bluuebunny/crossref_metadata_2025 huggingface dataset:
The Rates of Some Reactions of Aqueous Hypobromous Acid and Hypobromite Ions
Authors: Lister M. W. , McLeod P. E.
Published: May 2006

The reactions of hypobromite ions, of hypobromous acid, with iodate, nitrite, and formate ions have been investigated, together with the decomposition of hypobromite ions. The pH dependence of the rate show that the reactions with formate and nitrite ions are presumably reactions of hypobromous acid. The kinetic parameters for these reactions are reported, and show some similarities to the analogous reactions of hypochlorite ions or hypochlorous acid.
Conductance Mechanism in the Solid Phase
Authors: Rastogi Pushti Prakash
Published: May 2006

From the conductance measurements, the effect of solidification of solvent on the mobility of common ions(e.g., Na+, K+ Cs+, Cl−, Br−, I−), in N-methylacetamide (NMA) solutions has been studied and the energy of activation for the conduction of electrolytes in both solid and liquid states calculated from. Arrhenius plots. The conductance behavior in solid phase (or better in solid solutions) has been indicated to be through the "hole-formation mechanism".
The Determination of Calcium Carbide and its Dissociation Products in Fused Calcium Chloride
Authors: Aksaranan C. , Dosaj V. , Morris D. R. , White S. H.
Published: May 2006

The principal constituents in molten solutions of calcium carbide in calcium chloride have been determined. The analytical results were generally within order of magnitude agreement with calculations from thermodynamic data based upon a model in which the calcium carbide is thought to be dissociated according to the equation[Formula: see text]
Reactions of Norbornen-7-one with Organolithium Reagents
Authors: Clark F. R. S. , Warkentin J.
Published: May 2006

Alkyllithium reagents (RLi: R = methyl, n-butyl, t-butyl) add to norbornen-7-one either without stereochemical preference (R = n-butyl) or with syn attack favored. This addition selectivity is qualitatively the same as that shown by corresponding alkylmagnesium reagents but competition from reduction is much less important in the case of alkyllithium reagents.Phenyllithium and vinyllithium add preferentially from the anti face, although the corresponding Grignard reagents add selectively from the syn face. Possible causes of the stereoselectivities are considered. Solvent effects on the stereochemistry of addition are small.
Thermal Decomposition of di-tert-Butyl Peroxide in Binary Mixtures near the Critical Point
Authors: Yip C. K. , Pritchard H. O.
Published: May 2006

The thermal decomposition of di-tert-butyl peroxide has been studied in the presence of high pressures of cyclopropane; the rate constant for the decomposition was determined from the sum of the rates of formation of tert-butanol and acetone. In the temperature range 125–160 °C, i.e. above the critical point of cyclopropane, concentrations of cyclopropane of between 2.6 and 3.6 mol/1 (60–80 amagats) were used; in the temperature range 100–124 °C, i.e. below the critical point of cyclopropane, an equivalent mean (liquid + gas) cyclopropane concentration was used. An Arrhenius plot of the rate constants for the peroxide decomposition is continuous through the critical point of the cyclopropane, and is indistinguishable from the best Arrhenius line representing all previous work on the reaction.However, an Arrhenius plot of the ratio of the rates of formation of tert-butanol and acetone shows a marked discontinuity at the critical point, but further investigation shows that this results from the unequal distribution of the reactant peroxide between the two phases which are present below the critical point of the cyclopropane.Less extensive series of experiments using propane, isobutane, cyanogen, and carbon dioxide as pressurizing gases confirm the pressure-independence of the rate of decomposition of di-tert-butyl peroxide: the experiments with propane and isobutane confirm the phase-independence of the rate; the propane experiments also exhibit the same apparent kinetic discontinuity at the critical point. Finally, rate-constant data are obtained for the reactions of the tert-butoxy radical with cyclopropane and isobutane, and for the addition of methyl radicals to cyanogen.
Kinetic and Equilibrium Studies of σ-Complex Formation Reactions Between 1,3,5-Trinitrobenzene and the Lyate Ions of Water, Methanol, Ethanol, n- and i-Propanol, and n-, i-, and t-Butanol in their Respective Solvents
Authors: Gan L. H. , Norris A. R.
Published: May 2006

Kinetic and thermodynamic parameters have been determined for the σ-complex formation reactions between 1,3,5-trinitrobenzene and the lyate ions of water, methanol, ethanol, n- and i-propanol and n-, i-, and t-butanol in their respective solvents. Trends in these values are interpreted in terms of specific solvation effects associated with both the base and the σ-complex. Solvent and kinetic isotope effects associated with the σ-complex formation reactions of ethoxide with 1,3,5-trinitrobenzene and 1,3,5-trinitrobenzene-d3 in ethanol and ethanol-O-d have also been evaluated.
The Influence of Heteroatom-substituted Methyl Groups and of Vinyl Groups (CR2=CR—) Attached to C-2 of 1,3-Dioxolanes on the Ease and Direction of Hydrogenolysis of the 1,3-Dioxolanes by AlH2Cl, AlH3, or LiAlH4
Authors: Davis H. A. , Brown R. K.
Published: May 2006

