bluuebunny/crossref_metadata_2025 huggingface dataset:
Ion Pair Formation in NaNO3/D2O Solutions: Raman and Infrared Spectra, Partial Molal Volumes, Conductance, and Viscosity
Authors: Riddell J. D. , Lockwood D. J. , Irish D. E.
Published: May 2006

Laser Raman and infrared vibrational spectra of solutions of NaNO3 in deuterium oxide reveal the presence of both [Formula: see text] ion pairs and solvated nitrate ions. The degree of association has been measured. The concentration quotients are remarkably independent of concentration and almost equal to the thermodynamic association constant, 0.060 ± 0.006 kg mol−1 at 25.0 °C. The latter quantity was obtained by an extrapolation procedure, taking account of the activity coefficients. Values are reported for the activity coefficient of the ion pair. Interpretation is also considered in terms of a place-exchange equilibrium involving the solvent. Vibrational assignments are made to the two forms of nitrate ion present. Density, partial molal volume, conductance, and viscosity data are also presented and discussed in terms of the reported constitution.
Pyrolysis of 3-Chloro-3-aryldiazirines, Kinetics and Mechanism
Authors: Liu Michael T. H. , Toriyama K.
Published: May 2006

The thermal decomposition of 3-chloro-3-aryldiazirines in various solvents has been investigated over the temperature range 60–100 °C. The intermediate carbenes have been isolated as norcaranes by the use of cyclohexene. Substituent effects on rates of reaction are small and a Hammett correlation was unsuccessful with either σ or σ+ constants. Possible mechanisms for the decompositions are discussed.
The Oxidation of Tetrahydrofuran by Ruthenium Tetroxide
Authors: Lee Donald G. , Engh Matthijs Van Den
Published: May 2006

The kinetics of the oxidation of tetrahydrofuran by ruthenium tetroxide in aqueous perchloric acid solutions have been investigated. The rate of reaction is found to be directly dependent on the concentrations of oxidant and reductant, but inversely dependent on the acidity of the medium. A mechanism involving hydride abstraction in the rate determining step was found to be consistent with the evidence obtained from isotopic labeling and an analysis of the activation parameters (ΔH≠ = 14.0 kcal/mol, ΔS≠ = −18.4 e.u.) of the reaction. This conclusion is further substantiated by noting the similarity between the reactions of ruthenium tetroxide with alcohols and ethers.
A Comparative Study of Bu4NBr, NaBPh4, Ph4PCl, and Ph4AsCl in Water and Methanol at 25 °C: Partial Molal Volumes, Heat Capacities, and Viscosities
Authors: Jolicoeur C. , Philip P. R. , Perron G. , Leduc P. A. , Desnoyers J. E.
Published: May 2006

The apparent molal volumes [Formula: see text] and heat capacities [Formula: see text] of Bu4NBr, NaBPh4, Ph4PCl, and Ph4AsCl have been measured in water and methanol at 25 °C in the concentration range 0.01–0.2 M. The viscosity of aqueous NaBPh4 and Ph4AsCl have also been measured at 25 °C and in the same concentration range. Individual ionic values have been estimated for most of these properties. A comparison of these values for the quaternary ions BU4N+, [Formula: see text], Ph4P+, Ph4As+ illustrates sizable differences in the solute–solvent interactions of alkyl and aryl substituted ions. Some specificity is also suggested in the solvation of the tetraphenyl ions, as shown by a comparison of the properties which should reflect directly the size of the ions [Formula: see text]and also in (H2O → CH3OH) transfer functions.
Rearrangement Studies with 14C. XXXVII. The Treatment of 1-14C-1-Chlorobutane with Aluminum Chloride
Authors: Lee C. C. , Ponce I. Y. Zea
Published: May 2006

After treatment of 1-14C-1-chlorobutane with anhydrous AlCl3 at 20° for 20, 60, or 120 min, the isomeric chlorobutanes recovered were mainly n-butyl and sec-butyl, with small amounts of t-butyl and iso-butyl chlorides. Degradations showed only 0.2–0.4% rearrangement of the 14C-label from C-1 to -2 in the recovered 14C-1-chlorobutane, while extensive scramblings over all four carbon positions were noted for the recovered 14C-2-chlorobutane. Successive 1,2-hydride shifts interconverting the 2-butyl cations or ion-pairs were found to play a major role in accounting for the scrambling data. It was concluded that processes involving protonated methylcyclopropanes could not be the main pathway for the rearrangement of the label into C-2 and -3 of the 14C-2-chlorobutane. 1,2-Ethyl followed by 1,2-hydrogen shifts giving rise to encumbered 2-butyl cations with different structural features appeared to be required to explain the 14C-contents in the C-2 and -3 positions.
The Crystal and Molecular Structure of Trinitrato-2,2′-bipyridylmanganese(III): A Complex with Three Distinctly Different Nitrate Ligands
Authors: Einstein F. W. B. , Johnson D. W. , Sutton D.
Published: May 2006

The 2,2′-bipyridyl complex of manganese trinitrate, Mn(NO3)3•bipy, forms monoclinic crystals, space group P21/c with four molecules in a unit cell with dimensions of a = 7.311(3), b = 18.022(7), c = 11.704(4) Å, and β = 108.73(3)°. The manganese atom is seven co-ordinate, with approximate pentagonal bipyramidal geometry. The equatorial ligand atoms consist of one nitrogen of the bipyridyl group and four oxygens from two bidentate nitrate groups; the remaining bipyridyl nitrogen and the coordinated oxygen of the unidentate nitrate group are at the apices. This is the first nitrato-complex to be shown by crystallography to possess three distinctly different coordinated nitrate groups. One nitrate group is unidentate with Mn—O = 1.896(8) Å, one is symmetrical bidentate with Mn—O = 2.236(8) and 2.201(8) Å and one asymmetric bidentate with Mn—O = 2.112(8) and 2.400(9) Å.
Kinetics of Displacement of Ni(II) by Cu(II) in Bis(dithiocarbamato)nickel(II)
Authors: Scharfe R. R. , Sastri V. S. , Chakrabarti C. L.
Published: May 2006

