bluuebunny/crossref_metadata_2025 huggingface dataset:
Cationic platinum(II) complexes with acetylenes
Authors: Kong Pi-Chang , Theophanides T.
Published: May 2006

A new series of cationic platinum(II) acetylene complexes of the general formula [PtacenX]n+Y−n (with n = 1, 2), where X = Cl, Br, I, Y = Cl−, Br−, PtCl42−, PtBr42−,

[Formula: see text], and en = ethylenediamine, have been prepared. The infrared spectra of the complexes are discussed in relation to their structures and chemical properties. The effect of the anions on the infrared vibrations of the glycol and the ethylenediamine is also discussed.
Studies on Cd(OH)2 precipitated from various cadmium salt solutions
Authors: Srivastava O. K. , Secco E. A.
Published: May 2006

Infrared spectra and thermogravimetric (t.g.a.) and differential thermal (d.t.a.) analyses are reported for Cd(OH)2 obtained by the action of dilute ammonia solution on aqueous solutions of cadmium chloride, sulfate, and nitrate. The analyses indicate that the precipitated cadmium hydroxide from these solutions is often admixed with basic salts.
The alkaloids of Lycopodium alopecuroides L.
Authors: Ayer W. A. , Altenkirk B. , Valverde-Lopez S. , Douglas B. , Raffauf R. F. , Weisbach J. A.
Published: May 2006

The alkaloids of Lycopodium alopecuroides L. have been examined and seven alkaloids isolated. These include the known alkaloids lycopodine, lycodoline, and clavolonine, and three previously unreported alkaloids, alopecurine, debenzoylalopecurine, and alopecuridine. Anhydrolycodoline, previously obtained as a degradation product of lycodoline, was also isolated. The properties of the new alkaloids are described.
Preparation and base-catalyzed reactions of some β-halohydroperoxides
Authors: Kopecky Karl R. , Sande Johan H. van de , Mumford Cedric
Published: May 2006

The reaction between olefins, N-chloroacetamide or 1,3-dibromo-5,5-dimethylhydantoin, and hydrogen peroxide affords β-halohydroperoxides in good yields. These compounds react extremely rapidly in basic solution to give products which depend upon their structure. The 3-halo-2,3-dimethyl-2-butyl hydroperoxides form 2,3-dimethyl-3-hydroperoxy-1-butene and from the 2-halo-1,2-dimethylcyclohexyl hydroperoxides 1-methyl-2-methylene-cyclohexyl hydroperoxide is obtained. No allylic hydroperoxide can be detected from the reaction between base and 3-bromo-2-methyl-2-butyl hydroperoxide. Mainly cleavage products, acetone and acetaldehyde, are formed together with some 2,3-epoxy-2-methylbutane. The reaction between base and 2-bromo-1-phenylethyl hydroperoxide gives styrene oxide, benzoic acid, and some benzaldehyde. From trans-2-bromocyclohexyl hydroperoxide, trans-2-bromocyclohexanol, cyclohexene oxide, and some trans-1,2-cyclohexanediol are obtained upon reaction with base. No evidence for the formation of the allylic hydroperoxide was obtained.
Photochemical rearrangement and dimerization of 1,1-disubstituted indenes
Authors: McCullough John J.
Published: May 2006

The photochemical behavior of 1,1-diphenylindene and 1,1-dimethylindene has been studied. The former undergoes efficient rearrangement on direct irradiation or on acetophenone sensitization, forming 2,3-diphenylindene and 1,2-diphenylindene. In contrast, 1,1-dimethylindene gave no detectable products of methyl migration but formed dimeric cyclobutanes on sensitized and direct photolysis. The structures of the two dimers formed in the sensitized reaction were assigned from their nuclear magnetic resonance spectra. It was also demonstrated that hydrogen, like methyl, migrated inefficiently if at all in this system. This difference in migratory aptitudes is discussed in terms of orbital symmetry of the indene system.
Preparation of unsaturated carbohydrates. A facile synthesis of methyl 4,6-O-Benzylidene-D-hex-2-enopyranosides
Authors: Lemieux R. U. , Fraga E. , Watanabe K. A.
Published: May 2006

A simple method was explored for the preparation of methyl 4,6-O-benzylidene-hex-2-enopyranosides. Methyl 2,3-anhydro-4,6-O-benzylidene-D-hexopyranosides were converted to diaxial iodohydrins using sodium iodide in acetone which contained sodium acetate and acetic acid. Treatment of the iodohydrins with either methane- or p-toluenesulfonyl chloride in refluxing pyridine yielded the 2,3-unsaturated derivative in excellent yield. The four isomers for methyl 4,6-O-benzylidene-D-hex-2-enopyranoside were thus prepared. The rotations of the anomeric pairs followed Hudson's rules of isorotation. Evidence is provided that, in the absence of strong destabilizing interactions in the product, the epoxide ring of one of the above-mentioned 2,3-anhydroglycosides is opened by lithium iodide in ether to form the iodohydrin as the lithium alkoxide in high yield. This observation provides an explanation for the reduction of methyl 2,3-anhydro-4,6-O-benzylidene-α-D-allopyranoside to 4,6-O-benzylidene-D-allal. Reaction of methyl 4,6-O-benzylidene-2-deoxy-2-iodo-α-D-idopyranoside with methyl lithium provided 4,6-O-benzylidene-D-gulal. The conformational properties of a number of the compounds prepared and of acetylated methyl pentopyranosides, as derived from their nuclear magnetic resonance parameters, are discussed with particular reference to the role that geminal coupling constants may play in the determination of configuration and conformational equilibria.
Some observations on the ion–molecule reactions in ethylene
Authors: Myher J. J. , Harrison A. G.
Published: May 2006