Heteroatom substituents on the methyl group of 2-methyl-1,3-dioxolane retard the rate of hydrogenolysis by AlH2Cl of ether solutions of the 2-substituted 1,3-dioxolanes. The effectiveness of the heteroatoms in decreasing the ease of hydrogenolysis is H < S < O < Br < NR2. This retardation is thought to be due to the destabilization of the transition state leading to the intermediate oxocarbonium ion, caused by the electronegativity of the heteroatom and/or coordination of some of the AlH2Cl with the heteroatom.AlH2Cl or AlH3 in diethyl ether at room temperature reduces 2-vinyl- or 2-[alkyl (or aryl) substituted vinyl]-1,3-dioxolanes to only the β,γ-unsaturated alkyl β-hydroxyethyl ether, the product expected from hydride ion addition to C-2 of the 1,3-dioxolane. The ease of hydrogenolysis increases with increasing alkyl (or aryl) substitution on the 2-vinyl group.LiAlH4 in diethyl ether at room temperature, or in di-n-propyl ether or 1,2-dimethoxyethane (DME) at room temperature or reflux temperature, reduces 2-vinyl-l,3-dioxolane only to α-propenyl β-hydroxyethyl ether. This product is the result of hydride addition to the β-carbon of the vinyl group accompanied by ring opening and double bond migration. Alkyl substituents attached to the vinyl group of 2-vinyl-1,3-dioxolane markedly retard the rate of hydrogenolysis by LiAlH4 in the dialkyl ethers at room temperature, but at the reflux temperature (90°) of di-n-propyl ether the 2-alkylated vinyl-1,3-dioxolanes are hydrogenolyzed, but only to the β,γ-unsaturated alkyl β-hydroxyethyl ether. In refluxing DME (80°) the 2-alkylated vinyl-1,3-dioxolanes give primarily, if not exclusively, the α,β-unsaturated alkyl β-hydroxyethyl ether. A rationale is suggested to account for these results.
Oxydation des alcènes par l'ion thallique. II. Méthode d'oxydation électrochimique catalysée par l'ion thallique
Authors: Favier R. , Freppel C. , Richer J.-C. , Zador M.
Published: May 2006

Electrochemical oxidation of organic substrates containing double bonds has been accomplished. Thalic ion is a catalyst in the oxidation:[Formula: see text]Relatively high current efficiencies are obtained while performing the oxidation at controlled potential, and by separating the anodic and cathodic compartments; this fact allows the use of this method in synthesis in cases where the thallic oxidation is selective.
The Kinetics of the Thermal Insertion Reaction of Tin(II) Halides with Cyclopentadienylnickel Carbonyl Dimer
Authors: Barrett P. F. , Clancy Ronald R.
Published: May 2006

The kinetics of the thermal insertion of SnCl2 and SnBr2 into the metal–metal bond of [π-C5H5NiCO]2 have been studied. On the basis of the kinetic data a bimolecular mechanism, involving direct attack of the tin(II) halide on the nickel dimer, has been proposed. The thermal insertion with tin(II) bromide was found to proceed with an activation enthalpy of 19.4 ± 0.2 kcal/mol and an activation entropy of −8.8 ± 0.4 cal deg−1 mol−1. For the thermal insertion with tin(II) chloride a ΔH≠ and ΔS≠ of 22.5 ± 0.2 kcal/mol and −4.0 ± 0.2 cal deg−1 mol−1, respectively, were observed.
AApplication of the Congruence Principle to Viscosities of 1-Chloroalkane Binary Mixtures
Authors: Coursey B. M. , Heric E. L.
Published: May 2006

Viscosities are reported at 25 °C in five 1-chloroalkane binary systems. Mixture data are presented both as kinematic viscosity and as excess Gibbs free energy of activation for flow. The latter quantity is correlated with the average chain length in the mixtures by graphical and analytical forms of Brønsted and Koefoed's principle of congruence. This correlation serves as a basis for prediction of mixture viscosities for 1-chloroalkane pairs having chain lengths within the observed extremes: 1-chlorobutane and 1-chlorooctadecane. Errors as kinematic viscosity by this method are less than 5.5% for the systems studied.
Optically Active Amines. Part XIII. Circular Dichroism of the N-Salicylidene Derivatives of Alkylamines
Authors: Smith Howard E. , Ensley Harry E.
Published: May 2006

Comparison of the c.d. spectra of (S)-(+)-N-salicylidene-α-phenylethylamine with those of (S)-(+)-N-salicylidene-sec-butylamine and (R)-(−)-N-salicylidene-2,2-dimethyl-3-aminobutane confirms the conclusion that the strong rotational strength shown by N-salicylidene-α- and β-phenylalkylamines is due to an interaction of the π-electron System of the phenyl group and the salicylidenimino chromophore. The sign of the Cotton effects near 255 and 315 nm shown by the N-salicylidenes of alkylamines and cycloalkylamines, when these are conformationally defined, can be correlated with their absolute configurations using a planar sector rule, similar to that used for the interpretation of the c.d. and o.r.d. spectra of N-salicylidene-α- and β-phenylalkylamines.
Reductions with Sulfurated Borohydrides. VI. The Reduction of Nitro, Nitrile, Amide, and Nitroso Groups
Authors: Lalancette J. M. , Brindle J. R.
Published: May 2006

Aromatic nitro compounds can be reduced with sulfurated sodium borohydride to the corresponding amine in high yields (≈80%) without affecting ester, nitrile, ether, halide or olefinic groups also present. With ortho-substituted nitro compounds the yields are around 60%.Primary aliphatic nitro compounds are reduced to the corresponding nitrile in high yields. Secondary aliphatic nitro compounds are reduced to mixtures of ketones and the corresponding oxime. Tertiary aliphatic nitro compounds are not reduced.Aromatic nitriles can be reduced to the corresponding amines with an excess of the reducing agent or converted to the corresponding thioamides with an excess of the nitrile.Amides and nitroso can be reduced to the corresponding amines in moderate yields.
The Reaction of Thallium with Hydrocarbons
Authors: Lalancette J. M. , Lachance A.
Published: May 2006

The exchange of the cyclopentadienyl anion between indium and thallium is reported along with exchange reactions between cyclopentadienylindiums, substituted with H, D, and CH3. The pyrolysis of numerous hydrocarbons in presence of thallium to give the corresponding cyclopentadienylthallium derivative is described and related to the structure of the starting material.
An Apparent Stereochemical Effect in MnO2 Oxidation of Some Allylic Alcohols
Authors: Fraser-Reid Bert , Carthy Bernard J. , Holder N. L. , Yunker Mark
Published: May 2006