Rates of displacement of Ni(II) in bis(dithiocarbamato)Ni(II) by Cu(II) with a variety of substituted dithiocarbamic acids in different solvents have been determined and a mechanism of the reaction and potential application of the displacement reaction to spectrophotometric titration of Cu(II) for its quantitative determination are suggested.
Circular Dichroism of R-1,2-Propanediamine Complexes of Copper(II)
Authors: Haines Roland A. , Crews E. Wendy
Published: May 2006

The optical activity associated with solutions containing copper(II) ions and R-1,2-propanediamine (R-pn) has been examined in detail. Circular dichroism data previously reported for [Cu(R-pn)2]2+ have been found to be in error and new data are reported for this ion, as well as [Cu(R-pn)]2+.
Reaction of N-Acetyl-2,3-diphenylindole with Nitric Acid
Authors: Dave Vinod , Warnhoff E. W.
Published: May 2006

Based on spectroscopic and chemical evidence the 3-hydroxy-6-nitro-2,3-diphenylindolenine structure 8 is assigned to the previously reported N-acetyl-2,3-diphenylindole–nitric acid reaction product. The product from the acid-catalyzed rearrangement of 8 is assigned the oxindole structure 12.
19F N.M.R. Study of the Difluorochlorine(III) Cation,
Authors: Brownstein Morley , Shamir Jacob
Published: May 2006

The 19F n.m.r. spectrum of [Formula: see text] has been observed for the first time. Solvolysis of the [Formula: see text] cation in neutral anhydrous hydrogen fluoride to give ClF3 is extremely slight.
The Thermal Decomposition of N-Arylcarbamates of t-Alcohols. 2. Effects of Solvent, Temperature, and Substituents
Authors: Ashcroft S. J. , Thorne Melanie P.
Published: May 2006

The influence of solvent, ring substituents, and tertiary carbon atom substituents on the decomposition at 423–473 K of some N-arylcarbamates of tertiary alcohols (p-XC6H4NHCO2C(CH3)2R, where X = CH3, H, Cl, NO2, R=C≡CH, C2H5, CH=CH2) has been investigated. In dodecane, diphenyl ether, acetophenone, nitrobenzene, and decanol, the reactions were first order yielding chiefly carbon dioxide, amine, and olefin. t-Pentyl carbamates yielded the olefins 2-methyl-1-butene and 2-methyl-2-butene in a 3:1 mixture. Solvent effects are reflected in variations in enthalpies and entropies of activation, but effects on the actual values of the specific rate constants are small. Substituent effects are also small, with changes in R from C≡CH to CH=CH2 producing only a tenfold rate increase. Variations in X yield Hammett σρ plots with slopes of about 0.50. These results are consistent with the charge separated cyclic transition state proposed before (1). In ethylene glycol, increased reaction rates and 1:1 yields of the olefins from the t-pentyl carbamates indicate a mechanism with greater carbonium ion character.
Binary Dioxygen Complexes of Nickel; Infrared Spectroscopic Evidence for Ni(O2) and (O2)Ni(O2) in Low Temperature Matrices
Authors: Huber H. , Ozin G. A.
Published: May 2006

The cocondensation reaction of nickel atoms with oxygen or dilute oxygen–argon matrices at 4.2–10 °K gives rise to the first examples of binary transition metal dioxygen complexes. Variable concentration and diffusion controlled warm up studies and 16O2, 16O18O, 18O2 isotope substitution studies establish the stoichiometries of the dioxygen complexes of nickel to be Ni(O2) and (O2)Ni(O2). Both complexes have the dioxygen molecule(s) coordinated to the nickel atom in a "sideways" fashion.
The Trifluoroacetic Acid Solvent System. Part IV. Triple Ions
Authors: Harriss M. G. , Milne J. B.
Published: May 2006

Electrolytes studied in 100% trifluoroacetic acid exhibit a minimum in equivalent conductivity with increasing solute concentration. This behavior is accounted for by the formation of triple-ions at higher concentrations. Triple-ion dissociation constants, k, have been evaluated and, in general, they show the opposite trend with changing ion size to that of the ion-pair dissociation constants; that is the triple-ions of smaller ions are more dissociated. The experimentally observed trend is accounted for by using a partial ionic charge instead of unit charge for the ion-pair charges in the theoretical Fuoss expression for k.The excellent extrapolation of the triple-ion data to give a value of Λ0Kd for the ion-pair, which agrees well with that determined from a Fuoss plot, permits an estimate of Λ0 for LiO2CCF3 from the triple-ion data.
Some Mixtures of Carbon Tetrachloride with Several n-Alkanes: Enthalpies and Energies of Mixing
Authors: Berryman James M. , Heric E. L.
Published: May 2006

Molar enthalpies of mixing for the five n-alkanes from pentane through nonane with carbon tetrachloride at 298.15 K have been measured. The maximum values are, with increasing chain length, 295, 315, 339, 373, and 417 J. Energies calculated from the enthalpies are compared with the lattice theory of mixtures. The comparison is also extended through hexadecane, using previously reported results.
A New Synthesis of 5-Phenyl-2,3-dihydro- and 2,3,4,5-Tetrahydro-1H-2-benzazepin-1-ones
Authors: Ackerman K. , Horning D. E. , Muchowski J. M.
Published: May 2006

It was shown that 3-phenyl-3-(2-aminoethyl)phthalide (6, R = H) and its N-methyl analog (6, R = CH3) existed in the amino lactone form in solution at room temperature. In the absence of solvents, however, these compounds underwent a spontaneous transformation into the 5-phenyl-2,3,4,5-tetrahydro-1H-2-benzazepin-1-ones (8, R = H, CH3) which suffered dehydration in sulfuric acid with the formation of 5-phenyl-2,3-dihydro-1H-2-benzazepin-1-ones (9, R = H, CH3).This benzazepine synthesis can be considered to be analogous to the known (12–15) conversion of 1-aminomethylphthalides (11) to 4-hydroxy-3,4-dihydroisocarbostyrils (13).
P.M.R. Spectroscopy of Trimethylsilyl Derivatives of Hydroxy Acids
Authors: Dutton Guy Gordon Studdy , Funnell Norman , Gibney Kelly Blair
Published: May 2006