The ion–molecule reactions in ethylene have been studied under conditions where C2H4+ was the only primary ion. In addition to the expected secondary ions C3H5+ and C4H7+, the C3H4+, C2H2+, and C2H3+ ions have been detected, presumably formed by the reactions[Formula: see text]Reactions [b] and [c] are endothermic for ground state reactants and it has been shown that the kinetic energy of the reactant ion plays a major role in determining the relative importance of these endothermic reactions.The C5H9+ ion has been shown to originate by further reaction of the C3H5+ secondary ion rather than by reaction of the (C4H8+)* collision complex. The reversion of the (C4H8+)* complex to reactants has been confirmed by the observation of isotopically mixed ethylene ions in C2H4–C2D4 mixtures.
Reflectance spectroscopic determination of cobalt, nickel, and copper with pyridine-2-aldehyde-2-quinolylhydrazone
Authors: Frei R. W. , Liiva R. , Ryan D. E.
Published: May 2006

Nickel, cobalt, and copper are separated from interfering metals by thin-layer chromatography on silica gel and cellulose layers. The metals are sprayed with pyridine-2-aldehyde-2-quinolylhydrazone solution and determined by diffuse reflectance spectroscopy. Under optimum conditions, 0.01 µg per spot can be determined easily and with good reproducibility.
Kinetic study of iridium(I) complexes as homogeneous hydrogenation catalysts
Authors: James B. R. , Memon N. A.
Published: May 2006

A study is described of the kinetics of reactions in which the complexes trans-IrX(CO)(PPh3)2, where X = Cl, Br, and I, are used for the catalytic homogeneous hydrogenation of olefinic bonds. Catalytic activity is enhanced in coordinating solvents such as dimethylacetamide. The rate law is complex, showing between zero and first order in each of iridium, substrate, and hydrogen concentrations, and the mechanisms proposed show the importance of a dissociation step in making available a coordination site on the transition metal complex. The dependence of rate on the halogen followed the order I > Br > Cl. Quite remarkably, traces of oxygen in the system enhance the hydrogenation rate considerably.
Infrared and Raman spectral studies of KNO2–KNO3 solutions
Authors: Brooker M. H. , Irish D. E.
Published: May 2006

Potassium nitrite frequently contains significant nitrate impurity, detectable by vibration spectroscopy. Analyses based independently on infrared and Raman band intensities permit a quantitative determination of the nitrate impurity. Reassignment of some previously reported vibrational frequencies is discussed.
Acid strengths of some substituted picric acids
Authors: Pearce P. J. , Simkins R. J. J.
Published: May 2006

The aqueous dissociation constants for a number of substituted picric acids and related compounds have been determined spectrophotometrically, and the values obtained correlated with the mid-equivalence potentials obtained by half-neutralization in acetone solution. Analysis of these results together with those obtained similarly for substituted benzoic acids shows that while the mid-equivalence potential method affords a rapid and convenient means of making a good estimate of the acid strength of a compound, it has its limitations and is only strictly applicable within the confines of a series of closely similar compounds. The observed pKa values of a large series of polysubstituted phenols were correlated with the predicted values obtained from the Hammett relation, and good agreement obtained, even with substituted picric acids; styphnic acids appear to behave anomalously.
Reaction between iodine and sodium bromate
Authors: King D. E. C. , Lister M. W.
Published: May 2006

The mechanism of the reaction: I2 + 2BrO3− → Br2 + 2IO3− in aqueous solution (pH 1.5 to 2.5) at 25 °C has been investigated. It is found to go in four stages. Firstly, there is an induction period during which the acidified bromate produces a catalyst (probably HOBr) for the next stage. However, iodide ions, if present, destroy this catalyst. Secondly, iodine reacts by the overall equation, I2 + BrO3− → IBr + IO3−, at a rate proportional to [H+]2[BrO3−]2. Thirdly, the iodine bromide reacts by the overall equation, 3IBr + 2BrO3− + 3H2O → 5Br− + 3IO3− + 6H+, at a rate proportional to [IBr]2[BrO3−]2. Finally bromide and bromate ions react to give bromine. Mechanisms are suggested for the various stages, and some of the rate constants are evaluated.
Calculations on the rate of photodissociation of hexafluoroacetone
Authors: Bowers P. G.
Published: May 2006

The dissociation of hexafluoroacetone from high vibrational levels of its first excited singlet state is treated by the methods of RRKM unimolecular theory. Predictions of the relative photodissociation rates for various exciting wavelengths are in reasonable accord with the observed rates and indicate a critical predissociation energy of about 6 kcal/mole. The calculated temperature dependence is less satisfactory and somewhat lower than the experimental variation.
Concerning the preparation of anhydrous hydrogen peroxide
Authors: Dove J. E. , Riddick J.
Published: May 2006

Preparation of pure anhydrous hydrogen peroxide has been attempted by a literature method which involves extraction of the aqueous solution with diethyl ether, followed by fractional distillation under vacuum. Mass spectrometric analysis shows that the product is seriously impure, and indicates that a reaction has occurred between the ether and hydrogen peroxide.
Vibrational energy transfer. Collisional quenching of competitive unimolecular reactions
Authors: Tardy D. C. , Larson C. W. , Rabinovitch B. S.
Published: May 2006

A technique is described for the study of collisional deexcitation of highly vibrationally excited polyatomic molecules by use of externally activated competitive unimolecular reaction systems. This method has some advantages and is illustrated by the decomposition of chemically activated hexyl-3 radicals in the presence of H2 and CF4 as heat bath molecules. The former removes ~1.2 kcal mole−1 per successful collision; while for the latter a value in excess of 4.6 kcal is found so that CF4 behaves operationally like a strong collider.
Hydrogen isotopic exchange in biphenylene and the preparation of biphenylene-d8
Authors: Lunelli Bruno , Pecile Cesare
Published: May 2006

