bluuebunny/crossref_metadata_2025 huggingface dataset:
Carbon monoxide yields in the radiolysis of carbon dioxide at very high dose rates
Authors: Willis C. , Boyd A. W. , Bindner P. E.
Published: May 2006

Carbon dioxide has been irradiated with electron pulses at a dose rate of 2 × 1027 eV g−1 s−1. The measured carbon monoxide yield is G(CO) = 7.8 ± 0.3. Addition of SF6, an electron scavenger, reduces this yield to G(CO) = 4.8 which is the same, within the experimental error, as the low dose rate yield G(CO) = 4.5 ± 0.5. The effect of SF6 and the difference between the high and low dose rate yields is explained by suppression of dissociative neutralization of the C2O4+ ion.
2-D-Hydroxyhexadecanoic acid: a metabolic product of the yeast Hansenulasydowiorum
Authors: Vesonder R. F. , Stodola F. H. , Rohwedder W. K. , Scott D. B.
Published: May 2006

A new species of yeast, Hansenulasydowiorum, excreted free α-hydroxy fatty acids when grown on glucose solution. The major component, 2-D-hydroxyhexadecanoic acid, was identified by the mass spectrum of its methyl ester.
Photolysis of cyclopentanone
Authors: Blades A. T.
Published: May 2006

The effect of wavelength and pressure on the distribution of products has been studied in the photolysis of cyclopentanone and cyclopentanone-2,2,5,5-d4. At low pressures, C2D4 and C2H4 are formed in addition to the expected high pressure product C2H2D2, confirming the intermediate formation of excited cyclobutane. The high pressure ratio of cyclobutane to ethylene is attributed to alternate reactions of the tetramethylene diradical which have equal energy sensitivity, and some evidence is presented for a further mechanism of ethylene formation at short wavelengths. Evidence is also presented for the formation of cyclobutane and ethylene following thermal re-excitation of the precursor of 4-pentenal.
Physicochemical properties of some new 1,5- and 5,5-alkyl-substituted barbituric acids
Authors: Neville G. A. , Avdovich H. W. , By A. W.
Published: May 2006

The synthesis of six new barbituric acids 1b, 3a, 4b, 5, and 6b, including the novel 5-hydroxy derivative 3b, is reported together with spectroscopic data (proton magnetic resonance, ultraviolet, and infrared) for these and for five related known barbiturates for which such data is lacking. An interesting occurrence of non-equivalence of the N-1 and N-3 CH2(Et) protons in 3b is discussed.
Studies of cobalt(III) complexes of thiosemicarbazide
Authors: Sun Kenneth K. W. , Haines Roland A.
Published: May 2006

cis and trans geometric isomers of low spin octahedral cobalt(III) complexes containing either thiosemicarbazide (Htsc) or its anion (tsc) have been prepared and electronic spectra are presented and discussed. For the ionic form [Co(Htsc)3]3+ both isomers were resolved and absolute configurations were assigned on the basis of optical rotatory dispersion and circular dichroism measurements. The interconversion of these optically active complex ions in aqueous solution was studied and a bond rupture mechanism is proposed to account for the observed inversion and isomerization.
Quinoline N-oxides and hydroxamic acids with antibacterial properties
Authors: Coutts R. T. , Hindmarsh K. W. , Myers G. E.
Published: May 2006

A number of quinoline N-oxides have been prepared and oxidized by means of lead tetraacetate to quinoline hydroxamic acids (i.e. derivatives of 1-hydroxy-2(1H)-quinolone). Contrary to the findings of other investigators, 1-hydroxy-4-nitro-2(1H)-quinolone (2e) is obtained by treating 4-nitroquinoline 1-oxide with lead tetraacetate. Quinolines with a methyl group in the 8-position could not be oxidized to N-oxides with hydrogen peroxide.The antibacterial properties of the hydroxamic acids and some of the N-oxides were evaluated against S. aureus and E. coli.
Surface studies by attenuated total reflection spectroscopy. I. Corona treatment of polypropylene
Authors: Carlsson D. J. , Wiles D. M.
Published: May 2006

The chemical changes produced by brief corona treatments of polypropylene films have been studied by attenuated total reflection (a.t.r.) infrared spectroscopy. Surface layers of different thicknesses were investigated by varying the reflection conditions. Changes in the surface spectra were quantitatively compared by the use of an internal correction method which compensated for irreproducible experimental conditions. Corona treatment in a nitrogen atmosphere produced thin surface layers (less than 500 Å) of C—C unsaturation. Nitrogen derivatives were not detected in the surface. Corona treatment in oxygen caused surface changes which depended markedly on the corona conditions owing to the generation of ozone in the discharge zone. At low ozone concentrations, both unsaturation and oxidation were found in surface layers of under 500 Å thickness. At higher ozone concentrations, extensive oxidation occurred at appreciable depths into the polymer (several microns). An oxygen corona appears to result in essentially the same surface changes as does a nitrogen corona treatment, followed by exposure to ozone.
Organobismuth compounds. I. Studies on triphenylbismuth(V) derivatives, Ph3BiX2
Authors: Goel R. G. , Prasad H. S.
Published: May 2006

Triphenylbismuth(V) acid derivatives of the type, Ph3BiX2, where X = halide, nitrate, cyanate, acetate, haloacetate, or cyanoacetate have been prepared. Infrared spectra (4000 to 200 cm−1 region), electrical conductances, and molecular weights of these compounds have been studied to elucidate their structural features and chemical constitution. The molecular weight and conductance data show that these compounds behave as molecular species in benzene or nitromethane. The infrared spectroscopic results also indicate non-ionic five-coordinate structures. Bi—X stretching frequencies have been assigned for the difluoride, dichloride, dinitrate, dicyanate, and diacetate. These frequencies occur in the region 410–240 cm−1.
The pressure dependence of benzyl chloride solvolysis in aqueous acetone and aqueous dimethylsulfoxide
Authors: Macdonald Digby D. , Hyne J. B.
Published: May 2006

