bluuebunny/crossref_metadata_2025_split huggingface dataset:
Solvent Extraction from Molten Salts I. Mercury (II) Chloride, Bromide and Iodide
Authors: Zangen M. , Marcus Y. 
Published: November 2013

AbstractThe distribution ratio D of HgCl2, HgBr2 and HgI2 between a polyphenyl phase (37 mole % biphenyl, 48% o‐terphenyl and 15% m‐terphenyl) and a mixture of molten LiNO3 and KNO3 was determined radiometrically. Log D was found to increase linearly with 1/T in the range 150–200° and values of ΔH° in this range were derived. Variation of the mole ratio K/Li in the melt between 1.00 and 1.86 (eutectic ratio = 1.33) was shown to cause considerable variations in D. The decrease of D on addition of potassium halide to the melt was found consistent with the formation of inextractable anionic complexes (HgX3− and HgX4) formation constants for these complexes are given.
Structural Evidence for Bent Orbitals
Authors: Hirshfeld F. L. 
Published: November 2013

AbstractIn a non‐linear molecule RXR′ steric repulsion between R and R′ frequently causes the bond angle at X to be larger than the angle between the orbitals of this atom that participate in the XR and XR′ bonds. These bonds are then bent. Thus the atomic orbital on R does not point directly towards atom X but is inclined at some angle to the bond axis. If R is a polyatomic group having an axis of symmetry, this axis will be similarly inclined to the R‐X bond. This effect accounts for structural anomalies that have been observed in compounds such as dimethyl ether (X = O, R = R′ = CH3) formaldoxime (X = N, R = CH2, R′ = OH) and many others.
The Reactivity of Atomic Hydrogen with Cysteine, Cystine, Tryptophan and Tyrosine in Aqueous Solution
Authors: Navon G. , Stein G. 
Published: November 2013

AbstractThe reactions of cystine, cysteine, tryptophane and tyrosine in aqueous solution with atomic hydrogen, produced in an electrodeless high frequency discharge, were studied. The specific rate constants for the velocity of the reaction of the substrates with H atoms were found to be ks = 1.5 × 109; 1.0 × 109; 2 × 109 and ∼4 × 1081·mole−1·sec−1 for cystine, cysteine, tryptophan and tyrosine respectively.
The Autoxidation of 1,1‐Dibromo‐2,2‐Difluoroethylene and Tribromoethylene. Preparation of Dibromofluoro‐ and Fluorodibromo‐Acetic Acid
Authors: Cohn H. , Bergmann Ernst D. 
Published: November 2013

AbstractThe autoxidation of 1,1‐dibromo‐2,2‐difluoroethylene gives a mixture of dibromofluoroacetyl fluoride and bromodifluoroacetylbromide, which could be separated in the form of their ethyl esters. Several reactions of the two acids have been investigated. The mechanism of the autoxidation process is discussed briefly. The preparation of dibromoacetyl bromide by autoxidation of tribromoethylene has been improved.
The Microheterometric Determination of Lead with Thionalide
Authors: Bobtelsky M. , Gancz M. 
Published: November 2013

AbstractA heterometric study was made of the reaction between lead and thionalide. A method is presented for the determination of 1 mg Pb in 20 ml aqueous solution in which Mn, Fe, Co, Ni, Cr, Mg, Zn, Al, Cu, Cd, Ag and Hg may be present. The determination takes 10–14 minutes.In the presence of large excesses of Ca, Al, Mg, and Fe, a preliminary rapid separation is necessary. The error is about 1.5%.
The Synthesis of 1‐.2‐,3‐ and 4‐Chloroanthrone
Authors: Bergmann E. D. , Blum J. , Kariv Esther 
Published: November 2013

AbstractThe reduction of 1‐ and 2‐chloroanthraquinone by various agents has been studied. For the identification of the expected halogenated anthrones, 1‐, 2‐, 3‐ and 4‐chloroanthrone have been prepared by unambiguous routes, mostly based on the reaction between a phthalic anhydride and an arylmagnesium halide.
Studies on the Purification of Kcl.: II. Spectrophotometric Determination of Magnesium and Aluminium in A. R. Alkali Halides
Authors: Glasner A. , Skurnik Sarah 
Published: November 2013