P.m.r. spectroscopy at 60 MHz of trimethylsilyl ethers and esters, prepared from hydroxy acids, gives well resolved sharp singlets in the range τ 9.8–9.9, These signals may be used to determine the ratio of hydroxyl to carboxyl groups in a molecule. Measurements may be made directly on fractions isolated by gas–liquid chromatography. The influence of the solvent on the resolution is demonstrated.
Thiohydantoins. XII. Secondary Deuterium Isotope Effects in the Acid- and Base-catalyzed Hydrolysis of 1-Acetyl-5,5-dimethyl-2-thiohydantoin
Authors: Congdon Wayne I. , Edward John T.
Published: May 2006

The rates of hydrolysis of 1-acetyl-5,5-dimethyl-2-thiohydantoin and of 1-acetyl-d3-5,5-dimethyl-2-thio-hydantoin in acid and base over the temperature range 11–58 °C have been measured. For the A-1 hydrolysis in 96.3% sulfuric acid, kH/kD decreased from 1.31 at 10.8° to 1.05 at 58.1°; these results accord with the proposed mechanism. For A-2 hydrolysis in 39.6% sulfuric acid and for base-catalyzed hydrolysis in dilute sodium hydroxide, kH/kD υs. temperature passed through a minimum at about 40 and 25° respectively. Some possible reasons for the temperature effect are discussed.
Correlation of π,π* Triplet Energy of some Cyclic α,β-Unsaturated Ketones with Electroreduction Potentials
Authors: Loutfy Rafik O. , Loutfy Raouf O.
Published: May 2006

The half-wave reduction potentials, E1/2's, of some cyclic enones have been determined in acetonitrile. A linear free-energy relationship was obtained between E1/2 and the lowest π,π* triplet state of the enones studied. This correlation enabled an estimate to be made of the triplet energy of the cyclohexenone, which was found to be ~70 kcal/mol.
Isopropyl Tri-O-acetyl-α-D-hexopyranosulosides. The Configurations of the Parent Oximes
Authors: Lemieux R. U. , Earl R. A. , James K. , Nagabhushan T. L.
Published: May 2006

A variety of methods are described for the deoximation of isopropyl tri-O-acetyl-2-oximino-α-D-arabino-hexopyranoside (1) to isopropyl tri-O-acetyl-α-D-arabino-hexopyranosuloside (3). Using acetaldehyde in acetonitrile and hydrochloric acid, both 3 and its lyxo-isomer (4), from the corresponding oxime (2), were obtained in crystalline form. Comparisons of the chemical shifts of the anomeric hydrogens of the ulosides with those of the corresponding oximes require the oximes to possess the C-1/OH syn- or Z-configuration.
Preparation and Stereochemistry of N-Methyl-N-phenacylpiperidinium Salts
Authors: Smith Robert V. , Benz Frederick W. , Long John P.
Published: May 2006

The N-methyl-N-phenacylquaternary salts of 2-, 3-, and 4-methylpiperidines have been prepared and characterized. N.m.r. spectroscopy was employed in analyzing the proportion of diastereomers formed following reciprocal alkylations with methyl iodide and phenacyl halides. Preferential axial attack was observed with N-methylation while N-phenacylation primarily proceeded by equatorial attack.
Crystal Structure of LiVO3
Authors: Shannon Robert D. , Calvo Crispin
Published: May 2006

Lithium metavanadate is monoclinic with a = 10.158(2), b = 8.4175(9), c = 5.8853(9) Å, β = 110.48(2)° and probable space group C2/c. The structure, refined by least-squares to a ωR = 0.033 using 851 reflections, is isotypic with LiAlSi2O6 (spodumene) and LiFeSi2O6. Bands of Li—O edge-shared octahedra run parallel to c and are linked by chains of VO4 tetrahedra which also run parallel to c. The mean Li(1)—O and Li(2)—O distances are significantly different, 2.153(3) and 2.284(3) Å, and are related to the degree of distortion of individual distances from the mean. The V—O distances of 1.821, 1.795, 1.662, and 1.628 Å with a mean value of 1.725 Å are consistent with bond strength sums around the oxygen atoms and empirical bond length – bond strength curves.
The Photolysis of Propane at 123.6 nm
Authors: Vorachek James H. , Koob Robert D.
Published: May 2006

Propane has been photolyzed at 123.6 nm, in the presence and absence of O2, at pressures from 2–380 Torr. All products except ethane exhibit a pressure dependence which is attributed to secondary dissociation of the primary fragments, H2, CH4, C2H4, and C3H6. It is assumed that the range of energies carried by these fragments is broad enough that some will not dissociate even at low pressures while others of the same species cannot be stabilized even at high pressures. An internally consistent analysis rationalizes the entire observed product spectrum, with some uncertainty arising from an ambiguity in the source of acetylene. The following primary quantum yields, prior to secondary dissociation, are estimated:[Formula: see text]
Comparison of the Complexation Constants of Some Cyclic Imides and Thioimides with Proton Acceptors
Authors: Gall Luc Le , Narvor Anne Le , Lauransan Jacques , Saumagne Pierre
Published: May 2006

The complexation constants of some imides and thioimides in hydrogen-bonded complexes with proton acceptor molecules were determined by i.r. spectroscopy. The results permit a comparison between the proton donating abilities of these compounds. It is possible to classify them against other well-known proton donors.
4-Methyl-3,3-pentamethylene-1,2-dioxetane. Lack of its Formation in Ozonation of Ethylidenecyclohexane in Pinacolone
Authors: Kopecky Karl R. , Lockwood Peter A. , Filby John E. , Reid Ronald W.
Published: May 2006

The title compound has been prepared and characterized. Contrary to a previous report it is not formed on ozonation of ethylidenecyclohexane (1) in pinacolone. The percent yields of products formed on ozonation of 1 in Skelly B, pinacolone, and dimethyl ether are, respectively, acetaldehyde, 25, 47, 59; normal ozonide ~75, ~0, <15; and dimeric cyclohexanone peroxide 11, 17, 35.
Microwave Spectrum of Cyclohexene Sulfide
Authors: Kewley R.
Published: May 2006

