bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Nonequivalence in Some 4 Substituted 2‐Phenyl‐2‐Thiazolin‐5‐Ones
Authors: Glotter E. , Bachi M. D.
Published: November 2013

The NMR spectra of the thiazolinone derivatives IIa‐d and IIIb‐d have been studied. The isopropyl methyl groups in Ha are diastereotopic and possess different chemical shifts, whereas in the tautomeric hydroxythiazole form IVa these groups are enantiotopic and display only one doublet. The diastereotopic methylene groups in IIb and IIIb exhibit a double magnetic nonequivalence: the two CH2 groups have different chemical shifts, however the protons of one methylene are isochronous and show an A2 pattern, whereas the protons within the second methylene are nonequivalent and show an AB pattern. The nonequivalence of the methylene groups is due mainly to the intrinsic diastereomerism of the molecule and is only slightly influenced by temperature, while the nonequivalence of the protons within one of the methylenes is strongly affected by temperature and is related to the different degree of population of the various conformers. Compounds IIc, d as well as IIIc, d are diastereomers by external comparison and the methylene protons show a nonequivalence similar to that of IIb.
DL‐homoserinehydroxamic Acid, DL‐homo‐cystinedihydroxamic Acid, and Derivatives by Hydroxylaminolysis of γ‐Hydroxy‐ and γ‐Thio‐Lactones
Authors: Knobler Y. , Bittner S. , Frankel M.
Published: November 2013

The reaction of α‐amino‐, α‐carbamoylamino‐, α‐benzamido‐, and α‐benzyloxycarbonyl‐amino‐γ‐butyrolactone with hydroxylamine led to the formation of DL‐homoserinehydroxamic acid and α‐N‐acyl derivatives. α‐N‐Benzoyl‐DL‐homoserine‐N‐methyl‐hydroxamic acid and O‐benzylhydroxamic acid ester were prepared by reacting α‐benzamido‐γ‐butyrolactone with N‐methylhydroxylamine and with O‐benzylhydroxylamine, respectively. Hydroxyl‐aminolysis of DL‐homocysteinethiolactone and of N‐acyl‐DL‐homocysteinethiolactones gave homocystinedihydroxamic acid and N,N′‐disubstituted derivatives. Relative reactivities of O‐ and S‐lactones were compared.
Aminoacyloxy Oligostannoxanes
Authors: Frankel M. , Migdal S. , Gertner D. , Zilkha A.
Published: November 2013

Oligomeric stannoxanes having the general formula

magnified image

were prepared by treating amino and N‐acylamino‐acids with polymeric dibutyltin oxide at molar ratios less than 1. Shorter oligomers were built up to higher oligomers by insertion of dibutyltin oxide units.
Pyrolytic Reaction of Carbohydrates. Part IX the Effect of Additives on the Thermal Behavior of Cellulose Samples of Different Crystallinity
Authors: Patai S. , Halpern Y.
Published: November 2013

The thermal decomposition of four different cellulose samples (untreated cellulose, powdered or ball‐milled Whatman 544 filter paper, and micro‐crystalline cellulose) was studied at 250°. In samples heated either alone or in the presence of NaHSO4, Na2SO4, Na3PO4, or NaCl for 2 or 4 hr, weight loss, total organic volatiles, levoglucosan, water, acids, average degree of polymerization, and crystallinity index were determined. The results obtained are tabulated and compared. Whereas pretreatment and crystallinity considerably affect the pyrolytic behavior of the different samples, the presence of additives tends to mask the observable differences.
The Complexes of 2‐acetylpyridine with Cu2+, Ni2+ and Co2+. Part II
Authors: Kirson B.
Published: November 2013

The enolization of 2‐acetylpyridine during the formation of the complex only takes place when the metal ion is not bonded to halogen. The halogen ions of CuII, NiII and CoII form Ketonic complexes with 2‐acetylpyridine. The cobalt in the complex of 2‐acetylpyridine remains divalent even in the presence of factors which usually cause oxidation. The Ketonic complexes of the above metals are not stable in aqueous solution, and in concentrated alcoholic solutions the Ketonic complex may be transformed to the enolic complex.
The Photocycloaddition of Olefins to Unsaturated 3‐Ketosteroids
Authors: Rubin M.B. , Maymon T. , Glover D.
Published: November 2013

Photoadditions of ethylene and of cyclopentene to Δ4 ‐ and Δ4,6‐3‐ketosteroids gave mixtures of cis‐4α,5α and trans‐4α. 5β adducts. In the case of cyclopentene and Δ4,6‐androstadiene‐3‐one‐17β‐ol propionate, only the trans adduct was observed. Cis‐4β,5β adducts were obtained by base‐catalyzed isomerization of the trans adducts. The ratio of cis:trans adducts varied considerably with solvent, temperature, and olefin concentration in steroid reactions but not in reactions with cyclohexenone. The different types of adducts exhibited markedly different ORD curves in agreement with the structures assigned. Carbonyl maxima of trans adducts appeared at shorter wavelengths than maxima of cis adducts in both infrared and ultraviolet spectra. The infrared shifts provide a convenient method for differentiating between cis and trans fused isomers.
The Preparation and Crystal Structure of TlMnCl3, TlFeCl3, TlCoCl3 and TlNiCl3
Authors: Zodkevitz A. , Makovsky J. , Kalman Z. H.
Published: November 2013

The compounds TlMnCl3, TlFeCl3, TlCoCl3 and TlNiCl3 were prepared by heating T1C1 with the corresponding transition metal dichloride in an evacuated ampoule. Atomic positions were determined from powder photographs. All four compounds were found to be related to the perovskite type structure. TlMnCl3 has a cubic structure, space group Pm3m, with ao = 5.025 Å. The other three compounds are hexagonal, probable space group P63mc, with cell dimensions (in Å) a0 = 6.976 and c0 = 6.008 for the Fe compound, a0 = 6.907 and c0 = 5.981 for the Co compound and a0 = 6.863 and c0 = 5.881 for the Ni compound. The three hexagonal compounds are isomorphous. A measureable concentration of basal plane stacking faults was found to occur in TlFeCl3 and also, to a lesser degree, in TlCoCl3.
Organic Fluorine Compounds. Part XLII. The Reaction of Amides of α‐Bromoacids with Potassium Fluoride
Authors: Shahak I. , Rozen S. , Bergmann E. D.
Published: November 2013

