bluuebunny/crossref_metadata_2025 huggingface dataset:
6‐Trifluoromethylindole
Authors: Kalir A. , Pelah Z.
Published: November 2013

6‐Trifluoromethylindole was prepared by reductive cyclization of 2‐nitro‐4‐trifluoromethylbenzyl cyanide. The indole was converted into the corresponding 3‐aldehyde and 3‐carboxylic acid.
Infrared Study of the Adsorption of Benzoic Acid and Nitrobenzene in Montmorillonite
Authors: Yariv S. , Russell J.D. , Farmer V.C.
Published: November 2013

Nitrobenzene and benzoic acid are coordinated through water molecules to the more highly polarizing exchangeable cations in the interlayer space of montmorillonite, but are directly coordinated to NH4+ and possibly also K+: On dehydration of the adsorption complexes the nitrobenzene and benzoic acid become directly coordinated to all of the exchangeable cations investigated. Benzoate ion was also formed in amounts which were dependent on the exchangeable cations.
Organic Fluorine Compounds. Part XXXVII the Preparation of ω‐Amino‐α‐Fluroacids
Authors: Bergmann E.D. , Cohen Amnon
Published: November 2013

γ‐Amino‐α‐fluorobutyric acid (V) and ϵ‐amino‐α‐fluorocaproic acid (VII) have been prepared from the corresponding phthalimido‐α‐bromo‐acid anilides (or other amides) through reaction with potassium fluoride and subsequent hydrolysis.
Amperometric Determination of Cerium and Vanadium, and Cerium and Molybdenum in Their Binary Mixtures Using Two Indicator Electrodes
Authors: Singh D. , Bhatnagar Uma
Published: November 2013

In recent studies in this laboratory, the amperometric method has been applied for the successive determination of cerium and iron [1] and a number of other elements in their binary mixtures [2–3]. In the present investigation this method has been extended for the estimation of mixtures of cerium and vanadium or cerium and molybdenum, using ascorbic acid as titration reagent.
The Reaction of N‐Bromoacetamide with α, β‐Unsaturated Carbonyl Compounds. I. Formation of Bromohydrins from 2‐Hydroxy‐ and 2′‐Hydroxychalcones
Authors: Bien S. , Ber M. , Flohr E.
Published: November 2013

The reaction of N‐bromoacetamide with 2‐hydroxy‐ and 2′‐hydroxychalcones and some transformations of the resulting bromohydrins are described.
Products of the Reaction Between Alcohols and Phosphorus Pentoxide. III. Identification by Infrared Spectrophotometry
Authors: Zangen M. , Bergmann E. D. , Marcus Y.
Published: November 2013

The various compounds obtained by the reaction P4O10 + 4ROH (where R represents hydrocarbon radicals of various length and structure) were identified by infrared spectrophotometry of the fractions separated by column chromatography. The identification was made possible by a comparison between the relative values of the integrated absorption for the P = O, P‐O‐P, P‐O‐C and O‐H bands with those of known standards. For the reaction of phosphorus pentoxide with ethanol, the compounds formed were found to be: mono‐, di‐ and triethyl phosphate, mono‐, (1, 2) di‐ and triethyl‐pyrophosphate; (1, 3) di‐ and (1, 2, 3) triethyl triphosphate; mono‐ and diethyl trimetaphosphate. With other alcohols, only homologs of these compounds were found, but always fewer compounds. Uncertainty between possible isomers was resolved by identification of their acid hydrolysis products.
Extension of the Rate Equations for Enzyme Inhibition
Authors: Kremer M. L.
Published: November 2013

Rate equations for competitive, uncompetitive and noncompetitive enzyme inhibition at low inhibitor concentration are derived. The possibility of distinguishing between these mechanisms is discussed. The relation of these equations to other rate equations and the determination of the total enzyme concentration from inhibition studies are discussed.
Substituent Effects on the N. M. R. Signals of the Angular Methyl Groups in Steroids
Authors: Lavie D. , Greenfield S. , Kashman Y. , Glotter E.
Published: November 2013

The chemical shifts of the angular methyl groups in 131 steroids are tabulated and discussed. Additivity increments of substituents mainly at positions 1, 4, 5 and 6 are derived.
On the U. V. Spectrum of O2−
Authors: Czapski G. , Halperin B.
Published: November 2013

The spectrum of O2− ion was measured in several media. The absorption spectra of O2− in KCl discs, in acetonitrile and the reflection spectrum of KO2 showed the maximum absorption in the range of 240 mμ.

Solutions of KO2 in liquid ammonia and ethylene diamine are characterized by an absorption band in the range of 370–380 mμ.

It is shown that the latter absorption was misinterpreted and is due to the nitrite ion which is formed as a by‐product, rather than to the O2− ion.
Tautomerism and Geometric Isomerism in Arylazo‐Phenols and Naphthols. Part III. Orthohydroxy Derivatives and their Reversible Photochemical Reactions
Authors: Gabor Gavriella , Frei Yael , Gegiou Dina , Kaganowitch M. , Fischer E.
Published: November 2013