AbstractMethods for the determination of magnesium and aluminium, present as impurities, in A.R. alkali halides have been developed. Both ions were separated by co‐precipitation in the form of their hydroxides, and improved spectrophotometric methods were used for their quantitative analysis.These and other methods have been used to follow the purification of KCl by re‐crystallization from aqueous solutions, and some illustrative observations are reported.
Syntheses of Graft Polymers of Polypeptides on Polyhydroxy Polymers
Authors: Avny Y. , Zilkha A. 
Published: November 2013

AbstractGraft polymers of definite structure of poly α‐ and β‐ amino acids on natural and synthetic polyhydroxy polymers were prepared by reaction of their polymeric alkoxide derivative with N‐carboxy anhydrides (NCA) of amino acids. Five different types of graft polymers were prepared having different structures and compositions of the polypeptide side chains. Graft polymers of polypeptides on cellulose were synthesised by reaction of NCAs with cellulose xanthate in solution. The reaction of alkali metal naphthalenes with a polyhydroxy polymer, including cellulose acetate and nitro cellulose, in a suitable solvent was used for the preparation of alkoxide derivatives which served for subsequent graft polymerization. The graft polymers were obtained in high yields. In most cases no homopolypeptide was formed, and the polyhydroxy polymer backbone reacted in 70–100% yield. The formation of graft polymers was in accordance with a direct addition of the polymeric alkoxide initiator to the NCA.
Structural Factors in Respiratory Stimulation by Na+‐ions in Escherichia Coli
Authors: Kahana Luna , Avi‐Dor Y. 
Published: November 2013

AbstractWhile K+ has a general stimulatory effect on respiration in Escherichia coli, Na+ specifically enhances the rate of glutamate oxidation. Na+ reduces the apparent Km of the glutamate‐oxidase system with respect to the substrate 90 times, but has no influence on Vm. It is only effective when the cell structure remains intact, glutamate concentration is relatively low and hypotonic conditions prevail. In a cell‐free system the kinetic constants are not affected by Na+. Some implications of the above findings are discussed.
Electronmicroscopy of Permselective Membranes
Authors: de Körösy F. , Zeigerson E. 
Published: November 2013

AbstractAqueous regions within cationic permselective membranes were filled by cathodically deposited silver and sections made of this material were observed in the electron microscope. The silver itself deformed the matrix and crystallized in large globules, but the background of the micrographs, the Ag form of the membrane, showed characteristic structural elements. Anionic membranes repeatedly impregnated with telluride ions and oxydized by air also contained granular tellurium metal, which evaporated during exposure to fast electrons in the electron microscope. Using only the sulphonium groups of the membranes or heavy counter ions as electron absorbing material, we examined the structure of some membranes. Those made of polyethylene reveal a series of black and white lines, often arranged in black‐white‐black triplets, which probably are cross sections of crystalline platelets of polyethylene, reacted on their surface. Those made of PVC reveal large areas which underwent substitution to a lesser extent, surrounded by more strongly reacted coherent material. Other membranes also show characteristic elements in their microstructure.
Ion Exchange Membranes Saturated with Hydrophobic Solvents
Authors: Ilani A. 
Published: November 2013

AbstractFilters made of cellulose acetate and nitrate were saturated with toluene or bromobenzene and interposed between aqueous solutions. The membranes thus formed behaved like cation exchange membranes with the same capacity for both solvents. K ‐ Na bi‐ionic potential, its dependence on temperature, K ‐ Na selectivity and mobility ratio were similar in membranes saturated with the above solvents. However the absolute magnitude of the diffusibility was some 30 times lower in toluene saturated membranes. Activation energy of membrane conductance was higher by about 3800 cal/mole in the toluene saturated membrane. Electroosmotic phenomena in the membranes were negligible or nil. It is suggested that these membranes represent a prototype of ion exchange membranes, where the fixed charges with their counterions and hydration shell are embedded in hydrophobic medium.
Anodic Stripping Voltammetry with Superimposed A.C. Potential
Authors: Eisner U. , Yarnitzky C. , Nemirowsky Y. , Ariel M. 
Published: November 2013