The hydrogen isotopic exchange with basic and acidic agents has been widely investigated with the aim of preparing fully deuterated biphenylene. It has been noted that the very strong base KOD completely decomposes the hydrocarbon, while the strong base NaOD leads to random exchange, and the medium strength base Ca(OD)2 gives preferential exchange in α-position. Since the stability of biphenylene is less in acid mixtures than in basic ones, only acids of medium strength, which give preferential exchange in β-position, can be used.Good results in preparing fully deuterated biphenylene are obtained from two methods. The first of these consists of two exchanges which occur successively; one with an acid mixture and the other with a base. Both agents are of medium strength. The second method entails repeated exchanges with the strong base NaOD supported on Ca(OD)2. The latter method gives the highest isotopic purity and the best yield, as well as being much easier to carry out.
Hydrogenation of alkyl 2-oximino-α-D-arabino-hexopyranosides
Authors: Lemieux R. U. , Gunner S. W.
Published: May 2006

Hydrogenation of alkyl 2-oximino-α-D-arabino-hexopyranosides in the presence of palladium on charcoal and hydrochloric acid gave mixtures of the alkyl 2-amino-2-deoxy-α-D-hexopyranoside hydrochlorides with the gluco and manno configurations in about 90% yields. The fraction of gluco compound varied substantially with the nature of the alkyl group; viz., methyl, 71%; ethyl or n-propyl, 62%; isopropyl, 80%. More of the manno compound is formed, viz., isopropyl, 50%, when the 3,4,6-triacetate of the oximinoglycoside is hydrogenated. Hydrogenation of methyl 6-O-(2-oximino-α-D-arabino-hexopyranosyl)-β-D-glucopyranoside gave an about equimolar mixture of the two configurations.
Synthesis of 3,4,6-Tri-O-acetyl-2-oximino-α-D-hexopyranosides
Authors: Lemieux R. U. , Nagabhushan T. L. , Gunner S. W.
Published: May 2006

The reaction of the dimeric nitrosyl chloride adducts of tri-O-acetyl-D-glucal and tri-O-acetyl-D-galactal with alcohols and phenols in dimethylformamide at room temperature provides the corresponding tri-O-acetyl-2-oximino-α-D-hexopyranosides in good to excellent yields. The condensation can also be carried out in tetrahydrofuran in the presence of pyridine or simply in refluxing methylene chloride for the simple alkyl alcohols. The stereospecificity of the reaction is extreme; only products of one configuration for both glycosidic linkage and the oximino group were detected. This result is rationalized on the basis of a cis-configuration for a tri-O-acetyl-2-nitroso-D-glycal intermediate in the H1 half-chair conformation. The introduction of methyl groups on the carbon of the methoxy group of methyl α-D-glucopyranosides causes a progressive deshielding of the anomeric proton. The data indicate that isopropyl α-D-glycopyranosides avoid the orientation for the aglycon which has the anomeric hydrogen projecting between the two methyl groups of the aglycon. Methyl tri-O-acetyl-6-O-(tri-O-acetyl-2-oximino-α-D-arabino-hexopyranosyl)-β-D-glucopyranoside was prepared in 70% yield to illustrate the use of the method for the preparation of an α-linked disaccharide.
Kinetics of the chromic acid oxidation of alcohols in aqueous acetone solutions
Authors: Lee Donald G. , Downey William L. , Maass R. Michael
Published: May 2006

The rate law for oxidation of 2-propanol by chromic acid in aqueous acetone solutions has been found to be V = k3 [Cr(VI)| [2-propanol]ho, with the magnitude of k3 being over 700 times as great in 93.3% acetone as it is in water. In other respects (primary deuterium isotope effect, Hammett "rho" value, and salt effects) the general features of the reaction strongly resemble those observed in aqueous acetic acid solutions.
Erratum: Desert plant constituents. II. Ocotillol: An intermediate in the oxidation of hydroxy isooctenyl side chains
Authors: Warnhoff E. W. , Halls C. M. M.
Published: May 2006

not available
Erratum: Mechanism of the ninhydrin reaction. II. Preparation and spectral properties of reaction products from primary aromatic amines and ninhydrin hydrate
Authors: Friedman Mendel
Published: May 2006

not available
Fixation of atmospheric nitrogen by ruthenium compounds
Authors: Allen A. D. , Bottomley F.
Published: May 2006

not available
Hg(63P1)-sensitized decomposition of HNCO vapor and HNCO–H2 mixtures; the reaction of hydrogen atoms with HNCO
Authors: Friswell N. J. , Back R. A.
Published: May 2006

The Hg(63P1)-sensitized decomposition of HNCO vapor has been briefly studied at 26 °C with HNCO pressures from about 3 to 30 Torr. The products detected were the same as in the direct photolysis, CO, N2, and H2. The quantum yield of CO was appreciably less than unity, compared with a value of 1.5 in the direct photolysis under similar conditions. From this and other observations it is tentatively concluded that a single primary process occurs:[Formula: see text]From a study of the mercury-photosensitized reactions in mixtures of HNCO with H2, it was concluded that hydrogen atoms react with HNCO to form CO but not N2. The initial step is probably addition to form NH2CO. From the competition between reaction [1] and the corresponding quenching by H2, the cross section for reaction [1] was estimated to be 2.3 times that of hydrogen.
Kinetics and mechanism of the ethylene reduction of rhodium (III) chloride in dimethylacetamide solution
Authors: James B. R. , Rempel G. L.
Published: May 2006

The kinetics of the ethylene reduction of rhodium(III) trichloride to a rhodium(I) ethylene complex in dimethylacetamide solution have been examined over a range of temperatures and of concentrations of rhodium(III), ethylene, hydrogen ion, and chloride ion. The results suggest that the reaction proceeds through an initial dissociation of a chloro rhodium(III) species. A resulting intermediate rhodium(III) ethylene complex decomposes to rhodium(I) which is stabilized by rapid reaction with further ethylene as an olefin complex.
Reactions of organotin compounds. VIII. The reactions of tin hydrides with perfluorovinyl silicon compounds
Authors: Akhtar M. , Clark H. C.
Published: May 2006