Solutions of o‐hydroxy or o‐methoxy azobenzene and phenylazonaphthalenes were studied spectroscopically and photochemically in a wide range of temperatures and solvents. All the hydroxy derivatives exist in solution in the azo form, except for (I) and (IV) which show an equilibrium between the azo and hydrazone forms. The latter predominates in (IV), and in (I) and (IV) is responsible for the so‐called luminescence of o‐hydroxy azo compounds. Luminescence was absent in the other compounds. All compounds except (IV) undergo distinct spectral changes when irradiated with ultraviolet or visible light at temperatures sufficiently low to prevent thermal reversion. In the methoxy derivatives the changes are due to cis‐trans isomerization, as shown also by the activation energy of 23 kcal/mole for the thermal reversion. The same explanation is assumed for the hydroxy compounds. The detailed involvement of the hydrazonic form of (I) in these spectral changes is not clear. In rigid media at −187°C, irradiation of (I) with visible light causes a different spectral change, tentatively ascribed to a “hydrazone” → “azo” conversion. Heating the solutions reverts the changes caused by irradiation. The kinetics of this reversion in the hydroxy compounds are complex, showing that the reactions are either catalyzed or else pass through a hydrazonic form, thereby proceeding with much smaller activation energies and frequency factors. It is suggested that several of the eight possible configurations of the “hydroxy” compounds serve as intermediates in the photochemical and thermal conversions, while others coexist in thermal equilibrium.
2‐Nitro‐4‐Methoxyphenylsulfenyl—A New Protecting Group for the Amino Nitrogen
Authors: Wolman Y.
Published: November 2013

The use of 2‐nitro‐4‐methoxy‐phenylsulfenyl‐(I) as an amino protecting group which is extremely sensitive towards electrophilic attack in the synthesis of amino penicillins (amino‐penicillin and DL‐α‐amino‐benzylpenicillin) is described. Synthesis of few protected dipeptides (2‐nitro‐4‐methoxyphenylsulfenyl‐L‐phenylalanyl‐L‐valine, 2‐nitro‐4‐methoxyphenylsulfenyl‐L‐phenylalanyl‐L‐phenylalanine and 2‐nitro‐4‐methoxyphenylsulfenyl‐L‐valyl‐L‐phenylalanine) demonstrates the use of the protecting group in peptide synthesis.
Benzylation of 6‐Alkylthiopurines in Aprotic Solvents
Authors: Neiman Z. , Bergmann F.
Published: November 2013

Benzylation of 6‐methylthiopurine (I) and its N‐alkyl derivatives in an aprotic solvent usually leads to a single reaction product. Both (I) and its 7‐benzyl derivative are attacked at N‐3, in analogy to the behavior of the corresponding 7‐methylpurine. Reaction of the 9‐benzyl derivative of (I), followed by thiohydrolysis of the thioether group, gives 7, 9‐dibenzyl‐6‐thiopurine betaine. This result is in disagreement with an earlier report that the 9‐methyl derivative is substituted by methyl iodide at N‐3. Re‐investigation shows, however, that in this case too, the 9‐alkyl group directs further attack toward N‐7. Methylation and benzylation of (I) thus obey the same general rules.
The Influence of Supporting Electrolytes on Ionic Equilibria. The Hydrolysis of the Dichromate Ion
Authors: Perlmutter‐Hayman Berta , Weissmann Yael
Published: November 2013

The influence of supporting electrolytes on the equilibrium Cr2O72− + H2O ⇄ 2 HCrO4− has been investigated with a view to comparing this influence with that exerted on the rates of reactions of similar charge‐types. Neither the influence on the equilibrium constant nor that on the rate constant of the back reaction was found to be uniquely determined by the principle of ionic strength. These results, together with examples from the literature, show that there seems to be nothing special about environmental influence on the kinetics of reactions. It is suggested that what makes prediction difficult is the fact that in both cases activity coefficients appear in a combination which is different from that encountered in the mean activity coefficient.

A spectrophotometric method is employed. The value of the equilibrium constant at zero ionic strength has been found equal to 4.4 × 10−2; the heat of reaction is 3.8 Kcal mol−1. The discrepancies between these values and those reported in the literature are discussed.
Some Pseudohalide Derivatives of Perfluoralkyl Selenides
Authors: Welcman N. , Wulf M.
Published: November 2013

Several new pseudohalide derivatives of perfluoralkyl selenides have been prepared and characterized. Their properties are discussed in relation to the analogous alkyl and aryl selenides and perfluoralkyl sulphides. The trends in the properties of these compounds have been found to be in accordance with the expected influence of the strongly electron‐withdrawing perfluoroalkyl groups.
The Diffusion of Divalent Europium into Single Crystals of Potassium Chloride
Authors: Reisfeld Renata , Honigbaum A.
Published: November 2013

The diffusion of europium was studied in single crystals of potassium chloride by the spectrophotometric method. Measurements were carried out in the temperature range 418–550†C. The absorption spectra as well as the fluorescence spectra of crystals showed that europium diffused in its divalent state, being reduced by the crystal field of potassium chloride. The diffusion of europium can be represented by the equation D = 6.45. 10−2exp(‐29.400/RT). It is concluded that the activation energy consists of the sum of the jump energy of Eu2+ and of the enthalpy of solution of EuCl2 in KCl.
The Influence of Counter‐Ions on the Properties of a Polyethylene Phosphonic Acid Membrane
Authors: Kertész D. , De Körösy F.
Published: November 2013

Permselective polyethylene‐phosphonate membranes have been prepared from polyethylene, both by topochemical reaction and by casting from solution. At capacities around 1–2 meq/g these membranes change their electric resistance by more than four orders of magnitude and deswell in acid solutions. The jump in resistance values takes place at different pH according to capacity and cross‐linking of the membrane. The influence of different alkali ions and some tetraalkyl‐ammonium ions on conductivity, swelling and hysteresis of these membranes has been determined. The Li+ ion deswells the membrane and increases its resistance nearly as much as the H+ ion while swelling and conductivity increase in hydroxide solutions with increasing atomic weight of the alkali metals. In non‐alkaline solutions the K+ form has lower conductivity than the Na+ form. Physiological implications of the findings are discussed.
A New Method for Measurement of the Electrical Conductivity of Unsaturated Soils
Authors: Mokady R. S. , Majdan A.
Published: November 2013

