bluuebunny/crossref_metadata_2025 huggingface dataset:
A Convenient Synthesis of Monobromogermane
Authors: Anderson J. W. , Barker G. K. , Drake J. E. , Hemmings R. T.
Published: May 2006

Monobromogermane, GeH3Br, is conveniently prepared by the reaction of boron tribromide with germane.
Circular Dichroism of Nitrate Esters: A Planar Symmetry Rule for the Nitrato Chromophore
Authors: Barton R. E. , Hayward L. D.
Published: May 2006

Conformational analysis of nitrate esters based on X-ray and spectroscopic data showed the nitrato group to be coplanar with the α carbon atom and, in the preferred rotamer, the nitro moiety to be antiperiplanar to the β carbon atom. Three optically active absorption bands not apparent in the isotropic electronic spectra were resolved in the circular dichroism spectra. Band I (270 nm) reflected nitrato group libration changing sign and magnitude with changes in temperature and solvent polarity. Differences in rotatory strength of band III (210 nm) for cis- and trans-dinitrates indicated transition moment coupling. A planar symmetry rule for chromophores in the Cs point group correlated the molecular geometry and sign of band II for 42 nitrate esters: when the lowest-energy rotamer of the nitrate ester is viewed down the O—C bond with the nitro group uppermost rotatory contributions to band II (230 nm) are positive for perturbing atoms to the right and negative for those to the left of the nitrato symmetry plane.
Synthesis of 1-Methyl-tricyclo[5.2.2.02,6]undec-2(6)-ene-8-one
Authors: Mercier C. , Addas A. R. , Deslongchamps P.
Published: May 2006

Synthesis of the tricyclic ketone 1 is reported.
Les équilibres solide–liquide dans des systèmes binaires formiate d'alcalin-formiate d'alcalino-terreux
Authors: Berchiesi G. , Cingolani A. , Leonesi D. , Piantoni G.
Published: May 2006

The liquid–solid equilibrium temperatures of the (HCOOMe)2 + (HCOO)2Me′ (where Me = Na, K, Tl; Me′ = Mg, Ca, Sr, Ba) binary systems were determined. The deviations from the ideal curve T = ΔHfus/(ΔSfus − R ln x) are explained by the polarization effect of the ions.
Photosensitization by Cd(3P1) Atoms. II. Gas Phase Decomposition of Cyclohexane
Authors: Kalra B. L. , Knight A. R.
Published: May 2006

The photodecomposition of cyclohexane sensitized by Cd(3P1) atoms has been studied in the vapor phase at 355 °C. The primary decomposition gives hydrogen atoms and cyclohexyl radicals. The volatile products of the decomposition are H2, cyclohexene, propylene, ethane, ethylene, methane, propane, butadiene, and methylcyclopentane. Products other than H2 and cyclo-C6H10 arise from unimolecular reactions of cyclohexyl radicals, the most important such process being the production of propylene and allyl radicals. Hydrogen yields decrease rapidly with time because of H-atom scavenging reactions involving olefinic products. The quantum yield of molecular hydrogen formation at the shortest exposure time examined is 0.53.
The Photolysis of Benzoic Acid in the Vapor Phase
Authors: Chau Francis , Gibbons Cyril , Barton Donald
Published: May 2006

The photolysis of benzoic acid in the vapor phase has been investigated in a flow system at temperatures ranging from 110–305 °C, pressures from 0.06–1.73 Torr, and at various incident light intensities. Carbon dioxide and benzene are the main products and carbon monoxide is a minor product. The rate of formation of carbon dioxide is proportional to the first power of the light intensity and is independent of benzoic acid concentration at pressures from 0.29–1.73 Torr. The activation energy for carbon dioxide formation is approximately 3 kcal per mol. A radical chain mechanism has been suggested, in which initiation results from decomposition of vibrationally excited ground state benzoic acid molecules, and termination occurs at the wall. A molecular mechanism is a possibility if the rate of formation of vibrationally excited ground state is a function of temperature.
Dielectric Relaxation of Bromoalkanes in Cyclohexane Solution
Authors: Tay Sing Pin , Crossley John
Published: May 2006

Mean relaxation times, Cole–Cole distribution parameters and apparent dipole moments, obtained from dielectric constant and loss measurements at 2 MHz and 1.5, 2.0, 2.5, 9.3, 16, 24, 35, 70, and 145 GHz, are reported for 1-, 2-, and 4-bromooctane, 1-bromodecane, 1-bromododecane, 1-bromohexadecane, 1-bromooctadecane, and 1,10-dibromodecane in cyclohexane solution at 25 °C.
13C Chemical Shifts of Highly Substituted Bicyclo[2.2.1]heptanes
Authors: Werstiuk N. H. , Taillefer R. , Bell R. A. , Sayer B. G.
Published: May 2006

The 13C chemical shifts have been determined for a series of highly substituted norbornanes. A comparison of the observed values with the expected chemical shifts, determined as described by Lippmaa, establishes that 13C shifts may be predicted reasonably accurately even in highly substituted norbornyl systems. Since substituted norbornanes definitely exist in synchro or contra twist forms as shown by Altona, the results show that Lippmaa's substituted shift parameters must already account for the major part of the increments that arise via hybridization changes resulting from the distortion of the [2.2.1]-skeleton.
Acid-catalyzed Ring Opening of Halo-nortricyclanes
Authors: Cappelli Frank P. , Timmins George , Werstiuk Nick H.
Published: May 2006

The acid-catalyzed (CH3COOH–0.1 M H2SO4) opening of the cyclopropyl ring in nortricyclyl chloride and nortricyclyl bromide gives in each case the anti-7-, syn-7-, exo-5-, and endo-5-halo-exo-2-norbornyl acetates as the major products. When the reactions are carried out in deuterated medium the deuterium is situated endo at C-6 in the anti- and syn-7- haloacetates and establishes that at least 75% of the products arise from initialedgeprotonation of the cyclopropane.
Base-catalyzed Degradations of Carbohydrates. II. β-Elimination Reactions of 4-O-Substituted Methyl (Methyl 2,3-Di-O-methyl-β-D-glucopyranosid)uronates
Authors: Aspinall G. O. , Barron P. E.
Published: May 2006

