bluuebunny/crossref_metadata_2025_split huggingface dataset:
Phospholipase B Activity of Purified Phospholipases A from Vipera Palestinae and Naja Naja Snake Venoms
Authors: Shiloah Joseph 
Published: November 2013

AbstractPhospholipase was isolated from Vipera palestinae (in two fractions) and from Naja naja (in six fractions) snake venoms. The enzymes were shown to possess phospholipase A activity (hydrolyzing diacyl‐sn‐glycerophosphorylcholine e.g., lecithin, in the 2‐position) as well as lysophospholipase (phospholipase B) activity (hydrolyzing 1‐monoacyl‐sn‐glycerophosphorylcholines, e.g., lysolecithin, yielding free fatty acid and glycerophosphorylcholine). All the phospholipase preparations obtained were shown to be pure by immunological criteria. The V. palestinae phospholipases also gave one band each on acrylamide gel electrophoresis. The ratio of the specific activity at various purification stages of each venom, to the specific activity of the whole venom, was the same for A activity (substrate lecithin) as for B activity (substrate lysolecithin). The A activity had a pH optimum at 9; B activity was low at this pH but increased steadily beyond pH 10.5.
The Ordered Polymer (Pro‐Gly‐Pro)n an Immunological Model for Collagen
Authors: Fuchs Sara , Maoz Arieh , Sela Michael 
Published: November 2013

AbstractThe periodic collagen‐like polytripeptide (Pro‐Gly‐Pro)n is immunogenic in several species of animals. Antibodies to this polymer are specific to the unique collagen‐like conformation of the immunogen. There is an immunological cross‐reactivity between (Pro‐Gly‐Pro)n and natural collagens in several systems, and it is possible to induce an autoimmune response to collagen by means of the synthetic polymer. The ordered polymer (Pro‐Gly‐Pro)n as well as collagen are thymus‐independent antigens, whereas the random polymer (Pro66, Gly34)n and gelatin are thymus dependent.
Natural Toxins as Tools in Neurophysiology
Authors: Brown George , Witkop Bernhard 
Published: November 2013

AbstractSnake venoms (bungarotoxin, cobratoxin), frog poisons (histrionicotoxin, batrachotoxin and atelopidtoxin), and fish toxins (tetrodotoxin, saxitoxin) permit selective inhibition of receptors and ion transport mechanisms in electrogenic membranes. Selective ion binding mechanisms are exemplified by the sodium and lithium complexes of antamanide, the naturally occurring cyclic decapeptide from the mushroom Amanita phalloides.
Some Properties of Methyl Diphenyl Phosphate
Authors: Apelblat Alexander , Sahar Ayala 
Published: November 2013

AbstractThe physicochemical properties of methyl diphenyl phosphate (MDPP), alone or in binary and tertiary systems which include water, are presented. The data included are: melting point, boiling point, viscosity, surface tension, dipole moment, IR and UV spectra of MDPP, mutual solubilities of MDPP and water, viscosities, and solubilities of MDPP in several aqueous chlorides.
Scope of the Friedel‐Crafts Synthesis and 1H NMR of Phenoxaphosphinic Acids
Authors: Levy J. B. 
Published: November 2013

AbstractA meta‐methyl substituent on diphenyl ether blocks attack ortho to it in the reaction with phosphorus trichloride and aluminum chloride, allowing the synthesis in acceptable yield of the phenoxaphosphinic acids II–VI. The NMR of the aromatic hydrogens reveals a long‐range coupling of 8 Hz between phosphorus and hydrogens at the 4‐ and 6‐positions. Revised rules for predicting methyl chemical shifts of phenoxaphosphinic acids are given.
Transient and Energy Transfer Studies of Bianthrone and Related Compounds in Fluid and Rigid Media
Authors: Richtol H. H. , Strong R. L. , Dombrowski L. J. 
Published: November 2013