The reactions of trimethyltin hydride and dimethyltin dihydride with (CH3)3SiCF=CF2 and (CH3)2Si(CF=CF2)2 respectively have been investigated. Under thermal conditions, reaction led to organotin fluorides and fluorovinyl-silanes. However, under ultraviolet irradiation at 25°, addition products were isolated of which (CH3)3SiCFHCF2Sn(CH3)3 and (CH3)3SiCF[Sn(CH3)3]CF2H were fully characterized. Evidence is presented which shows that these addition products are formed by a free radical process and that their decomposition to organotin fluorides and fluorovinyl-silanes proceeds via a β-fluorine elimination. Spectroscopic data are presented for a number of new organo-silanes.
The preparation of C-1 and C-2 methylated acenaphthenes
Authors: Bosch A. , Brown R. K.
Published: May 2006

The syntheses of 1-methyl-, 1,1-dimethyl-, cis(?)-1,2-dimethyl-, 1,1,2-trimethyl-, and 1,1,2,2-tetramethylacenaphthene have been accomplished by standard reactions from the two compounds 1-acenaphthenone and 2-methyl-1-acenaphthenone. These two ketones were in turn obtained from 1-naphthaleneacetic acid.
The measurement of angles and distances in molecular models. II. A device for the benzene ring
Authors: ApSimon J. W.
Published: May 2006

A measuring device which is useful for attachment to the benzene ring unit of Dreiding models and which could be useful for the location of distant groups is described.
Effects of additives on the e.s.r. of zinc oxide
Authors: Ueda Hisashi
Published: May 2006

Solutions of various organic compounds were mixed with zinc oxide powder. The mixtures of these compounds with zinc oxide were prepared by evaporating the solvent. When the zinc oxide with any of the additives is heated at 300 °C, two e.s.r. lines with g factors of 1.960 and 2.004, named l1 and l2, were observed. The intensities of l1 and l2 come to their equilibrium values after several minutes of heating. The results show that l1 and l2 are not from two independently existing species but from the two species R1 and R2, whose concentrations are connected with each other by some competitive equilibrium reactions. It was not possible to estimate the two equilibrium constants separately, but their product was estimated to be less than 2.5 × 10−8. R1 is concluded to be Zni+ (interstitial), while R2 may be Zn+ or (ZnOv)−(2v−1), where v is an integer. The compounds which gave strong l2 were naphthoquinones, naphthols, benzoquinone, hydroquinone, and anthraquinone, while the compounds which gave strong l1 were benzoin, anthrone, pyrene, and naphthalene.
A view of bond formation in terms of molecular charge distributions
Authors: Bader R. F. W. , Chandra A. K.
Published: May 2006

The process of bond formation as a function of internuclear separation for H2 and Li2 is interpreted in terms of the changes in the charge distributions and the forces which they exert on the nuclei. The charge distributions are calculated from extended Hartree–Fock wave functions which reduce to the Hartree–Fock atomic functions for infinite nuclear separation. The results for H2 indicate that at separations greater than 5 a.u. the net attractive force exerted on the approaching nuclei arises from a simultaneous inwards polarization of the atomic charge distributions. For separations less than 5 a.u. the nuclei are bound by the force exerted by the delocalized component of the charge distribution. The density distributions and forces for He2 over a range of internuclear separations are compared with those for H2 to contrast the formation of stable and unstable molecular species in terms of their respective charge distributions.The final section of the paper examines in detail the changes in the Hartree–Fock molecular charge distribution which arise from the inclusion of electron correlation in the wave function. The maximum error in the Hartree–Fock charge distribution for H2 is found to be in the region between the nuclei, where it overestimates the charge density by approximately 1%. The errors in the Hartree–Fock charge distribution for Li2 are found to be of the same order of magnitude as the uncertainty in the calculated density distribution itself.
Coordination of silicon tetrafluoride with alicyclic ethers and dimethyl ether
Authors: Guertin J. P. , Onyszchuk M.
Published: May 2006

Tensimetric titrations at −78° of silicon tetrafluoride with ethylene oxide, trimethylene oxide, tetrahydrofuran, tetrahydropyran, and dimethyl ether prove the formation of only 1:2 complexes, SiF4•2-(ether). All are unstable at 25° and either dissociate completely, as do SiF4•2(CH2)4O, SiF4•2(CH2)5O, and SiF4•2(CH3)2O, or decompose into SiF4 and a polymethylene oxide polymer, as do SiF4•2(CH2)2O and SiF4•2(CH2)3O. Silicon tetrafluoride does not coordinate with 1,4-dioxane in the range −94 to 25° and less than 1 atm pressure. Condensed phase heats of dissociation of SiF4•2(ether) complexes follow the order (CH2)3O > (CH2)4O > (CH2)5O ≥ (CH2)2O > (CH3)2O, which suggests that this is the relative order of basicities towards SiF4.
Preferential solvation of a polar solute by the polar group(s) in the solvents
Authors: Deb K. K.
Published: May 2006

The rotationally averaged values of the H—H coupling constants in various polar solvents corresponding to a wide range of overall dielectric constant are reported for 1,1,2-trichloroethane. Except for very few solvents, a smooth linear relationship between the observed H—H coupling constants and x ( = (ε − 1)/(2ε + 1)) of the solvents is demonstrated and the data are interpreted as evidence for preferential solvation of 1,1,2-trichloroethane by the polar group(s) in the solvents.
Erratum: Comparative formation constants for complexes of copper, nickel, and silver with some substituted pyridines
Authors: Sun M. S. , Brewer D. G.
Published: May 2006

not available
The photocycloaddition of nitrobenzene to alkenes
Authors: Charlton J. L. , Mayo P. de
Published: May 2006