AbstractThe combination of a. c. polarography with linear scan anodic stripping voltammetry has been investigated, employing a self‐constructed, phase discriminating a. c. attachment. The resolution and sensitivity of the method was compared with those obtainable, under similar experimental conditions, by plain anodic stripping voltammetry. Changes in the concentration of the supporting electrolyte and the presence of dissolved oxygen frequently affect the sensitivity and must be carefully controlled. The practical application of the method is illustrated by applying it to the determination of zinc in solutions and in a standard silicate sample.
Reactivators of Inhibited Acetylcholinesterase. II. The Preparation and Properties of Some New 4‐Hydroximinomethyl‐1‐(N‐Aminoalkyl)‐Pyridinium Salts
Authors: Ashani Y. , Cohen Sasson 
Published: November 2013

AbstractA new series of heterocyclic oximes, prepared by the quarternization of 4‐hydroximino‐methylpyridine with various aminoalkyl halides, have been tested as reactivators of phosphorylated cholinesterase. With the most active member, 4‐hydroximinomethyl‐l‐[3(N, N‐dimethylamino)‐n‐propyl]‐pyridinium chloride, the rate of reactivation is comparable to that obtained with the known diquarternary compound, TMB‐4. These findings shed new light on the mechanistic concept of the reactivation process.
Hydrogen Isotope Effects in the Radiolysis of Water
Authors: Vukmirovié Zorka B. 
Published: November 2013

AbstractThe tritium fractionation between water and radicals formed in the radiolysis of dilute solutions of monomerous methyl methacrylate in H2O‐HTO and D2O‐DTO mixutres was studied. A parallel determination of the tritium content in molecular hydrogen was performed. Also, the isotopic composition of the initial molecular hydrogen was measured in the concentration range 10 to 90 Mol% D2O of H2O‐HDO‐D2O mixtures.Hydrogen atoms, hydroxyl radicals and molecular hydrogen produced in the radiolysis of these solvents were found to be depleted in heavier hydrogen isotopes. The isotope effects on the composition of hydrogen atoms are discussed in terms of the rate isotope effects in proton transfer. The isotope effects on the composition of hydroxyl radicals are close to those on molecular hydrogen and their extent suggests ionic dissociation of water as a rate‐determining step in the process of formation of both products.
1‐Phenylcycloakylamine Derivatives I
Authors: Kalir A. , Pelah Z. 
Published: November 2013

Abstract1‐Phenyl substituted cyclobutyl‐, cyclopentyl‐, and cyclohexylamines were obtained in the Hofmann reaction of 1‐phenylcycloalkanecarboxamides. 1‐Phenylcyclohexylamine was also prepared by the Ritter reaction of 1‐phenylcyclohexanol.
Radiolysis of Fremy's Salt in the Presence of Some Hydrated Electron Scavengers in Alkaline Aqueous Solution
Authors: Mantaka Anastasia , Rakintzis N. 
Published: November 2013

AbstractFremy's salt, ON(SO3)22−, was irradiated with γ‐rays in deaerated alkaline aqueous solutions in the presence of NO3−, N2O. In the presence of N2O an increase of the G(‐ON(SO3)22− = G from 6.1 to about 6.7 was observed within a limited range of concentration, while with NO3− the change is gradual. This is consistent with NO2 and OH produced, respectively, in the reaction of eaq− with Fremy's salt, taking place in one‐electron‐equivalent processes, and with the assumption that pairs of radicals may originate from water molecules.
The Preparation and Properties of Some Covalently Bonded Purine‐Pyrimidine Base Pairs
Authors: Lachman Ch. , Cohen S. 
Published: November 2013

