Showing papers on "Acetonitrile published in 1990"
TL;DR: Au cours de ce congres, des aspects theoriques et experimentaux sur la solubilite ont ete abordes as discussed by the authors, a.k.a.
Abstract: Au cours de ce congres, des aspects theoriques et experimentaux sur la solubilite ont ete abordes
208 citations
01 Jan 1990-International Journal of Radiation Applications and Instrumentation. Part B. Nuclear Medicine and Biology
TL;DR: Resin-supported [18F]fluoride ion has been prepared and applied to a rapid, convenient synthesis of [ 18F]FDG and overall yields presently averaging above 50%.
172 citations
TL;DR: In the absence of acid catalysts, the glyoxal hemiacetal derivative 2,3-dihydroxy-1,4-dioxane reacts with benzylamine or 4-pyridylmethylamine in acetonitrile solvent to produce 9,10-bis(arylmethyl)9, 10-diaza- 1,4,5,8-8-tetraoxaperhydroanthracenes 13a,b.
Abstract: The condensation of glyoxal with benzylamine leads to 2,4,6,8,10,12-hexabenzyl-2,4,6,8,10,12-tetraazatetracyclo(5.5.0.0{sup 5,9}.0{sup 3,11})dodecane (2a) in solvents such as acetonitrile or methanol with formic acid catalyst. Six phenyl-substituted derivatives of 2a have been prepared and the scope of the reaction has been examined. Intermediates 1,2-bis(benzylamine)-1,2-ethanediol (6) and N,N{prime}-dibenzyl-1,2-ethanediimine (7) have been prepared and the mechanism of their conversion to 2a is discussed. In the absence of acid catalysts, the glyoxal hemiacetal derivative 2,3-dihydroxy-1,4-dioxane reacts with benzylamine or 4-pyridylmethylamine in acetonitrile solvent to produce 9,10-bis(arylmethyl)9,10-diaza-1,4,5,8-tetraoxaperhydroanthracenes 13a,b.
168 citations
TL;DR: Correlation entre les structures chimiques des different polyimides and leurs proprietes redox is investigated in this paper, where the authors show that there is a correlation entre the two.
Abstract: Correlation entre les structures chimiques des differents polyimides et leurs proprietes redox
154 citations
TL;DR: In this article, the kinetics of pyrolysis of pyridine dilute in argon have been studied in a single-pulse, shock tube, using capillary column GC together with GC/MS and FTIR spectroscopy for product determination, over the temperature range of 1,300-1,800 K and total pressures of 7-11 atm.
Abstract: The kinetics of pyrolysis of pyridine dilute in argon have been studied in a single-pulse, shock tube, using capillary column GC together with GC/MS and FTIR spectroscopy for product determination, over the temperature range of 1,300-1,800 K and total pressures of 7-11 atm. At the lower end of the studied temperatures, cyanoacetylene was found to be the principal nitrogen-containing product. At elevated temperature hydrogen cyanide predominated. Other major products were acetylene and hydrogen. Several sources of HCN were identified in the system. An important source of HCN at high temperatures is the addition of H atoms to cyano compounds, especially cyanoacetylene, but also acetonitrile and acrylonitrile which are produced in the pyrolysis. The pyrolysis is a chain process initiated principally by C-H bond fission to form o-pyridyl. A 58-step reaction model is presented and shown to substantially fit the observed profiles of the major product species.
151 citations
TL;DR: In this paper, the complex permittivity spectra of amides formamide, N-methylformamide and N-dimethylformamide, as well as dipolar aprotic solvents acetonitrile, propylene carbonate and dimethylsulfoxide were determined in the frequency range 0.95-89 GHz.
138 citations
TL;DR: In this article, the photooxidations of branched acyclic alkanes and cycloalkanes by a range of polyoxotung states varying in charge density, ground-state redox potential, acidity, and other properties were examined in detail.
Abstract: The photooxidations of exemplary branched acyclic alkanes and cycloalkanes by a range of polyoxotungstates varying in charge density, ground-state redox potential, acidity, and other properties were examined in detail. The organic products generated in these reactions depend on the polyoxometalate used, and in particular on the ground-state redox potential of the complex. Under anaerobic conditions acyclic branched alkanes yield principally alkenes, while cycloalkanes yield principally alkenes and dimers. Alkyl methyl ketones, derived in part from reaction with acetonitrile solvent, and isomerized alkanes are produced with some alkane substrates. Under aerobic conditions, autoxidation, initiated by radicals generated in the photoinduced redox chemistry, is observed. Under aerobic conditions the polyoxotungstates with formal redox potentials more negative than {minus}1.0 V vs Ag/AgNO{sub 3}(CH{sub 3}CN), such as W{sub 10}O{sub 32}{sup 4{minus}} and W{sub 6}O{sub 19}{sup 2{minus}}, photochemically dehydrogenate branched acyclic alkanes in high selectivity to {alpha}-olefins and the least substituted alkenes, products heretofore undocumented in photooxidation reactions catalyzed by polyoxometalates.
