bluuebunny/crossref_metadata_2025 huggingface dataset:
Electron impact-induced rearrangements of substituted 1-phenylpropynes
Authors: Safe S. , Jamieson W. D. , Pilgrim W. R. , Wolfe Saul
Published: May 2006

The primary ion mass spectra of the C9H8 isomers indene and 1-phenylpropyne were remarkably similar. Examination of ion and metastable peak intensities and their energy spectrum indicate that their common M-1 (C9H7+) fragment ion has the same structure. The mass spectra of several substituted phenylpropynes were also similar to that of the parent hydrocarbon below mass m/e 115 but showed no substituent or kinetic effect. The mass spectra of 1-phenylpropyne-d3 clearly shows H/D randomization in the molecular ion and linear ion structures are proposed.
Synthesis of 1,2,3,4,7,8,9,10-octahydrodicyclohepta[de,ij]naphthalene
Authors: Fischer A. , Leonard D. R. A. , Happer D. A. R.
Published: May 2006

Benzosuberone (5) has been converted via the tricyclic ketone 3-oxo-1,2,3,7,8,9,10,10a-octahydrocyclohepta[de]naphthalene (7) and the tetracyclic ketone 1-oxo-1,2,3,4,4a,5,6,6a,7,8,9,10-dodecahydrodicyclohepta[de,ij]naphthalene (14) into 1,2,3,4,7,8,9,10-octahydrodicyclohepta [de,ij]naphthalene (16).
The CdO–CdF2 system: X-ray diffractogram, infrared spectrum, and density of CdO•2CdF2
Authors: Ramamurthy P. , Secco E. A.
Published: May 2006

The CdO–CdF2 system has been studied by differential thermal analysis (DTA), X-ray powder diffraction, and infrared spectroscopy.The results show a distinct X-ray diffractogram and infrared spectrum for the CdO–CdF2 mole ratio 1:2, prefused and annealed, suggesting the existence of the compound CdO•2CdF2. The compound undergoes a transformation at 690 °C, characterized by a low heat absorption suggesting an order–disorder phenomenon.
The kinetics of formation of ruthenium(II) nitrogen complexes
Authors: Elson Clive M. , Itzkovitch I. J. , Page John A.
Published: May 2006

The formation of nitrogen monomers by the reaction of Ru(NH3)5(H2O)2+ and cis-Ru(NH3)4(H2O)22+ with N2 has been shown to be first order in N2 and second order overall. The formation of bridging N2 dimers by the reaction of the ruthenium(II) pentaammine and tetraammine with the monomers has been shown to be second order overall.The reactions were studied in a H2SO4–K2SO4 electrolyte pH 3.3, μ = 0.30. The ruthenium(II) species were prepared by controlled potential reduction of known ruthenium(III) species at −0.50 V at a Hg cathode. The reactions of the reduced species with N2 or the monomers were followed spectrophotometrically.The second order rate constant at 25 °C and the activation energy for the substrate Ru(NH3)5(H2O)2+ with the respective nucleophiles are: N2, 8.0 × 10−2 M−1 s−1, 22.0 ± 0.1 kcal/mole; Ru(NH3)5N22+, 3.6 × 10−2 M−1 s−1, 19.9 ± 0.5 kcal/mole; Ru(NH3)4(H2O)N22+, 2.7 × 10−2 M−1 s−1, 20.4 ± 0.8 kcal/mole. For the substrate cis-Ru(NH3)4(H2O)22+ the values are: N2, 1.0 × 10−1 M−1 s−1, 20.4 ± 0.2 kcal/mole; Ru(NH3)5N22+, 6.8 × 10−2 M−1 s−1, 18.2 ± 0.1 kcal/mole; Ru(NH3)4(H2O)N22+, 7.2 × 10−2 M −1 s−1, 17.1 ± 0.2 kcal/mole.
Triethylenetetraamineruthenium(II) complexes containing bridging molecular nitrogen
Authors: Harris R. O. , Wright Miss B. A.
Published: May 2006

Reaction between a reduced solution of cis-[Ru(trien)Br2]Br•2H2O and gaseous nitrogen yields the dimeric species [(trien)RuXN2XRu(trien)]X2 where X = added anion I, Br and trien = triethylene tetraamine. In solution, the halides undergo solvolysis, before bridge splitting occurs, giving the monomeric [Ru(trien)N2H2O]2+ ion. The rate of formation of monomer is pH dependent, being faster in base.
Alkali metal adducts of benzophenone azine. II. The lithium adduct
Authors: MacPherson E. J. , Smith James G.
Published: May 2006

The behavior of benzophenone azine towards lithium has been studied. Unlike sodium and potassium, lithium effected extensive reduction and cleavage of benzophenone azine; the reaction product being benzhydryl amine. By limiting the amount of lithium to 2 g-atoms per mole of azine, the reaction product was shown to be N-lithiobenzophenone imine on the basis of its chemical behavior.Two reasons are advanced to explain the behavior of lithium in contrast to that of sodium or potassium. One explanation relies upon the greater reducing power of lithium compared with the other two alkali metals. The other relies upon the tendency of organolithium compounds to associate via formation of multi-center bonds.
Radical cations of some substituted pyrenes
Authors: Cooper J. T.
Published: May 2006

The electron spin resonance spectra of several substituted pyrene cations, produced by oxidation with boron trifluoride in sulfur dioxide, are reported. The spectra are analyzed and the splitting constants given. With 4-chloropyrene, hyperfine splitting is observed due to the chlorine atom, for the first time in such a species. Molecular orbital calculations (Hückel and McLachlan) are presented for three of the compounds studied.
Osmotic coefficients of benzenesulfonic acid solutions at 25 °C
Authors: Marcinkowsky A. E.
Published: May 2006

Osmotic coefficients of aqueous benzenesulfonic acid solutions from 0.5 to 16 m are reported. These results compare well with available literature data over the limited concentration interval 0.5 to 5 m. A correlation between the osmotic coefficients and the organic content for benzenesulfonic acid and four substituted aromatic monosulfonic acid solutions at corresponding concentrations above 4 m is shown.
Conditions for the electrochemical formation of Ag2O3 on silver in aqueous KOH solutions
Authors: Barradas R. G. , McDonnell D. B.
Published: May 2006