A method for the measurement of the electrical conductivity of unsaturated soils is presented. A low frequency A.C. is passed through a soil sample and the consequent voltage drop in the soil is measured potentiometrically. The measurement is carried out at different frequencies and by extrapolating to zero, the electrical conductance of the sample is obtained. The results were in good agreement with those obtained using the D. C. technique. Yet, in the proposed method, difficulties due to electro‐osmosis and polarization are avoided and it is possible to carry out measurements over extended periods of time as there occur only negligible changes in the medium measured. The internal resistance of the differential potentiometer is not great enough; therefore, there still does exist a certain influence of contact‐resistance. The proposed method enables us to make reliable and accurate measurements (relative error — 0.3%) of electrical conductivity even in relatively dry soils because the contact resistance does not interfere in this set‐up.
Calculation of the Standard Free Energy of Cation Exchange in Clay Systems
Authors: Bolt G. H. , Winkelmolen C. J. G.
Published: November 2013

The paper deals with methods for calculation of the standard free energy of cation exchange on clays, by assuming certain models for the distribution of the cations between the adsorbed phase and the equilibrium solution. From a comparison of the results calculated with the help of a hypothetical discharging/charging process of the exchanger in the respective homoionic forms, with those found from graphical integration of In K(exchange) over the equivalent fraction adsorbed (method of Gaines and Thomas), the free energy change of the “associated‐solvent” appearing in the latter procedure is identified with that of the “salt‐free” solvent present in the system. The calculated values of ΔG0 (exchange) corresponding to the chosen models are given for the purpose of comparison with experimental values that are found in, or could be derived from, the relevant literature.
Sorption of Methylene Blue by Montmorillonite Saturated with Different Cations
Authors: Bodenheimer W. , Heller Lisa
Published: November 2013

Sorption of methylene blue by montmorillonite is a cation exchange reaction, but the replacement is not stoichiometric. The degree of dispersion of the clay and the interlayer cations initially present influence the amount of dye sorbed and the nature of the reaction products.
Spectroscopic and Conductance Effects of Conjugated Double‐Bond Systems in Permselective Membranes
Authors: Forgacs C. , Stein G.
Published: November 2013

Changes in the absorption spectrum due to different gegen‐cations of colored cation‐exchange membranes were found and explained by direct interaction between the gegen‐ion and conjugated double‐bond chains in the matrix of the membranes. The decoloration of these membranes as a result of current transfer through them was determined. Tracer experiments showed that during current transfer, Cl− ions become covalently bound to the matrix of the membrane. A theory for the electronic conductance through conjugated double‐bond chains in ionic environment was developed, in consistency with the experimental results.
Rapid Spectrographic Determination of Beryllium in Biological Samples
Authors: Schoenfeld Irena
Published: November 2013

A direct spectrochemical method for the determination of beryllium in biological samples is described. Charred samples are mixed with dilute HCl and used directly for excitation by the rotating‐disc spark technique. Chemical separation of Be is eliminated, simplifying the estimation and increasing the speed at which the analysis can be performed. The limit of detection is 1 ppb of Be in urine samples, 20 ppb in lung and other tissues. The coefficient of variation ranges from 15% to 25%. This precision is sufficient when the determination is intended for rapid diagnostic purposes.
Solid State Reaction of Silver Sulfate and Calcium Oxide
Authors: Shamir D. , Steinberg M.
Published: November 2013

The reaction in the solid state between silver sulfate and calcium oxide was investigated; the reaction proceeded at lower temperatures than previously reported. The solid products were identified by X‐ray diffraction.
The Condensation of 2‐Aminofluorene with α, ω‐Dibromoalkanes
Authors: Barak S.
Published: November 2013

N, N′‐(2‐fluorenyl) derivatives of piperazine, azetidine, pyrrolidine, piperidine and hexamethyleneimine are formed in the condensation of 2‐aminofluorene with α,ω‐dibromoalkanes in the presence of calcium hydroxide or sodium ethoxide. The same products have been prepared also by other routes.
The Preparation and Acid‐Catalyzed Decomposition of N‐Triphenylmethyl Amides
Authors: Dayagi S.
Published: November 2013

Aliphatic and aromatic primary amides react with triphenyl methanol in the presence of small amounts of sulfuric acid in acetic acid, and N‐triphenylmethyl amides are obtained in good yields. The products are cleaved by acids. The decomposition of four N‐trityl amides was studied in various mixtures of acetic acid‐sulfuric acid, and the correlations between the logarithms of the observed first‐order rate coefficients, the concentration of the sulfuric acid, and the acidity functions HO and HA were studied. The kinetic data support a unimolecular rate‐determining step for the solvolysis.
Acylation of Nitrogen Heterocycles under the Conditions of the Schotten‐Baumann Reaction I: Benzimidazoles
Authors: Ben‐Ishai D. , Babad E. , Bernstein Z.
Published: November 2013

The acylation of N‐monosubstituted benzimidazoles with various acid chlorides in ethyl acetate — aqueous bicarbonate mixture was investigated. The reaction, which leads to the fission of the imidazole ring, was found to be strongly dependent on the substitution on both the benzimidazole and the acid chloride used. Electron withdrawing groups in the benzimidazoles were found to facilitate the reaction. Carbobenzoxy chloride and ort ho substituted benzoyl chloride gave the highest yields of the fission products. The carbobenzoxylation and benzoylation of unsubstituted, 2‐monosubstituted and 1,2‐disubstituted benzimidazoles were also investigated.
The Cyclization of Cis‐ and Trans‐ Methoxybenzaldoximes to Methoxy‐3,1,4‐Benzoxadiazepines and Methoxy‐Quinazoline‐3‐Oxides Respectively
Authors: Brown D. J. , England B. T.
Published: November 2013

