Intradiffusion coefficients in perchloric acid solutions: Water at 5°C; water and perchlorate ion at 25°C

Intradiffusion coefficients for tritiated water (³HHO) and perchlorate ion (³⁶ClO ₄ ^- ) were measured in perchloric acid solutions. At 5°C the diffusion coefficient measured for the tritiated species increases to a maximum near 1.3 mol-dm^–3. The data at 25°C have been used to calculate distinct diffusion coefficients, D _ij ^d . As a precursor for those calculations, new estimates were made of the Onsager phenomenological coefficients, l _ij . The l _ij and D _ij ^d are similar to the respective coefficients in hydrochloric acid solutions.     

Changes of intracellular ionic concentrations and membrane transport in alga Hydrodictyon reticulatum

Algal nets of Hydrodictyon reticulatum have been cultivated in double or triple labelled medium as to investigate the change of the intracellular concentration and membrane transport of chloride, sulphate, phosphate and sodium ions. The change of the intracellular concentrations of potassium and ammonium ions has been studied using atomic absorption and spectrophotometric methods, respectively. The release of different ionic species from algal cells should be always taken into account during the membrane transport studies.     

Polysaccharides from the wastes of vegetable and melon-type crops

The water-soluble polysaccharides and pectin substances from the wastes of vegetable and melon-type crops have been studied and their monosaccharide compositions have been determined. High- and low-methoxyl pectins have been isolated, and the physicochemical characteristics are given. Institute of the Chemistry of Plant Substances, Academy of Sciences of the Republic of Uzbekistan, Tashkent, fax (3712) 89 14 75. Translated from Khimiya Prirodnykh Soedinenii, No. 5, pp. 597–600, September–October, 1994.     

A novel transformation of O-methyldalbergin

O-methyldalbergin and related 4-phenylcoumarins are markedly different from ordinary coumarins in their behaviour towards alkali. They are stable in boiling alkali and on addition of mercuric oxide yield coumarilic acids. Phenyl-coumarilic acids undergo decarboxylation readily when boiled with aqueous alcoholic mercuric chloride to yield phenyl substituted coumarones.     

New synthetic and structural aspects in the chemistry of alkylaluminum fluorides. The mutual influence of hard and soft ligands and the hybridization as rigorous structural criterion

A general synthetic strategy starting from metal alkyls is reported based on the hydrogen difluoride anion as a suitable reagent for obtaining organometallic fluorides. The newly prepared compounds are [Me(4)N][(i-Bu)(2)AlF(2)] (1), [Ph(4)P][(i-Bu)(2)AlF(2)] (2), and [Ph(4)P][AlF(4)] (3), containing the tetrahedral anions [(i-Bu)(2)AlF(2)](-) and [AlF(4)](-). The actual structures are prototypes that allowed a comparison of inorganic and organometallic fluorides in the frame of the hard and soft acid and base principle, by means of ab initio calculations. A new theoretical model is designed to put in equation form the qualitative statements of the Bent rule. The model allows the rationalization of the tendencies of bond angle variation in [R(2)MX(2)] systems containing a main group metal (M), in terms of hybridization of the central atom and the reciprocal influence of hard and soft ligands.     

Complexation of nicotinamide with Ag+ ions in water-organic solvents

The effect of the water-ethanol and water-DMSO solvent composition on the stability of nicotinamide (NicNH₂) complexes with Ag⁺ ions at an ionic strength of 0.25 (NaClO₄) and a temperature of 25 ± 0.1°C is studied by potentiometric titration. An increase in the EtOH concentration in the mixed solvent is found to result in a higher stability of the nicotinamide complex with silver(I) ions; as the DMSO concentration increases, the complex becomes less stable. The results of the study are analyzed in terms of the solvation thermodynamic approach taking into account the electronic structure of the ligand and the solvation contributions of the fragments of the molecule.     

Charge location and fragmentation under electron impact. IV—the behaviour under electron impact of some N-methyl,N′-R-1,2,4-phosphadiazetidine-3-ones and related compounds

The ionization potentials of a series of N-methyl,N′-R-1,2,4-phosphadiazetidine-3-ones and related compounds have been determined. The nature of the highest occupied orbital of the molecules and the use of empirical rules to rationalize the variations in the ionization potentials are discussed. The changes in the fragmentation patterns are related to the different low ionization potential site(s) in each molecule. The occurrence of various rearrangement ions are discussed on a similar basis.     

Investigation of the state of a symmetrical tert-butyl-substituted macroheterocyclic compound in solution by PMR spectroscopy

The PMR spectra of the macroheterocyclic compound obtained by the reaction of 5-tert-butyl-1,3-diiminoisoindoline with 1,3-phenylenediamine in refluxing butyl alcohol and purified by chromatography on aluminum oxide were recorded. It is shown that the compound does not contain a unified conjugated macroring system. The dependence of the chemical shift of the protons of the endocyclic imino groups on the nature of the solvent was investigated. It is shown that the formation of compound-solvent intermolecular hydrogen bonds is complicated by steric factors.Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 1, pp. 62–64, January, 1981.     

3, 6-endoxocyclohexanes and -cyclohexenes. XXV. Some reactions of dimethyl 4,5-(1-benzyl-1, 2, 3-triazoline)-3, 6-endoxohexahydrophthalate

The anhydride and dimethyl ester of 4, 5-(1-benzyl-1, 2, 3-triazoline)-3, 6-endohexahydrophthalic acid, having a triazoline ring with an exo-cis configuration, are synthesized by reaction of benzyl azide with the furan-maleic anhydride adduct. Opening of the triazoline ring under the action of hydrochloric and acetic acids takes place with the separation of nitrogen and formation of the chloro and acetoxy derivatives, respectively, unaccompanied by a Wagner-Meerwein type of rearrangement.Part XXIV, see [1].