bluuebunny/crossref_metadata_2025 huggingface dataset:
Photo-initiated reactions of thiols and olefins. IV. Inhibition of butene-2 isomerization by butadiene-1,3
Authors: Graham D. M. , Soltys J. F.
Published: May 2006

The kinetics of inhibition of the thiyl radical catalyzed isomerization of cis-butene-2 has been investigated. The results yielded the value 6.9 × 107 l mole−1 s−1 for the rate constant for CH3S attack on butadiene. It is proposed that this technique could be generally useful in determining attack constants for conjugated olefins.
A rigorous, purely chemical structure proof for aconitine and delphinine
Authors: Wiesner K. , Kao Wen-ling , Jay Ernest W. K.
Published: May 2006

A reaction sequence is described which allows the conversion of the aconitine degradation product (8) to the previously synthesized compounds 9 and 10 (10), thus providing a complete chemical proof of structures for aconitine 2 and delphinine 1.
The existence of salts of the oxyfluoborate ion [BF3O]2−
Authors: Clark M. J. R. , Lynton H.
Published: May 2006

The soluble hydrated oxyfluoborates previously reported as "CuBF3O•5H2O" and "ZnBF3O•7H2O" are now believed to be the fluosilicates CuSiF6•4H2O and ZnSiF6•6H2O. The insoluble anhydrous oxyfluoborates of Sr, Ba, and Pb could not be prepared.
On the characteristic vibrations of the NH2 group
Authors: Cain B. R. , Freeman J. M. , Henshall T.
Published: May 2006

The group frequency factorization procedure developed by King and Crawford (1) for the reduction in size of a vibrational secular determinant, by factorizing from it those frequencies that are characteristic of a constituent group, and subsequently extended by us (2), has now been successfully applied to NH2 group vibrations.The method is exemplified by the skeletal vibrations of methylamine, for which satisfactory results are obtained on factorization from the secular determinant of frequencies that are characteristic of both NH2 and CH3 groups.
Effect of functional group conformation on the infrared spectra of some gem difunctional phenylethylene derivatives
Authors: Currie D. J. , Lough C. E. , McClusky F. K. , Holmes H. L.
Published: May 2006

Except for the benzalmalononitriles, two functional group stretching vibrations occur in the infrared (i.r.) spectra of the β,β-difunctional-styrenes with similar functional groups. For geometrically homogeneous compounds with dissimilar functional groups only one absorption band occurs for each functional group. The two bands for similar functional groups have been ascribed to S-cis- and S-trans-conformations of the carbonyl groups with respect to the ethylene and variation in the frequencies of each of these oriented carbonyls to rotation of the functional group or groups out of the plane of the ethylene by steric factors.Frequencies for ethylenic C—H out of plane deformation bands for β-monofunctional styrenes accorded with those already assigned to this vibration. A similar assignment could not be made for the difunctional analogues.
Large heterocyclic rings from carbohydrate precursors
Authors: Stoddart J. F. , Szarek W. A. , Jones J. K. N.
Published: May 2006

Periodate oxidation of cycloheptaamylose and cyclohexaamylose, followed by borohydride reduction and acetylation, yields 2s,4S,5R,7s,9S,10R,12s,14S,15R,17s,19S,20R,22s,24S,25R,27s,29S,30R,32s,34S,35R-heneicosaacetoxymethyl-1,3,6,8,11,13,16,18,21,23,26,28,31,33-tetradecaoxacyclopentatriacontane (2) and 2s,4S,5R,7s,9S,10R,12s,14S,15R,17s,19S,20R,22s,24S,25R,27s,29S,30R-octadecaacetoxymethyl-1,3,6,8,11,13,16,18,21,23,26,28-dodecaoxacyclotriacontane (5), respectively. Both molecules are achiral.
Reissert compound studies. XXI. Arylation reactions
Authors: Piccirilli Robert , Popp Frank D.
Published: May 2006

The anions derived from both the isoquinoline and the quinoline Reissert compounds have been arylated by use of nitro and dinitro arylhalides. p-Fluorobenzaldehyde reacts preferentially at the carbonyl group and does not lead to arylation.
Methyl "radicals" on doped silica gel surfaces
Authors: Casey E. J. , Grant C. W. M. , Gardner C. L.
Published: May 2006

Methyl radicals adsorbed on silica gels containing dopings of the semiconductor ZnO were investigated by electron spin resonance at 77 °K. In addition to the normal 4-line "a"-spectrum, with hyperfine splitting of 23.3 ± 0.2 G, a second broader 4-line spectrum "b" with splitting 18.8 ± 0.6 G appears. Variations in line intensity with extent of doping were measured. Disappearance of the b-spectrum when the doped gels were dried under hot oxygen was observed. Partial delocalization of the radical's free electron and mixing into the doped surface were clearly indicated.Satellites ("c") to the a-spectrum were observed and are discussed.
Crystal structure of Cd2P2O7
Authors: Calvo C. , Au P. K. L.
Published: May 2006

Cadmium pyrophosphate forms crystals having triclinic symmetry with the unit cell parameters a = 6.672(8) Å, b = 6.623(8) Å, c = 6.858(7) Å, α = 95.80(10)°, β = 115.38(8)°, and γ = 82.38(8)°. The space group is [Formula: see text] and there are two molecules per unit cell. The structure was refined by least squares methods using 1326 reflections. The pyrophosphate anion, P2O74−, has a bent P—O—P bond with a bond angle of 132° and with average inner and outer PO bond lengths of 1.62 and 1.51 Å, respectively. The cations are coordinated to five and six oxygen atoms with average cadmium–oxygen atom bond lengths of 2.33 and 2.31 Å, respectively. This pyrophosphate structure differs from that adopted by other divalent metal ions of small radius in that the ends of the anion are in a nearly eclipsed orientation but shows some similarity to those A2B2O7 compounds, where A has a large radius and B a small one.
Surface area of cesium perchlorate
Authors: Venkataramana P. , Krishnan V. R.
Published: May 2006