The microwave spectrum of cyclohexene sulfide (7-thiabicycIo[4,1,0]heptane) has been investigated in the 26.5–40 GHz region. R-branch lines due to both a- and c-type transitions have been assigned for the ground vibrational state and for the first excited states of the ring bending and ring twisting modes. From relative intensity measurements the frequencies of these two modes are estimated as: vbend = 115 ± 20 cm−1 and vtwist = 200 ± 60 cm−1. The rotational constants for the ground vibrational state are (in MHz): A = 3512.086 ± 0.010, B = 2057.969 ± 0.003, and C = 1623.023 ± 0.003. These values are consistent with a twisted half chair structure for the heavy atom skeleton of cyclohexene sulfide, similar to that of cyclohexene oxide.
The Crystal Structure of cis-Dichloro(2,2′-oxydi-3-butene)platinum(II), PtCl2((CH2=CH—CH(CH3))2O)
Authors: Hubert J. , Beauchamp A. L. , Theophanides T.
Published: May 2006

The reaction of K2PtCl4 with CH3—CH=CH—CH2—OH yields the complex cis-[PtCl2((CH2=CH—CH(CH3))2O)]. The crystals are triclinic, space group [Formula: see text], a = 9.420(2) Å, b = 8.359(4) Å, c = 7.837(4) Å, α = 91.10(4)°, β = 62.13(4)°, γ = 80.80(5)°, and Z = 2. The structure, solved by standard methods, has been refined anisotropically by full matrix least-squares methods to a R factor of 0.052 by use of 2441 independent observed reflections. The complex is a monomer, where both double bonds of the diolefin ether are coordinated to the platinum atom as in Zeise's salt. The usual square planar coordination of platinum(II) is completed by two chlorine atoms. The (=CH2) groups of both double bonds are found on the same side of the coordination plane. Various possible conformations of the coordinated ligand in the complex are discussed.
Halogen Ring Monosubstituted Benzoic Acid Hydrazides as Ligands. II. Ultraviolet Spectra and pK Determination
Authors: Manoussakis George , Haristos Demetrius , Youri Catherine
Published: May 2006

The u.v. spectra of 12 halogen-substituted benzoic acid hydrazides are reported. A very intense band in the region 225–260 mμ and a second one of low intensity at 270–290 mμ are assigned to π → π* and n → π* transitions, respectively.The pK1 and pK2 of the mentioned hydrazides, corresponding to the Brönsted acids [Formula: see text] and XC6H4C(OH)=NNH2 respectively, were obtained spectrophotometrically (X = F, Cl, Br, or I in o-, m-, and p-position). The influence of the nature and the position of the halogen atom on the pK values is discussed.
Experimental and Theoretical Estimates of Sigma and Pi Electron Contributions to Long-range Spin–Spin Coupling Constants in Coumarin and its Methyl Derivatives
Authors: Rowbotham J. B. , Schaefer T.
Published: May 2006

A full analysis of the p.m.r. spectra of coumarin and five of its methyl derivatives allows the assignment of σ and π electron components to the inter-ring proton–proton spin–spin coupling constants. Magnitudes of up to 0.3 Hz are observed over a coupling path of eight bonds. The σ and π components can be combined on the basis of the appropriate valence bond structures to predict closely the observed parameters in naphthalene, suggesting only weak participation of the ether oxygen atom in the π electron system of coumarin. Calculations of the inter-ring coupling constants at the INDO and CNDO/2 levels of molecular orbital theory are helpful in the interpretation of the observed data, the agreement with experiment being quantitative in many instances. Comparison of the observed coupling constants in coumarin and styrene with the INDO results for an assumed planar form of the latter suggests that styrene exists in a nonplanar conformation.
A Synthesis of 2-Amino-2,6-dideoxy-D-(and L-)galaetose (Fucosamine) and 2-Amino-2,6-dideoxy-D-(and L-)talose (Pneumosamine)
Authors: Perry Malcolm B. , Daoust Virginia
Published: May 2006

5-Deoxy-D-lyxose underwent base-catalyzed addition with nitromethane to give a mixture of 1,6-dideoxy-1-nitro-D-galactitol and 1,6-dideoxy-1-nitro-D-talitol (ca. 2:1). Acetylation of the crystalline 1,6-dideoxy-1-nitro-D-galactitol gave 2,3,4,5-tetra-O-acetyl-1,6-dideoxy-1-nitro-D-galactitol which on treatment with methanolic ammonia afforded 2-acetamido-1,2,6-trideoxy-1-nitro-D-talitol and 2-acetamido-1,2,6-trideoxy-1-nitro-D-galactitol (ca. 3:1) which under the modified Nef reaction conditions gave 2-acetamido-2,6-dideoxy-D-talose and 2-acetamido-2,6-dideoxy-D-galactose respectively. The glycoses were converted to 2-amino-2,6-dideoxy-D-talose hydrochloride and 2-amino-2,6-dideoxy-D-galactose hydrochloride on hydrolysis with hydrochloric acid.A similar reaction sequence applied to 5-deoxy-L-lyxose afforded the L-enantiomorphic intermediates, and gave 2-amino-2,6-dideoxy-L-talose hydrochloride and 2-amino-2,6-dideoxy-L-galactose hydrochloride as final products.
Comparisons between Orientation Polarizations and Atom Polarizations among Organomercurials
Authors: Wright George F
Published: May 2006

Although a correlation between orientation and atom polarizations among simple aryl and alkyl mercurials is limited, a definite but inverse correlation is found for 2-oxyorganomercuric salts.
Folded Conformations. IV. Intramolecular Shielding and Intramolecular Charge-Transfer Interaction in Benzyl Phenyl Sulfones and Sulfoxides
Authors: Est-Stammer (Mrs.) Renée van , Engberts Jan B. F. N.
Published: May 2006

