bluuebunny/crossref_metadata_2025 huggingface dataset:
Synthesis of 5-substituted ether derivatives of 5-hydroxymethyldeoxyuridine and their α-anomers
Authors: Bubbar G. L. , Gupta V. S.
Published: May 2006

The synthesis and properties of ether derivatives 6a–d of 5-hydroxymethyldeoxyuridine and their corresponding α-anomers 7a–d are described. Acid-catalyzed etherification of 5-hydroxymethyluracil (1) gave the corresponding 5-alkoxymethyluracils 2a–e in excellent yields. Treatment of compounds 2a–e with trimethylchlorosilane gave bis(trimethylsilyl)pyrimidines 3a–e in high yields which, upon condensation with 3,5-di-(O-p-toluoyl)-2-deoxy-D-ribofuranosyl chloride, furnished an anomeric mixture of substituted nucleosides, β-anomers 4a–e and a-anomers 5(a–e). The nucleosides with β-configuration were the major products in each case and were recovered as crystalline solids in good yields. Deblocking of compounds 4a–d by alcoholysis resulted in the corresponding ether derivatives 6a–d. From mother liquors, two substituted α-anomers, 5a, b were isolated as crystalline solids in small yields. Compounds 7c, d were obtained from mother liquors after hydrolysis by using preparative t.l.c. The structures were confirmed on the basis of p.m.r. studies, u.v. and i.r. absorption spectra, and elemental analysis. The compounds 2a–e and 6a–d did not inhibit thymidylate synthetase at a concentration of 2.5 mM.
Déplacement chimique du proton en résonance magnétique nucléaire. I. Calcul du terme diamagnétique en vue de son utilisation à l'étude de la structure des molécules. Application aux éthers vinyliques
Authors: Tonnard François , Odiot Simone , Martin Maryvonne L.
Published: May 2006

A relation between the diamagnetic term for a proton bonded to a carbon atom and the linear combination of atomic orbital charges on C and H is established. Proton diamagnetic terms of some vinyl ethers are calculated, and the conformation of ethoxy group in these molecules studied.
Vapor pressures and vapor liquid equilibria in the systems: (1) acetone – chloroform, (2) acetone – carbon tetrachloride, (3) benzene – carbon tetrachloride
Authors: Campbell A. N. , Musbally G. M.
Published: May 2006

The saturation vapor pressures of ten mixtures of the binary systems (1) acetone – chloroform, (2) acetone – carbon tetrachloride, and (3) benzene – carbon tetrachloride have been determined, from 100 to 230° for system 1 and from 100° up to the highest temperature at which liquid and vapor coexist for systems 2 and 3. The system acetone – chloroform could not be studied at higher temperatures because of decomposition.The gas–liquid critical temperatures of the three binary systems have been determined by the disappearance of meniscus method. The orthobaric compositions of the vapour–liquid equilibria of the binary systems have been measured from 100 to 180° for system 1 and from 100° to the critical region for systems 2 and 3, using a glass bomb enclosed in a steel bomb.From the vapour–liquid composition curves and the vapor pressure curves at constant temperatures (100, 150, 160, 170, and 180°), the existence of an azeotrope in the system acetone–chloroform at these temperatures, and having a composition of 36.2 mole% acetone at 100°, was confirmed. The composition of the azeotrope shifts towards lower acetone content as the temperature is raised. Azeotropes were not found in the systems acetone – carbon tetrachloride and benzene – carbon tetrachloride, over the ranges of temperature and pressure of this research.The data of the binary systems were treated thermodynamically to yield the liquid phase activity coefficients and, as suggested by Chueh and Prausnitz, the Redlick–Kwong equation was used in a modified form to obtain the fugacity coefficients of components in the vapor phase. Several liquid phase parameters, such as the binary interaction constant, Henry's constant, and dilation constant have been calculated, using the van Laar equation as modified by Chueh and Prausnitz.
The kinetics of the thermal insertion reaction of tin(II) halides with cyclopentadienyliron dicarbonyl dimer
Authors: Barrett P. F. , Sun Kenneth K. W.
Published: May 2006

The kinetics of the thermal insertion reaction of SnBr2 and SnCl2 with the metal–metal bonded dimer [π-C5H3Fe(CO)2]2 have been studied by following the change in the visible spectrum. The kinetic data are consistent with a two-stage mechanism involving the formation of a carbonyl-bridged intermediate followed by nucleophilic attack by the halides on this intermediate. The formation of the intermediate requires an activation enthalpy of 38.0 ± 1.0 kcal/mole, and an activation entropy of 45.5 + 1.5 cal mole−1 deg−1. The activation energy required to break the Fe—Fe bond is estimated to be about 32 kcal/mole.
Effets de solvant sur les fréquences des vibrateurs CD et CH de quelques haloformes
Authors: Rossi Inga , Thanh Nguyen-Van- , Brodbeck Claude , Haeusler Claude
Published: May 2006

The frequencies of the fundamental C—D and C—H stretching band and the overtones have been measured for CDCl3 and CHBr3 in some nonpolar and some slightly polar solvents.We have pointed out that the mechanical anharmonicity of these vibrations is strong and solvent-dependent. Therefore, the approximation [Formula: see text] is not valid for the vibrators considered in this work.The solute–solvent interaction energy is the sum of induction, dispersion, and orientation energies (for polar solvents). Calculations based on the cell model for the liquid state showed that induction energy is of slight influence with respect to dispersion energy, which is greatly responsible for the observed frequency shift.
Electron spin resonance studies of radiation damage. Part IV. The effect of photobleaching on the trapped radicals in gamma irradiated 2-methyltetrahydrofuran glasses at 77 °K
Authors: Sargent F. P.
Published: May 2006

The concentration of trapped radicals was found to decrease during the course of photobleaching trapped electrons in gamma irradiated 2-methyltetrahydrofuran glasses at 77 °K.
Decomposition of BrO studied by kinetic spectroscopy
Authors: Brown J. , Burns George
Published: May 2006

