bluuebunny/crossref_metadata_2025 huggingface dataset:
The Role of Cations in Some Inorganic Hydrolysis Reactions
Authors: Perlmutter‐Hayman B. , Wieder H. , Wolff Michael A.
Published: November 2013

Cations which shift certain equilibria from left to right by forming a compound with one of the reaction products were investigated with respect to their kinetic role in the process. Silver ions have no influence on the rate of the hydrolysis of cyanogen iodide. Similarly, cations which form sparingly soluble carbonates do not influence the rate of hydration of carbon dioxide. On the other hand, the hydrolysis of chlorine is accelerated by Ag+ and, to a lesser extent, by Cd2+ and Fe(III). It is shown that the effect is not due simply to a bimolecular reaction between chlorine and the cation. In the case of Ag+, heterogeneous catalysis may play some role, in analogy with the solvolysis of organic halides. In the case of Cd2+, there is spectrophotometric evidence for compounds between Cl2 and HOCl on the one hand, and the cation on the other. It is suggested that these compounds interconvert more rapidly than do the parent substances. A similar mechanism may be operative in the case of Fe(III), and, possibly, also in the case of Ag+.
The Reaction of α,β‐Unsaturated Ethyl Esters with Vinylmagnesium Chloride
Authors: Watanabe Shoji , Suga Kyoichi , Fujita Tsutomu
Published: November 2013

While the reaction of linear α,β‐unsaturated ethyl esters with vinylmagnesium chloride yields vinyl ketones as the main product, the reaction of substituted α,β‐unsaturated ethyl esters yields triethylenic carbinols.
Computer Simulation of Cooperative Systems
Authors: Alexandrowicz Z.
Published: November 2013

Computer simulation of cooperative, many particle systems (eg. real gas, Ising lattice) encounters a difficulty inherent to the ensemble theory. Under given conditions, the typical configurations constitute a vanishingly small fraction of all possible particle arrangements. Moreover, near to certain phase transitions, the typical configurations abruptly acquire pronounced long range order. Hence a computer method (like Metropolis Monte‐Carlo), which is not explicitly oriented towards discovery of such extremely rare arrangements, will almost certainly become inadequate. An attempt is made to formulate quantitatively these elementary observations, with the view of deriving a unified search for methods, that will enable to simulate the emergence of long range order in random systems.
Energy Parameters in Polypeptides. VI. Conformational Energy Analysis of the N‐Acetyl N′‐Methyl Amides of the Twenty Naturally Occurring Amino Acids
Authors: Lewis Peter N. , Momany Frank A. , Scheraga Harold A.
Published: November 2013

The conformational space accessible to the N‐acetyl N′‐methyl amides of the 20 naturally occurring amino acids has been explored extensively with the aid of empirical energy functions, and many minima have been located. The statistical weights for all minima with energy ≤ 3 kcal above the lowest for each residue have been calculated. In numerous cases, the conformation of lowest energy does not possess the highest statistical weight, thereby emphasizing the importance of considering the conformational librations when comparing theoretical and experimental results. The calculated minimum‐energy conformations, as well as those of highest statistical weight, are for the most part in good agreement with experimental results from studies of these compounds in solution and in the crystalline state.
Statistical Thermodynamics of Ionic Systems
Authors: Litan Adiel
Published: November 2013

A statistical thermodynamical method is presented for calculation of thermodynamic properties of ionic systems. The method has a straightforward formalism for taking into account a variety of physical factors, e.g., making allowance for different finite volumes of different ionic species, treatment of neutral species as thermodynamic components (rather than merely regarding them as a dielectric medium), consideration of dependences of the dielectric constant on solvent composition (in the case of a mixed solvent) and on electric field strength, nonionic interactions, etc. The method is based on an approach of J. L. Jackson [1] whereby a fluctuation state of the system is characterized in terms of a set of functions for the spatial variations of concentrations of the various species. For such a state an appropriate Boltzmann factor is defined and a calculation of a thermodynamic property of the system requires integrations of this factor over function spaces. Two simple applications of the method are worked out by way of illustration and other, more refined, applications are pointed out.
Some Comments Relating to the Physical Chemistry of Polyelectrolytes
Authors: Morawetz Herbert
Published: November 2013