Proton magnetic resonance spectra of the title compounds (A-SO2CHR-D) were measured and compared with the spectra of appropriate reference systems containing an alkyl substituent instead of one of the aromatic rings. The observed upfield shifts of the aromatic proton resonances in the title compounds suggest that there is a significant population of folded conformations, which possess a gauche orientation of the aromatic rings. This conclusion is supported by the observation of an intramolecular charge-transfer band in the u.v. spectra of the compounds containing an A ring of high electron affinity and a D ring of low ionization potential. Stabilization of the folded forms may be obtained through minimizing the n–π repulsive forces between the sulfonyl oxygen lone pairs and the π-electron system of the D ring.
Crystal Structure of β-D, 1 → 4 Xylobiose Hexaacetate
Authors: Leung F. , Marchessault R. H.
Published: May 2006

Three dimensional crystal structure analysis has been carried out on β-D, 1 → 4 xylobiose hexaacetate (1)[Formula: see text]The crystal data are: orthorhombic, P212121, a = 10.938(2), b = 8.377(4), c = 29.976(7) Å. It was found that the bond lengths and angles of the Cl chairs are similar to other carbohydrate structures, the conformational angles (Φ,Ψ) = (20.4°, −15.2°) and the orientations of the acetate groups are in good agreement with those predicted by stereochemical calculations using Flory functions. The structural resemblance between this molecule and the polymer, xylan diacetate, is discussed.
Fungal Steroids. A Stereoselective Synthesis of Isoantheridiol
Authors: Popplestone C. R. , Unrau A. M.
Published: May 2006

The synthesis and characteristics of the 23-hydroxy-δ-lactone isomer of antheridiol and (22S,23R) 3β-hydroxy-24-carbethoxymethylene-cholest-5-en-22,23-epoxide are described. The synthesis of the latter compound follows from the highly stereoselective epoxidation of 3β-acetoxy-cholesta-5,22-diene-24-one followed by a Wittig reaction to give (22S,23R) 3β-acetoxy-24-carbethoxymethylene-cholest-5-en-22,23-epoxide which upon treatment with perchloric acid gave exclusively the δ-lactone. Hematoporphyrin-sensitized photooxygenation followed by cupric acetate oxidation gave the required α,β-unsaturated ketonic system in ring B. The 22R,23S stereochemical assignment of the final product is based on circular dichroism spectra.
A Low-temperature Infrared Study of Self-association in Thiolic Acids
Authors: Alencastro R. Bicca de , Sandorfy C.
Published: May 2006

The i.r. spectra of thioloacetic and thiolobenzoic acids were measured in both the fundamental and first overtone regions of the S—H stretching vibration, in a mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. [Formula: see text] type bonds are formed at low temperatures or at high concentrations of solute. Two different species can be detected. The first is probably an open dimer and the second a cyclic dimer. The S—H anharmonicity constants are of the order of 50–60 cm−1, for both free and associated species, and have about the same value as in aliphatic or aromatic mercaptans. Carbonyl groups have lower anharmonicities. Their value is about 10 cm−1, for both free and associated species.
Mass Spectrometry of Some Substituted 2-Benzylidenecyclohexanones and 2,6-bis-Benzylidenecyclohexanones
Authors: Smith P. J. , Dimmock J. R. , Turner W. A.
Published: May 2006

The mass spectra of a series of some substituted 2-benzylidenecyclohexanones and a series of substituted 2,6-bis-benzylidenecyclohexanones have been determined at 70 eV. The major fragmentation pathways include an intramolecular aromatic substitution reaction leading to the loss of an ortho-substituent with the formation of a stable benzopyrylium ion, loss of carbon monoxide and ethylene from the parent ion and also further ions derived from subsequent cleavages of the cyclohexanone ring. The structural and electronic factors involved in the aromatic substitution reaction were examined by comparing the M – H/M and M – Cl/M ratios determined from the spectra of the various substrates.
The Reaction of O3 with CCl2CH2
Authors: Hull Leslie A. , Hisatsune I. C. , Heicklen Julian
Published: May 2006

The gas-phase reaction of O3 with CCl2CH2 at 25 °C was studied by monitoring O3 consumption by ultraviolet absorption and product formation and olefin consumption by infrared absorption. In the absence or presence of excess N2, and for initial olefin-to-O3 ratios, [CCl2CH2]0/[O3]0, in excess of 20 ([O3]0 ~ 1.0 Torr), the rate law is[Formula: see text]with k = 2.4 × 106 M−2 s−1. At lower olefin-to-O3 ratios, the rate is initially more rapid than predicted by the above equation, but follows the equation after the reaction has proceeded for some time. In the presence of excess O2, the rate is markedly reduced, and the rate law becomes[Formula: see text]with k′ = 2.2 M−1 s−1.The products of the reaction are CCl2O, HCOOH, CH2ClCCl(O), CO, O2, HCl, and presumably H2O. In the absence of O2, the CCl2CH2-to-O3 consumption ratio approaches 2, but the CCl2O produced per O3 consumed is between 0.25 and 0.4. With excess O2, the latter ratio becomes unity, but the CCl2CH2-to-O3 consumed approaches 5.The results are interpreted in terms of a chain mechanism with CCl2O2 as the chain carrier. The mechanism developed explains the main features of the reaction.
The Molecular Conformation of 1e,2a,6e-Trimethyl-4e-phenyl-4a-acetoxypiperidine Hydrobomide in the Crystalline State
Authors: Hayakawa K. , James M. N. G.
Published: May 2006

The title compound represents one analog of the synthetic 4-phenylpiperidine narcotic analgesics. The crystal structure was determined by the heavy-atom method from data collected on an automated diffractometer. The crystals are monoclinic, space group P21/c, with unit cell dimensions a = 11.833 Å, b = 11.551 Å, c = 14.659 Å and β = 121° 9′. The final residual, R, was 0.056. The stereochemistry of the substituents on the piperidine ring as deduced by this structural determination (1e,2a,6e-trimethyl-4e-phenyl-4a-acetoxypiperidine) confirms the p.m.r. results on the alcohol precursor as trans 2-Me/6-Me and trans 2-Me/4-Ph. There is a normal length N—H … Br hydrogen bond of 3.234 Å; most intramolecular bond lengths and angles are within the expected ranges but some distortion of the ideal chair conformation of the piperidine ring occurs.
Temperature Dependence of Activation Volumes of Solvolysis Reactions in Light and Heavy Water
Authors: Davis Claude S. , Hyne J. B.
Published: May 2006