AbstractThe photochromic modification of bianthrone can be produced through a triplet excited state at room temperature in fluid media, as shown by biacetyl photosensitization and phosphorescence quenching. A triplet state of these compounds is observed at 77 K in a methanol ethanol glass, but it is not established if this is the photochromic precursor.
Stability and Thermodynamics of Glutamic Acid Complexes with Cerium(III) and Yttrium(III)
Authors: Sekhon B. S. , Chopra S. L. 
Published: November 2013

AbstractStepwise stability constants of the complexes of glutamic acid with cerium(III) and yttrium (III) have been determined by the Calvin‐Bjerrum pH titration technique as used by Irving and Rossotti in aqueous solution at 25° and 45°C. The values of log β2 for cerium complexes are: 9.75 (μ = 0.1), 9.57 (μ = 0.2), 9.38 (μ = 0.3) at 25°C; and 10.90 (μ = 0.1), 10.74 (μ = 0.2), 10.64 (μ = 0.3) at 45°C. The log β2 values for yttrium complexes at μ = 0.1 are 9.98 and 9.77 at 25° and 45°C respectively. The values of log β2 (μ = 0.0) for cerium complexes are 10.21 and 11.24 at 25° and 45°C respectively. The increasing ionic strength of the medium decreases the stabilities of cerium complexes which are also more stable at 45° than 25°C whereas yttrium complexes are less stable at 45°C. The values of AH and ΔS are positive for cerium complexes whereas in the case of yttrium complexes, the values of ΔH are negative and those of ΔS are positive.
Some New Organoantimony(V) Compounds
Authors: Chang Ming‐May Y. , Su Kai , Musher Jeremy I. 
Published: November 2013

AbstractA series of antimony(V) compounds containing bifunctional ligands has been prepared. These compounds are of the structure (C6H5)3 Sb (OOCR)2 and (R = P − C6H4OH5 o‐C6X4COOMe and cis‐CX=CX where X = H, Cl and Br). These are the first antimony(V) compounds which contain functional reactive end groups.
On the Polarographic Reduction of Griseofulvin and Some of its Derivatives
Authors: Unterman H. W. , Duca Al. 
Published: November 2013

AbstractThe mechanism of the polarographic reduction of griseofulvin was elucidated. The first wave is due to the 4′‐carbonyl group reduction, and the second to the C′2‐C′3 ethylenic linkage reduction. Substitution into the 2′‐ and 3′‐positions of griseofulvin or isogriseofulvin C ring, shifts appreciably the half‐wave potential values.
Photochlorination of Stearic Acid Adsorbed on Alumina
Authors: Eden Ch. , Shaked Z. 
Published: November 2013

AbstractStearic acid adsorbed on alumina as a dense monomolecular layer was photochlorinated in the dry solid state. The results show that over 90% of the chlorination was on the ω and ω‐1 positions and 8.5% on ω‐2. No chlorination was detected on the other positions. This establishes the assumption that in a dense monomolecular layer only the terminal groups are exposed to chemical reaction.
Integrals Over Two‐Centre Orbitals
Authors: McEachran R. P. , Cohen M. 
Published: November 2013

AbstractWe present analytic recursion formulae sufficient to generate electron repulsion integrals calculated with σ‐type two‐centre basis functions. A simple calculation of the ground state energy of the hydrogen molecule, using some of the integrals generated by this method, yields total energies in fair agreement with more accurate values.
Synthesis in Jasmone Series. IV. Preparation of Methyl‐2‐Oxo‐5‐Pentylcyclopentyl‐1‐Acetate and its 4‐Pentyl Analogue
Authors: Ravid Uzi , Hoffer Dorith , Ikan Raphael 
Published: November 2013

AbstractTwo new analogues of methyldihydrojasmonate (14); methyl‐2‐oxo‐5‐pentylcyclopentyl‐1‐acetate (5) and methyl‐2‐oxo‐4‐pentylcyclopentyl‐1‐acetate (12) were synthesized. The key step in these syntheses was 1,4‐addition of trialkylborane to α, β‐unsaturated cyclopentenones, 4 and 9.
The Solubility of Fine Particles and the Supersaturated Solution
Authors: Glasner Abraham 
Published: November 2013