The action of various bases on the three hexuronic esters, methyl (methyl 2,3,4-tri-O-methyl-β-D-glucopyranosid)uronate (12), methyl (methyl 4-O-methanesulfonyl-2,3-di-O-methyl-β-D-glucopyranosid)uronate (13), and methyl (methyl 4-O-acetyl-2,3-di-O-methyl-β-D-glucopyranosid)uronate (14), leading to elimination of the 4-O-substituents and formation of methyl (methyl 4-deoxy-2,3-di-O-methyl-α-L-threo-hex-4-enopyranosid)uronate (15) has been studied. It is concluded that effectiveness of 4-O-substituents as leaving groups is in the sequence, methanesulfonyloxy > acetoxy > methoxy.
Matrix Infrared and Raman Spectroscopic Evidence for Pd(N2)3 in Solid Nitrogen
Authors: Ozin G. A. , Moskovits M. , Kùndig P. , Huber H.
Published: May 2006

Cocondensation of palladium atoms with 14N2 at 4.2–10 °K leads to the formation of a binary dinitrogen complex. The complex is detected by matrix isolation infrared and Raman spectroscopy. Isotope studies using equimolar 14N2/15N2 mixtures, together with isotope frequency and integrated absorption intensity calculations, suggest that the species is tris-dinitrogen palladium(0), Pd(N2)3.
Reaction of N-Methyl-4-(2′-octoxy)pyridinium Iodide with Silver Oxide. Evidence for a Mechanism Involving a Pseudobase Intermediate
Authors: Schmid G. H. , Wolkoff A. W.
Published: May 2006

The reaction of optically active N-methyl-4-(2′-octoxy)pyridinium iodide with silver oxide results in the formation of optically active 2-octanol with 91% retention of configuration. A mechanism involving a pseudobase intermediate is consistent with this result.
Surface Studies of Heat-treated γ-Aluminas in the Adsorption of Sulfur Dioxide below Monolayer Coverage
Authors: Glass R. W. , Ross R. A.
Published: May 2006

Calorimetric heats of adsorption of sulfur dioxide at surface coverages from 0.1 to 3.5 µmol m−2 have been measured on a series of γ-aluminas heat-treated at 500, 700, and 900 °C. Essential features of the structures of the adsorbents have been characterized by analysis of nitrogen adsorption/desorption isotherms and by both direct and indirect electron microscopy.Heats of adsorption of 423 °K for adsorbed amounts of 0.1 µmol m−2 were 48.0, 59.0, and 85.0 kcal mol−1 for the 500, 700 and 900 °C samples, respectively. The values for the 500 and 700 °C samples fell rapidly with increasing coverage to around 19.0 kcal mol−1 at 3.2 to 3.3 µmol m−2, while the values for the 900 °C sample decreased slowly to 15.0 kcal mol−1 at the same coverage.The pores had circular cross sections and mean diameters of 25, 35, and 40 Å were observed for the 500, 700, and 900 °C samples, respectively. Examination of carbon/platinum replicas of the surface showed the presence of agglomerates of spherical particles approximately 400 Å in diameter.It is proposed that the high initial heats on the 500 and 700 °C samples are due to the formation of a sulfate-like species on the surface and at higher coverage extensive hydrogen bonding is present. The very high heats obtained on the 900 °C sample are believed to be due to interactions with high-energy defect centers in the oxide which were created by heat treatment.
Biosynthesis of Lycopodine. Pelletierine as an Obligatory Intermediate
Authors: Braekman J.-C. , Gupta R. N. , MacLean D. B. , Spenser I. D.
Published: May 2006

The distribution of 14C within lycopodine derived from [1,5-14C]-cadaverine and from [2-14C]-Δ1 -piperideine is profoundly affected by the addition of inactive pelletierine. This finding is interpreted as showing that pelletierine is an obligatory intermediate on the pathway from cadaverine and Δ1-piperideine into lycopodine.
Comparison between Molecular Structure Effects in Triplet Positronium Annihilation Rates and Radiolysis Free Ion Yields in Liquid Hydrocarbons
Authors: Freeman G. R. , Dodelet J.-P.
Published: May 2006

Two seemingly unrelated phenomena in liquid hydrocarbons have similar trends in their dependences upon the molecular structure of the hydrocarbon. The phenomena are the annihilation half-life of triplet positronium and the radiolysis free ion yield. In n-alkanes the effect of increasing the molecular chain length, upon both phenomena, appears to be simply to increase the density of interacting sites. Branching the alkane chain decreases the strength of molecular interaction with both electrons and positronium, although the relative decrease is much greater for the former than for the latter. The effects of double bonds on the phenomena, after separating out the density effect, are different from each other.
Mechanistic Information on the Aquations of Complexes of the Pentaamminecobalt(III) Series from Kinetic Studies at High Pressures
Authors: Jones W. E. , Carey L. R. , Swaddle T. W.
Published: May 2006

The logarithm of the pseudo-first-order rate coefficient k for the aquation of Co(NH3)5X(3–n)+ can be represented by a quadratic equation in the pressure P, or, better, by[Formula: see text]where P is in kbar, [Formula: see text] is the volume of activation at P = 0, and x is the increase in the number of water molecules solvating the complex as it goes to the transition state. For [Formula: see text]Cl−, Br−,[Formula: see text] and [Formula: see text] at 25° [Formula: see text] and ionic strength I = 0.1 M LiClO4/HClO4, [Formula: see text] −10.6, −9.2, −6.3, and +16.8 cm3 mol−1, and x = 8.0, 4.1, 3.9, 1.9, and −4.2; for Xn− = NCS−, the mean ΔV* from P = 0.001 to 2.5 kbar at 88° is −4 cm3 mol−1. Detailed consideration of these data, especially their correlation with the molar volume of reaction by a straight line of unit slope for [Formula: see text] Cl−, Br−, NO3−, and H2O, provides strong evidence for a dissociative interchange mechanism. For [Formula: see text] the separating entity is probably HN3 rather than [Formula: see text] For Xn− = NCS−, aquation is incomplete, at practical complex concentrations; at 88.0°, 1 bar, and I = 0.1 M LiClO4/HClO4, k = 3.3 × 10−6 s−1 and the stability constant of Co(NH3)5NCS2+ is 490 M−1.
A Curious Synthesis of some μ4-Oxo-hexa-μ-halotetracopper(II) Complexes
Authors: Carr B. , Harrod J. F.
Published: May 2006