Kinetics of BrO decomposition was studied between 293 and 673 °K using the technique of kinetic spectroscopy. At 293 °K the reaction rate is second order with respect to BrO and is independent of [Br2], [O2], and total pressure of diluent gas. The activation energy for decomposition obtained from rate measurements between 293 and 450 °K is 0.65 ± 0.05 kcal/mole. Above 450 °K this activation energy appears to increase to 4.5 kcal/mole. It is shown that, although kinetically the ClO and BrO decompositions are similar, the mechanism for BrO decomposition below 450 °K is much simpler than that of ClO. The reaction proceeds, most likely, via one step: 2 BrO → 2 Br + O2, with Br2O2 being an activated complex, which has either linear or staggered configuration. ClO and BrO decomposition is compared with [Formula: see text] reaction.
The chemical shift. II. A study of 14N chemical shifts in nitrogen–oxygen–halogen compounds
Authors: Aubke F. , Herring F. G. , Qureshi A. M.
Published: May 2006

The chemical shifts of the 14N nucleus in a number of nitrogen–halogen–oxygen compounds have been estimated within the framework of the i.n.d.o.-l.c.a.o.-s.c.f. method using approximate perturbed Hartree–Fock theory. Generally good agreement with experiment is achieved. The calculations indicate that the variation in 14N chemical shift is due to either changes in orbital angular momentum, or to the presence of low lying excited states, or to a combination of both effects.
Studies in ferrocene derivatives. IX. The dimerization of α-ferrocenyl carbonium ions
Authors: Horspool W. M. , Sutherland R. G. , Sutton J. R.
Published: May 2006

Ferrocenylethylenes dissolve in 90% HCOOH to give solutions of the α-ferrocenyl carbonium ions in equilibrium with the unprotonated species. These subsequently react by an ionic-addition mechanism to give dimeric carbonium ions which can cyclize by both homo-and heteroannular pathways.
Hydrogen–deuterium exchange of medium ring cycloalkenes during deuterogenation with tris(triphenylphosphine)chlororhodium(I)
Authors: Atkinson J. G. , Luke M. O.
Published: May 2006

Cyclooctene, and, to a lesser extent, cycloheptene and cyclododecene undergo H–D scrambling during deuterogenation with tris(triphenylphosphine)chlororhodium(I), whereas this catalyst affords clean addition of two deuterium atoms to cyclohexene and 1-octene. Cyclooctene containing up to 0.4 deuterium atoms per molecule has been isolated after 50% reduction and the isotope shown to be randomly distributed about the ring. This unexpected exchange reaction has been accounted for in terms of the medium size ring effect (I-strain) and provides impressive further evidence for the reversible formation of a normally unobserved rhodium–alkyl species as an intermediate in the hydrogenation reaction.
Basicities of organometallic and other bases using the visible absorption maximum of the reference acid and its conjugate base
Authors: McLean R. A. N. , Umpleby J. D.
Published: May 2006

The shift in the visible absorption maximum of hexanitrodiphenylamine has been used as a measure of the base strengths of some organometallic and organic bases. It is not possible to obtain a quantitative measure for stronger bases as the hexanitrodiphenylamine anion is produced. The order of base strengths for the organometallic bases studied is found to be Me3SiSMe < Me3CSMe < Me3SnSMe ≈ Me3SiNMe2.
Electron paramagnetic resonance spectra of some sulfur-containing radicals
Authors: Bolman P. S. H. , Safarik I. , Stiles D. A. , Tyerman W. J. R. , Strausz O. P.
Published: May 2006

The e.p.r. spectra from the low temperature matrix photolysis of several mercaptans, disulfides, and cyclic sulfides have been recorded and compared to those obtained in the photolysis of these materials adsorbed on a porous Vycor glass. The spectra of the adsorbed radicals are characterized by an enhanced thermal stability and a shift of the highest sulfur g-value to higher fields. The only free radical product in the photolysis of mercaptans and disulfides is the thiyl radical. The cyclic sulfides [Formula: see text] appear to yield•CH2—(CH2)n—S•type diradicals, while the cyclic disulfide [Formula: see text][Formula: see text] gives the [Formula: see text] diradical.
Base-catalyzed protium–deuterium exchange in bicyclo[2.2.1]heptanones
Authors: Werstiuk Nick H. , Taillefer Roland
Published: May 2006

The rates of NaOD-catalyzed protium–deuterium exo exchange in fenchan-2,5-dione (2) and 1-methyl-5-oxo-camphene (3) are 200 and 7, respectively, relative to epiisofenchone (1). The endo exchange rates in 2 and 3 are 1840 and 4, respectively, relative to 1. These data give information about the relative importances of conjugative, conformational, inductive, strain, and steric effects which may arise when a carbonyl group or a double bond is situated 1,3 to an enolizable center in the 2.2.1 system.
Pyrrole Chemistry. Part XI. Some Reactions of the Pyrrole Grignard Reagent with Alkyl Carbonates and Alkyl Thiocarbonates
Authors: Loader C. E. , Anderson Hugh J.
Published: May 2006

The pyrrole Grignard reagent reacts with ethyl thiocarbonates to give good yields of ethyl 2-pyrrole-thiocarboxylates.Diethyl carbonate, by contrast, in accordance with earlier reports gives almost exclusively ethyl 1-pyrrolecarboxylate.2-Pyrrolecarbonitrile was prepared in good yield from the pyrrole Grignard reagent and ethyl thiocyanate.
The Transmission of Substituent Effects in Transition Metal Complexes
Authors: Eaton D. R. , Chua K. L.
Published: May 2006

The effect of ligand substitution on bonding to other ligands has been investigated in a series of V(III) complexes. Nuclear magnetic resonance (n.m.r.) contact shifts have been utilized for this purpose. These shifts are interpreted as arising from metal to ligand charge transfer. The results obtained are contrary to those expected from simple considerations of the electron withdrawing or donating abilities of the substituents. Electron withdrawing substituents decrease the charge transfer to the substituted ligand and increase the charge transfer to the remaining ligands. Electron donating substituents have the opposite effect. A simple interpretation is proposed to account for these results. An electron withdrawing substituent on a ligand in the xy plane increases the occupancy of dxy which cannot interact with the π system of the ligand in the xy plane but which is available for π bonding with the remaining ligands. Effects of this type are to be anticipated whenever the filling of the t2g orbitals is not symmetrical.
Structure of Fumarophycine
Authors: Castillo M. , Saunders J. K. , MacLean D. B. , Mollov N. M. , Yakimov G. I.
Published: May 2006

