bluuebunny/crossref_metadata_2025 huggingface dataset:
Preliminary investigation of an 8-quinolinol complex of uranium(VI)
Authors: Fleming J. E. , Lynton H.
Published: May 2006

The present work suggests that the chelate UO2(C9H6NO)2.C9H6NOH can be crystallized from chloroform as orange-red crystals which are monoclinic, space group P21with a = 14.98 Å (σ = 0.03 Å), b = 20.38 Å (σ = 0.05 Å), c = 14.75 Å (σ = 0.03 Å), and β = 115.32° (σ = 0.20°). It is believed that six molecules are in the unit cell: three sets of molecules in the general positions (2a). The uranium positions have been established and show the higher symmetry P21/m with four atoms in general positions and two atoms in the pseudo mirror planes. The molecular arrangement of 8-quinolinol molecules around the more general uranium atoms has been obtained from three-dimensional Fourier syntheses. This arrangement of 8-quinolinol molecules is essentially the same as found by Hall, Rae, and Waters in the adduct UO2(C9H6NO)2.C9H6NOH.CHCl3. The molecular arrangement around the two remaining uranium atoms has not been established because of false detail introduced by the pseudo-symmetry. This is enhanced by pronounced termination of series errors in the b-axis direction.
Radiolysis of methylcyclohexane. III. Pure vapor phase and effects of additives
Authors: Holtslander W. J. , Freeman G. R.
Published: May 2006

The radiolysis of methylcyclohexene (MCH) vapor was carried out under a variety of conditions. The G-values of the main products at 110°, extrapolated to zero dose, are hydrogen (5.2), methylcyclohexene isomers (2.0), ethylene (1.5), methane (1.3), propylene (0.8), and total dimer (0.3). Other products were also measured.The hydrogen yield was reduced to G = 3.1 by each of the additives, N2O, SF6, and CCL4, and to G = 1.6 by C2H4. Both DI and ND3 increased the total hydrogen yield above the value in pure MCH. In pure MCH approximately 50% of the ions (G(total ionization) = 4.4) resulted in hydrogen formation, whereas in the presence of DI or ND3, 75% of the ions are hydrogen precursors. Thus three different types of positive ions are distinguished in the system: G(M1+) = 2.1, G(M2+) = 1.3, and G(N+) = 1.0.The average ion lifetime with respect to neutralization was 10−3 s. The ion DI−was therefore stable with respect to decomposition to D + I− for a period greater than 10–3 s under the conditions of the experiments (~380 Torr MCH, 110°).The yield of methylcyclohexene isomers increased with increasing temperature and increased upon addition of ND3 or C2H4 to the radiolysis system. The dimer yield was also enhanced by the addition of ND3. This effect was explained by the occurrence of an ionic secondary reaction that destroys methylcyclohexene and (or) methylcyclohexyl radicals in pure MCH.Approximately 85% of the methane is produced by methyl radicals abstracting hydrogen atoms from MCH.
The Hg(3P1) photosensitized decomposition of ethylenimine and ethylenimine-d4
Authors: Klemm R. F.
Published: May 2006

Quantum yields as a function of reaction time and substrate pressure (20–200 Torr) have been obtained for the products H2, C2H4, NH3, N2, CH4, and C2H6 (their relative importance decreases in that order). The isotopic composition of the hydrogen from the decomposition of ethylenimine-d4 (El-d4) supports preferential hydrogen-atom detachment from nitrogen. Since addition of substantial amounts of C2H4 did not affect the yield of NH3, the implication of the NH (triplet) in the Hg sensitized decomposition of El is questioned. It is also proposed that the products investigated originate from the degradation of an excited El.
Spectroscopic study of the reaction of active nitrogen with some organometallic compounds
Authors: March R. E. , Schiff H. I.
Published: May 2006

Transfer of energy from constituents in active nitrogen to gaseous organometallic compounds leads to dissociation of the organometallic and excitation of CN and (or) metal atom. Organometallic compounds of aluminium, zinc, and boron were used in this investigation. The observed emission lines from metal atoms and highly vibrationally excited CN correspond to an initial energy transfer in excess of 200 kcal/mole. The possible role of N2(5Σg+) molecules as excitors is discussed in the light of the results obtained.
Spectral evidence for the structure of three flavanotropolones related to theaflavin, an orange-red pigment of black tea
Authors: Takino Y. , Ferretti A. , Flanagan V. , Gianturco M. A. , Vogel M.
Published: May 2006

Conclusive spectral evidence for the structure of categallin (V), pyrogallin (VI), and erycetin (VIII), three flavanotropolones related to theaflavin (I) and purpurogallin (IX), is presented. The synthetic, chromatographic, and spectroscopic data for four simpler hydroxybenzotropolones are also recorded and discussed.
Solvent effects in ultraviolet spectral studies of hydrogen bonding between phenol and N,N-dimethylacetamide
Authors: Takahashi F. , Karoly W. J. , Greenshields J. B. , Li N. C.
Published: May 2006

Ultraviolet spectral studies of hydrogen bonding between phenol and N,N-dimethylacetamide (DMA) in several media are reported. The equilibrium constant for the formation of the phenol–DMA complex is strongly solvent dependent, varying from 295 1/mole in cyclohexane to 130 in CCl4 and 16 in CHCl3, all at 28°. The greatly reduced value in CHCl3 indicates that the measured equilibrium constant is only an apparent one which does not take into account the decrease in free DMA concentration resulting from hydrogen-bonded complex formation with the solvent acting as hydrogen donor. In CCl4/CHCl3 mixed solvent, in the range of [chloroform] = 0 to 1.227 M, the measured equilibrium constant, K′, varies linearly with K′ [chloroform]. The slope of the line corresponds to the equilibrium constant for the formation of the hydrogen-bonded complex between CHCl3 and DMA in CCl4. The value, 0.9 1/mole, agrees with that obtained from a proton magnetic resonance method. The agreement is particularly noteworthy when we consider that the concentrations of phenol used in the proton magnetic resonance and ultraviolet spectral methods differ by a factor of 200, which leads definitely to the conclusion that the hydrogen-bonded CHCl3–DMA complex formed is 1:1. In cyclohexane/CHCl3 mixed solvent, similar results are obtained.
Radiation chemical data in water using nitrous oxide
Authors: Head D. A. , Walker D. C.
Published: May 2006