3,4-Di-O-acetyl-D-xylal undergoes acid-catalyzed reaction with ethanol to give the anomeric mixture of ethyl 2,3-dideoxy-4-O-acetyl-D-glycero-pent-2-enopyranosides which can be separated after deacetylation. The α-D anomer 1 is readily oxidized by manganese dioxide to the α,β-unsaturated ketone but the β-D anomer 2 is inert. Thorough investigation of the 100 and 220 MHz n.m.r. spectra of 1 and 2, their acetates, and dinitrobenzoates indicates that each exists conformationally pure in the half-chair form having the benefit of the anomeric effect. Hence in the oxidizable anomer 1 the C-4 allylic hydroxyl group is pseudo-equatorial; in the unoxidizable one it is pseudoaxial. Hydrogen bonding does not appear to be the reason for failure of 2 to oxidize.The ethoxy groups of 1 and 2 are found to be ABX3 system with unusually large separation for the AB protons.
Etude polarographique des ozonides
Authors: Grignon J. , Fliszár S.
Published: May 2006

The polarographic reduction of the ozonides of stilbene and of selected ring-substituted styrenes, yielding 2 mol of aldehyde per mole of ozonide, has been studied. With the substituted styrenes a Hammett relationship is observed for the half-wave potentials. The positive ρ constant (0.20) indicates that the determining step is a nucleophilic process. Possible mechanisms are discussed.
The Solvolysis of 5,5-Diphenylcyclononyl p-Toluenesulfonate. A Reinvestigation
Authors: McIntosh John M. , Miskow M. H. , Wood Gordon
Published: May 2006

Reinvestigation of the acetolysis of 5,5-diphenylcyclononyl tosylate (1) has confirmed the absence of any transannular processes and deamination of the corresponding amine 16 gave a similar resuit. Trifluoroacetolysis of 1 caused extensive transannular hydride migration but no phenyl migration. The former may be due to secondary acid-catalyzed rearrangements.
Reactions of Carbonyl Ylides
Authors: Lown J. W. , Matsumoto K.
Published: May 2006

2,3-Diphenylindenone oxide 1 undergoes thermal 1,3-dipolar cycloadditions via a carbonyl ylide with symmetrical olefinic dipolarophiles to give (i) with cis addends mixtures of endo and exo adducts in which endo adducts generally predominate in agreement with results obtained with 1-cyclohexyl-6-(cyclohexylimino)-1a-phenylindano [1,2-b]aziridine and (ii) with trans addends adducts in which the 2-exo-3-endo product predominates. The pyrilium oxide 4 is efficiently trapped with benzyne. 1,3-Diphen-ylisobenzofuran reacts with cis-addends to give endo–exo mixtures in which the endo adducts generally predominate. 2-Acetyl-5,5-pentamethylene-2-phenyl-Δ3-1,3,4-oxadiazoline undergoes regiospecific cycloaddition via a carbonyl ylide with unsymmetrical olefinic dipolarophiles in accordance with substituent electronic effects, and with 1,4-naphthoquinone a previously postulated type of intermediate adduct is isolated.
Photocyclization Reactions of Aryl Polyenes. IV. The Syntheses of Isatogens and Isatogen-like Compounds
Authors: Leznoff Clifford C. , Hayward Roger J.
Published: May 2006

Photochemical reactions of 1-o-nitrophenyl-4-phenyl-1,3-butadiene, 1,4-di-o-nitrophenyl-1,3-butadiene, 1-o-nitrophenyl-6-phenyl-1,3,5-hexatriene, and 1,6-di-o-nitrophenyl-1,3,5-hexatriene all gave the appropriate 2-substituted isatogen. The related m- and p-nitrophenyl polyenes were inert to the irradiation conditions. A six-membered ring isatogen-like compound, 2-phenyl-3-oxo-benzo[d,e]quinoline-N-oxide was prepared by irradiation of 1-[1′-(8′-nitronaphthyl)]-2-phenylacetylene. A seven-membered ring isatogen-like compound, 6-phenyl-7-oxo-dibenzo[b,d]azepine-N-oxide, was prepared by heating 1-[2-(2′-nitrobiphenyl)]-2-phenylacetylene.
The Trifluoroacetic Acid Solvent System. Part III. The Acid, HB(OOCCF3)4, and the Solvent Autoprotolysis Constant
Authors: Harriss M. G. , Milne J. B.
Published: May 2006

The limiting equivalent conductivities, Λ0, of the acids, HB(OOCCF3)4 and HSbF5(OOCCF3), and the salt, CsB(OOCCF3)4, have been measured and found to be 22.34, 18.77, and 48.56 ohm−1 cm2 equiv−1, respectively. Calculation of the solvent autoprotolysis constant gives the value: 4 × 10−14 mol2 l−2. The salt, CsB(OOCCF3)4 is readily prepared but the parent acid, B(OOCCF3)3 could not be isolated.
Action des organomagnésiens sur les composés β-dicarbonylés V. Synthèses de β-diols bitertiaires à partir de β-hydroxycétones. Induction asymétrique 1-3
Authors: Michel Jacqueline , Canonne Perséphone
Published: May 2006

Addition of organomagnesium compounds to β-hydroxyketones with an asymmetric center gave a diastereoisomeric mixture of symmetric ditertiary β-diols, the ratio of meso and threo forms depending on the nature of the inductive group.The configurations of the β-diols were determined using their respective n.m.r. spectra in which the methyl and the methylene protons have different chemical shifts.The conformations of the β-hydroxyketones and the β-diols were studied by i.r. spectroscopy. Models for a preferred attack of the organomagnesium compounds are proposed and product-determining transition states for the reactions are also suggested.
The Crystal and Molecular Structure of 3-Chloro-3-deoxy-1,2;5,6-di-O-isopropylidene-β-D-idose
Authors: Einstein F. W. B. , Slessor K. N.
Published: May 2006