Fumarophycine, an alkaloid derived from Fumaria officinalis of Bulgarian origin, is shown by spectroscopic methods to be a new member of the spiroisoquinoline group. It has been related by chemical methods to the alkaloid, fumaritine, of known constitution.
Magnetic Resonance Studies of Metal Olefin Complexes. II. Electron Spin Resonance Spectra of γ-Irradiated Silver Complexes with Cyclohexadienes and 1-Methyl Cyclopentene
Authors: Gee D. R. , Wan J. K. S.
Published: May 2006

Electron spin resonance studies of silver cycloalkenyl radicals by γ-irradiation of polycrystalline silver cycloalkene complexes have been extended to include the effect of alkyl substitution at the double bond, the effect of conjugation in cyclic diolefins and the effect of anions, on the formation of these silver cycloalkenyl radicals.
The Crystal Structure of a Thiathiophthen Nitrogen Isostere, 3,5-Epidithio-2,5-diphenyl-2,4-pentadienylidene-3-aminoquinoline
Authors: Leung F. , Nyburg S. C.
Published: May 2006

The crystal structure of a thiathiophthen nitrogen isostere (7) has been solved by X-ray analysis. The crystal belongs to the triclinic system with unit cell dimensions: a = 11.275(11), b = 9.558(10), c = 10.797(10) Å, α = 92.50(10), β = 116.98(10), γ = 92.61(10)°. There are two molecules per unit cell, space group [Formula: see text]. The data were collected by diffractometer with CuKα radiation. The structure was solved by symbolic addition procedures, and fully refined anisotropically using full-matrix least squares to an R factor of 6.3%.The S—S and S—N bond lengths were found to be 2.364 and 1.887 Å, respectively. This reveals the partial bonding character between S … S … N atoms.
Reactions of Some Allylic and Propargylic Halides with Nucleophiles Analogous to Those Present in Proteins and Nucleic Acids
Authors: Jones J. Bryan , Hysert David W.
Published: May 2006

The relative alkylating capabilities of crotyl chloride, allyl bromide, and 1-bromo-2-butyne with respect to compounds containing thiol, imidazole, primary amino, and methylthio functions representative of those present in cysteine, histidine, lysine and methionine residues have been studied using 2-bromoacetophenone as the reference alkylating agent.
Hydrocarbon Complexes of Iron Carbonyls Formed Photochemically in Argon Matrices at 17 K
Authors: Newlands M. J. , Ogilvie J. F.
Published: May 2006

Irradiation of pentacarbonyliron with ethene in an argon matrix gives (C2H4)Fe(CO)4, while ethyne reacts with the carbonyl under similar conditions to give a complex of 1-buten-3-yne.
Photochemistry of Steroid 4-en-3-one 11α-Nitrites. A Novel Synthesis of A-Nor-B-homo Steroids
Authors: Reimann Hans , Sarre Olga Z.
Published: May 2006

Photolysis of some 11 α-hydroxysteroid 4-en-3-one nitrites afforded 1-oximinosteroid 4-en-3-ones and 9a-methyl-B(9a)-homo-A-norsteroid 3(5),9a-dien-2-ones. Chemical and physical evidence for the latter, as well as a plausible mechanism for the transformation, is presented.
Bicyclo[2.2.1]heptyl phosphonates. III. Radical Addition of Dimethyl Phosphonate to Norbornadiene
Authors: Callot Henry J. , Benezra Claude
Published: May 2006

Radical addition of dimethyl phosphonate to norbornadiene was found to give four main compounds 2, 3, 4, and 5 whose structures have been demonstrated by chemical and spectroscopical methods. Particularly noteworthy is the formation of norbornene phosphonate derivatives in addition to the nortricyclene derivatives.
Mobility of Phosphorescent Solutes in Polymethylmethacrylate
Authors: Woods R. J. , Manville J. F.
Published: May 2006

Nuclear magnetic resonance measurements upon polymerizing methyl methacrylate solutions show that a significant proportion of the solute molecules (naphthalene, phenanthrene) remain untrapped when the material becomes solid (60–30% residual unsaturation), complete rigid trapping of the solute occurring only as the unsaturation present is reduced to near zero.Phosphorescence measurements show increasing phosphorescence from solid polymethylmethacrylate containing phenanthrene as the residual unsaturation in the polymer is reduced from about 4% to zero, which is attributed to the gradual immobilization of an increasing fraction of the solute molecules as the unsaturation is reduced. Methyl isobutyrate reduces the phosphorescence from solutions of phenanthrene in polymethylmethacrylate at room temperature, but polymer solutions containing methyl isobutyrate and those containing residual unsaturation phosphoresce strongly at 77 °K.
Alkaloids of Lycopodium alopecuroides. Part 4. The Structure of Lycopecurine
Authors: Ayer William A. , Masaki Norio
Published: May 2006

Lycopecurine, an alkaloid of Lycopodium alopecuroides has been shown by an X-ray crystallographic study of the hydrobromide to possess structure 2.
Structure of the Amino Sugar Component in Baker's Yeast Mannan
Authors: Gorin P. A. J.
Published: May 2006

Baker's yeast mannan was methylated and the fully methylated polysaccharide hydrolyzed. The product contained a trace of 2-deoxy-3,6-di-O-methyl-2-methylamino-glucose which was characterized chromatographically. It likely arose from one or more 4-O-substituted 2-acetamido-2-deoxy-D-glucopyranose units (or the 5-O-substituted furanosyl isomer). One possibility is that it arose from a 4-O-substituted 2-acetamido-(1-L-β-aspartamido)-1,2-dideoxy-β-D-glucopyranose unit which is probably the bridge in one of the carbohydrate-peptide links in the glycoprotein of the cell wall.
The Effects of Substituents on the Abstraction of Halogens by Fluoroalkyl Radicals
Authors: Moore Leonard O.
Published: May 2006

