Showing papers on "Acetonitrile published in 1983"
113 citations
TL;DR: Reverse-phase high-performance liquid chromatography resolution and recovery of cytochrome P-450 and bovine rhodopsin, both integral membrane proteins, and large peptides derived from P- 450 LM2 were enhanced by utilizing ternary solvents.
107 citations
TL;DR: In this article, it was shown that the unpaired electron in the mixed-valent complexes remains localised on one of the copper atoms in the dicopper(II) complexes.
Abstract: The synthesis, characterisation, and electrochemical studies of dicopper(II) complexes [Cu2L1][ClO4]2·nH2O of the macrocycle 7,11;19,23-dimetheno-9,21-dimethyl[1,5,13,17]-tetra-azacycloicosa-5,7,9,12,17,19,21,24-octaene-25,26-diol (H2L1), and of some 6,12,18,24-substituted (Me4; Prn4; Ph4; Ph, Me, Ph, Me) derivatives have been carried out. These compounds undergo sequential one-electron transfers at two different potentials. For all of these compounds, except for [Cu2L1][ClO4]2·2H2O, two reversible or almost reversible reduction steps have been observed in acetonitrile medium using a hanging mercury drop electrode. In the case of [Cu2L1][ClO4]2·2H2O, the second couple became obscured due to the presence of an adsorption phenomenon or secondary electrode reaction. However, in NN-dimethylformamide (dmf) medium, satisfactory voltammograms have been obtained only with [Cu2L1][ClO4]2·2H2O. The mixed-valent complexes are considerably more stable in acetonitrile than is [CuIICuIL1]+ in dmf. The potentials of the first reduction step (E1) remain practically invariant throughout the series and are independent of the extent of magnetic interactions in the dicopper(II) complexes. The potentials of the second reduction step (E2) vary with the alkyl and aryl groups present, and a linear plot has been obtained for E2vs. the Hammett function σm. On the basis of previously reported observations and the present study it is inferred that in acetonitrile medium the unpaired electron in the mixed-valent complexes remains localised on one of the copper atoms.
88 citations
TL;DR: In this article, the complex-formation constants of dibenzo-24-crown-8 (DB24C8) with alkali metal ions in acetonitrile and the solubility of DB 24C8 in methanol, acetitrile, and propylene carbonate were determined conductometrically and spectrophotically at 25 °C.
Abstract: Complex-formation constants (KML+) of dibenzo-24-crown-8 (DB24C8) with alkali metal ions in acetonitrile and the solubility of DB24C8 in methanol, acetonitrile, and propylene carbonate were determined conductometrically and spectrophotometrically at 25 °C, respectively. The KML+ value sequences of the alkali metal ions with DB24C8 are Na+>Cs+>K+=Rb+. Dibenzo-24-crown-8 shows no remarkable selectivity for the alkali metal ions in acetonitrile. Transfer activity coefficients of the DB24C8 complexes with alkali metal ions were calculated from these data and literature values of transfer activity coefficients of alkali metal ions. For the same alkali metal ion, the bulky DB24C8-alkali metal ion complex is more soluble in the aprotic solvents acetonitrile and propylene carbonate than in the protic solvent methanol as compared with the case of the alkali metal ion itself. The transfer activity coefficient of the DB24C8-alkali metal ion complex from methanol to acetonitrile is somewhat sensitive to the variation...
80 citations
TL;DR: In this paper, the acceptor properties of the solvents of substituted cyanoiron complexes were investigated and it was found that the parameter a was strongly influenced by the solvation characteristics of the ligands compared with those of the cyanides.
Abstract: The solvatochromism observed for substituted cyanoiron complexes depends on the acceptor properties of the solvents, according to v = vo + a(AN), where ν is the measured spectral charge transfer energy and AN refers to the acceptor number scale. The parameter a was found to be strongly influenced by the solvation characteristics of the ligands compared with those of the cyanides. In H2O+S mixed solvents, preferential solvation by water was observed where S was acetone or acetonitrile, but not when S was methanol, dimethylsulfoxide, dimethylformamide or related solvents.
66 citations
TL;DR: In this paper, three packings with the following surface composition were synthesized on LiChrosorb Si 100, d p 10 μm: [Cu(II) 3-(L -prolyl)propyl] + (packing I), [cu(II] 3-( L -hydroxyprolylpyl) propyl]+ (packing II) and [cu[2] 3-propyl spacer of the bonded ligand, etc., with remaining excess 3-iodopropyl groups (packing III).
63 citations
TL;DR: In this article, the realisation d'un transfert d'electrons controle electrochimiquement and la formation d'une paire d'ions intramoleculaire dans des ethers lariates nitrobenzene substitues.