First-order rate constants for the solvolysis of benzyl chloride in a series of aqueous acetone and aqueous dimethylsulfoxide (DMSO) mixtures at 50.100 °C and at various pressures in the range 1–4083 atm are reported. Volume of activation, calculated from the rate/pressure data, is found to exhibit extremum behavior with varying solvent composition in both solvent systems. The activation volumes are dissected into their initial state and transition state contributions by determining the "instantaneous" volumes of solution of benzyl chloride in the solvent systems. The contributions of both the initial state and the transition state to the behavior of the activation volume as a function of solvent composition are discussed.
Relative reactivities of dihydrophenazine and dihydrophenazonium radicals in electron-transfer to an azobenzene
Authors: Reeves Richard L.
Published: May 2006

A kinetic study of the electron-transfer reaction between a model azobenzene and dihydrophenazonium ion-radical and dihydrophenazine was carried out in 0.2 N sulfuric acid in 50 v/v aqueous acetonitrile. The second-order rate constant for the dihydrophenazine is greater than that of the ion-radical by a factor of 104. It is shown that in solutions in which the ion-radical is the predominant species, the principal electron-transfer agent is the dihydrophenazine formed by dismutation of the radical.
Enthalpies of reaction of zirconium and molybdenum tetrachlorides with pyridine, tetrahydrofuran, and tetrahydrothiophene
Authors: Westland A. D. , Uzelac V.
Published: May 2006

Enthalpies of addition were determined calorimetrically for the crystalline complexes MCl4•2L where M = Zr and L = pyridine or M = Mo and L = pyridine, tetrahydrofuran, or tetrahydrothiophene. Molybdenum(IV) is a significantly better acceptor than zirconium(IV) toward pyridine and tetrahydrofuran but not toward tetrahydrothiophene. A possible explanation for this is discussed.
Intermolecular forces in gaseous ammonia and in ammonia – nonpolar gas mixtures
Authors: Lee C. S. , O'Connell J. P. , Myrat C. D. , Prausnitz J. M.
Published: May 2006

Intermolecular potential parameters for ammonia have been determined for the Stockmayer–Kihara function using experimental second virial coefficient, diffusivity and viscosity data of binary mixtures with argon, methane, nitrogen, and oxygen. The parameters U0/k = 215 °K, σ(core-to-core) = 2.70 Å and a* = 0.2 reproduce essentially all of the data nearly within experimental error and accurately reproduce pure ammonia transport properties. Upon considering both physical and chemical contributions to the second virial coefficient of ammonia, the apparent standard-state hydrogen-bond enthalpy for chemical dimerization is −3.2 kcal/mole while the vibrational entropy change is 20.2 cal/mole °K, indicating weak association.
Acid dependence and ion pairing in the anation reactions yielding iron(III) monosulfate
Authors: Baker F. L. , Smith W. MacF.
Published: May 2006

Stopped-flow studies of the kinetics of the a nation reaction yielding iron(III) monosulfate indicate a significant dependence of rate constant on acidity and also a dependence on iron concentrations. This is consistent with association constants for outer ion pair formation between the reactants which have about three times the Fuoss values.
Copper(II) derivatives of the stereochemically adaptive ligands 1,2-bis(2′-pyridyl)ethane and bis(2-pyridyl)disulfide
Authors: Keeton M. , Lever A. B. P. , Ramaswamy B. S.
Published: May 2006

Tetrahedral, square, square pyramidal, and tetragonally distorted octahedral complexes of copper(II) with the title ligands are characterized by electronic and vibrational spectroscopy (at ambient and low temperature) and magnetism. The infrared spectra are utilized to infer information about the conformation of the ligands in these complexes. The variation in structural types observed is believed to be a consequence of the stereochemical adaptability of these ligands to the electronic demands of the metal ion.
The effect of pressure on the hydrolysis equilibria of aqueous metal ions
Authors: Swaddle T. W. , Kong PI-Chang
Published: May 2006

The molal acid dissociation ("hydrolysis") constant Km of aqueous hexaaquochromium(III) ion, at 25.0° and ionic strength 0.5 m, has been determined spectrophotometrically as a function of pressure P up to 3 kbar. Km increases with P (kbar) in accordance with the equation[Formula: see text]The molal volume change is −3.8 ± 0.7 cm3 mole−1, and the enthalpy and entropy changes at 1 bar are 9.3 kcal mole−1 and 12.1 cal deg−1 mole−1. Compressions of 0.1, 0.5, and 1.0 M aqueous perchloric acid, lithium perchlorate, and sodium perchlorate up to 4 kbar have also been measured.
Radiolysis of liquid hydrocarbons containing deuterium sulfide
Authors: Stone J. A. , Holland P. T.
Published: May 2006

The radiolysis of hydrocarbons containing dissolved D2S leads to HD, D2, and H2 formation, the total hydrogen yields being greater than those in the absence of D2S. A limiting yield of HD is attained at low D2S concentrations (~5 mole%) in all solvents studied. This limiting yield is equal to G(H•) in ethane at 195°K but not in c-C6H12 at 298°K when G(HD) is much greater than accepted values of G(H•). D2S behaves as both an electron and a positive ion scavenger, most of the D2 and probably some of the HD being formed in these processes. The use of D2S to determine H atom and ion yields in irradiated alkanes is not recommended.
Nuclear spin – lattice relaxation and molecular association in acetone/water mixtures
Authors: Reeves L. W. , Yue C. P.
Published: May 2006

Nuclear spin – lattice relaxation times T1 of protons have been measured as a function of concentration at room temperature for H2O/CD3COCD3 and CH3COCH3/D2O solutions. The results show that T1 reaches a minimum at ~ 0.8 mole fraction of water in both solutions. This is interpreted in terms of molecular association between water and acetone molecules by hydrogen bonding.Theoretical values for (1/T1)rot and (1/T1)trans are also calculated from rotational and translational correlation times using Stokes' model and the microviscosity model. Comparison with the experimental T1's shows that both models are inadequate to describe the system.Contributions to the overall (1/T1) from (1/T1)rot and (1/T1)trans are analyzed. It is found that the rotational motion dominated the relaxation process. The use of two different interaction parameters λ and ηe to describe molecular association is discussed.
The H− acidity function for dimethylformamide–water
Authors: Buncel E. , Symons E. A. , Dolman Douglas , Stewart Ross
Published: May 2006