The photochemical cycloaddition of nitrobenzene to cyclohexene at −70 °C gives an unstable crystalline adduct, an analogue of a molozonide, which has been characterized. Similar results have been obtained with norbornene, hex-1-ene, and 1-methylcyclohexene.
Sur la formation de l'endo et de l'exo acétyl-1 méthyl-6 bicyclo[3•1•0]hexane lors d'une réaction de Friedel–Crafts
Authors: Dufort Normand , Lafontaine Jacques
Published: May 2006

not available
The alkaline decomposition of o-phthalaldehyde di-p-toluenesulfonylhydrazone
Authors: Leznoff Clifford C.
Published: May 2006

The Bamford–Stevens reaction of o-phthalaldehyde di-p-toluenesulfonylhydrazone gives N-(3,4-dihydrophthalazinyl)p-tolylsulfone. The product is synthesized by an independent method.
Dimerization of Isoprene
Authors: Watanabe Shoji , Suga Kyoichi , Kamma Keizo , Torii Imako
Published: May 2006

The effect of solvents and various amines on the dimerization of isoprene with alkali-metal naphthalene, and the preparation of a new terpenic carboxylic acid, 4,8-dimethyl-3,7-nonadienic acid, by carboxylation of isoprene are described. Tetrahydrofuran, and the 50/50 (v/v) mixture of tetrahydrofuran and dimethyl sulfoxide each gave 40% of isoprene dimer. Sodium naphthalene in tetrahydrofuran solution containing a small amount of t-butylamine is active for the reductive dimerization of isoprene.
Organic and biological spectrochemical studies. XXVII. Electron spin resonance spectra of the pyrene monomer and dimer cation radicals
Authors: Cooper J. T. , Forbes W. F.
Published: May 2006

The electron spin resonance spectra of pyrene, dissolved in sulfur dioxide – boron trifluoride, are investigated. Two different spectra can be obtained, depending on the experimental conditions, and are ascribed to the monomeric and dimeric hydrocarbon radical cations.
Hydrolytic cleavage of cyclic allylic organoboranes
Authors: Sethi D. S. , Devaprabhakara D.
Published: May 2006

It has been shown that cyclic allylic organoborane intermediates obtained from monohydroboration of some 1,2- and 1,3-cyclic dienes with diborane generated in situ undergo slow hydrolysis with oxygen-free water to yield monoolefins.
Phase studies on the iron–selenium system
Authors: Dutrizac J. E. , Janjua M. B. I. , Toguri J. M.
Published: May 2006

The quasi-reduced iron–selenium phase diagram has been determined by a combination of differential thermal analysis, visual polythermal, and liquid sampling techniques. Iron and selenium form two compounds: FeSe2 with a broad stoichiometry range and FeSe2 with a much narrower composition field. The former compound was found to melt congruently at 1070 °C and 53.5 atomic % selenium, while the latter melted incongruently at 585 °C. Two liquid–liquid regions were observed in this system. One occurred above 790 °C from 73.9 atomic % selenium to about 99.92% selenium with a consolute temperature of 1070 °C at approximately 93 atomic % selenium. The other liquid–liquid region extends upwards from 1520 °C and lies between 3 and 39.5 atomic % selenium.
Trifluoromethyl-substituted fluorophosphates and fluoroarsenates
Authors: Chan S. S. , Willis C. J.
Published: May 2006

Synthetic routes have been developed to salts containing the anions [CF3PF5]−, [(CF3)2PF4]−, [(CF3)3PF3]−, [(CF3)2AsF4]−, and [(CF3)3AsF3]−. These are isolated as stable solids with Cs+, or sometimes Ag+, as the cation. Their 19F n.m.r. spectra are discussed, and it is suggested that the bis- and tris-(trifluoromethyl)-substituted fluorophosphates have a trans configuration.Trimethyltrifluoromethyltin, (CH3)3SnCF3, forms 1:1 complexes with PF5, (CF3)2PF3, and (CF3)3PF2. It is suggested that transfer of a trifluoromethyl group as CF3− has occurred here, leading to the formation of trimethyltin derivatives of the trifluoromethyl-substituted fluorophosphates.
Surface energy and surface tension
Authors: Flood E. A. , Benson G. C.
Published: May 2006

Some thermodynamic properties of surface regions are defined. The interdependence of these properties, the effects of particle size, etc. are examined.Results of computer summations of Lennard–Jones (6–12) interaction energies of atoms at lattice sites of face-centered cubic arrays are presented. "Shells" of lattice sites are described by reduced lattice vectors of constant magnitude. Such shells contain (1), 6, 8, 12,24, or 48 atoms.Sublimation energies of atoms in shells of clusters containing from 1 to 1337 atoms are compared with the sublimation energy per atom of an infinite cluster ε0. Mean sublimation energies of clusters of 13 and 1337 atoms are, respectively, about 0.36ε0 and 0.83ε0.Specific surface energies of clusters show relatively little variation with particle size; the specific surface energy of a cluster of 13 atoms is about 0.82 of the specific surface energies of clusters containing from 1337 → ∞ atoms.It is shown that two bulk phases and the interphase between them can grow in extent from suitable sources of mass, etc. while the nature and state of each of the three regions remain constant. Thus the extensive thermodynamic variables of each of the three regions can behave (mathematically) as homogeneous functions of first degree in one another. If the three regions consist of a single common component, under equilibrium conditions the Gibbs potentials per unit mass of the three regions must be the same. Accordingly if the Helmholtz potential of the surface region exceeds that of, say, the condensed bulk phase by As, per gram, the displacement mechanical growth potential, the pv potential per gram, must be less than that of the condensed bulk phase by As. If the pv potential of the bulk phase is zero, then As + (pv = 0 and for a flat interface As = γσ where γ is the surface tension and a the area per gram of the flat surface region.The above ideas underlie Gibb's treatment of surface regions. Such treatments cannot be applied, literally, to systems consisting of only a few atoms or molecules. Thus surface tension in the sense of a negative tangential surface stress of relatively large magnitude is a property of systems of very many molecules (bulk systems) in a state of complete thermodynamic equilibrium.The surface energies of crystals of molecular dimensions are reasonably meaningful and are only a little less than those of laboratory scale crystals. However, the "surface tensions" of such crystals are largely meaningless. The magnitudes of any negative stresses in the surface regions of such minute crystals are probably very much less than those corresponding to the true surface tension of large crystals; further, the surface stresses of these minute crystals are not closely related to excess surface energies, excess surface Helmholtz free energies, etc.
Chélates du fer (III) avec des anions dicarboxylates
Authors: Deneux M. , Meilleur R. , Benoit R. L.
Published: May 2006