The reaction of potassium fluoride with α‐bromocarboxylic acid anilides, substituted in the α‐ or β‐position, causes dehydrohalogenation and gives α, β‐unsaturated anilides. Long‐chain α,α′‐dibromodicarboxylic acid (>C8) anilides give in the same reaction essentially α,αprime;‐di‐fluorocarboxylic acid anilides.
Propylmethylcyclopropenone and Certain Derived Methylenecyclopropenes
Authors: Belsky I.
Published: November 2013

Propylmethylcyclopropenone and certain derived methylenecyclopropenes have been prepared, and their physical properties are reported.
Inhibition of Catalase by Cyanide
Authors: Kremer M. L.
Published: November 2013

The kinetics of the inhibition of the catalatic reaction by cyanide is investigated. The inhibition is formally competitive. Cyanide can combine with both the free enzyme and the active enzyme substrate complex, the latter combination being more labile. The dissociation constant of the enzyme‐substrate‐inhibitor complex for horse liver catalase has been calculated from spectrophotometric data: Ki+ = 14 ± 4 μM. The agreement with the value calculated from kinetic data by Beers for horse blood catalase is satisfactory.
Adsorption and Oxidation of I− and I2 at Solid Electrodes as Functions of the Anode Potential
Authors: Gliksman‐Reis I. , Königsbuch M.
Published: November 2013

The mechanism of the electrochemical oxidation of I− and I2 at the bright Pt and Au electrodes and at platinized Pt ‐ electrodes saturated with H2 or O2, was investigated by voltammetric and adsorption measurements. I131 was used for adsorption detection. I− is strongly adsorbed and electrochemically oxidized to IO−at the bright electrodes as a function of the anode potential, but relatively weak adsorption takes place at the platinized electrodes. I2 shows an apparent desorption as a function of anode potential.
Octahedral Chloride Complexes of Trivalent Actinides and Lanthanides in Solution
Authors: Marcus Y. , Bomse M.
Published: November 2013

The preparation of the crystalline octahedral complex tris (triphenylphosphonium) hexachloro‐americate (III) is reported. The absorption spectra of the octahedral hexachloro complexes of curium (III), americium (III) and most of the trivalent lanthanides in a nitrile solvent are also reported. The dissociation of the hexachloro americate complex anion in the nitrile solvent and in propylene carbonate has been examined. The stepwise association constant K6 for its formation from the pentachloro complex was found to be 150 ± 20 and 60 ± 20 in 85% vol succinonitrile 15% acetonitrile solvent and in propylene carbonate respectively.
Organic Fluorine Compounds. Part 43. Applications of (1,1,2‐Trifluoro‐2‐Chloroethyl)‐Diethylamine as Fluorinating Agent
Authors: Bergmann E. D. , Cohen A. M.
Published: November 2013

The use of (1,1,2‐trifluoro‐2‐chloroethyl)‐diethylamine for the replacement of a hydroxyl group by a fluorine atom has been investigated. Particular attention has been paid to hydroxy‐compounds carrying other functional groups, e. g. carbonyl, ester and amino‐groups and combinations of them.
Sorption of Cyclohexylamine by Montmorillonites
Authors: Yariv S. , Heller L.
Published: November 2013

Infrared spectra indicate that protonation of cyclohexylamine sorbed by montmorillonite depends upon the interlayer cations and the origin of the lattice charge. No protonation occurs with Cs and very little with Na, but with all the other interlayer cations studied cyclohexylammonium ions are formed. Protonation occurs more readily if the lattice charge originates in the octahedral layer. Various associations are inferred between interlayer hydroxides, hydrated cations, ionic and molecular cyclohexylamine and water. The sorption of cyclohexylamine is compared with that of aniline and the validity of the concept “surface acidity” is questioned.
Mössbauer Effect and Resistivity Studies in Fe1.11Te
Authors: Hermon E. , Nolan R. D. , Shtrikman S.
Published: November 2013

Mössbauer effect and electrical resistivity measurements were undertaken on Fe571.11Te. The Mössbauer studies show a magnetic ordering at 68°K, which is identified with the antiferromagnetic transition previously reported for this phase. Comparison of the room and liquid helium temperature spectra indicate that the antiferromagnetic axis lies in the tetragonal plane. The temperature coefficient of the resistivity changes sign near the transition temperature and has a maximum at the transition temperature.
Determination of Chloride Content in Compounds and in Solutions of High Bromide to Chloride Concentration Ratios
Authors: Israel Y. , Gonen L.
Published: November 2013

A method is described for the determination of chloride in compounds and in solutions of high bromide to chloride molar ratios (up to 6300:1). Solutions were boiled briefly with nitric acid to oxidize the bulk concentration of bromide ion to bromine gas which was then flushed with air. Chloride ion was titrated potentiometrically with silver nitrate in 80% i‐propanol‐water medium using a silver‐silver bromide indicator electrode and a chloride‐free reference electrode. Details of the potentiometric techniques peculiar to these titrations are described. The method was successfully applied to the determination of the chloride content of commercially available bromide reagents.
Spiranic β‐Ketoesters and their Pyrazolinones
Authors: Breiman R. , Avramoff M.
Published: November 2013

A number of spiranic β‐ketoesters have been prepared and transformed into the corresponding phenylpyrazolinones by condensation with phenylhydrazine. The structures of the β‐ketoesters and the pyrazolinones, derived from their UV, IR and NMR spectra, are discussed.
Base Induced Isomerization of γ, δ‐Epoxyketones
Authors: Gaoni Y.
Published: November 2013