The pressure dependence of the solvolysis rates for benzyl chloride, isopropyl bromide, and methanesulfonyl chloride in H2O and D2O have been measured. The temperature dependence of the activation volumes appears to be indicative of the mechanism of solvolyses and the differences in the temperature dependence of the activation volumes for the two solvents are consistent with D2O being the more structured. The more extensive data in the case of methanesulfonyl chloride deuterolysis indicates extremum behavior in ΔV* as a function of temperature in the 5–25 °C range.
The Photochemistry of a Dihydropyridazine
Authors: Mayo P. De , Usselman M. C.
Published: May 2006

Irradiation of a 5,6-dihydropyridazine in either the n → π* or π → π* absorption bands results in ring-opening to the two isomeric diazatrienes expected of a concerted, electrocyclic process. Population of the triplet state of the dihydropyridazine by sensitization also results in ring-opening, but much less efficiently. The quantum yields of the two processes were found to be 0.40 ± 0.04 and 0.07 ± 0.01, respectively. The primary photoproducts, cis,cis- and cis,trans-4,5-diazatriene, isomerize thermally at temperatures greater than 20° to the trans,cis and trans,trans isomers.
Crystal and Molecular Structure of tetrakis(4-Methylpyridine)nickel(II)perchlorate, [Ni(II)(C6H7N)4][ClO4]2
Authors: Bose N. , Lynton H.
Published: May 2006

Crystals of tetrakis(4-methylpyridine)nickel(II)perchlorate, Ni(C6H7N)4(ClO4)2, are monoclinic, space group C2/c, with a = 18.38(1), b = 10.71(1), c = 15.58(1) Ǻ, β = 109.83(5)°, and four molecules in the unit cell. The final atomic parameters were obtained from a block-diagonal least squares refinement using anisotropic thermal parameters. The hydrogen atom positions were established but the parameters were not refined. The final agreement residual for 1199 observed reflections is R = 0.049. The structure consists of discrete Ni(C6H7N)42+ and ClO4− groups. The perchlorate ion is disordered. The 4-methyl-pyridine rings are in a square planar arrangement about the nickel atom.
The Molecular Structures of the Polysulfuryl Fluorides by Vapor Phase Electron Diffraction: S2O5F2 and S3O8F2
Authors: Hencher J. Lawrence , Bauer S. H.
Published: May 2006

The molecular structures of the polysulfuryl fluorides, S2O5F2 and S3O8F2, were determined by vapor phase electron diffraction. In each case it was assumed that a single rotomer was more stable than all others, by at least 2.5 kcal mol−1. The possibility that the sample consisted of a mixture of conformations of comparable stabilities was not explored.The thermally averaged rg parameters for S2O5F2 are as follows: S=O = 1.398 ±.002 Å; S—F = 1.525 ± 0.005 Å; S—O = 1.611 ± 0.005 Å; ∠SOS = 123.6 ± 0.5°; ∠OS=O = 106.1 ± 0.9°; ∠FS=O = 106.6 ± 0.6°; ∠O=S=O = 126.8 ± 1.2°; ∠OSF = 102.4 ± 1.8°; τFS/OS′ = 53.8 ± 2.7°; τF′S′/OS = 73.7 ± 2.4°. The rg parameters for S3O8F2 are: S=O = 1.402 ± 0.003 Å; S—F = 1.525 ± 0.012 Å; S—O = 1.613 ± 0.006 Å; ∠OSO = 97.8 ± 1.0°; ∠SOS = 123.6 ± 1.2°; ∠OS=O = 106.5 ± 0.8°; ∠FS=O = 105.5 ± 1.2°; ∠O=S=O (bridge) = 128.8 ± 1.4°; ∠O=S=O = 128.5 ± 1.4°; ∠OSF = 101.3 ± 1.5°; τSO/SO = 295.3 ± 0.9°; τFS/OS = 319.4 ± 2.2°. The standard errors listed are three times the calculated values and are believed to encompass the non-random errors in the analysis.
The Rate Coefficient for CH3 + H2 → CH4 + H Measured in Reflected Shock Waves; A Non-Arrhenius Reaction
Authors: Clark Thomas C. , Dove John E.
Published: May 2006

Dynamic sampling of reacting gas mixtures behind reflected shock waves has been used to determine the concentration vs. time profiles of the products of the recombination chain reactions of methyl radicals in the presence of molecular H2. The radicals were produced by the rapid pyrolysis of azomethane. By analysis of profiles from experiments in the temperature range 1272–1370°K we have deduced a value of the rate coefficient of reaction 5: CH3 + H2 → CH4 + H.[Formula: see text]It is shown that although this value of k5 does not lie on the Arrhenius line drawn through lower temperature data, it does lie close to the upward curved Arrhenius plot of values of k5 calculated by the B.E.B.O. transition state method. Taking a mean activation energy calculated by the B.E.B.O. method, our results suggest the following description for k5 over the temperature range 1200 to 2000°K:[Formula: see text]
Photochemistry of 2,4-Cyclooctadienone I. In Benzene and Toluene
Authors: Lange Gordon L. , Neidert Eli
Published: May 2006

Irradiation of 2,4-cyclooctadienone (1) in benzene or toluene is shown to give in >80% yield two head-to-head dimers. The ring fusions are shown to occur at the α,β-positions of the dienone with trans-cis and trans-anti-trans stereochemistry. Both dimers may be epimerized to the same product with cis-anti-cis ring fusions. Evidence is presented to show that the singlet state is responsible for the cis-trans isomerization of 1 to the highly reactive intermediate trans, cis-2,4-cyclooctadienone. This intermediate can dimerize in a thermal 2 + 2 cycloaddition or can be generated at −78° and then trapped by 1,3-dienes in a Diels–Alder reaction. A mechanism for the dimerization reaction is discussed.
The Electrical Polarization of 1,4-Dicyanobenzene
Authors: Huber Helmut , Wright George F
Published: May 2006