Specific surface area of cesium perchlorate has been determined by isotopic surface exchange, air-permeability, and microscopic methods. There is agreement between the values of specific surface area evaluated by air-permeability and microscopic methods. The results obtained by the isotopic surface exchange method are reproducible but are significantly greater than those obtained by the other methods, and the difference is attributed to the fact that while air-permeability and microscopic methods measure the external surface area, the surface exchange method measures the total surface area (external as well as internal) of solids.
Steroids and steroidases. VIII. Further data on the preferred conformations of the cycloheptane rings of A-homosteroidketones
Authors: Jones J. Bryan , Zander J. Malcolm
Published: May 2006

The data presented substantiate the conclusions reported previously (1) regarding the applicability of the Hendrickson (2, 3) cycloheptane-based conformational analytical procedure to A-homosteroid-ketones of the 5α- and 5β- androstane and estrane series. For such cycloheptanone derivatives (with no bulky substituents at C-1 to C-5 of ring A) the twist chair conformations with the carbonyl group in the axis of adjacent position appear to be 1–2 kcal mole−1 lower in strain energy than predicted from the direct Hendrickson analysis and of these two favored conformers, the former may well be marginally preferred in many cases.
Cinétique d'oxydation de la cyclohexanedione-1,2 par l'ion thallique
Authors: Favier R. , Zador M.
Published: May 2006

The kinetics of thallic ion oxidation of 1,2-cyclohexanedione in aqueous perchloric acid solutions lead to the rate expression[Formula: see text]The importance of traces of chloride ions has been shown. Rate constants and activation parameters has been determined and are discussed.
Diprotonation equilibria involving 4-hydroxyazobenzene and 4-hydroxyazobenzene-4′-sulfonic acid
Authors: Strachan W. M. J. , Dolenko A. , Buncel E.
Published: May 2006

4-Hydroxyazobenzene and 4-hydroxyazobenzene-4′-sulfonic acid, which are known to be protonated in dilute acid on the azo function, are shown through spectroscopic studies to undergo a second equilibrium protonation in the 100% H2S04 region. The pKa2 values are −10.2and −11.1 respectively. The spectral evidence suggests that with both substrates the second protonation occurs on the phenolic oxygen site, rather than on carbon.
Central nervous system depressants.XVI. Some newer hydantoins and thiohydantoins
Authors: Chandra Satish , Dandiya P. C.
Published: May 2006

The synthesis of hydantoin and thiohydantoin derivatives is described.
Etude spectroscopique des dérives du peroxyde d'hydrogène. II. L'oxalate perhydrate, Na2C2O4.H2O2
Authors: Arnau José L. , Giguère Paul A.
Published: May 2006

The vibrational spectra of the addition compound Na2C2O4.H2O2 show mutual exclusion of all the fundamentals in infrared (i.r.) and Raman. This feature is confirmed by a study of the partly deuterated compound. It agrees with the conclusion of a previous X-ray and nuclear magnetic resonance study that the hydrogen peroxide molecule in that crystal is planar and centrosymmetric. The two component molecules are held together by strong (9 kcal mole−1) hydrogen bonds. Some 20 lattice modes were detected in i.r. or Raman. For comparison purposes, the lattice spectra of anhydrous sodium oxalate were also investigated.
Determination of the dipole moments of some polar liquids dissolved in polar solvents
Authors: Rizk H. A. , Youssef N. , Grace H.
Published: May 2006

The application of a modified form of the Onsager equation at the condition of infinite dilution of a polar solute in a polar solvent leads to reasonable dipole moments for water, pyridine, acetone, tert-butyl alcohol, n-butyl alcohol, and β-octyl alcohol, except in the case of water in tert-butyl alcohol at 30 and 40 °C and the case of acetone in n-butyl alcohol at 30 to 50 °C. The initial decrease of the dielectric constant of solvent by addition of solute in each of these two cases is associated with a reduction in the Kirkwood g-factor of solute. In all 12 systems investigated, strong hydrogen bonding occurs between solute and solvent molecules and often between solvent molecules themselves. It is thought that this equation must fail when short-range interactions assume predominant importance, but why it works so well for those cases which are also strongly interacting systems is not clear.
Radiolysis of gaseous isobutylene by 60Co γ-rays. II. Irradiation of isotopic mixtures: iso-C4H8 + iso-C4D8
Authors: Herman J. A. , Collin G.
Published: May 2006

The radiolysis of the isotopic mixture: iso-C4H8 + iso-C4D8 shows that, at 48 Torr pressure, about 40% of isobutane is formed in an ion–molecule reaction between isobutyl ion and the monomer. Half of the propene produced in radiolysis is formed in ion–molecule reactions, the H− transfer reaction to C3H5+ ion being the most important process. Small fractions of CH4, C2H2, C2H4, allene, and propyne are also formed in ionic processes, but the main part results from unimolecular decomposition processes of the excited isobutylene.
Kinetics of the pyrolysis of n-butane
Authors: Torok John , Sandler Samuel
Published: May 2006

The thermal decomposition of n-butane was investigated at temperatures ranging from 330 to 420 °C. This extension of the temperature range for such studies was made possible by the use of a highly sensitive analytical system, consisting of a gas–liquid chromatograph equipped with a hydrogen-flame-ionization detector which permitted the determination of the major products of the reaction at reactant conversions as low as 0.0002%. At temperatures below 400 °C the reaction order was both temperature and pressure dependent, a lower order, approaching 0.5, being favored at lower temperatures and higher pressures. The contribution to the reaction mechanism of a chain-termination step consisting of the combination of 2 secondary butyl radicals explains the observed phenomena.
Direct photolysis of tetrafluoroethylene at 1849 Å
Authors: Dacey J. R. , Littler J. G. F.
Published: May 2006

