Basicity of neutral organic superbases with vinamidine structure in gas phase and acetonitrile: a density functional theory study

The gas‐phase proton affinities (PAs) for a set of molecules with vinamidine structure are considered and their basicities in acetonitrile. It is shown that introducing double bonds to the imidazoline rings at the proton attachment site resulted in decrease in PA of the parent vinamidine. The increase in PA can be obtained by inducing modifications to the imidazoline ring at the junction of two diazepinylium rings. Placing methyl and dimethylamino substituents on the perimeter of the molecule further increased their gas‐phase PAs. Studied vinamidine molecules are superbases, which possess PA values in the range between 261.0 and 284.2 kcal mol^–1 in the gas phase and pK_a values of 24.6–31.9 units in acetonitrile. Dismembering proton attachment site by opening the two diazepinylium and imidazoline rings resulted in the largest drop in PA values, indicating its importance in constraining the positions of imino nitrogen atoms in the neutral form of the molecule. Vinamidine molecules studied here present important pieces of the ladder of highly basic organic compounds for they possess accessible vinamidine molecular framework. Copyright © 2012 John Wiley & Sons, Ltd.     

On the relation between the formal atomic charges and total molecular energies

It is shown that the total SCF molecular energies are fairly well reproduced by the sum of electrostatic potentials exerted on the nuclei calculated in the point-charge approximation. Hence, there is a very simple relation between the total energies and formal atomic charges in molecules. The semiempirical SCC-MO charges have the same performance as the ab initio DZ ones.     

Terpolymerization of acrylonitrile,styrene, and 2,3-dibromopropyl acrylate

The terpolymerization of acrylonitrile with styrene and 2,3-dibromopropyl acrylate in emulsion and dimethyl formamide solution was investigated. Polymerizations, when stopped at low conversions, yielded terpolymers that showed good agreement between experimental and theoretical copolymerization composition data, calculated from the Alfrey-Goldfinger equation. The relationship between monomer feed and terpolymer compositions is displayed on triangular coordinate graphs proposed by Slocombe. By using a computer program the lines of unique composition and binary azeotropic composition for both systems were established. In the case of emulsion polymerization the azeotropic ternary point was determined at a molar ratio for acrylonitrile/styrene/2,3-dibromopropyl acrylate of 0.27/0.61/0.12. The experimental results of emulsion terpolymerization fit the calculated curves satisfactorily over a wide range of monomer compositions up to high conversions. The influence of 2,3-dibromopropyl acrylate on the thermal and flammability characteristics of the terpolymers is described.     

Terpolymerization of acrylonitrile,styrene, and 2,4,6-tribromophenyl acrylate

Acrylonitrile was terpolymerized with styrene and 2,4,6-tribromophenyl acrylate in aqueous emulsion and dimethylformamide solution. Experimental terpolymerization data agreed well with calculations based on the Alfrey–Goldfinger equation. Triangular coordinate graphs show the feed/terpolymer relationships; the lines of unique and binary azeotropic compositions were identified. No points of true azeotropic composition were found but a “pseudo-azeotropic” region was recognized. The experimental data of the emulsion terpolymerization experiment agreed well with the theoretical curves over a wide range of monomer compositions up to high conversions. Incorporation of 2,4,6-tribromophenyl acrylate in the terpolymer decreased the thermal stability but improved the flame retardancy of the terpolymers.     

Slater-orbital molecular integrals by numerical Fourier-transform methods. II. Four-center integrals over is orbitals

The four-center nonplanar electron repulsion integrals over 1s Slater-type atomic orbitals are considered by a numerical Fourier-transform method. It is shown that the highly oscillating integrand appearing in the Fourier inversion formula could be successfully treated by using Tchebyscheff quadrature. The resulting formulas are thoroughly discussed with particular emphasis on their numerical features and convergence properties. It follows that the aforementioned integrals may be calculated with a good accuracy with a moderate amount of computing time.     

Elektrophorese der halogenokomplexe von Hg(II), Bi(III), Cd(II), Pb(II) und Cu(II): Abhängigkeit der beweglichkeiten von der konzentration des metallions

The dependence was investigated of the mobilities of the chloro-complexes of Hg(II), Cd(II), Pb(II) and Cu(II) on the concentration and the volume of the metal salt solution applied, the experiments being carried out in relatively low concentrations of hydrochloric acid (0.1N, 0.5N and 1N) This dependence is considerable in base clectrolytes of low concentration (Iess than 1N HCl) and insignificant in the case of higher concentrations (greater than 1N HCl)On increasing the concentration and volume of the metal salt applied, the Caitionic mobility of the zones increases and the amonic mobility decreasesUnder certain conditions chloro-, bromo-, and lodo-complcxcs of cadmium showed multispots Wc have occasionally obbcived these multispotsalsom the cicctrophorcsis of other metal complcKCb