AbstractSupersaturated solutions equilibrated with fine particles remain stable, when thermostated for long periods, i.e., “Ostwald ripening” is rather slow. It is argued that this is because the “excess” solute is contained in the supersaturated solution in the form of bloc nuclei the size of which are nearly as large as that of the fine particles in suspension. In the case of real supersaturated solutions, which invariably contain impurities serving as heterogeneous nucleating agents, also, a quasi equilibrium of bloc nuclei of a narrow size‐distribution is established. This is a logical consequence of the kinetic theory of embryal growth owing to local fluctuations. The heat released by the growing embryos (or bloc nuclei) at any moment is proportional to their increase in surface area.
Super Acid Catalyzed Bromination of Isoalkanes
Authors: Halpern Y. 
Published: November 2013

AbstractIsoalkanes are brominated by Br2 in liquid SO2 in the presence of catalytic amounts of super acids (SbF3 or SbF5 – HSO3F (1:1 molar ratio – “Magic Acid”)) to yield mono, di and tri bromoalkanes. A possible mechanism is discussed.
Thermal and Photochemical Decomposition of Dihydrooxadiazinones
Authors: Fuchs B. , Kwalwasser W. D. , Rosenblum M. 
Published: November 2013

Abstract3,6‐Dihydro‐1,3,4‐oxadiazin‐2‐ones may be prepared from either α‐ketols or from α‐diketones and carbethoxyhydrazine. These substances undergo thermal or photolytic (253.7 nm) decomposition to give N2, CO2 and olefins. Oxadiazinones derived from medium ring α‐ketols give bicyclic hydrocarbons in addition to olefins. These are shown to be formed by decomposition of the intermediate vinyldiazene to vinyl radicals, followed by transannular hydrogen abstraction and alkyl radical addition to the olefin. A series of 5,6‐dihydro‐1,3,4‐oxadiazin‐2‐ones have also been prepared and their thermal and photolytic behavior studied.
Boron Phosphate in Heat‐Absorbing Soda‐Lime Glass
Authors: Ashboren David , Herling David 
Published: November 2013

AbstractThe present qualitative study evaluates the possibility of employing boron phosphate as a component of heat‐resisting glasses based on the lime‐soda composition. In the presence of ferrous oxide, boron phosphate decreases the former's heat‐resisting capacity. The heat‐resistance of nickel oxide was markedly enhanced by boron phosphate. In this case, little distortion of the visible spectrum was noted. Measurements were mainly spectrophotometric, with some in direct sunlight.
Experimental Investigation of the Thermal Dependence of the Piezo‐Optical Coefficient of Water between 5 and 90°C
Authors: Shraiber L. S. 
Published: November 2013

AbstractResults are presented of an experimental study of the piezo‐optic effect of water over a wide temperature range, 5–90°C, at four spectral lines. We show that unlike other liquids, the temperature dependence of the piezo‐optic coefficient (Δn/ΔP)T of water passes through a minimum in the vicinity of 40–60°C. A qualitative explanation of the anomalies found is given, by use of contemporary theories of water structure.
The Effect of Polyamines on the Photochemical Reactivity of DNA
Authors: Ben‐Hur E. 
Published: November 2013

AbstractThe effects of diaminopentane (cadaverine), diaminoethane and the polyamine, spermine, on the photoreactions of 4,5′, 8‐trimethylpsoralen with DNA were studied. Near ultraviolet (UV) light (360 nm) irradiation of psoralen with DNA results in the formation of psoralen monoadducts with pyrimidine bases and DNA interstrand crosslinks. The polyamines studied reduced the rate of both photoreactions to the same extent by a factor of 1.5–2.0. The magnitude of the effect increased with polyamine concentration. Effectiveness was in the order spermine > cadaverine > diaminoethane. This is also the same order for stabilization of the DNA double‐helix. Under conditions of higher DNA stability (higher ionic strength), higher polyamine concentrations were required to obtain an effect which was smaller than at low ionic strength. It is concluded that the photoreactions of psoralen with pyrimidines in DNA require some distortion of the double‐helix. This distortion is made more difficult in the presence of stabilizing agents like polyamines and therefore the rate of the reaction is reduced. If crosslinking of DNA by psoralen is a two‐step reaction then it must be concluded that the second step does not require further distortion. Consistently with the above, polyamines also reduced the UV‐induced dimerization of thymine in DNA, although to a lesser extent.
The Kinetics of the Reaction Between Copper (II)‐Ions and Tropaeolin O
Authors: Perlmutter‐Hayman Berta , Shinar Ruth 
Published: November 2013

