Acetonitrile

About: Acetonitrile is a research topic. Over the lifetime, 11298 publications have been published within this topic receiving 175275 citations. The topic is also known as: cyanomethane & ethyl nitrile.

Complexation of the cesium cation by macrocyclic polyethers in various solvents. A cesium-133 nuclear magnetic resonance study of the thermodynamics and kinetics of exchange

Abstract: The formation constants for the complexation of Cs/sup +/ in six solvents by three crown ethers, 18-crown-6, dibenzo-18-crown-6, and dicyclohexyl-18-crown-6, were studied at 25/sup 0/C by cesium-133 NMR techniques. The solvents used, in the approximate order of decreasing first complexation constant for all crown ethers, were pyridine, acetone, propylene carbonate, acetonitrile, N,N-dimethylformamide, and dimethyl sulfoxide. In all solvents, 18-crown-6 formed both 1:1 and 2:1 (ligand to metal) complexes with enough difference between the complexation constants that the second constant could be determined. The formation of 2:1 complexes by the other two crown ethers was also indicated in most solvents but the second complexation constant could only be measured for the dibenzo-18-crown-6 complex in pyridine. In many cases the first complexation constant was too large to measure by the NMR technique so that only lower bounds could be established. The rate of loss of the Cs/sup +/ ion from dicyclohexyl-18-crown-6 and from monobenzo-2,2,2-cryptand in propylene carbonate was measured as a function of temperature. The activation energy for the latter case (15 kcal mol/sup -1/) is substantially larger than for the crown ether complex (8.5 kcal mol/sup -1/). Although the chemical shifts of both Cs/sup +/ and its 1:1 complex with 18-crown-6more » are strongly solvent dependent, the chemical shift of the 2:1 complex is independent of solvent, indicating that in the ''sandwich'' complex the cesium ion is effectively shielded from the solvent.« less

Dielectric relaxation of electrolyte solutions in acetonitrile

Abstract: Complex permittivity spectra in the frequency range 0.95≤v (GHz)≤89 for acetonitrile and its solutions of LiBr, NaI, NaClO4, and Bu4NBr at 25°C show one Debye equation for the neat solvent whereas the superposition of a Debye process for the solute and a Cole-Cole distribution for the solvent is necessary to account for the dielectric relaxation behavior of the solutions. The reorientation of bulk acetonitrile is diffusive and only weakly coupled to viscosity. The number of solvent molecules irrotationally bound to the electrolyte is in good agreement with conventional solvation numbers for all electrolytes, when kinetic depolarization is assumed to be negligible. The solute relaxation process is dominated by the formation kinetics and reorientation of contact ion pairs. There is evidence for solvent-shared ion pairs in dilute NaClO4 solutions.

Isolation, characterization, and kinetics of formation of the cis and trans isomers of bis(acetonitrile)dichloroplatinum(II)

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.