquid chromatography has been explored, using a series of synthesized n -octy bonded phases.
224 citations
150 citations
TL;DR: In this article, the authors measured the apparent molar volumes and heat capacities for both water and the organic components in terms of enhanced water-water interactions and as being the result of inter-component interaction.
Abstract: Densities and molar heat capacities have been measured for the following binary systems at 29815 K: water + formamide, water +N,N-dimethylacetamide, water + dimethylsulphoxide and water + acetonitrile over the whole mole fraction range From these data apparent molar volumes and heat capacities have been calculated for both water and the organic components The volumes have been discussed in terms of enhanced water–water interactions and as being the result of inter-component interaction The volume of water infinitely diluted in the various solvents might be well understood from the packing of hard sphere molecules Similar reasoning cannot be applied to the heat capacities Most of the curves are typical for weakly hydrophobic solutes, while the apparent molar heat capacity curve of formamide in water + formamide resembles that of hydrophilic solutes Finally, the apparent molar heat capacities of water at infinite dilution in the various solvents are unexpectedly high
141 citations
TL;DR: A facile synthesis of HN[PO(C6H5)2]2(3), HN [PS[C 6H5]2[4], Hn[PS[PSe(C 6 H5)]2[5] and N[PNH2[C6 H5] 2Br(6) is described in this article.
Abstract: A facile synthesis of HN[PO(C6H5)2]2(3), HN[PS(C6H5)2]2(4), HN[PSe(C6H5)2]2(5) and N[PNH2(C6H5)2]2Br(6) is described. The reaction of 1,1,1,3,3,3-hexamethyldisilazane and chlorodiphenylphosphine yields bis(diphenylphosphino)imine which then reacts with H2O2 in THF to give 3; with sulfur in toluene to give 4, with potassium selenocyanate in acetonitrile, followed by HCl/acetone, to give 5 and with bromine in dichloromethane, followed by ammonia to give 6.
104 citations
TL;DR: In this article, a facile synthesis of substituted dinuclear carbonyls M 2 (CO) 9 L and M 2(CO) 8 L 2 (M = Mn, Re; L = triphenylphosphine, pyridine, acetonitrile) in good yields is described.
81 citations
75 citations
TL;DR: It was found that most of the polyamines circulating in blood are localized in the erythrocytes, their content in normal human blood being spermidine 14.1 +/- 3.1, and spermine 8.4 +/- 2.8 nmoles/ml packed ery Throcytes.
71 citations
TL;DR: In this paper, a chemically bonded diamine phase was used to chelate Cd(II) and a relatively hydrophobic chelating agent, C12-dien, was added to an acetonitrile-water mobile phase containing Zn(II).
67 citations
59 citations
TL;DR: In this paper, the authors studied the stability of cyclic polyethers in methanol and acetonitrile by the polarographic method and found that they are sometimes comparable or higher than the stability constants of polyhedra with the potassium ion.
56 citations
TL;DR: In this article, the ternary liquid-liquid equilibria for two ternaries w-hexane-ethanolacetonitrile at 40°C and water-acetate-ethyl acetate at 60°C were obtained.
Abstract: Liquid-liquid equilibrium data are obtained for the two ternary systems w-hexane-ethanolacetonitrile at 40°C and water-acetonitrile-ethyl acetate at 60°C. Vapor-liquid equilibria for the two miscible binaries of each ternary system are also determined. The measured ternary liquid-liquid equilibria are compared with those predicted from the constituent binary data alone by use of various activity coefficient equations.
TL;DR: In this paper, a chemical-electrochemical approach for the determination of the positions of coupling in the dimeric one-electron reduction products of 1-alkylpyridinium ions in acetonitrile is described.
TL;DR: In this article, the one-electron reduction of 1,4-benzoquinone, 1, 4-naphthoquinone and 9, 10-anthraquinone in acetonitrile solution were measured at Pt, Au and graphite electrodes by rapid scan cyclic voltammetric methods.
TL;DR: In this article, the polarity of the solvent and the availability of protons in the solvent have been investigated for photo-sensitized I-ion oxidation by singlet oxygen.