The relative reactivities of halogens to abstraction by fluoroalkyl radicals at 125° have been found to be 58.0 for—CF2—I, 4.9 for—CF2—Br, 1.8 for —CCl2—Cl, and 1.0 for —CClF—Cl. The nature of halogens on adjacent carbons does not appear to affect the reactivity significantly.
Dielectric Relaxation of the Butyl Alcohols in p-Xylene Solution
Authors: Crossley John
Published: May 2006

Dielectric constants and losses of the four butyl alcohols have been measured at concentrations of 0.02–0.12 mol fraction in p-xylene solution over the frequency range 1–35 GHz at 25 °C. The data for the most dilute solutions can be represented by a symmetrical distribution of relaxation times. For the mole concentrated solutions the Cole–Cole plots indicate a separation into two absorption regions and the data can be analyzed in terms of two relaxation times both of which lengthen with increased alcohol concentration. The contribution from the long relaxation time and the apparent dipole moment for each butanol, is independent of alcohol concentration and decreases in the order n-butanol > iso-butanol > sec-butanol > t-butanol. The results are discussed in terms of previous dielectric relaxation studies of pure liquid aliphatic alcohols and their solutions in non-polar solvents.
Peptide Conformations. I. Nuclear Magnetic Resonance Study of the Carbamate Reaction of Amino Acids and Peptides
Authors: Lemieux R. U. , Barton M. A.
Published: May 2006

Nuclear magnetic resonance spectroscopy has been applied to the study of carbamate formation in solutions of amino acids and peptides in a carbonate-bicarbonate system. The possible conformations of these carbamates are discussed in terms of the n.m.r. data obtained. The n.m.r. parameters are reported for the diastereomers L-alanyl-L or D-phenylalanine and L-phenylalanyl-L or D-alanine and for the dipeptide glycyl-L-phenylalanine and their carbamates. The results are interpreted in terms of preferred rotamers about the Cα—Cβ bond of the phenylalanine residue and a β-type conformation of the peptide chain, wherein the two α-protons lie in the plane of the amide bond. All observations are in agreement with a shorter end to end distance in L,D- compared with L,L-dipeptides.
Conformation in Solution of 1,1,2,3,4,4-Hexachlorobutane
Authors: Rowbotham J. B. , Hutton H. M. , Schaefer T.
Published: May 2006

Commercially available (Aldrich) 1,1,2,3,4,4-hexachlorobutane is as the meso isomer. On the basis of the values of the three distinct proton–proton coupling constants it is concluded that, with respect to the C—H bonds, the conformation is gauche about the C1—C2 bond and trans about the C2—C3 bond.
The Total Synthesis of a Thebaine Analogue and of the Corresponding "Bentley Adduct"
Authors: Wiesner K. , Mccluskey J. G. , Chang J. K. , Šmůla V.
Published: May 2006

We are reporting the synthesis of the thebaine analogue 6 in which the nitrogen atom has been translocated within the ethanamino bridge from position 17 to 16. This compound has been further transformed by successive Diels–Alder and Grignard reactions into the derivative 3.
Synthesis of D-Idurone
Authors: Sowa Walter
Published: May 2006

D-Idurone was prepared by periodate oxidation of D-glycero-D-ido-heptonolactone.
Radiation Effects with a Model Lipid Membrane
Authors: Petkau A.
Published: May 2006

A cell is described that permits a model phospholipid membrane and the two adjacent aqueous compartments to be irradiated with a collimated beam of X-rays. During a 2 h irradiation a marked increase in [H+] in the aqueous phases is observed. A protonmotive force, given by the H+ Nernst potential, is generated when one compartment only is irradiated or when both compartments separated by a membrane made structurally asymmetric by the adsorption of alamethicin, are irradiated equally.The results of irradiations in N2O, N2, and O2 indicate that the membrane scavenges the superoxide O2−. The effect is discussed in terms of a clearing field that is derived from the potential at the membrane interfaces.
Mass Spectra of the Hydroxyindole-3-carboxylic Acids and the Hydroxyskatoles
Authors: Marchelli Rosangela , Jamieson W. D. , Safe S. H. , Hutzinger O. , Heacock R. A.
Published: May 2006

The electron impact fragmentations of the 4-, 5-, 6-, and 7-hydroxyskatoles and the 4-, 5-, 6-, and 7-hydroxyindole-3-carboxylic acids have been studied. The spectra of the four isomeric hydroxyskatoles are virtually indistinguishable, due to substituent randomization of the [M] and [M-1] ions. In the case of the hydroxyindole-3-carboxylic acids, loss of H2O from the molecular ion is characteristic of the 4-isomer but initial loss of •OH from the molecular ion is the most important reaction of the other three isomers.
Quelques imino-4 thiophènes particulièrement stables
Authors: Laliberté Réal , Médawar Georges
Published: May 2006

Reaction between sodium salts of 3-amino-2-cyano-3-mercapto acrylhydrazides and two halocompounds resulted in the formation of some 4-iminothiophenes that were found to be quite stable. Their i.r., u.v., and n.m.r. spectra are described here together with one of their tautomeric forms obtained after acetylation.
Sulfonyl Chloride Kinetics. Part III. Nucleophilic Interaction on the Transition State for 4-X-Benzenesulfonyl Chloride Solvolyses
Authors: Rossall B. , Robertson R. E.
Published: May 2006

The kinetic solvent isotope effect [Formula: see text], was measured for 4-X-benzenesulfonyl chlorides (where X = MeO, Me, H, Br, and NO2) and shown to vary systematically, giving linear correlations with Hammett σ values and with [Formula: see text] ratios. These results contrast with the lack of sensitivity in k.s.i.e. to structural changes for displacement from a saturated carbon atom. This behavior is attributed to a greater degree of bond making required to achieve a critical charge on the chloride of the sulfonyl chloride at the transition state.
The Adsorption of Tetrachloroethylene and Trichlorofluoromethane on Anhydrous Nickel Sulfate
Authors: Klnloch G. A. , Machin W. D.
Published: May 2006