The photolysis of C2F4 at 1849 Å gives the following products, whose quantum yields are strongly dependent on substrate pressure: C2F6, C2F2, cyclo-C4F8, cyclo-C3F6, C3F6, C3F8, and polymer.The primary photochemical reactions are tentatively identified, and involve double bond fission and fluorine molecule and fluorine atom elimination.
Semiconduction in charge-transfer complexes
Authors: Bhat S. N. , Rao C. N. R.
Published: May 2006

Electrical conductivities, electron spin resonance spectra, electronic spectra, and Seebeck coefficients of solid charge-transfer complexes of benzidine–iodine, p-phenylenediamine–iodine, and phenothiazine–iodine as well as two antimony chloride complexes of phenothiazine have been studied. The phenothiazine–I2 system shows change in sign of the majority charge carriers with the donor–acceptor ratio. The effect of ambient gases on the conductivities of a few donors, acceptors, and their complexes in the solid state have been examined. Seebeck coefficient measurements show that the conduction in TCNQ salts takes place by a hopping mechanism.
Spectral reflectance studies of some metal chelates in the adsorbed state
Authors: Frei R. W. , Zeitlin H.
Published: May 2006

Adsorption phenomena of a group of metal chelates of pyridine-2-aldehyde-2-quinolylhydrazone (PAQH) have been investigated. Formulas have been postulated for the chelates on the basis of ultraviolet and visible transmittance and reflectance spectra, ion exchange studies of charges, and chromatographic and temperature behavior. Shifts of spectra with varying adsorbents have been explained on the basis of the electronic polarization theory. Unusual behavior of the chelates has been observed on starch and cellulose and the existence of mixed ligand species due to interaction of adsorbents with the chelates has been suggested.
Binuclear copper(II) complexes of the tetradentate ligand 1,4-di(2′-pyridyl)aminophthalazine: some novel five-coordinate derivatives
Authors: Thompson L. K. , Chacko V. T. , Elvidge J. A. , Lever A. B. P. , Parish R. V.
Published: May 2006

Reaction of the title ligand (L) with copper salts leads to the formation of three principal series of compounds, LCu2X3(OH)•H2O (X = Cl, Br), LCu2(RCO2)3, and LCu2(RCO2)4, where RCO2 represents various aliphatic and aromatic carboxylate species. Magnetic data, electronic spectroscopic data both at room temperature and at −196 °C, infrared spectra, and microanalytical data are correlated to reveal that these complexes contain a binuclear copper-copper system in which the copper atoms are 5-coordinate and square pyramidal. Brief details are presented of an X-ray structural analysis of the chloride complex confirming the structure proposed.The ligand forms complexes both in its neutral form and in an anionic deprotonated form. The ultraviolet spectra of the complexes distinguish these modes of bonding. The electronic spectra are discussed in terms of the 5-coordinate square pyramidal copper chromophore deemed to be present. In the complex L2Cu, the copper atom has a trigonally distorted 6-coordinate environment with tridentate anionic ligand.
Studies of rhenium–carboxylate complexes. I. Tris(μ-i-butyrato)di(chlororhenium(III)) perrhenate
Authors: Calvo C. , Jayadevan N. C. , Lock C. J. L.
Published: May 2006

One of the compounds obtained by reacting rhenium(III) chloride with isobutyric acid while exposed to oxygen has been shown by single crystal X-ray diffraction to be tris(μ-i-butyrato)di(chlororhenium(III)) perrhenate. The crystals are monoclinic with lattice parameters a = 8.980(5) Å, b = 17.790(8) Å, c = 15.361(8) Å, and β = 114.4(1)°. The space group is P21/c and there are 4 formula units per cell. A total of 1729 independent reflections were examined and the structure was refined by full three dimensional least squares to an R value of 0.114. Two Re environments are found, one consisting of a dimer unit bridged by three carboxylate groups with a chlorine atom per rhenium and the other as a perrhenate group. This latter group, showing a mean Re—O distance of 1.74 Å, shares an oxygen atom with a Re in the dimer unit, and this Re—O bond length is 2.28 Å long. The structure consists of a packing of chains of alternate dimers and perrhenate groups running parallel to the c axis.
Anodic behavior of silver in alkaline solutions
Authors: Dignam M. J. , Barrett H. M. , Nagy G. D.
Published: May 2006

Data, covering a range of pH and temperature, were obtained for the anodic oxidation of electropolished silver and the results compared with electrodes which had undergone repeated oxidation and reduction cycles. The behavior of the electrode is, in the main, complex, showing, for example, autopotential cycling under certain galvanostatic conditions (∼3 μA/cm2, 25 °C, 0.7 N NaOH), the period of oscillation being about [Formula: see text]. Several other hitherto unreported phenomena were also observed. The main conclusions reached are (i) that 2 different mechanisms are involved in the anodic formation of Ag2O on silver electrodes in basic electrolytes resulting in 2 types of film, 1 mechanism involves a dissolution–precipitation process, the other possibly a direct interfacial reaction; (ii) that the reduction of anodically formed Ag2O films either electrochemically or in hydrogen at 800 °C leaves behind a highly porous layer of silver metal; and (iii) that the limiting Ag2O film thickness is probably determined by a diffusion process occurring within the film.
A low temperature phase of (NH4)2TeBr6
Authors: Das A. K. , Brown I. D.
Published: May 2006

X-Ray diffraction has shown the existence of a low temperature tetragonal phase of (NH4)2TeBr6 having space group P4/mnc(D4h6) with a = 7.501, c = 10.765 Å.
Anomeric deoxy and unsaturated methyl pentofuranosides and pentopyranosides
Authors: Lemieux R. U. , Watanabe K. A. , Pavia A. A.
Published: May 2006

Both the anomers for methyl 2,3-dideoxy-D-glycero-pent-2-enofuranoside were characterized and hydrogenated to the corresponding methyl 2,3-dideoxy-D-glycero-pentofuranosides. The similar compounds were prepared in the pyranoside ring form but in the L-glycero configuration. The anomeric forms for methyl 3-deoxy-L-erythro-pentopyranoside are reported together with a number of their derivatives of interest for the study of solvation effects on conformational equilibria (21). The molar rotations of the deoxy and unsaturated glycosides are discussed as are the conformational properties of the various compounds.
Steroids and steroidases. IX. Activation parameters and the mechanism of base- and enzyme-catalyzed isomerizations of androst-5-ene-3,17-dione. The nature of the active center of the Δ5 → Δ4-3-ketosteroid isomerase of Pseudomonas testosteroni
Authors: Jones J. Bryan , Wigfield Donald C.
Published: May 2006