AbstractCovalently bonded purine‐pyrimidine base pairs have been prepared by the reaction of 6‐trichloromethylpurine with various 5‐aminopyrimidines. The most probable structure of the new compounds is discussed in the light of their physical constants.
Movement of Salt in Saturated Soil Columns
Authors: Mokady R. S. , Ravina Israela , Zaslavsky D. 
Published: November 2013

AbstractCalcium chloride solutions were passed through a saturated non‐expanding calcium clay soil. The breakthrough curves were found to depend on the CaCl2 concentrations and on the rate of flow. The results are explained by ion exclusion and hydrodynamic dispersion mechanisms.
Hydrogen Consumption and Silica Release During Initial Stages of Phosphate Adsorption on Kaolinite at a Constant pH
Authors: Kafkafi U. 
Published: November 2013

AbstractThe release of silica from kaolinite is enhanced immediately after application of phosphate. The rate of the silica release was inferred from the rate of hydrogen additions needed to keep the system at a constant pH. Potassium increases silica hydrolysis from kaolinite surfaces in 1N solution more than calcium or sodium.
Non‐Uniform Distribution of Phosphorus Fertilizer its Significance in Dry Matter Yield Production and Phosphorus Uptake
Authors: Giskin M. , Hagin J. 
Published: November 2013

AbstractA greenhouse study was initiated to test whether plant yield and phosphorus uptake are governed by localized phosphate concentrations or by an average value of the phosphate present in the total volume of the container. The experimental design gave three fertilizer concentrations per unit fertilized soil, when disregarding concentrations; five levels of phosphate were applied to the whole pot. For all forms of phosphates used the results showed a clear dependence of yield and percentage P in dry matter on the total supply of phosphates in the root zone and not on local concentrations obtained when assembling the fertilizer in a relatively narrow zone of the container.
An Apparatus for Simultaneous DTA and TGA
Authors: Patai S. , Halpern Y. , Esterman L. , Weinstein M. 
Published: November 2013

AbstractAn apparatus based on a Cahn Electrobalance was built in order to study simultaneously, and on the same sample, decomposition reactions by differential thermal analysis and thermogravimetric analysis. The apparatus is comparatively inexpensive and enables reactions to be studied in vacuo, or in any chosen atmosphere. Samples of 20 – 25 mg, both inorganic (for example copper sulfate pentahydrate and calcium oxalate monohydrate) and organic (for example cellulose), give satisfactory results.
Cytokinins: Synthesis and Biological Activity of Related Derivatives of 2iP, 3iP, and their Ribosides
Authors: Leonard N. J. , Hecht S. M. , Skoog F. , Schmitz Ruth Y. 
Published: November 2013

AbstractChemical conversions of 6‐(3‐methyl‐2‐butenylamino)purine, 2iP, and 6‐(3‐methyl‐3‐butenylamino)purine, 3iP, to common products have been effected. A number of compounds related to these isomers and their ribosides have been synthesized, including 6‐(3‐hydroxy‐3‐methylbutylamino)‐9‐β‐D‐ribofuranosylpurine, 6‐(3‐chloro‐3‐methylbutylamino)purine, 6‐(3, 4‐dihydroxy‐3‐methylbutylamino) purine, and 6‐(3,4‐dihydroxy‐3‐methylbutylamino)‐9‐β‐D‐ribofuranosylpurine, and the cytokinin activities have been compared in the tobacco bioassay. The effect of 4‐hydroxyl substitution on the side chain has been noted. Diagnostic fragmentations of the side chains have been observed in the mass spectra.
The Chemistry of Cyclic Hydrazides. IX. The Synthesis and Alkylation of 1,2‐Disubstituted‐Perhydropyridazine‐3,6‐Diones
Authors: Feuer H. , Rosenquist E. P. , Brown F. 
Published: November 2013