Several anomalous features of the adsorption isotherms obtained with tetrachloroethylene and trichlorofluoromethane on anhydrous nickel sulfate at 20.0, 5.8, and −7.5 °C, have been explained using a parallel plate pore model. Application of the Kelvin equation to the system indicates that adsorption hysteresis is due primarily to contact angle hysteresis, and that the thickness of the adsorbed layer that does not participate in meniscus formation is independent of relative pressure. Heats of immersion calculated from the estimated contact angles, and from heats of adsorption, have provided some support for the model.
Oxygen Interchange on Vanadium Oxide Catalysts
Authors: Mann R. F.
Published: May 2006

It is often difficult to compare results for heterogeneous reactions as the data reported in the literature are presented in. various ways. A common example of this difficulty is the reporting of oxygen adsorption rate constants in units such as 1 (g-catalyst)−1 s−1, 1 m−2 h−1, g m−2 h−1, g-mol m−2 h−1, etc. In this paper a number of studies involving oxygen interchange with vanadium pentoxide or vanadium pentoxide – potassium sulfate promoted catalysts are re-examined. Where possible, a first-order oxygen adsorption rate constant is evaluated from published data on rates of oxidation and rates of isotopic exchange, and expressed in units of 1 h−1 m−2 of catalyst surface. The rate constants so evaluated and compared as to catalyst composition, temperature, and activation energy show reasonable agreement, even though a variety of catalysts, processes, and techniques are involved.
Synthesis of p-O-(Tetra-O-acetyl-α-D-glucopyranosyl)-penicillin G
Authors: Nagabhushan T. L. , Chin C. G.
Published: May 2006

not available
Stereochemistry of Hexahydrocarbazoles; the Temperature-dependent Nuclear Magnetic Resonance Spectra of N-Acetyl Derivatives
Authors: McLean Stewart , Trotz U. O. , MacDonald C. J. , Reynolds W. F. , Wood D. J.
Published: May 2006

The configuration of certain substituted hexahydrocarbazoles 2, of significance in connection with earlier work, has been established. A study of the temperature dependence of the n.m.r. spectra of N-acetyl derivatives, initiated with the intention of distinguishing between cis- and trans-fused isomers, has led to the conclusion that the distinction could not be made on this basis since all of the temperature-dependent phenomena, even in cases where the cis-fusion had been established by other means, could be associated with rotational isomerism of the N-acetyl group and no observable effects in the temperature range studied could be related to conformational mobility of the ring system. Nevertheless, the results obtained provide information of value and interest regarding the stereochemistry of hexahydrocarbazoles.
1,3-Substituted Benzocycloheptanes
Authors: Doyle Terrence W.
Published: May 2006

We describe some derivatives of benzocycloheptan-1-one-3-carboxylic acid (2) which was obtained by reduction of benzo[6,7]cyclohepta-3,6-dien-1-one-3-carboxylic acid (1).
On the Isolation of (+)3-Thujone
Authors: Hach V. , Lockhart R. W. , Mcdonald Elizabeth C. , Cartlidge D. M.
Published: May 2006

Conditions necessary for the formation of the (+)3-thujone bisulfite adduct 1a and its utilization for the isolation of pure (+)-thujone have been established.
The Trifluoroacetic Acid Solvent System. Part I. Bases
Authors: Harriss M. G. , Milne J. B.
Published: May 2006

Electrical conductivity has been used to study the ionic behavior of several simple solutes in 100% trifluoroacetic acid. Fuoss extrapolations have been used to evaluate the limiting equivalent conductivities and association constants of the ammonium and alkali metal trifluoroacetates. The dependence of ionic mobility upon cation radius is different from that in water and other solvents and suggests that solvation is much less important in 100% trifluoroacetic acid. On the basis of these results, a proton transfer mechanism of conductance for the trifluoroacetate ion appears unlikely.
Complex Rearrangements of the Dimer of 3-Hydroxy-2,3-dimethylindolenine
Authors: Dave Vinod , Warnhoff E. W.
Published: May 2006

In the presence of acid the dimer 1 of 3-hydroxy-2,3-dimethylindolenine rearranges to 4, and then via 6 to 7a which is cleaved to 2,3-dimethylindole (2) and 2-formyl-3-methylindole (3). If peroxides and oxygen are not excluded, two other products, 13 and 30, are also formed. A rationalization of these reactions is offered which takes into account subtle differences in migratory aptitudes.
Temperature Dependence of the Diffusion of 1,2-Dichloroethane, 1,1,1-Trichloroethane, Trichloroethylene, and Tetrachloroethylene in Air
Authors: Watts Harry
Published: May 2006

The diffusion coefficients in air of 1,1-dichloroethane, 1,1,1-trichloroethane, trichloroethylene, and tetrachloroethylene have been measured over a temperature range from room temperature to close to their boiling points by a rate of evaporation method.
Studies on the Ethylation of Nucleosides with Triethyloxonium Fluoroborate
Authors: Rajabalee F. J.-M. , Hanessian S.
Published: May 2006

Alkylation of inosine and adenosine triacetates with triethyloxonium fluoroborate leads to selective N-ethylation. Inosine triacetate affords 7-ethylinosine as a major product, while adenosine triacetate is ethylated at the N-6 and -1 positions. Treatment with base affords the 6-ethyl analog by rearrangement.
A Semi-theoretical van der Waals Equation for Calculation of Vapor-Liquid Equilibria at High Pressures
Authors: Vera J. H. , Prausnitz J. M.
Published: May 2006