The H− acidity function has been determined for N,N-dimethylformamide–water mixtures containing tetramethylammonium hydroxide by the Hammett indicator method. Basicity in the aqueous dimethylformamide system exceeds that in aqueous tetramethylenesulfone but is slightly less than in aqueous dimethylsulfoxide, at equivalent molar compositions of solvent and base. However, the basic aqueous dimethylformamide solvent system is only of limited utility as a result of reaction of hydroxide ion with the dimethylformamide.
Mass spectrometric studies of chemical reactions in shock waves. Part II. The thermal decomposition of diazomethane
Authors: Dove J. E. , Riddick J.
Published: May 2006

The thermal decomposition of CH2N2, highly diluted in Kr, has been studied in shock waves by using time-of-flight mass spectrometry to follow concentration changes in the reacting gas. Observations were made at pressures 45 to 95 Torr and temperatures 820 to 1200°K. The principal products of reaction are C2H4, C2H2, and N2. The primary step appears to be a second order unimolecular decomposition of CH2N2 into CH2 and N2; for this step, log k = (9.61 ± 0.21) − (15 800 ± 1 000)/2.303RT(cal mole−1 and cm3 mole s units.) Some decomposition of CH2N2 into HCN and NH is also indicated. The formation of C2H2 is believed to occur through vibrationally excited C2H4, formed by reaction between CH2 and CH2N2. Calculations using the R.R.K.M. theory indicate that 50 + 10% of the energy of this reaction appears as vibrational energy of the product C2H4.
Spectra of cobalt(II) and nickel(II) in molten lead, stannous, and bismuth chlorides
Authors: Fung K. W. , Johnson K. E.
Published: May 2006

From measurements of electronic spectra it is deduced that cobalt(II) is tetrahedrally coordinated in molten PbCl2, SnCl2, and BiCl3, whereas nickel(II) adopts a coordination in PbCl2 and SnCl2 which is close to octahedral. NiCl2 is insoluble in BiCl3 and is formed by the reaction of NiS and BiCl3 whereas CoS is soluble in BiCl3. Solutions of Pd(II), Pt(II), Rh(III), and Ir(III) may be prepared in molten PbCl2 but the spectra do not assist in assigning the coordination of the solute ions.
Organic sulfur compounds. VII. Some reactions of benzothiazine hydroxamic acids
Authors: Coutts R. T. , Matthias Sharon J. , Mah E. , Pound N. J.
Published: May 2006

Treatment of (3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid (1a) with sodium hydroxide yields the corresponding lactam, i.e. (3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid, together with the α,β-unsaturated acid, 3,4-dihydro-3-oxo-2H-1,4-benzothiazine-Δ2,α-acetic acid. The 6-methyl- and 6-bromo-derivatives of 1a behaved similarly when reacted with sodium hydroxide but when 3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazine was so treated a more complex reaction occurred.Methyl (6-bromo-3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazin-2-yl)acetate was also treated with hydrochloric acid. The two products isolated were (6-bromo-3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid and (6-bromo-7-chloro-3,4-dihydro-3-oxo-2H-1,4-benzothiazin-2-yl)acetic acid.The action of hydrochloric acid on 3,4-dihydro-4-hydroxy-7-methyl-3-oxo-2H-1,4-benzothiazine also gave two products. One was the corresponding lactam; the other was unexpected and has been tentatively identified as bis[2-(3,4-dihydro-7-methyl-3-oxo-2H-1,4-benzothiazine].
Spin–orbit relaxation of Hg(63P1) by various gases
Authors: Vikis A. C. , Torrie G. , Roy D. J. Le
Published: May 2006

The enhanced rate of the mercury photosensitized decomposition of C2H4 under incomplete quenching conditions caused by various added gases (1) has been used to obtain quantum yields, [Formula: see text], for the spin–orbit relaxation process [Formula: see text]. Values of [Formula: see text] for C(CH3)4c-C3H6, NH3, ND3, H2O, and D2O were all > 0.5 while CO2 quenches predominately to the ground state.
Mesquite gum. I. The 4-O-methylglucuronogalactan core
Authors: Aspinall G. O. , Whitehead C. C.
Published: May 2006

A re-examination of mesquite gum has shown that partial hydrolysis of the gum furnishes a mixture of acidic oligosaccharides including 6-O-(4-O-methyl-β-D-glucopyranosyluronic acid)-D-galactose (1), 4-O-(4-O-methyl-α-D-glucopyranosyluronic acid)-D-galactose (2), 6-O-(β-D-glucopyranosyluronic acid)-D-galactose (3), O-(4-O-ethyl-β-D-glucopyranosyluronic acid)-(1→6)-O-β-D-galactopyranosyl-(1→6)-D-galactose (4), and O-(4-O-methyl-α-D-glucopyranosyluronic acid)-(1→4)-O-β-D-galactopyranosyl-(1→3)-D-galactose (5). A series of degradations of the gum affords successively, arabinose-free degraded gum A, carboxy-reduced degraded gum A, and degraded gums B and C. Degraded gum C contains a high proportion of 1→3′ linked β-D-galactopyranose residues. The structure of the 4-O-methylglucuronogalactan core of the gum is re-assessed in the light of these and other results.
Mesquite gum. II. The arabinan peripheral chains
Authors: Aspinall G. O. , Whitehead C. C.
Published: May 2006

Autohydrolysis of mesquite gum affords a series of arabinose-containing oligosaccharides [A–Q] whose structures have been established. It is concluded that the majority of these oligosaccharides originate from peripheral chains in the gum containing the following sugar sequences:(1) α-L-Araf-(1 → 6)-α-D-Galp-(1 → 3)-α-L-Araf-(1 → 3)-L-Araf-(1- and(2) β-L-Araf-(1 → 2)-β-L-Araf-(1 → 2)-β-L-Araf-(1 → 2)-β-L-Araf-(1 → 2)-α-L-Araf-(1 → 4)-β-L-Arap-(1 → 3)-L-Araf-(1-.
The Electronic Spectra of Tetragonal Chromium(III) Complexes
Authors: Keeton M. , Chou B. Fa-Chun , Lever A. B. P.
Published: May 2006