The anomalous total electric polarization of 1,4-dicyanobenzene has been shown not to be due to high atom polarization by dielectric constant measurement of the solid substance and by its spectral absorption in the far i.r. However the evaluation of atom polarization from the spectral absorption is questioned because these absorptions have a large temperature coefficient in the 50–150 cm−1 region. The apparent dipole moment of 1,4-dicyanobenzene in solution has been measured and found to be temperature-dependent.
Temperature and Pressure Dependence of 35Cl Nuclear Quadrupole Resonance in BiCl3
Authors: Gillies G. C. , Brown R. J. C.
Published: May 2006

The temperature and pressure dependences of the two 35Cl nuclear quadrupole resonances in BiCl3 have been measured. At constant pressure, the temperature coefficients are markedly different and this difference is shown to be due to volume effects associated with different intermolecular bonding.
Tricyclic Hydrocarbons. II. Carbon-13 Nuclear Magnetic Resonance Spectroscopy as a Method for Unambiguous Structure Determination
Authors: Buchanan Gerald Wallace , Wightman Robert Harlan
Published: May 2006

Carbon-13 n.m.r. spectroscopy is demonstrated to be unique as an unambiguous and general method for determining structure in a series of isomeric tricyclic benzenoid hydrocarbons. Observed carbon shieldings for the tricyclic materials are discussed and compared with those for related bicyclic and monocyclic compounds.
Dihedral Angular Dependence of H—N—C—H Coupling Constants. Protonated Amines in Trifluoroacetic Acid
Authors: Fraser Robert R. , Renaud Roger N. , Saunders John K. , Wigfield Yuk Y.
Published: May 2006

Measurements of vicinal H—N—C—H coupling constants in the conjugate acids of two tertiary amines having known rigid conformations provide support for the validity of the Karplus relation for this type of coupling constant. Seven vicinal coupling constants agree to within 0.5 Hz with those calculated from the expression [Formula: see text].
Total Synthesis of Spirobenzylisoquinoline Alkaloids. Part III (±)-Ochrobirine
Authors: McLean Stewart , Whelan John
Published: May 2006

The route to spirobenzylisoquinoline alkaloids through a Pictet–Spengler cyclization of a suitable 1,2-indanedione has been modified, by the introduction of a 3-bromo substituent into the indanedione, with a view to providing a general synthesis of spirobenzylisoquinoline alkaloids bearing two oxygen functions on ring C. A highly stereoselective synthesis of (±)-ochrobirine has been achieved.
Photoreactions of Nitroso Compounds in Solution. XXIV. Photooxidation and Photodecomposition of C-Nitroso Compounds
Authors: Chow Y. L. , Tam J. N. S. , Pillay K. S.
Published: May 2006

Irradiation of the anti-dimers of C-nitroso compounds under nitrogen caused dissociation to the corresponding C-nitroso monomer which underwent photodisproportionation, tautomerization, and dimerization. Similar irradiation underhoxygen led principally to nitrate and nitro compound formation. The disproportionation of N-(4-nitrosohexyl)acetamide was shown to occur by photodissociation of the C-nitroso monomer to the alkyl radical and nitric oxide. Under an oxygen atmosphere, those C-nitroso compounds which could undergo facile photodissociation were quickly oxidized to nitrates. As a result, mixtures of the corresponding cis- and trans-C-nitrates were obtained from the anti-dimer of trans-1-nitroso-2-chlorocyclohexane. The anti-dimer of trans-1-nitroso-2-piperidinocyclohexane was photolytically tautomerized to the corresponding oxime under nitrogen and was oxidized chiefly to the C-nitro compound under oxygen; the two processes obviously share a common intermediate. Mechanisms for these photoprocesses are suggested.
The Dehydrogenation and Dehydration of 2-Propanol Vapor on Manganese Ferrite
Authors: McCaffrey Eugene Francis , Ross Robert Anderson
Published: May 2006

The dehydrogenation and dehydration of 2-propanol on manganese ferrite has been studied between 306 and 362 °C. The selectivity for dehydrogenation was constant throughout the temperature range. At 362 °C a trace of condensation of the alcohol to mesityl oxide was detected, < 0.1% v/v of the reaction products.
Further Studies of γ-Irradiated Propylene Carbonate Glasses
Authors: Shaede Eric A. , Symons Martyn C. R.
Published: May 2006

An earlier postulate, that physically trapped electrons (et−) are responsible for a narrow e.s.r. singlet at g = 2.0028 formed by exposure of glassy propylene carbonate to 60Co γ-rays at 77°K, is re-examined. An alternative, that propylene carbonate radical anions are formed, in which the extra electron is largely confined to an antibonding orbital on the carbonate moiety, is favored. The primary new evidence for this anion is the detection of satellite e.s.r. lines which were lost on bleaching or thermal decay of the central line, and which occurred in the correct: field regions to be assigned to 13C hyperfine structure from the carbonate carbon of the anion.The complicated set of proton hyperfine lines is now assigned largely to the radical 1 and the mechanisms by which this radical may be formed are discussed. The previously observed temperature dependence of the proton hyperfine features can now be understood in terms of thermal restrictions on the motions of the methyl group and the adjacent methylene protons.
A General Method of Calculating the Water Activity of Supersaturated Aqueous Solutions from Ternary Data
Authors: Sangster J. , Teng T. T. , Lenzi F.
Published: May 2006

Recently developed methods of predicting water activities of multicomponent aqueous solutions use binary data. At high concentrations these methods are limited inasmuch as they require binary data beyond the solubility limit of individual solutes. A method is proposed whereby ternary water activity data may be used to calculate water activities of supersaturated binary solutions. The new method is compared with two extrapolation procedures on a known system and gives the best agreement. Values of the water activities for supersaturated solutions of KNO3 (3.8 to 7.6 m) and K2SO4 (0.7 to 2.3 m) at 25 °C are obtained.
Isotropic Nuclear Magnetic Resonance Shifts of Co(II) Complexes with Mixed Ligands
Authors: Eaton D. R. , Chua K. L.
Published: May 2006