New evidence is presented to substantiate the electrochemical formation, at certain temperatures, of Ag2O3 as a reasonably stable species under galvanostatic conditions in aqueous KOH electrolytes saturated with Ag2O and O2. The experimental data offer a better understanding of the nature of the Ag2O/AgO transition peak.
Kinetic study of addition of nitrogen and phosphorus donors bis(maleonitriledithiolate)cobalt(III)
Authors: Tsiang Hon. Gee. , Langford C. H.
Published: May 2006

Kinetics of adduct formation of the dimeric form of bis(maleonitriledithiolate)cobalt(III) with pyridine, triphenylphosphine, triphenylarsine, and 1,10-phenanthroline are reported. Rates are first order in ligand and half order in complex dimer in acetone. This suggests addition of the fifth ligand to an uncoordinated axial position of the square planar species as rate controlling. A (presumably) five coordinate intermediate can be detected kinetically on the way to six coordination in the reaction with 1,10-phenanthrioline and its rearrangement to an octahedral six coordinate chelate is slow. All these results may be interpreted in terms of the significant delocalized π bonding in the square planar dithiolene complexes.
Group vibrations
Authors: Freeman J. M. , Henshall T.
Published: May 2006

The procedure introduced by King and Crawford (1) for the factorization of group frequencies from the vibrational secular determinant is extended to cover more than two group frequencies in any symmetry species. The case in which the frequencies are not sequential is included.
Structure of an artifact formed during isolation of Penicilliumgladioli metabolites
Authors: Starratt A. N.
Published: May 2006

A new compound obtained from extracts of Penicilliumgladioli has been shown to be 3-ethoxy-4-hydroxymethyl-7-methoxy-6-methyl phthalide, an artifact formed from dihydrogladiolic acid during isolation.
The microwave spectrum, dipole moment, and structure of cyclopropyl carbinol
Authors: Bhaumik A. , Brooks W. V. F. , Dass S. C. , Sastry K. V. L. N.
Published: May 2006

The microwave spectra of cyclopropyl carbinol [Formula: see text] and its deuterated (—OD) form were studied in the region of 8 to 35 gHz. Only one of the possible rotational isomers was identified. The measured rotational constants and dipole moments for C3H5CH2OH and C3H5CH2OD are, respectively, A (mHz): 12485.13, 12064.04; B (mHz): 3236.46, 3177.22; C (mHz): 2894.38, 2826.19; κ: −0.928665, −0.924001; μa (D): 1.81, 1.78; μb (D): 0.36, 0.32; μc (D): 0.31, 0.30; μtotal(D): 1.87, 1.84.Rotation is apparently hindered by hydrogen bonding between the hydroxyl hydrogen and the electrons in the strained bonds of the cyclopropyl ring.
The photochemistry of aqueous solutions of Tl(III) perchlorate
Authors: Burchill C. E. , Wolodarsky W. H.
Published: May 2006

In deaerated aqueous perchloric acid solution Tl(III) is reduced and 2-propanol oxidized to acetone in equivalent yields via a chain reaction initiated by light of 2537 Å. Initiation is attributed to a charge-transfer-to-metal excitation followed by dissociation[Formula: see text]The formation of Tl(II) in the primary process is demonstrated by flash photolysis. An upper limit of 0.36 ± 0.07 is estimated for the primary quantum yield.
Pyrolysis of dimethylzinc and dimethylzinc-d6 by the toluene carrier method
Authors: Dunlop A. N. , Price S. J. W.
Published: May 2006

The pyrolysis of dimethylzinc has been studied over the temperature range 823–1015 °K using toluene to alkyl ratios from 51:1 to 121:1 and total pressure of 17 to 169 mm. The decomposition occurs in two steps[Formula: see text]By extrapolation to infinite pressure[Formula: see text]and at 10 cm pressure[Formula: see text]Assuming E2 must be increased by 2–4 kcal mole−1 to obtain E2 at infinite pressure D1 + D2 = 88 ± 4 kcal mole−1; cf. 86 ± 3 kcal mole−1 from thermochemistry. When dimethylzinc-d6 is used only traces of CD4 are produced. This indicates that the non free radical decomposition of methylzinc, suggested by the results of a previous sealed ampoule study, is not a significant process under the present experimental conditions.
Branched-chain 2-deoxy sugars. V. Application of the Wittig reaction to methyl 3,4-O-isopropylidene-β-D-erythro-pentopyranosid-2-ulose and attempted synthesis of nucleosides of 2-deoxy-2-C-methylpentoses
Authors: Rosenthal Alex , Sprinzl Matej
Published: May 2006

Oxidation of methyl 3,4-O-isopropylidene-β-D-arabinopyranoside (1) with ruthenium tetroxide afforded methyl 3,4-O-isopropylidene-β-D-erythro-pentopyranosid-2-ulose (2) in 78% yield. Condensation of methylenetriphenylphosphorane with 2 in the presence of H-butyllithium yielded methyl 3,4-O-isopropylidene-2-deoxy-2-C-methylene-β-D-erytho-pentopyranoside (3) in 55% yield. Reduction of the latter with 10% palladium-on-charcoal gave a 7:1 mixture of two isomeric 2-deoxy-2-C-methylpentoside derivatives in 95% yield: the preponderant product had the D-ribo configuration. The fully blocked methyl glycosides were de-isopropylidenated with methanolic hydrogen chloride to yield 6 and 7 and these were converted into the p-toluoyl esters (8) and (9). Attempts to utilize the latter in the synthesis of nucleosides of 2-deoxy-2-C-methyl pentoses were unsuccessful.
Electron spin resonance study of the 1,3,5-trinitrobenzene–NaOH system
Authors: Norris A. R. , Breck A. , Depew W. , Wan J. K. S.
Published: May 2006

Electron spin resonance spectra were observed in an aqueous system containing 1,3,5-trinitrobenzene and concentrated sodium hydroxide at 0 to 40 °C. From the hyperfine structure of the spectra and temperature studies, it is concluded that the paramagnetic species is a radical generated by reduction of a 1,3,5-trinitrobenzene–OH− σ-complex. The spectral assignments were supported by using deuterated 1,3,5-trinitrobenzene.
The chemical shift. I. Approximate theory and application to first row binary fluorides
Authors: Herring F. G.
Published: May 2006