Determination of the activation parameters for the acid-, base-, and enzyme-catalyzed isomerizations of androst-5-ene-3,17-dione has revealed that the facility of the enzymic process is mainly due to an extremely low enthalpy of activation of 5.0 kcal mole−1. Further circumstantial evidence regarding the nature of the reacting groups at the active center has also been obtained, and a mechanism of enzyme action is proposed employing tyrosine and histidine as the principal amino acids responsible for catalyzing the isomerization.
Infrared spectra of aqueous sodium benzoates and salicylates in the carboxyl-stretching region: chelation in aqueous sodium salicylates
Authors: Dunn G. E. , McDonald R. S.
Published: May 2006

Infrared spectra in the frequency region 1300–1760 cm−1 are reported for 41 substituted sodium benzoates and 10 substituted sodium salicylates in deuterium oxide solution, and for 9 substituted salicylic acids in chloroform and carbon tetrachloride solutions. Carboxylate stretching frequencies of benzoates and salicylates correlate poorly with substituent constants, but the asymmetric frequencies of benzoates and salicylates correlate well with each other, and the asymmetric frequencies of benzoates correlate well with the asymmetric frequencies of the corresponding nitrobenzenes. It is suggested that, among substituted aromatic compounds, group vibrations which couple with the ring vibrations may correlate well with similar vibrations of other groups, but not with coupled vibrations of different symmetry, uncoupled vibrations, or substituent constants. Chelation in chloroform solutions of salicylic acid dimers can be detected by its influence on substituent effects, but infrared spectra provide no good evidence for chelation in aqueous sodium salicylates.
Dielectric studies. Part XXV. Methoxy group rotation in anisole and three para-substituted anisoles
Authors: Farmer D. B. , Walker S.
Published: May 2006

The dielectric absorption at several microwave frequencies of anisole, p-methylanisole, and p-bromoanisole in the solvent p-xylene, and p-dimethoxybenzene in the solvent cyclohexane has been investigated at 4 to 6 temperatures. Anisole, p-methylanisole, and p-dimethoxybenzene were all found to relax mainly by methoxy group rotation, whereas the relaxation process in p-bromoanisole was very largely molecular relaxation. In the literature, considerable divergence exists for the analyses of the dielectric data of anisole and substituted anisoles into contributions from two relaxation times and the magnitude of the weight factors governing each relaxation process. Such divergencies have been explored and justifiable analyses established for these systems where the weight factors governing the relaxation processes are shown to be roughly of the same order as those estimated from group moment data. The weight factor for molecular relaxation in the pure liquid appears considerably greater than that for a dilute solution of it in a non-polar solvent.
Adsorption of gases on 4A synthetic zeolite
Authors: Harper R. J. , Stifel G. R. , Anderson R. B.
Published: May 2006

Equilibrium data are presented for the adsorption of permanent gases and C1 and C2 hydrocarbons on Linde 4A synthetic zeolite from 50 °C down to the boiling point of the adsorbate or to a temperature at which the rate was very slow. The Freundlich equation often fits isotherms accurately; however, these linear logarithmic plots seem to be only portions of a more general non-linear relationship. Generalized Polanyi plots did not yield a unique characteristic curve for individual adsorbates at different temperatures nor for groups of adsorbates; nevertheless, these plots are useful in estimating the relative strength of adsorption of gases. Ar, O2, CH4, and C2H6 were the least strongly adsorbed, followed in order of increasing strength by N2, CO, CO2, and C2H2. Ethylene was strongly but anomalously adsorbed. For the gases studied, the quadrupole moment seems to be the principal factor determining strong adsorption.
Infrared studies on rotational isomerism. IV. 2-Cyanoethanol
Authors: Schneider Michel , Giguère Paul A.
Published: May 2006

From the infrared spectra of the vapor measured between 4000 and 200 cm−1, 2-cyanoethanol was found to exist as gauche and trans isomers in roughly equal proportions around 100 °C. The gauche form is the more stable of the two, as in 2-chloro- and 2-bromo-ethanol, but the enthalpy difference is less than half as large; at most 0.7 kcal mole−1. This indicates some weak (about 1 kcal mole−1) intramolecular hydrogen bonding between the OH group and the π electrons of the C≡N bond.In the solid, two distinct crystalline phases have been observed. Crystal II, consisting of gauche molecules only, is normally obtained; for instance by annealing the vitreous solid from low temperature deposition of the vapor. Crystal I, which contains the two isomers, may be obtained irreversibly from the melt of crystal II under controlled conditions.On the other hand there was no indication in the spectra of a cyclic tautomer as suggested recently.
Mesure directe de la constante d'ionisation de l'ammoniac liquide entre −77 et −36 °C
Authors: Renaud Maurice
Published: May 2006

The ionization constant of liquid ammonia has been measured with a concentration cell between −77 and −36 °C. Between these temperatures, pK increased from 33.1 ± 0.3 at −36 °C to 37.8 ± 0.3 at −77 °C. These measured data confirm those calculated with thermodynamic values of liquid ammonia, ammonium ion, and amide ion. The formula pK = 9.0 + 5.7 (103/T) can represent the values of the pK of liquid ammonia for the studied temperatures.
Free radical halogenation of deuteriochloroform
Authors: Tanner Dennis D. , Mosher Melvyn W. , Bunce N. J.
Published: May 2006