The possible dependence of the “unperturbed dimensions” of ionizable polymer chains on the charge density along the macromolecular chain is discussed in the light of theoretical studies and of experimental evidence. Some experiments on the behavior of dicarboxylic acids are suggested which would provide information useful in the interpretation of the behavior of polycarboxylic acids. A kinetic study of intramolecular reactions of polyions carrying small numbers of randomly spaced reactive and catalytic groups is proposed as a means to characterize chain flexibility. Finally, the advantages are pointed out which result from supplementing data on the ionization equilibrium of polymeric acids with calorimetric data.
Excluded Volume Study of Potassium Polystyrenesulfonate‐Potassium Chloride Solutions
Authors: Raziel Adrian , Eisenberg Henryk
Published: November 2013

Intrinsic viscosities [η], sedimentation coefficients s, radii of gyration Rg and second virial coefficients A2, refractive index increments and apparent specific volumes were determined in aqueous solution in theta solvents and over a wide range of concentrations ms of a supporting electrolyte KCl, for five samples of potassium polystyrene sulfonate prepared by sulfonation of narrow molecular weight distribution polystyrenes. Coil expansion coefficients α as well as the Flory coefficient Φ relating [η] to coil dimensions were evaluated. Following a theory of Alexandrowicz, α2 was found to be a linear function of M1/4 m−1/3S; Φ appears to decrease with increase in α. The low values of Φ, characteristic for polyelectrolyte solutions, are consistent with the value determined for the Mandelkern‐Flory parameter β = Φ1/3 P−1.
The Effect of Water Activity on the Dissociation of Weak Ion Exchangers
Authors: Michaeli I. , Kinrot A.
Published: November 2013

The effect of salt on the pH titration curves of weak acid or weak base ion exchangers is discussed, and conditions are formulated for the representation of such titration data by a single master curve. Inspection of experimental data both from the literature and from new measurements reported in this paper shows appreciable deviations from single master curves. These deviations are discussed in terms of the effect of salt on the activity of water. Thermodynamic considerations show that such deviations provide quantitative information on the number of water molecules taken up by the resin following the ionization of the weakly aeidic or basic groups involved. Relatively large changes in hydration are found in some systems; these are especially pronounced in systems undergoing conformational transitions.
Characterization of Charged Membranes During Hyperfiltration: The Transport Numbers
Authors: Kedem O.
Published: November 2013

A procedure for the measurement of ionic transport numbers, with the aid of current‐carrying electrodes that are introduced into a hyperfiltration cell is suggested. This procedure is suitable for adsorbed polymer layers and dynamic membranes. For membranes adequately described by the fixed charge model, allowing for ion‐association, a simple relation between transport numbers and salt rejection is derived. This leads to a test for the mechanism of salt rejection.
Phosvitin, A Phosphoglycoprotein
Authors: Perlmann Gertrude E.
Published: November 2013

Studies of viscosity, optical rotatory dispersion and circular dichroism on the phosphoglycoprotein phosvitin indicate that this protein resembles a polyelectrolyte. At alkaline pH phosvitin has an unordered conformation, whereas at pH 3.0 to 3.6 some β‐structure is present. When at pH 3.6 an organic solvent is added to a phosvitin solution the protein undergoes a transition from the random conformation to β‐structure. Similarly, if phosvitin interacts with the polybases poly‐L‐lysine and protamine the complexes form a β‐pleated sheet structure.
Fluorescence and Optical Activity of Acridine Dyes Bound to Poly‐A and DNA
Authors: Gafni A. , Schlessinger J. , Steinberg I. Z.
Published: November 2013

Complexes of acridine orange (AO) and 9‐aminoacridine (9‐AA) with poly‐A and DNA were studied by absorption and fluorescence spectroscopy, circular dichroism and circular polarization of fluorescence. The nucleotide:dye ratio (P/D) ranged from 20–2. The dye in the AO:poly‐A complex is predominantly in the dimeric form. The optical activity of the monomer dye in the excited state is very small, while that of the dimeric dye is relatively large and its dependence on wavelength and P/D indicates the presence of higher aggregates. At low P/D ratios some transfer of electronic excitation energy from dimer to monomer takes place. The spectral properties of the dye in AO:DNA complexes are different at the P/D ratios of 15 and 3, reflecting different modes of complexing. In contrast to the AO:poly‐A complexes, the optical activity of the AO:DNA complexes in the ground and in the excited states are of comparable magnitude; little change thus seems to take place in the interaction between dye and polymer upon electronic excitation of the dye in AO:DNA. In the 9‐AA:poly‐A complex the dye does not tend to dimerize when in the ground state. Excimer emission was, however, observed; dimers and higher aggregates of high optical activity form upon electronic excitation. In the complex of proflavine:DNA, the bound dye shows appreciable optical activity when in the ground state but is optically inactive when in the excited state. The mode of interaction between this dye and DNA thus changes appreciably upon electronic excitation. The occurrence of two electronic transitions in the last absorption band of acridine dyes and its implication on the interpretation of the corresponding CD spectra is discussed.
Matrix Methods and Normalization Procedures in Chemical Relaxation
Authors: Hayman H. J. G.
Published: November 2013