By using small doses and very low dose rates, it is shown that in the γ-irradiation of water ~ 8 × 10−5M nitrous oxide completely scavenges eaq− in the absence of other additives and gives a yield G(eaq−) = 2.45 ± 0.1. When used at concentrations of ~ 15 mM, N2O scavenges a second species having a yield G = 0.65 ± 0.1, which can probably be attributed to a hydrated hydrogen atom species resulting from the reaction of eaq– with H3O+ within the spur. Previous studies on the competition between N2O and Haq+ for eaq− have been conducted at concentrations of N2O much too high for simple competition to be valid, which probably accounts for the erratic results obtained. This paper reports on the competition studied at ~ 10−4 M. The results cannot be interpreted either in terms of a simple competition or by one, or both, of the immediate products reacting with either of the additives. The data can only be rationalized by assuming that in acid solution N2O is converted to a species, tentatively suggested to be H2N2O2, which reacts with eaq− 5 times more slowly than does N2Oaq at pH 7.
Hydrolysis of α-bromoisobutyrate ion in water
Authors: Hendy B. N. , Redmond W. A. , Robertson R. E.
Published: May 2006

The temperature dependence of the rate of hydrolysis of α-bromoisobutyrate ion in water was determined over a temperature range 9–37 °C. From these data corresponding values of ΔH≠, ΔS≠, and ΔCP≠ have been derived. The implication of these terms, together with corresponding data for hydrolysis in D2O and for the secondary deuterium isotope effect from the hydrolysis of (CD3)2CBrCOO−, provide a basis for reexamining the detailed mechanism with particular reference to accompanying solvent reorganization.
Rearrangement studies with 14C. XXIX. The deoxidation of 2-phenyl-1-14C-ethanol
Authors: Lee C. C. , Hahn Bo-Sup
Published: May 2006

The product (styrene) derived from the deoxidation of 2-phenyl-1-14C-ethanol showed 22–26% rearrangement of the 14C label from C-1 to C-2. The extent of this rearrangement is quite close to the values reported for the analogous rearrangement in the deamination of 2-phenyl-l-14C-ethylamine, thus giving further support to the suggested similarity between deoxidation and deamination reactions. The 2-phenylethanol recovered from the deoxidation reaction mixture also showed 3–5% rearrangement of the 14C label from C-l to C-2. This constitutes the first observation of the formation of a rearranged alcohol in a deoxidation reaction. Other mechanistic implications of the results are discussed.
Intramolecular hydrogen bonds in ethylenediamines and otheraliphatic diamines
Authors: Krueger P. J.
Published: May 2006

The fundamental NH stretching bands of 22 aliphatic diamines have been investigated in dilute C2Cl4 solution.N,N′-Dimethyl-1,3-propanediamine and N,N′-dimethyl- and N,N,N′-trimethyl-ethylenediamine exist predominantly in an intramolecularly hydrogen bonded conformation. Such bonding also exists in N-methyl- and N,N -dimethyl-ethylenediamine, in N-methyl- and N,N-dimethyl-1,3-propanediamine, and in amines of the type H2N(CH2-CH2NH)xCH2CH2NH2. For all of the diamines investigated, intramolecular NH···N bonding disappears sharply when the intervening methylene chain length exceeds three units. Integrated band intensity measurements for primary aliphatic diamines H2N(CH2)nNH2 over the range n = 2–12 suggest that intramolecular hydrogen bonds may also play an important role in the conformation of ethylenediamine and 1,3-diaminopropane.
The valence tautomer of methyl-7-oxa-bicyclo[2.2.1]hepta-2,5-diene-2,3-dicarboxylate and its dimer
Authors: Deslongchamps P. , Kallos J.
Published: May 2006

Irradiation of diester I gave the photoisomer II. This quadricyclic compound (II) dimerized on standing. A structure for the dimer is proposed on the basis of its spectral properties.
Acylation of guanidines and guanylhydrazones
Authors: Prasad Raj Nandan , McKay A. F.
Published: May 2006

A number of acyl derivatives of guanidines and guanylhydrazones have been synthesized and evaluated for their antibacterial activity. The synthesis of some of the guanidines and guanylhydrazones is discussed.
Disproportionation and combination reactions of simple alkyl radicals: methyl, ethyl, n-propyl, and isopropyl
Authors: Terry J. O. , Futrell J. H.
Published: May 2006

Rates of the possible cross-disproportionation reactions of these radicals relative to their rates of cross-combination, have been measured and are compared with auto-disproportionation-to-combination ratios which were also determined for these radicals. Selected asymmetric azo alkanes RNNR′ and mixtures of symmetric azo alkanes RNNR were used as sources of the desired free radicals. Photolysis under relatively high intensity conditions (ca. 1018 quanta/cm2 s) at room temperature generated the radicals in sufficiently high concentration that competing reactions of abstraction and condensation were negligible. Both the alkene and alkane products of disproportionation reactions were measured to ensure the completeness of the mechanism invoked and to increase the accuracy of the results. Δ(Me, Et) = 0.036 ± 0.003, Δ(Me, Prn) = 0.058 ± 0.004, Δ(Me, Prs) = 0.163 ± 0.005, Δ(Et, Prn) = 0.065 ± 0.005, Δ(Et, Prs) = 0.18 ± 0.008, Δ(Prn, Et) = 0.057 ± 0.005, Δ(Prs, Et) = 0.12 ± 0.01, and Δ(Prn, Prs) = 0.41 ± 0.02 were deduced from the data, where Δ(A, B) refers to the ratio of disproportionation producing the alkane product derived from A to the combination of A with B.
An evaluation of mathematical functions to fit infrared band envelopes
Authors: Pitha J. , Jones R. Norman
Published: May 2006