Complex formation between iron(III) and oxalate, malonate, succinate, glutarate, and acetate ions has been studied by potentiométric and spectrophotométric methods at 25 °C, ionic strength 0.52 ± 0.02, and [Formula: see text] and 0.1 M H+ concentrations. The acidity constants of the dicarboxylic acids and the formation constants of the monochelates of iron(III) have been determined. The stability order is as follows: [Formula: see text].
Nuclear spin–spin coupling constants; equilibrium and kinetic studies for fluoroberyllate complexes in solution
Authors: Feeney J. , Haque R. , Reeves L. W. , Yue C. P.
Published: May 2006

19F nuclear magnetic resonance signals of aqueous solutions containing beryllium and fluoride ions have been used to study the equilibrium and kinetic processes occurring. Detailed studies of line widths, intensities, chemical shifts, and coupling constants have been made. This leads to an equilibrium constant determination Kc = 8.0 ± 2.0 × 10−2 mole kg−1 for the dissociation reaction[Formula: see text]The line width studies show that in addition to the above reaction there is fluoride ion exchange involving all three species. Rate constants at 33 °C are: k1 = 23.8 (s−1), k−1 = 3 × 102 mole−1 s−1, k2 = 4.3 × 102 mole−1 s−1 (for F− ion exchange with BeF42−), k3 = 4.5 × 102 mole−1 s−1 (for F− ion exchange with BeF32−), k4 = 4.5 × 102 mole−1 s−1 (for F− ion exchange between BeF32− and BeF4−). These values are determined within a factor of three. The equilibrium constant Kc is independent of temperature in the range 2 to 50 °C. An entropy of reaction ~ −5 e.u. is indicated.Studies of BeF2 solutions show that at least two fluoroberyllate complexes are present and these are assigned as monomeric BeF2 and (BeF2)n. Values of coupling constants and line widths in the absence of exchange processes strongly suggest the structures BeF3(H2O)− and BeF2(2H2O) for the tri- and di-fluoride species.The reduced coupling constants jX−F in the isoelectronic series BeF42−, BF4−, CF4, and NF4+correlate with atomic number in the same manner as the series TeF6, SbF6−, and SnF62−. A change in sign of the coupling constant jX–F is suggested between NF4+, CF4, BF4− as a group and BeF42−. The variation of coupling constants j and |Ψ2ns(0)| with atomic number is presented for a wide range of elements. The question of the origin of the sign of the coupling in relation to the atomic number dependence is related to a recent theory of Pople and Santry (16).
Carbon-13 kinetic isotope effects. III. Temperature dependence of k12/k13 for 1-bromo-1-phenylethane alcoholysis
Authors: Bron Jan , Stothers J. B.
Published: May 2006

The temperature dependence of k12/k13 for methanolysis and ethanolysis at the α-carbon of 1-bromo-1-phenylethane has been determined over the ranges 25° and 45° respectively. It is found that the kinetic isotope effect increases with increasing temperature for these systems. This result offers support for earlier interpretations on the 13C fractionations measured previously and the data are considered in terms of the original Bigeleisen equation. The results indicate that primary kinetic 13C isotope effects may be useful for distinguishing between bimolecular and unimolecular substitution mechanisms.
Circular dichroism of the tetracyanonickelate(II) ion
Authors: Haines Roland A. , Smith Anthony A.
Published: May 2006

When [Ni(CN)4]2− is dissolved in optically active 1,2-propanediol, two circular dichroism bands are observed which can be attributed to electronic transitions in the complex. Based on previous molecular orbital calculations, the relative energy levels of the d orbitals have been determined as [Formula: see text]
Infrared emission from the N–I2 reaction flame
Authors: Phillips L. F.
Published: May 2006

The flame spectrum between 1 and 3 μ consists mainly of nitrogen first positive bands, plus the atomic iodine line at 1.315 μ. The intensity of the emission bands increases markedly when iodine is added.
Theory of the thermoelectric power of ionic crystals
Authors: Allnatt A. R. , Jacobs P. W. M.
Published: May 2006

A thermodynamic analysis of the interface between a metal and an ionic crystal is performed and a differential equation for the potential difference Φ between the electrode and the crystal is derived. This equation can be used to give a new expression for the heterogeneous contribution to the thermoelectric power of an ionic crystal MX between electrodes M′. Addition of the homogeneous contribution gives the total thermoelectric power θ. A complete a priori evaluation of this expression for θ is only possible by making assumptions about the contribution to the potential difference between the surface and bulk of the crystal, φS – φB, which comes from the relaxation of cations and anions in the surface layers of an ionic crystal. Some information on this point is provided by the marked decrease in θ which occurs at low temperatures. While an analysis of experimental data in terms of the theory provides acceptable values for the ionic heats of transport, there is, as yet, no explanation of the remarkable Λ-point in the thermoelectric power of pure KCl.
Electric moments and conformation of substituted fluoroformates in benzene solutions
Authors: Bock E. , Iwacha D. , Hutton H. , Queen A.
Published: May 2006