Base treatment of open‐chain γ, δ ‐ epoxyketones yields usually two cyclopropane derivatives, a trans‐1‐acy1‐2(α ‐ hydroxyalkyl) cyclopropane (II) and a 2‐hydroxy‐3‐oxabicyclo[3, 1, 0] hexane (III). The NMR spectra and some other physical properties of compounds II and III and of some of their transformation products are reported.
Inductive Effects on Molecular Ionization Potentials. III. Primary, Secondary and Tertiary Aliphatic Amines
Authors: Levitt Barbara W. , Levitt L. S.
Published: November 2013

It is demonstrated that the ionization potentials of primary, secondary, and tertiary aliphatic amines correlate very well with the inductive and polar substituent constants, the only seriously deviating value being that for ammonia, itself. The correlation equation is found to be EI = 9.62 + 13.8 ΣσI.
Adsorption of Iodine and Bromine by Polyethylene Sulfide Containing Cotton Fabric
Authors: Avny Y. , Gur‐Arieh Z. , Zilkha A.
Published: November 2013

The adsorption of iodine and bromine by polyethylene sulfide‐containing fabrics was investigated. It was found that the halogens could be adsorbed from aqueous solution as well as from a saturated halogen atmosphere. Adsorption was attributed to complexation by the sulfide bonds in the polymer. Adsorption from aqueous solution led to the formation of a complex with a molar ratio of halogen molecules (X2) to ethylene sulfide units of 1:1, while that from gaseous iodine a ratio of 2 was obtained. Complexation was accompanied by a little degradation of the polysulfide which was attributed to halogenation of the polyethylene sulfide. High adsorption of bromine led to complete degradation of the cotton fabric due to oxidation of the cellulose. The adsorption of polyethylene sulfide in the fabric was much higher than that of homopolyethylene sulfide itself under comparable conditions.
NMR Investigation of the Reaction of 1,1‐Diarylethylenes with Seleninyl Chloride and Diselenium Dichloride
Authors: Elmaleh D. , Patai S. , Rappoport Z.
Published: November 2013

The reaction of 1, 1‐diarylethylenes with seleninyl chloride (SeOCl2) and with diselenium dichloride (Se2Cl2) to yield benzoselenopheno [2,3‐b] benzoselenophens was investigated by NMR. Several reaction intermediates have been tentatively identified in the reaction of 1, 1‐diphenylethylene, but its para‐substituted derivatives yielded no additional mechanistic information. The reaction of 1, 1‐diphenylethylene with thionyl chloride was also studied by NMR. Both the SeOCl2 and the SOCl2 reactions occur through analogous primary addition compounds.
Peptidyl‐tRNA. XIII. The Chromatographic Behavior of Peptidyl‐tRNAvalE. Coli on BD‐Cellulose Column
Authors: Ziv E. , De Groot N. , Rappoport S. , Lapidot Y.
Published: November 2013

The behavior of different peptidyl‐tRNAval from E. coli on benzoylated DEAE cellulose column is described. It was found that the elution pattern of N‐acetyl‐val‐tRNA differs from that of val‐tRNA. Glyn‐val‐tRNA (n = 2,3) and lys‐gly‐val‐tRNA are eluted from the column differently from val‐tRNA. Blocking of the free amino group of the peptide attached to the tRNA causes a further shift of the elution pattern. Val‐gly‐val‐tRNA and phe‐gly‐val‐tRNA are strongly retarded on the column as compared with val‐tRNA, probably because of the hydrophobic interaction between the peptidyl residue and the BD‐cellulose. It is suggested that the differences in the chromatographic behavior of the different tRNA derivatives are due at least partially to differences in conformation.
Inhibitors of Ovine Brain Glutamine Synthetase
Authors: Lustig Nitza , Mor G. , Lichtenstein N.
Published: November 2013

The following carbobenzoxy (Cbz) derivatives of amino acids markedly inhibit ovine brain glutamine synthetase: Cbz‐DL‐phenylglycine, α‐N‐Cbz‐β‐N‐benzyl‐L‐asparagine, Cbz‐L‐phenylalanine, Cbz‐L‐tryptophan, N‐Cbz‐S‐benzyl‐L‐cysteine, and α‐ϵ‐di‐Cbz‐L‐lysine. In all cases tested, the inhibition was of a mixed type. Cbz‐derivatives of aliphatic amino acids inhibit the synthesizing reaction rather weakly. In the presence of methanol (22% v/v) or ethanol (22% v/v) the synthesizing reaction is not, or only slightly, inhibited by Cbz‐derivatives which, at the same molar concentration, are highly inhibitory in the absence of the organic solvents. When, after preincubation with methanol or ethanol, the alcohols are removed by dialysis, the original susceptibility of the enzyme to the inhibitors is restored. The inhibitors are also ineffective in the presence of dioxane (11% v/v). Cbz‐derivatives of amino acids with an additional aromatic group also strongly inhibit the γ‐glutamyl transfer activity of ovine brain preparations. There, too, the inhibition is highly diminished in the presence of organic solvents. Whereas methanol and ethanol lower both the apparent Km and the maximum velocity of the synthesizing reaction, the maximum velocity of the transfer reaction is considerably increased in the presence of these alcohols.
Platinum‐Graphite Biamperometric Indication for the Low Concentration Determination of Antimony, Arsenic and Tin
Authors: Prasad B. B. , Khandelwal G. D.
Published: November 2013

The application of a bi‐electrode system for the determination of Sb (III), As (III) and Sn (II) in dilute solutions is described. The electrode system consists of a platinum microelectrode and a wax‐impregnated graphite electrode. Iodine is used as oxidant. The determinations are quite accurate even in 10−3–10−4M concentration range.
Solvation of Substituted Phenoxide Ions in T‐Butyl Alcohol‐Water Mixtures, from Kinetic Studies of Proton Exchange
Authors: Grunwald E. , Fong D.‐W. , Ralph E.K.
Published: November 2013