Simulated infrared absorption bands of condensed phase systems have been fitted with simple analytical functions by least-squares procedures. The bands were of Cauchy (Lorentz) contour and were modified to conform with the finite spectral slit distortion of the spectrophotometer. Cauchy, Cauchy–Gauss product, and Cauchy–Gauss sum functions were used in the fitting procedures using transmittance ordinates. The fits achieved were compared and the dependence of the optimized indices on the band distortion and data range were analyzed. Some preference for the Cauchy–Gauss sum function is indicated.
Shape of the cellodextrins in aqueous solution at 25 °C
Authors: Ihnat M. , Goring D. A. I.
Published: May 2006

Diffusion coefficients and intrinsic viscosities of the cellodextrins, cellobiose to cellohexaose, were measured in aqueous solution at 25 °C. Axial ratios of the oligomers were computed by the Stokes–Einstein diffusion equation modified for non-spherical particles by Perrin's theory, and by the Einstein–Simha viscosity equation. The hydrodynamically calculated axial ratios were equal to the corresponding axial ratios determined from fully extended Stuart–Briegleb models after allowances were made for hydration. Thus the cellodextrins appear to be rodlike and give no indication of pronounced flexibility or folding in aqueous solution at 25 °C.
Flash photolysis under non-isothermal conditions
Authors: Burns George
Published: May 2006

The temperature rise which accompanies every flash photolytic reaction interferes with, and often makes impractical, measurements of the reaction rate constants. This difficulty may be partly overcome if the whole reaction vessel is uniformly irradiated by both the photolytic and the analyzing flash lamps.A flash photolysis apparatus with these characteristics was used to study bromine atom recombination. A 10 to 15 fold gain in atomic concentration, which corresponds to a 100 to 225 fold increase in three-body recombination rate, compared with the work of previous authors, was achieved with this apparatus. The reaction rate constants were determined from the changes in absorption of Br2 at either 4 035 Å or at 4 980 Å. The recombination rate constant of bromine in an excess of helium at 90 ± 20 °C was found to be equal to (0.8 ± 0.3)109 l2 mole−2 s−1 (measured at 4 980 Å) and (0.5 ± 0.1)109 l2 mole−2 s−1 (measured at 4 035 Å). The results suggest that the technique herein described can yield meaningful data, even though the reaction was accompanied by a 105 °C temperature rise. There was little heat exchanged between the reacting gas and the walls of the reaction vessel. Consequently the reaction vessel behaved as an effective calorimeter throughout the reaction.
Reactions of tetrabutylammonium halides with boron trifluoride and phosphorus pentafluoride
Authors: Brownstein S.
Published: May 2006

Tetrabutylammonium halides react with one or more molecules of boron trifluoride or phosphorus pentafluoride at low temperature in dilute methylene chloride solution. Rapid, frequently concentration dependent equilibria occur in the nonideal solutions. The products isolated upon evaporation of solvent may not be those present in the dilute solutions. Usually a disproportionation occurs to yield BF4− or PF6−. With the exception of B2F7−, no complex ions involving fluorine bridging were found in solution or in the reaction products.
Reaction between alkali metal ferrocyanides and persulfates in aqueous solution
Authors: Chlebek R. W. , Lister M. W.
Published: May 2006

The rates of the reaction of ferrocyanide and persulfate ions, in the presence of various concentrations of different alkali metal cations, have been measured at various temperatures and ionic strengths. The results are interpreted in terms of ion pairs and support the view that the actual reacting species are MFe(CN)6−3 and MS2O8−, where M is an alkali metal. This is similar to the situation found earlier for potassium salts of these ions. The rate constants obtained on this assumption increase gradually from lithium to cesium. Values are also obtained for the apparent activation energies of these reactions.
The inhibited autoxidation of styrene. Part VI. The relative efficiencies and the kinetics for inhibition by N-aryl anilines and N-alkyl anilines
Authors: Brownlie I. T. , Ingold K. U.
Published: May 2006

The kinetics and deuterium isotope effects for the N-aryl aniline and N-alkyl aniline inhibited autoxidation of styrene indicate that the rate-controlling step for inhibition involves abstraction of the amino hydrogen by a peroxy radical. The rate constants for this reaction have been correlated by means of the Hammett equation with the σ+ constants of the substituents for diphenylamines (ρ = −0.89) and N-methylanilines (ρ = −1.6). A numerical difference involving a factor of two between the simple kinetic expression applicable to most aromatic amine inhibitors and the expression applicable to most phenols and p-phenylenediamines is suggested. The important role played by the substrate in studies of inhibitor action is emphasized.
Experiments on congruent concentrations in binary liquid mixtures
Authors: Campbell A. N. , Kartzmark E. M.
Published: May 2006

The coexistence curves L1 [Formula: see text] L2 of the following systems have been investigated: (1) aniline–hexane; (2) methanol–cyclohexane; (3) methanol – carbon bisulfide; (4) acetic anhydride – cyclohexane; (5) acetic anhydride – carbon bisulfide; (6) triethylamine–water. Instead of using the usual method of Alexejew, which has disadvantages stated in the text, we have preferred the direct analysis of equilibrium phases at constant temperature.
A linear correlation of aromatic substituent effects with geminal coupling constants
Authors: Franck Richard W. , Auerbach Joseph
Published: May 2006

