bluuebunny/crossref_metadata_2025 huggingface dataset:
PHOTOLYSIS OF GROUP VI HYDRIDES: I. SOLID H2S, H2S2, AND D2S
Authors: Stiles D. A. , Tyerman W. J. R. , Strausz O. P. , Gunning H. E.
Published: May 2006

The primary photochemical step occurring in solid H2S, D2S, or H2S2 was shown to be loss of a hydrogen or deuterium atom. Electron spin resonance spectra are assigned to HS, DS, and HS2, which have not previously been detected in the solid phase, and behavior of these radicals on warming the samples is described. When H2S and D2S matrices were warmed from 77 to 125 °K, the HS and DS spectra collapsed into a doublet and singlet respectively. The hyperfine splitting in HS increased and both signals appeared at lower average g-values than when anisotropically broadened at 77 °K.
ON THE PRESSURE DEPENDENCE OF REACTION RATES
Authors: Golinkin H. S. , Laidlaw W. G. , Hyne J. B.
Published: May 2006

The functional dependence of the rate constant for benzyl chloride solvolysis on pressure is investigated with a view to obtaining reliable values of the activation parameters. It is concluded that a second order polynomial is the best description of this system, reproducing the experimental data with a greater degree of precision than the other published functions. A method for determining the precision of the derivatives of the logarithmic rate is presented, and the pressure dependence of the activation volume is demonstrated. Various systems from the literature are analyzed to demonstrate the general applicability of the quadratic function.
SOLVENT EFFECTS ON THE ULTRAVIOLET SPECTRA OF N,N-DIMETHYLFORMAMIDE
Authors: Mayahi Mahmood F. , Al-Taiar A. H. , Al-Baldawi S. A. , Hussain H. A.
Published: May 2006

not available
PRODUCTION OF HYDRATED ELECTRONS
Authors: Walker David C.
Published: May 2006

not available
THE ADDITION OF CARBOXYLIC ACIDS TO ACETYLENIC COMPOUNDS
Authors: DiPietro J. , Roberts W. J.
Published: May 2006

The free radical induced addition of acetic acid and its derivatives to olefins has been reported recently. As an extension of this reaction, the addition of acetic acid to acetylenic compounds was investigated.Adipic acid was found to be the major product of the reaction of excess acetic acid and acetylene at 110–120 °C under pressure in the presence of organic peroxides. A second oily acidic product with a molecular weight of about 300, not yet identified, was found to the extent of about 2 parts by weight to every 3 parts of adipic acid.Octen-3-oic acid and its anhydride were synthesized from hexyne-1 and excess acetic acid in the presence of organic peroxides. Acetic anhydride was substituted for acetic acid, with the net advantage that acetylene was more soluble in the solvent. The general scope of the reaction was expanded to include other transfer agents, such as acetone, formic acid, and propionic acid.
STUDIES ON CHITAN (β-(1 → 4)-LINKED 2-ACETAMIDO-2-DEOXY-D-GLUCAN) FIBERS OF THE DIATOM THALASSIOSIRA FLUVIATILIS HUSTEDT: II. PROTON MAGNETIC RESONANCE, INFRARED, AND X-RAY STUDIES
Authors: Falk Michael , Smith D. G. , McLachlan J. , McInnes A. G.
Published: May 2006

The extracellular fibers attached to the diatom Thalassiosirafluviatilis have been shown to be pure β-(1 → 4)-linked 2-acetamido-2-deoxy-D-glucan. This polysaccharide was given the systematic trivial name chitan to distinguish it from chitin, which is not a chemically distinct species and which has a radically different X-ray diffraction pattern and infrared spectrum. Proton magnetic resonance studies on the acid hydrolysis of chitan have established that the hydrolysis occurred in three distinct steps: (a) the degradation of the polysaccharide to smaller polymeric units, (b) the production of N-acetylglucosamine from the latter, and (c) the conversion of N-acetylglucosamine into glucosamine and acetic acid. X-ray and infrared studies have shown that chitan has a different macrostructure from that of arthropod chitin. Chitan is completely crystalline and can be converted irreversibly into a form indistinguishable from that of chitin by treatment with hot aqueous lithium thiocyanate. Boiling chitan in water converts it into a second crystalline modification, possibly a hydrate, which can be reconverted into the starting material by drying invacuo. The exceptionally sharp infrared spectrum of chitan allows a more unequivocal assignment of a number of bands common to chitan and chitin, and provides information about the nature of the bands at 1 626 and 1 656 cm−1 in the spectrum of chitin. The correlation of the bands in the region of 840 to 890 cm−1 with the configuration at the anomeric center of glycopyranose derivatives is discussed.
ADDENDUM: IMPROVED SYNTHESIS OF N-ALKYL-ASPARTIC ACIDS
Authors: Abshire C. J. , Berlinguet L.
Published: May 2006

not available
THE THERMAL DECOMPOSITION OF ETHANE: PART II. THE UNIMOLECULAR DECOMPOSITION OF THE ETHANE MOLECULE AND THE ETHYL RADICAL
Authors: Lin M. C. , Back M. H.
Published: May 2006

The rate of the elementary dissociation of ethane into two methyl radicals has been measured in its pressure-dependent region at temperatures from 913–999 °K and at pressures from 1–200 mm. The high-pressure first-order rate constant obtained by extrapolation was in agreement with that obtained at lower temperatures,[Formula: see text]Comparison with calculated Kassel curves showed that the best fit of the data was obtained with the Kassel parameter s = 12 ± 1. The high-pressure first-order rate constant for the decomposition of the ethyl radical was obtained by extrapolation of the data reported in Part I, assuming the rate constant for combination of ethyl radicals is independent of temperature.[Formula: see text]From the measured constant for the dissociation of ethane, the rate constant for the combination of methyl radicals was calculated and compared with the values measured in a lower temperature region. Differences in the values of the rate constants and in the shapes of the unimolecular falloff curves are discussed.
ON THE POSSIBLE CONTRIBUTION OF A MOLECULAR MECHANISM TO THE PHOTODECOMPOSITION OF NITROGEN DIOXIDE
Authors: Preston K. F. , Cvetanović R. J.
Published: May 2006

not available
ARYLATION DES QUINONES PAR LES SELS DE DIAZONIUM: VIII. SUR LES 3-ARYL-1,2-NAPHTOQUINONES
Authors: Asselin Jacques , Brassard Paul , L'ecuyer Philibert
Published: May 2006