The thermal decomposition of a series of phenoxo complexes of copper (II), in solution, containing either trichlorophenoxo or tribromophenoxo ligands and a variety of neutral ligands, has led to a rather unique method for the synthesis of μ4-oxo-hexa-μ-halotetracopper(II) complexes. The yield of this complex was found to increase considerably with the ability of the solvent to autoxidize, and also with the addition of hydroperoxides.
Determination of the Heat of Formation of Hexafluorobenzene
Authors: Krech M. , Price S. J. W. , Yared W. F.
Published: May 2006

A new method has been developed for determining the heat of combustion of perfluoro aromatic compounds. The basic differences from previous methods are that no auxiliary substance is used and no water is present in the bomb. The combustion of hexafluorobenzene in a platinum lined bomb yields CO2, CF4, and F2. Visual inspection and the material balance indicate that complete combustion is obtained. The value of [Formula: see text] obtained by this method is −224.0 ± 2.0 kcal/mol. Recalculation of the result of Cox etal. (1, 2) obtained from combustion of C6F6 in mylar bags in the presence of hydrocarbon oil and water leads to[Formula: see text]
The Synthesis of (±)-Ochrobirine. A New Route to the Spirobenzylisoquinoline System
Authors: Cundasawmy N. E. , MacLean D. B.
Published: May 2006

The spirobenzylisoquinoline system has been synthesized from substituted 2-phenyl-1,3-indandiones as starting materials. Ring B of the spiro system was constructed by a modified Pomeranz–Fritsch reaction. The reaction sequence has been applied to the synthesis of an analog of ochrobirine and then to (±)-ochrobirine itself.
Benzene Complexes of Ruthenium(II)
Authors: Zelonka R. A. , Baird M. C.
Published: May 2006

The complexes [π-C6H6RuX2]2 (X = Cl, Br, I, SCN) have been prepared and characterized. They react with phosphorus donors to give the monomeric π-C6H6RuX2PR3, and with cyanide and hydride ions to give cyclohexadienyl and cyclohexadiene complexes.
Electrical Conductivity of Pure and Doped Ammonium Perchlorate Crystals
Authors: Jacobs P. W. M. , Lovatt Frances E. , Ng Wee Lam
Published: May 2006

The conductivity of single crystals of pure ammonium perchlorate and of ammonium perchlorate doped with Ba2+ and with [Formula: see text]ions has been measured at a frequency of 1591 Hz between room temperature and 260 °C. All three systems display a marked increase in conductivity at the temperature of the orthorhombic → cubic phase transition. It is suggested that this sudden increase in conductivity is more probably due to secondary effects (specifically, dislocation generation) than to the actual change in crystal structure. The general similarity between the results for pure and doped crystals tends to support a proton transfer mechanism for a.c. conductivity that does not involve vacancies. However, vacancies may be important in d.c. conductance mechanisms.
Oxidation of Semicarbazones of Ketones. Improved Synthesis of Δ3-1,3,4-Oxadiazolin-2-ones
Authors: Knittel P. , Lee S. L. , Warkentin J.
Published: May 2006

Oxidation of readily-available semicarbazones of ketones with lead tetraacetate, followed by hydrolysis (insitu) of the products, makes novel Δ3-1,3,4-oxadiazolin-2-ones easily accessible. Spectra of the compounds are discussed and some of their potential for synthesis is indicated.
The Pyrolysis of some Neopentyl Xanthates: a Competitive Formation of Olefins and Dithiolcarbonates
Authors: Rutherford K. G. , Tang B. K. , Lam L. K. M. , Fung D. P. C.
Published: May 2006

A study of the pyrolysis of a series of neopentyl-type xanthate esters was carried out at 250 °C. The formation of olefins and dithiolcarbonates were found to be two competing processes. The olefin formation process became more important when the number of β-phenyl groups increased and when there was an electron donating group substituted at the para-position of the β-phenyl ring. Kinetics studies supported the proposal that the transition state of the olefin formation process involved a stabilized phenonium ion. However the dithiolcarbonate formation became more important when there was the least number of β-phenyl substituents and this rearrangement appeared to proceed through a concerted four-membered cyclic transition state.
A Kinetic and Electron Spin Resonance Study of the Polymerization of Vinyl Acetate Retarded by 2,4,6-Tri-t-butylphenol
Authors: Lilles H. , Parnell R. D. , Russell K. E.
Published: May 2006

The effect of 2,4,6-tri-t-butylphenol on the rate of polymerization of vinyl acetate and on the degree of polymerization of the resultant polymer has been determined. It is shown that the phenoxy radicals produced by hydrogen transfer do not reinitiate polymerization and that they disappear from solution by reaction with polyvinyl acetate radicals. The chain transfer constant is estimated to be 0.017 ± 0.004 at 45° from molecular weight studies and 0.021 ± 0.004 from rate studies. Stationary state concentrations of phenoxyl of the order of 10−7 M have been determined by e.s.r. spectroscopy. The rate constant for the reaction of polyvinyl acetate radicals with 2,4,6-tri-t-butylphenoxyl is (6.6 ± 2.3) × 107 l mol−1 s−1 at 45°.
Charge-transfer Complexes with Nitrate Esters as Electron Acceptors
Authors: Urbański T. , Hetnarski B. , Południkiewicz W.
Published: May 2006