Starting from the approximations of the i.n.d.o.-l.c.a.o.-s.c.f. method and using approximate Hartree–Fock perturbation theory, a method has been developed whereby the nuclear shielding of a nucleus for a first row element may be estimated. The method avoids the use of the average energy approximation. The method is demonstrated by calculating the 19F chemical shifts in the first row binary fluorides relative to the fluorine molecule.
Nuclear magnetic resonance study of anions derived from some carbon acids
Authors: Fyfe C. A. , Albagli A. , Stewart Ross
Published: May 2006

High resolution n.m.r. spectroscopy has been used to investigate the interaction of several nitrophenylmethanes with base and to characterize the species thus produced. In hexamethylphosphoramide (HMP) containing sodium methoxide, the n.m.r. spectra reveal that the anions present are formed by simple proton loss and this enables the u.v. spectra of these carbanions to be assigned. In less basic systems u.v. absorption occurs at lower wavelengths and n.m.r. spectroscopy reveals the presence of radical-anions.Previously observed spectral shifts brought about by solvent changes are thought to be due in whole or in part to the formation of radical anions and/or radicals. These are formed by electron transfer from carbanion to a neutral molecule of the nitro compound; this process is particularly important under less basic conditions, which cause the nitro compound to be only partly dissociated.
The Free Radical Photooximation of Alkanes by Nitrosyl Chloride
Authors: Mosher Melvyn W. , Bunce N. J.
Published: May 2006

The mechanism of the photooximation of alkanes with nitrosyl chloride has been reinvestigated. The lack of initiation of the reaction with free radical initiators suggests that a free radical chain pathway is not involved. Nevertheless, the relative reactivities of hydrocarbons of different structure and the deuterium isotope effect are very similar to those obtained in chlorinations with elemental chlorine, and in particular, primary and tertiary hydrogens are not inert to photooximation as has been previously supposed. A probable reaction mechanism involves hydrogen abstraction from the substrate by atomic chlorine in a free radical non-chain process. This hydrogen abstraction step is shown not to be significantly reversible.
Effects of Centrifugal Distortion and Nuclear Quadrupole Coupling in the Microwave Spectrum of Vinyl Chloride
Authors: Gerry M. C. L.
Published: May 2006

Both a- and b-type rotational transitions have been measured up to J = 30 for the two most abundant isotopic species of vinyl chloride, in the frequency region 8–18 GHz. These have enabled refinement of the rotational and chlorine nuclear quadrupole coupling constants, and evaluation of all first order centrifugal distortion constants. From the quadrupole coupling constants it is concluded that the field gradient around the C—Cl bond is somewhat more symmetric than previously reported. A comparison is made between the centrifugal distortion constants obtained from the microwave spectrum and those calculated using infrared data.
Theory of Ionic Conduction in Solids Based on the Homogeneous Generation of Defect Pairs and Its Application to Anodic Oxidation
Authors: Dignam M. J. , Taylor D. F.
Published: May 2006

The theory for ionic conduction in solids based upon the homogeneous, field-assisted generation of defect pairs is developed in a general, three dimensional form, and its range of applicability is examined. At high field strengths the equations reduce to those of the so-called high field Frenkel defect theory, proposed originally by Bean, Fisher, and Vermilyea. At low field strengths, the steady-state expression reduces to the well-known conduction equation derived originally by Mott for ionic conduction in the alkali halides. At intermediate field strengths, more complicated relationships obtain. The homogeneous generation of defect pairs, whether field or current assisted, is shown to be inapplicable as a mechanism for the high field anodic oxidation of the valve metals, since either type of theory predicts unacceptable behavior for the mean free path of the mobile defects. Any such conduction mechanism can be acceptable only for the case of thick films (» 104 Å).
Cinétique de l'oxydation du sous-oxyde de carbone en phase gazeuse
Authors: Lebel Jean , Ouellet Cyrias
Published: May 2006

The slow and the explosive combustion of carbon suboxide has been studied by the static method at pressures below 500 mm Hg and temperatures ranging from 560 to 680 °C. Reaction occurs in two distinct phases, [a] and [b], where [b] is inhibited by C3O2. The slow oxidation [a] is followed by[Formula: see text]oxidation [b] which is explosive at the lower pressures but slow above the upper pressure limit for CO–O2. Above another, higher pressure limit, the C3O2–O2 mixture explodes without delay. Water accelerates reaction a and lowers the pressure limits. Reaction a shows an over-all activation energy of 34 kcal/mol. We suggest that chain propagation takes place according to[Formula: see text]and that an energy chain leads to the branching reaction[Formula: see text]responsible for explosion.
A New Approach to 3′-Amino-3′-deoxynucleosides. Synthesis of 9-(3-Amino-3-deoxy-α-L-ribofuranosyl)adenine
Authors: Baer Hans H. , Bayer Monika
Published: May 2006

Methyl 2,3,4-tri-O-acetyl-6-deoxy-6-nitro-α-D-glucopyranoside (1) was acetolyzed to give 1,2,3,4-tetra-O-acetyl-6-deoxy-6-nitro-α-D-glucopyranose (2). Compound 2 (or alternatively, 6-deoxy-1,2-O-isopropylidene-6-nitro-α-D-glucofuranose 4) was converted into 2,3,4-tri-O-acetyl-6-deoxy-6-nitro-α- D-glucopyranosyl bromide (3) which was condensed with chloromercuri 6-benzamidopurine. De-O-acetylation of the condensation product 5 afforded 6-benzamido-9-(6-deoxy-6-nitro-β-D-glucopyranosyl)purine (6) which could be hydrogenated to the corresponding 6′-amino nucleoside 7. Periodate oxidation of 6 followed by internal Henry cyclization and borohydride reduction gave 6-benzamido-9-(3-deoxy-3-nitro-α-L-ribofuranosyl)purine (10) which upon catalytic hydrogenation and subsequent de-N-benzoylation produced the title compound, 12. The sensitivity of certain nitro intermediates towards alkali is commented upon.
Preparation and Properties of some Non-Metallic Derivatives of Pentafluorothiophenol
Authors: Peach M. E. , Spinney H. G.
Published: May 2006