Cis and trans forms of 2‐amino‐3(4, 5, and 6)‐methoxybenzaldoximes were separated chromatographically and distinguished by their spectra. The trans‐isomers, with triethyl orthoformate, gave 5(6, 7, or 8)‐methoxyquinazoline‐3‐oxide whereas appropriate cis‐isomers gave 7‐ or 9‐methoxy‐3,1,4‐benzoxadiazepine. The structures of the bicyclic products were confirmed by their mass spectra.
Pyrimidines, Part XXII Synthesis and Properties of 5, 6‐Dihalogenouracils
Authors: Pfleiderer W. , Deiss H.
Published: November 2013

The synthesis of various 6‐mono‐ and 5,6 dihalogeno‐uracils is described. It is shown by ultraviolet absorption spectral comparisons in aqueous solutions that the neutral species of all synthesized compounds exist in the dilactam form. The monoanions are formed by loss of a proton from N‐1. pKa values and ultraviolet absorption spectra are reported and the influence of the different halogen substituents are on these properties discussed.
Approach to the Controlled Synthesis of Nucleopeptides I. Nε‐(6‐Purinoyl‐L‐Lysine and β‐(5‐Uracilyl)‐Dl‐Alanine
Authors: Vincze A. , Lachman Ch. , Cohen S.
Published: November 2013

Nε‐(6‐purinoyl)‐L‐lysine has been prepared by acylation of L‐lysine copper complex or Nα‐carbobenzoxy‐L‐lysine with 6‐trichloromethylpurine followed by the removal of the protecting group. β‐(5‐uracilyl)‐DL‐alanine has been prepared by condensation of 5‐chloro‐methyluracil with diethyl acetamidomalonate, followed by acid hydrolysis.
Hydroboration. XXIX. The Hydroboration of Allylic Chlorides a Study of Directive Effects and the Elimination Reaction
Authors: Brown H. C. , Knights E. F.
Published: November 2013

A series of representative allylic chlorides was hydroborated with borane‐tetrahydrofuran and disiamylborane. Hydroboration of allylic chlorides containing a symmetric double bond placed the boron exclusively at the β‐position. Dissymmetric double bonds having more β‐substitution than γ‐substitution react to place the boron predominantly on the γ‐carbon with borane‐tetrahydrofuran and almost exclusively on the γ‐carbon with disiamylborane. In the hydroboration of crotyl chloride with diborane, the rate of elimination of the β‐chloroorganoborane slows markedly after 80% elimination. The 20% of slow elimination reflects the amount of dihydroboration which occurs before elimination. The dialkylborane thus formed probably dimerizes and the dimer undergoes elimination at a reduced rate. The slow elimination is subject to Lewis acid catalysis.
Secondary Isotope Effects Part IV Complex Formation Between Aromatic Hydrocarbons and HCl,
Authors: Halevi E. A. , Ravid B.
Published: November 2013

The isotope effects on complex formation between HCl and variously deuterated benzenes and toluenes have been measured at −80°C, using a differential solubility technique. Both methyl and nuclear deuteration increase the basicity of the hydrocarbon, the two effects being additive in toluene. All the results can be fit with values of: δ FM° = −3.15− cal / g. atom D for methyl deuteration of toluene, and δ FN° = −3.56− cal/g. atom D for nuclear deuteration of either benzene or toluene. The implications of these results for the theory of secondary isotope effects are discussed.
Interaction Dipole Moments in 3‐Arylcycloalkenones
Authors: Meyer A. Y. , Bergmann E. D.
Published: November 2013

The dipole moments of several 3‐aryl‐cycloalk‐2‐en‐1‐ones have been measured and found to deviate from values calculated by summation of the “group moments”. It is shown how such deviations can be used in structural studies.
Structure Determination of Derivatives of α‐Amino‐α, α‐Diphenylacetamide by Mass Spectrometry
Authors: Breuer E. , Sarel S. , Taube Aviva , Sharvit J.
Published: November 2013

The mass spectral fragmentation pattern of a series of derivatives of α‐amino‐α,α‐diphenylacetamide of the types A and B is described. The fragmentation of some related benzhydryl ureas (C) is also included.
Proteolytic Activity of the Amoeba Mayorella Palestinensis
Authors: Edelstein S. , Lichtenstein N. , Lasman M.
Published: November 2013

Lyophilized preparations of the soil amoeba Mayorella palestinensis hydrolyzed hemoglobin. Maximum cleavage occurred near pH 3. Mercapto compounds enhanced the activity only slightly, versene and iodoacetamide had no influence. Synthetic oligopeptides were also hydrolyzed by the preparations. Maximum degree of cleavage occurred at neutral or slightly alkaline pH values. While L‐leucylglycine was readily hydrolyzed, the D‐isomer of this peptide was not attacked. With DL‐leucylglycine 50% cleavage was obtained. Carbobenzoxy‐glycyl‐L‐phenylalanine and DL‐α‐bromoisocaproyl glycylglycine were not hydrolyzed while glycyl‐L‐phenylalanine and DL‐leucylglycylglycine were readily cleaved. Hemoglobin was very poorly hydrolyzed by the preparations at neutral or slightly alkaline pH values. However, preincubation of hemoglobin with the preparations at pH 2.7 rendered it available for further appreciable hydrolysis at pH 8. The significance of these findings for understanding the process of protein digestion in the food vacuole of protozoa is discussed.
A Study on the Mechanism of the Thermal Decomposition of Ammonium Perchlorate
Authors: Burcat A. , Carmon B. , Pelly I. , Steinberg M.
Published: November 2013