Nitrate esters of alcohols, containing from one to six O-nitro groups, react with tetramethyl-p-phenylenediamine (TMPD) in non-polar solvents to yield Wurster cation. The number of O-nitro groups necessary to produce 1 mol of Wurster cation is at least three. This is now explained in terms of the enthalpy of the reaction related to the electron affinity of nitrate esters; esters with five to six O-nitro groups show a relatively high enthalpy manifested by their ability to form charge-transfer complexes. Initially an unstable complex A is formed which then gives Wurster cation, both reactions being fast. A slow transformation then occurs into more stable complex B having the composition: 1 mol TMPD–2 mol of pentanitrates or 1 mol TMPD–1 mol of hexanitrate. TMPD in complex B was transformed into tetramethyl-p-quinonediimine dication.That all nitrate esters with one to four O-nitro groups do not form complexes A and B may be due either to their relatively low enthalpy (and electron affinity), or to more favorable structures of complexes A and B of pentanitrates of D-xylitol and penta- and hexanitrates of hexitols with TMPD.
Partial Photoresolution of Some Chromium (III) Complexes of Phenanthroline and Bipyridine Using Circularly Polarized Laser Irradiation
Authors: Kane-Maguire Noel A. P. , Langford Cooper H.
Published: May 2006

Partial photoresolution of [Formula: see text], Cr(C2O4)2phen−, and [Formula: see text] by irradiation with circularly polarized light from an argon ion laser and 496.5 or 514.5 nm is reported. Steady states corresponding to 1–2% resolution are achieved. They are in agreement with predictions from known circular dichroism and the assumption that differential isomerization is simply a consequence of differential absorptivity of the enantiomers.
Infrared Spectra and Structures of Solid CH4 and CD4 in Phases I and II
Authors: Chapados C. , Cabana A.
Published: May 2006

This paper reports the results of extensive infrared absorption measurements of CH4, CD4, and mixed isotopic crystals containing CH4, CD4, CHD3, and CH3D at low concentration in matrices of light and heavy methane in crystalline phases I and II. The interpretation of the spectra, based upon the Halford–Hornig approach, provides information on the crystal structures. The spectra indicate that the two solid phases of CH4 are similar to the two higher temperature phases of CD4. In phase I, there is apparently considerable motion: either the molecules undergo large angular oscillations or even rotational diffusion. In phase II, there exist two types of sites for the molecules: some molecules undergo quantized rotation similar to that found in noble gas matrices while others order with a local symmetry that is probably slightly distorted from Td[Formula: see text] to D2d[Formula: see text]. Acceptable factor groups are then limited to Td and Oh, but the former is unlikely for it could yield the f.c.c. lattice found by diffraction experiments only by a particular choice of the parameters, whereas the latter leads to the f.c.c. space group [Formula: see text] (Fm 3c).
The Transformations of Dimeric Tri-O-acetyl-2-deoxy-2-nitroso-α-D-hexopyranosyl Chlorides in Dimethylformamide
Authors: Lemieux R. U. , Nagabhushan T. L. , James K.
Published: May 2006

The dimeric nitrosyl chloride adducts of tri-O-acetyl-1,5-anhydro-2-deoxy-D-arabino-hex-1- and D-lyxo-hex-1- enitols (glycals) dissociate in dimethylformamide to the monomeric forms which rapidly isomerize to the corresponding tri-O-acetyl-2-oximino-α-D-hexopyranosyl chlorides. Evidence is provided for the dehydrochlorination of these latter compounds to highly reactive tri-O-acetyl-1,5-anhydro-2-deoxy-2-nitroso-D-hex-1-enitols.
Termolecular Recombination Rate Constant and Triple Collision Cross-section
Authors: Wong W. H. , Burns G.
Published: May 2006

The concept of triple collisions cross-section in termolecular recombination reaction was investigated. The hard-sphere model was tested against experimental data, and it was found to predict, in disagreement with experiments, a positive temperature dependence for the recombination rate constants. Average cross-sections were obtained from experimental rate data. Two empirical functions widely used for summarizing experimental rate data were inverted through an inverse Laplace transform to give the triple collision cross-section.
Further N.M.R. Studies of the Dynamic Stereochemistry of π-Allylic Palladium(II) – Tertiary Phosphine Systems
Authors: Oslinger M. , Powell J.
Published: May 2006

A series of cations of the type 1,2-bis(diphenylphosphino)ethane(π-all)palladium(II) (all = allyl, 2-methylallyl, 2-tert-butylallyl, 1-methylallyl, 1,1-dimethylallyl, syn-1-tert-butyl-2-methylallyl) have been isolated as PF6− and/or BF4− salts. Variable temperature n.m.r. data fully substantiate the proposal that pyridine promoted exchange of syn and anti proton sites in such complexes occurs via a π → σ → π mechanism that involves consecutive SN2 ligand substitutions. Comparison of this variable temperature n.m.r. data with that obtained for the complexes 1,2-bis(diphenylphosphino)ethane(π-all)palladium(II) chloride (prepared in situ) has shown that the chloride ion, functioning as a nucleophile, is also effective in promoting π → σ → π reactions. Studies of bis(dimethylphenylphosphine) (π-1,1-dimethylallyl)palladium(II) chloride in CDCl3 below −30° have shown that rapid consecutive SN2 substitution reactions, in which chloride acts as a nucleophile, are also occurring in systems containing monodentate tertiary phosphine ligands. As such the PR3 promoted syn–syn and anti–anti proton site interchange observed in complexes of the type [(π-2-methylallyl)PdCl(PR3)] has been reinterpreted in terms of consecutive ligand substitution reactions involving PR3 and Cl ligands instead of the original proposal which involved an in plane rotation of the π-allylic ligand.
The Vibrational Spectra and Crystal Structure of Acenaphthylene
Authors: Bree A. , Kydd R. A. , Vilkos V. V. B. , Williams R. S.
Published: May 2006

A study of the polarized infrared and Raman spectra of acenaphthylene single crystals has been made. These results, together with Gordon and Yang's preliminary X-ray work, suggest that the molecules pack in some disordered arrangement in the solid at room temperature. Most of the A1 fundamentals were identified in the Raman solution spectrum from their low depolarization ratio, and a few tentative assignments of nontotally symmetric fundamentals were made.
Synthesis of Some Epiminocyclohexanes by Hydride Reduction of α,β-Unsaturated Cyclohexanone Oximes and the Pyrolytic cis-Elimination of N-Acetylepiminocyclohexanes
Authors: Dimmock J. R. , Turner W. A. , Smith P. J. , Sutherland R. G.
Published: May 2006