A linear correlation of the geminal coupling constants of benzylic protons with the Hammett σ constants has been observed. The proton–proton coupling was made observable by preparing the tetrahydropyranyl ethers of benzyl alcohols. The introduction of the asymmetric center caused the benzyl protons to become non-equivalent. The observed correlation serves as an additional confirmation of the Pople and Bothner-By theory of geminal coupling.
Cyclic organophosphorus compounds. II. Some sterically hindered cyclic hypophosphate systems and related compounds
Authors: Stec W. , Zwierzak A.
Published: May 2006

The synthesis of three new cyclic hypophosphate systems from 2,2-dimethylpropane-1,3-diol is described. Evidence concerning the presence of the P—P bond in the cyclic hypophosphate and cyclic dithiohypophosphate was obtained by chlorinolysis.In addition, the reactions between 2-ethoxy-5,5-dimethyl-1,3,2-dioxaphosphorinan and 2-chloro-2-oxo-5,5-dimethyl-1,3,2-dioxaphosphorinan and between 2-hydroxy-5,5-dimethyl-1,3,2-dioxaphosphorinan and 2-chloro-5,5-dimethyl-1,3,2-dioxaphorinan are discussed as possible routes to cyclic hypophosphates.Several characteristic features of the infrared spectra of cyclic hypophosphate systems, related compounds, and their acyclic analogues are indicated.
Conformational studies of α-substituted ketones by nuclear magnetic resonance
Authors: Gough T. E. , Lin W. S. , Woolford R. G.
Published: May 2006

The nuclear magnetic resonance spectra are reported for a series of α-substituted 3-pentanones. Magnetically nonequivalent methylene hydrogens are observed whenever the substituent group is diamagnetically anisotropic. The results are discussed in terms of the possible conformations of the molecules; the most stable conformations are those with the C=O bond essentially eclipsed by the terminal methyl groups.
Aminimides. I. A general synthesis of aminimides from acyl hydrazides and their pyrolysis
Authors: McKillip William J. , Clemens Lawrence M. , Haugland Richard
Published: May 2006

Acyclic, alicyclic, and aromatic bis-trimethylaminimides and a keto-substituted trimethylaminimide have been synthesized by a stepwise route of general applicability. Pyrolysis of the aliphatic aminimides resulted in a rearrangement to trimethylamine and isocyanate. The keto-isocyanate herein reported was synthesized in a convenient four-step sequence from dimethyl ketene dimer in a good yield, and provides an attractive new route to this type of difunctional compound. Pyrolysis of the bis-aminimides in the presence of polyhydroxylic materials gave polyurethanes.
The ionization gauge as a species-discriminating detector for molecular beams
Authors: Yealland R. Michael , LeRoy Rodney L. , Deckers Jacques M.
Published: May 2006

A method is described by which an ion gauge, used as a molecular-beam flux detector, can discriminate between signals produced by two gases, provided they have a mass ratio of at least 2 and are present in comparable amounts. The method employs a mechanically chopped beam with narrow band phase-sensitive detection. Separation of two signals is possible because of the different rates of effusion of the two gases out of the gauge. Because of this the phase of the a.c. signal extracted by the lock-in amplifier depends on the beam composition. A theoretical analysis of the phenomena is presented and is compared with experimental data. Limitations of the method are also considered.
Molar excess enthalpies of binary n-alcohol systems at 25 °C
Authors: Pope A. E. , Pflug H. D. , Dacre B. , Benson G. C.
Published: May 2006

The heats of mixing of the 11 binary n-alcohol systems containing either butanol or octanol and formed from the set methanol, ethanol, propanol, butanol, hexanol, octanol, and decanol were measured in a continuous dilution calorimeter at 25 °C. The applicability of Brønsted's principle of congruence to the data was investigated.
Isomer ratios for the 88Sr(p,xn) and 88Sr(p,p3n) reactions
Authors: Sachdev D. R. , Yaffe L.
Published: May 2006

Isomeric cross-section ratios for nuclides formed from (p,2n), (p,3n), (p,4n), and (p,p3n) reactions on 88Sr are presented. The experimental results for the 88Sr(p,2n)87Ym,g reaction are compared with statistical-model calculations wherein spin-density parameter values were obtained from various theoretical formalisms. The parameters required to match the calculated and experimental values are in good agreement with those obtained by Vandenbosch et al.
Detection of trapped electrons in organic glasses after gamma irradiation at 4.2 °K by electron spin resonance spectroscopy
Authors: Smith D. R. , Pieroni J. J.
Published: May 2006

Several organic glasses which are known to form trapped electrons when gamma irradiated at 77 °K have been irradiated at 4.2 °K and examined by electron spin resonance (e.s.r.) at the same temperature. In each case an absorption is observed which is probably due to trapped electrons. In three cases, the yield of trapped electrons at 4.2 °K seems to be as great as at 77 °K. In one case, a glassy alkane, the yield is enhanced at 4.2 °K. Trapped electrons in ethanol give a narrower e.s.r. line at 4.2 °K than at 77 °K, suggesting less orientation in the solvent cage.Trapped hydrogen atoms are not detected after irradiation at 4.2 °K. Contrary to prediction, hydrogen atoms are also not detected after post-irradiation photolysis of the trapped electrons.The results suggest that electron traps exist prior to irradiation and that molecular orientation via electronic dipole interaction is not a necessary condition for electron trapping. The results do not distinguish between trapping in solvent defects or trapping via electron-induced polarization of molecular orbitals.
Comparative formation constants for complexes of copper, nickel, and silver with some substituted pyridines
Authors: Sun M. S. , Brewer D. G.
Published: May 2006

Formation constants for metal complexes of Cu(II), Ni(II), and Ag(I) with some substituted pyridine ligands were determined in a nitrate salt solution of the ligand (0.5 F KNO3 + 0.1 F HL) at 25 °C by pH measurement. The linear relationship shown by a logarithmic plot of the formation constant versus the basicity of the ligands characterizes qualitatively the dΠ → pπ-bonding capacity for each metal ion. The 2-substituents, such as —CH3 and —NH2, on these pyridine ligands have a very profound steric effect upon the stabilities of Cu(II) and Ni(II) complexes, but have no such effect upon that of Ag(I) complexes. An explanation is given which may be useful in selecting analytical reagents.
Free-radical-catalyzed isomerization of isocyanides
Authors: Shaw D. H. , Pritchard H. O.
Published: May 2006