Methods for processing the electronic spectra of tetragonal chromium(III) complexes are briefly reviewed. New criteria for assigning the spectra of these complexes are introduced and the data processed to yield a series of crystal field and molecular orbital parameters. The validity of these are discussed with particular reference to the apparent Π bond contribution in the chromium ligand bonds. It is concluded that the bonding is better described in ionic rather than covalent terms.
Application of Paramagnetic Shift Reagents in Nuclear Magnetic Resonance Studies of Complex Alcohols and Amines
Authors: Gillies Elaine , Szarek W. A. , Baird M. C.
Published: May 2006

The effects of Co(acetylacetonate)2, Ni(acetylacetonate)2, and Cu(ethyl acetoacetate)2 on the nuclear magnetic resonance spectra of a variety of alcohols and amines have been studied. Changes are produced in the spectra, which are useful for assigning the signals.
Spiroalkylation of some Homophthalimides and Oxindoles with 1-Bromo-2-chloroethane
Authors: Horning D. E. , Lacasse G. , Muchowski J. M.
Published: May 2006

The base-induced alkylation of 4-unsubstituted homophthalimides with 1-bromo-2-chloroethane produced the spirocyclopropane compounds 4. The structures of these compounds were supported by their spectral properties and by their susceptibility towards cleavage of the three-membered ring with secondary amines.Under similar conditions, 3-unsubstituted oxindoles also yielded spirocyclopropane compounds 7, but 4-hydroxycarbostyril gave the 4-O-alkylated compound 8 instead.
Oxydation lente du cétène en phase gazeuse. I. Réaction à "hautes températures"
Authors: Michaud Pierre , Ouellet Cyrias
Published: May 2006

The slow combustion of ketene in the gas phase was studied by the static method in a 30 × 4 cm Vycor cylinder between 280 and 500 °C at pressures above 20 mm Hg. Extending the work of Barnard and Kirschner, we have established the existence of two types of slow combustion of ketene corresponding to two temperature ranges. In this first paper, we describe the kinetic and analytical results obtained in the higher temperature range (380–500 °C). The reaction is autocatalytic and shows a low temperature coefficient corresponding to a few kilocalories per mole. The main products are carbon monoxide, formaldehyde, water, and carbon dioxide. No ethylene was detected. We suggest a chain reaction in which formaldehyde is the intermediate responsible for degenerate branching:[Formula: see text]
Polarographic Observations of some Iron Organometallic Compounds in Acetonitrile
Authors: Breckenridge J. H. , Vandenborn H. W. , Harris W. E.
Published: May 2006

Polarography in acetonitrile is useful for the study of the electrochemical behavior of organometallic compounds because acetonitrile is a suitable solvent for this class of compounds and provides a wide potential range over which their electrochemical behavior can be investigated. This inquiry was undertaken to enhance the understanding of the chemistry of these compounds. The polarographic behavior of three related iron compounds was studied and attempts were made to identify the products of the electrochemical reactions.
Investigations of Paramagnetic Centers Produced by Tritium β-Particle Irradiation. I. The Cd(I) Cation in Single Crystals of Calcium Tetraacetato Cadmium (II) Hexahydrate
Authors: Eachus R. S. , Herring F. G.
Published: May 2006

The Cd(I) center has been produced by both tritium β-particle irradiation and by γ-irradiation. The tritium was introduced as water of crystallization in calcium tetraacetato cadmium(II) hexahydrate in the form of THO. It is found that both forms of irradiation lead to the same center. The orientation of the hyperfine components of the Cd(I) center throws some light on the possible mechanism of its formation.
Proton Magnetic Resonance Study of the Conformational Equilibria in Some Substituted N-Acetylpyrrolidines
Authors: Wong C. M. , Buccini J. , Schwenk R. , Raa J. Te
Published: May 2006

In the p.m.r. spectra of eight N-acetyl-2-(p-methoxybenzyl)-pyrrolidines, the acetamido methyl group gives rise to two peaks in the range 7.7–8.5 τ Compounds 9 and 10 also exhibit two peaks for the acetoxy methyl group in the same range. When the samples were heated, the pairs of peaks coalesced to give singlets. These results are interpreted as evidence for the existence of conformational equilibria.
Synthesis and Properties of 5-Hydroxymethyl-2′-deoxyuridine and its α-Anomer
Authors: Gupta V. S. , Bubbar G. L.
Published: May 2006

The synthesis and properties of 5-hydroxymethyldeoxyuridine (6) and its α-anomer 7 are described. Treatment of 5-hydroxymethyluracil (2) with trimethylchlorosilane in the presence of triethylamine gave 2,4,5-tris(trimethylsilyl)-5-oxymethyluracil (3) in excellent yield (92%) which, upon condensation with 3,5-di-(O-p-toluoyl)-2-deoxy-D-ribofuranosyl chloride in acetonitrile at room temperature, furnished an anomeric mixture of substituted nucleosides β-anomer (4) and α-anomer (5) in high yield 90% (by a fusion method (12) yield of blocked nucleosides was 70%). Compound 4 was the major product formed by both methods and was recovered as a crystalline solid in high yield. However, condensation of 3 with chlorosugar in benezene with mercuric chloride as a catalyst at room temperature gave a mixture of protected nucleosides; the amount of 5 formed was appreciably higher (34%) and was isolated as a microcrystalline solid from mother liquors in low yield (without the catalyst nucleosides were formed in low yield 30%). Removal of the blocking groups by alcoholysis gave 6 and 7 in high yields. The structure was confirmed by n.m.r. studies, u.v. and i.r. absorption spectra, elemental analysis, and by conversion of 4 to β-thymidine (8).
The Effect of Substituents on Geminal Proton–Proton Coupling Constants; a Conformational Dependence. II
Authors: Fraser Robert R. , Renaud Roger N.
Published: May 2006