AbstractThe synthesis of 1,2‐disubstituted perhydropyridazine‐3,6‐diones in high yield is described. The reaction of succinic anhydride and 1,2‐dialkylhydrazines leads to N,N′‐dialkyl‐3‐carboxypropionhydrazides which are converted to 1,2‐dialkylperhydropyridazine‐3,6‐diones in refluxing xylene or polyphosphoric acid. The reaction of 1,2‐diarylhydrazines with 3‐carbomethoxypropionyl chloride and hydrolysis of the resulting N,N′‐diaryl‐3‐carbomethoxypropionhydrazides yields N,N′‐diaryl‐3‐carboxypropionhydrazides. Cyclization of these acid‐hydrazides in thionyl chloride at low temperature affords the corresponding 1, 2‐diarylperhydropyridazine‐3,6‐diones. The alkylation of 1,2‐dipropyl‐perhydropyridazine‐3,6‐dione in various base‐solvent systems with methyl and isopropyl iodide is reported.
The Decarboxylation of α‐Arylcinnamic Acids
Authors: Klein J. , Shekhori E. 
Published: November 2013

Abstractα‐Phenylcinnamic and 2,5‐diphenylbutadienoic acids undergo decarboxylation in quinoline in the presence of copper catalysts with retention of configuration. However, both isomers of α‐(p‐nitrophenyl)‐cinnamic acids on decarboxylation in quinoline without a catalyst give a product containing mostly the cis isomer of p‐nitrostilbene. A similar course of decarboxylation was observed in dimethylformamide in the presence of a base. A mechanism based on the formation of a carbanion intermediate is assumed for the α‐nitrophenylcinnamic acids.
Effect of Medium on Transients and on Observed Quantum Yields in Photoreduction of Benzophenone by 2‐Propanol
Authors: Cohen S.G. , Cohen J.I. 
Published: November 2013

AbstractThe quantum yield for photoreduction of 0.1 M benzophenone by 2‐propanol, at 313 mμ, light intensity 1 × 1016 quanta/sec cm2 is −1.16. The quantum yield increases on dilution with benzene to 1.70 at 3.13 M 2‐propanol. A Stern‐Volmer plot of data below 3 M 2‐propanol leads to an extrapolated limiting quantum yield of ˜1.9. The quantum yield in 2‐propanol decreases with extent of conversion from 1.1 at 17% to 0.74 at 37% photoreduction. Quantum yields for photoreduction of 0.1 M benzophenone by 1 M 2‐propanol and by 1 M benzhydrol in benzene remain constant with conversion. A light absorbing transient builds up strongly and progressively during photoreduction in 2‐propanol, and to a much lesser extent in 1 M 2‐propanol and 1 M benzhydrol in benzene. Photoreduction in 1 M 2‐propanol in t‐butyl alcohol appears to behave like that in 2‐propanol; 1 M 2‐propanol in acetonitrile shows behavior intermediate between that in alcoholic and in hydrocarbon solutions. Efficiency of quenching by naphthalene in alcoholic and in hydrocarbon media indicates that kr is about twice as great in the hydrocarbon as in the alcohol solvents. The effect of the hydrocarbon in diminishing build up of the light absorbing intermediate, which may mask and possibly quench, is largely responsible for the increase in quantum yield on dilution with hydrocarbon.
Photosensitized Dimerization of Thymine and Cytosine in DNA
Authors: Ben‐Ishai R. , Ben‐Hur E. , Hornfeld Y. 
Published: November 2013

AbstractThymine and cytosine homo‐ and heterodimers ate produced when E. coli DNA is irradiated at wavelength > 300 mμ in the presence of acetone as photosensitizer. Employing acetophenone as sensitizer only thymine containing dimers are obtained. In heat denatured DNA photosensitized dimerization of thymine occurs in a higher proportion of the TT dinucleotide sequences than in native DNA and the trans‐syn thymine dimer isomer is formed as a minor photoproduct.
Ionization Efficiency Curves by the Retarding Potential Difference (RPD) Method
Authors: Grajower R. , Lifshitz Chava 
Published: November 2013