The dipole moments of methyl-, ethyl-, n-propyl-, n-butyl-, n-amyl-, and phenyl-fluoroformate were determined in dilute benzene solutions at 25 °C. The experimental results suggest that the conformation of the fiuoro-esters is similar to the conformation of the chloro-esters and differs from the conformation of the normal esters; viz. the ester hydrocarbon group and the fluorine atom are cis to each other. Results of fluorine and proton n.m.r. measurements on these molecules support the conclusions based on the dipole moment data if a "through-space" coupling mechanism is assumed for the long range spin–spin coupling JH–F1−5.
Kinetics of some substitution reactions of the Group VI metal carbonyl halides
Authors: Allen. A. D. , Barrett P. F.
Published: May 2006

The kinetics in diglyme are reported for the two reactions of [Et4N][M(CO)5X] with aryl phosphines to form cis-[Et4N][PR3M(CO)4X] and PR3M(CO)5 where M = Cr, Mo, or W, X = Cl, Br, or I, and [Formula: see text] (p-FC6H4)3P, or (p-ClC6H4)3P. The reactions of cis-[Et4N][PR3M(CO)4X] with excess phos-phine to form (PR3)2M(CO)4 have also been studied kinetically. Possible mechanisms for these three types of reactions are discussed.
Cumulative yields in the 14-MeV neutron fission of 238U
Authors: Gorman D. J. , Tomlinson R. H.
Published: May 2006

The isotopic abundances of the elements xenon, krypton, and cesium formed in the 14-MeV neutron fission of 238U have been measured mass spectrometrically. The relative yields of some isotopes of krypton, strontium, zirconium, molybdenum, ruthenium, iodine, xenon, barium, cerium, and neodymium were measured using a Ge(Li) detector. The ratios were normalized through isobaric nuclides, and absolute yields were obtained by normalizing the sum of the heavy-mass yields to 100%.The results indicate that the fine structure persists at this excitation energy. In particular, the peak at A = 134 which is so characteristic of thermal fission is still prominent in 14-MeV fission.
Dielectric and nuclear magnetic resonance study of the hydrate of sulphur hexafluoride
Authors: Majid Y. A. , Garg S. K. , Davidson D. W.
Published: May 2006

In its dielectric and proton magnetic resonance behavior (except T1) the clathrate hydrate of SF6 is similar to ice I. Reorientation of water molecules appears to be little affected by the guest SF6 molecules and probably depends on the diffusion of rotational Bjerrum defects formed in numbers intrinsic to the lattice structure. The Arrhenius energy and activation entropy for dielectric relaxation are 12.3 + 0.5 kcal mole−1 and 6.8 + 2.0 cal deg−1 mole−1, respectively. The proton rigid-lattice second moment is 32.8 ± 0.5 G2 at −180 °C. The 19F second moment agrees with the value calculated for rapid isotropic rotation of SF6 molecules in the large cages only. Diffusion of water molecules in the hydrate is slower than in ice, which suggests that diffusion in ice occurs by migration of interstitial molecules through the channels in ice rather than by migration of lattice vacancies.
Studies on the surface area of zeolites, as determined by physical adsorption and X-ray crystallography
Authors: Yates D. J. C.
Published: May 2006

The determination of the surface areas of zeolites is discussed. It is shown that it is incorrect to use the multilayer isotherm method of Brunauer, Emmett, and Teller for solids where only little more than one monolayer can be adsorbed, in cavities little larger than the adsorbed molecules. The areas of such materials can, however, be determined from the beginning of the linear portion of their isotherms (point B). In addition, X-ray spectra can provide an independent method of measuring changes in the surface areas of zeolites.
Mass spectra of some deuterated ethanes. I. The effect of ionizing voltage
Authors: Amenomiya Y. , Pottie R. F.
Published: May 2006

The mass spectra of seven ethanes (d0–d6) have been obtained at various ionizing voltages. For low ionizing voltages (i.v. < 13.4 V), the only remaining ions are the parent molecule ion and that resulting from the loss of two hydrogen atoms (m/e 30 and m/e 28 in C2H6). With the exception of C2H5D, the ratio of the ion currents for these species remained reasonably constant below i.v. = 13.0. The sensitivity for detection of the molecule ion was found to decrease continuously as the D atom content was increased, both for high (70 V) and for low (12.8 V) ionizing voltages.
Potential parameters and surface areas from third-order gas–solid interactions
Authors: Wolfe. Robert. , Sams John. R.
Published: May 2006

Values of the effective interaction potential between a pair of adsorbed molecules are evaluated in terms of different potential models for argon adsorbed on two carbon surfaces. The resultant three-body (admolecule–admolecule–solid) energies are not in accord with independent theoretical predictions. It is suggested that the results may be indicative of a saturation phenomenon. The apparent areas of both powders are nearly independent of the assumed interaction model, a fact which lends weight to the quantitative significance of surface areas determined by this method.
Electron spin resonance studies of radiation damage. Part II. Gamma-irradiated single crystals of sodium chlorate: The ClO3 radical
Authors: Patrick P. F. , Sargent F. P.
Published: May 2006

Single crystals of sodium chlorate were gamma irradiated and examined by e.s.r. at −196 °C. One of the species present was identified as ClO3.
Erratum: Sur quelques réactions acide–base dans les solvants fortement basiques anhydres. I. Ethylènediamine
Authors: Heumann W. R. , Bouchard A. , Tremblay G.
Published: May 2006

not available
Etude de quelques dérivés Δ4-cyclohexèniques
Authors: Brown G. M. , Dubreuil P. , Demers E. P.
Published: May 2006

not available
Acyl derivatives of Hydroxylamine. XIII. Configuration and conformation of hydroxamic acid derivatives containing sulfur
Authors: Exner O. , Benn M. H. , Willis Frances
Published: May 2006