Various non-metallic derivatives of pentafluorothiophenol, containing sulfur bonded to boron, carbon, silicon, germanium, phosphorus, arsenic, antimony, sulfur, and chlorine, have been prepared, mainly from the reaction of Pb(SC6F5)2 with a non-metallic halide, and characterized. The 19F n.m.r. spectra have been examined. The coordinating power of sulfur attached to a C6F5 group is minimal.
Synthesis and Thermolysis of 2H-1,2,3-Benzothiadiazine 1,1-Dioxide and 2,1-Benzoxathiin-3-one 1,1-Dioxide
Authors: King J. F. , Huston B. L. , Hawson Anne , Komery J. , Deaken Donna M. , Harding D. R. K.
Published: May 2006

2H-1,2,3-Benzothiadiazine 1,1-dioxide (6) and 2,l-benzoxathiin-3-one 1,1-dioxide (5), representatives of little-known heterocyclic systems, have been synthesized from sodium o-formylbenzenesulfonate (7). Thermolysis of 5 and 6 was investigated in the hope of finding evidence for the formation of a sulfene. No characterized product was obtained from 5, but 6 gave the sultine 3H-2,1-benzoxathiole 1-oxide (21), the compound expected from the sulfene 20.
Electronic Levels of Methyl Amines by Photoelectron Spectroscopy and an i.n.d.o. Calculation
Authors: Cornford A. B. , Frost D. C. , Herring F. G. , McDowell C. A.
Published: May 2006

The ionization potentials of the methyl amines down to 20 eV binding energy, have been determined by photoelectron spectroscopy, and are compared with those predicted by i.n.d.o.-l.c.a.o.-s.c.f. theory. The first ionization potential for each compound refers to the removal of an electron from the lone pair, and is shown to be the one most affected by the inclusion of one center repulsion integrals in the i.n.d.o. calculations.
Comment: On the Decomposition of Aqueous Sodium Dithionite
Authors: Wayman M. , Lem W. J.
Published: May 2006

In response to a comment by L. Burlamacchi, G. Guarini, and E. Tiezzi, kinetic equations for the decomposition of aqueous sodium dithionite are compared, and the mode of action of catalysts and anti-catalysts for the decomposition is discussed.
Reaction of Cyclopropenones with Heteroaromatic Nitrogen Compounds
Authors: Lown J. W. , Matsumoto K.
Published: May 2006

Diphenylcyclopropenone reacts with a variety of heteroaromatic nitrogen compounds to give in good yield either (a) 1,2-diphenyl-3-indolizinyl cis-1,2-diphenyl acrylates and aza analogs, (b) 5,6-diphenyl-7-hydroxypyrrolo[1,2-b]pyridazines and similar structures, or (c) adducts in which cycloaddition takes place to an N=N bond. Proof of structure of the new heterocycles is based on deuterium labelling experiments, hydrogenolysis to known compounds, and the preparation of chloro and iminoether derivatives. Cycloheptenocyclopropenones in the examples studied form heterocycles of type b.
Anionic Dimerization in Reductive Cleavage of an Allyl Ether with Sodium-Potassium Alloy
Authors: Hunter D. H. , Moore D. W.
Published: May 2006

The reaction of 9-methoxy-9-vinylfluorene (2a) with sodium–potassium alloy does not yield the expected 9-vinylfluorenylanion (1). The anions derived from the reaction were characterized by carbonation and subsequent methylation. Four esters (5, 6, 7, and 8) accounting for about two-thirds of the starting material were isolated and characterized. Structures were assigned on the basis of mass spectra and n.m.r. spectra in particular using decoupling experiments. A brief mechanistic scheme is presented.
L'isomérisation des acétates énoliques en série décalinique
Authors: Favre H. , Huet F. , Varfalvy L.
Published: May 2006

The reagent (acetic anhydride and perchloric acid in ethylacetate) proposed by Edwards and Rao for the enolacetylation of ketones is particularly well suited to the preparation of the enolacetates of cis and trans 2-decalones, and to the study of their equilibrium.
Benzodiazocines. II. The Synthesis of Some Hexahydro-1,4-benzodiazocines
Authors: Muchowski J. M.
Published: May 2006

The synthesis of some hexahydro-1,4-benzodiazocine derivatives by the dicyclohexylcarbodiimide (DCC) induced cyclization of the appropriate N-2-(2-aminophenyl)ethyl glycines is described. An analogous synthetic approach was used to prepare a hexahydro-1 H-1,5-benzodiazonine derivative.
Metal – Aminopolycarboxylic Acid Complexes. III. Studies of Lead(II) – Tetraethylenepentaamineheptaacetic Acid in Aqueous Solution by Proton Nuclear Magnetic Resonance Spectroscopy
Authors: Letkeman Peter , Sawyer Donald T.
Published: May 2006

Proton nuclear magnetic resonance (n.m.r.) spectroscopy and the pH dependence of the chemical shifts of the nonlabile protons have been used to determine the preferred protonation sites in tetraethylenepentaamineheptaacetic acid (TPHA). The nitrogen atoms are protonated more readily than the carboxylate groups with the sequence of protonation dependent on electrostatic interactions. The 1:1 Pb(II)–TPHA complex which is not protonated for solution conditions from pH 10 to 14, has five metal–nitrogen bonds. The coordinate bonds are labile so that rapid interconversion between nonequivalent configurations produces an average configuration in which the protons of the acetate groups exhibit single n.m.r. peaks. Protonation of the complex probably occurs in three stages. From pH 10 to pH 8 the preferred protonation sites are the terminal nitrogen atoms with the attendant elimination of the metal–nitrogen bonds. Increasing the acidity to pH 4 causes all but the central nitrogen site to be protonated. Below pH 4 the central nitrogen atom becomes protonated and causes further unwrapping of the complex.
Preparation of 5-Aminomethyl-2-thienylacetic Acid from 1-Methylthio-2-(2′-thienyl)ethyne
Authors: Raap R.
Published: May 2006

A five-step synthesis of 5-aminomethyl-2-thienylacetic acid is described starting from a 2-thienylethynyl thioether.
Synthesis of β-Poly-α-ethyl-L-aspartate
Authors: Moschopedis S. E. , Mumford C.
Published: May 2006