Abstract: Donnees sur la realisation d'un transfert d'electrons controle electrochimiquement et la formation d'une paire d'ions intramoleculaire dans des ethers lariates nitrobenzene substitues. Preparation du (nitro-2phenoxy)-2-methyl-15-crown-5, de ses reactions electrochimiques en presence de Na + ClO 4 − et de la formation d'un complexe de ce compose avec Na +
60 citations
TL;DR: Zusammenfassung photolysis of [CpFe(CO) 3 ] + PF 6 − in CH 3 CN in the presence of 2-, 4-, or 6-electorn ligands gives [cpFeL n (NCCH 3 ) 3− n ] +PF 6 − (n = 1: L = CO, PPh 3, cyclohexene, dimethylthiophene; n = 2: L 2 = dppe or n = 3: L 3 = cyclooctatetraene, or three phospholes),
55 citations
TL;DR: In this article, the authors have shown that ion pair formation in 4-butyrolactone is very similar to that in propylene carbonate and acetonitrile.
48 citations
47 citations
TL;DR: In this paper, the vertical distribution of acetonitrile between 0 and 55 km altitude is calculated assuming that CH3CN is released at the Earth's surface and that the main loss process in the stratosphere is the reaction with hydroxyl radicals.
Abstract: The vertical distribution of acetonitrile between 0 and 55 km altitude is calculated assuming that CH3CN is released at the Earth's surface and that the main loss process in the stratosphere is the reaction with hydroxyl radicals. The influence of different possible surface concentrations is investigated. The role of the destruction of CH3CN by Cl, as well as the use of different eddy diffusion coefficients is briefly discussed. The results are compared with recent measurements of acetonitrile.
TL;DR: The newly synthesized [125I-Tyr10]monoiodoglucagon is shown to activate adenylyl cyclase in liver membranes with an EC50 between 5- and 8-fold lower than that of native glucagon.
Abstract: The synthesis of [125I-Tyr10]monoiodoglucagon from glucagon and carrier-free 125I using l,3,4,6-tetrachloro-3-6-diphenylglycouril (Iodogen) and its separation in pure form by reverse phase high pressure liquid chromatography (HPLC) over C18-μBondapak columns using two consecutive linear gradients between solvent A [40:60 mixture of methanol and 10 mM H3PO4 in H2O (pH adjusted to 3.0 with triethylamine)] and solvent B (50:50 mixture of acetonitrile and 0.1 M Tris-HCl, pH 9.0) is reported. The newly synthesized [125I] monoiodoglucagon is shown to activate adenylyl cyclase in liver membranes with an EC50 between 5- and 8-fold lower than that of native glucagon. Further, it binds specifically to sites on liver plasma membranes that have the characteristics of glucagon receptors in terms of gua-nine nucleotide sensitivity and rates of reaction. It is suggested that [125I-Tyr10]monoiodoglucagon is a suitable probe for studying structural and functional properties of glucagon receptors. (Endocrinology 113: 711, ...
TL;DR: O-Silylated ketene acetals have been added to activated enones possessing varying degrees of β-substitution under 15 kbar (1.5 GPa) pressure in acetonitrile at 20 °C to afford good to excellent yields of 1,4-adducts.
TL;DR: In this article, the magnetic relaxation rates of the four solutes acetone, acetonitrile, trimethylamine, and tetramethylurea in their aqueous mixtures are reported.
Abstract: Proton and deuteron magnetic relaxation rates of the four solutes acetone, acetonitrile, trimethylamine, and tetramethylurea in their aqueous mixtures are reported. For the normal and deuterated organic substances the water was D2O and H2O, respectively. The intermolecular relaxation rates were determined. Experimental results for the self-diffusion coefficients of trimethylamine and tetramethylurea in their aqueous mixtures are also reported. From these results and literature data the A parameter, A=(1/T1)inter·D1/c′1 being a criterion for association, was calculated. We obtained the result that only for the largest solute molecule, i.e. tetramethylurea, A showed the typical concentration dependence indicating solute-solute association. For the other three components self-association is not outside the range of the sensitivity of the present method.
TL;DR: A combination system of aluminum chloride-sodium iodide-acetonitrile effects aselective demethylation of aliphatic methyl ethers in the presence of aromatic methyl ether.
Abstract: A combination system of aluminum chloride-sodium iodide-acetonitrile effects aselective demethylation of aliphatic methyl ethers in the presence of aromatic methyl ether.