The arylation of 1,2-naphthoquinone by benzenediazonium salts, in contrast to previously published results, gave only 3-aryl-1,2-naphthoquinones with poor to fair yields. The best reaction medium has been sought and the implications of the results with regard to the reaction mechanism are discussed.
THE STRUCTURE OF THE MALEIC ANHYDRIDE – ACETYLACETONE ADDUCT
Authors: Bailey R. D. , Strunz G. M.
Published: May 2006

not available
KINETICS AND MECHANISMS OF REACTIONS CATALYZED BY PANCREATIC RIBONUCLEASE
Authors: Ramsden Eileen N. , Laidler Keith J.
Published: May 2006

A kinetic study has been made of the ribonuclease-catalyzed hydrolyses of three cyclic nucleotides, cytidine-2′,3′-phosphate, uridine-2′,3′-phosphate, and N6,O5′-diacetyl cytidine-2′,3′-phosphate. Rates were measured at pH values ranging from 6 to 8.5. The variation of the kinetic parameters with pH showed that the free enzyme possesses two active groups, having pK values of 5.4 and 7.25. When the enzyme–substrate complex is formed, the pK values of the groups are increased to 6.6 and 8.4. The pK values identify these groups as imidazole groups and show that two histidine residues are present at the active site. Since both increase in pK on complex formation, it is concluded that the acid imidazole group binds the substrate, but that the basic imidazole group cannot be concerned in substrate binding and must function only in the hydrolytic step. The results indicate that the pyrimidine base is concerned in the hydrolytic step and not solely in binding, as had been postulated. It is concluded from all of the evidence that four specific sites are present at the active center of the enzyme; three are involved in binding and one in catalysis. It is proposed that the active site of ribonuclease is composed of: the histidine residue in position 12, which catalyzes the hydrolytic step; the histidine residue in position 119, which binds the 2′-ribose oxygen atom in the substrate; the lysine residue in position 41, which binds the phosphate group or anion; and the aspartic acid residue in position 121, which binds the nitrogen atom at N1in the pyrimidine base. A mechanism for enzyme–substrate complex formation and subsequent hydrolysis is proposed.
γ-RADIATION-INDUCED HYDROGEN EXCHANGE REACTION IN LIQUID CYCLOHEXANE – HYDROGEN CHLORIDE SOLUTIONS
Authors: Fletcher J. W. , Freeman G. R.
Published: May 2006

The overall exchange reactions[Formula: see text]have been initiated by radiolysis and measured by a nuclear magnetic resonance spectroscopic method. The reactions occur by a chain mechanism, with a chain length of ~ 104 in a 1 M solution of hydrogen chloride in cyclohexane. The mechanism is complex.The exchange reaction can also be initiated by the photolysis of chlorine or of hydrogen chloride.A chain exchange reaction does not occur between c-C6H12 and DI, D2S, or ND3. These results are consistent with the suggestion that the exchange reaction in the cyclohexane – hydrogen chloride system occurs by a free radical chain mechanism.This type of exchange reaction can cause difficulties in isotopic tracer studies.
KINETICS OF HYDROGEN ABSTRACTION FROM PROTON DONORS BY DPPH
Authors: Singh Surjit , Bhaskar K. R. , Rao C. N. R.
Published: May 2006

The kinetics and energetics of the interaction of DPPH with a variety of hydroxylic compounds have been investigated by electronic and e.s.r. spectroscopy. Deuterium isotope effects on the kinetics have been examined. A model involving hydrogen bonded complexes has been suggested for the hydrogen abstraction reaction.
KINETIC ASPECTS OF THE COPOLYMERIZATION OF TETRAHYDROFURAN WITH PROPYLENE OXIDE. I
Authors: Blanchard L. P. , Singh J. , Baijal M. D.
Published: May 2006

Tetrahydrofuran and propylene oxide were copolymerized in the presence of the catalyst boron fluoride ethyl ether, and various co-catalysts, such as 1,2-propanediol, 1,3-propanediol, and 1,4-butanediol. Ethylene chloride was used as a solvent and as an internal reference for analytical purposes. Reactions were carried out at 0 °C and at atmospheric pressure. Monomer concentrations were determined by vapor phase chromatography, and copolymer molecular structure analyses were carried out by physical and chemical methods including infrared spectroscopy, vapor pressure osmometry, hydroxyl end-group analysis, and chemical reduction of unsaturated linkages.The homopolymerization of tetrahydrofuran did not take place, whereas that of propylene oxide proceeded at a rapid rate. In the copolymerization of tetrahydrofuran with propylene oxide, the rate of disappearance of tetrahydrofuran was found to be independent of its concentration, but varied directly with the concentration of propylene oxide. Under similar conditions, the rate of disappearance of propylene oxide was found to be (a) proportional to the square of its concentration, and (b) inversely proportional to the concentration of tetrahydrofuran.Reactivity ratios varied between 1.3 and 1.8 for propylene oxide and between 0.1 and 0.6 for tetrahydrofuran. Molecular weights obtained by vapor pressure osmometry ranged between 460 and 740, and those obtained by hydroxyl end-group analysis ranged between 520 and 1 660. Infrared spectra confirmed the presence of hydroxyl groups and ether linkages in the copolymers prepared. Results on terminal unsaturation were negative.
INFRARED ABSORPTION OF SINGLE CRYSTALS OF ANHYDROUS SODIUM FORMATE
Authors: Charlton T. L. , Harvey K. B.
Published: May 2006