AbstractIonization efficiency curves obtained by the RPD (retarding potential difference) method are presented for Cycl. C4F8−, Hg+, C2 H2+ and C2 F4+. The C4 F8− resonance capture curve is given for a variety of experimental conditions. The curves for the positive ions are compared with similar curves obtained previously by the technique of photoionization combined with mass analysis. The results are discussed in terms of possible relaxation effects and other artefacts in the RPD method and in terms of threshold laws of ionization by electron and photon impact. Special emphasis is placed on autoionization processes. Experimental conditions, under which the RPD ion source may be reliably used, are specified.
N‐ Vs. C‐ Tricyanovinylation of Ring‐Substituted Dimethylanilines. The Spectral Properties of the Products.
Authors: Rappoport Z. , Shohamy Esther 
Published: November 2013

AbstractMethods for changing the selectivity in the N‐ vs. C‐ tricyanovinylation are discussed. In acetonitrile, 2,3‐, 2,4‐, 3,4‐ and 3, 5‐dimethylanilines are N‐tricyanovinylated, 2,6‐dimethyl‐ and 2, 6‐diethylanilines are p‐tricyanovinylated, and 2,5‐dimethyl‐ and 2‐ethylaniline give mixtures of N‐ and p‐tricyanovinyl derivatives. The UV, IR, NMR and mass spectra of the products are discussed in relation to the position of the tricyanovinyl group and to electronic and steric effects.
Reactions of Cyclopropane Derivatives with Nitrogen Compounds, I. The Synthesis of Pyrrolidines by the Leuckart Reaction of Cyclopropyl Ketones
Authors: Breuer E. , Stein Yona 
Published: November 2013

AbstractReactions of aryl cyclopropyl ketones with formamide, in the presence of magnesium chloride, give predominantly the corresponding 1‐formyl‐2‐arylpyrrolidines (II).
The Stretching Frequencies of Isotopic Arsenate and Permanganate Ions in Aqueous Solutions
Authors: Pinchas S. 
Published: November 2013

AbstractThe infrared absorption of crystalline powders and D2O solutions of normal and 84.5 atom % 18O‐labelled sodium arsenate as well as normal and 83.3 atom % 18O‐labelled sodium permanganate was measured in the 780–980 cm−1 region. The ν1 and ν3 fundamentals of the aqueous As18O43− ion appear at 834(sh) and 866(s) cm−1 while the respective As18O43− values are 808 and 822 cm−1 These as well as other data are shown to indicate that the water molecules which hydrate this ion are attached to its As atom. The ν3 frequency of the aqueous Mn18O4− ion is observed at 917 cm−1 and that of hydrated Mn18O4− at 878 cm−1.
Synthesis of New 6‐Selenopurines by Selenohydrolysis of 3‐Alkyl‐6‐Methylthiopurines
Authors: Bergmann F. , Rashi M. 
Published: November 2013

Abstract3‐Alkyl‐6‐methylthiopurines undergo facile selenohydrolysis to the corresponding 3‐alkyl‐6‐selenopurines. The behavior of the latter to both nucleophilic and electrophilic substitution closely parallels that of the thio analogs. The 6‐methylseleno ethers are 4–6 times more toxic to albino mice than the corresponding 6‐selenopurines.
Organometallic Studies. Part XXVII [1]. Mass Spectra of Some Monosubstituted Ferrocenes [2]
Authors: Cais M. , Lupin M. S. , Sharvit J. 
Published: November 2013

AbstractThe spectra of twelve monosubstituted ferrocenes are reported and discussed. The presence of the metal atom in many of the fragment ions observed, appears to play a role in determining the subsequent fragmentation paths of these ions. The suggested fragmentation schemes include some interesting intramolecular rearrangements, involving the metal atom.
Critique of the Mathematical Theory of Diffusion of Electroactive Species to Electrodes
Authors: Fried Ilana 
Published: November 2013

AbstractRigorous mathematical treatment of the classical theory of diffusion of an electroactive species to an electrode exposes an error in the theory. According to the corrected theory, the initial concentration (at t = 0) of the electroactive species is uniform throughout the solution except at the electrode surface. Fortunately, diffusion theory results remain unaltered. Two important conclusions result from the corrected theory: a. the plane of the “electrode surface” is inside the diffuse double layer, and b. the exact function of the concentration of the electroactive species in the double layer has no effect on the solution of the diffusion equation. These results, although intuitively accepted, are rigorously proved.