TL;DR: The results of the electron transfer mechanism of chlorophyll quenching were not in agreement with the conventional Marcus theory of electron-transfer reactions, as there is no evidence of quench constant as discussed by the authors.
Abstract: The quenching of chlorophyll a (Chl a) fluorescence hy a series of substituted benzoquinones. naphthoquinones and anthraquinones has been examined employing ethanol and acetonitrile as solvents. All quinones are good quenchers of fluorescence. There is an excellent linear relation between the Stern-Volmer quenching constants, K, and the polarographic half wave potentials (E12) of the quinones, with more oxidizing quinones being better quenchers. The quenching data are consistent with the excited state half wave potential of −1.31 eV predicted theoretically, demonstrating that the kinetically estimated value of the Chl a excited state reduction potential agrees with that expected on spectroscopic grounds. The results of quenching are not in agreement with the conventional Marcus theory of electron-transfer reactions, as there is no evidence of quenching constant. Kq. decrease vsΔG0 even for free energy changes nearly twice that expected for the onset of the Marcus inverted region. However, the kinetically estimated Kq values are in good agreement with the ones calculated by using the Rehm and Weller equation for fluorescence quenching by electron transfer. Our experimental results support the electron transfer mechanism of quenching proposed by Seely.
TL;DR: In this paper, the anodic oxidation of 1-naphthylamine (ArNH2) has been studied at the platinum electrode in DMSO by cyclic voltammetry and controlled-potential electrolysis.
TL;DR: In this article, aryl halide vapor and calcium metal vapor were found to give the corresponding arylscalcium halides, ArCaX (X = F, Cl, and Br), which gave a mixture of 1,1-di-phenylethanol and acetophenone.
TL;DR: In this paper, a laser flash photolysis of the title compound or the corresponding diazirine produces 1-naphthylcarbene, which readily reacts with nitriles (e.g. for acetonitrile k r = 4.6 × 10 5 M −1 s −1 ) to yield nitrile ylides that absorb strongly at 390 nm.
TL;DR: In this paper, the electrode reaction of the Mn(II)/Mn(Hg) system in acetonitrile and its mixtures with water has been studied and the charge transfer rate constants, diffusion coefficients and formal potentials were determined.
TL;DR: Laser photolysis of 1-naphthyldiazomethane or azirine 7 in acetonitrile gave the same transient absorption spectrum as discussed by the authors, and the transient from each precursor reacted with acrylonitrile with identical rate constants.
TL;DR: In this article, the IR spectra of seven hemiperchlorates of substituted pyridine N-oxides, which contain crystallographically symmetric and very short hydrogen bonds, have been investigated in dry nitromethane and acetonitrile-d3, and the following parameters obtained: η H − 1180 cm −1, A H A D − 1.67 and ηH η D −1.14.
TL;DR: In this paper, the kinetics of acetonitrile pyrolysis using an isothermal quartz tubular flow reactor at 720-1033 K and 1 atm were investigated.
Abstract: Detailed quantitative studies are reported on the kinetics of acetonitrile pyrolysis using an isothermal quartz tubular flow reactor at 720–1033 K and 1 atm. Pressure using flow rates, in nitrogen, of 2–200 ml min−1. The pyrolysis of several other nitriles (acrylonitrile, propionitrile, methacrylonitrile and benzonitrile) has also been investigated qualitatively by pyrolysis-gas chromatography.
TL;DR: A reversed phase ion-pairing liquid chromatographic method with UV detection at 214 nm was described for the determination of lincomycin A and lincommycin B in fermentation beers.
TL;DR: In this article, the kinetics of α-MMP homopolymerization and copolymerization were investigated in acetonitrile, using azobisisobutyronitrile (AIBN) as an initiator.
Abstract: α-Methylene-N-methylpyrrolidone (α-MMP) was synthesized and homopolymerized by bulk and solution methods. The poly(α-MMP) is readily soluble in water, methanol, methylene chloride, and dipolar aprotic solvents at room temperature. Thermogravimetric analysis of poly(α-MMP) showed a 10% weight loss at 330°C in air. The kinetics of α-MMP homopolymerization and copolymerization were investigated in acetonitrile, using azobisisobutyronitrile (AIBN) as an initiator. The rate of polymerization Rp could be expresed by Rp = k[AIBN]0.49[α-MMP]1.3. The overall activation energy was calculated to be 84.1 kj/mol. The relative reactivity ratios of α-MMP (M2) copolymerization with methyl methacrylate (r1 = 0.59, r2 = 0.26) in acetonitrile were obtained. Applying the Q-e scheme led to Q = 2.18 and e = 1.77. These Q and e values are larger than those for acrylamide derivatives.