AbstractThe system Cu(II)‐ions‐tropaeolin O has been investigated at 25°C. Spectrophotometric measurements indicate that a 1:2 complex is formed in which one of the originally internally bonded hydrogens is retained. The kinetic results, obtained by the temperature‐jump technique, essentially confirm this suggestion.
Structural Organic Thinking and Computer Assistance in Synthesis and Correlation
Authors: Dubois Jacques‐Emile 
Published: November 2013

AbstractComputer assistance in synthesis, in modern analytical identification, in correlation and documentation can be carried out either through adaptation programs which tend to be rather clumsy for current chemical presentation or through a reorganization of the latter. Current organization which, in its dual description of the “whole and the parts”, favours the parts (sub‐structures), is thus essentially based on fragmentation. To this pragmatic approach can be opposed another which consists of enhancing global description by means of a carefully chosen metalanguage with a rich syntax. A major advantage of such a global structural approach lies in its ability to produce, by programming, different specific sets of sub‐structures, including those found in current chemical presentation. The DARC system carries out this type of unitary organization by a generation law which builds structures (S) and organized populations or hyperstructures (HS). The topochromatic generation of a chemical corpus enables the latter to be fragmented and partitioned ad infinitum at will. Assisted classical and non‐classical fragmentation, the creation of external environments of structures, the exhaustive enumeration of structures and reaction pathways will be illustrated by examples drawn from our work in structural correlations and synthesis.
Construction and Use of Central Force Models for the Theory of Polyatomic Fluids
Authors: Stillinger Frank H. 
Published: November 2013

AbstractIn order to avoid technical problems posed by nonspherical interactions in the statistical mechanics of liquids, central force models can be devised to describe polyatomic substances. In this approach separate spherical potentials exist for each type of atomic pair. In the case of water, three functions are necessary: VOO(r), VHH(r), and VOH(r); they can be selected so that proper molecules spontaneously form and engage in linear hydrogen bonds. In addition to conventional properties, central force models permit study of molecular vibration and dissociation. Details for NH3, H2O, HF, and CH4 are presented.
Re‐Use and Disposal of Waste Acids
Authors: Theilig Gerhard , Müller Gerhard , Bodenbenner Kurt 
Published: November 2013

AbstractHydrochloric acid and sulfuric acid represent the main waste acid by‐products in chemical manufacture. Neutralisation and conversion to inert solids as methods of disposal are of limited applicability. A number of appropriate methods have been developed for acid recycling. Hydrogen chloride (as a major by‐product of organic chlorination reactions) can be converted to chlorine by oxidation processes or by electrolysis of muriatic acid. Hydrogen chloride itself can be put to use in the synthesis of methyl chloride, vinyl chloride, chloroprene. Sulfuric acid serves as cheap solvent, reaction medium, condensation agent, drying agent, and gives rise to diluted and contaminated waste acids. Regeneration techniques (water evaporation by various methods, separation of precipitated salts, oxidation of organic impurities) lead to acids of sufficient quality to be recycled to the process of their origin. Standard grade sulfuric acid can be made from waste acids by thermal degradation to sulfur dioxide which in turn goes back to the sulfuric acid plant.
Stereoelective Polymerization Applied to Heterocyclic Compounds: A Resolution Method Giving Monomers of High Optical Purity
Authors: Sepulchre Maurice , Spassky Nicolas , Sigwalt Pierre 
Published: November 2013