A simple procedure is described for the preparation of N-carboxy-L-aspartic anhydride α-esters, and the confirmation of the six-membered ring by i.r. and n.m.r. spectroscopic studies. The polymerization of N-carboxy-α-ethyl-L-aspartate to the corresponding β-poly-α-ethyl-L-aspartate is also described.
Nuclear Recoil Reactions in Organo-Manganese Compounds. V. —Mn(CO)5 Target Compounds
Authors: Jakubinek H. , Srinivasan S. C. , Wiles D. R.
Published: May 2006

HMn(CO)5, DMn(CO)5, CH3Mn(CO)5, and C6H5Mn(CO)5 have been irradiated with neutrons and the product spectrum of 56Mn-containing molecules determined. The results show that H56Mn(CO)5 is formed in all cases: 21.0%, 23.6% from HMn(CO)5 and DMn(CO)5 targets, respectively, and 6.9% and 2.1% from CH3Mn(CO)5 and C6H5Mn(CO)5, respectively. Thus the yields are not in accord with the number of H atoms per target molecule. Preliminary experiments show that •*Mn(CO)5 exchanges rapidly with HMn(CO)5 and DMn(CO)5 and very slowly with CH3Mn(CO)5 and C6H5Mn(CO)5. It is deduced that the very high yield of H56Mn(CO)5 in HMn(CO)5 and DMn(CO)5 targets could arise from the rapid exchange, while the lower yields of H56Mn(CO)5 in other targets must likely come from radical reactions following thermal dissociation of the target molecule.
Action du chloroformiate d'éthyle sur les lactames. Préparation sélective d'éthers lactimiques et de N-éthoxycarbonyl-lactames
Authors: Gauthier R. , Blondeau P. , Berse C. , Gravel D.
Published: May 2006

The reactivity of some carbocyclic lactams and some γ-thiolactams with ethyl chloroformate has been studied. At 25°, when reaction takes place, the corresponding lactim ether hydrochloride is formed in accord with the literature. At 110° however, the reaction yields the corresponding N-ethoxycarbonyl lactam in good yield. Investigation showed the free lactim ether to be a probable intermediate in this reaction.
Stereoselective Total Synthesis of (−)-Copacamphene and (−)-Cyclocopacamphene
Authors: Piers Edward , Britton Ronald W. , Keziere Robert J. , Smillie R. Dean
Published: May 2006

An efficient and highly stereoselective total synthesis of the novel sesquiterpenes (−)-copacamphene (1) and (−)-cyclocopacamphene (3) is described. This work fully corroborates the structure and absolute stereochemistry assigned to the two sesquiterpenes.
Synthetic Cardenolides and Related Products. II. Lactams
Authors: Ferland J. M. , Lefebvre Y. , Dinoi R. , Deghenghi R.
Published: May 2006

On treatment of cardenolides with ammonia or methylamine two isomers are obtained, 21-amino-14β,21-oxidonorcholan-23-oic acid lactam and 21-amino-14β-hydroxy-16β,21-oxidonorcholan-23-oic acid lactam. The assignment of stereochemistry to each isomer is based on the n.m.r. spectra and the correlation with the structure of isodigitoxigenin or isogitoxigenin.
The Effect of Counter Ion and Crosslinking on the Bulk Volume Magnetic Susceptibility of Dowex 50W
Authors: Weiner Paul H. , Howery Darryl G.
Published: May 2006

The bulk volume magnetic Susceptibility χv,p of packed beds of ten ionic forms of Dowex 50W having a crosslinking of 4, 8, and 12% divinylbenzene are measured using a spinning coaxial cell technique. Proton chemical shifts are referenced relative to external hexamethyldisiloxane (HMD). The measured values of χv,p range from −0.730 to −0.795 c.g.s. units. The absolute value of χv,p generally increases with an increase in atomic mass of the counter ion. For a given counter ion |χv,p| increases as the crosslinking increases. Chemical shifts for water external to and internal to the ion-exchange bead phase are corrected for bulk Susceptibility differences between the reference and the packed bed. The widths at half height of the external water peak increase with an increase in |χv,p|.
Mass Spectra of Spirobenzylisoquinoline Alkaloids
Authors: Yu C. K. , MacLean D. B.
Published: May 2006

The mass spectra of a number of spirobenzylisoquinoline alkaloids, several of their derivatives, and some model compounds are recorded and discussed. Fragmentation mechanisms are proposed for the formation of the major ions in the spectra of compounds containing one and two oxygen functions in the five-membered ring. The spectra of compounds containing a carbonyl group differ markedly from those having a hydroxyl group in the five-membered ring. Several model compounds were synthesized and characterized and their spectra compared with those of the alkaloids.
Thermodynamics of Ionization of Fluoroalcohols in Aqueous Solution: Hexafluoropropan-2-ol and Hexafluoropropan-2,2-diol
Authors: Woolley Earl M. , Hepler Loren G. , S. Roche Rodney
Published: May 2006

Calorimetric measurements have led to ΔH0 = 6.37 kcal mol−1 for ionization of aqueous hexafluoro-propan-2-ol (HFIP) and to ΔH0 = 6.00 kcal mol−1 for ionization of aqueous hexafluoropropan-2,2-diol (HFPD). We have combined these values with our ΔG0 values from pK = 9.42 for HFIP and pK = 6.65 for HFPD to obtain ΔS0 = −21.7 cal deg−1 mol−1 for ionization of aqueous HFIP and ΔS0 = −10.3 cal deg−1 mol−1 for ionization of aqueous HFPD. These results (all for 298 °K) show that most of the difference in pK values is due to the large difference in entropy of ionization. The ΔS0 values can be explained largely in terms of solute-solvent interactions.
Axial:Equatorial Rate Ratios and the Mechanism of Formation of Sulfenes by Dehydrohalogenation of Alkanesulfonyl Chlorides
Authors: King J. F. , Lee T. W. S.
Published: May 2006