The crystal and molecular structure of 3-chloro-3-deoxy-1,2;5,6-di-O-isopropylidene-β-D-idose has been determined from three dimensional X-ray data collected by counter methods. The structure was refined by full-matrix least-squares techniques to a conventional R factor of 5.7% for the 817 observed reflections. The compound crystallizes in the orthorhombic space group P212121 with four molecules in a cell of dimensions a = 9.744(6), b = 26.76(2), c = 5.403(3) Å.The structure analysis has served to confirm the site of halogenation and that it occurs stereospecifically. The conformation of the furan ring is an envelope arrangement with C(4) displaced from the mean plane.
Dielectric and Association Behavior of 1-Propanol, 2-Propen-1-ol, and 2-Propyn-1-ol in Non-polar Solvents
Authors: Rajala G. E. , Crossley J.
Published: May 2006

Dielectric constants and losses of 1-propanol, 2-propen-1-ol, and 2-propyn-1-ol in p-xylene, and 1-propanol and 2-propen-1-ol in cyclohexane have been measured at up to 10 frequencies in the range 1–145 GHz at 25 °C. The low frequency dielectric constants have also been measured at 2 MHz. An analysis in terms of two relaxation times has been obtained for each system. The short relaxation times are relatively independent of the alcohol, its concentration, and the solvent. Conversely, the longer relaxation times lengthen with increased alcohol concentration, lengthen in the order 2-propyn-1-ol, 2-propen-1-ol, 1-propyn-1-ol and are considerably shorter in p-xylene than in cyclohexane.
An Aromatic Amine—1,3,5-Trinitrobenzene σ-Complex
Authors: Buncel E. , Webb J. G. K.
Published: May 2006

Interaction between aniline and the 1,3,5-trinitrobenzene–methoxide ion adduct 1 in DMSO solution results in spectral changes which are characteristic of σ-complex formation, the first such case involving an aromatic amine.
Sterically Hindered Aromatic Compounds. III. Acid-catalyzed Reactions of 2,4,6-Tri-t-butyl- and 2-Methyl-4,6-di-t-butylbenzyl Alcohols and Chlorides
Authors: Barclay L. R. C. , Sonawane H. R. , MacDonald M. C.
Published: May 2006

Treatment of 2,4,6-tri-t-butylbenzyl alcohol (2), the corresponding benzyl chloride (3) and methyl ether (5) with strong acids gave high yields of 1,1-dimethyl-4,6-di-t-butylindane (10). On the other hand, acid-catalyzed reactions on 2-methyl-4,6-di-t-butylbenzyl alcohol (13), chloride (16), and methyl ether (12) yielded nucleophilic substitution products. According to comparative hydride transfer reactions between triethylsilane and carbonium ions generated from 2, 3, 13, and 16 in trifluoroacetic acid, the 2,4,6-tri-t-butylbenzyl cation is very readily formed. A mechanism suggested for the formation of 10 involves this cation as an intermediate.
An X-Ray Structure Determination of the Twinned Crystals of Dinitrato-2,2′-dipyridylsilver(II)
Authors: Bushnell G. W. , Khan M. A.
Published: May 2006

The crystal structure of dinitrato-2,2′-dipyridylsilver(II) has been solved and refined to an R-value of 0.070. Four circle diffractometer measurements were obtained from the twinned triclinic crystals. The unit cell dimensions at 22 °C are: a = 697.5 ± 0.2 pm, b = 999.4 ± 0.2 pm, c = 1032.2 ± 0.2 pm, α = 113.46 ± 0.02°, β = 100.71 ± 0.02°, γ = 95.28 ± 0.02°. The space group is [Formula: see text] (No. 2) with two molecules per unit cell. The density is 2.06 ± 0.04 g cm−3 (measured), 2.02 g cm−3 (calculated). The four shortest bond lengths to silver are: Ag—O(1), 214.8 ± 1.5 pm; Ag—O(4), 213.6 ± 1.5 pm; Ag—N(1), 212.4 ± 1.6 pm; Ag—N(2), 220.7 ± 1.6 pm. These four bonds are distorted from square planar geometry with the silver atom lying 19.90 ± 0.17 pm out of the mean plane of the other four atoms. There are also long bonds to the nitrato groups of neighboring molecules: Ag—O(1′), 275.3 ± 1.3 pm; Ag—O(2″), 276.3 ± 1.6 pm. Inclusion of these bonds gives a distorted octahedral silver coordination. Though predominantly unidentate, there is a slight tendency toward bidentate bonding in both nitrato ligands: Ag—O(2), 305.8 ± 1.4 pm; Ag—O(5), 295.0 ± 1.7 pm. O(2) and O(5) approach the convex side of the distorted square planar coordination. The deviation from planarity of the closely bonded square, and angular distortions in the above mentioned octahedral coordination can be rationalized by considering the silver as eight coordinate. The bonds to silver may be grouped 4:2:2 by length or 4:3:1 by angular disposition.
The Structure and Stereochemistry of Hydroxyachillin
Authors: Bachelor F. W. , Paralikar A. B. , Itô Shô
Published: May 2006

The sesquiterpene lactone hydroxyachillin has been isolated from Artemisiafrigida Wild. The position and stereochemistry of the free hydroxyl group has been established by n.m.r. examination as well as the conformation of the molecule using nuclear Overhauser effects.
Gallium(III)-trisfluorosulfate
Authors: Storr A. , Yeats P. A. , Aubke F.
Published: May 2006

Gallium(III)-trisfluorosulfate is prepared by the reaction of gallium(III)-trichloride with either S2O6F2 or BrOSO2F. The i.r. spectrum is interpreted in terms of a polymeric compound containing bridging bidentate fluorosulfate groups only, thus resulting in hexacoordination around gallium. Gallium(III)–trisfluorosulfate is found to react with trimethylamine, however adducts of variable composition are formed.
Reactions of Unsaturated Compounds with Silicon Difluoride. Part I. Acetylene
Authors: Liu C. S. , Margrave J. L. , Thompson J. C. , Timms P. L.
Published: May 2006