Reduction of several 2-benzylidenecyclohexanone oximes with lithium aluminum hydride gave the corresponding 1-benzyl-1,2-epiminocyclohexanes. Reduction of 2-benzylidenecyclohexanone oxime with lithium aluminum deuteride gave an epiminocyclohexane (8) which had incorporated two deuterium atoms. A reaction mechanism for the reduction is postulated. The major fragmentation pathways in the mass spectrum of 8 are outlined. Acetylation of 1-benzyl-1,2-epiminocyclohexane with acetic anhydride (15 min reflux) gave 3-acetamido-2-benzyl-1-cyclohexene by a pyrolytic cis elimination.
The Photochemical Decomposition of Gaseous Formaldehyde
Authors: Sperling Henry P. , Toby Sidney
Published: May 2006

The photolysis of formaldehyde was studied at 313, 334, and 366 nm in the range 80–120° and 9–40 Torr, over a 300-fold range of incident intensity. Some heterogeneous thermal decomposition was noted at these temperatures. It was found that [Formula: see text] and ΦCO were independent of intensity at low intensities which suggests that CHO → CO + H was unimportant in our system. From the zero-intensity extrapolations of Φ it was possible to obtain [Formula: see text] for CH2O + hv → H + CHO and [Formula: see text] for CH2O + hv → H2 + CO. [Formula: see text] and [Formula: see text] were found to vary considerably with wavelength and the values obtained are compared with literature data.
Naphthyridine Chemistry. XVII: Di-N-alkylated Naphthyridines
Authors: Pokorny David J. , Paudler William W.
Published: May 2006

It has been shown that the N,N′-dimethylated naphthyridines form pseudo bases by hydroxide addition in the quinolinoid rather than the isoquinolinoid ring, where possible.The charge repulsion in the 1,8-dimethyl-1,8-naphthyridinium ion is reflected by its facile partial conversion to a mono-pseudo base at room temperature. A variable temperature study of this equilibrium reaction is described.
The Interactions of Four Carbamate Pesticides with Electron-acceptor Reagents
Authors: MacNeil James Daniel , Frei Roland Walter , Hutzinger Otto
Published: May 2006

The interactions between several electron-acceptor reagents and some pesticides having donor properties were investigated in solution and on cellulose thin-layers by spectrophotometric methods. In solution, formation constants and extinction coefficients were evaluated from absorbance measurements for complexes of the pesticides carbaryl, IPC, CIPC, and swep with the electron-acceptor reagent 9-dicyanomethylene-2,4,7-trinitrofluorene, using the Benesi–Hildebrand method. Values were also calculated for the carbaryl-mellitic trianhydride complex. Extinction coefficients [Formula: see text] for the complexes were less than 1000, while formation constants were 1–41 mol−1Reflectance spectroscopic measurements showed similar relationships between absorption maxima and intensities of the complexes and the donor properties of the pesticides to those observed in solution. A linear relationship between reflectance and the square root of concentration was found for all four pesticide–CNTNF complexes in the range from 5–50 µg.
The Preparation and Properties of Some Cyclic β-Diketone Diimines
Authors: Moss Kenneth Charles , Robinson Frank Price
Published: May 2006

The condensation reaction between a series of aliphatic diamines and a series of five- and six-membered cyclic β-diketones to form Schiff bases was investigated. Mass spectral data show that reaction occurred on the side-chain carbonyl except where steric hindrance forced condensation to occur on the ring carbonyl. N.m.r. studies show that these Schiff bases exist primarily in the ketamine form in solution, irrespective of the solvent. I.r. data confirm this. The preparation of a number of Cu(II) and Ni(II) complexes from some of the ligands is also described.
Isotopic Studies of the Metal–Ligand Bond. Part II. The Far Infrared Spectra of Some Binuclear and Polymeric Copper Carboxylate Derivatives; Variable Temperature and Isotopic Studies of the Copper–Ligand Vibrations
Authors: Lever A. B. P. , Ramaswamy B. S.
Published: May 2006

The far infrared spectra of 16 adducts of pyridine, quinoline, isoquinoline, urea, aniline, o- and p-toluidine with copper acetate, propionate, and butyrate, and of copper formate tetrahydrate were recorded at ambient temperature and at −196 °C. A range of derivatives were prepared containing isotopically pure 65Cu. The spectra of these derivatives were used to identify, unequivocally, the copper–oxygen stretching frequencies.Complexes believed to be polymeric (aniline and toluidine adducts) exhibit one copper–oxygen stretching vibration between 300 and 350 cm−1 A second band, lying between 350 and 400 cm−1 is not isotopically sensitive. The dimeric complexes exhibit one or two bands in the 300–400 cm−1 region, all of which are isotopically sensitive. Certain of the amine adducts exhibit an isotopically sensitive band near 240 cm−1 assignable to a Cu—N stretching mode.
Studies of Oxygen Exchange Between Trivalent Lanthanide – EDTA Complexes and Solvent Water: Evidence for a Structural Change Within the Series
Authors: Betts R. H. , Voss R. H.
Published: May 2006

Oxygen-18 labelled EDTA, dissolved in normal water, has been used to examine the kinetics of oxygen transfer between the solvent and a variety of metal–EDTA complexes, including most of the lanthanides, Ca and Th. The lability of the oxygens is profoundly affected by the ionic charge of the metal in the chelate. Thus oxygen exchange in the Th–EDTA–H2O system shows a half-life of 10 min at 100 °C, while for comparable conditions, Ca–EDTA–H2O shows a half-life in excess of 100 days. The lanthanides as a group show behavior intermediate between these extremes. Within the latter group the lability varies systematically with atomic number, Pr–EDTA (element 59) being the most reactive and Yb–EDTA (element 70) the least reactive. The maximum variation across the group is about 10-fold. Interpretation of these results is presented in terms of the polarizing effect of the metal ion on the electron density at the acetate groups. The variation in lability within the lanthanide group can be accounted for quantitatively by changes in coordination number of the central metal ion.
Reactions of Hot Hydrogen Atoms in Gaseous Hydrogen Chloride and Hydrogen Bromide
Authors: Jardine D. K. , Ballash N. M. , Armstrong D. A.
Published: May 2006