The vapor phase chlorination and bromination of deuteriochloroform has been carried out in the presence of the corresponding hydrogen halide. The halogenations demonstrated the reversibility of the abstraction reaction by atomic bromine while the chlorination reactions failed to show any evidence for a reversible abstraction.
Rearrangement of the Diels–Alder adduct of azodibenzoyl and cyclopentadiene
Authors: Mackay Donald , Campbell J. A. , Jennison C. P. R.
Published: May 2006

The product of the thermal isomerization of the Diels–Alder adduct 1 of azodibenzoyl and cyclopentadiene has been identified by degradation and nuclear magnetic resonance analysis as the cis-bicyclic oxadiazine 2a, the dihydro derivative of which has been synthesized. The isomerization is quantitative and is first order throughout in solution in a range of solvents ; kinetic and other evidence point to it being a sigmatropic rearrangement.
Isotope effect studies on elimination reactions. VII. The stereochemistry of elimination from 2-phenylethylammonium ions
Authors: Bourns A. N. , Frosst A. C.
Published: May 2006

The stereochemistry of the base-promoted elimination reactions of 2-phenylethyltrimethylammonium and 2-phenylethyldimethylanilinium ions has been investigated using both ethoxide ion in ethanol and t-butoxide in t-butyl alcohol as base-solvent systems. The proton magnetic resonance spectroscopic analysis of the deuterated styrene products formed from the reactions of the threo-2-phenylethylammonium-1,2-d2 ions established that elimination proceeds more than 95% by an anti process.
Low frequency infrared and Raman spectra of the N,N,N′,N′-tetramethyl-ethylenediamine adducts of the Group IIb dihalides
Authors: Abraham M. H. , Parrett F. W.
Published: May 2006

A study of the low frequency vibrational spectra of the complexes MX2.TMED (where M = Zn, Cd, Hg; X = Cl, Br, I; TMED = N,N,N′,N′-tetramethylethylenediamine suggests that in the solid state the zinc and mercury complexes are 4-coordinated but the cadmium complexes are all based on octahedral halogen bridged structures. Assignments of the vibrational bands are discussed.
The dimethyl formamide – acyl halide complex. II. A synthesis of selected indole-3-aldehydes
Authors: Horning D. E. , Muchowski J. M.
Published: May 2006

The synthesis of selected indole-3-aldehydes from the corresponding indoles and the DMF – acyl halide complex is described.
Preparation of 2,7-polymethylene-4,5-benzotropylium perchlorates
Authors: Harmon Robert E. , Suder Robert , Gupta S. K.
Published: May 2006

The first synthesis of 2,7-polymethylene-4,5-benzotropylium perchlorates has been achieved by reduction of the carbonyl function in 2,7-polymethylene-4,5-benzotropones and subsequent treatment with perchloric acid.
Evidence for a ‘block-type’ structure in the main chain of the cell-wall mannan from Candida species PRL 1S20
Authors: Gorin P. A. J. , Spencer J. F. T.
Published: May 2006

Evidence for a ‘block-type’ structure involving α-(l→3)- and -(1→6)-D-mannopyranosyl units from the mannan in Candida species PRL 1S20 is presented.
Molecular size distributions in multichain polymers: application of polymer theory to silicate melts
Authors: Masson C. R. , Smith I. B. , Whiteway S. G.
Published: May 2006

Expressions developed previously by Flory and by the authors for molecular size distributions in branched polymers were used to derive theoretical curves of activity vs. composition in binary silicate melts. In contrast with curves based on the Flory distribution those derived from our result were in good agreement with experiment over the entire range of compositions up to the maximum degree of polymerization allowed by the theory. The comparison is illustrated for the systems PbO–SiO2 and SnO–SiO2.
The heat of formation of the norbornyl cation
Authors: Spencer H. , Mo Y. K.
Published: May 2006

The heat of formation of the norbornyl ion has been evaluated from experimental data. This was compared to the heats of formation of various formulations of the norbornyl ion computed by quantum mechanical methods.
Crystallographic studies of cobalt arsenates. IV. Crystal parameters of cobalt diarsenate
Authors: Ozog J. , Krishnamachari N. , Calvo C.
Published: May 2006

The crystal structure of cobalt diarsenate has been shown to be a new member of a series of structures closely related to that of the mineral thortveitite. The triclinic unit cell parameters are: a = 6.55 Å, b = 8.52 Å, c = 4.76 Å, α = 91.0°, β = 104.0°, γ = 91.3°. There are 2 molecules per unit cell with a symmetry Cl or [Formula: see text] and a measured density 5.01 g/cm3. The single crystal patterns show nearly the C2/m symmetry characteristic of the mineral thortveitite and its analogues.
Pulse radiolysis of nitric oxide in aqueous solution
Authors: Seddon W. A. , Young M. J.
Published: May 2006

Pulse radiolysis of aqueous solutions of nitric oxide at neutral pH shows that the reaction initiated by the hydrated electron, e−(aq), proceeds via NO− and a new transient thought to be (N2O2)−, and not HNO as indicated previously by steady state radiolysis.
Structure of didehydrochelidonine
Authors: Benn M. H. , Mitchell R. E.
Published: May 2006

not available
Mass spectrometric study of the thermal decomposition of dimanganese decacarbonyl and dicobalt octacarbonyl
Authors: Bidinosti D. R. , McIntyre N. S.
Published: May 2006

The free radicals •Mn(CO)5 and •Co(CO)4 have been produced by the pyrolysis of Mn2(CO)10 and Co2(CO)8 in graphite flow reactors. The effusing molecular beams from these reactors were analyzed mass spectrometrically. Evidence is presented for the following equilibria[Formula: see text]From the temperature dependence of the equilibrium constants, enthalpy changes of 24.9 ± 2 and 14.5 ± 2 kcal/mole, respectively, have been obtained. These enthalpy changes give D(Mn—Mn) = 21 ± 3 kcal/mole and D(Co—Co) = 13 ± 3 kcal/mole, which substantiate the earlier literature values based on electron impact measurements.
Electron spin resonance studies of oriented NO2 and NF2 in inert matrices at low temperatures
Authors: McDowell C. A. , Nakajima H. , Raghunathan P.
Published: May 2006