The effect of para-substituents on the geminal coupling constants in benzylic methylene groups has been studied as a function of the conformation at the benzene—CH2 bond. The slopes of Hammett plots of Jgemvs. σ are large (−1.6 to −1.9) when the geometry permits a hyperconjugative interaction between the benzene ring and the methylene group but negligible (+ 0.2) when this interaction is geometrically restricted. The effect of a change in electronegativity of the group attached to the methylene carbon has also been investigated. The change in the slope, ρ, from −1.7 to −1.6 on protonation of the nitrogen attached to the methylene group in a series of isoindolines shows this effect to be extremely small. Solvent effects on ρ are also very small. The potential of this J − σ relation for conformational analysis of benzyl groups is discussed in comparison with existing methods.
Reaction of Hydrogen Atoms with Carbon Suboxide
Authors: Demchuk Nick , Gesser H. D.
Published: May 2006

The gas phase reaction of hydrogen atoms with carbon suboxide was studied over the temperature range of−96 to 235 °C and was found to proceed via a chain reaction. The products found were CH4, CO, CH2CO, C2H6, (CHO)2, and polymer. A mechanism is proposed and the chain reaction is explained by the intermediate formation of ketene and the formyl radical.
H2O, HDO, and CH3OH Infrared Spectra and Correlation with Solvent Basicity and Hydrogen Bonding
Authors: Glew D. N. , Rath N. S.
Published: May 2006

A study has been made of the infrared O—H bands for CH3OH, DOH, and H2O in solution and of their correlation with hydrogen bonding and solvent basicity. Infrared bands for the three fundamentals and the first bending overtone of H2O and for the O—H stretching fundamentals of DOH and CH3OH have been measured between 30 and −40 °C in a solvent range extending from weakly interacting fluorocarbons to strongly hydrogen-bonding organic amines. The O—H stretching bands for the weakly acidic solutes CH3OH, DOH, and H2O are mostly Lorentzian in shape and move to lower frequencies with higher extinctions in the more basic solvents. Many correlations are found between the stretching frequencies and band areas, and between the frequencies and solvent basicity. Monofunctional CH3OH is found to be a stronger acid and forms stronger hydrogen-bonds with a given base than do the doubly bonded DOH and HOH which show equal dibasic acid strengths.The wide, overlapped, fundamental stretching bands for H2O strongly hydrogen-bonded to the tertiary amines and for ice have been partially resolved and unequivocally assigned, showing that there is no cross-over of the ν 3 and ν1 bands despite the strong hydrogen-bonding.At higher temperatures in solvents containing both hydrophobic and strongly basic groups water was found with the lower Cs type symmetry, in which unbonded O—H groups gave sharp bands in the 3680–3650 cm−1 region in addition to the wide hydrogen-bonded bands at lower frequencies.
Nonequilibrium Thermodynamics in Chemical Kinetics
Authors: Anderson M. L. , Boyd R. K.
Published: May 2006

The description of chemical reaction rates, in terms of the language of nonequilibrium thermodynamics, is compared with the conventional language of chemical kinetics. It is concluded that the formalism of nonequilibrium thermodynamics possesses considerable disadvantages, even in the regime where the rate is a linear function of affinity; this conclusion also holds for cases where chemical rates are coupled to diffusion processes. Some of the difficulties involved are illustrated using the experimental data of Nebeker and Pings (28).
The 19F and 1H Nuclear Magnetic Resonance Spectra of 2-Thienylcarbonyl Fluoride and 2-Thiazolylcarbonyl Fluoride
Authors: Schaumburg Kjeld
Published: May 2006

The preparation of 2-thienylcarbonyl and 2-thiazolylcarbonyl fluorides from the corresponding carboxylic acids is described. The n.m.r. spectroscopic parameters are determined and compared with experimental data for similar systems. Theoretical values for the coupling constants have been obtained in the CNDO/2 approximation and they are compared with the experimental data.
Photochlorination of Perfluorocyclobutene
Authors: Alberto Z. R. , Cosa J. J. , Vallana C. A. , Staricco E. H.
Published: May 2006

The kinetics in the gas phase of the photochemical reaction between perfluorocyclobutene and chlorine was studied between 10 and 70 °C. The system was irradiated with light of 4360 Å. The rate of photochlorination was measured under full and intermittent light. The Arrhenius parameters for the reaction:[Formula: see text]are: A3 = (2.9 ± 1.1) × 108 1 mol−1 s−1 and E3 = 4.64 ± 0.03 kcal/mol and for[Formula: see text]the constant rate value is: k4 = (7.23 ± 4.3) 21 × 108 1 mol–1 s−1.
A 19F Nuclear Magnetic Resonance Study of Halogen Exchange between Antimony Pentafluoride and Inorganic Chlorides. Complexes of Antimony and Arsenic Pentafluorides with Carbonyl Fluoride
Authors: Bacon J. , Dean P. A. W. , Gillespie R. J.
Published: May 2006

19F nuclear magnetic resonance (n.m.r.) has been used to study the reactions occurring in the systems SbCl5–SbF5–SO2ClF, SO2Cl2–SbF5–SO2ClF, COF2–SbF5–SO2ClF, COF2–AsF5–SO2ClF, and COClF–SbF5–SO2ClF. Ionization occurs in SbCl5–SbF5–SO2ClF, yielding antimony chloro- and chloro-fluorocations and antimony polyfluoroanions. Donor-acceptor complexes are formed between SbF5 and SO2Cl2, COF2 or COClF at low temperatures and also between AsF5 and COF2. In all the complexes the ligand is oxygen-bonded. At higher temperatures halogen exchange and ionization occurs in SO2Cl2–SbF5–SO2ClF and COClF–SbF5–SO2ClF giving SO2ClF and COF2 complexes, respectively, together with antimony cations and polyfluoroanions. The alkyl chloride –SbF5 reaction is also shown to give chlorine-containing cations of antimony.
Some Aspects of the Mass Spectra of.N-Nitrosamines
Authors: ApSimon J. W. , Cooney J. D.
Published: May 2006