Two very general methods for dealing with chemical relaxation in solution near equilibrium are developed in detail along parallel lines; in the first of these the normal modes of relaxation are obtained as linear combinations of a set of basic reactions whereas in the second the normal coordinates are obtained as linear combinations of the deviations of the solute concentrations from those at equilibrium. The general procedures described in the literature, differing both in their basic assumptions (some being based on the theory of irreversible thermodynamics, others on kinetic considerations) and also in the concentration units adopted and the normalization procedures used, form special cases of the above two general methods and are considered from this point of view. The two general methods are compared critically and shown to be complementary since each has its own special advantages and disadvantages. In particular, the significance of the normal modes of relaxation corresponding to infinite relaxation times are shown to be entirely different in the two cases; in the first method these modes are “reactionless” and have little significance whereas the “improper” normal modes obtained by the second method show how the concentrations of the various solutes can be changed without disturbing the chemical equilibrium of the system.
Photochemical Processes in Non‐Equilibrated Franck‐Condon States
Authors: Feitelson Jehuda
Published: November 2013

Solution reactions which occur in pre‐equilibrium excited states, i.e. before the system has reached the lowest thermalized excited state are discussed. Two examples, the photodissociation of β‐naphtholate into a solvated electron plus radical and the acid dissociation of excited β‐naphthol are dealt with in some detail. It is proposed that in these two cases at least the reactions might take place in a, so called, solvent Franck Condon state, i.e. a state in which the solvent has not yet attained the appropriate excited state orientation.
Proton Transfer in Liquid Ammonia Solutions Containing Water and Hydroxide Ion
Authors: Marks Stephen B.
Published: November 2013

The rate of proton transfer in ammonia solutions containing water and hydroxide ion was determined as a function of temperature and concentration by means of PMR spectroscopy. A first order dependence on hydroxide ion and second order dependence on water concentration was found with a rate constant of k3 = 6.1 ± 1.2 × 103 M−2 sec−1 at 25°C and ΔE‡ = 4.5 ± 0.5 kcal/mole. The value of k3 is in good agreement with that reported by other workers.
The Influence of Vacuum, Carbon Monoxide and Hydrogen on Ceria and Zinc Doped Ceria ‐ Electron Spin Resonance Study
Authors: Gideoni Michael , Steinberg Menachem
Published: November 2013

The effects of heating in vacuum, carbon monoxide, and hydrogen on cerium (IV) oxide and zinc oxide‐doped cerium (IV) oxide were investigated by ESR, and a difference in the behavior of the signals obtained for the two preparations was observed. The signal decrease g = 1.940 and g = 1.961 was faster and was obtainable at lower temperatures for the doped oxide than for the undoped sample. The effect of oxygen on these samples is reported and a mechanism is proposed.
On the Synthesis of Glutathione in Human Blood Cells In Vitro
Authors: Bondi E. , Levy J. , Ben‐Yoseph Y. , Hochberg A. , Dimant E.
Published: November 2013

Mature human blood cells depleted of ATP in vitro by preincubation with fluoride, maintain the ability to incorporate glycine into their GSH, presumably by exchange. The incorporation of labelled glycine into GSH, of ATP depleted blood cells, in the presence of added phosphate, is higher than in the nonpoisoned cells. Arsenate accelerates the incorporation of labelled glycine into GSH of ATP depleted blood cells. The inhibitory effect of glucose on the incorporation of labelled glycine into blood cell GSH is thought to be related to the binding of inorganic phosphate. Synthesis of GSH in mature blood cells in vitro was established with labelled cystein and cystine.
Copper (II) Ion Binding in Polyacrylic Acid
Authors: Marinsky J. A. , Imai N. , Lim M. C.
Published: November 2013