Isotropic n.m.r. shifts of several Co(II) complexes involving β-diketonate ligands are reported. A change of substituent on one β-diketonate ligand significantly affects the shifts of protons or fluorine atoms on the other β-diketonate ligand of the same compound. An argument is presented to suggest that these substituent shifts arise predominantly from contact rather than dipolar effects. The pattern of shifts is compared with that previously observed for β-diketone complexes of V(III) and a similar interpretation is proposed.
Binary Transition Metal Dinitrogen Complexes. Part II. Matrix Infrared and Raman Spectra, Structure, and Bonding of Pt(N2)n (where n = 1–3)
Authors: Kündig E. P. , Moskovits M. , Ozin G. A.
Published: May 2006

The products of the cocondensation reactions of Pt atoms with N2 at 4.2–10 °K are investigated by matrix isolation infrared and Raman spectroscopy and are shown to be binary dinitrogen complexes of the form Pt(N2)n. Examination of the reaction products in pure 14N2, in 14N2/15N2, in dilute 14N2/Ar, in 14N2/15N2/Ar as well as 14N2/14N/15N/15N2/Ar matrices establishes the stoichiometries of the complexes to be n = 1–3. Structural assignments can be made for the complexes Pt(N2) and Pt(N2)3 which contain end-on bonded dinitrogen and are found to be similar to the corresponding dinitrogen and carbonyl complexes of nickel and palladium. Pt(N2)2 appears to be the exception in this series of complexes, for which side-on bonded dinitrogen is proposed.On the basis of the Cotton–Kraihanzel force field of approximation and the isotope intensity sum rules, isotopic frequencies are computed for the NN stretching modes of the individual complexes and isotopic absorption intensities for Pt(N2)3 and are found to be in close agreement with the observed values. In the case of Pt(N2), the scrambled 14N15N isotope data establish that the dinitrogen ligand is bonded to the Pt atom in an end-on fashion. On the basis of its unusual spectroscopic behavior Pt(N2)2 is proposed to have sideways bonded dinitrogen ligands. Pt(N2)3 in solid α-N2 is found to be slightly distorted from a regular triangular planar molecule but appears to be regular D3h in solid argon. Calculations show that a substitutional site symmetry of C2 for Pt(N2)3 satisfactorily accounts for all the spectral lines observed for the complex in nitrogen. Comparisons are made within the group of binary dinitrogen complexes M(N2)n where n = 1–3 and with the corresponding binary carbonyl complexes M(CO)n. The relationship between the dinitrogen complexes NiN2, PdN2, and PtN2 and nitrogen chemisorbed on those same metals is discussed.
Effect of Dose on the Yield of Trapped Electrons in Aliphatic Amine Glasses
Authors: Ito Toshiyasu , Noda Shoji , Fueki Kenji , Kuri Zen-Ichiro
Published: May 2006

An electron spin resonance (e.s.r.) and photoconductivity study has been made of the effect of dose on the yield of trapped electrons in -γ-irradiated aliphatic amine glasses at 77 °K. It is shown that the effect of dose on the trapped electron yield can be correlated with matrix polarity.
Aryl Carbanions. A 13C Nuclear Magnetic Resonance Study of Deuterium Exchange in Acenaphthenes and Related Aromatic Hydrocarbons
Authors: Hunter D. H. , Stothers J. B.
Published: May 2006

The base-catalyzed hydrogen–deuterium exchange rates for the aromatic and benzylic centers in acenaphthene, 2,3-dihydrophenalene, 1,8-dimethylnaphthalene, 1,1,2,2,-tetramethylacenaphthene, and diphenylmethane have been determined using 13C n.m.r. The exchange rates serve as a probe of carbanion stability and reactivity, clearly indicating the importance of ring strain effects on carbanion stability.
Synthesis and Structural Studies of the Metal(II) Mercury Tetrathiocyanate Complexes with Lewis Bases
Authors: Makhija R. , Pazdernik L. , Rivest R.
Published: May 2006

Complexes of the type MHg(SCN)4•2L, where M = Mn2+ to Zn2+ and Cd2+ and L = THF or Py, have been synthesized and characterized by spectroscopic methods. The thiocyanato groups are bridging between M2+ and Hg2+ whereas the donor atom of the ligand is coordinated to M2+ which now attains octahedral configuration. Definite shifts in certain absorption bands of the ligands upon coordination to M2+ are correlated to the formation constant of the metal atom involved in coordination. Electronic spectral data as well as magnetic measurements show that the M2+ is a high spin species in an octahedral environment. The X-ray powder photographs indicate that Co2+ and Zn2+ complexes are isostructural and also most probably are Mn2+ and Fe2+. Tentative assignments for metal–NCS, M–ligand, Hg—S, and L—M—L absorption bands are discussed.
Structure of the Capsular Polysaccharide of Klebsiella K-type 20
Authors: Choy Yuen-Min , Dutton Guy G. S.
Published: May 2006

Methylation, periodate oxidation, and partial hydrolysis studies on the capsular polysaccharide, and on the carboxyl reduced polymer, of Klebsiella K20 show the structure to consist of a repeating unit[Formula: see text]The anomeric linkages were determined by p.m.r. spectroscopy of the carboxyl reduced polysaccharide, and periodate degraded polysaccharides. The p.m.r. spectroscopy of the original polysaccharide also showed the presence in the polysaccharide of one O-acetyl group per eight sugar residues.
Nucleophilic Attack on Some Isothiazolium Salts
Authors: Mckinnon David M. , Hassan Mohamed E.
Published: May 2006

A variety of isothiazolium salts has been prepared and allowed to react with sodium benzoylacetate. 2-Benzoylthiophenes are obtained, suggesting that the position of initial nucleophilic attack is at the sulfur atom of the heterocyclic cation. Reaction with hydrogen sulfide gave acyclic reduction products, or 1,2-dithiole derivatives, depending on the type of substituent on nitrogen in the isothiazolium salts.