The mass spectra of seven cyclic N-nitrosamines were examined for characteristic fragmentation patterns. Accurate mass measurements on three of the compounds indicated that the M-17 and M-30 peaks resulted from molecular ion losses of •OH and •NO respectively. The loss of • OH was rationalized in terms of a McLafferty-type rearrangement.
On the Distinction between Reaction Fluxes and Phenomenological Rate Constant
Authors: Boyd R. K.
Published: May 2006

The physical interpretation of the phenomenological rate constants of chemical kinetics is examined. For perfect gas systems, the traditional view of the rate constants for elementary reactions as one-way reaction fluxes is compared with a more recent interpretation (3) in terms of more complicated functions; it is concluded that, for real systems, the former view is a special case of the latter, while for systems in which the phenomenological rate equation is exact, the rate constants are shown to be one-way fluxes.In any given system, the applicability of the special interpretation is a function of the detailed nature of the transport matrix, which is generally unknown; practical implications of these ideas are presented. For systems other than perfect gases, the problem is complicated by the absence of well-defined molecular states; however, it is suggested that the flux interpretation is the most reasonable.
Spectrofluorometric Studies. X. The Photochemistry of Pentafluorobenzene
Authors: Lem S. L. , Semeluk G. P. , Unger I.
Published: May 2006

The vapor phase photochemistry of pentafluorobenzene has been examined at a variety of exciting wavelengths starting at 2540 Å and extending to 2780 Å. Most of the studies were carried out at 2620, 2660, and 2700 Å. Below 2600 Å pentafluorobenzene does not exhibit any detectable fluoroscence, above 2600 Å a very weak fluorescent emission was observed. Addition of biacetyl does not markedly reduce the fluorescent yield, while addition of cyclohexane, CO2, and cis-butene-2 causes an increase in the fluorescent yield. The triplet yield of pentafluorobenzene excited at 2620, 2660, and 2700 Å, measured by the sensitized emission of biacteyl technique, is also very low and is increased by the addition of cyclohexane, CO2, and cis-butene-2. cis-Butene-2 is the most effective gas, of the three examined, in increasing the fluorescent and triplet yields of pentafluorobenzene. The fate of the majority of pentafluorobenzene molecules excited in the 2600 Å region is unknown.
The Crystal Structure of [Rh(f6fos)2]+[cis-(CO)2RhCl2]−
Authors: Einstein F. W. B. , Hampton C. R. S. M.
Published: May 2006

The crystal structure of di(1,2-bis(diphenylphosphino)hexafluorocyclopentene) rhodium(I) cis-dicarbonyldichlororhodate(I), [Rh(f6fos)2][cis-Rh(CO)2Cl2] has been determined from three-dimensional X-ray scintillation counter data. The structure has been refined by full-matrix least-squares techniques to a conventional R factor of 8.8%. The salt crystallizes in the tetragonal space group I41/a with eight formula units in a cell of dimensions a = 17.722(1) Å and c = 36.773(4) Å. Each ion is nearly square planar and has a crystallographic two-fold axis passing through the rhodium atom. The two independent Rh—P distances are 2.282(6) and 2.300(6) Å, and the bite of the chelating ditertiary phosphine, f6fos, is 3.111(8) Å as measured by the intra-ligand P—P distance.
Déplacement induit par un lanthanide en résonance magnétique nucléaire. Une application à un problème stéréochimique
Authors: Bélanger P. , Freppel C. , Tizané D. , Richer J.-C.
Published: May 2006

Shifts induced by tris(dipivalomethanato) praseodymium (III) have been applied to the determination of the stereochemistry of cis and trans 4-tert-butyl 1,2,2-trimethyl cyclohexanols. Observed shifts were at higher field than tetramethylsilane and a linear relationship has been established between the induced shifts and the cube of reciprocal distance metal-hydrogen.
11-Hydroxy-trans-8-dodecenoic Acid Lactone, a 12-Membered-Ring Compound from a Fungus
Authors: Vesonder R. F. , Stodola F. H. , Wickerham L. J. , Ellis J. J. , Rohwedder W. K.
Published: May 2006

The 12-membered lactone of 11-hydroxy-trans-8-dodecenoic acid is formed when the fungus Cephalosporium recifei NRRL 5161 is grown on glucose solution.
Metal – Aminopolycarboxylic Acid Complexes. I. Studies of Lead(II) and Cadmium(II) Complexes with Diethylenetriaminepentaacetic Acid in Aqueous Solution by Proton Magnetic Resonance Spectroscopy
Authors: Letkeman P. , Westmore J. B.
Published: May 2006

Lead(II) and cadmium(II) each form a 1:1 complex with DTPA. Nuclear magnetic resonance (n.m.r.) spectroscopy was used to show that each complex has three metal–nitrogen bonds and labile metal–oxygen bonds to terminal acetate groups. The latter lead to proton equivalence for the methylene protons of the terminal acetate groups of the lead complex, and near equivalence for those of the cadmium complex. The central carboxylate group is coordinated to the lead but not to the cadmium. Protonation occurs below pH 5.5 for the lead complex and occurs predominantly at a terminal nitrogen atom with consequent breaking of the metal–nitrogen bond. In the cadmium complex protonation occurs below pH 5 at the terminal nitrogen, breaking the metal–nitrogen bond, and also to almost the same extent at the central, uncoordinated carboxylate group. These differences in behavior of the lead and cadmium complexes are attributed to differences in ionic size. Possible structures are proposed and allowances are made for the possibility of coordination number greater than six. In the protonated complexes, structures and interconversion of protonated forms are discussed in the light of the observed simplification of the n.m.r. spectra.
A Study of the Pfeiffer Effect in Systems containing Trisoxalatometallate(III) Complexes and Cinchonine Hydrochloride
Authors: Kan K. T. , Brewer D. G.
Published: May 2006