Hydrogen atoms of initial kinetic energy E0 = 1.15 or 2.1 eV were produced photolytically and their reactions with HCl were studied at 300 °K using bromine as a scavenger. The fraction, FH, undergoing reaction 2 while hot was found to be 0.79 ± 0.02 and 0.55 ± 0.02 for E0 = 2.1 and 1.15 eV, respectively.[Formula: see text]For 2.1 eV atoms a similar result was obtained at 200 °K with chlorine as scavenger. On the addition of carbon dioxide as a moderator FH decreased in a manner consistent with the kinetic theory of hot atom reactions. Comparison of the present results with previous work on the D + DCl abstraction reaction showed that the cross section of the latter is probably 20 to 50% higher than that of H + HCl. The cross section of reaction 2 appears to increase with energy over most of the 0.1 to 1.1 eV range and possibly also above it. Its average magnitude over this energy region was estimated to be [Formula: see text].For atoms of E0 = 1.15 eV reacting in HBr FH is close to unity. The threshold of reaction 3′[Formula: see text]is near zero energy and its cross section rises rapidly, becoming [Formula: see text] in the thermal region for 300 °K.
The Infrared and Raman Spectra of 3,4-Dichloro-1,2,5-thiadiazole
Authors: Richardson A. W.
Published: May 2006

The i.r. and Raman spectra of 3,4-dichloro-1,2,5-thiadiazole have been recorded and assignments made for all 15 fundamental vibrations. Preliminary data from the vapor-phase u.v. absorption spectrum have been used to confirm some assignments.
Bimolecular Reactions of Trapped Ions. V. Ionic Chemistry of Simple Oxygen-containing Molecules
Authors: Blair Alan S. , Harrison Alex. G.
Published: May 2006

The ion-molecule reactions occurring in a number of one-component and two-component systems involving oxygen-containing compounds have been studied using an ion trapping technique. The variable reaction time possible (up to 3.2 ms) has permitted a study of the sequential ion–molecule reactions occurring. In one-component systems (M = CH3CHO, (CH3)2O, or (CH3)2CO) the MH+ ion formed initially reacts to produce M2H+ in a rapid third order reaction (k in the range 10−24 to 10−25 cm6 molecule−2 s−1). No M2H+ was observed in ethylene oxide. In two-component systems a rapid proton transfer reaction M1H+ + M2 → M2H+ + M1 occurs when the proton affinity of M2 is greater than the proton affinity of M1; consequently, the third order solvation reactions normally will involve only reactions of M2H+.The reactions of isomeric C2H5O+ ions have been studied. The CH3OCH2+ ion reacts slowly by H− abstraction and/or CH3+ transfer. The CH3CH=OH+ ion rapidly (and essentially completely) transfers a proton to (CD3)2O and to (CH3)2CO. By contrast the C2H5O+ ion obtained by protonation of ethylene oxide does not react completely with (CD3)2O or (CH3)2CO. In the former case a quasi-equilibrium is reached while in the latter case there is evidence that the C2H5O+ ions have rearranged to a CH3OCH2+ structure by an unknown mechanism.Considerable detail has been obtained concerning the primary ion–molecule reactions occurring, particularly for systems containing ethylene oxide.
Fluorinated Alkoxides Part VII. Complexes of 2-Acetamidohexafluoro-2-propanol with First-row Transition and Lanthanide Elements
Authors: MacDonald Celia , Willis C. J.
Published: May 2006

2-Acetamidohexafluoro-2-propanol (HAcfp), CH3CONHC(CF3)2OH, may act as a bidentate, uninegative, ligand to give complexes of the type M(Acfp)2 (M = Co2+, Ni2+, Cu2+, Zn2+); M(Acfp)3 (M = Fe3+); M(Acfp)4 (M = Ce4+); or [M(Acfp)4]− (M = lanthanide(III)). Coordination is through the two oxygen atoms, except in the case of copper, where nitrogen also enters into coordination. In the complex Cu(Acfp)2, the amido proton may be removed with NaH to give Na2[Cu(Acfp)2], which undergoes addition reactions with carbonyl groups.Formamide similarly undergoes reaction with hexafluoroacetone to give HCONHC(CF3)2OH, which chelates to copper in the same manner as HAcfp, while succinic acid diamide reacts with hexafluoroacetone to give the compound [—CH2CONHC(CF3)2OH]2, which acts as a tetradentate, dinegative, ligand.Possible structures of the above complexes are discussed.
The Chemistry of the Aminochromes. Part XVI. Proton Magnetic Resonance Spectroscopy
Authors: Powell W. S. , Heacock R. A. , Smith D. G. , McInnes A. G.
Published: May 2006

The p.m.r. spectra of a number of aminochromes and aminochrome monosemicarbazones have been measured and the major features of the spectra discussed. The synthesis of a new aminochrome, 2-methylnoradrenochrome is described.
Electrochemical Studies of Organotitanium Nitrogen Fixation Systems
Authors: Chivers T. , Ibrahim E. D.
Published: May 2006

The electrochemical reduction of compounds of the type (π-Cp)2Ti(R)Cl (R = Cl, CH3, C6H5, C5F5, OTiCl(π-Cp)2) in ether solvents has been studied using the techniques of polarography, controlled potential electrolysis, and cyclic voltammetry. The one-electron reduction products, presumably (π-Cp)2TiR (R = CH3, C6F5), are initially green in tetrahydrofuran but, in a dinitrogen or argon atmosphere, they form intensely blue solutions which result from the reaction of (π-Cp)2TiR with tetrahydrofuran solvent.
The New Synthesis of 5,6-Dimethyl-5-hepten-2-one from 2,3-Dimethyl-1,3-butadiene
Authors: Watanabe Shoji , Suga Kyoichi , Fujita Tsutomu
Published: May 2006