The isomerization of methyl isocyanide and of ethyl isocyanide, catalyzed by methyl radicals produced in the thermal decomposition of di-tert-butyl peroxide, has been studied in the gas phase at temperatures near 100 °C. The Arrhenius parameters for the reaction CH3NC + CH3 → CH3 + CH3CN are E = 7.8 ± 0.3 kcal/mole and A = 1012.25 mole−1 cc s−1. It is proposed that the reaction proceeds by addition of the incoming radical to the divalent carbon atom of the isocyanide group, followed by expulsion of the radical originally attached to the N atom. The thermochemistry of addition to the divalent carbon atom is discussed in an Appendix.
Thermochemistry of the methoxymethyl radical
Authors: Loucks L. F. , Laidler K. J.
Published: May 2006

A kinetic study has been made of the pyrolysis of 1,2-dimethoxyethane, CH3OCH2CH2OCH3, using toluene as a radical scavenger. The initial step involves the C—C split, and there are no chains; the activation energy of 71.3 kcal/mole thus corresponds to the dissociation energy of the C—C bond. The heat of formation of CH3OCH2CH2OCH3 has been found to be −81.4 kcal/mole, and these values lead to −5.0 for the heat of formation of the CH3OCH2 radical and 91.1 for the dissociation energy of CH3OCH2—H.Support for these values is provided by the results of a similar study with chloromethyl methyl ether, CH3OCH2C1, for which the C—Cl bond is ruptured in the initial step. Activation energies of 69.3 and 69.9 kcal/mole were found with toluene and propylene as scavengers. With the use of appearance-potential data these values lead to D(CH3OCH2—H) = 92.9 and ΔHf0(CH3OCH2) = −3.2 kcal/mole, with, however, a wider margin of error than for the results with CH3OCH2CH2OCH3.
Thermal decomposition of the ethyl radical
Authors: Loucks L. F. , Laidler K. J.
Published: May 2006

The kinetics of the thermal decomposition of the ethyl radical to give an ethylene molecule and a hydrogen atom were studied over the pressure range 4 to 650 mm Hg and the temperature range 400 to 500 °C; the mercury-photosensitized decomposition of ethane was used to generate the ethyl radical. The unimolecular decomposition of the ethyl radical was found to be pressure dependent over the entire range of pressures studied, with the order of reaction varying from 1.6 for the lowest pressures to 1.4 at the highest pressures. The extrapolated high-pressure and low-pressure rate constants for the decomposition of the ethyl radical are given by

[Formula: see text]

[Formula: see text]A best fit of the Kassel equation to the observed pressure dependence shows that s = 8 for this reaction. The results lead to a value of 98 1 kcal/mole for the bond dissociation energy D(C2H5—H). The heat of formation of the ethyl radical was calculated to be 30.0 and 26.2 kcal/mole for 0 °K and 25 °C respectively.
Nuclear magnetic resonance studies. XIV. Conformational equilibria of α-halocyclohexanones
Authors: Pan Yuh-Hsu , Stothers J. B.
Published: May 2006

The conformational equilibria of α-fluoro-, α-chloro-, and α-bromo-cyclohexanone have been examined by proton spectroscopy in cyclohexane, carbon tetrachloride, benzene, chloroform, p-dioxane, and acetonitrile solutions over a range of concentrations. The cis- and trans-4-t-butyl derivatives were used as reference compounds for the two chair conformations. Equilibrium constants were estimated from the α-proton spectral data in two ways and compared with the results obtained by a variety of methods. Consistently good agreement was found between our results and those available from dipole moment measurements. This study is the most extensive investigation of the α-halocyclohexanone equilibria to date. Calculations using simple classical models for steric, electrostatic, and induced dipolar interactions were found to predict the observed trends. The solvent effects on the axial and equatorial α-proton shieldings in the "fixed" systems are discussed in terms of solute–solute and (or) solute–solvent interactions, and evidence for reaction field contributions is presented.
Synthesis of 1-aryl(and 1-aralkyl)-β-carbolines
Authors: Ho Beng T. , McIsaac William M. , Tansey L. Wayne , Walker K. E.
Published: May 2006

Some aromatic 1-aryl(and 1-aralkyl)-β-carbolines were prepared from their tetrahydro analogues by dehydrogenation over palladium on charcoal either in a Parr bomb or in refluxing toluene. The bomb reaction appears to be a better procedure for the preparations of aromatic β-carbolines with bulky C-1 substituents such as the naphthyl group. 1-(1-Naphthyl)- and 1-(2-naphthyl)-tetrahydro-β-carbolines were obtained by the cyclization of the Schiff bases N-(l-naphthylmethylene)- and N-(2-naphthylmethylene)-tryptamines, respectively. Other tetrahydro-β-carbolines with smaller C-1 substituents were prepared by the condensation of tryptamine with the appropriate aldehydes.
5-Nitro-6-substituted-2-norbornenes: determination of Diels-Alder isomer ratios from nuclear magnetic resonance spectra
Authors: Noland Wayland E. , Langager Bruce A. , Manthey Joseph W. , Zacchei Anthony G. , Petrak Darryl L. , Eian Gilbert L.
Published: May 2006