AbstractStereoelective polymerizations performed on substituted oxiranes and thiiranes can yield recovered monomers of high optical purity. The efficiency of the process depends on the chemical nature, the geometry, and the configuration of the chiral ligand of the initiator. It also depends on the nature of the monomer and its enantiomeric composition. When enantiomerically enriched thiiranes were used the stereoelectivity was strongly increased and monomers which were almost optically pure could be isolated using a stepwise procedure. The resolution could be also improved by modifying the initiator with external chiral additives. This stereoelective process seems to be of special interest for the preparation of optically active monomers which are not easily obtained by conventional synthetic methods.
Stereochemistry and Circular Dichroism of Chiral Internal Olefin‐Platinum(II) Complexes
Authors: Lazzaroni Raffaello , Bertozzi Sergio , Bertucci Carlo , Salvadori Piero , Pino Piero 
Published: November 2013

AbstractA series of cis‐ and trans‐dichloro(benzylamine) (chiral olefin) platinum(II) complexes, containing (Z) and (E) isomers of the internal chiral olefins R‐CH=CH‐R', has been prepared by ethylene displacement from the corresponding ethylene containing complexes. The particular stereochemical features of the complexes allow one to interpret the CD on the basis of the individual contributions coming from the chiral centres already present in the free olefin and from the chiral centres formed in the complexation of the double bond. Evidence is reported showing that the aforementioned contributions are additive and that the chiral centre(s) bound to the metal dominates the CD at about 400 nm, its chirality type being reflected in the sign and its chirality prevalence in the Δϵ value.
Chromatographic Resolution of Chiral Olefins. Specific Rotation of 3‐Methylcyclopentene and Related Compounds
Authors: Schurig V. , Gil‐Av E. 
Published: November 2013

AbstractA recently developed gas chromatographic method was used to determine quantitatively the enantiomeric composition as well as the amounts of accompanying impurities of an olefin, thus allowing calculation of its specific rotation. Applying this procedure it was found that the specific rotation of (+)‐3‐methylcyclopentene is more than double that reported in the literature, namely [α]D20 = + 174.5° ±4.5.
Structure of Nitrosyltris(triphenylphosphine)rhodium, Rh(NO)(P(C6H5)3)3
Authors: Kaduk James A. , Ibers James A. 
Published: November 2013

AbstractThe structure of nitrosyltris(triphenylphosphine)rhodium, Rh(NO)‐(P(C6H5)3)3, has been determined from three‐dimensional X‐ray data. The compound crystallizes in the space group P3 of the trigonal system with three molecules in a unit cell of dimensions a = 19.057(4) and c = 10.799(2)Å. Least‐squares refinement of the 162 variables has led to a value of the conventional R index (on F) of 0.052 for the 5456 independent reflections having F2o > 3 σ (F2o). There are three independent molecules in the unit cell, one‐third of each being unique. The best first approximation is to describe the complex as a tetrahedral Rh( ‐I) complex; average parameters: Rh—P = 2.350(3), Rh—N = 1.759(13), N—O = 1.27(2) Å, P—Rh—P = 102.2(6), N—Rh—P = 116.0(5), Rh—N—O = 156.7(26)°. The nitrosyl groups are disordered about the threefold axes. The structure is compared with other metal nitrosyl phosphine complexes and the metal‐nitrosyl bonding is discussed.
The Crystal and Molecular Structures of Dimethylgold Methanido‐ and Nitrido‐Bis(Dimethylphosphoniummethylide): A Comparative Study
Authors: Krüger C. , Sekutowski J. C. , Goddard R. , Füller H. J. , Gasser O. , Schmidbaur H. 
Published: November 2013

AbstractThe crystal and molecular structures of the two title compounds have been determined. The two isoelectronic species are almost isostructural, with only small deviations in bond angles, distances and planarity of the ring systems. The results are compared with those of analogous nickel(II) and gallium(III) complexes, where both square planar and tetrahedral ligand arrangements are present, respectively. The typical ligand properties of the new double ylide chelates can thus be derived.
Stereospecific Syntheses of Isomeric [Mn(CO)6‐n(CNMe)n]+ Complexes and Study of their Electrochemical Oxidations
Authors: Treichel P. M. , Mueh H. J. , Bursten B. E. 
Published: November 2013