The method of axial:equatorial rate ratios has been applied to the study of the mechanism of formation of sulfenes via the reaction of alkanesulfonyl chlorides with base. The axial trans-2-decalinsulfonyl chloride (6) and the equatorial trans-2-decalinsulfonyl chloride (8) were synthesized. The axial sulfonyl chloride 6 was found to react 71 times faster than the equatorial epimer 8 with triethylamine in the presence of aniline at −25°, a reaction which evidently proceeds via the sulfene 7. With water at 50° without added base (a reaction believed to take place by direct attack on the sulfur atom) 8 reacts about 14 times faster than 6. It is concluded that the formation of the sulfene 7 from 6 by the action of triethylamine cannot take place by a mechanism involving a slow SN2 reaction followed by a fast bimolecular elimination, and that the most likely route for 6, and other alkanesulfonyl chlorides as well, is the E2 reaction.
Metal Halide Ammines. 1. Thermal Analyses, Calorimetry, and Infrared Spectra of Cadmium Halide (Cl, Br, I) Derivatives
Authors: Patil K. C. , Secco E. A.
Published: May 2006

The thermal analyses of cadmium halide hexammines reveal that decomposition occurs by loss of ammonia via the diammine and the monoammine. Calorimetric measurements along with related enthalpic values for the intermediate stable stages of the decomposition reaction are given.The infrared spectral data of the diammines and monoammines are presented with their assignments.
Electronic Spectra of Nickel Chloride in Molten Amides
Authors: Stone M. E. , Johnson K. E.
Published: May 2006

Solutions of NiCl2 in molten acetamide and caprolactam have been investigated. The nature of the Ni(II) species present was found to be independent of concentration, over the concentration ranges 0.02 to 0.25 and 0.01 to 0.3 M, respectively; however, it was not independent of temperature. In both solvents, Ni(II) occurred mainly in octahedral environments but an increase in temperature apparently resulted in the formation of tetrahedral species.
Master Equation for the Dissociation of a Dilute Diatomic Gas. V. Effect of Energy-level Spacing
Authors: Mcelwain D. L. S. , Pritchard H. O.
Published: May 2006

Our previous vibration–dissociation coupling calculations for H2 have been repeated for D2. Closer spacing of the vibrational energy levels in D2 leads to increased translation–vibration transition probabilities, and the effect of this is to increase the rate of recombination by the vibrational mechanism at all temperatures. These numerical experiments also clarify two other issues: (i) that the position of the bottleneck does not necessarily occur at that level above which direct collisional dissociation can take place rapidly, and (ii) that there is no simple correspondence between the position of the bottleneck and the Arrhenius temperature coefficient for dissociation.
The Pyrolysis of Cumene, p-Cymene, and α-Methylstyrene at 800 °C
Authors: Severson Ray F. , Schuller Walter H. , Lawrence Ray V.
Published: May 2006

Cumene, p-cymene, and α-methylstyrene were pyrolyzed at 800 °C on Vycor glass. The products were separated by preparative g.l.p.c. and those identified were benzene, toluene, p-xylene, styrene, α-methyl-styrene, p-methylstyrene, indene, p,α-dimethylstyrene, naphthalene, 1- and 2-methylnaphthalene, di-phenyl, 2-vinylnaphthalene, acenaphthalene, fluorene, and phenanthrene. Possible mechanisms for the formation of these compounds are discussed.
Electrophilic Substitution in Methyl-Substituted Naphthalenes. II. The Hyperconjugative Model of the Methyl Group in PPP- and ω-Technique Calculations
Authors: Huy Le-Khac , Forst W.
Published: May 2006

A study of the dependence of common reactivity indices in 1,4-dimethylnaphthalene on the values of the parameters for the heteroatom model of the methyl group reveals that this model is not suitable within the Pople–Pariser–Parr formalism. However, if this model is used in conjunction with the ω-technique, two of the indices, superdelocalizability and localization energy, may give the correct order of reactive positions of 1,4-dimethylnaphthalene provided that an appropriate choice of parameter values is made.
Ions and Aggregates of Tetra-n-Butylammonium Picrate in Nonaqueous Solvents: A Thermodynamic Study
Authors: Goldman Saul , Cave G. C. B.
Published: May 2006

Values of ΔG0, ΔH0, and ΔS0 at 25 °C were obtained by distribution studies and by calorimetry, for the dimerization and trimerization of tetra-n-butylammonium picrate (1) in anhydrous benzene, chlorobenzene, and o-dichlorobenzene. The standard enthalpy of sublimation of 1 was calculated. The values of ΔG0 for the ionization, dimerization, and trimerization of 1 were linear functions of the reciprocal of the dielectric constant of the solvent. The intercepts and slopes of these graphs are interpreted; partial desolvation of the ions, and of the monomers on association is invoked. A simple potential function is used with the data, in order to deduce suitable models of the dimer and the trimer of 1.
Comments on the Infrared Spectra of SO2 Clathrate-hydrate Formed by Vapor Condensation
Authors: Hardin A. H. , Harvey K. B.
Published: May 2006

Gaseous mixtures having clathrate-hydrate stoichiometries were condensed at 83 °K into an amorphous phase. Infrared spectra were recorded at a series of temperatures up to 180 °K in order to determine the transformation temperature and the nature of the annealed phase. Bands associated with the H2O molecules began to shift position at 125 °K while those attributed to guest molecules decreased to null intensity. There was no evidence of a unique clathrate-hydrate H2O spectrum nor of free or hindered rotation of the guest molecules.
Vapor Phase Catalytic Transformations of Terpene Hydrocarbons in the C10H16 Series. II. Aromatization of α-Pinene over Chromia–Alumina
Authors: Stanislaus A. , Yeddanapalli L. M.
Published: May 2006

The aromatization of α-pinene in the vapor phase over chromia gel and chromia–alumina catalysts prepared from aluminas of different acidity has been studied. The acidity of alumina support has a remarkable influence on the composition of the aromatics resulting from the dehydrogenation of α-pinene. Over weakly acidic chromia–alumina doped with 1% sodium catalyst, α-pinene is aromatized to p-cymene, 1,2,4- and 1,2,3-trimethylbenzenes with traces of toluene and xylenes, whereas over the strongly acidic chromia – pure alumina and chromia–alumina containing 5% HF catalysts it gives considerable amount of m-cymene, toluene, and tetramethylbenzenes. A satisfactory mechanism to explain the formation of these compounds is offered.
The Adsorption of Alkylchlorosilanes on Quartz Crystal Surfaces
Authors: Khan G. M.
Published: May 2006