Preferentially oriented NO2 and NF2 in inert matrices have been studied in some detail by electron spin resonance methods at 4.2 °K. Methods are discussed which may optimize the degree of preferential orientation of the paramagnetic species in appropriate matrices. The results demonstrate that while neon is the best host matrix for orienting NO2, argon is to be preferred for NF2. The g-values and hyperfine splitting data have been accurately determined and are compared with earlier values. Motional processes are suggested to explain the spectra obtained for NF2 in an argon matrix in the temperature range 4–30 °K.
Microwave spectrum of paraldehyde
Authors: Kewley R.
Published: May 2006

The microwave spectrum of paraldehyde has been investigated in the range 14 to 26 GHz using commercial reagent grade samples. The spectrum of the symmetric rotor triequatorial methyl conformer was found, giving the value B0 = 1822.41 ± 0.05 MHz. he effects of low energy molecular vibrations are prominent in the spectrum.
Volumes of activation for the aquation of Co(NH3)5Cl2+ and Cr(NH3)5NCS2+ complex ions in solution
Authors: Gay D. L. , Nalepa Robert
Published: May 2006

The volumes of activation for the aquation of Co(NH3)5Cl2+ and Cr(NH3)5NCS2+ in aqueous acidic solution (0.1 M HClO4) have been measured and found to be −7.5 ± 1 and −8.6 ± 1 ml/mole, respectively. These values are more consistent with an SN1 than an SN2 pathway for the aquation of both of these complexes.
Proton magnetic resonance studies of ionic solvation in ion-exchange resins.: Part I. Sulfonated cation-exchange resins
Authors: Gough T. E. , Sharma H. D. , Subramanian N.
Published: May 2006

The proton magnetic resonance spectra of cation-exchange resins of crosslinkage X1 to X16 in the H+, Li+, Na+, K+, Rb+, Cs+, and NH4+forms have been recorded and the values of the molal chemical shift, δM+0, are found to be −0.321, −0.005, 0.041, 0.031, 0.028, 0.015, and 0.00 (assumed) p.p.m./mole, respectively, for the cations. These values are very nearly equal to those observed in corresponding aqueous solutions, indicating that ion–solvent interactions are similar in both the resin matrix and the aqueous solution. The temperature dependence of the chemical shift shows the same trend. The effective hydration numbers calculated from the temperature dependence are 2.0 (4.81 m) for the H+form, 4.8 (3.25 m) and 3.6 (5.26 m) for the Na+form, 4.4 (3.9 m) for the K+form, and 2.4 (6.18 m) for the Cs+form. The ions in the resin phase behave as solutions of strong electrolyte, which is consistent with the polyelectrolyte gel model for the ion-exchange resin.
Wavelength dependency of the relative proportions of singlet/triplet methylenes from the photolysis of diazomethane
Authors: Taylor G. W. , Simons J. W.
Published: May 2006

Results of a high pressure study of the photolysis of diazomethane/cis-butene-2/ethylene mixtures at 4358 and 3660 Å under various conditions are reported. These results indicate that the proportion of ground triplet state methylene radicals, produced in the primary photolysis of diazomethane, is independent of photolysis wavelength.
Kinetics of aquation of the fluoropentaamminecobalt(III) ion
Authors: Swaddle T. W. , Jones W. E.
Published: May 2006

The kinetics of the hydrogen-ion-independent pathway for the replacement of fluoride in aqueous (NH3)5CoF2+ by H2O have been reinvestigated using a specific fluoride-ion electrode, with due regard for the concomitant autocatalytic loss of the ammine ligands. In perchlorate media of ionic strength 0.1 M, the first-order rate coefficient is 1.22 × 10−6 s−1 at 45°, and the kinetics are represented by ΔH* = 24.4 kcal mole−1 and ΔS* = −9 cal deg−1 mole−1 over the range 35–75° at least. The relationship of these data to those for the aquation of other species of the type ML5Xn+ is discussed.
The effect of the cation on the 2Eg [Cr(CN)6]3− and 3T1g [Co(CN)6]3− emissions: a study of Ag3[CrxCo1−x(CN)6]
Authors: Kirk Alexander D. , Schläfer Hans L. , Ludi Andreas
Published: May 2006

The luminescence behavior of the compounds Ag3[CrxCo1−x(CN)6] has been found to differ in several respects from that of the related compounds K3[CrxCo1−x(CN)6]. In the silver compounds at room temperature, the Co(III) 3T1g emission is too weak to be seen; the Cr(III) 2Eg emission appears to be quenched to a greater extent, and is displaced about 1.5 kK to higher energy. At 77 °K, where the Co(III) 3T1g emission can be seen, it is found to be displaced about 0.5 kK to higher energy. These effects, and also the shifts of the [Cr(CN)6]3− and [Co(CN)6]3− absorption bands in the reflectance spectra of the compounds, are discussed on the basis of interaction of the Ag+ ion with the [Cr(CN)6]3− and [Co(CN)6]3− ions. Furthermore, the variation of Cr 2Eg emission intensity with mole percent Cr has its maximum at a lower Cr concentration in the silver salts, indicative of more extended interaction between Cr3+ ions than in the potassium salts.
Nuclear magnetic resonance studies. XX. Structures and 1H nuclear magnetic resonance parameters of the bromination products of some substituted bicyclo[2.2.2]octenes
Authors: Gurudata M. Gordon , Stothers J. B.
Published: May 2006

The stereochemical course of the reaction of some 7,8-dicarboxylate derivatives of 1,3,5,5-tetramethyl-bicyclo[2.2.2]oct-2-ene with bromine has been established. The proton magnetic resonance parameters of these products are discussed.
Solvation differences in the hydrolysis of certain alicyclic bromides
Authors: Golinkin H. S. , Parbhoo D. M. , Robertson R. E.
Published: May 2006