The reaction of acetylene with silicon difluoride at low temperatures has been studied. Three products have been identified as volatile species after the reaction: tetrafluorodisilacyclobutene, 3,4-tetrafluorodisilahex-1-yne-5-ene, and 5,6,7-hexafluorotrisilanorborn-2-ene. Spectroscopic data for the compounds are presented, together with a possible mechanism to account for the formation of the observed products.
Reactions of Silicon Difluoride with Unsaturated Organic Compounds. Part II. Alkyl Substituted Alkynes
Authors: Liu C. S. , Margrave J. L. , Thompson J. C.
Published: May 2006

The reactions between silicon difluoride and propyne, propyne-d1, 1-butyne, 2-butyne, and 3,3-dimethyl-1-butyne were studied. In each case products resulting from combining ratios (SiF2:alkyne) of 2:1 and 2:2 were isolated and identified. The 2:1 compounds were shown to be derivatives of disilacyclobutene, while three types of 2:2 compounds were identified. These either had an open chain structure, resulting from migration of either α (to C≡C)—CH or acetylenic H, or were derivatives of disilacyclohexadiene. Rationalizations of the types of products found and of the conditions which affect the reaction mechanism are discussed.
A Selective Determination of the Proton Nuclear Relaxation Times of the Alkaloid Vindoline
Authors: Burton R. , Grant C. W. M. , Hall L. D.
Published: May 2006

An audiofrequency-pulse n.m.r. spectrometer has been used to measure the nuclear relaxation times of individual protons of the alkaloid, vindoline. For this substance in deuterochloroform solution the spin–lattice relaxation times (T1) vary between 1.15 and 1.50 s and the spin–spin relaxation times (T2) are between 0.90 and 1.40 s. The N-methyl group has the shortest relaxation time of those resonances which were measured. A discussion of the apparatus and methodology is given.
Metal Halide Ammines. II. Thermal Analyses, Calorimetry and Infrared Spectra of Fluoride Ammines and Hydrates of Bivalent Metals
Authors: Patil K. C. , Secco E. A.
Published: May 2006

Thermal analyses of bivalent metal fluoride ammines reveal that decomposition occurs in two or more steps. Calorimetric measurements along with related enthalpic values of the various decomposition steps are given.The infrared spectral data of the ammines and hydrates are compared with theoretical and some experimental values already in the literature.
π-Cyclopentadienylmanganese Thiocarbonyl Complexes
Authors: Fenster A. E. , Butler I. S.
Published: May 2006

The complete series of thiocarbonyl complexes, π-C5H5Mn(CO)3−x(CS)x(x = 1, 2, 3), have been prepared by reaction of the appropriate cis-cyclooctene derivative, π-C5H5Mn(CO)3−x(CS)x−1(C8H14), with CS2 in the presence of triphenylphosphine.
Infrared and Nuclear Magnetic Resonance Spectra of Methyl Titanium Halides
Authors: Hanlan J. F. , McCowan J. D.
Published: May 2006

Nuclear magnetic resonance and infrared spectra have been obtained for CH3TiCl3, (CH3)2TiCl2, and some related materials. The rather unusual n.m.r. data for these compounds and for C2H5TiCl3 are compared with the results for related species involving Group IVA elements and the variations are discussed in terms of n.m.r. and bonding parameters. Exchange of methyl groups between CH3TiCl3 and (CH3)2TiCl2 and between each of these compounds and (CH3)2Zn has been studied by this means. Infrared data remain difficult to interpret, and unambiguous assignment of bands has not been achieved.
Nuclear Recoil Reactions in Organomanganese Compounds. VI. IMn(CO)5 and BrMn(CO)5
Authors: Jong I. G. De , Wiles D. R.
Published: May 2006

Radiochemical reactions of 82Br, 128I, and 56Mn have been studied in neutron-irradiated BrMn(CO)5 and IMn(CO)5. The parent compounds were found to contain 49 and 28% of the 82Br and 128I, but only 6 and 10% of the 56Mn, respectively. The dimeric [XMn(CO)4]2 accounted for 28% of the 82Br, but only about 2% of the 56Mn. Some 56Mn2(CO)10 was also found. The radiochemical yields of several products were found to increase substantially on thermal treatment of the target material.Reaction pathways are suggested which can account for the thermal effects, which involve halogen atom transfer and carbonyl transfer in the solid.
A Quantum Chemical Conformational Analysis of the Ethylenediamine Molecule
Authors: Hadjiliadis N. , Diot A. , Theophanides T.
Published: May 2006

The conformational analysis of the ethylenediamine molecule has been studied by the LCAO-EHMO calculation method. The results indicate that the most stable conformation of the molecule is the gauche form, in which the angle N—C—C—N is ca. 63.0° measured from the cis form. This is in agreement with experimental data and can explain the fact that the ethylenediamine in its chelate complexes is always in the gauche form. In addition, the present results indicate that the trans form is the next most stable conformation of ethylenediamine in agreement with experimental results on bridging ethylenediamine metal complexes.
The Reactions of N,N′-Dimethylethylenediamine with Cyclic Phosphonitrilic Halides
Authors: Chivers T. , Hedgeland R.
Published: May 2006

The reactions of N,N′-dimethylethylenediamine with the cyclic phosphonitrilic halides N3P3F6, N4P4F8, N3P3Cl6, and N4P4Cl8 lead to spiro halogenophosphonitrilic imidazolidines of the type[Formula: see text](n = 3, 4; x = 1, 2; X = Cl, F) together with polymeric materials. Structure[Formula: see text]has also been prepared by fluorination of the corresponding chloride with KSO2F and from N3P3F6 and[Formula: see text]The 1H and 19F n.m.r., i.r., and mass spectra of the phosphonitrilic imidazolidines are discussed.
Nuclear Magnetic Resonance Studies of the Solution Chemistry of Metal Complexes. III. Acetylglycine Complexes of Cadmium, Zinc, and Lead
Authors: Rabenstein Dallas L.
Published: May 2006