The nuclear magnetic resonance spectra of representative 5-nitro-6-substituted-2-norbornenes (II–VII) are described. From the spectra, ratios of the two possible endo–exo trans stereoisomers derived from the Diels–Alder reaction of cyclopentadiene with the appropriate trans nitroölefin are estimated as shown in Table II. For all cases, there was predominance (3:1 to 9:1) of the 5-endo-nitro trans stereoisomer. The synthesis of the 6-(p-nitrophenyl) (V), 6-(2-furyl) (VI), and 6-(2-thienyl) (VII) derivatives is reported and the 6-ethyl derivative (III) has been characterized
Synthesis and polymerization of m-trimethylsilylphenylalanine N- carboxyanhydride
Authors: Zilkha Albert , Friedman Gad , Gertner David
Published: May 2006

m-Trimethylsilylphenylalanine was prepared by the malonic ester synthesis. The kinetics of the polymerization of its N-carboxyanhydride was investigated in dioxane and in dimethyl sulfoxide, with n-hexylamine as initiator, and compared with the polymerization of the para isomer. The polymerization proceeded in three successive stages. In dioxane the para isomer polymerized faster than the meta isomer, but in dimethyl sulfoxide the opposite was true. It is supposed that the difference in the solubility of the polymers, leading to heterogeneity of the reaction medium, is the main cause for the difference in the rates.
Combination and overtone bands of ammonia adsorbed on silica
Authors: Cant N. W. , Little L. H.
Published: May 2006

The ν2 symmetrical deformation vibration for ammonia adsorbed on silica cannot be observed directly, owing to strong absorption arising from the adsorbent. It is possible, however, to calculate a value for this vibrational frequency based on combination bands for the adsorbed ammonia, which occur in regions remote from strong absorption by the silica. The frequency of the ν2 mode reflects the strength of bonding in both the adsorbed state and in metal–ammine complexes.
Aqueous nonelectrolyte solutions. Part V. Water – ethylene oxide ice freezing points, molar volumes, and proton magnetic resonance chemical shifts
Authors: Glew D. N. , Mak H. D. , Rath N. S.
Published: May 2006

Densities at 10 °C and proton magnetic resonance (p.m.r.) chemical shifts at 0 °C have been measured for aqueous ethylene oxide over the whole solution composition range. Ice freezing points have been determined for solutions containing up to 2 mole % ethylene oxide in water and in deuterium oxide. The deuterium oxide freezing point is 3.809 ± 0.003 °C and its freezing enthalpy is −1510 ± 8 cal. The freezing point measurements show water and deuterium oxide having unexpected negative deviations from Raoult's law. A maximum thermodynamic stabilization of water is found for solutions containing 4 mole % ethylene oxide. Partial molar volume evaluation shows a water volume maximum at 3.2 mole % ethylene oxide and a minimum at about 89%. Proton magnetic resonance measurements indicate weak H-bonding of water to ethylene oxide involving only one lone pair per ethylene oxide molecule. An abnormal shoulder in the direction of lower magnetic field for the water chemical shift is found, with the anomaly maximum at 4 to 6 mole % ethylene oxide.Correlating with the 20 and 24 water molecules encaging ethylene oxide in its clathrate hydrate, these new solution measurements show that when 20 to 30 water molecules are associated with each ethylene oxide at lower temperature, the water solvent exhibits a free energy minimum, a volume maximum, and an anomalous increase of water H-bond strength. At these compositions each ethylene oxide molecule is apparently surrounded by its own H-bonded water coordination shell to which it is weakly H bonded.
Ion lifetimes in irradiated gaseous HCl
Authors: Armstrong D. A. , Back R. A.
Published: May 2006

An intermittent-field method has been used to measure ion lifetimes in gaseous HCl during irradiation by gamma rays under conditions of pressure, dose rate, and vessel geometry similar to those employed in radiolysis studies. At 23 °C, with HCl pressures from 119 to 660 Torr and dose rates from 5.5 to 86 × 1010 eV cc−1 s−1, the ion half-life ranged from 6 to 30 ms. The dependence on dose rate and pressure strongly indicated that ion neutralization occurred almost entirely in the gas phase. Values of α, the gas-phase combination coefficient, were calculated; at pressures above 246 Torr the value was constant and equal to 3.1 ± 0.3 × 10−6 cc ions−1 s−1. The addition of SF6 had little effect on α, while reducing the temperature to −79 °C increased α to 5.1 × 10−6.
Radiolysis of gaseous isobutylene by 60Co γ rays. I. Decomposition products
Authors: Collin Guy J. , Herman Jan A.
Published: May 2006

The radiolysis of gaseous isobutylene yields the following products: iso-C4H10, H2, propyne, allene, C3H6, C2H2, C2H4, iso-C5H12, C3H8, C2H6, neo-C5H12, and a polymer. The radiochemical yields decrease with pressure, except for the yield of the polymer. Addition of NO decreases only the yields of iso-C4H10, CH4, C3H8, and C2H6, showing that at least partly these products are formed in radical reactions. A mechanism is proposed accounting for the formation of radiolysis products.
Reactions of thermal energy ions. VI. Hydrogen-transfer ion–molecule reactions involving polar molecules
Authors: Gupta S. K. , Jones E. G. , Harrison A. G. , Myher J. J.
Published: May 2006

The rate constants for formation of the protonated molecule by ion–molecule reactions in CH3OH, (CH3)2O, and CH4 have been studied both at thermal energies and at 3.4 eV ion exit energy with a new mass spectrometer described in the present work. The rate constants are found to be approximately a factor of two greater than previously measured and it is concluded that an error in pressure measurement was made in the earlier work. Revised rate constants are presented for a number of systems studied previously. The results are compared with predictions of the collision theory modified in this paper to include the effect of ion-dipole interactions.
Correlations of proton coupling constants in mono- and di-substituted ethylenes with the inverse of substituent electronegativities. A reconsideration of previous correlations
Authors: Schaefer T. , Hutton H. M.
Published: May 2006