AbstractThe reactions of Mn(CO)5‐n(CNMe)nBr (n = 2, 3, 4) with either CO or CNMe in the presence of a halide acceptor are found to be stereospecific, with incoming ligand replacing the halide ion. These reactions were used in the syntheses of mer‐ and fac‐[Mn(CO)3(CNMe)3]PF6 and cis‐ and trans‐[Mn(CO)2(CNMe)4]PF6. A cyclic voltammetric study showed that the isomeric complexes had different E1/2 values. The difference in eases of oxidation was rationalized qualitatively based on the abilities of CO and CNMe to serve as π acceptors. This suggestion was supported quantitatively by theoretical calculations which defined the degree of stabilization of the HOMO levels in these complexes through π bonding.
Aromatic Substitution of Olefins. Reactions of 1‐Octene and Phenyl‐Substituted Butadienes with Benzene or Toluene, and the Inter‐ and Intramolecular Substitutions of Triphenylethylene in the Presence of Palladium(II) Salts
Authors: Fujiwara Y. , Asano R. , Teranishi S. 
Published: November 2013

AbstractThe reactivities of 1‐octene, 1‐phenyl‐1,3‐butadiene and 1,4‐di‐phenyl‐1,3‐butadiene toward benzene or toluene in the presence of palladium salts were examined. 1‐octene and benzene gave trans‐1‐phenyl‐1‐octene (1) as a major product with its cis‐isomer (2), 2‐phenyl‐1‐octene (3) and 2‐phenyl‐2‐octene (4). 1‐phenyl‐1,3‐butadiene and 1,4‐diphenyl‐1,3‐butadiene react with benzene to give phenyl‐substituted butadienes predominantly. The inter‐ and intramolecular aromatic sub‐situations of triphenylethylene occurred to give p‐β,β‐diphenylvinyl‐tetraphenylethylene (9) and 9‐phenylphenanthrene (10) when treated without aromatic compounds.
Novel Decomposition Modes of Transition Metal Metallocycles Containing the Silicon–Silicon Bond: 1‐Nickela‐ and 1‐Platina‐3,4‐Disilacyclopentane Ring Systems
Authors: Tamao Kohei , Yoshida Jun‐Ichi , Okazaki Satoshi , Kumada Makoto 
Published: November 2013

AbstractReaction of 1,2‐bis(bromomethyl)tetramethyldisilane with magnesium in ether gave 1,1,3,3‐tetramethyl‐1,3‐disilacyclobutane (3) (∼ 20%) together with ca. 60% yield of the di‐Grignard reagent (5). Treatment of 5 with [Ni(PPh3)2Cl2] (7) in refluxing ether formed 3 in ca. 20% yield. Decomposition of 1‐nickela‐3,4‐disilacyclopentane intermediate, prepared from 7 with 5 at low temperatures, in the presence of 1‐naphthyl bromide, triphenylphosphine or 2,3‐dimethyl‐1,3‐butadiene also formed 3 in 12–20% yields. Reaction of 5 with Pt(COD)Cl2 (COD = 1,5‐cyclooctadiene) gave a 1‐platina‐3,4‐disilacyclopentane derivative as stable crystals, which gave 3 in quantitative yield when heated with PPh3 in benzene. Mechanisms for the formation of 3 have been discussed.
Correlation of Emotional Stress and Physical Exertions with Urinary Metabolite Profiles
Authors: Ludwig Helga , Spiteller Michael , Egger Hermann Josef , Spiteller Gerhard 
Published: November 2013

AbstractChanges in human metabolism caused by physical or mental stress were examined by monitoring the rate of excretion of metabolites via the urine. Gas liquid chromatography and mass spectra analysis of urine revealed differences in the rate of metabolite excretion between mental stressed and unstressed persons: Emotional stress causes an increase in the DHEA excretion for a factor up to twenty. Physical stress does not change the steroid pattern, but is manifested in respect to a much greater increase in excretion of citric acid and isocitric acid and decrease in excretion of amino acid conjugates in untrained persons as compared to trained athletes.