The aqueous solution chemistry of the cadmium, zinc, and lead complexes of acetylglycine has been investigated by proton magnetic resonance spectroscopy. These systems were investigated as models for the interaction of cadmium, zinc, and lead with the C-terminal end of peptides and proteins. The acid ionization constant of acetylglycine (pKa = 3.44) and the formation constants of the cadmium (log Kf1 = 1.23), zinc (log Kf1 = 0.86), and lead (log Kf1 = 1.38, log Kf2 = 1.20) complexes at 25 °C were determined from chemical shift measurements (Kf1 = [ML+]/[M2+][L−]; Kf2 = [ML2]/[ML+][L−]). The rates of exchange of the peptide proton of acetylglycine in the free and complexed forms with solvent protons were measured from exchange-broadened n.m.r. spectra. The exchange rate of the peptide proton increases when the acetylglycine is complexed by these metals; in the case of the cadmium–acetylglycine complex the exchange rate is 53 times faster. The potential metal ion binding sites at the C-terminal end of peptides are discussed, and the possibility of chelation through an oxygen atom of the carboxylate group and an atom of the peptide linkage is considered.
Mechanism of Alcohol to Ester Rearrangement in Phosphorus Compounds
Authors: Janzen A. F. , Smyrl T. G.
Published: May 2006

The kinetics of the base-catalyzed rearrangement of dialkyl 2-hydroxy-1,1,1,3,3,3-hexafluoroisopropyl-phosphonate, (RO)2P(O)C(OH)(CF3)2 to 1,1,1,3,3,3-hexafluoroisopropyldialkyl phosphate, (RO)2P(O)OCH(CF3)2, where R = methyl, ethyl, n-butyl, have been studied. Energies of activation and entropies of activation have been obtained and the base strength of the catalyst has been varied. A mechanism is proposed to account for the results.
The Effect of Pressure on the Rate of Acetolysis of a Charge-transfer Complex
Authors: Williams R. K. , Loveday J. J. , Colter A. K.
Published: May 2006

Rates of acetolysis of the π acceptor 2,4,7-trinitro-9-fluorenyl p-toluenesulfonate, with and without added 9-methylanthracene donor, have been measured at 1, 680, and 1362 atm at 55.2 °C. The volume of activation for acetolysis of uncomplexed ester was −27 cm3 mol−1 while that for acetolysis of the 1:1 complex was −33 cm3 mol−1, relative to uncomplexed reactants. The mechanistic significance of these results is discussed.
Fluorescence and Phosphorescence of 2,3-Pentanedione
Authors: Jackson A. W. , Yarwood A. J.
Published: May 2006

The fluorescence and phosphorescence yields on photolysis of 2,3-pentanedione were investigated at various temperatures. The processes involved in the formation and removal of both the singlet and triplet states are considered. The data agree qualitatively and quantitatively with the results of an earlier study of the lifetime of the triplet state. It is shown that delayed fluorescence is not observed in the pentanedione system. A mechanism is proposed that can correlate the temperature variation of both the lifetime and quantum yield data.
Emission and Deactivation of the Excited States of 2,3-Pentanedione
Authors: Jackson A. W. , Yarwood A. J.
Published: May 2006

Vibrationally excited singlet and triplet states of 2,3-pentanedione are formed by photolysis at 365 nm. The processes removing these excited states in the gas phase are studied by measuring the fluorescence and phosphorescence yields. Fluorescence can occur from the vibrationally excited, as well as the vibrationally equilibrated, singlet state. The fluorescence and phosphorescence data are considered in terms of mechanisms which involve either weak or strong collisions. Although the data cannot distinguish between the alternatives, there are two significant conclusions. The fluorescence data require that emission occur from at least two levels in the singlet manifold. To explain the phosphorescence data, the highest emitting singlet level must not lead to a vibrationally equilibrated triplet state.
Rearrangement Studies with 14C. XXXVI. Solvolysis of 1-14C-2-Phenylethyl Tosylate in Aqueous Acetic Acid with or without Added Sodium Azide
Authors: Lee C. C. , Unger D. , Vassie Sharon
Published: May 2006

Solvolyses of 1-14C-2-phenylethyl tosylate (1-OTs-1-14C) were carried out in HOAc and H2O solvent systems with or without added NaN3. In the absence of added azide ion, the products obtained from a given solvent mixture of HOAc–H2O, 1-OAc-14C, and 1-OH-14C, showed essentially the same extent of rearrangement of the 14C-label from C-1 to -2. In the presence of added azide ion, the rearrangement in the 1-N3-14C was less than that found in the 1-OAc-14C or 1-OH-14C. The results are interpreted in terms of concurrent direct displacement to give product and product formation from the ethylenephenonium ion.
Acidity Function Behavior in Aqueous-organic Solvents. I. The H0, and HA Functions in 70% DMSO–H2O
Authors: Yates Keith , Welch Graeme
Published: May 2006

The H0, [Formula: see text] and (in part) the HA acidity functions have been determined in 70% DMSO–water for the sulfuric acid concentration range 0–85%. In sharp contrast to purely aqueous acid systems the H0 (primary aniline) and [Formula: see text] (tertiary aniline) scales in DMSO–water are closely parallel over a wide range of acidity. This provides clear experimental demonstration that linearity of log (ionization ratio) vs. acidity function with unit slope is not a sufficient condition that a base is obeying a given acidity function. When the three acidity functions in DMSO–water are shifted to a purely aqueous standard state, their order is completely reversed from that observed in aqueous acids. These differences in behavior are discussed in terms of cation solvation by DMSO molecules only.
Radiation-induced Oxidation of 2-Propanol by Nitrous Oxide in Alkaline Aqueous Solution
Authors: Burchill C. E. , Wollner G. P.
Published: May 2006