The infrared absorption of single crystals of sodium formate has been measured in the region of 250 cm−1 to 4 000 cm−1. Thin sections cut perpendicular to the unique axis were employed and spectra were recorded with light polarized at various angles in this plane. It has been possible to assign unambiguously all of the infrared active internal fundamentals of the formate ion including the overlapping v2 and v5 modes. In addition, three lattice modes at 57, 107, and 138 cm−1 have been identified.
THE SUBSTITUENT EFFECT ON VICINAL PROTON COUPLING CONSTANTS IN MONOSUBSTITUTED BENZENES
Authors: Fraser Robert R.
Published: May 2006

The magnitude of the coupling constants between adjacent ring protons in several monosubstituted benzenes has been determined. The values for the interaction between protons ortho and meta to the substituents were in the range of 8.1–8.4 c.p.s. The interaction between protons in the meta and para positions varied from 7.27–7.8 c.p.s. Although the relative insensitivity of these coupling constants to the character of the substituent precludes any accurate assessment of the cause of this variation, the changes in coupling constants are thought to be mainly a reflection of changes in π-electron distribution.
DOUBLE AND TRIPLE RESONANCE EXPERIMENTS ON 2-BROMO-5-CHLOROTOLUENE: SIGNS OF THE RING AND RING-METHYL PROTON COUPLING CONSTANTS
Authors: Kotowycz G. , Schaefer T.
Published: May 2006

Tickling and decoupling (triple resonance) techniques show that the ortho, meta, and para proton coupling constants have the same sign in 2-bromo-5-chlorotoluene. If the ortho coupling in the ring is positive, then decoupling experiments show that the methyl proton couplings to the ring protons in the ortho and para position to the methyl group are negative, while that to the meta position is positive. These signs are in agreement with the σ–π exchange polarization mechanism.
FORMATION OF 7Be IN NUCLEAR REACTIONS INDUCED BY 85-MeV PROTONS
Authors: Lafleur M. S. , Porile N. T. , Yaffe L.
Published: May 2006

Cross sections were measured for the formation of 7Be in targets bombarded with 85-MeV protons. The variation of these cross sections with the mass and neutron-to-proton ratio of the target was investigated.Cross-section calculations were performed on the assumption that 7Be is emitted from the irradiated target as an evaporated particle. Calculated and measured cross sections were in good agreement for medium and heavy targets (A > 55). The calculation underestimated the production of' 7Be in light targets (27 < A < 55).
CHEMICAL SHIFT CHANGES IN FLUOROANIONS OF SOME DIAMAGNETIC SALTS
Authors: Haque Rizwanul , Reeves L. W.
Published: May 2006

not available
THE ELECTROLYSIS OF o-HALOGENOPHENYL-SUBSTITUTED ACIDS
Authors: Woolford R. G. , Lin W. S.
Published: May 2006

The synthesis and electrolysis of a series of o-chloro- and o-bromo-phenyl-substituted acids with two to five carbon chain lengths have been studied. The main products, under the experimental conditions used, were the Kolbe dimers. A complete isolation and identification of all of the important by-products is recorded. Methanol and methanol–pyridine were the solvents for electrolysis.This work represents the first study of the behavior of aromatic halogen substituents during the Kolbe electrolysis. In contrast to many reactions involving aliphatic halogen substituents, no free halogen was produced and no products were obtained, even in trace amounts, where halogen had been lost from the aromatic nucleus. During this investigation, 18 previously unreported compounds were synthesized and their properties were determined.
THE REACTION OF SULFUR DICHLORIDE WITH cis,cis-1,5-CYCLOOCTADIENE
Authors: Lautenschlaeger F.
Published: May 2006

Transannular additions of sulfur dichloride to various cyclic and bicyclic di- and poly-olefins have been disclosed recently. Our observations on the reaction product from cis,cis-cyclooctadiene are reported inasmuch as they supplement the previous findings.
ACTION DES ORGANOMAGNÉSIENS SUR LES COMPOSÉS β-DICARBONYLÉS: I. OBTENTION DES β-DIOLS BITERTIAIRES PAR ACTION DES ARYLMAGNÉSIENS ET DES ALKYLMAGNÉSIENS SUR LES β-DICÉTONES SYMETRIQUES
Authors: Canonne P. , Bilodeau H.
Published: May 2006

The addition of Grignard reagents to dibenzoylmethane and acetylacetone has been reinvestigated. Apart from cleavage products, it has been found that, in the case of acetylacetone, the reaction leads to the corresponding β-ditertiary diols. On the other hand, dibenzoylmethane yields only the β-hydroxyketone.
13C N.M.R. STUDIES: VIII. 13C SPECTRA OF SOME SUBSTITUTED ANISOLES
Authors: Dhami K. S. , Stothers J. B.
Published: May 2006

The 13C nuclear magnetic resonance spectra of a series of 40 substituted anisoles have been obtained to investigate the effects of substitution on the aromatic and methoxyl carbon shieldings. This work extends our studies on the variations of chemical shifts of carbon nuclei in side chains of aryl derivatives. The question of steric hindrance to conjugative interaction of a methoxyl group with an aromatic ring is considered on the basis of the present results. Evidence of a steric effect in compounds in which both ortho positions are substituted is presented.
KINETICS OF THE DECOMPOSITIONS OF ETHANE AND PROPANE SENSITIZED BY AZOMETHANE: THE DECOMPOSITION OF THE NORMAL PROPYL RADICAL
Authors: Lin M. C. , Laidler K. J.
Published: May 2006