Rate constants (k2W or k2A) for proton exchange between a phenol, its conjugate base, and a water or t‐butyl alcohol molecule have been measured in a t‐butyl alcohol‐water mixture by nuclear magnetic resonance. Since k2W and k2A are both high (k2W > 108 sec−1 M−1), the ratio k2W/k2A measures the selective solvation of the O−‐site (of the phenoxide ions) by water and t‐butyl alcohol. In 11.47 mole % t‐butyl alcohol — 88.53 mole % water, k2W/k2A is found to be 14 ± 3 when the ionic reactant is ortho‐bromophenoxide ion, and 32 ± 8 when it is meta‐nitrophenoxide ion. The results suggest that substituents have a marked effect on the selective solvation of the O−‐site.
Energy of Activation and Water Structure
Authors: Perlmutter‐Hayman Berta
Published: November 2013

Instances of temperature‐dependent apparent energies of activation EA, observed for hydrolysis reactions, are briefly reviewed, as are recent calculations according to which the presence of a reactant in two forms which are in mobile equilibrium may lead to a temperature‐dependent EA. These calculations are extended to a consideration of the temperature‐dependence of the specific heat of activation, and to the possibility of more than two forms being in equilibrium. It is shown in some detail how the equilibrium between broken and intact hydrogen bonds in water may be responsible for observed effects.
Solvent Isotope Effects — Second Thoughts About an Old Problem
Authors: Halevi E.A.
Published: November 2013

The commonly held Gross‐Butler theory of isotope effects in mixed H2O‐D2O solvents is reexamined. Special attention is given to the conventional separation of the free energy changes responsible for the isotope effect into contributions from “transfer” and “exchange”. The internal inconsistency of the theory is pointed out and its empirical utility is questioned.
Sorption of Copper Species from Organic Solutions on Anion Exchangers. Part I: Sorption on the Bromide form of the Exchanger
Authors: Cohen R.
Published: November 2013

The sorption of copper species from copper bromide and copper nitrate dissolved in a series of organic solvents onto the bromide form of an anion exchanger (Dowex 1 × 10) was studied. The species sorbed were identified and the products of exchange determined. A mechanism for the sorption from these solutions was suggested.
DTA Traces of Ammonium Perchlorate. Influence of Preheating and Aging
Authors: Simchen A. E.
Published: November 2013

While 4 distinct endothermal processes are known to accompany the thermal decomposition of Ammonium Perchlorate (AP), the DTA thermograms show one endotherm corresponding to the structure transition at 240°C, and two exotherms. The different characteristic points of the DTA thermograms change with the thermal history of the sample and even with aging at ambient temperature. Periods of preheating at 150° lower the initial temperature of self‐heating at a later heating from about 300° for freshly recrystallised AP to about 210° after preheating for 4 days at 150°C. Heating‐cooling cycles above 200° (lower limit) up to 320° (upper limit) show for the first 2‐3 cycles the influence of the known “limited decomposition” of AP. On cooling there is a temperature delay in the structure transition cubic → orthorhombic, up to a constant limit of about 15°, and an apparent comminution of grains.
Dissociation Energies of S2, SO, Te2, SeO and P2 Molecules
Authors: Rai B. , Singh J. , Rai D.K.
Published: November 2013

The ground state dissociation energies of S2, SO, Te2, SeO and P2 molecules have been estimated by fitting the Szöke and Baitz electronegativity potential energy curves to the experimental RKRV curves. The estimates of dissociation energies obtained have been compared with earlier calculations.
Determination of Spurrite, Associated with Calcite, by Means of Differential Thermal Analysis
Authors: Gross S.
Published: November 2013

Differential thermal curves of spurrite‐calcite rocks show two characteristic endothermic peaks at 725–850°C and at 845–990°C, both due to decarbonization. A method for determining the amounts of calcite and spurrite when both are present is proposed using DTA analysis in conjunction with the determination of CO2 in the bulk sample. The results of DTA are confirmed by TG and X‐ray diffraction studies.
2‐Hydroxy‐4‐Benzamidothiosemicarbazide as a Chelating Reagent. Part I‐Studies on its Cobalt(II) and Cobalt(III) Complexes
Authors: Swami M.P. , Rastogi D.K. , Jain P.C. , Srivastava A.K.
Published: November 2013

Three distinct cobalt complexes of 2‐hydroxy‐4‐benzamidothiosemicarbazide, [Co(C8H9N4O2S) (H2O)3] Cl (I), [Co(C3H9N4O2S) (OH) (H2 O)2] (II) and Na [Co(C8H9N4 O2 S) (OH)3] H2 O (III) have been prepared at pH 3.0, 9.0 and 12.5, respectively. Magnetic measurements show subnormal values of the magnetic moment for high‐spin octahedral cobaltous complexes. A possible correlation has been sought in nephelauxetic ratio, calculated from electronic spectral data. The values of 10 Dq, L.F.S.E. and Racah's interelectronic repulsion parameters have also been evaluated. The complex (III) is diamagnetic in nature.
Inductive Effects on Molecular Ionization Potentials. V. Hydrogen Sulfide and Aliphatic Thioethers
Authors: Levitt L.S. , Levitt Barbara W.
Published: November 2013

The ionization energies of thioethers, R2S, have been correlated with the polar substituent constants and the inductive substituent constants. Good correlations are obtained which indicate that the effect of alkyl substituents on the S‐atom is primarily an inductive one.
Propellanes XVII. An Effect of Ring‐Strain on the Synthesis of C‐10 Propellanes
Authors: Tatarsky D. , Kaufman M. , Ginsburg D.
Published: November 2013

Two angularly disubstituted diiodides II and IX were treated with n‐butyl lithium. In the former case [4.4.2] propellane‐3,8‐diene III was obtained. Ozonolysis followed by double intramolecular Dieckmann condensation led to [3.3.2] propella‐3,7‐dione VI. In the latter case cyclization to form [4.2.2] propell‐3‐ene X did not occur. Rather 4,7‐dimethylenecyclooctene XI was obtained.
New ZnS Polytypes of the Family 28L
Authors: Sonnenblick Y. , Kiflawi I.
Published: November 2013