The radiation-induced oxidation of 2-propanol to acetone by N2O in alkaline aqueous solution proceeds via a free radical chain mechanism independent of pH above 12.5. The results are explained by abstraction of H from 2-propanol by O− at both the α and β positions (85% α attack). Chain propagation is by reaction of the α radical anion, (CH3)2ĊO−, with N2O with a rate constant of (3.8 ± 0.4) × 104 M−1 s−1 and by reaction of the β radical, ĊH2(CH3)CHOH, with 2-propanol to give the α radical with a rate constant of 430 ± 30 M−1 s−1.The conclusions are supported by the demonstration of kinetic isotope effects for selectively deuterated alcohols.
Thermolysis of γ-Phenylazo-γ-valerolactone
Authors: Lui H. , Warkentin J.
Published: May 2006

γ-Phenylazo-γ-valerolactone decomposed at 230° to 4,5-dihydro-6-methyl-2-phenyl-3(2H)-pyridazinone and to 6-methyl-2-phenyl-3(2H)-pyridazinone.
Anomalous Rate Laws in the Halogenation of Carbon Tetrahalides
Authors: Dunning B. K. , Pritchard H. O.
Published: May 2006

The initial rate of bromination of carbon tetrachloride is independent of surface-to-volume ratio and can be fitted to a rate law which assumes that the rate-determining step is Br + CCl4 → BrCl + CCl3; however, the overall temperature coefficient of the rate is inconsistent with the known thermochemistry of the system. The same anomaly has been reported recently in the fluorination of trichlorofluoromethane by Foon and Tait, and similar inconsistencies occur in the fluorination of carbon tetrachloride and the chlorination of bromotrichloromethane.
Technetium Chlorides and Oxochlorides
Authors: Guest A. , Lock C. J. L.
Published: May 2006

We have been unable to prepare TcCl6 by the method published previously even though our reaction between Tc and Cl2 gave products which appeared the same. TcO3Cl and TcOCl4 have been prepared and fully characterized for the first time.
The Total Synthesis of (±) Ochrobirine
Authors: Nalliah B. , Ahmed Q. A. , Manske R. H. F. , Rodrigo R.
Published: May 2006

The total synthesis of (±) ochrobirine is described.
Studies of Organophosphorus Derivatives. Part I. Nuclear Magnetic Resonance Studies of the 2-Oxo-1,3,2-dioxaphosphorinane System
Authors: Hall L. D. , Malcolm R. B.
Published: May 2006

The n.m.r. spectra of a series of simple derivatives of the 2-oxo-1,3,2-dioxaphosphorinane system are discussed in terms of the favored conformations of the derivatives and the stereospecific dependencies of vicinal31P—O—C—1H couplings. Attention is drawn to a type of "deceptively-simple" ABX spectrum which is commonly found for the n.m.r. spectra of substances containing one or more heteronuclear species.
Chemistry of the Transition Metals. II. Reaction of Branched Alkyl Chlorides with Titanium
Authors: Summers W. R. , Harrod J. F.
Published: May 2006

Except for t-butyl chloride, the 1- and 2-methyl substituted ethyl chlorides reacted at ambient temperatures with clean titanium surfaces to produce mixtures of the corresponding alkanes and alkenes; t-butyl chloride gave only isobutene. At elevated temperatures (80–150 °C depending on reactant) the branched alkyl chlorides underwent clean, catalytic dehydrochlorination on hydrochlorinated titanium films to give gaseous olefin and hydrogen chloride, in contrast to the previously observed dehydrohalogenation of n-alkyl halides, where metal was consumed continuously in a non-catalytic fashion.The kinetics of the dehydrochlorination were exceptionally simple and reproducible for a heterogeneous reaction and all reactions were first order in reactant. The reactivity order was t-butyl > i-propyl > neopentyl > i-butyl (ca. 106:6:3:1). Although a slight dependence of activation energy on reactant pressure was observed, all reactants gave a limiting activation energy of 15.5 ± 0.5 kcal/mol and the large variation in activity is attributed to differences in the Arrhenius pre-exponential factor.It is proposed that the non-catalytic and catalytic dehydrohalogenation reactions proceed by different mechanisms, the former via a dissociative chemisorption of the carbon–halogen bond and the latter via a concerted, surface-assisted HCl elimination.
Absolute Rate Constants for Hydrocarbon Autoxidation. XXI. Activation Energies for Propagation and the Correlation of Propagation Rate Constants with Carbon–Hydrogen Bond Strengths
Authors: Korcek S. , Chenier J. H. B. , Howard J. A. , Ingold K. U.
Published: May 2006

The rate constants, kp, for the abstraction of a hydrogen atom from a wide variety of organic substrates at 30° have been correlated with the strengths of the C—H bond that are broken, D[R—H] (in units of kcal/mol). Two empirical relations have been derived, one for tertiary peroxy radicals,[Formula: see text]and one for secondary peroxy radicals,[Formula: see text]These equations hold extremely well for hydrocarbons and reasonably well for substrates containing heteroatoms. The activation energies and pre-exponential factors for the oxidation of some hydrocarbons by t-butylperoxy radicals have been measured and the empirical relation[Formula: see text]derived. If D[t-ROO—H] is taken as 88 kcal/mol, this yields the Polanyi equation,[Formula: see text]where ΔH is the heat of the hydrogen abstraction reaction. These empirical equations permit the calculation of the rate constants for chain propagation in the autoxidation of many organic substrates at 30° and also at other temperatures.
A New Indoline Rearrangement
Authors: Dave Vinod , Stothers J. B. , Warnhoff E. W.
Published: May 2006

The keto pyrrolidone 2 in the presence of acid produces the enamine 3a and the rearranged quinolone 4. Evidence is presented for the mechanism of this new rearrangement, the key step being a remarkably facile opening and reclosure of the indoline ring [Formula: see text] which even occurs in acetic acid.
Synthesis of cis-Jasmone and Dihydrojasmone
Authors: Ho Honor C. , Ho Tse-Lok , Wong C. M.
Published: May 2006

cis-Jasmone and dihydrojasmone have been synthesized from levulonitrile by a four-step reaction sequence. Application of ceric ammonium nitrate for dethioketalization is described.
Dielectric Studies. Part XXXIV. Relaxation Evidence for Complex Formation of 1,4-Dioxan with Chelated Ring Systems
Authors: Magee M. D. , Walker S.
Published: May 2006