The azomethane-sensitized pyrolysis of ethane was studied at low temperatures from 280 to 350 °C. Measurements were made of initial rates of formation of methane, nitrogen, and butane. From the rate of nitrogen production the rate constant for the azomethane decomposition into 2CH3 + N2was[Formula: see text]A similar study of the propane decomposition, at temperatures from 260 to 300 °C, led to the value[Formula: see text]in satisfactory agreement. The rate of decomposition of the n-propyl radical into CH3and C2H4was obtained by comparing the rates of formation of C2H4and n-C6H14; the rate constant was[Formula: see text]The activation energy of 31.4 kcal/mole, together with that of 8.9 kcal/mole for the reverse reaction obtained by Brinton, leads to a value of 20.3 kcal/mole for the dissociation energy of n-CH3—CH CH2at 0 °K, and to a value of 22.8 at 25 °C. The corresponding values for the heats of formation 2of the n-propyl radical are 28.4 kcal/mole at 0 °K, and 23.1 kcal/mole at 25 °C. The dissociation energy of n-CH3CH2CH2—H is deduced to be 99.4 kcal/mole at 0 °K and 99.9 kcal/mole at 25 °C. An energy diagram is constructed for the various reactions of n-C3H7and i-C3H7.
XENON YIELDS IN THE FISSION OF HEAVY ELEMENTS BY MEDIUM-ENERGY PROTONS
Authors: Foksi-Er J. H. , Porile N. T. , Yaffe L.
Published: May 2006

Independent yields for 133Xe and 135Xe and cumulative yields for 133I and 135I in fission of 233U, 235U, 238U, and 232Th with protons of energies 20–85 MeV were measured. Values of Zp, the most probable charge, were obtained by two different methods. The behavior of Zp for 236U and 233U differed considerably from that of 238U and 232Th. Total chain yields were obtained for A = 133 and A = 13.5.
CHEMICAL REACTIONS IN ELECTRICAL DISCHARGES: III. THE POSITIVE COLUMN IN D-C. GLOW DISCHARGES THROUGH OXYGEN
Authors: Rundle H. W. , Gillespie K. A. , Yealland R. M. , Sova R. , Deckers J. M.
Published: May 2006

Discharges through fast-flowing oxygen have been investigated. It has been shown that the electrical field remains constant in the positive column of a particular mode, even in the presence of a large pressure gradient. It was found that five types of discharges could be distinguished and they can be characterized by fluctuations of the voltage at the electrodes. These oscillations are linked with the absence or presence of travelling waves in the column. The conditions of existence of the various discharges are outlined. It has also been shown that the structure of the positive column is not as homogeneous as previously thought. In particular, even at constant field, changes in the electron temperature and the number density of charged species are shown to occur. The change in electron temperature and the presence or absence of oscillations have been shown to affect the rate of production of atomic oxygen and the emission intensity of the spectrum of these discharges.
THE DEUTERIUM ISOTOPE EFFECT AND THE MOLECULAR DYNAMICS OF WATER IN BENZENE
Authors: Moule D. C.
Published: May 2006

Infrared spectra of H2O and D2O in benzene have been recorded and the solubilities of light and heavy water in benzene from 10 to 50 °C measured. Isotope fractionation factors for the distribution of HDO and H2O between the vapor and liquid benzene phases were calculated from the relative solubilities and the vapor pressure ratios of pure H2O and D2O. The isotope equilibrium data was fitted to the expression ln α = −A/T2 + B/T and interpreted by the Bigeleisen formulism. The intramolecular B term was determined from the solvent shifts of the near infrared frequencies and the intermolecular A term calculated by a least squares fit to the isotope equilibrium data. Spectral and equilibrium data were combined to give [Formula: see text].
ARSENIDES OF THE TRANSITION METALS: VIII. SOME BINARY AND TERNARY GROUP VIII DIARSENIDES AND THEIR MAGNETIC AND ELECTRICAL PROPERTIES
Authors: Bennett S. L. , Heyding R. D.
Published: May 2006

The diarsenides of the cobalt and nickel families have been synthesized for magnetic susceptibility studies. The diffraction pattern of the low-temperature modification of nickel diarsenide differs from that of the mineral pararammelsbergite, although the space group is apparently identical and the unit cell dimensions comparable (orthorhombic [Formula: see text] a = 5.770 ± 0.007, b = 5.838 ± 0.006, c = 11.419 ± 0.008 Å). These binary diarsenides exhibit temperature dependent diamagnetic or weakly paramagnetic behavior. Temperature dependence of electrical resistivity indicates that PdAs2 is metallic while PtAs2 is a semiconductor with an energy gap of ~0.17 eV.Substitutional solid solution limits have been determined for various Group VIII transition metal atoms in the pyrite phases PdAs2 and PtAs2, and in the skutterudites RhAs3 and IrAs3. There is no substitution by Ru or Os in PdAs2, by Ni or Pt in PdAsa, by Ru or Ag in RhAs3, or by Os in IrAs3. Very limited substitutions were observed for Rh and Ag in PdAs2, Pd in PtAs2, Pd in RhAs3, and Pt in IrAs3. The limit of Co substitution in PdAs2 is 8.2 ± 0.3 atom %, and of Ni in PdAs2, 56.7 ± 0.3 atom %.In the CoxPd1−xAs2 system, a temperature-dependent paramagnetic contribution corresponding to approximately one uncompensated spin per cobalt ion has been attributed to the t52g low-spin configuration of the Co ion in the pyrite structure. In the NixPd1−xAs2 system, the temperature-independent paramagnetic contribution by the nickel ions is not completely understood.
EUROPIUM OXALATE ION ASSOCIATION IN WATER
Authors: Manning P. G.
Published: May 2006

The partitioning of radiotracer 152/151Eu between aqueous sodium oxalate (Na2L) solutions and toluene solutions of thenoyltrifluoroacetone (HTTA) has been studied as a function of the oxalate concentration. The pH of the aqueous phase was controlled by means of sodium acetate – acetic acid mixtures and the ionic strength (I) by NaCl or NaClO4.At low ionic strengths (~0.05) and [L] ~10−4 M EuL+ formed, but at I = 0.95 and [L] ~10−3 M EuL2− also formed. Stability constants for the 1:1 and 1:2 (metal:ligand) complexes are reported.The magnitudes of the stepwise stability constant ratios are discussed.
CONTRIBUTION À L'ÉTUDE DES SPECTRES DE VIBRATION DU DIBENZOFURANNE
Authors: Davidovics Gisèle , Chouteau Jacques , Reymond Henri
Published: May 2006