Abstract: — Iodide ion oxidation by singlet oxygen is found to be influenced by two properties of the solvent. One is the polarity of the solvent and the other is the availability of protons in the solvent. By suitable choice of solvents and solvent mixtures both kinds of effects have been studied. In water-methanol mixtures the reaction is found to be facilitated in more polar medium. In isodielectric media as obtained by mixtures of acetonitrile and methanol the reaction is repressed with increase in the aprotic component (CH3CN) in the solvent. The same effect is observed in the DMSO-H, O mixtures. In heavy water the reaction rate is doubled and the effect fits well into the proposed kinetic scheme involving singlet oxygen for photosensitized oxidation of I- by anthracene sulphonates.
TL;DR: Raman and infrared spectral data have been collected forp-dioxane and solvated and bound nitrate ions for Zn(NO3)2/p-Dioxane/water systems.
Abstract: Raman and infrared spectral data have been collected forp-dioxane and solvated and bound nitrate ions for Zn(NO3)2/p-dioxane/water systems. It is concluded that Zn2+ is preferentially solvated by water and that this aquation is also responsible for a lower concentration of ion pairs than is found for methanol/Zn(NO3)2 solutions for which the dielectric constant of the bulk solvent is similar. Values of K1 (M−1), the association constant for Zn(NO3)+, are 0.22±0.02 (2/1 solvent,D=12.6) and 0.071±0.01 (4/1 solvent,D=33.0). The log K1 against 1/D plot is not linear.
TL;DR: Polarography, cyclic voltammetry and coulometry reveal that a catalytic reduction of the tetraalkylammonium cation, R4N+, of the supporting electrolyte is involved in the electrochemical reduction of triphenylphosphine (TPP) and its oxide (TPPO) in aprotic solvents such as acetonitrile, dimethylformamide and hexamethylphosphoramide as discussed by the authors.
TL;DR: In this paper, the difference between reversible half-wave potentials observed in acetonitrile and aqueous solutions was discussed in terms of solvation energies of the oxidized and reduced forms.
Abstract: In tetraethylammonium perchlorate-acetonitrile solution, [Ru(acac)3] was reversibly reduced at the dropping mercury electrode to [Ru(acac)3]− with a conditional electrode reaction rate-contsant estimated to be ca. 0.2 cm s−1 or larger. The reduced form was stable in the solution under an inert gas atmosphere. In aqueous solutions, [Ru(acac)3] was reduced reversibly when the depolarizer concentration was less than 0.07 mol m−3 at 25 °C. At higher depolarizer concentrations, [Ru(acac)3] molecules were adsorbed onto the mercury surface, and the free molecules in solution were reduced through the adsorbed layer at a smaller rate; the adsorbed layer was removed at a certain negative potential, and the reversible reduction took place normally at the bare surface. The difference between reversible half-wave potentials observed in acetonitrile and aqueous solutions was discussed in terms of solvation energies of the oxidized and reduced forms.
01 May 1978
TL;DR: In this paper, a depolarisierte Rayleigh scattering experiments on neat acetonitrile and carbon disulfide as well as on mixtures of these liquids with carbon tetrachlorkohlenstoff are reported.
Abstract: Depolarized Rayleigh scattering experiments on neat acetonitrile and carbon disulfide as well as on mixtures of these liquids with carbon tetrachloride are reported. The collective reorientational correlation time τLS has been determined which is then compared with the single particle correlation time τS. From the comparison information on an orientational structure factor g(2), which is closely related to the Kirkwood g-factor of polar fluids, can be obtained. Combination of g(2) and Kirkwood g-factor results shows that a preferred antiparallel alignment is the most probable orientational structure in acetonitrile. For CS2 a Kirkwood g-factor cannot be defined due to symmetry. Here the experiments indicate a preferred parallel arrangement of neighbouring molecules.