The Pfeiffer effect was studied in systems containing cinchonine hydrochloride and trisoxalatometallate(III) complexes of Al, Fe, Cr, Co, and Ir. The Pfeiffer rotatory dispersion curves of the Cr and Co complexes show Cotton effects analogous to that observed in the optical rotatory dispersion (o.r.d.) curves of the respective complexes. The source of the Pfeiffer effect in all these systems is attributed either to an association between the complex ion and the optically active species in solution alone, as in the case of the Ir(lII) complex, or to a combination of this association and an "equilibrium shift" between the two enantiomers in solution in favor of one of them, as in the case of the other complexes under investigation.
Trimethylgermanium Nitrate
Authors: Potts D. , Walker A.
Published: May 2006

The spectroscopic and solution properties of trimethylgermanium nitrate have been determined and compared with those of other known Group IV alkyl nitrates. The vibrational spectra show that the nitrato group is covalently bound to the germanium atom in a unidentate manner. Ultraviolet spectra and conductivity measurements indicate that the compound behaves as a 1:1 electrolyte in water and dimethylsulfoxide, but is a non-electrolyte in methyl cyanide, nitromethane, and ethyl acetate. Attempts to prepare methylgermanium trinitrate are also described.
Production of Electrons by Reaction of Sodium with Methanol and Ethanol: Kinetics of their Formation and Subsequent Reactions
Authors: Fletcher J. W. , Richards P. J.
Published: May 2006

In the reaction of sodium with alcohols an electron is generated without the formation of other reactive products. This, therefore, provides an excellent system to study the reactions of the electrons with themselves, with the solvent, and with added scavengers. A mathematical treatment for such formation and reaction has been derived.Evidence for a bimolecular electron reaction was investigated by observing the formation of D2 in the reaction of sodium with ethanol-d1 or methanol-d1, via reaction[Formula: see text]A calculated rate constant for this reaction in ethanol at 25 °C, k = (5 ± 4) × 109 M−1 s−1, similar to that observed for the equivalent reaction in water, is obtained. An isotope effect (α = 2) for the above reaction in both ethanol and methanol is observed. This would indicate the formation of an electron dimer (e−)2 as an intermediate in the formation of hydrogen as has been suggested for the equivalent reaction in water.
New Syntheses of Demethylsuberosin, Xanthyletin, (±)-Decursinol, (+)-Marmesin, (−)-Nodakenetin, (±)-Decursin, and (±)-Prantschimgin
Authors: Steck Warren
Published: May 2006

The title compounds, natural coumarins or their racemic modifications, were synthesized via malonic acid condensations with appropriate salicylaldehydes. Oxidation of 2,4-dihydroxy-5-(3-methyl-2 butenyl)benzaldehyde with DDQ, peracid, and acid–peracid gave the aldehydes for xanthyletin, marmesin, and decursinol, respectively. Some 14C-labelled coumarins were prepared similarly. The n.m.r. spectral data for the products are presented.
Calcium(II) and Magnesium(II) Binding by L-Serine Orthophosphate in Aqueous Solutions
Authors: Childs C. W.
Published: May 2006

The dissociation of L-serine orthophosphate (H3L) and its complexation reactions with calcium(II) and magnesium(II) have been studied by potentiometric titration at 37 °C in the 0.15 mol l−1 potassium nitrate medium and (with the exception of calcium(II) complexation) in the 0.15 mol l−1 tetraethylammonium bromide medium. A least squares interpretation of the data has yielded dissociation constants for H3L and equilibrium constants for the formation of the 1:1 metal–ion complexes MH2L+, MHL, and ML−. In addition the dimeric species H5L2−, MH3L2−, and M2H2L2 are consistent with the data and equilibrium constants for their formation have been determined.
A Novel Synthesis of β-Hydroxyvaline
Authors: Berse Casimir , Bessette Pierre
Published: May 2006

The synthesis of β-hydroxyvaline from ethyl β,β-dimethylacrylate through 1,2-di(ethoxycarbonyl)-3,3-dimethylaziridine as intermediate shows a new way of preparation of this amino acid.
Effect of Pressure on the Rates of Reaction of Radiolysis Intermediates in Liquid n-Hexane
Authors: Jha Kamal N. , Freeman Gordon R.
Published: May 2006

The yield of hydrogen from pure hexane, G(H2) = 5.3 ± 0.2 was independent of pressure in the range 1 bar to 4.6 kbars. The G values of H2, HD, and D2 obtained from 11 mol% C6D14 in C6H14 were independent of pressure and were respectively, 4.85, 0.34, and 0.11. The electron and hydrogen atom scavenging efficiencies of carbon tetrachloride and hexadiene-1,3, and the hydrogen atom scavenging efficiency of hexene-1 were independent of pressure. The positive ion scavenging efficiencies of benzene and aniline increased with increasing pressure. The volume of activation for the hydrogen atom reaction with n-hexane is essentially the same as that for the reaction with hexene-1. The pressure dependence of the charge scavenging reactions has been interpreted in terms of the kinetics of spur processes. The treatment is consistent with the fact that the efficiency of the electron scavenging reactions is independent of pressure. The increased efficiency of positive ion reaction under pressure implies that the ratio of the diffusion coefficients of the radiolytic positive ion and electron, D+/D−, increases with increasing pressure.
Isocarbostyrils. I. Electrophilic Substitution Reactions
Authors: Horning D. E. , Lacasse G. , Muchowski J. M.
Published: May 2006

The electrophilic substitution of N-alkylated isocarbostyrils was examined in considerable detail. Bromination, acylation, nitration, and acid-catalyzed condensation with formaldehyde occurred exclusively at C-4 under relatively mild conditions. The acylation of isocarbostyrils has heretofore not been reported.The bromination of 2-methyl-5-nitroisocarbostyril in aqueous acetic acid gave 2-methyl-3,4-dihydro-3-hydroxy-4-bromo-5-nitroisocarbostyril (7) of unknown stereochemistry, as the sole product. When heated above its melting point, 7 lost the elements of water to give the "normal" product of bromination 8.In aqueous acetic acid, excess bromine was shown to convert isocarbostyrils to the corresponding 3,4-dihydro-3-hydroxy-4,4-dibromo derivatives whose structures were supported by spectral and degradative evidence.
Thermodynamic Analysis of the Hammett Equation, the Temperature Dependence of ρ, and the Isoequilibrium (Isokinetic) Relationship
Authors: Hepler Loren G.
Published: May 2006