The majority of fundamental vibration frequencies of'dibenzofuran and their symmetry types were determined by the analysis of infrared spectra in vapor, liquid, solution, and solid states, and from the study of polarization ratios of Raman lines in the dissolved phase.
The examination of lobinaline and some degradation products by mass spectrometry
Authors: Clugston D. M. , MacLean D. B. , Manske R. H. F.
Published: May 2006

Lobinaline, its derivatives, and its Hofmann degradation products have been examined by mass spectrometry and other spectral and chemical techniques. The results provide independent evidence for the structure of the alkaloid, but indicate that the free base may exist as a mixture of two or three tautomers.
Synthesis of some disubstituted naphthazarins
Authors: Arora Parkash C. , Brassard Paul
Published: May 2006

Some 2,6- and 2,7-disubstituted naphthazarins have been synthesized by cyclizing the corresponding β-(2,5-dimethoxybenzoyl)-acrylic acids. With one exception, it was established that isomerization does not occur and therefore that the method provides unambiguous proof of structure for these naphthazarins. Conversely, the procedure was used to determine the positions of the chlorine atoms in two β-(2,5-dimethoxybenzoyl)-chloroacrylic acids.
Coordination complexes of group (IV) halides. Preparation and infrared spectra of the complexes of group (IV) halides with α-cyanoacetamide as ligand
Authors: Jain Sumer Chand , Rivest Roland
Published: May 2006

Coordination complexes between α-cyanoacetamide as ligand and the group (IV) halides as Lewis acids have been prepared. In all these compounds the ligand has been found to be a bidentate, coordinating to two different metal atoms. The infrared results indicate coordination through the nitrogen of the cyano group and one of the donor atoms of the amide group, probably nitrogen. Some physical properties of the complexes strongly suggest that they are coordination polymers.
Hydrogen abstraction by methyl radicals from benzene and the pressure dependence of the recombination of methyl radicals
Authors: Krech M. , Price S. J. W.
Published: May 2006

With dimethyl mercury and dimethyl cadmium as sources of methyl radicals, values of k1/k21/2 for the reactions

[Formula: see text]

[Formula: see text]have been calculated from 471 to 527 °C over the pressure range 0.3 to 16.2 cm. Extrapolation to the effective infinite pressure region, where it is assumed that E2 = 0, gives E1 = 9.3 kcal mole−1, log A1 = 10.8 (cc mole−1 s−1).
Charge distribution in substituted cyclopentadienyl–manganese–tricarbonyl compounds
Authors: Barbeau C.
Published: May 2006

Photochemical synthesis of mono- and bi-substituted cyclopentadienyl–manganese–tricarbonyl compounds with triphenyl-phosphine, arsine, stibine, and bismuth is reported. The infrared absorption and proton magnetic resonance spectra are discussed in relation to the distribution of negative charges among the ligands. The dipole moments were measured and the partial dipole moments for the group manganese–triphenyl compound in these derivatives are calculated and discussed.It is shown that the distribution of negative charges occurs principally between the CO and phenyl ligands and that the donor–acceptor behavior of the phenyl ligands depends mainly on the phenyl group and to a very small extent on the central atom.
Kinetics and mechanism of bromination of styrenes
Authors: Yates Keith , Wright W. V.
Published: May 2006

The kinetics of bromination of six substituted styrènes (3-fluoro-, 3-chloro-, 3-bromo-, 3,4-dichloro-, 3-nitro-, and 4-nitro-) in anhydrous acetic acid have been investigated at several temperatures. At 25.3 °C the reactions follow the rate expression

[Formula: see text]The rate constants for the second order process show a good linear free energy relationship of the log k versus σ type with ρ = − 2.24. (The value obtained at 35.3 °C is − 1.93.) No simple rate-substituent dependence is obtained for the more complex third order process. Activation parameters have been obtained for the second order brominations, the ΔS≠ values being large and negative. Bromination of styrene in the presence of a large excess of acetate or nitrate gives only two products in each case, the α,β-dibromide and the α –acetoxy β-bromide or α -nitrato- β -bromide respectively.The magnitude of the reaction constant ρ, the values of ΔS≠, and the reaction products all support a mechanism involving a highly unsymmetrical bromonium ion intermediate.
Coordination complexes of gallium(III) and indium(III) halides. I. Complexes with triarylphosphines
Authors: Carty A. J.
Published: May 2006

The preparation and partial characterization of some new complexes of gallium(III) and indium(III) halides with triphenylphosphine, tri-p-tolylphosphine, and tri-p-methoxyphenyl-phosphine are described. Complexes of gallium(III) halides with the chelating diphosphine l,2-bis(diphenylphosphino)ethane are also described. Conductivity and infrared spectral measurements have been used to interpret the stereochemistry of these compounds.
Some cleavage reactions of compounds containing As—As or S—S bonds
Authors: Cullen W. R. , Dhaliwal P. S.
Published: May 2006

The reaction between diarsines and disulfides to give compounds containing As—S bonds has been further investigated. Compounds with S—S bonds are cleaved by (CH3)2AsH and HCl. CF3SCl cleaves diarsines. Compounds with As—S bonds are cleaved by CF3SCl and (CH3)2AsH. New compounds obtained are C6H5SAs(CH3)2, C6H5SSCF3, CH3SSCF3, and C2H5SCH3.
The alkaloids of Lycopodium cernuum L. I. The structures of cernuine and lycocernuine
Authors: Ayer W. A. , Jenkins J. K. , Valverde-Lopez S. , Burnell R. H.
Published: May 2006

Structures IV and V are proposed for cernuine and lycocernuine, respectively, the major alkaloids present in Lycopodium cernuum L. The chemical and physical properties on which these structures are based are described. A possible mode of biogenesis of these alkaloids is discussed.
Reductive cleavage with metal in liquid ammonia. II. Olefin formation in attempts at selective cleavage of methyl S-benzyl-4,6-O-benzylidene-3-O-methyl-2-thio-α-d-altropyranoside and its S-methyl analogue by sodium metal in liquid ammonia diluted with 1,2-dimethoxyethane
Authors: Nayak U. G. , Sharma M. , Brown R. K.
Published: May 2006