A detailed study of the hydrolysis in water of the cis and trans cyclopentyl and cyclohexyl bromohydrins reveals significant differences in the apparent heat capacity of activation (ΔCp≠). The cis isomers have values of[Formula: see text]; the same value as found for cyclopentyl bromide, but more negative by 10 caldeg−1 mole−1 than that found for the hydrolysis of cyclohexyl bromide. By contrast, the corresponding value for trans isomers was about −45 cal deg−1 mole−1. The differences in ΔCP≠ can be explained in terms of different mechanisms. Secondary β-deuterium isotope effects of 2.28 for the cis-2-bromocyclopentanol-1-d and 2.45 for cis-2-bromocyclohexanol-1-d confirm hydrogen participation in these cases. The corresponding ketones were the only products detected.
Partition coefficients and ultraviolet absorption maxima for the cinnamoyl derivatives of some long-chain and large-ring amines
Authors: Currie D. J. , Holmes H. L.
Published: May 2006

Partition coefficients of the title compounds in the system cyclohexane–water do not increase steadily with increasing chain length or ring size but level off to a limiting value. Reasons are advanced to account for this observation. Absorption maxima, on the other hand, are not influenced by the size of the ring or the length of the chain but are dependent only upon the degree of substitution on the amide nitrogen atom.
Signs of long-range amino proton – ring proton coupling constants in N-ethyl-4-chloro-2-nitroaniline
Authors: Schaefer T. , Wasylishen R.
Published: May 2006

In N-ethyl-4-chloro-2-nitroaniline there exists a measurable indirect spin–spin coupling constant of ±0.39 ± 0.03 Hz between the methylene protons and ring proton 6. The amino proton is coupled to ring protons 5 and 6 and also to the methylene protons. Consequently, although the amino proton resonance is broad due to incompletely relaxed coupling to 14N, normal multiple resonance experiments show that 5JmH,NH = 0.67 ± 0.03 Hz and 4JoH,NH = −0.35 ± 0.03 Hz.
Mechanism of the reaction of sarin with methanol in the presence of amines
Authors: Weinberger M. A. , Greenhalgh R. , Lutley P. M.
Published: May 2006

In pyridine or 2-methyl-2-propanol solution, the kinetics of the reaction of sarin with methanol in the presence of amines to produce the ester, methyl isopropyl methylphosphonate, is shown to be of first order with respect to each of the three components. By varying the amine it was deduced that the amine acts as a general base catalyst but the catalysis is subject to large steric effects.
Studies in isoxazole chemistry. III. The preparation and lithiation of 3,5-disubstituted isoxazoles
Authors: Micetich R. G. , Chin C. G.
Published: May 2006

3-Arylisoxazol-5-ones and 5-arylisoxazol-3-ones were prepared and converted to the N-methyl and O-methyl derivatives by reaction with diazomethane. The halogen in 3-phenyl-5-chloroisoxazole was replaced by several alkoxy and thioalkoxy groups. The 3,5-disubstituted isoxazoles thus obtained reacted with n-butyllithium to form the 4-lithio derivatives, as shown by conversion to 4-carboxylic acids and 4-iodocompounds. 3-Methoxy-5-phenylisothiazole was also lithiated at the 4-position.
Study of iron(II) complexes with halides and thiocyanate in acetonitrile
Authors: Kratochvil Byron , Long Robert
Published: May 2006

In acetonitrile, iron(II) forms stable 1:1 complexes with chloride, bromide, and iodide and both 1:1 and 1:2 complexes with thiocyanate. Stepwise formation constants for the complexes were determined spectrophotometrically by a mole-ratio method. The log K values are: FeCl+, 5.8; FeBr+, 5.5; FeI+,4.3; Fe(SCN)+, 5.5; and Fe(SCN)2, 3.7.
A physical and chemical investigation of the nature and properties of the species formed in the Hg(63P1)–CO system
Authors: London G. , Vikis A. C. , Roy D. J. Le
Published: May 2006

An investigation of the Hg(63P1)–CO system by physical measurements (emission, pressure studies) relevant to the reported Hg*CO species have yielded no additional evidence of its formation.Chemical experiments on the decomposition of ethylene and H2 are in accord with formation of a long lived (> 10−5 s) species. The relative quenching rate constants of the species by C2H4, H2, and CO are 1:0.10–0.18:0.023, respectively.The reliability of the "carbon monoxide effect" as a criterion for distinguishing the nature of the quenching process is discussed in the light of a CO enhancement effect (~ 30%) observed in the Hg(63P1) photosensitized decomposition of hydrogen in the presence of CO and at conditions of incomplete quenching. An alternative to Hg*CO excimer formation is also discussed. This approach is based on the possible formation of Hg(63P0) atoms in quantities in excess of those currently accepted, when Hg–CO mixtures are irradiated with 2537 Å light.
Influence of Lewis acids on the Diels–Alder reaction. III. Rearrangement of dimethyl N-carbomethoxy-7-azabicyclo[2.2.1]2,5-heptadiene-2,3-dicarboxylate adducts to dimethyl N-carbomethoxy-3-aminophthalates
Authors: Bansal R. C. , McCulloch A. W. , McInnes A. G.
Published: May 2006

Aluminum chloride accelerates the Diels–Alder reactions of 2- or 2,5-substituted N-carbomethoxypyrroles with dimethyl acetylenedicarboxylate, and also catalyzes rearrangement of the N-carbomethoxy-7-azanorbornadiene adducts to 6- and 4,6-substituted dimethyl N-carbomethoxy-3-aminophthalates. Aromatization of the corresponding adduct of N-carbomethoxypyrrole only occurs on prolonged treatment with BF3. The procedure promises to be a convenient route for the synthesis of polysubstituted anilines.
Kinetic laws for solid-supported enzymes
Authors: Sundaram P. V. , Tweedale A. , Laidler K. J.
Published: May 2006