Exact thermodynamic analysis of the Hammett equation has led to four differential equations relating δΔH0, δΔS0, δΔCp0, dρ/dT, and d2ρ/dT2. Similar equations can be obtained in terms of activation parameters ΔH≠, etc. For temperature independent δΔH0 and δΔS0 and therefore δΔCp0 = 0, two of these differential equations lead to ρ = ρ∞ [1–(β1/T)] and the familiar isoequilibrium (isokinetic) equation δΔH0 = β1δΔS0. The "isoequilibrium (isokinetic) temperature" represented here by β1 is a temperature independent constant of integration. For constant non-zero δΔCp0 we similarly obtain more complicated expressions for ρ and the "isoequilibrium (isokinetic) temperature." These findings are considered in relation to a model in which environmental contributions (due to solute–solvent interactions) to δΔH0 and δΔS0 are related by a parameter βc. The relationship between β1, and βc is established, and it is shown that in general β1 ≠ βc.
Infrared Spectra of Some Alkyl Platinum Compounds. Part II. Assignment of the CH Stretching Modes of a Methyl Group
Authors: Morrow B. A. , Beauchamp Y.
Published: May 2006

Several isotopically substituted triphenylphosphine stabilized dimethyl platinum compounds of the type (Ph3P)2PtMe2 where Me = CH3, CH2D, CD2H, and CD3 have been prepared and their infrared spectra in the CH and CD Stretching regions have been examined. The assignments of the stretching vibrations of the methyl group have been confirmed by means of an application of the Average Rule for isotopically substituted species. The possible application of the Average Rule as a general method for assigning CH stretching modes is discussed and it is suggested that the method could be used to confirm some recently proposed reassignments of the traditional Fox and Martin assignments. The method may also be used by surface chemists as a means of determining the number of hydrogen atoms in an adsorbed XHn species.
Reaction of Iodine Azide with Cyclopentenone and Cyclohexenone
Authors: McIntosh John M.
Published: May 2006

The addition of iodine azide to 2-cyclopentenone led to the formation of 2-iodo-2-cyclopentenone. A similar reaction with 2-cyclohexenone afforded the expected addition products in addition to 2-iodo-2-cyclohexenone.
Reaction of Diphenylcyclopropenethione with Heteroaromatic Nitrogen Compounds
Authors: Lown J. W. , Matsumoto K.
Published: May 2006

Diphenylcyclopropenethione reacts with a variety of heteroaromatic nitrogen compounds to give in excellent yields four types of products (a) 6,7-diphenyl-8-thionpyrazolo[1,2-a]pyridazine and -cinnolines, (b) azaindolizinthiols, (c) azaindolizine disulfides, and (d) 1-methoxy-1,2-diphenyl-3-thionpyrrolidino-[1,2-a]isoquinoline and similar structures. Proof of structure of products of type a rests on their independent synthesis by the action of phosphorus pentasulfide on the known oxo-analogs. Products of type b are converted readily into type c by air oxidation. In products of type d a molecule of solvent methanol is incorporated in the structures.
A Study of Steric Effects on Nitromethylene Acidity and the Mechanism of Epimerization in Partially Blocked Nitro Hexoses
Authors: Baer Hans H. , Rank Werner
Published: May 2006

The extent of nitronate formation in seven methyl 4,6-O-benzylidene-3-deoxy-3-nitrohexopyranosides and four methyl 4,6-O-benzylidene-2,3-dideoxy-3-nitrohexopyranosides in dilute potassium hydroxide solution was compared by means of u.v. spectroscopy. Considerable differences were found to exist in the nitromethylene acidities, and these were correlated with stereochemical features of the molecules. A facile manno → gluco epimerization occurring in this series was investigated. It was shown that, in alkaline alcoholic solution, the epimerization proceeds by an elimination–addition via an intermediate nitroalkene if the hydroxyl group at C-2 is acetylated. However, if the hydroxyl is free, the nitroalkene is not an intermediate and, in accord with the low nitromethylene acidity in this particular case, the mechanism is suggested to involve a reverse Henry reaction.
Solvent Effects in Free Radical Copolymerization
Authors: Chatterjee A. M. , Burns C. M.
Published: May 2006

Acrylamide and N-vinyl pyrrolidone were copolymerized at 60° in binary aqueous solutions containing 0, 5, 67, and 80% glycerol by weight. A marked increase in the reactivity of acrylamide relative to that of N-vinyl pyrrolidone was observed. This increase is interpreted in terms of the relative reactivity of monomer and polymeric radical in the reaction medium.
Enthalpies and Excess Enthalpies of Transfer of n-Alkylamine Hydrobromides from H2O to D2O at 25 °C
Authors: Desnoyers J. E. , Francescon R. , Picker P. , Jolicoeur C.
Published: May 2006

Differences in heats of solution and in heats of dilution of electrolytes in H2O and D2O were measured directly with a previously described cell-type differential microcalorimeter. In addition to NaCl and NaBr, most of the homologous salts RNH3Br were studied from R = methyl to R = n-octyl. The results of the two simple salts are in excellent agreement with the best literature values.The enthalpies of transfer at infinite dilution, ΔHtr0 (H2O → D2O), are mainly a measure of the structural ion–solvent interactions and of the exchange reaction[Formula: see text]Up to R = n-propyl, the relative apparent molal enthalpies of transfer, [Formula: see text], are negative, approximately zero for n-butyl and positive for the higher members. This gradual change in the excess enthalpies of transfer is interpreted in terms of the increasing importance of hydrophobic interactions between the cations. When association occurs through micelle formation (R = n-octyl), there is a rapid increase in [Formula: see text] which results from hydrophobic bonding.