When methyl S-benzyl-4,6-O-benzylidene-3-O-methyl-2-thio-α-d-altropyranoside (VI) in liquid ammonia was treated with metallic sodium, a reductive cleavage occurred to give methyl 3-O-methyl-2-thio-α-d-altropyranoside in an 85% yield. In the solvent 1,2-dimethoxy-ethane, the reaction of sodium with VI gave little, if any, reductive cleavage. Instead, a base-catalyzed elimination of methanol took place to give the two olefins methyl,S-benzyl-4,6-O-benzylidene-2,3-didehydro-3-deoxy-2-thio-α-d-erythro-hexopyranoside (IX) and S-benzyl-4,6-O-benzylidene-l,2-didehydro-1-deoxy-3-O-methyl-2-thio-d-ribo-hexopyranose (X). Under the alkaline reaction conditions, IX isomerized partly to a third olefin, methyl.S-benzyl-4,6-O-benzylidene-3,4-didehydro-3-deoxy-2-thio-α-d-erythro(threo)-hexopyranoside (XI).In the mixed solvent liquid ammonia and 1,2-dimethoxyethane, sodium reacted with VI to give a 33% yield of the 2,3-olefin IX. Other products, no doubt present, were not isolated in this experiment.Three analogous olefins were obtained from the reaction of sodium or basic reagents with methyl 4,6-O-benzylidene-3-O,S-dimethyl-2-thio-α-d-altropyranoside (VIa) in 1,2-dimethoxyethane.
The selective phosphylation of ethanolamine
Authors: Greenhalgh R. , Weinberger M. A.
Published: May 2006

In nonaqueous solvents under conditions where phosphylation of either of the functional groups of ethanolamine can occur, it is found that phosphofluoridates react exclusively with the hydroxyl group. This O-phosphylation appears to be specific for phosphofluoridates, since phosphochloridates, tetraethyl pyrophosphate, and ethyl N,N-dimethylphosphoramidocyanidate react predominantly with the amino moiety. However, with these compounds the reaction is not as specific, some O-phosphylation being observed, especially with the last compound. Possible reasons for this difference in behavior are discussed.
Kinetics of α-chymotrypsin action. III. Mechanisms of inhibition
Authors: Kaplan Harvey , Laidler Keith J.
Published: May 2006

An experimental study was made of the α-chymotrypsin-catalyzed hydrolysis of N-acetyl-l-tyrosine ethyl ester, inhibited by indole and phenol. Indole inhibits noncompetitively, and analysis of the behavior shows that it binds to the enzyme and the acyl enzyme but not to the Michaelis complex; by binding to the acyl enzyme, it blocks deacylation. Phenol exhibits competitive behavior, two molecules of phenol being bound to the free enzyme in a forced-order sequence. It is concluded from the kinetics that there is either no binding of phenol to the acyl enzyme, or binding which does not affect the rate of deacylation. A general mechanism of inhibition is shown, to explain in a quantitative manner these and other inhibition results.
Stresses and strains in adsorbent–adsorbate systems. VI
Authors: Farhan F. M. , Lakhanpal M. L. , Flood E. A. , Evans Brian
Published: May 2006

The effects of some changes of ambients on the dimensions of an activated carbon rod are presented. The emphasis is on the regions where anomalous contractions occur. It is suggested that dimensional changes can be used to estimate adsorption potentials of liquids of very low vapor pressures where adsorption isotherms cannot be measured by the usual methods.
Thermodynamic properties of dense fluid mixtures
Authors: Orentlicher M. , Prausnitz J. M.
Published: May 2006

By using the properties of hard-sphere systems as a point of departure, equations are derived for the residual properties of mixtures of real simple fluids at liquid-like densities. The essence of the derivation lies in a functional expansion of g(r) exp

[Formula: see text] about its hard-sphere value. The results obtained are useful for interpreting, correlating, and extending experimental data for both concentrated and dilute liquid solutions.
Pyrochlores. II. An investigation of La2Ce2O7 by neutron diffraction
Authors: Brisse François , Knop Osvald
Published: May 2006

The lattice parameter of La2Ce2O7 fired at 1 400 °C was found to be 5.5700 ± 7 Å (at 20 ± 2 °C). Its crystal structure was of the disordered fluorite rather than the pyrochlore type. The degree of order in the structure could not be established from the neutron powder diffraction pattern, but it is likely that the metal and oxygen atoms were distributed at random, possibly with some tendency to short-range ordering. It would appear that for Ce4+ the ionic size requirements for the formation of the pyrochlore structure are no longer satisfied, and that the cerates M23+Ce24+O7 are outside the stability limits for 3–4 pyrochlores.
Tracer diffusion of mercury in thallium amalgams
Authors: Foley W. T. , O'Sullivan Kathleen
Published: May 2006

The tracer diffusion coefficient of mercury in thallium amalgams was measured by the capillary-reservoir technique at 25 °C. The values of 105D in cm2 s−1 at 0.0394, 0.0992, 0.1515, 0.2093, 0.2809, 0.3575, 0.4128 mole fraction thallium were 1.27, 1.06, 0.97, 0.92, 0.75, 0.71, and 0.65 respectively, with standard deviations in 10−5 (cm2 s−1) of 0.089, 0.167, 0.024, 0.028, 0.024, 0.007, and 0.017 respectively. The data are compared with the data obtained in the study of the mutual diffusion coefficient for this system and with the tracer diffusion coefficient of thallium.
Pyrrole chemistry. VI. Syntheses and electrophilic substitution reactions of some 3-substituted pyrroles
Authors: Anderson Hugh J. , Huang C. W.
Published: May 2006