137 citations
TL;DR: Measurements on mixed acetone-N-methylformamide solvents showed that the solubility of oxygen does not vary with solvent composition in a predictable manner.
114 citations
TL;DR: In this paper, a method for azidolysis of 1,2 epoxides with NaN3 in acetonitrile, by means of metal salts, is described.
96 citations
TL;DR: In this article, the coordinatively unsaturated nitrosonium cation is reduced at the reversible redox potential, as determined by the cyclic voltammetry of either the salt NO + BF 4 − on the initial negative scan or nitric oxide in acetonitrile.
Abstract: The coordinatively unsaturated nitrosonium cation is reduced at the reversible redox potential, as determined by the cyclic voltammetry of either the salt NO + BF 4 − on the initial negative scan or nitric oxide on the initial positive scan in acetonitrile. The marked solvent dependence of E° in other aprotic media (such as dichloromethane and nitromethane) correlates linearly with Gutmann's DN parameter for solvent donicity
95 citations
TL;DR: The C≡N stretching frequency is affected by change in the solvent and also by a change in concentration in the same solvent, and the degree of Fermi resonance interaction changes with change in solvent.
Abstract: The C≡N stretching frequency, vC≡N, is affected by change in the solvent and also by change in concentration in the same solvent. In the case of acetonitrile, vC≡N is in Fermi resonance with the combination tone (δsym. CH3 + vC-C), and the degree of Fermi resonance interaction changes with change in the solvent. With the exception of dimethyl sulfoxide, unperturbed vC≡N for acetonitrile exhibits a pseudo-linear correlation with the acceptor number of the solvent.
TL;DR: In this paper, the electrochemical polymerisation of pyrrole-substituted cobalt tetraphenylporphine complex on a vitreous carbon electrode has been performed in acetonitrile+tetrabutylammonium tetrafluoroborate solution.
TL;DR: The 1H NMR spectra of the free fluoride anion in CH3CN and CD3CN solutions showed that the F− anion can abstract a proton from CH 3CN resulting in the slow formation of the bifluoride and acetonitrile anions as mentioned in this paper.
TL;DR: In this article, two pyrrole monomers substituted at the nitrogen atom by appropriate alkyl ammonium chains were electropolymerized in acetonitrile onto electrode surfaces.
TL;DR: The method presented is a combination of kinetically controlled peptide synthesis ( giving high reaction rates) and thermodynamically controlled peptides synthesis (giving stable reaction products).
TL;DR: In this article, the synthesis of fluorocompounds by sulfide electrochemical oxidation using Et 3 N.3HF as fluorinating agent is described, which is less efficient than chemical oxidation.
TL;DR: In this article, the mixing of equal volumes of 0.2 mmol dm-3 1 -benzylnicotinamide ion and 2 mmol Dm−3 cyanide ion results in the immediate formation of a transient absorption band at 375 nm which can be ascribed to a charge transfer complex.
Abstract: The mixing of equal volumes of 0.2 mmol dm–3 1 -benzylnicotinamide ion and 2 mmol dm–3 cyanide ion results in the immediate formation of a transient absorption band at 375 nm which can be ascribed to a charge–transfer complex. This complex disappears within ca. 0.2 s with the formation of the 1,6-addition product which, in turn, is rapidly converted into the thermodynamically more stable 1,4-adduct. Methyl substitution at the 6-position of the nicotinamide ring inhibits the formation of the 1,6-adduct, resulting in an increase in the lifetime of the charge–transfer complex. Subsequently a mixture of the 1,4-cyanide adduct and, most likely, the 1,2-adduct is formed. Rate effects with variation of substituents in the 1-benzyl group reveal that charge-transfer complex formation is counter-productive to the formation of addition products.
TL;DR: The bis(acetonitrile)dichloroplatinum(II) obtained by the standard procedure has been shown to be a mixture of the cis and trans isomers the composition of which depends upon the experimental conditions used as discussed by the authors.