Seven new ZnS polytypes of the family 28L are identified. They are 28L (18 3 5 2), 84R (5 5 5 3 3 3 2 2)3, 28L (26 2), 28L (13 5 7 3), 84R (13 7 3 5)3, 28L (3 3 3 3 3 3 3 3 2 2), and 84R (7 3 3 3 3 3 3 3)3. Indications of polytype transformation are presented and discussed.
A Comparison of Minimum and Expanded Slater Basis Set Difference Density Maps
Authors: Laws Edward A. , Lipscomb William N.
Published: November 2013

A comparison of minimum and expanded Slater basis set difference densities in H2, N2 and B2H6 indicates that minimum basis set results significantly underestimate the transfer and concentration of charge in molecular bonding regions.
Crystalline Di‐Tert‐Butyl Trioxide and Dicumyl Trioxide
Authors: Bartlett Paul D. , Lahav Meir
Published: November 2013

Di‐tert‐butyl trioxide has been prepared at −50° by photolysis of solid di‐tert‐butyl diperoxymonocarbonate and, more conveniently, by the reaction of ozone in Freon 12 (CF2Cl2) or methyl chloride with either dissolved tert‐butyl hydroperoxide or suspended hydrated sodium tert‐butyl peroxide. A low‐temperature procedure for freeing the product from accompanying tert‐butyl alcohol and other impurities is described. The ozone ‐ sodium salt method has also been applied to the preparation of crystalline dicumyl trioxide. These trioxides have the properties previously observed in solution. They are unstable at temperatures above −30°. NMR spectra of the trioxides are reported and compared with those of related compounds. Approximate rate constants for the thermal decomposition of dicumyl trioxide are reported.
Push‐Pull Electronic Activation of Reactions
Authors: Robinson R.
Published: November 2013

Electron delocation, simple or conjugated, is postulated in many reaction mechanisms which are assumed to proceed by way of an activated phase. One‐way processes involving electron displacement are acceptable for additions, but dubious for substitutions. In the text below the bromination of anisole is mentioned. If it is assumed that the Br atom combines with C p‐ to OMe as the result of a full electron displacement, then it becomes necessary to reverse such displacements to remove H from the p‐position. The present hypothesis is that instead of two major translocations the same result could be achieved by a kind of oscillating displacement of smaller amplitude, alternating in opposite directions. In this case, the aromatic structure is never disturbed to any serious extent and side‐reactions are accordingly minimal. The theory is further exemplified by the reactions of acetals and similar types, including the ring‐forms of the sugars. Mention is also made of the probability that reactions of carbonium ions can be interpreted in terms of partial valencies.
Templates and Twinning in Topotaxy
Authors: Zanos Gougoutas J.
Published: November 2013

The oriented growth of a product phase within a reactant crystal (topotaxy) may be directionally unique if directional point‐group symmetry elements of the reactant crystal structure are preserved in the aligned crystal structure of the product. When the specific topotaxy results in an angular divergence between these elements, multiple orientations of the product phase may grow within the pseudomorph (conservative twinning). Irrespective of the specific topotaxy, the total product phase appears to orient so as to conserve the point‐group symmetry elements of the initial lattice. Several examples of conservative twinning in transformations of 2‐iododibenzoyl peroxides and the closely related benziodoxole structures are presented together with matrices describing the specific topotaxies. In most cases, several oriented products are simultaneously and consecutively formed and it is difficult a posteriori to define their individual roles in the transformation. Conservative twinning and sometimes its conspicuous absence provide important clues for the identification of that lattice which controls the alignment of a particular product phase.
The Photochemistry of Solutions of Eu(III) and Eu(II)
Authors: Haas Yehuda , Stein Gabriel , Tenne Reshef
Published: November 2013

Irradiation in the CT band of Eu3+ in aqueous solution, in the presence of scavengers for H atoms, gives rise to formation of Eu2+ and evolution of molecular hydrogen. The kinetics of these processes were studied as functions of the concentrations of Eu3+ and scavenger, of pH, and of light intensity. The results are interpreted by means of a complex scheme in which an excited Eu2+ donates an electron to a proton, the resulting H* initiating a series of dark reactions which lead to evolution of H2 and oxidation of the scavenger.
The Crystal and Molecular Structures of Overcrowded Halogenated Compounds VII. 1:10‐Dichloro‐3:8‐Dimethyl4:7‐Phenanthroline
Authors: Herbstein F. H. , Kapon M. , Rabinovich D.
Published: November 2013

1,10‐dichloro‐3,8‐dimethyl‐4,7‐phenanthroline crystallizes in the triclinic system with a = 7.651(3), b = 7.792(3), c = 12.301(3)Å, α = 108.48(6), β = 82.74(2), γ = 116.53(4)° space group magnified image, Dm = 1.479 g cm−3, Dc = 1.480(5) g cm−3 for two formula units per cell. The intensities of about 2000 reflections were measured by semi‐automatic Weissenberg diffractometer and supplemented by precession diffractometer measurements. The crystal structure was solved by the SEARCH method (Rabinovich and Schmidt, Nature, 211: 1391 (1968)) and refined by full‐matrix least squares methods, using anisotropic temperature factors for non‐hydrogen atoms. The final R‐factor was 0.067 and the “goodness of fit” 0.94. The molecule has an approximate two‐fold axis of symmetry and is appreciably distorted from planarity, the two chlorines being displaced by +1.12Å and −1.15Å from the mean molecular plane; the non‐bonded ClCl distance is 3.082(3)Å. Bond lengths are close to standard values but there are appreciable distortions in bond angles, torsion angles and fold angles. There is hexagonal close packing of stacks of molecules, with van der Waals binding between stacks. Anti‐parallelism of adjacent molecules in a stack suggests that dipole‐dipole forces are important in the intrastack binding. Comparison of the present molecular structure with that of 2,7‐dibromo‐4,5‐bis‐(2‐pyridyl)phenanthrene‐3,6‐diol (Smith and Barrett, Acta Crystallogr., B27: 419 (1971)) shows that the present molecule is the more highly overcrowded.
Gerhard Schmidt's First Researches in X‐Ray Crystallography
Authors: Hodgkin D.C.
Published: November 2013