The Friedel–Crafts acetylation of methyl 2-pyrrolecarboxylate, 2-pyrrolecarboxaldehyde, and 2-pyrrolecarbonitrile was investigated and found to give 4-substitution mainly or exclusively. The 4-acetyl-2-substituted products were converted into the 4-acetyl-2-acid, and then into 3-acetylpyrrole (methyl 3-pyrryl ketone). The Friedel–Crafts isopropylation and the bromination of both methyl 3-pyrrolecarboxylate and 3-acetylpyrrole were found to produce almost exclusively 5-substituted products.
Establishment of configuration by nuclear magnetic resonance spectroscopy. II. o-Benzoquinone cyclic ketals
Authors: Fraser Robert R. , Reyes-Zamora C.
Published: May 2006

It has been shown by nuclear magnetic resonance spectral analysis that 4a,8a-dimethoxy-4a,8a-dihydro-1,4-benzodioxan (I) and 4a,8a-dimethoxy-4a,5,6,7,8,8a-hexahydro-1,4-benzo-dioxan (II) possess the trans stereochemistry at the ring junction.
Reactions of nitro sugars. VI. Nucleophilic additions and elimination–additions
Authors: Baer Hans H. , Neilson Thomas , Rank Werner
Published: May 2006

2-Substituted methyl 3-deoxy-3-nitro-β-d-glucopyranosides were obtained in good yields by nucleophilic additions to methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitro-β-d-erythro-hexopyranos-2-enide (I) or by elimination–addition reactions with methyl 3-deoxy-3-nitro-β-d-glucopyranoside (II) or its 2-O-acetate III. Substituents introduced in the 2-position were the methoxy, ethoxy, benzoxy, benzylthio, diethylamino, piperidino, and N-(carboethoxymethyl)-amino groups.
Électrochimie en milieu chlorhydrique concentré: réduction du germanium(IV)
Authors: Benoit R. L. , Gauthier M. , Plichon V.
Published: May 2006

not available
Reactions of 88Sr with protons of energies7–85 MeV
Authors: Sachdev D. R. , Porile N. T. , Yaffe L.
Published: May 2006

Excitation functions for the (p,xn) (x = 1–5), (p,p3n), and (p,2pxn) (x = 1, 3, 4) reactions induced in 88Sr by protons of energy from 7 to 85 MeV have been measured by radiochemical methods. Cross sections for the individual isomeric species for the products of (p,2n), (p,3n), (p,4n), and (p,p3n) reactions are also presented.Excitation functions for each of the (p,2p3n) and (p,2p4n) reactions exhibit two peaks, the first of which is assigned to (p,α n) or (p,α 2n) reactions from threshold considerations. The experimental results are compared with Monte Carlo calculations using the codes of Chen et al. for the cascade stage and Dostrovsky et al. for the evaporation stage. The comparison suggests that the calculations of Chen et al. overestimate the extent of compound nucleus contribution at high energies.
Relative signs of six proton coupling constants in isopropenylacetylene. The effect of the acetylenic group on the chemical shift of the protons
Authors: Hutton H. M. , Schaefer T.
Published: May 2006

The relative signs of the six proton coupling constants in isopropenylacetylene have been determined by multiple resonance techniques. The signs of the long-range couplings agree with those predicted by the Dirac vector model. The geminal ethylenic proton coupling is taken as positive. It is concluded that the methyl group does not interact with the triple bond via a hyperconjugative mechanism. The ethylenic protons are less shielded than in propene, whereas the opposite is expected on the basis of the magnetic anisotropy of the triple bond. This apparent anomaly can be rationalized quantitatively with a model given by Castellano and Lorenc and all four shifts relative to propene are predicted satisfactorily.
Caerulomycin, a new antibiotic from Streptomyces caeruleus Baldacci. II. Structure
Authors: Divekar P. V. , Read G. , Vining L. C.
Published: May 2006

The antibiotic caerulomycin is shown to be 4-methoxy-2,2′-dipyridyl-6-syn-aldoxime (I) by chemical and spectroscopic studies.
1,2,4-Dithiazole-3-thiones and derivatives
Authors: MacDonald J. W. , McKinnon D. M.
Published: May 2006

5-Aryl-1,2,4-dithiazole-3-thiones may be made by sulfurization of N-aroyl-isothiocyanates, -thionocarbamates, or -dithiocarbamates. Attempts to produce 5-alkyl compounds failed, whereas an alternate cyclization of a reaction intermediate produced a 1,3-thiazine from cinnamoyl isothiocyanate. The mechanisms of the reactions are discussed briefly. The thiones readily form adducts with methyl iodide and reactive acetylenes. In the latter case, 1,3-dithiole derivatives are obtained.
Stereochemistry of the silylcarbinol to silyl ether rearrangement
Authors: Brook A. G. , Warner C. M. , Limburg W. W.
Published: May 2006

It is shown that optically active methyl-α-naphthylphenylsilyldiphenylcarbinol and optically active methyl- α naphthylphenylsilylmethylphenylcarbinol undergo highly stereo-selective rearrangements to the isomeric silyl ethers. Both rearrangements involve retention of configuration at the asymmetric silicon center. The silylmethylphenylcarbinol is also shown to undergo retention of configuration with complete stereoselectivity at the asymmetric carbon center, regardless of the catalyst or solvent employed. The use of nuclear magnetic resonance for determining the proportions of the diastereomers is described, as are the syntheses of a number of asymmetric silicon compounds.
Optical and geometric isomers of some fatty acids with vicinal hydroxy groups
Authors: Ewing D. F. , Hopkins C. Y.
Published: May 2006

Racemic threo-9,10-dihydroxypalmitic acid was resolved by means of the brucine salts into the optically active forms. Levorotatory threo-11,12-dihydroxyeicosanoic acid was obtained from the corresponding racemate by crystallization of the ephedrine salts.The conformation of the geometric isomers of certain dihydroxy long-chain acids and their derivatives was studied by means of nuclear magnetic resonance spectra. There was a small but significant difference in the chemical shift of the CH protons in the ( ± )-threo acid as compared with those in the ( ± )-erythro acid. This was observed in 9,10-dihydroxypalmitic, 9,10-dihydroxystearic, and 11,12-dihydroxyeicosanoic acids. A similar but larger difference in the chemical shift (0.49 p.p.m.) was observed for the CH protons in the O-isopropylidene derivatives of the same acids. These differences are discussed and correlated with the stereochemistry of the dihydroxy acids and the corresponding 1,3-dioxolanes.cis-( + )-12,13-Epoxyoleic acid was isolated from the seed oil of Vernonia colorata. ( − )-threo-12,13-Dihydroxyoleic acid was prepared from the oil of V. cinerea.
Coordination compounds of 1,3-butadiene with anhydrous silver tetrafluoroborate
Authors: Quinn H. W.
Published: May 2006