An equation of the van der Waals type is derived and applied to the calculation of vapor–liquid equilibria at elevated pressures. For the hard-sphere part of the equation the theoretical relation of Carnahan–Starling is used. The effect of intermolecular forces is represented by the usual van der Waals term but the "constant a" is permitted to vary with temperature and density as dictated by the experimental PVT data for argon; this variation of the "constant a" is generalized for other simple fluids through corresponding states. While this treatment is of little interest for representing the configurational properties of pure fluids, it is useful for calculating the properties of simple fluid mixtures. Illustrative vapor–liquid equilibrium calculations are performed for binary and ternary mixtures of nitrogen, argon, and oxygen at 6 and 18 atm.
Thermoelectric Studies of Silver Nitrate in Sodium Nitrate – Potassium Nitrate Eutectic Melt
Authors: Boxall L. G. , Johnson K. E.
Published: May 2006

The Seebeck coefficient, εT, of the thermocell Ag(T)/AgNO3 in NaNO3 − KNO3/Ag (T + ΔT) was measured as a function of silver nitrate concentration and temperature. Extrapolation of the results to unit mole fraction, N, of AgNO3 gave the value εT0 = − 277.5 − 0.136T °C (µV deg−1).For several mixed melts of AgNO3 and an alkali nitrate the function [Formula: see text] was calculated and shown to be linear in N. P was extrapolated to finite values for the pure alkali nitrates.
Reaction of Xenon Difluoride with Organosilicon Compounds
Authors: Gibson J. A. , Janzen A. F.
Published: May 2006

The reaction of xenon difluoride in acetonitrile solution with some organosilicon compounds is reported.
Alkylammonium Ions: Chemical Shifts and Interactions with Solvent in Aqueous Acid Solutions
Authors: Edward J. T.
Published: May 2006

The difference between the chemical shifts of the α and β hydrogens of the mono-, di-, tri-, and tetra-ethylammonium ions changes as the concentration of the solvent sulfuric acid is increased from 0 to 94%. A tentative explanation based on hydration of the ions is presented.
Permeation of Electrolytically Generated Hydrogen and Tritium Atoms through Lead
Authors: Muju Bansi L. , Smith Frank R.
Published: May 2006

Radiochemical and electrochemical evidence is presented that electrochemically generated tritium and hydrogen atoms permeate through lead foil at measureable rates at room temperature. The permeation process is controlled by diffusion through the metal lattice, Fick's First Law being obeyed by both H and 3H atoms. Using earlier measurements of the diffusivity of H in Pb, H and 3H concentrations of 4 × 10−7 and 9 × 10−13 g-atom cm−3 are computed for a current density of 53 mA cm−2 at the Pb cathode surface.The overall hydrogen-tritium separation factor, ST is apparently 0.3 ± 0.15, in contrast to Bockris and Srinivasan's 6.7 and 7.2 for cathodic gas evolution from acidic and alkaline media, respectively. Reasons are suggested for this large difference.
Steroidal Acetals of Formaldehyde
Authors: Herz J. E. , Lucero J. , Santoyo Yolanda , Waight E. S.
Published: May 2006

The anodic oxidation of cholesterol yields 3β,3′β-(methylenedioxy)-dicholest-5-ene. A new method for the preparation of methoxymethyl ethers of steroids is described. The n.m.r. and mass spectra of these compounds is reported.
The Removal of Oxide Impurities from Alkali Metal Fluoride Melts by Additions of Silver Halide
Authors: White Sydney H.
Published: May 2006

Electrochemical and chemical studies have shown that AgF and AgCl react quantitatively with oxide ions and hydroxide ions present as residual impurities in molten FLiNaK. This reaction offers a method for the simultaneous determination and removal of oxide containing impurities in fluoride melts.
Excess Thermodynamic Properties of Cyclopentane – Isomeric Decalin Systems at 25 °C
Authors: Jones D. E. G. , Weeks I. A. , Benson G. C.
Published: May 2006

Molar excess enthalpies and volumes of the systems cyclopentane – cis-decalin and cyclopentane – trans-decalin at 25 °C were determined by direct calorimetric and dilatometric measurements. Excess Gibbs free energies, also at 25 °C, were obtained from a study of the vapor–liquid equilibria. The excess properties of these cyclopentane systems are compared with those of their cyclohexane counterparts, and are interpreted in terms of the theory of Flory.
Crystal and Molecular Structure of 2-Bromo-11-ethyl-5,9-dimethoxytetracyclo[5.4.1.14,12•18,11]tetradecan-3-one, C18H27BrO3
Authors: Dunphy R. F. , Lynton H.
Published: May 2006

The molecular structure of 2-bromo-11-ethyl-5,9-dimethoxytetracyclo[5.4.1.14,12•18,11]tetradecan-3-one, C18H27BrO3, synthesized in an attempt to develop a method of conversion from an advanced relay compound to the alkaloid delphinine, has been determined by the heavy atom method. The compound crystallizes in the monoclinic system, space group P21/c, with unit cell dimensions a = 9.684(9), b = 13.481(15), c = 12.988(14) Å, β = 99.47(7)°, and four molecules in the unit cell. The atomic parameters were refined by block-diagonal least squares using anisotropic thermal parameters. The hydrogen atom positions were established but the parameters were not refined. The final agreement residual for 816 observed reflections is R = 0.044.The stereochemistry of the compound was found to be unsuitable for the delphinine synthesis.
The Dichloroiodine(III) and Dibromoiodine(III) Cations in Sulfuric Acid
Authors: Senior J. B. , Grover J. L.
Published: May 2006

The results of measurements of the conductivities and freezing points of solutions formed by adding chlorine or bromine to solutions of iodic acid and iodine (mole ratioI2/HIO3 = 2.0) in sulfuric acid are reported. The results provide evidence for the formation of the ions ICl2+ and IBr2+ in these solutions. Ultraviolet–visible spectra of the solutions are reported.
Solvent and Temperature Effects on Nitrogen Nuclear Spin Relaxation in Methyl Nitrate
Authors: Shepperd Christine M. , Schaefer T. , Goodwin B. W. , t'Raa J.
Published: May 2006