Early X‐ray studies by Gerhard Schmidt at Oxford aimed at solving the structures of gramicidin S and of tobacco necrosis virus. Although both problems still challenge crystallographers today, conclusions derived at that time are largely supported by recent findings.
The Softness Parameters of Ions. Prediction of the Occurrence of Miscibility Gaps in Molten Salt Mixtures
Authors: Marcus Y.
Published: November 2013

Softness parameters σM for cations and σX for anions, have been calculated as dimensionless quantities for approx. 90 cations and 18 anions. They are given by σM = [σA (Mm+) ‐ σA(H+)]/σA(H+) and σX = [σB(Xa−) ‐ σB(OH−)]/σA(H+) where σA = [σIi(M) + ΔH0h(Mm+)]/m and σB = [‐Ea(X) + ΔH0h(Xa−)]/a are Ahrland's parameters. The new normalized and comparative (to the test ions H+ and OH−) softness parameters are positive for soft ions and negative for hard ones. These parameters, obtained independently, are used with a four‐coefficient equation to calculate coordinate bond energies for metal halides with acceptable accuracy. Considerations of the average coordination in reciprocal molten salt mixture lead to an expression for the metathesis energy change as proportional to the product of the differences in softness parameters of the two cations and the two anions. An empirical one‐coefficient equation involving the softness parameters is proposed to deal with next‐nearest‐neighbor interactions in binary common‐ion molten salt mixtures. These relationships are then used with Blander and Topol's equation to predict the occurrence of irascibility gaps in uni‐univalent reciprocal salt mixtures. The gaps found in other systems are also discussed in terms of the softness of the constituent ions.
Palladium (II) Complexes of Acetylacetone Dioxime
Authors: Ben‐Bassat A. H. I. , Kaszirer F.
Published: November 2013

The formation of a sequence of insoluble Pd(II) compounds was demonstrated by heterometric titration. The species Pd4 AADO (AADO = acetylacetone dioxime), Pd2 AADO and PdAADO were detected and a further compound, Pd(AADO)2 was synthesized. The elemental analysis of Pd2 AADO and Pd(AADOH), is reported. The visible spectrum of Pd/AADO mixtures in solution (at pH = 11) is reported and assigned. IR spectra of Pd2 AADO, Pd(AADO)2 and AADO are recorded and compared, and the structure of the compounds is deduced.
The Water Pressure in the Electrical Double Layer
Authors: Ravina Israela , Zaslavsky Dan
Published: November 2013

A review of the use of the classical Boltzmann distribution equation in the Gouy theory indicates that it is only a special case, neglecting important parameters. It is indicated that the present double layer theory needs to be revised to include also the effect of the electrical field on the water as a dielectric. The pressure in the electrical double layer of montmorillonite clay‐water systems is, thus, evaluated. It is shown that the water pressure in the double layer may reach hundreds of atmospheres.
Conformational Studies on Xanthene, Thioxanthene and Acridan
Authors: Aizenshtat Z. , Klein E. , Weiler‐Feilchenfeld H. , Bergmann E. D.
Published: November 2013

A study of the dipole moments of xanthone, thioxanthone and their halogeno‐derivatives leads to the conclusion that these molecules are not planar. In the xanthene and thioxanthene series, the dipole moments as well as the NMR spectra can be explained by a planar or a non‐planar but rapidly inverting model. In the acridan series, the NMR spectra of N‐acylacridans show that the molecule is non‐planar and inverts. The barrier is 11.7, 13.1 and 13.1 Kcal/mole for the N‐acetyl‐, N‐chloroacetyl‐ and N‐iodoacetyl derivatives, respectively. Equally, it has been observed that at low temperature the rotation around the XCH2 CO bond in the halogenoacetylacridans is hindered.
Photocyclisation and Photocyclodehydrogenation of Stilbene and Related Compounds
Authors: Bromberg A. , Muszkat K. A. , Fischer E.
Published: November 2013

The reversible photocyclisation of cis‐stilbene analogues to the corresponding dihydrophenanthrenes is not slowed down at high viscosities of the medium. Its attenuation at low temperatures is a true temperature effect. Methylation affects the photocylisation significantly only if it results in strong steric interactions in the cyclisation product. Photocyclodehydrogenation of stilbenes with oxygen to the corresponding phenanthrene analogues passes through the 4a, 4b‐dihydrophenanthrenes, and can be sensitized by various compounds at low concentrations. Photo‐oxidation with iodine probably involves dehydrogenation of ground‐state dihydrophenanthrene with atomic iodine. Electronically excited dihydrophenanthrenes may also be involved in the photo‐oxidation.
Some 9‐Amino‐Acridine Derivatives Containing Silicon
Authors: Osman R. , Gertner D. , Shenhar A. , Zilkha A.
Published: November 2013

p‐Tri‐methylsilylphenethylamine and 1‐p‐trimethylsilyphenyl‐1‐amino‐4‐dimethylamino‐butane were reacted with 9‐chloroacridines to give the corresponding N‐substituted 9‐amino acridines, which inhibited the growth of several bacteria but not yeasts.
A Theoretical Study of the Protonation of Purine
Authors: Neiman Z.
Published: November 2013