The reaction of 2,3-dimethyl-1,3-butadiene (1) with methyl acetoacetate in the presence of a catalyst composed of palladous chloride and p-phenyl-1-phospha-3-methyl-3-cyclopentene gave 3-carbomethoxy-5,6-dimethyl-5-hepten-2-one (2) (1:1 adduct). Alkali decomposition of 2 gave 5,6-dimethyl-5-hepten-2-one (3), which was a key intermediate for the preparation of α-irone. Similarly, isoprene gave a mixture of 5- and 6-methyl-5-hepten-2-one.
Condensation Reactions of 2-Amino-N-acylphenethylamines and 2-Amino-β-acylaminostyrenes
Authors: Chen F. M. F. , Forrest T. P.
Published: May 2006

Molecular sieves have been used to catalyze the condensation reaction of cis-β-(o-acetotoluidino)-2-aminostyrene (4) to yield 2-methyl-3-(o-tolyl)-3H-1,3-benzodiazepine (11). A second major product from the reaction was 2-(o-toluidino)-N-acetylindole (13), an example of the type of compound presumed to be an intermediate in the Fischer indole synthesis. The formation of N-acetylindole from 13 occurred on treatment of 13 with silica or alumina.The trans isomer, 5, and the reduced analog, 6, were unreactive with molecular sieves but 6 could be converted to 4,5-dihydro-2-methyl-3-(o-tolyl)-3H-1,3-benzodiazepine by reaction with phosphorous oxychloride.
INDO Molecular Orbital Calculations of Nuclear Spin–Spin Coupling Constants Over Three Bonds Between 13C and 1H in Some Simple Molecules
Authors: Wasylishen R. , Schaefer T.
Published: May 2006

Molecular orbital calculations, at the INDO level, of the spin–spin coupling constants over three bonds between carbon-13 and protons are reported for a number of simple molecules. In propane the coupling depends on dihedral angle in the Karplus manner. Fluorine substituents cause changes in the computed coupling which are best described as alternating with the number of bonds intervening between the substituent and the coupled nuclei. Finer details of this phenomenon are discussed and calculations on propyllithium are performed. Replacement of a central carbon atom in propane by a heteroatom does not radically alter the computed couplings. The presence of a carbonyl group in the coupling path results in an overestimate of the magnitude of the coupling. In propene the coupling between 13C in position 1 and a methyl proton displays a maximum when the C—H bond of the methyl group lies parallel to the π orbitals. In toluene the coupling to a methyl proton is insensitive to the dihedral angle over half its range, a result of importance to structural studies. Among other molecules under consideration are methylacetylene, propionaldehyde, and the strained bicyclobutane. It is suggested that in certain instances the mean of the predictions from the INDO and CNDO/2 procedures may agree better with experiment than will the prediction from either procedure alone. Calculations on fluorobenzene and 1,2-difluorobenzene suggest that the main experimental trends of the couplings between carbon and protons within the benzene ring are reproduced. Such is perhaps not true for the five-membered heterocycles.
Pulse Radiolysis of Nitric Oxide in Aqueous Solution
Authors: Seddon W. A. , Fletcher J. W. , Sopchyshyn F. C.
Published: May 2006

Transient spectra observed on the pulse radiolysis of aqueous solutions of nitric oxide at pH 7.0 have been assigned to the species NO−, N2O2−, and N3O3−. In acid solution these species are protonated to form the corresponding acids, HNO, HN2O2, and HN3O3. Both the basic and acid forms undergo similar reactions, but at different rates, to form the products of radiolysis N2O and NO2−.[Formula: see text]The basic species decays more slowly than the corresponding acid species but both processes have appreciable activation energies of 15 and 10 kcals/mol, respectively. Computer calculations have been used in conjunction with the experimental data over a wide range of pH and NO concentration to deduce a reaction mechanism consistent with the observed results. Reaction rate constants, acid dissociation constants and extinction coefficients for the various species are presented and compared with earlier work.
Mechanism of Ozonolysis. The Initial Ozonide. Lack of Evidence for "Unified Concept" Involving Staudinger Molozonide
Authors: Bailey Philip S. , , Jr Thomas P. , Fischer Charles M. , Thompson James A.
Published: May 2006

Contrary to previous reports cyclohexanone and pinacolone are not oxidized to the corresponding Baeyer–Villiger oxidation products during ozonolysis of ethylidenecyclohexane in their presence. Addition of propionaldehyde to a solution of the 1,2,3-trioxolane initial ozonide of trans-1,2-di-t-butylethylene resulted in oxidation of the aldehyde to propionic acid and reduction of the 1,2,3-trioxolane to pivaldehyde. Thus, there is no necessity for the four-membered Staudinger molozonide as an ozonolysis intermediate, as recently proposed by Story.
Constituents of Solidago Species. Part IV. Solidagoic Acids A and B, Diterpenoids from Solidago gigantea var. serotina
Authors: Anthonsen T. , Henderson M. S. , Martin A. , Murray R. D. H. , McCrindle R. , McMaster D.
Published: May 2006

Solidagoic acids A and B, two new diterpenoids from Solidago gigantea Ait. var. serotina (Kuntze) Cronqu., are formulated (absolute configuration tentative) as 1a and b on the basis of chemical, spectroscopic, and optical evidence.
A Study of Solvent Effects on the 13C Nuclear Magnetic Resonance Spectra of Cholesterol, Pyridine, And Uridine
Authors: Mantsch H. H. , Smith Ian C. P.
Published: May 2006

The 13C n.m.r. chemical shifts for cholesterol in five solvents are reported. All carbon atoms were subject to solvent effects of varying sign and magnitude. The chemical shifts in the solvent pair dioxane–chloroform 1:1 could be predicted on an additivity basis. Pyridine was studied in 24 solvents; the chemical shifts of all carbons were solvent-dependent. Solvent effects at positions β and γ were correlated, while those at position α bore no simple relation to those of the other carbons. A small isotope effect was noted on comparing the data for H2O and 2H2O. Coupling between 13C and 14N was observed in some cases; its magnitude was solvent-dependent. Uridine was studied in four solvents. While all carbons were subject to solvent-induced shifts, evidence for specific solvent interaction at C-4, -5, -1′, and -2′ was obtained. An appreciable contribution to the relaxation of carbonyl C-2 and -4 from dipole–dipole interaction with the hydrogen on N-3 was observed. Solvent effects can result in scrambling and misassignment of 13C resonances if care is not taken with choice of solvent.
The Solvent Exchange of Co(CH3NH2)5OH23+
Authors: Shaver A. G. , Parris M.
Published: May 2006