Analysis of the proton resonance line shape yields quadrupolar relaxation times for the nitrogen nucleus in methyl nitrate, both neat and in solution with 14 different solvents. Variable temperature studies lead to activation parameters for molecular reorientation in dimethylformamide and in cyclo-hexane. Factors influencing the rotational rate of the solute molecule are elucidated; the results are analyzed in terms of various models for the correlation time characteristic of rotation in the liquid. None are successful in predicting the observed differences between reorientational rates in polar and nonpolar solvents. The Debye–Stokes model is evidently applicable to the solution in the polar dimethylformamide but not to the solution in the nonpolar saturated hydrocarbons. In the latter the inertial model of Steele is more satisfactory. Other solvents fall between these two extremes.
Borane Adducts of Hydrazines and (Trifluoromethylphosphino) Hydrazines: a Nuclear Magnetic Resonance Study
Authors: Peterson L. K. , Wilson G. L.
Published: May 2006

Direct reactions between BX3 (X = Me, F, Cl) and the methylhydrazines MeNHNH2, Me2NNH2, Me2NNHMe, and Me2NNMe2 yield 1:1 adducts in ail cases except (a) BMe3 and Me2NNMe2, which do not react; (b) BCl3 and MeNHNH2, Me2NNH2 or Me2NNHMe, which result in hydrazinolysis of the B—Cl bond; and (c) BCl3 with Me2NNMe2, which yields a dark brown, viscous liquid. However, the unstable 1:1 adducts Me2NNH2BCl3 and Me2NNHMeBCl3 were prepared in solution, but were not isolated. On the basis of n.m.r. studies, it is concluded that adduct formation occurs at the more highly methylated nitrogen atom of Me2NNH2 and Me2NNHMe; for MeNHNH2, two isomeric adducts are formed with BF3, in a 5:1 molar ratio, corresponding to complexation at the methylated nitrogen, and at the unsubstituted nitrogen atoms, respectively. A similar study of adduct formation between BX3 and the trifluoromethylphosphinohydrazines (CF3)2PNMeNMe2, (CF3)2PNHNMe2, (CF3)2PNMeNH2, and (CF3)2PNHNHMe indicates that 1:1 adducts are formed in all cases except (d) BMe3 with (CF3)2-PNMeNMe2, for which no reaction was observed; and (e) BCl3 with (CF3)2PNMeNH2 and (CF3)2-PNHNHMe, for which elimination of (CF3)2PCl was observed. The adducts are volatile white solids, except (CF3)2PNMeNH2BMe3, which is a colorless liquid at room temperature, and (CF3)2PNMeNMe2BCl3, which is a non-volatile solid. In only one case was it possible to deduce an unambiguous stereo-chemistry for the adduct from n.m.r. data, viz. (CF3)2PNMeNH2BX3, (X = Me, F) where complexation occurs at the terminal, least substituted nitrogen atom. In (CF3)2PNMeNMe2BF3 and in (CF3)2-PNHNHMeBF3, the NMe and the NMe2 groups, and the PNH and NNH protons, respectively, are deshielded by the same, or very similar extents, so that an exclusive choice of structure cannot be made.
Synthesis and Reactivity of Halide Bridged, Cationic Complexes of Platinum and Palladium
Authors: Dixon K. R. , Hawke D. J.
Published: May 2006

The chloride bridged complex, [Pt2Cl2(PEt3)4][BF4]2,reacts with C2F4 and H2O or with aldehydes to yield trans-[PtCl(CO)(PEt3)2][BF4] and with HCOOH to cause catalytic decomposition of the acid to CO2 and H2. These reactions are of interest in mechanistic comparisons with other d8 complexes. Similar reactions of related platinum and palladium complexes are also described, together with the synthesis of the new complexes, [Pd2X2(PR3)4][BF4]2, where X = Br or I for R = phenyl and X = Br for R = ethyl, cw-[MCl(PEt3)2(Py)][BF4]and [MCl(PPh3)3][BF4] where M = Pd or Pt.
An Approach to Stereochemical Analysis by Ion Cyclotron Resonance. Distinguishing exo- and endo-Norborneol
Authors: Bursey Maurice M. , Hoffman Michael K.
Published: May 2006

The ion cyclotron resonance spectra of mixtures of biacetyl and exo- or endo-norborneol show differences in the acetylation of the alcohol by the m/e 129 ion formed from biacetyl. The differences may be interpreted as a difference by a factor of four in rates of acetylation; a steric effect is proposed as the cause of the difference.
The Effect of N-Substitution on the Rates of Saponification of Some Amino Acid Esters
Authors: Purdie Jocelyn E. , Benoiton N. Leo
Published: May 2006

The saponification rates (measured at 25 ° by a titrimetric method) of the unprotonated forms of the methyl esters of glycine, alanine, leucine, valine, and phenylalanine were compared with those of the N-methyl, the N-acetyl, and the N-acetyl, N-methylamino acid analogues. N-Acetylation slightly increased or decreased the rate but N-methylation caused a reduction by as much as a factor of ten, depending on the complexity of the side-chain. The esters of the N-acetyl, N-methylamino acids, which exist as cis and trans isomers, were saponified at rates intermediate between those of the esters of the N-acetylamino acids and N-methylamino acids. Activation parameters were obtained for the phenylalanine and leucine derivatives. N-Methylation resulted in an increase in ΔH≠ and ΔS≠ which was attributed in part to solvation effects. The hydrolysis of the cationic esters of glycine and alanine was still evident at pH 11.0. N-Methylation had little effect on the rates of saponification of the charged forms.
The Meyer Reaction of Phenylnitromethane in Acid. I. The Reactions of Phenyl-aci-nitromethane in Acid
Authors: Edward J. T. , Tremaine P. H.
Published: May 2006

Phenyl-aci-nitromethane reacts in aqueous sulfuric acid at room temperature to form phenylnitromethane and benzohydroxamic acid. The relative amounts of these two products depend on the concentration of the acid. Benzohydroxamic acid is formed by reaction of the intermediate, benzonitrile oxide, with water.Solvent effects, substituent effects, and isotope effects have been studied to determine mechanisms for these reactions of phenyl-aci-nitromethane.
Reactions of Amine Oxides and Hydroxylamines with Sulfur Dioxide
Authors: Edward J. T. , Whiting Josephine
Published: May 2006