The thermal decomposition of ammonium perchlorate in the presence of potassium chloride and chromium (III) oxide was investigated using K36 Cl and51 Cr2 O3 to elucidate the reaction mechanism. Two simultaneous routes are suggested for the decomposition. It was found that double decomposition in vacuo between potassium chloride and ammonium perchlorate does not result in the formation of potassium perchlorate. Chromium (III) oxide was not oxidized by ammonium perchlorate, but oxidation to the hexavalent state took place when potassium chloride was present.
Intermediates in the Rearrangement of O‐Aryloximes to Benzofurans
Authors: Sheradsky T. , Elgavi A.
Published: November 2013

Two intermediates were isolated during the cyclization of 1‐cyclohexyl‐3‐(o‐phenyloximino)‐pyrrolidine‐2‐one to 2‐cyclohexyl‐1, 3‐dihydro‐3‐oxo‐pyrrolo [3,4‐b] benzofuran. Their structures indicate that the reaction mechanism is analogous to the one proposed for the Fischer indole synthesis.
The Thermodynamics of Sodium‐Cesium Exchange on Camp Berteau Montmorillonite: An Almost Ideal Case
Authors: Cremers A. , Thomas H.C.
Published: November 2013

An account of the thermodynamic bases necessary for the presentation of the results of exchange sorption on colloidal materials is given. Particular attention is paid to the consequences of Henry's Law behavior in the trace regions. The arbitrary matter of standard states is briefly discussed. For a very special case, when the energy of adsorption is independent of composition, the temperature‐independent contribution to the entropy of mixing can be deduced. Results of experiments on the Na ‐ Cs exchange on Camp Berteau Montmorillonite illustrate this special case. The corresponding contribution to the free energy of exchange is small, no more than 68 calories per mole, but quite definite. It is speculated that here we have a second order effect, resulting from disparity in the sizes of the exchanging ions, due to edge effects on the clay particles.
Direct Spectrochemical Determination of Fluorine in Organic Compounds
Authors: Schoenfeld Irena
Published: November 2013

A method is given for the direct spectrochemical analysis of fluorine in organic compounds. The determination is based on measurement of the CaF band‐emission. The advantage of the method is its simplicity and convenience, which make it a useful technique in cases where high precision is not required.
Extrusion of Chemically Crosslinked Low‐Density Polyethylene Tubing
Authors: Miltz J. , Narkis M.
Published: November 2013

The conditions of extrusion of a polyethylene‐peroxide mixture in the absence of crosslinking were measured in a Brabender Plastograph. Tubing was formed in a system consisting of an extruder and a crosslinking oven, the latter vertical and directly above the extruder die, pointed upwards. The use of this geometry solved the problem of the intrinsic weight of the tubing. In the present case, the weight acts on a point above the crosslinking oven, where crosslinking to the final value takes place. The weight of the tubing is a problem when working horizontally, in which case special supports are needed, or when working vertically downwards. The main difficulties with the process as described are during startup, but these can be overcome by following a controlled series of temperature changes in the crosslinking oven until steady state is reached. At this point, the oven is isothermal for its entire length, at a temperature of 200°C. Significantly high values of rupture pressure at a high temperature can be achieved for crosslinked tubing containing a filler.
Analytical Applications of the Mercury Coated Rotating Platinum Electrode (MCRPE)
Authors: Koster G. , Ariel M.
Published: November 2013

The combined use of the method of Medium Exchange and a platinum electrode covered by a thin mercury film significantly extends the range of applications of anodic stripping volt‐ammetry. A thin nickel film, interposed between the platinum and the mercury, improves the keeping qualities of the mercury film and facilitates its electro‐deposition. The new technique, among whose advantages increased sensitivity and convenience may be cited, provides a further stepping stone towards the adaptation of anodic stripping for use in the routine analysis of complex samples.
Application of Vapor Pressure Osmometry to the Study of Uranyl Nitrate and Thorium Nitrate Complexes with Tributyl Phosphate
Authors: Apelblat A. , Hornik A.
Published: November 2013

Molecular weights of uranyl nitrate and thorium nitrate solutions in TBP were determined using vapor pressure osmometry. The results seem to show that in carbon tetrachloride uranyl nitrate forms a di‐solvate only, whereas in acetone solution this complex is partly dissociated. Thorium nitrate results have been explained assuming a mixture of two complexes with TBP‐a di‐solvate and a tri‐solvate. The equilibrium constant for the reaction Th(NO3)4 · 2TBP + TBP ⇄ Th(NO3)4 · 3TBP was found to be Kx = 30 at 25°C.
Fulvenes and Thermochromic Ethylenes, Part 53 The Fine Structure of 2‐Arylmethylene‐1,3‐Indandiones; their Dipole Moments and Electronic Spectra
Authors: Weiler‐Feilchenfeld Hannah , Loewenstein Ruth M. J. , Agranat I. , Bergmann E. D.
Published: November 2013

The molar refractions (polarizabilities) and dipole moments of fourteen 2‐arylmethylene‐1,3‐indandiones (I) and the electronic absorption spectra of twenty‐one representatives of this series have been measured. From these data certain features of the fine structure of the compounds have been deduced; inter alia, the carbonyl groups in I are bent away from the benzene ring of the indane moiety, and the 4‐dimethylaminophenyl compound II exists to a significant extent in the zwitterionic form IIA.
Photochromism in Dianthrone and Related Compounds. Part III. Solutions in Aliphatic Hydrocarbons
Authors: Bercovici T. , Fischer E.
Published: November 2013