The configurations and conformations of S-methyl benzothiohydroxamic acid (3) and its S-oxo and S,S-dioxo derivatives (5) and (7) were established by means of a graphical comparison of their dipole moments with those of the corresponding p-nitro compounds.The proton magnetic resonance and infrared spectra of these compounds were also studied.It is concluded that the relative stability of stereoisomers in the series of compounds C6H5C(NOH)X seems to depend more on the electronic nature of the group X than on its steric requirements.
Structure of pithecolobine. II
Authors: Wiesner K. , MacDonald D. M. , Bankiewicz C. , Orr D. E.
Published: May 2006

The alkaloid of Samanea saman Merr. Pithecolobine is shown to be a family of closely related analogues of the general formula (13). The structure (9a) has been proved for one of these compounds.
Degradation of wood constituents during the self-agglomeration of an oak sawdust. II. Infrared study of two lignins
Authors: Naveau Henry P.
Published: May 2006

Structural changes in lignins isolated from particle-boards are studied by infrared spectrophotometry, in relation to an endothermic trend which characterizes the self-agglomeration process.Changes in intensity of various infrared bands are reported and are attributed to the following: (a) variation in the nature and distribution of substituents of the aromatic ring and conjugation of the aromatic ring with carbonyl C=O or C=C, which indicate an increasing state of condensation of the lignin, (b) simultaneous division of the macromolecule of lignin, partially caused by breakage of ether linkages between its lateral chains, (c) cleavage of bonds between lignin and carbohydrate material, and (d) insolubilization, with the acid lignin, of an increasing amount of carbohydrate material which is also increasingly condensed.The origin of the endothermic trend cannot be explained in terms of these reactions of lignin.
The X-radiolysis of water vapor containing methanol. Effects of some electron and hydrogen atom scavengers
Authors: Dixon R. S. , Bailey M. G.
Published: May 2006

The X-radiolysis of water vapor containing methanol at 125 °C and 1 atm pressure has been studied alone and in the presence of some electron and hydrogen atom scavengers. In water vapor containing methanol only, a plateau value G(H2) = 7.9 ± 0.3 is obtained at all methanol concentrations above 0.5 mole %. Addition of propylene drastically reduces this yield due to efficient scavenging of hydrogen atoms, and values for the total number of H atoms from all precursors g(H)t = 7,5 ± 0.2 and [Formula: see text] are deduced from the competition. An unscavengeable hydrogen yield g(H2) ~ 0.5 is also indicated in mixtures containing propylene. Nitrous oxide and sulfur hexafluoride are found to scavenge electrons efficiently in water vapor containing methanol and the number of hydrogen atoms arising from electron–positive ion recombination is estimated to have a value G = 2.2 ± 0.6. The number of hydrogen atoms arising from processes not involving electrons is g(H) = 5.2 ± 0.3. Carbon tetrachloride reacts efficiently with both electrons and hydrogen atoms, with k(H + CH3OH)/k(H + CCl4) = 0.085. Values of g(H) = 4.9 ± 0.5 and g(H2) = 0.8 ± 0.2 are deduced from mixtures containing carbon tetrachloride.
Accurate heats of atomization and accurate bond lengths.: I. Benzenoid hydrocarbons
Authors: Lo Donald H. , Whitehead M. A.
Published: May 2006

A semi-empirical P.P.P. type s.c.f.m.o. method has been developed to calculate, with practical accuracy, heats of atomization (at 25 °C), bond lengths, and resonance energies of benzenoid hydrocarbons. Sigma bond energies Eσb are estimated simultaneously with the pi bond energies Eπb in this method. Self-consistent field bond lengths are obtained, by minimization of the total bond energy, Eσb + Eπb, with respect to each individual bond length. The empirical resonance energies are calculated and a new term, the stabilization energy per CC bond, is introduced.
Accurate heats of atomization and accurate bond lengths.: II. Polyenes and polyphenyls
Authors: Lo Donald H. , Whitehead M. A.
Published: May 2006

Accurate heats of atomization and bond lengths are calculated for several polyenes and polyphenyls, using the s.c.f.–l.c.a.o.–m.o. method described in Part I (1). Localization of π and σ bonds is found in the linear polyenes and in the diphenyl-substituted polyenes. The estimated stabilization energy per CC bond (SECC) gives a direct measure of the π electron conjugation and σ bond compression. Conjugation stabilization and steric hindrance are analyzed in 1,3-butadiene and biphenyl; the predicted geometries are in good agreement with experimental results. The minimum energy for any planar structure is found to be associated with the s.c.f. calculated bond lengths. The validity of pi bond order as a measure of molecular stability in the polyphenyls is discussed.
Nuclear magnetic resonance studies of ketone.BF3 complexes. I. Exchange reactions in methylene chloride solution
Authors: Gillespie R. J. , Hartman J. S.
Published: May 2006

1H and 19F n.m.r. studies of BF3 adducts of some simple methyl ketones in methylene chloride solution have led to the following conclusions. (1) Only 1:1 adducts are formed which are not appreciably dissociated. (2) The down-field shifts of the proton resonances caused by complexation with BF3 are essentially independent of the ketone and depend only on the distance of the proton from the carbonyl group. (3) BF3 exchange is rapid on the n.m.r. time scale at room temperature, but the exchange process can be slowed sufficiently by lowering the temperature that separate signals due to free and complexed species can be observed. (4) Collapse of the 10B−11B isotope shift with increasing temperature showed that a second chemical exchange process, which exchanges fluorine among boron atoms, occurs in addition to the process of rapid breaking and re-forming of donor–acceptor bonds. A possible mechanism for this fluorine scrambling reaction is discussed.