Energy profiles and molecular binding number (MBN) were calculated for purine and its mono‐protonated forms by the CNDO/2 algorithm. Total energy indicates that the 3,7‐species is the most stable among the protonated isomers, being insignificantly more stable than the 1,7‐analogue. Electronic energy suggests that proton may preferentially be attached to position 3. Charge densities are presented by both Mulliken's population method and CNDO/2.
Metalation Reactions XIII. Effect of the Metalating Agent on the Metalation of Acetylenes
Authors: Becker J. Y. , Brenner S. , Klein J.
Published: November 2013

Methyl‐lithium gave with 1‐phenyl‐1‐propyne and 1‐phenyl‐1‐butyne preferentially the products of monometalation although dimetalation of these compounds is faster than monometalation when butyl‐lithium is used. The product of protonation of dilithiophenylbutyne depends on the condition of the reaction. In the presence of starting material, 4‐phenylbut‐2‐yne and in its absence, 1‐phenylbuta‐1,2‐diene is obtained. Alkylation, silylation and protonation of the lithium derivatives was studied.
Chemical Ecology Evidence for Phosphate as the Only Factor Limiting Algal Growth in Lake Kinneret
Authors: Halmann M.
Published: November 2013

Experiments on the growth of the natural populations of algae and of other microorganisms as a function of the supply of various nutrients was carried out for Lake Kinneret water sampled at about 2 week intervals during January‐June 1972. The addition of orthophosphate caused a rapid rise in biomass, which, after several days, increased to 2‐5 times that in untreated water, as measured by the increase in turbidity and protein content. On the other hand, the addition of sodium or potassium nitrate, ammonium chloride, ferrous ethylenediamine sulfate, sodium silicate or vitamin B12 had no noticeable effect. The plot of biomass produced versus the concentration of added phosphate is a steeply rising function in the range of 0.1 to 1.0 μ molar orthophosphate, which levels off at higher phosphate concentrations, reaching saturation above about 2 μ molar phosphate. Thus, in the range of its natural concentration in Lake Kinneret, 0.09‐0.5 μ molar, orthophosphate is the limiting factor. Above 2 μ molar phosphate, nitrate becomes the limiting factor, as was shown by experiments in which both phosphate (>2 μ molar) and nitrate were added, resulting in extremely abundant algal growth. A model of the reduction of nutrient input was achieved by laboratory experiments, in which the lake water was diluted with distilled water (by 1/4), thus resulting in an approximately proportional (to about 1/4) decrease in biomass. The effect of restoring the natural concentration of either nitrate or orthophosphate was then measured. Added nitrate had no effect, while added phosphate caused a rapid increase in biomass, which after 2‐4 weeks came close to that in the natural lake water. These results indicate that during the spring of 1972, phosphorus has been the only element limiting algal growth in the lake.
Polydepsipeptides I. Synthesis and Characterization of Copolymers of α‐Amino and α‐Hydroxy Acids
Authors: Goodman Murray , Gilon Chaim , Kirshenbaum Gerald S. , Knobler Yehuda
Published: November 2013

Copolymers of the type magnified image were synthesized and characterized. The syntheses of these copolymers were achieved by copolymerization of an α‐amino acid N‐carboxy anhydride and an α‐hydroxy acid anhydrosulfite in the presence of a catalyst. The copolymers were characterized by spectroscopic methods including infrared, circular dichroism and nuclear magnetic resonance. Specific cleavage of the ester bonds by hydroxylamine in the cold confirmed the A‐B block structure where the A represents the poly(amino acid) segment and the B indicates the polyester segment. Measurements by nmr and viscosity indicate that the blocks consist of short chain lengths.
Evaluation of Spectroscopic Parameters for Cobalt (II) Species Sorbed on Ion Exchangers
Authors: Ben‐Zwi N. , Heitner‐Wirguin C.
Published: November 2013

New spectral data for cobalt (II)‐ligand‐solvent systems is reported and spectroscopic parameters are evaluated for various tetrahedral and octahedral species sorted on ion exchangers.
Complexes of Bromine with Macrocyclic Polyethers
Authors: Shchori E. , Jagur‐Grodzinski J.
Published: November 2013

Crystalline complexes of bromine with aromatic macrocyclic polyethers were isolated and the equilibrium constants of complexation of bromine with the aliphatic macrocyclic polyether dicyclohexyl‐18‐ crown −6 and with THF in CCl4‐ethyl bromide solutions were determined by PMR spectroscopy.
Aliphatic, Isoprenoid and Aromatic Acids from an Israeli Shale
Authors: Ikan R. , Bortinger A.
Published: November 2013

Normal fatty acids (C9‐C19); isoprenoid acid (C10); aromatic acids (C11‐C13) of the general formula CnH2 n‐8 O2, and two aromatic acids (C11, C12) of the formula CnH2 n‐14 O2, were identified in a bitumen obtained from shale of Nebi Musa (near Jericho), using chromatographic (GLC) and spectroscopic (MS) methods.
Elementary Steps in the Action of Electron Transfer Proteins
Authors: Faraggi M. , Pecht I.
Published: November 2013

The applicability of the pulse radiolysis technique for understanding the election transfer mechanism in redox proteins is presented. It is also suggested that the observed redox reactivity of the protein is correlated to its structural features.
Consecutive Radical Reactions and the Role of the Protein in the Pulse Radiolysis Of Enzymes
Authors: Lichtin N. N.
Published: November 2013

The reactions of H atoms, OH radicals and hydrated electrons acting as isolated reagents upon ribonuclease in dilute aqueous solution were studied by the technique of pulse radiolysis‐kinetic spectroscopy. The experiments show that initial action of these reagents upon the protein molecule is followed by intramolecular transformations. Two consecutive intramolecular steps have been observed in the reaction of H atoms, with specific rates of approximately 103 sec−1 and 1 sec−1. Some spectral features can be assigned to specific radical sites. For instance, electron adduct to disulfide is formed by the primary action of H atoms at pH 6.6, by the primary action of hydrated electrons at pH 7.6 and by intramolecular reaction of primary product formed by action of OH at pH 7.
Decay of the HO2 and O−2 Radicals Catalyzed by Superoxide Dismutase. A Pulse Radiolytic Investigation
Authors: Rabani Joseph , Klug Dina , Fridovich Irwin
Published: November 2013