The photochromism of four non‐thermochromic derivatives of dianthrone, in nonpolar solvents, was investigated. Photocoloration takes place with quantum yields close to unity at temperatures down to −160°C. No photodecoloration takes place. Thermal decoloration is a first‐order reaction, with activation energies of about 13–14 kcal mole−1. At very low temperatures and high viscosities the quantum yield of photocoloration drops sharply, and a new unstable colored modification is formed. The latter converts spontaneously into the normal colored form, at somewhat higher temperatures. Flash experiments show that photocoloration at room temperature takes place within the lifetime of the flash (ca. 5 μs), but this is no longer so at low temperatures.
Internal Conversion in Polyatomic Molecules
Authors: Teller E.
Published: November 2013

It is argued that efficient internal conversion in polyatomic molecules occurs when the energy gap between two potential energy surfaces is sufficiently small, so that, at finite nuclear velocities, the corrections to the Born‐Oppenheimer approximation can lead to significant transition probabilities. In particular this will occur near a conical intersection of two surfaces. An estimate of the transition probability is provided using the Zener criterion.
“Predissociation and Preionization Lifetimes of Polyatomic Ions in the Gas Phase”
Authors: Lifshitz Chava
Published: November 2013

Experimental results concerning predissociations of polyatomic positive ions in the gas phase are reviewed. These include the observation of “metastable” ions; photoionization efficiency curves; “metastable” ion decay curves and isotope effects. Examples are given for the three cases of predissociation. Predissociation by vibration is treated in greater detail and the data are compared with predictions of the quasi‐equilibrium theory (QET). Results concerning preionization of polyatomic negative ions are also included. The theoretical treatment of this problem is presented and discussed. Suggestions are made as to possible future developments in this field.
Study of the Water Molecule in the Gaseous Phase Excited States of H2O, H2O+ and H2O−
Authors: Fiquet‐Fayard F.
Published: November 2013

A short account of the electron configuration of water, including symmetry properties, is given. These simple considerations permit the explanation of the results of photoelectron spectroscopy experiments and photoionization experiments; the 2B2 state of H2O+ is predissociated. Excited states of water are all repulsive or predissociated, the more important fragments being OH2τ, OH2Σ+ and O. Some repulsive states of H2O− are known, but the important low‐lying 2A′ state is unknown.
Pressure Broadening of Line Spectra
Authors: Ben‐Reuven A.
Published: November 2013

A brief survey is given of pressure broadening theory, with particular attention to impact phenomena. The basic collision processes that contribute to line broadening (such as phase shifts, amplitude modulation, reorientation, and sense reversal) and their effects are discussed. Subsequent line shape expressions for the broadening of resonance lines and the transition to nonresonant line shape are presented.
Simplistic Analysis of Reactive Scattering
Authors: Levine R. D. , Bernstein R. B.
Published: November 2013

The relation between the angular distribution of the non‐reactively scattered molecules in a reactive collision and the reaction probability is analyzed in terms of a classical grey sphere “optical model”. Computational results for a model problem are discurred, and the inversion procedure, for the deduction of an opacity function (reaction probability vs. impact parameter) from an observed and a reference angular distribution, is tested. It is concluded that a simple phenomenological analysis of experimental angular distributions can be based on such an optical model.
On the Problematics of the Billiard Ball Model for High‐Energy Displacement Reactions in the Gaseous Phase
Authors: Alfassi Z.B. , Amiel S.
Published: November 2013

The failures of past experiments to validate the existence of the billiard ball model in high energy chemical reactions is discussed and a possible system for critical examination of this model is suggested.
Oxidation of Cyclanols by VV
Authors: Radhakrishnamurti P. S. , Pati S. C.
Published: November 2013

The kinetics of oxidation of cyclanols by Vv in acetic acid ‐ water mixtures at constant acidity is reported. The results are discussed in the light of I strain hypothesis. The postulated mechanism of Waters for cyclanol oxidation is also discussed with reference to this series of alcohols.
Reactions of Some Clays with Ferric‐Ferricyanide (Prussian Brown)
Authors: Yariv S.
Published: November 2013

The intensification of the auto‐reduction of Prussian Brown by clay minerals was studied. The reaction is catalyzed mainly by the expanding clay minerals montmorillonite and vermiculite, but is inhibited by aluminium oxide and allophane, although these also sorb Prussian Brown. The influence of surface acidity and exchangeable cation on the reaction is discussed.
Pyrolytic Reactions of Carbohydrates. Part IV. Anhydro‐Sugar Formation and Transglycosylation in the Thermal Reactions of Various Glucose Derivatives
Authors: Houminer Y. , Patai S.
Published: November 2013

The formation of levoglucosan and 1,6‐anhydroglucofuranose in the thermal decomposition of glucose derivatives, such as methyl and phenyl glucosides and oligosaccharides was studied. It was found that the cleavage of glucosidic linkages in general involves both transglycosylation and hydrolysis. Some conclusions relating to the thermal stability of the various glucosides were drawn and the mechanisms of the reaction are discussed.
Aminolysis and Polymerization of 3‐(p‐Toluenesulfonoxy)Hydantoin
Authors: Zvilichovsky G. , Zucker B.
Published: November 2013