The complexing of Cu(II) by polyacrylic acid has been investigated. Potentiometric measurements have been employed to facilitate the experimental program. The stability constant of CuA2, the dominant species observed, has been determined to be approximately 6.5 × 103, a value in good agreement with the formation constant of 4.25 × 103 reported for Cu(acetate)2. The quantitative evaluation of this stability constant is made possible by (1) correcting for complication arising from the large and variable electric field at the surface of the polyelectrolyte in the polymer domain and by (2) expressing the concentration of polymer species in terms of the polymer domain volume.
Determination of Structure and Properties of Acetylacetone Dioxime, Benzoylacetone Dioxime and Bis‐Benzoylacetone Dioximato‐Copper (II): An Ultraviolet Study
Authors: Ben‐Bassat A. H. I. , Adato I. , Sarel S.
Published: November 2013

UV spectra of acetylacetone dioxime (2,4‐pentanedione dioxime = AADO), benzoylacetone dioxime (BADO) and bis‐benzoylacetone dioximato‐Cu(II) [Cu‐ (BADO*)2; BADO* = oxidized BADO] are recorded for aqueous and CHCl3 solutions at different pH values and interpreted. pKa values (1st dissociation constant) for AADO and BADO at constant ionic strenths (μ = 0.12) are derived: pKa (AADO) = 10.50; pKa (BADO) = 9.50, and the influence of molecular structure on acid‐base properties is discussed. Diagrams of possible molecular orbital energy‐level transitions for the oxime and the nitroso chromophores are given. The marked influence of acids (HC1) and bases (triethylamine, TEA) on the shape of the UV spectra of Cu‐ (BADO*)2 is discussed and explained in terms of the acid‐base properties of the nitroso and the oxime groups. Additional evidence has been adduced for the presence of nitroso group and of hydrogen bonds in these complexes.
Photodissociation with Polarized Light
Authors: Bersohn Richard
Published: November 2013

This is a review of a small part of the work on photodissociation with polarized light performed by Kent Wilson and his students [1–4] at the University of California at San Diego and the author and his students [5–7] at Columbia. The physics of the experiment has been presented in a recent review by R.N. Zare [8] who was the first to suggest the utility of such work. We comment on the photodissociation of three molecules — I2,Cd(CH3), and α‐iodonaphthalene.
Valence Angles in Group II Dihalide Molecules
Authors: Coulson C. A.
Published: November 2013

Group II A atoms Ca, Sr and Ba form dihalide molecules some of which are linear and others bent. Two general models are considered to account for this. In the first we suppose a purely ionic structure in which the atoms are polarized by the resulting internal electric field. The polarization energy varies with valence angle; but it is shown that if this model were the correct one, all these molecules should be linear. In the second model we consider the valence states that arise from excitations s2 → sp and s2 → sd. The first of these would lead to a linear molecule, the second to a bent one. Considerations of the energies of excitation to these two valence states together with a similar situation for the positive ions show that bent molecules are favored when the central atom is heavy and when the attached halogens are as electronegative as possible. The experimental results are thus completely explained.
Photodissociation and Half‐Collisions — Computational Viewpoint and Boundary Conditions
Authors: Shapiro Moshe
Published: November 2013

Boundary conditions and quantum mechanical numerical methods for evaluating transition probabilities of photodissociation and half‐collisional processes are presented. Direct and indirect dissociation modes are discussed. In each case we write a set of equations tying the particular boundary behaviour of each dissociation mode to the standard scattering boundary conditions. Numerical schemes based on these equations are presented. The case of competing dissociation reactions and exchange is also considered for the indirect case. When interference between these modes is expected to play a significant role, we show how the quantum jump due to photon and electron impact can be incorporated into the set of equations describing the dissociation. Finally we indicate how a numerical construction of potential surfaces from photofragment spectra and absorption spectra in the continuous and predissociation range can be obtained using these numerical schemes.
Activities of Cobalt Chloride in Molten Magnesium Chloride — Potassium Chloride Eutectic
Authors: Jindal H. L.
Published: November 2013

The activities of CoCl2 in molten MgCl2−KCl at 475° have been determined by measuring the EMF of the galvanic cell.
Fluorination Studies on Glycyrrhetic Acid Derivatives
Authors: Rozen Sh. , Shahak I. , Bergmann E. D.
Published: November 2013