The pulse radiolysis technique has been employed in the investigation of the dismutation of superoxide radicals, O−2 and HO2, in the presence of superoxide dismutase in aqueous solutions. The decay of superoxide radicals in the presence of the enzyme was found to be first order in both enzyme and superoxide concentrations. An apparent second order reaction rate constant was found to be about 2 × 109 M−1 sec−1, decreasing slightly as the pH is increased from 5 to 9.5. A mechanism which accounts for all our observations is proposed. It includes two steps: (1) formation of a product (EO−2 or E−) from one enzyme (E) molecule and one O−2 radical ion; (2) regeneration of E by a reaction of this product with an additional O−2 ion radical. The reaction rate constants k = (1.4 ± 0.2) × 109 and k = (1.9 ± 0.6) × 109 M−1 sec−1 were measured at pH = 7 in an oxygenated 0.16 M sodium formate solution.
Radiation Chemistry of Ethylene Glycol, Meso‐Erythritol, 2‐Deoxy‐D‐Ribose and Alkyl Phosphates as DNA Model Compounds
Authors: Schulte‐Frohlinde D. , Von Sonntag C.
Published: November 2013

The γ‐radiolysis of ethylene glycol, meso‐erythritol, 2‐deoxy‐ribose, and alkyl phosphates has been studied in diluted (10−2 M), N2 O‐saturated, deoxygenated aqueous solutions. Products and their G values have been determined. Reaction schemes were derived from complete material balances. In the polyols the primary attack of the radiolytically formed OH radicals and H atoms leads to α, β‐dihydroxyalkyl radicals (A) which eliminate water to give substituted α‐carbonyl‐methyl radicals: (B)

magnified image

Disproportionation reactions of the radicals A and B yield products having the structural units COCHOH and COCH2 —. In ethylene glycol a chain reaction is induced, radical B abstracts a hydrogen from ethylene glycol to give acetaldehyde and radical A. In 2‐deoxy‐ribose the major attack is at C‐1. Products from this radical are 2‐deoxy‐ribonic acid and 2,5‐dideoxy‐ribonic acid. In the formation of the latter a rearrangement is involved. With trimethyl phosphate, the reaction of the solvated electron is only small (2 × 10s 1/mole sec), as shown by pulse radiolysis. Dimethyl and methyl phosphates do not react with the solvated electron to a measurable extent. The attack of the OH radical apparently leads to a cleavage of the alkyl phosphate linkage.
Radiation‐Induced Hydrogen Transfer in Nucleic Acids and Proteins in the Solid State
Authors: Riesz Peter , Smitherman Thomas C.
Published: November 2013

A radiation‐induced transfer of hydrogen from exchangeable to carbon‐bound sites occurs in nucleic acids, proteins and their constituents. The G‐values for this process are similar within a factor of 2–3 to the G‐values for the initial production of stable radicals measured by ESR at room temperature. Unlike the production of radicals, hydrogen transfer in ribonuclease, DNA, and thymine is a linear function of dose in the 0–30 Megarad region. The tritium distributions obtained in proteins by hydrogen transfer are not a measure of the distribution of the “secondary” radicals. From the studies of the effect of temperature, of various scavengers (particularly nitric oxide) and of the dose dependence in the low dose region, it was inferred that for ribonuclease most of the hydrogen transfer takes place during the conversion of the radicals stable at 195°K to the radicals stable at room temperature. The same mechanism also appears to predominate in DNA.
Radiation‐Induced Strand Scissions in Bacterial DNA and their Enzymatic Repair
Authors: Kaplan Henry S.
Published: November 2013

Abundant evidence indicates that lesions induced in DNA, unless they are repaired, may lead to death of cells exposed to ionizing radiations. Although sugar and base damage undoubtedly occur, the lesions which have been most readily quantifiable by biophysical methods and which, if unrepaired, correlate most closely with lethality are single‐strand and especially double‐strand chain breaks. Evidence is presented for the existence of several different systems for the repair of single‐strand breaks, and some of the relevant enzymes are tentatively identified. Chemical inhibitors of these repair processes have been demonstrated. Since these inhibitors act after irradiation and since the consequence of their action is to enhance lethality, they comprise a new class of radiosensitizers.
Variations in the Composition of Bromine Water During Oxidation Reactions
Authors: Ziderman I.
Published: November 2013

A cubic equation has been derived that permits calculation of the composition of aqueous bromine solutions in terms of HOBr, BrO−, Br2, Br−3 and Br− as a continuous function of the pH, the initial oxidant concentration and the mole fraction of oxidant consumed. The calculations were performed by computer for the pH range 0–14 at bromine concentrations (c0) of 10−1 to 10−7 M. Throughout the course of an oxidation at pH 0 and c0= 10−4, bromine water is pure Br2. No Br−3 exists at c0 < 10−3. In the pH range 4–6, dilute bromine solutions are pure HOBr (+ equimolar Br−). For pH > 10, bromine water is pure BrO−, while at pH < 7, no BrO− is present. These conditions are unchanged during oxidant consumption.
Photoionization of Ferrocyanide at Various Wavelengths in Polar Glasses at 77°K
Authors: Moan Johan , Shirom Miriam , Weiss Matitia
Published: November 2013

Solutions of potassium ferrocyanide in 10 N NaOH glass and in ethylene‐glycol/water (3/1) glass at 77°K were irradiated with UV‐light. The ratio of the yields of radicals in the two solvents, as well as the scavenging efficiency of an election scavenger (acrylamide) in 10 N NaOH, were found to change with the irradiation wavelength. From the experiments the conclusion is drawn that the ejection of electrons may occur from different electronic levels depending on the excitation wavelength and that the electrons ejected from a charge‐transfer‐to‐solvent state have higher reactivity with a scavenger than electrons ejected from intramolecular singlet states.