Aminolysis of 3‐(p‐toluenesulfonoxy)hydantoin (I) through two alternative routes led to the formation of series of both methylene‐diurea derivatives(II) and ω‐arylsemicarbazido (N‐arylacetamides) (III). 3‐(p‐Toluenesulfonoxy)hydantoin was found to undergo a novel kind of polymerization reaction induced by triethylamine, yielding a new polymer structure which consists of hydantoin groups combined by a hydrazinic linkage. 5‐Isopropyl‐3‐(p‐toluenesulfonoxy) hydantoin (IV) was prepared here from α‐isopropylmalonic acid diethyl ester, via α‐isopropylmalonohydroxamic acid (V); properties of this compound were also studied.
Stable and Transient Spectra in Pulse Irradiated Metaphosphate Glasses
Authors: Rabani J. , Ottolenghi M.
Published: November 2013

Pulse radiolysis of pure metaphosphate glasses yields a transient spectrum with a maximum at 580 run. This new absorption overlaps that of the permanent coloration at 500nm. The decay of the 580nm species extends over a very large time interval, from ∼10−7 sec to ∼10−2 sec. The effects of doping the glass with CdSO4 and Ce2(SO4)3 are reported and analyzed. The results are interpreted in terms of various electron and hole centers. It is suggested that non homogeneous (spur or cage) kinetics is responsible for the 580 nm decay.
Speculations on a New Mechanism of Crystal Growth from Aqueous Solutions
Authors: Glasner A.
Published: November 2013

The activity of lead ions to form heterogeneous nuclei in supersaturated KCl solutions was shown (in previous publications) to account quantitatively for the effect of these ions on the limit of stability of the supersaturated solutions, the rate of crystallization, and the co‐precipitation of the lead ions with the crystallizing salt. Hence the process of crystal growth is described as the deposition of subcolloidal sized nuclei on the crystal seed. Many otherwise perplexing phenomena recorded in the literature, and observed in studies of various aspects related to the crystallization of KCl and NaCl, prove to be a direct consequence of this mechanism of crystallization. Other examples indicate that heteronucleation and a similar growth mechanism may be prevalent in the crystallization of several salts from their aqueous solutions. Some implications and possible applications of the proposed growth mechanism are also discussed.
Pyrolytic Reactions of Carbohydrates. Part VII. Simultaneous DTA‐TGA Study of the Thermal Decomposition of Cellulose In Vacuo
Authors: Halpern Y. , Patai S.
Published: November 2013

The decomposition of cellulose, in the absence and presence of additives, has been studied in a combined DTA‐TGA (differential thermal analysis — thermogravimetric analysis) system, in which both determinations were carried out simultaneously and on the same sample. The overall process was found to be endothermic in untreated cellulose and in the presence of acidic catalysts, but changed into an exothermal one in the presence of strong bases.
Homogeneous Catalytic Isomerization of Allylbenzene and Phenylbutenes by Some Platinum‐Metal Oomplexes
Authors: Blum J. , Pickholtz Y.
Published: November 2013

The isomerization of Allylbenzene, p‐allylanisole, 4‐phenylbut‐1‐ene and trans‐1‐phenylbut‐2‐ene catalyzed by various ruthenium, rhodium and iridium complexes has been investigated. At the boiling point of the olefins the reaction does not require co‐catalysts. The activity of the complexes studied decreases in the order Ru > Ir > Rh. PPh3 and AsPh3 increase the initial rates of the Rh (III), catalyzed reactions, decrease the activities of Rh (I)‐ and Ir (I)‐complexes and do not affect the Ru (II)‐compound. Different mechanisms for the rhodium‐ and ruthenium‐catalyzed isomerizations are suggested.
Liquid Phase Oxidation of 1, 4 and 1, 2‐Dihydronaphthalene
Authors: Martan M. , Manassen J. , Vofsi D.
Published: November 2013

The two isomeric olefins, 1,2 and 1,4‐dihydronaphthalene, were subjected to autoxidation. Although rates as well as product patterns were entirely different for both olefins, it could be shown that an α‐peroxy radical is a common intermediate with both substrates. The difference in behaviour is caused by the fact that with the 1,4‐isomer chain propagation takes place by hydrogen abstraction, while addition to the reactive double bond occurs with the 1,2‐isomer. By cooxidation experiments of the two olefins a high conversion into an epoxide could be obtained, which was shown to be a reaction intermediate in the formation of β‐tetralone from the 1,2‐isomer. The products obtained on cobalt ion catalyzed oxidation were in agreement with the accepted mechanism for this reaction. The fact that attack by oxygen with both isomers occurs only at the α‐position is contrary to what could be expected on the basis of the thermodynamic stability of the products, but is in agreement with the recently proposed principle of least motion. With base catalysis almost exclusively the dehydrogenation product naphthalene was obtained.
The Radiolysis of Methanol and Methanolic Solutions. VI. Cis and Trans‐Stilbene
Authors: Loeb Anne M. , Lichtin N. N.
Published: November 2013

The use of geometrical isomerization of stilbene as a monitor of radiolytic excitation in methanolic solutions was evaluated using gas chromatographic analysis. No evidence for excitation of stilbene was obtained. The mechanistic significance of the observed isomerization of trans‐stilbene is obscured by the preponderant simultaneous formation of a veriety of other products. The cis‐stilbene used in this work was much less sensitive to ionizing radiation than its trans‐isomer, presumably because of efficient protection by a few percent of 2‐methylnaphthalene present as an impurity.
The Anomalous Behaviour of 18O‐Labelled Compounds. Part IV. Vibrational Spectra of Isotopic Vanadate Ions
Authors: Pinchas S. , Shamir J.
Published: November 2013