It is shown that in mono- and di-substituted ethylenes the cis, trans, and geminal proton–proton coupling constants correlate with the inverse of the sum of the substituent electronegativities (one of the substituents may be hydrogen). Previous correlations indicated a direct negative proportionality between the two parameters. This was due to the restricted range of electronegativities over which the correlations were made. There appear to be no strong theoretical objections to the inverse proportionality between coupling constants and substituent electronegativities discussed in this paper.
Coordination complexes of gallium(III) and indium(III) halides. II. Far-infrared spectra of gallium(III) halide complexes with triarylphosphines
Authors: Carty Arthur J.
Published: May 2006

Infrared spectra of some triarylphosphine and diphosphine complexes of gallium (III) chloride, bromide, and iodide have been recorded in the range 600–200 cm−1 and assignments of gallium–halogen stretching vibrations made. The number and frequencies of the ν (Ga–X) vibrations are consistent with monomeric structures for the triarylphosphine complexes in the solid state. Possible structures for the diphosphine complexes are discussed.
Cyclohexane compounds. VII. Nucleophilic scission of the stereoisomeric 3-methoxycyclohexene oxides
Authors: Bannard R. A. B. , Casselman A. A. , Langstaff E. J. , Moir R. Y.
Published: May 2006

The mode of scission of cis- and trans-3-methoxycyclohexene oxides by hydrogen chloride, hydrogen bromide, ammonia, acetic acid, and methanol (under both acidic and alkaline conditions) has been examined using vapor-phase chromatography to detect and isolate minor isomers. Approximately 10% of the product from opening of the trans oxide is formed by attack at position-2 with each of these nucleophiles, whereas opening of the cis oxide proceeds exclusively by attack at position-1. The results are interpreted as reflecting very similar transition states for all of these reactions, with differences in product distributions for the two oxides being governed by the inductive effect of the methoxyl group and by steric factors in the corresponding transition states.
Thiohydantoins. VI. Hydrolysis of 1-acyl-2-thiohydantoins: reported anomalies
Authors: Edward J. T. , Liu J. K.
Published: May 2006

Two reports in which it was claimed that the 1-acyl group of a 1-acyl-2-thiohydantoin was not rapidly removed by dilute acid or alkali were investigated and found erroneous.
The effect of tetra-n-butylammonium salts on the nuclear magnetic resonance of nitrobenzene
Authors: Hyne J. B. , Fabris A. R.
Published: May 2006

Tetra-n-butylammonium salts effect the nuclear magnetic resonance response of the para and meta protons of nitrobenzene to a greater extent than that of the ortho protons in solutions in carbon tetra chloride. It is suggested that this effect may be due to a specific interaction between the salt, in ion-pair form, and the aromatic ring of nitrobenzene.
Theory of nucleation in solid state reactions
Authors: Allnatt A. R. , Jacobs P. W. M.
Published: May 2006

The theory of nucleation in solid state reactions is formulated in a general way and a solution to the problem of multi-step nucleation obtained. Two special cases of the general formulation are considered: the second of these corresponds to Bagdassarian's approximate model and some corrections to his treatment are pointed out. A new equation describing the kinetics of a solid state reaction, which involves multi-step nucleation followed by a constant and isotropic rate of growth, is derived. This equation is termed the generalized Avrami equation since it removes the restriction, in Avrami's treatment, of a single-step nucleation process. Erofeev's analysis of the problem is shown to be valid only in the limit of short times: the generalized Avrami equation reduces to Erofeev's equation in this limit.
Enthalpy and entropy of activation for benzyl chloride solvolysis in various alcohol–water solvent mixtures
Authors: Golinkin H. S. , Hyne J. B.
Published: May 2006

The first order rate constants for the solvolysis of benzyl chloride in a series of mixtures of methyl, ethyl, i-propyl, and t-butyl alcohols with water are reported at 40.05 and 60.50 °C. The ΔH* and ΔS* values are calculated using these rate constants and those previously reported at 50.25 °C (1, 2). The dependence of these parameters on solvent composition is discussed.
Catalytic hydrogenation of allene
Authors: Mann R. S. , To D. E.
Published: May 2006

The reaction between allene and hydrogen over pumice-supported metals of the eighth group has been investigated in a constant volume reactor for a wide range of temperature and reactant ratios. The shape of the pressure–time curves were found to be dependent upon the reactant ratios and their order of admission. The reaction over nickel–pumice is principally a selective formation of propylene with small yields of propane and reduced polymers of allene. The orders of hydrogenation reaction are first, or slightly higher, and zero with respect to hydrogen and allene respectively. The apparent activation energies for Pd, Pt, Co, Fe, Ni, Rh, Ir, Ru, and Os are 13, 17.4, 10.8, 9.4, 7.8, 9.6, 5.3, 3.0, and 4.6 kcal/mole respectively. The catalytic activities of the metals are in the sequence[Formula: see text]While selectivity was found to decrease with increasing initial hydrogen pressures, it increased with increasing temperatures.
Primary process in the photolysis of hexafluoroacetone in the presence of mercury vapor
Authors: Boyd R. K. , Carter G. B. , Kutschke K. O.
Published: May 2006

Studies have been made of the variation with ketone pressure of the quantum yield for the decomposition of hexafluoroacetone, excited by 3130 Å, at 25 and 78 °C, and of the relative yield of the total emission at several temperatures. These are described in considerable detail with a view to discerning possible sources of systematic error. No large systematic error could be identified except that of decreased yields caused by deactivation by mercury vapor. The decomposition data support the weak collision mechanism for vibrational relaxation in the excited singlet state unless an as yet unknown source of large systematic error can be identified.A description is offered of the path of the decomposition in terms of simplified diatomic representations of the nπ* singlet and triplet states and of a repulsive state arising from the radicals CF3 and CF3CO in their ground electronic states. On the basis of that description an activation energy ≥ 11 kcal mole−1, derived from the combined decomposition and emission data, is to be ascribed to the first-order decomposition of triplet state molecules in vibrational equilibrium with their surroundings.
Preparation of some organotin compounds containing methylthio, phenylthio, and pentafluoro-phenylthio groups
Authors: Peach M. E.
Published: May 2006