Attempts to introduce a fluorine atom directly at the C‐3 position of the triterpenoidal glycyrrhetic acid 1 by reacting the tosylate 2 with KF, or methyl glycyrrhetate 5 with Et2NCF2CHCIF, failed. The ring A olefin 3 and the rearrangement product 4 were obtained. The homoannular diene 7 was treated with NOF, but only nitroso‐fluorine compounds 8, 9 were isolated. Nitrosyl fluoride was also reacted with olefin 3. A difluoro compound 10 and the expected 2‐keto‐3α‐fluoro compound 11 were obtained. The above two olefins were also reacted with bromine fluoride. Although the diene 7 gave only fluorine‐free compounds 13, 14, the expected fluoro‐bromine compound 16 was obtained from 3. When the 2β‐fluoro‐3α‐bromo compound was treated with Bu3SnH, the bromine atom was replaced by hydrogen and the 2β‐fluoro compound 17 was formed.
Polybarbiturates
Authors: Tahan Menashe , Lander Naftali , Zilkha Albert
Published: November 2013

Several p‐vinylbenzyl malonates were synthesized and condensed with urea to form the corresponding 5‐p‐vinylbenzyl barbiturates, which were polymerized. The gross behavioral changes observed on intraperitoneal (i.p.) administration of the polybarbiturates to mice were compared with those caused by the monomers. The polymers were less toxic but had weaker sedative effects than their respective monomers, and they did not exhibit any prolongation of activity.
Intramolecular Rearrangements in Peptide Derivatives of Anthranilic Acid
Authors: Noguchi Junzo , Kawai Megumi , Hamada Masato
Published: November 2013

The peptidylanthranilic acid ester is stable during the reactions leading to the elongation of peptides. However, when the ester is hydrolyzed, the amide bond of peptidylanthranilic acid is catalytically hydrolyzed at pH 7, owing to the effect of the free carboxyl group of the anthranilic residue, into peptide and anthranilic acid. In this reaction, no decomposition or significant racemization of peptide was observed, and the protected peptide was easily obtained. Only in the case of glycylanthraniloyl derivatives did the rearrangement into peptide and anthranilic acid occur in aqueous solution.
On Lanthionene and Cyclolanthionyl
Authors: Zervas Leonidas , Ferderigos Nicolaos
Published: November 2013

The O,S‐dibenzoyl derivative of N‐carbobenzoxy‐L‐cysteinyl‐L‐serine methyl ester is converted by methanolysis to cyclic products of L‐ and meso‐lanthionine (VI and VIII). This transformation occurs by β‐elimination in the serine moiety followed by addition reactions involving the SH groups and the double bonds thus formed. The structure and configuration of these compounds have been established. The specific rotation of acidic solutions of L‐lanthionine is markedly temperature‐dependent the changes in [α]D being reversible up to 96°. Above this temperature racemization occurs. The above transformation is related to the rearrangements occurring in cystine‐containing proteins treated with alkali and suggests a possible method for synthesis of cyclo‐lanthionyl peptides.
Studies of the Hydrogen Exchange in Aqueous Solutions of Poly‐N5‐(3‐Hydroxypropyl)‐L‐Glutamine
Authors: Hvidt Aase
Published: November 2013

The H‐D exchange of the peptide groups of poly‐N5‐(3‐hydroxypropyl)‐L‐glutamine (PHPG) in D2O solution was studied by an infrared spectrophotometric method. The exchange of the peptide groups of the side chains of the polymer follows simple first‐order kinetics, with exchange rates 3–4 times slower than those of N‐methylacetamide. The kinetics of the exchange of the peptide groups of the polypeptide chain is more complicated and suggests that these molecules are less motile than other polypeptides studied by the exchange method. The observation that the exchange rates measured in solutions of PHPG, as a whole, are much faster than the exchange rates typical of protein solutions is taken as experimental evidence of the shortcoming of PHPG as a model of a protein molecule.
Conformational Behaviour of Non‐Ionizable Polypeptides in Gem‐Diol: Water Solvent Systems
Authors: Lotan Noah , Chen K. , Roche R. S.
Published: November 2013

The conformation of poly‐N5‐(2‐hydroxyethyl)‐L‐glutamine (PHEG) has been investigated in hexafluoropropan‐2,2‐diol‐water mixtures. In spite of the similarity of the circular dichroism spectra obtained in some of these mixtures and in water, NMR and hydrodynamic measurements revealed that macromolecular conformations of various degrees of rigidity are present in the different solvents considered. Homologue polymers of PHEG behave in a similar manner.
Factors Contributing to the Absorption and Fluorescence Characteristics of Pyridoxal Phosphate in Glycogen Phosphorylase b
Authors: Veinberg Shlomit , Shaltiel Shmuel , Steinberg Izchak Z.
Published: November 2013