The Raman spectra of crystalline hydrated normal and 80 atom% 18O‐labelled sodium orthovanadates were investigated, the bands observed thus being assigned to their respective original modes of vibration. The Raman bands of the aqueous solutions of these vanadates, containing mainly the respective HVO4−2 or DVO4−2 ions, were also studied and in most cases observed to rise in frequency as a result of the 18O‐labelling, as expected on the assumption that the hydrogen bonding between the solvating water molecules and the vanadate ions is weakened by 18O‐labelling the latter.
Thermal Decomposition Kinetics of Ammonium Perchlorate by TGA in Air
Authors: Simchen A. E.
Published: November 2013

TGA curves were obtained in air at atmospheric pressure, at constant and at uniformly increasing temperatures, for small samples of ammonium perchlorate (AP): (A) AP less than three weeks from its recrystallization; (B) AP four to seven months old; (C) pellets of aged material of known grain size. Activation energies calculated from the kinetic evaluation of the TGA curves show differences between the three groups of samples. The greatest activation energies were obtained for group A, the smallest for group C. The “limited decomposition” of AP below 300°C is lowest for group A; it is below 20% as opposed to above 30% for the other two groups. The reaction controlling the weight loss is of second order. An explanation of these facts is attempted by suggesting an activation energy contribution of lattice defects formed on ageing.
A Nitrogen‐Laser Photolysis Apparatus in the Nanosecond Range: The Excited Singlet‐Singlet Absorption Spectrum of Coronene
Authors: Goldschmidt C. R. , Ottolenghi M. , Stein G.
Published: November 2013

The application of a low energy pulsed nitrogen laser as a fast excitation source in photochemistry is described. The experimental problems concerning detection of transients by absorption spectroscopy are discussed. The instrument is applied to the measurement of the absorption spectrum curve of coronene in its lowest excited singlet state.
An Investigation of Proteohormones by Alternating Current Polarography
Authors: Goldstein Rahel , Königsbuch M.
Published: November 2013

The behavior of some proteohormones as mixtures of FSH and LH at different proportions and purity was studied by polarography. Proteins which contain groups of ‐SH and/or ‐S‐S‐, develop in an ammoniacal buffer of CoII or CoIII salts a typical double wave, which is believed to be a catalytic wave of hydrogen evolution. It is called a Brdicka double wave. It depends on various parameters such as concentration of the protein, pH, buffer capacity, temperature, height of mercury current, etc. The influence of changing the various parameters on the height of the wave and on the potential of the maximum of the wave height was studied. Comparison was made among the various hormones and with the simple protein human albumin. The measurements were performed by direct current and alternating current polarography. An attempt is made to investigate the mechanisms of each of the two components of the double wave. Hormone preparations, containing different proportions of LH and FSH, could be characterized.
Photodynamic Action and Singlet Oxygen
Authors: Debey Pascale , Douzou Pierre
Published: November 2013

It was attempted to recreate on molecules of biological interest including enzymes some of the photodynamic effects using the excited species of molecular oxygen. Such a species is produced by a chemical reaction in a separate vessel and is carried into the sample by a stream of gaseous nitrogen.
Photochemistry and Structure of Metal Amine Solutions
Authors: Gaathon A. , Ottolenghi M.
Published: November 2013

The photochemistry of the 670 nm band in fluid sodium amine solutions is investigated by applying flash (optical detection) or steady state (ESR detection) irradiation techniques. The photoregeneration of faded alkali metal solutions induced by exciting the amide decomposition product, is also submitted to flash investigation. In both cases the primary act appears to be the generation of solvated electrons. The available photochemical data are examined in light of a recent spectroscopic study which attributes the 670 nm band to a sodium anion (Na−) and the 850, 920 and 1030 metal bands to K−. Rb− and Cs−, respectively. It is concluded that the photochemical observations provide new evidence for the model involving the alkali metals negative ions. Electron photoejection in a rigid amine glass at −196°C produces a (IR) band which is red shifted relative to that present in an equilibrium liquid solution, frozen to the same low temperature glass. The effect is attributed to two, physically distinguishable, solvated electrons in glasses or, alternatively, to an additional (unidentified) IR species present in the dark equilibrium solutions.
Vibrational biospectroscopy coupled with multivariate analysis extracts potentially diagnostic features in blood plasma/serum of ovarian cancer patients
Authors: Owens Gemma L. , Gajjar Ketan , Trevisan Júlio , Fogarty Simon W. , Taylor Siân E. , Da Gama‐Rose Bianca , Martin‐Hirsch Pierre L. , Martin Francis L.
Published: November 2013

Despite numerous advances in “omics” research, early detection of ovarian cancer still remains a challenge. The aim of this study was to determine whether attenuated total reflection Fourier‐transform infrared (ATR‐FTIR) or Raman spectroscopy could characterise alterations in the biomolecular signatures of human blood plasma/serum obtained from ovarian cancer patients compared to non‐cancer controls. Blood samples isolated from ovarian cancer patients (n = 30) and healthy controls (n = 30) were analysed using ATR‐FTIR spectroscopy. For comparison, a smaller cohort of samples (n = 8) were analysed using an InVia Renishaw Raman spectrometer. Resultant spectra were pre‐processed prior to being inputted into principal component analysis (PCA) and linear discriminant analysis (LDA). Statistically significant differences (P < 0.001) were observed between spectra of ovarian cancer versus control subjects for both biospectroscopy methods. Using a support vector machine classifier for Raman spectra of blood plasma, a diagnostic accuracy of 74% was achieved, while the same classifier showed 93.3% accuracy for IR spectra of blood plasma. These observations suggest that a biospectroscopy approach could be applied to identify spectral alterations associated with the presence of insidious ovarian cancer. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)