Strychnine N-oxide (8; X = H) reacts with sulfur dioxide in benzene to form the sulfitoamine 9 (X = H), which rearranges in boiling water to the substituted sulfamic acid 10 (X = H) by a free-radical mechanism. The sulfamic acid 10 (X = H) is also formed by reaction of strychnine N-oxide with cold aqueous sulfur dioxide, and may be an intermediate in the reduction of the amine oxide by sulfur dioxide in hot water. With aqueous sulfur dioxide at 0°, N,N-dimethylbenzylamine N-oxide gives tertiary amine by reduction and secondary amine and aldehyde by a Polonovski-type reaction; however, N,N-dimethylaniline N-oxide gives tertiary amine, o- and p-dimethylaminobenzene sulfonic acids, but no appreciable amount of secondary amine. The sulfonic acids are probably formed by a free-radical mechanism, since their formation is largely suppressed by the addition of hydroquinone. The reactions of hydroxylamine and of β-phenylhydroxylamine with sulfur dioxide in water have also been studied.
An Electron Spin Resonance Study of the 9,10-Dihydrophenanthrene Radical Anion
Authors: Adam F. C.
Published: May 2006

The e.s.r. spectrum of 9,10-dihydrophenanthrene radical ion has been obtained in ether solvents at a number of temperatures between –106 and +51 °C. In dimethoxyethane–tetrahydrofuran mixtures below –80 °C, six triplet splittings are found with mean coupling constants of 5.36, 3.36, 2.66, 0.70, 0.26 and 0.15 oe. Above this temperature broadening occurs with some lines of the hyperfine spectrum due to motion resulting from the interconversion between the two equivalent conformers of the non-planar molecule ion. While the ring proton coupling constants are not strongly dependent on temperature, those due to the four methylene protons are, and interconversion between the conformers broadens the lines so that a 1:4:1 triplet is observed at low temperatures with a coupling of 2.97 oe. This is the sum of the axial and equatorial methylene proton splittings of a particular conformer. Near room temperature the motion is sufficiently rapid to give exchange narrowed lines and the process has an activation energy of 4.5 kcal/mol–1. From these observations it was possible to assign the coupling constants to specific protons in the molecule and to determine the dihedral angle between the rings as 21°.
Isomerization of 1-exo-4,5,67,8,8-Heptachloro-2,3-endo-epoxy-3a,4,7,7a-methanoindane with Base
Authors: Cochrane W. P. , Forbes M. A.
Published: May 2006

Treatment of the title compound, 2, with excess sodium methoxide produced an unsaturated secondary alcohol, 3. Structure elucidation was achieved by MnO2 oxidation followed by CrCl2 reductive dechlorination to give as the major product 2-oxa-4,5,6,7,8,8-hexachloro-3a,4,7,7a-tetrahydro-4,7-methanoindane.
Crystal Structure of cis-Dithiocyanatobis(1,10-phenanthroline)mercury(II), a Six-coordinate Mercury Complex
Authors: Beauchamp A. L. , Saperas B. , Rivest R.
Published: May 2006

cis-Dithiocyanatobis(1,10-phenanthroline)mercury(II) is a six-coordinate monomeric molecule with a distorted octahedral geometry.
Dimethylsulfoxidepentaammineruthenium(II) Hexafluorophosphate. A Spectroscopic Study
Authors: Senoff C. V. , Maslowsky Jr. E. , Goel R. G.
Published: May 2006

The infrared spectra of [Ru(NH3)5(CH3)2SO]X2, [Ru(ND3)5(CH3)2SO]X2, [Ru(NH3)5(CD3)2SO]X2, and [Ru(ND3)5(CD3)2SO]X2 where X = PF6− have been examined in detail between 4000–200 cm−1. These data, together with the 1H n.m.r. spectrum of [Ru(NH3)5(CH3)2SO](PF6)2 in D2O, suggest that dimethyl sulfoxide is bonded to ruthenium via the sulfur atom in spite of the fact that the νso frequency is not very different from that observed for uncoordinated dimethyl sulfoxide.
Radiation Chemistry of Dithionates
Authors: Murthy G. S. , Eager R. L. , McCallum K. J.
Published: May 2006

The salts Na2S2O6, Na2S2O6•2H2O, K2S2O6, BaS2O6, and BaS2O6•2H2O were irradiated at room temperature with 60Co gamma rays. When the irradiated salts were dissolved in water sulfite ions, sulfate ions, and acid were found as irradiation products. The dependence of yield upon absorbed dose was studied. The G-values found ranged from unity to 20. Thermal annealing of the irradiated salts had only a slight effect on product yields. For BaS2O6 there is a large increase in product yields after a dose of 28.3 × 1022 eV per mol has been absorbed. A mechanism involving SO3− and S2O6− radical ions is proposed.
Fermi Resonance of Infrared Vibrations in the —NH2 Groups of Polynucleotides
Authors: Zundel G. , Lubos W. D. , Kölkenbeck K.
Published: May 2006

The —NH2 group causes an intensive band pair in the i.r. spectra of DNA, r.RNA, poly (A + U), and poly (G + C). One band occurs at 3330, another at 3180 cm−1. This band pair is due to the NH stretching vibration of the hydrogen-bonded NH group as well as to the harmonic vibration of the —NH2 bending vibration, whereby these vibrations are coupled via Fermi resonance. This follows on comparison with papers on amines. The weak shoulder in the 3500–3400 cm−1 range is to be assigned to the stretching vibrations of the non hydrogen-bonded NH groups. The doublet structure disappears to a large extent in the denaturated DNA, since the strength of the Fermi resonance depends on the strength of the hydrogen bonds and the hydrogen bonds are of differing strength, due to the bending and stretching. The relative intensities of the two bands are interchanged in the corresponding band pair of the —ND2 groups, for which an explanation can also be given.