The new compounds n-Bu3SnSR, n-Bu2Sn(SR)2, where R = Me, Ph, or C6F5, and Ph3SnSC6F5 have been prepared and characterized. The fracture of the Sn—S bond with iodine has been examined and affords a quantitative method for analysis of compounds containing a Sn—S bond. The 1H and 19F n.m.r. have been studied; frequencies characteristic of the C6F5S— group in the infrared spectra have been tabulated.
Quantum yields and primary processes in the photolysis of HNCO vapor at 2062 Å
Authors: Woolley W. D. , Back R. A.
Published: May 2006

Quantum yields of CO, N2, and H2 have been measured in the photolysis of HNCO vapor (2–23 Torr, 25 °C) at 2062 Å. Extrapolated values at zero pressure of HNCO were about 1.0, 0.40, and 0.13 respectively. Φ(CO) and Φ(N2) increased with increasing HNCO pressure and became approximately constant at values of 1.5 and 0.6 respectively between 10 and 20 Torr. From these and other data it was concluded that two primary processes, each with a quantum yield of about 0.5, occur.[Formula: see text]The abstraction of H from HNCO by methyl radicals was found to be slow, even at 250 °C, and it was concluded that abstraction of H from HNCO plays no part in the photolysis mechanism, contrary to previous conclusions. A mechanism is suggested, based on radical–radical reactions at low HNCO pressure or high intensity, with radical reactions with HNCO becoming important at higher pressures or low intensity. It is concluded that H2 was formed in the system by reactions of H atoms.
γ-Radiolysis of cyclohexane with electron scavengers. IV. CO2 as an electron scavenger
Authors: Sagert N. H.
Published: May 2006

The room temperature liquid phase radiolysis of cyclohexane has been examined in the presence of CO2 and of CO2 with N2O. CO2 decreases the yields of all major products by scavenging electrons. It is concluded that the CO2 anion does not dissociate and that no precursors of cyclohexyl radicals are formed when it is finally neutralized by a hydrocarbon cation. No evidence that CO2 acts as an efficient O− scavenger in liquid phase cyclohexane was found. Its rate of reaction with O− appears comparable to its rate of reaction with electrons.
Far ultraviolet photolysis of carbon dioxide
Authors: Yang J. Y. , Servedio F. M.
Published: May 2006

Carbon dioxide in the pressure range of 50–600 Torr has been photolyzed at 1470 Å. An initial quantum yield of Φ(CO) = 1.0 was observed. The O2/CO ratio was 0.35 ± 0.02. While the O2/CO ratio remained constant, the rate of CO formation decreased significantly with an increase in the photolysis time. Such a lowering of the conversion rate is attributed to a light attenuation due to solid deposit being formed on the lamp window.
A new hydroxy fatty acid sophoroside from Candida bogoriensis
Authors: Tulloch A. P. , Spencer J. F. T. , Deinema M. H.
Published: May 2006

When cultured in stirred fermentors the yeast Candida bogoriensis produces extracellular glycolipids in yields of 0.5 to 1 g/l. The principal component of these is a crystalline sophorosyl hydroxy fatty acid, the structure of which has been established as 13-[(2′-O-β-D-glucopyranosyl-β-D-glucopyranosyl)-oxy]docosanoic acid 6′,6″-diacetate. The hydroxy acid portion of the molecule probably has the L-configuration. A monoacetyl glycolipid is also present as a minor component.
Steroids. CCCIX. Synthesis of new steroids with unnatural configuration
Authors: Crabbé Pierre , Cruz Alicia , Iriarte José
Published: May 2006

The preparation of several new estrane, androstane, and 19-norpregnane derivatives with unnatural configuration is discussed. A synthesis of both enantiomers (16b) and (18) from estrone is described. The structure and configuration of the compounds reported are established on the basis of their physical properties.
Conversion of (−)-α-santonin into (+)-α-cyperone
Authors: Piers Edward , Cheng Kin Fai
Published: May 2006

An efficient, 8-step synthesis of (+)-α-cyperone (1) from (−)-α-santonin (5) is described. The key steps of the sequence involve the conversion of the keto ester 8 into the substituted octalone 9, by hydrogenation of the former in the presence of the homogeneous catalyst tris(triphenylphosphine)-chlororhodium, and the pyrolysis of the keto carbonate 16, which produces (+)-α-cyperone in good yield.
The reactions of nitrosyl chloride and dinitrogen tetroxide with acetylated glycals. Acetylated 2-deoxy-2-nitroso-α-D-hexopyranosyl chlorides and nitrates and acetylated 2-nitroglycals
Authors: Lemieux R. U. , Nagabhushan T. L. , O'Neill I. K.
Published: May 2006

Reaction of nitrosyl chloride with acetylated glycals affords, with a high degree of stereospecificity, dimeric acetylated 1,2-cis-2-deoxy-2-nitroso-α-D-aldopyranosyl chlorides. Reaction of acetylated glycals with dinitrogen tetroxide, depending on the reaction conditions, can give either acetylated 2-deoxy-2-nitroso-α-D-aldopyranosyl nitrates as dimers or acetylated 2-nitroglycals. The mechanisms of these reactions are discussed.
The synthesis of some 9-furfuryl-6-substituted purines as potential antimetabolites
Authors: Hamann H. C. , Spaziano V. T. , Chou T. C. , Price C. C. , Lin H. H.
Published: May 2006

Several 9-furfuryl-6-substituted purines were synthesized by reacting 9-furfuryl-6-chloropurine (5) with the corresponding nucleophilic reagent. The mother compound (5) was prepared by direct cyclization of 4-furfurylamino-5-amino-6-chloropyrimidine (4) with a mixture of ethyl orthoformate and acetic anhydride. The diaminopyrimidine (5) was prepared by treatment of 4,6-dichloro-5-aminopyrimidine with furfurylamine in boiling water.