Enzymes behave differently when attached to solid supports for four main reasons: (1) their conformations when they are supported may differ from those in free solution, (2) they act upon substrates in a different environment, (3) there will be partitioning of substrate between the support and the free solution, and (4) there will be effects due to diffusion of the substrate in the support. The present paper examines effects (3) and (4) and shows how rates will vary with substrate concentration. If factors (1) and (2) do not enter, rates in the limit of high substrate concentrations will be the same for the supported enzyme as in free solution. At low substrate concentrations, rates will be less for the supported enzyme if the substrate is less soluble in the support than in free solution, and the apparent Michaelis constant, Km(app.), will be greater; conversely, for higher solubility in the support, rates will be greater and Km(app.) smaller. Effect (4) leads to lower rates and higher Km(app.) values, except in the limit of high substrate concentrations. At a sufficiently low thickness of the support, depending upon the activity of the enzyme, the kinetic behavior becomes identical with that in free solution.
Anodic oxidation of organic compounds. V. Electrochemical oxidation of t-butyl hydroperoxide in presence of tetracyclone
Authors: Weinberg N. L.
Published: May 2006

A ring expanded lactone is obtained on electrochemical oxidation of t-BuOOH in presence of tetracyclone. The same product is formed on chemical oxidation of a mixture of t-BuOOH and tetracyclone with cerie ammonium sulfate or on heating the mixture to dryness.
Pyrrole chemistry. X. Friedel–Crafts alkylation of some pyrrole and furan derivatives
Authors: Anderson Hugh J. , Huang C. W.
Published: May 2006

The Friedel–Crafts t-butylation of methyl 2-pyrrolecarboxylate and of 2-acetylpyrrole have been investigated. The results are found to be consistent with the mechanistic pathway suggested in earlier isopropylation papers. Evidence is presented that alkylation of similarly substituted furans may be interpreted in the same way.
Carcinogenicity of lactones. V. The reactions of 4-hydroxypent-2-enoic acid lactone with α-toluenethiol, benzylamine, methylamine, imidazole, and guanidine
Authors: Jones J. Bryan , Barker Jill N.
Published: May 2006

The Michael additions of α-toluenethiol, methylamine, and benzylamine to 4-hydroxypent-2-enoic acid lactone have been confirmed to be facile. The analogous additions of imidazole and glycine amide are much less readily accomplished and no stable Michael addition product could be detected with guanidine as the base. In the pH range 6–9, subsequent lactone ring opening reactions of the Michael addition products were observed only when methylamine (pKa 9.3) and benzylamine (pKa 10.6) were used as nucleophiles.
A structural model for magnesium chloride-containing melts
Authors: Pelton A. D. , Thompson W. T.
Published: May 2006

A structural model for MgCl2-containing melts has been developed, based upon the assumption of MgCl42− complex anions. For the five MgCl2 – alkali chloride and for the MgCl2–AgCl systems, the model gives quantitative, or nearly quantitative, agreement to the experimental enthalpies of mixing in all six systems; to the partial entropies of mixing of alkali chloride in the four systems for which data are available; and to both sides of the phase diagrams in the three systems for which data are available. This is accomplished with the use of only one adjustable parameter for each system, and one other adjustable parameter for all the systems taken together. The same model also quantitatively accounts for the enthalpies of mixing in the five NiCl2 – alkali chloride systems.
Cycloaddition reactions. Addition of dimethyl acetylenedicarboxylate to 1-dimethylaminoindene
Authors: Doyle Terrence W.
Published: May 2006

The cycloaddition of 1-dimethylaminoindene (2) to dimethyl acetylenedicarboxylate to form a fused cyclobutene system 3 is discussed. Compound 3 underwent two modes of ring opening to yield either the indene–maleate system 4 or the benzocycloheptatriene system 5 depending on reaction conditions. The synthesis of a number of multifunctional benzotropones from 5 is discussed.
Stability constants for some 1:1 metal–carboxylate complexes
Authors: Bunting John W. , Thong Kain Men
Published: May 2006

Stability constants have been measured for the formation of 1:1 complexes between eight divalent metal ions and six carboxylate anions. For each anion the stabilities of the complexes follow the order Pb2+ > Cu2+ > Cd2+ > Zn2+ > Ni2+ ~ Co2+ > Ca2+ ~ Mg2+. The stabilities of the complexes with each metal ion are directly related to the basicities of the anions, and little or no bidentate chelation occurs between these metal ions and acetoxyacetic acid or N-acetylglycine.
Transient-phase studies of a trypsin-catalyzed reaction
Authors: Kasserra H. P. , Laidler K. J.
Published: May 2006

The stopped-flow technique has been used to study the pre-steady-state kinetics of the hydrolysis of N-carbobenzoxy-L-alanine-p-nitrophenyl ester catalyzed by trypsin. By working under conditions such that the enzyme concentration is much greater than that of the substrate, it has been possible to measure [Formula: see text] the rate constant for the conversion of the enzyme-substrate complex into the acyl enzyme. The pH dependence of [Formula: see text] reveals a pKb′ value of 6.9 for the conversion of complex into acyl enzyme, in agreement with deductions from steady-state investigations. The pH dependence of [Formula: see text] (equal to k−1 + k2)/k1) has also been determined. The results provide direct evidence for the existence of an enzyme-substrate complex for this reaction.The work has been done in various mixtures of water and isopropyl alcohol. The logarithms of the rate constants [Formula: see text] and [Formula: see text] vary linearly with 1/D, showing a decrease with increasing alcohol concentration; [Formula: see text] increases with alcohol concentration. The solvent results suggest that addition of alcohol affects the hydrophobic bonding in the protein and leads to unfolding of the enzyme.
Electron spin resonance spectra of 15N labelled amino radicals
Authors: Smith D. R. , Seddon W. A.
Published: May 2006

Electron spin resonance (e.s.r.) spectra of radiolytically formed 15NH2 and 15ND2 radicals are presented along with their hyperfine splitting constants and spectroscopic g factors. A comparison with previously observed spectra of 14NH2 and 14ND2 is briefly discussed and their hyperfine parameters revised as a result of our 15N data. Miscellaneous observations on the effect of additives (water, methyliodide, tetranitromethane) are discussed.