The rate constant for entry of 18O from solvent water into Co(CH3NH2)5OH23+ ion was found to be 1.1 × 10−4 s−1 at 24.9 °C. The equilibrium constant for the formation of Co(CH3NH2)5Cl2+ ion was found to be 7.7 M−1. From these data, the competition ratio between chloride ion and water for a hypothetical intermediate Co(CH3NH2)5 was calculated as 2.5, unexpectedly high.
Quenching and Trapping of Lyman-α Fluorescence at Large Optical Depths
Authors: Phillips Leon Francis
Published: May 2006

Trapping times for 121.6 nm hydrogen resonance radiation in atomic hydrogen gas have been determined by a phase shift method. Rate constants for quenching of H atoms in the n = 2 level have been calculated from the measured trapping times together with the slopes of Stern–Volmer plots obtained under steady-state conditions. The results indicated that the trapping times characteristic of fluorescence decay, and of steady-state fluorescence, differed by less than a factor of two. For quenching by O2, Ar, and He, the values of quenching cross sections obtained (all × 10−16 cm2) were 30 ± 8, 0.9 ± 0.4, and 0.4 ± 0.2, respectively.
The Chemical Degradation of a Humic Acid
Authors: Schnitzer Morris , Serra Maria Ines Ortiz de
Published: May 2006

A humic acid (HA) extracted from the A1 horizon of a Brunizem soil was degraded in the unmethylated and methylated form by sequential reaction with oxidants of increasing strength. The HA was first oxidized with alkaline cupric oxide; the products were then further degraded by oxidation with first alkaline KMnO4 and then with H2O2 in alkaline solution. Unmethylated HA was also degraded by Na-amalgam reduction. The degradation products were extracted into organic solvents, methylated, and separated by preparative gas chromatography into relatively pure components which were analyzed by mass spectrometry and micro-i.r. spectrophotometry. A matching of the mass and i.r. spectra and gas chromatographic retention times of the isolated components with those of authentic specimens led to their identification.The experimental data show that the HA contains a relatively easily degradable portion, which comprises guaiacyl and syringyl units and which may be lignin-derived (about 10% of the total weight). This material is degraded by CuO–NaOH oxidation and Na-amalgam reduction. The bulk of the HA structure, however, consists of a more condensed, chemically complex "core", which degrades on more drastic oxidation into complex phenolic and benzenepolycarboxylic acids. It is likely that the "core" originates in part from condensed lignin and in part from products of microbial synthesis. Of the methods investigated, the CuO–NaOH and the KMnO4 oxidation of methylated HA appear most promising for providing information on the chemical structure of the HA.
Cyclizations of Dialdehydes with Nitromethane. XV. Synthesis of Four Stereoisomeric Deoxynitroinositol Monomethyl Ethers
Authors: Kovář Jan , Baer Hans H.
Published: May 2006

Methylation of 1,2:5,6-di-O-isopropylidene-α-D-glucofuranose (1) followed by hydrolysis of the 5,6-ketal group and periodate oxidation gave 1,2-O-isopropylidene-3-O-methyl-α-L-xylo-pentodialdo-1,4-furanose (4). Addition of nitromethane to 4 afforded a mixture of 6-deoxy-1,2-O-isopropylidene-3-O-methyl-6-nitro-α-D-glucofuranose (5) and -β-L-idofuranose (6). Removal of the 1,2-ketal group led to a mixture of 6-deoxy-3-O-methyl-6-nitro-D-glucose (7) and -L-idose (8) from which the crystalline β-anomer of 7 could be isolated. Cyclization of the nitro hexoses by internal Henry reaction furnished four stereoisomeric deoxynitroinositol monomethyl ethers which were obtained in crystalline condition, in part directly and in part via acetone and acetyl derivatives. The scyllo (9), DL-myo-1 (10), muco-3 (14), and epi-3 (16) configurations were assigned to the products by n.m.r. spectroscopy.
The Structure of the Capsular Polysaccharide of Klebsiella K-type 24
Authors: Choy Yuen-Min , Dutton Guy G. S. , Zanlungo Alberto M.
Published: May 2006

Methylation, periodate oxidation, and partial hydrolysis studies on the capsular polysaccharide, and on the carboxyl reduced polymer, of Klebsiella K24 show the structure to consist of a repeating unit[Formula: see text]The anomeric linkages were determined in isolated oligosaccharides by p.m.r. spectroscopy which also showed the presence in the polysaccharide of one O-acetyl group per seven or eight sugar residues. The O-acetyl is tentatively assigned to one of the D-mannose units.
The Synthesis of Specifically Deuterated Anthracenes
Authors: Charlton J. L. , Agagnier R.
Published: May 2006

Synthetic methods for preparation of anthracene-1,2,3,4-d4, 1,4,5,8-d4, 2,3,6,7-d4, 2,3-d2, 1,4-d2, and 9,10-d2 are described.
Thiyl Radical Abstraction. A Mechanism for the Free Radical Substitution Reactions of Pentachlorobenzenesulfenyl Chloride
Authors: Tanner Dennis D. , Wada Naoto , Brownlee Brian G.
Published: May 2006

The substitution reactions of pentachlorobenzenesulfenyl chloride with saturated alkanes were found to proceed by a free radical chain mechanism where the pentachlorobenzenethiyl radical is the predominant chain-carrying species. The selectivity of this radical could be determined by the investigation of the photoinitiated reactions of bispentachlorophenyl disulfide with a number of alkanes.
Thermal Anomaly in the Temperature Dependence of the Energy–Volume Coefficient of Aqueous KCl Solutions
Authors: Lee Ikchoon , Hyne J. B.
Published: May 2006

The temperature dependence of the energy–volume coefficient of pure water and of aqueous potassium chloride solutions as a function of concentration over the temperature range 10–50 °C has been determined by direct measurement of constant volume thermal–pressure coefficient. The results show that a thermal anomaly exists in the energy–volume coefficient of aqueous solution in the temperature range 30–40 °C and becomes more pronounced as the concentration of solute is increased.