Abstract: The bis(acetonitrile)dichloroplatinum(II) obtained by the standard procedure has been shown to be a mixture of the cis and trans isomers the composition of which depends upon the experimental conditions used. The pure isomers have been characterized by i.r. and 1H n.m.r. spectroscopy and the conditions for the preferential obtainment of each isomer have been explored. Kinetic measurements have shown that the formation of the cis isomer is kinetically favoured in the reaction of [PtCl3(NCMe)]– with a second molecule of acetonitrile, indicating that the chlorine ligand exerts a trans-labilizing effect greater than that of acetonitrile.
TL;DR: In this article, an aromatic aldehyde and bis(3-ethyl-4-methyl-2-pyrrolyl)-methane were obtained from acetonitrile in the presence of a catalytic amount of trichloroacetic acid, followed by p-chloranil oxidation.
TL;DR: In this paper, the properties of poly(N-alkyl-3,6-carbazolediyl)s (PCZSs) were investigated in the presence of a catalytic Ni(0)-based system.
TL;DR: Iodine is an effective promoter for the carbonylation of primary and secondary amines to ureas using palladium acetate as the catalyst and a base (e.g. K2CO3) in acetonitrile as discussed by the authors.
Abstract: Iodine is an effective promoter for the carbonylation of primary and secondary amines to ureas using palladium acetate as the catalyst and a base (e.g. K2CO3) in acetonitrile (3 h at 95 °C and 2.7 ...
TL;DR: In this paper, a dielectric film of poly(phenylene oxide), PPO, is formed by the anodic electropolymerization of tetramethylammonium phenoxide from acetonitrile onto Pt or Au electrodes.
TL;DR: In this paper, a two-electron reduction of dioxygen with an NADH model compound, 10-methylacridan (AcrH 2 ), occurs efficiently in the presence of metalloporphyrins and perchloric acid in acetonitrile at 298 K.
Abstract: Two-electron reduction of dioxygen with an NADH model compound, 10-methylacridan (AcrH 2 ), occurs efficiently in the presence of metalloporphyrins and perchloric acid in acetonitrile at 298 K. Overall four-electron reduction of dioxygen by AcrH 2 has also been made possible by adding iodide ion to the metalloporphyrin-catalyzed system. The catalytic mechanisms are discussed on the basis of detailed kinetics and the kinetic isotope effects for the overall CoTPP + -catalyzed reduction of dioxygen by AcrH 2 as well as for each half catalytic cycle, the oxidation of AcrH 2 by CoTPP + and the reduction of dioxygen by CoTPP in the presence of HClO 4
TL;DR: In this paper, the photo-induced charge separation (CS) process in the 1,2,4,5-tetracyanobenzene (TCNB)-aromatic hydrocarbon charge transfer (CT) complexes in various polar solvents was investigated.
Abstract: Femtosecond and picosecond laser photolysis and time-resolved transient absorption spectral studies have been made-to elucidate the photoinduced charge separation (CS) process in the 1,2,4,5-tetracyanobenzene (TCNB)-aromatic hydrocarbon charge-transfer (CT) complexes in various polar solvents. We have confirmed that, in a polar solvent such as acetonitrile, solvent reorientation can induce CS with a time constant shorter than 1 ps to a considerable extent but not completely. Moreover, we have demonstrated that, for the complete CS leading to the ion-pair formation, further intracomplex structural change and solvation, which take place with a time constant (τ CS ) of several picoseconds to 30 ps depending on the natures of the electron-donating aromatic hydrocarbon and the polar solvent, are necessary
TL;DR: Etude de l'oxydation et de la dimerisation d'un colorant cyaninique sur une electrode de platine dans l'acetonitrile.
Abstract: Etude de l'oxydation et de la dimerisation d'un colorant cyaninique sur une electrode de platine dans l'acetonitrile
TL;DR: An efficient photoinduced cyanation of various alkaloids by Me 3 SiCN in acetonitrile, sensitized by N,N'-dimethyl-2,7-diazapyrenium-bis-(tetrafiuoroborate) (DAP 2+, 2 BF 4 − ), is described in this paper.
TL;DR: In this paper, the 77Se NMR spectra of solutions with stoichiometries near those for SeX2 and Se2X2 (X = Br, Cl) formation in aprotic solvents of varying basicity have been recorded.
TL;DR: In this paper, a cyclization of the latter with SeCl 4 gave 6-X-4,5,7- trifluoro-2,1,3-benzoselenadiazoles whose reduction led to the corresponding 1,2-diamino- benzenes.