The Schiff base formed between salicylaldehyde and n‐hexylamine has absorption bands peaked at 255 and 317 nm in non‐polar solvents. In a polar solvent (ethanol) an additional band appears at 405 nm and a shoulder is resolved at 275 nm. The fluorescence band has a peak at 535 nm in non‐polar solvents (with the exception of CCl4) which is blue shifted to 505 nm in ethanol. These spectral data are similar to those of Schiff bases formed between pyridoxal phosphate and aliphatic amines. On the other hand, the spectral properties of the Schiff base of o‐methoxybenzaldehyde with n‐hexylamine are very different. It may thus be concluded that the nitrogen atom of the aromatic ring does not have to be invoked in explaining the spectral properties of pyridoxal phosphate Schiff bases and of pyridoxal phosphate in glycogen phosphorylase. The hydroxyl group seems however to play an important role in determining the spectral properties of Schiff bases of o‐hydroxyaldehydes. The optical rotatory power of the pyridoxal phosphate in phosphorylase is of comparable magnitude for the chromophore in the ground state or the electronically excited state, indicating similarity of mode of binding of the chromophore to the protein in the two electronic states. Measurements of circular dichroism indicate that the “deformer” imidazole citrate affects the interaction of the pyridoxal phosphate with the protein when the cofactor Schiff base is in the ketoenamine form but not when in the enolimine form.
The Active Site of Pancreatic Porcine Elastase: Specificity, Size and Stereospecificity
Authors: Atlas Daphne
Published: November 2013

The kinetic parameters of pancreatic‐porcine‐elastase catalyzed hydrolysis of peptides and peptide esters were determined. The most efficient and specific cleavage occurred at the Ala‐Lys bond of the S‐peptide (RNAse P1–20), RNAse P1–8 octapeptide and the synthetic heptapeptide Ala5‐Lys‐Phe. The active site is extended over eight subsites (about 29 Å) and consists of five subsites from the cleaved bond toward the N‐terminal end and three subsites from the scissil bond toward the C‐terminal end of the substrate. The size of the active center was deduced by comparing the kinetic parameters of the appropriate diastereomers of peptides (of the general formula Ala4‐Lys‐Phe and Alas‐Lys‐Phe), and p‐nitrobenzyl esters of tri‐ tetra‐ and penta‐alanine peptides. Specific local interactions of the various subsites, and their stereospecificity were determined by comparative study of the steady‐state kinetic parameters of the appropriate group‐pairs of substrates. Alignment of the substrate Ala5‐Lys‐Phe‐Ala at the active site was determined by constructing the CPK (space filling model) of elastase, based on its known coordinates, determined at 2.5 Å resolution.
Fluorescent Probes in the Study of the Extended Sites of Proteinases
Authors: Fruton Joseph S.
Published: November 2013

Studies on the kinetics of the cleavage of oligopeptide substrates by pepsin, together with the examination of the changes in fluorescence of dansyl or mansyl peptides upon interaction with pepsin or pepsinogen, give further evidence of the importance of secondary interactions of such substrates with the extended active site of the enzyme and indicate considerable conformational flexibility at the active site of pepsin in response to enzyme–substrate interaction.
Phospholipase B Activity of Purified Phospholipases A from Vipera Palestinae and Naja Naja Snake Venoms
Authors: Shiloah Joseph
Published: November 2013

Phospholipase 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

The 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

Snake 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

The 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.
Preparation and Study of New Lead Compounds
Authors: Galinos A. G. , Triantafillopoulou I.
Published: November 2013

The preparation of complex bromoacids of bivalent lead with pyridine and the study of their physical and chemical properties are reported for the first time. The UV, IR, and X‐ray spectra of these new compounds were obtained and examined.
Scope of the Friedel‐Crafts Synthesis and 1H NMR of Phenoxaphosphinic Acids
Authors: Levy J. B.
Published: November 2013

A 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

The 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

Stepwise 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

A 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

The 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

Stearic 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

We 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

Two 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

Supersaturated 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

Isoalkanes 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

3,6‐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

The 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

Results 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

The 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

The 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

Computer 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

In 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

Hydrochloric 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

Stereoelective 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

A 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

A 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.
Permutational Isomers with Chiral Ligands
Authors: Hässelbarth Werner , Ruch Ernst
Published: November 2013

Problems in permutational isomerism are discussed in terms of double cosets of permutation groups. A short account of chirality vs. achirality of permutational isomers with pairwise mirror image chiral ligands is presented without mathematical detail.
Structure of Nitrosyltris(triphenylphosphine)rhodium, Rh(NO)(P(C6H5)3)3
Authors: Kaduk James A. , Ibers James A.
Published: November 2013

The 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

The 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.