The piezogravimetric method has been used to study the adsorption of dimethyl and trimethylchlorosilanes on quartz crystal surfaces by varying the modes of treatment. The nature of the resulting low-energy surfaces has been discussed in the light of the extent of adsorption of n-hexane and water, calculated at different relative pressures, from their isotherms. The results obtained permit the conclusion that after the adsorption of silanes at 240 °C, the modified surface may be described as close-packed methyl surface, impenetrable to n-alkane and water vapour.
Spin–Orbit Relaxation of Hg(63P1) by Various Gases
Authors: Vikis A. C. , Torrie G. , Roy D. J. Le
Published: May 2006

The spin–orbit relaxation of Hg(63P1) to yield Hg(63P0) was investigated in the presence of various gases. The quantum yields of Hg(63P0) formation (defined as relaxation to Hg(63P0)/total relaxation) in the presence of CO, CO2, NH3, ND3, H2O, D2O, C2H6, c-C3H6, C(CH3)4, C3H8, 2,2-C3H6D2, C3D8, n-C4H10 and i-C4H10 were: 0.88 ± 0.07, <0.01, 1.05 ± 0.05, 1.00 ± 0.08, 0.76 ± 0.18, 1.06 ± 0.26, 0.64 ± 0.16, 0.56 ± 0.10, 0.58 ± 0.02, 0.14 ± 0.01, 0.51 ± 0.07, 0.47 ± 0.10, 0.11 ± 0.01, and 0.05 ± 0.01, respectively. The extent of the spin–orbit relaxation process appears to be related in an inverse manner to the availability and accessibility of channels leading to the formation of Hg(61S0), rather than to the fulfillment of electronic–vibrational resonance conditions. This in turn suggests the existence of Hg(63P1)—quencher intermediates having lifetimes long enough to permit several vibrations.
2,4-Diazapentadienes. II. A Carbanion Cyclization
Authors: Hunter D. H. , Sim S. K.
Published: May 2006

The mechanism of the cyclization and 1,3-proton shift of 1,3,5-triaryl-2,4-diaza-1,3-pentadienes (1) catalyzed by phenyllithium and by potassium methoxide–methanol has been studied. On the basis of substituent effects, hydrogen–deuterium exchange, isotope effects, and solvent effects, it was deduced that both the cyclization and prototropy involve a common W-shaped carbanion which rapidly cyclizes. A kinetic deuterium isotope effect of 2 was calculated for protonation of this intermediate carbanion in methanol.
Photoelectron Spectra of Phosgene and Thiophosgene
Authors: Chadwick David
Published: May 2006

The high resolution photoelectron spectra of phosgene and thiophosgene have been obtained and, in each case, all ionization potentials up to 21.2 eV determined. The spectra are interpreted in terms of the molecular orbital structures and it is concluded that there is a strong interaction between the chlorine pπ "lone pair" electrons and those in the C=O or C=S π bond. The measured ionization potentials are compared with those calculated by the CNDO/2 method and with those obtained for similar molecules.
Relationship of 13C to Vicinal 1H Coupling to the Torsion Angle in Uridine and Related Structures
Authors: Lemieux R. U. , Nagabhushan T. L. , Paul B.
Published: May 2006

Uracil was prepared enriched at C2 with carbon-13 and converted into uridine from which 2,5′-anhydro-1-β-D-ribo-furanosyl and 2,2′-anhydro-1-β-D-arabino-furanosyl uracil were prepared. The 13C2 to vicinal proton coupling constants for these compounds were measured and are compared in terms of the expected torsion angles defined by the two atoms. The evidence suggests the existence of a Karplus-type relationship as is found for vicinal proton coupling. The data establish the anti conformation for uridine in solution.
Field and Resonance Components of Substituent Effects in Relation to the Hammett Equation
Authors: Hansen L. D. , Hepler L. G.
Published: May 2006

Following Swain and Lupton's analysis of substituent effects, we have taken ΔG0 = aete + artr for a typical substituent effect reaction. In this equation ae and ar are substituent constants for electrostatic field and resonance effects while te and tr are corresponding transmission coefficients. Both substituent constants and tr are taken to be independent of solvent and temperature, while te is taken to depend on both solvent and temperature. General conclusions based on analysis of this model are the following. (i) A Hammett ρσ equation with constant σ values that are valid over a range of temperatures for a variety of reactions in several solvents can be obtained only when either the field or the resonance interaction is negligible compared with the other. (ii) A Hammett ρσ equation can be expected to hold for "similar" reaction series in a given solvent at one temperature even when both the field and resonance interactions are important, (iii) An isoequilibrium or isokinetic relationship can be expected only when the field interaction is dominant.The general equations leading to these and other conclusions are presented so that one can later insert appropriate mathematical descriptions of detailed models and thereby obtain information about specific reactions.
Effect of Electric Field Strength on the Free Ion Yields in the X-Radiolysis of Liquids: Influence of Molecular Structure and Temperature
Authors: Dodelet J.-P. , Fuochi P. G. , Freeman G. R.
Published: May 2006

The relative increase in the free ion yield with increasing field strength E, expressed as [Formula: see text] is smaller when the following quantities are larger: (1) dielectric constant, (2) temperature, and (3) separation distance between the geminate ion–electron pairs. The field dependence [Formula: see text] equals 9.7/εT2 cm/V at low E, but at higher fields it is affected by the above three factors and by E itself. Results obtained from the liquids propane (123–233 °K), 2-methylpropane (isobutane, 148–294 °K), 2,2-dimethylpropane (neopentane, 295 °K), argon (87 °K), oxygen (87 °K) and argon–oxygen solutions (87 °K) are presented and analyzed according to a theoretical model. Several types of ion–electron separation (y) distribution functions are tested. Within the framework of the model a power function F(> y) = yminy−x with x < 4 provides a good interpretation of the results when [Formula: see text] a Gaussian distribution function provides the best interpretation of the field effects when [Formula: see text] Either the y distribution has a Gaussian core with a more gently sloping tail, or distributions are more Gaussian-like in liquids in which the electron ranges are greater. The electron range in pure argon (b = 1300 Å) is much smaller than had been expected and is only 2.6 times greater than that in liquid methane (b = 500 Å at 120 °K). Phonon emission by 10–0.01 eV electrons in liquid argon may be relatively efficient and might involve transient states of the type [Formula: see text]
Approaches to the Synthesis of Triterpenoids. II. Some Tetracyclic Precursors Suitable for Conversion into Pentacyclic Triterpenoids
Authors: ApSimon J. W. , Baker P. , Buccini J. , Hooper J. W. , Macaulay S.
Published: May 2006