Two crystalline complexes of 1,3-butadiene with anhydrous silver tetrafluoroborate have been isolated and shown to have the stoichiometry

[Formula: see text] and

[Formula: see text]. On the basis of their infrared spectra, it has been suggested that in the solid state the 1:1 complex is polymeric in nature with alternating butadiene molecules and AgBF4 units in the chain and that the 2:3 complex is formed by bridging of butadiene molecules between silver ions in adjacent chains.
Infrared spectra of KH2F3 and the structure of the H2F3− ion
Authors: Ažman A. , Ocvirk A. , Hadži D. , Giguère Paul A. , Schneider Michel
Published: May 2006

The infrared absorption of KH2F3 and KD2F3in the solid state was measured between 4 000 and 200 cm−1 The observed bands can be assigned to the stretching and bending modes of the bent H2F3− ion. A normal coordinate analysis was carried out to determine the Urey–Bradley force constants. The results suggest that the hydrogen atoms are not exactly halfway between two fluorine atoms, contrary to the case of the HF2− ion.Les spectres infrarouges de KH2F3 et KD2F3 à l'état solide ont été mesurés entre 4 000 et 200 cm−1 afin d'identifier les vibrations fondamentales de l'anion H2F3−. Les constantes de forces de rappel selon le modèle de Urey–Bradley ont pu être déterminées par analyse des coordonnées normales. Les résultats indiquent que les atomes d'hydrogène ne sont pas exactement à mi-chemin entre deux atomes de fluor, contrairement au cas de l'ion HF2−.
Nuclear recoil reactions in organomanganese compounds. II. Methylcyclopentadienylmanganese tricarbonyl
Authors: Yang I. C. , Wiles D. R.
Published: May 2006

The study of nuclear recoil reactions in organomanganese compounds was continued in methylcyclopentadienylmanganese tricarbonyl, a liquid, following earlier conclusions that the recombination reactions may involve a radical diffusion mechanism. Only a very small annealing effect was observed, but that was similar to the earlier results in which a maximum organic yield is reached, followed by a return to the initial value. Results of irradiation in benzene solution show no decrease of organic yield on dilution, which is interpreted as indicating that ‘hot’ reactions do not play a major role. Results of irradiation in mixed benzene–acetone solutions show a sharp decrease in organic yield as small quantities of acetone are added, which suggests a radical-scavenging process. The observation made earlier that considerable CH3Mn(CO)5is produced in this reaction leads to the speculation that radicals of the form Mn(CO)xare the reacting species.
Photolyse de l'iodure de vinyle pur et en solution dans le tétrachlorure de carbone. II. Rendements quantiques
Authors: Roberge Pierre C. , Herman Jan A.
Published: May 2006

The quantum yields of acetylene and molecular iodine from the photolysis of pure vinyl iodide are 0.22 and 0.07 respectively. The disproportionation/recombination ratio for vinyl radicals with iodine atoms in diffusion-controlled processes is 0.34, as established from the quantum yields. A reaction scheme is proposed and several ratios of rate constants are calculated.
Reactions of thiyl radicals. II. The photolysis of methyl disulfide vapor
Authors: Rao P. M. , Copeck J. A. , Knight A. R.
Published: May 2006

The photolysis of methyl disulfide vapor in the pressure range 2–25 Torr at wavelengths between 2 300 and 2 800 and at 2 288 Å has been examined and the effect of temperature, pressure, added inert gases, ethyl disulfide, and nitric oxide determined.The primary process is a direct production of two CH3S radicals which have excess energy and which can be observed as methyl thionitrite when NO is present during the decomposition. When pure disulfide is photolyzed the major observable product is methanethiol, although this material accounts for only a small fraction of the primarily produced thiyl radicals whose principal fate is recombination in a substrate-reforming reaction producing excited disulfide molecules. The latter species are deactivated by added gases, or by the substrate itself. The mode of mercaptan formation is by abstraction of H atoms from the substrate by excited CH3S radicals with an apparent activation energy of 1.5 kcal.
Reactions of phenyl-substituted heterocyclic compounds. VII. Reagent-dependent orientation in the nitration of 4-phenylpyrimidine
Authors: Lynch Brian M. , Poon Lizzie
Published: May 2006

In the nitration of 4-phenylpyrimidine, the nature of the reaction products is strongly dependent upon the nitrating reagent. Mixed nitric and sulfuric acids yield 4-o- and 4-m-nitrophenylpyrimidines in the ratio 2:3, whereas nitric acid – trifluoroacetic anhydride yields 4-o-, 4-m-, and 4-p-nitrophenylpyrimidines in the ratio 45:29:26, and nitric acid – acetic anhydride yields 2,4-diacetoxy-1,3,5-trinitro-6-phenyl-1,2,3,4-tetrahydropyrimidine.An explanation of these findings involves the possibility of the addition of nitronium ion at the heterocyclic nitrogen, followed in some circumstances by nucleophilic addition.
Synthesis of 2′-(N′-bis(2-chloroethyl)glycyltryptophyl)emetine and related peptides
Authors: Pettit George R. , Gupta S. K.
Published: May 2006

Synthesis of the alkaloidal peptides corresponding to structures Ib–Il has been studied. Of several peptide bond forming techniques, the mixed carbonic anhydride and 1-ethyl-3-(3′-dimethylaminopropyl)carbodiimide methods proved generally useful. The potential utility of emetine as a means of transporting N-bis(2-chloroethyl)glycine is discussed.