Es wird uber depolarisierte Rayleighstreuexperimente an reinem Acetonitril und Schwefelkohlenstoff wie an Mischungen dieser Flussigkeiten mit Tetrachlorkohlenstoff berichtet. Die Korrelationszeit τLS fur kollektive Umorientierung wurde bestimmt und mit der Korrelationszeit τS fur Einzelteilchen verglichen. Aus dem Vergleich erhalt man Information uber einen Orientierungsstrukturfaktor g(2), welcher eng mit dem Kirkwoodschen g-Faktor polarer Flussigkeiten zusammenhangt. Kombination des g(2)- und des Kirkwoodschen g-Faktors zeigt, das eine antiparallele Anordnung die wahrscheinlichste Orientierungsstruktur in Acetonitril ist. In CS2 bildet g(2) aus Symmetriegrunden den ersten sinnvollen Strukturfaktor. Hier deutet sich eine bevorzugte Parallelstellung benachbarter Molekule an.
Patent•
20 Dec 1978
TL;DR: In this article, Fe-Sb-Bi-O x promoted with a wide variety of different elements have been found to be especially useful in the ammoxidation of olefins to nitriles such as acrylonitrile and methacrylynitrile.
Abstract: Oxide complex catalysts comprising Fe-Sb-Bi-O x promoted with a wide variety of different elements have been found to be especially useful in the ammoxidation of olefins to nitriles such as acrylonitrile and methacrylonitrile. Not only are the desired nitriles obtained with high yields when these catalysts are used, but also the production of unwanted liquid byproducts such as acrolein, acrylic acid and acetonitrile is significantly reduced.
TL;DR: In this paper, the standard heterogeneous rate constants of single electron transfer reactions involving several quinonoid molecules at platinum and gold electrodes were determined using a cyclic voltammetric method.
TL;DR: In this article, double fluorescence of DMAPh and MCDMA in CH 3 CN and CH 2 Cl 2 has been observed and analyzed in terms of reversible excited state isomerisation of the primary excited form b * to the strongly polar rotamer a *.
TL;DR: Cyclic voltammetry of the title borabenzenecobalt complexes at a platinum electrode in acetonitrile reveals reversible one-electron oxidation to the respective cations and reversible oneelectron reduction to the anions.
TL;DR: In this article, the reaction of propylene with nitric oxide for the synthesis of acrylonitrile has been studied over nickel oxide supported on alumina as a catalyst, and the kinetic studies reveal that the mechanism of the reaction is of the "redox" type.
TL;DR: In this article, a one-term Drude's equation was used to analyze the x-ray diffraction data, and the result showed a variation of dispersion parameters with different solvents in accordance with the observed CD changes.
Abstract: Circular dichroism, optical rotatory dispersion, and viscosity of hyaluronic acid at various solvents compositions, concentrations, and pH values have been studied. The data show a large change in the molecular properties in organic/water solvents such as ethanol, p-dioxane, or acetonitrile/water at pH ⩽ pKa. At this pH range of aqueous solution, hyaluronic acid shows a CD minimum near 210 nm whereas in the presence of organic solvent it exhibits a strong negative dichroism (below 200 nm) and a positive band near 226 nm. It undergoes a sharp, cooperative transition with respect to pH and solvent. The observed CD features are assigned to the π-π* and n-π* transitions of the amide and carboxyl chromophores. The ORD results show a gradual blue shift of trough at 220 nm with increasing magnitude of rotation when the organic solvents and hydrogen ion concentrations are increased. A one-term Drude's equation was used to analyze the ORD data, and the result show a variation of dispersion parameters with different solvents in accordance with the observed CD changes. The intrinsic viscosity of hyaluronic acid in mixed solvent at pH 2.6 is lower than that of aqueous solution. All the observed property changes of hyaluronic acid are reversed on addition of foramide in mixed solvents indicating that the hydrogen bonds are involved in this transition. The observed spectroscopic and hydrodynamic features are attributed to a conformational change of hyaluronic acid in a mixed solvent involving intramolecular hydrogen bonding between the acetamido and carboxyl groups. The possible conformational state of hyaluronic acid in solution under various conditions is discussed in terms of the reported helical structure of hyaluronic acid from x-ray diffraction studies.
TL;DR: In this paper, the best combination of 2- O -acyl group, solvent, time, temperature, and 1-O -sufonyl group was found to give high yields with high stereoselectivity.