The stereoselective total synthesis of several partially reduced chrysene derivatives, suitable as precursors for a variety of triterpenoids, is described. The key reaction in the most efficient route involves the highly stereoselective reductive alkylation of a cyclic α,β-unsaturated ketone with allyl bromide in lithium–ammonia, using water as a proton donor.
13C-Nuclear Magnetic Resonance Spectrum of Tropolone
Authors: Weiler Larry
Published: May 2006

The 13C-n.m.r. spectrum of tropolone has been obtained and it clearly shows that there is a rapid tautomeric equilibrium at room temperature. The peaks have been tentatively assigned using calculated π charge densities and nuclear Overhauser enhancements.
A New Synthesis of "Schöpf's Base VI" and Related 10H-Isoindolo[2,3-c] benzazepines
Authors: Teitel S. , Klötzer W. , Borgese J. , Brossi A.
Published: May 2006

The 10H-isoindolo[2,3-c][3]benzazepines, "Schöpfs base VI" (4a) and its 4-methoxy derivative 4b, have been prepared by a new and facile synthesis which utilized intermediates derived from phthalideisoquinoline alkaloids.
The Thermal Behavior of Some Resin Acids at 400–500 °C
Authors: Severson Ray F. , Schuller Walter H.
Published: May 2006

The hot tube pyrolysis of dehydroabietic acid (1) at 400–500 °C was found to produce as major products the three possible A-ring olefins (19-norabieta-4,8,11,13-tetraene (2); 19-norabieta-4(18),8,11,13-tetraene (3); and 19-norabieta-3,8,11,13-tetraene (4)) resulting from the elimination of the carboxylate moiety. The i.r., n.m.r., u.v., and mass spectrum of each olefln was obtained and discussed. The pyrolysis of abietic acid (7) and levopimaric acid (8) under identical conditions was found to yield A-ring olefins; to isomerize to yield varying mixtures of palustric, 7, and neoabietic acids; to dehydrogenate to yield 1; and to eliminate propylene to form deisopropyldehydroabietic acid (15). A mechanism to explain the formation of 15 from the dienoic resin acids is given.
La photo-oxydation du Hg(I) par le Ce (IV) en solution aqueuse d'acide perchlorique
Authors: Nuyt A. , Zador M.
Published: May 2006

The photo-oxidation of Hg(I) by Ce(IV) has been studied at 366 mμ in aqueous perchloric acid solutions. The quantum yield depends on the concentrations of both Hg(I) and Ce(III). This dependence is different at high and low absorptions. There is a marked increase of the quantum yield with the acid concentration. It is proposed therefore that Ce4+ is the species involved in the primary photochemical process.
Adducts of Piperidine, Piperazine, Methylpiperazine, and Morpholine with Bis(β-Ketoenolates) of Nickel(II)
Authors: Marcotrigiano G. , Battistuzzi R. , Pellacani G. C.
Published: May 2006

The bis(β-ketoenolates)nickel(II) adducts of piperidine, piperazine, methylpiperazine, and morpholine are isolated in the solid state and investigated by magnetic measurements and electronic and i.r. spectra. Magnetic measurements and electronic spectra give evidence of trans-octahedral configuration while i.r. spectra show that the amines are coordinated to the nickel atom towards the nitrogen atom. The new band found in the range 385–300 cm−1 for all complexes can be assigned to Ni—N vibration. In the Ni(DBM)2•4B (B = methylpiperazine and morpholine) the two additional bases are not coordinated to the metal atom.
The Reaction of some Isothiazolium Salts with Sulfur in Pyridine
Authors: Bachers G. E. , McKinnon D. M. , Buchshriber J. M.
Published: May 2006

A variety of N-methyl and N-phenylisothiazolium salts has been synthesized and treated with sulfur in boiling pyridine. The products have been examined by chromatography and their structures determined. While 5-unsubstituted isothiazolium salts appear to give the corresponding isothiazoline-5-thiones, 3-unsubstituted salts give either the corresponding isothiazoline-3-thiones if the nitrogen is alkyl substituted, or 1,2-dithiole-3-imines if the nitrogen is aryl substituted. N-Alkyl compounds also give dealkylated products, and dithiolethiones are also found. The initial stages in the reaction appear to involve deprotonation of the isothiazolium salt.
Temperature and Pressure Dependence of 209Bi Nuclear Quadrupole Resonance in BiCl3
Authors: Gillies G. C. , Brown R. J. C.
Published: May 2006

The temperature and pressure dependence of the 209Bi nuclear quadrupole coupling constant and asymmetry parameter in solid BiCl3 have been measured near room temperature. It is not possible to account for the results on the basis of the conventional theory in which the field gradient parameters depend only on the crystal volume.
Conformations of Bridged Diphenyls. II. Crystal Structure of 2-(2′,4′-Dinitrophenoxy)-1,3,5-tri-t-butylbenzene
Authors: Griffith E. A. H. , Chandler W. D. , Robertson B. E.
Published: May 2006

The structure of 2-(2′,4′-dinitrophenoxy)-1,3,5-tri-t-butylbenzene, C24H32N2O5, has been determined by X-ray diffraction. The crystals are triclinic, a = 12.160(30), b = 10.564(17), c = 10.684(16) Å, α = 119.23(10), β = 96.06(15), γ = 96.55(15)°, [Formula: see text] with Z = 2. The intensities of 5359 independent reflections were measured on a four circle diffractometer of which 2471 were used in the refinement to give a final least-squares weighted residue of 0.063. The presence of two electron withdrawing groups on one of the phenyl rings increases the conjugation between the ring and the ether oxygen atom to a greater degree than was found in the previous work. The tri-t-butyl-substituted ring is nearly orthogonal to the other ring. The bond angle at the ether oxygen atom is less than the value found earlier but ring distortions are similar.