The dielectric constant (ε′) and loss factor (ε″) of solutions of (i) 8-hydroxyquinoline in cyclohexane, carbon tetrachloride, p-xylene and 1,4-dioxan, (ii) o-nitrophenol in n-heptane, cyclohexane, carbon tetrachloride, and 1,4-dioxan, (iii) 2,4-dinitrophenol in 1,4-dioxan, and (iv) 2,6-dinitrophenol also in 1,4-dioxan have been recorded at four microwave frequencies and at 25 °C. A comparison of the relaxation time data of 1-nitro-naphthalene with that of 8-hydroxyquinoline in a number of solvents indicates that a strong specific interaction occurs between the latter solute and the solvent 1,4-dioxan which leads to the formation of a complex. In addition, a comparative study of nitrobenzene and o-nitrophenol indicates a similar phenomenon. Strong interaction of the 1,4-dioxan with an atom or atoms in the chelated ring system appears to take place which produces a larger reorienting species than the solute molecule itself and appreciably lengthens the relaxation time, although the data do not establish the point of attachment of the 1,4-dioxan to the chelated ring. The complex formation is accompanied by an additional component to the dipole moment. For the dinitrophenols significant interaction with the solvent p-xylene complicates the interpretation of the relaxation time data, although in the 2,4-dinitrophenol the formation of a complex is indicated in 1,4-dioxan.
The Oxygenation of 2-Oxazolin-5-ones: A New Synthesis of Imides
Authors: Bisson R. , Yeats R. B. , Warnhoff E. W.
Published: May 2006

In the presence of mild base such as triethylamine, the two 4-alkylidene-2-phenyl-2-oxazolin-5-ones, 1 and 8, rapidly absorb oxygen at room temperature with the loss of carbon dioxide and the formation of the imides 4 and 10. The imide probably arises by decomposition of a hydroperoxide resulting from the reaction of oxygen and the anion of the oxazolinone. A hydroperoxide intermediate will also account for the origin of the acidic by-products 6a and 11a. The 2-methyl-2-oxazolin-5-one 14 did not react with oxygen at room temperature; at 60° some reaction occurred but no imide was formed.
Kinetics and Mechanism of Decarboxylation of some Pyridinecarboxylic Acids in Aqueous Solution
Authors: Dunn G. E. , Lee Gordon K. J. , Thimm Harold
Published: May 2006

The first-order rate constants for decarboxylation of picolinic and five substituted picolinic acids in buffered aqueous solution at 150° and ionic strength 1.0 increase as pH increases above 0, go through a maximum at pH near 1, then level off at about half the maximum. For quinolinic acid at 95° the rate maximum occurs at the isoelectric pH. It is therefore concluded that the anion decarboxylates about half as fast as the isoelectric species. Anion and isoelectric species show similar carboxyl-carbon kinetic isotope and substituent effects, so they probably decarboxylate by similar mechanisms. The methyl betaine of picolinic acid decarboxylates about 200 times faster than the anion. From these facts it is concluded that the isoelectric species which decarboxylates is probably zwitterion rather than neutral acid, and that anion and zwitterion decarboxylate by loss of carbon dioxide to form 2-pyridyl carbanion and ylid, respectively. The slower decarboxylation of isoelectric species compared to betaine suggests that only a small fraction of the isoelectric species is zwitterion. However, qualitative estimates from spectra of the fraction of zwitterion present in the isoelectric species at 150° suggest that this cannot be the whole explanation. The relative reactivities of the 2-and 4-positions are similar for decarboxylation and hydrogen exchange in pyridinium ions, but not in the unprotonated species.
Five-membered Heterocyclic Thiones. Part II. Oxazole-2-thione
Authors: Lacasse G. , Muchowski J. M.
Published: May 2006

Oxazole-2-thione was prepared by the condensation of glycolic aldehyde and thiocyanic acid. It was shown by i.r. spectroscopy that oxazole-2-thione, as well as its 4-methyl- and 4,5-dimethyl derivatives, existed as the thione form in solution.
The Stereochemistry of the Addition of Two Diazoalkanephosphonates to Norbornene and Norbornadiene; Photolysis of the Adducts. An Entry into the Dimethyl tricyclo[2.1.1.02.4]octyl Phosphonate System
Authors: Callot Henry J. , Benezra Claude
Published: May 2006

not available
Transient Response of the System Al/Al2O3/Electrolyte. Part II. A.c. Impedance Measurements During Steady-State Film Growth
Authors: Goad D. G. W. , Dignam M. J.
Published: May 2006

Experiments are described in which the a.c. impedance of the system Al/Al2O3/electrolyte (glycol–borate) is measured under conditions of steady-state film growth. Using an equivalent circuit of a resistive and capacitive element in parallel, the results are presented in the form of the a.c. conductance, σac, and effective dielectric constant, Keff, of the oxide film as a function of the d.c. current density, I0, and angular frequency ω. The results show that σac/I0 and Keff vary with (ω/I0), but within experimental error are independent of ω and I0 separately. The dielectric relaxation model, assuming two ion-current-driven relaxation processes and using the constants determined in Part I, reproduces the data almost within experimental scatter. A poorer fit is achieved if only one relaxation process is assumed.
A Nuclear Magnetic Resonance Study of Norbornadiene Partially Oriented in a Nematic Phase
Authors: Burnell E. E. , Diehl P.
Published: May 2006

The n.m.r. spectrum of norbornadiene partially oriented in a nematic phase has been measured, and the geometry of the proton skeleton has been determined. The results are compared with several electron diffraction studies, and are only consistent with those in which the angle C1C7C4 is approximately 92°.
Crystal Structure of and Electron Spin Resonance of Mn2+ in MgV2O6
Authors: Ng Hok Nam , Calvo Crispin
Published: May 2006

MgV2O6 crystallizes in the monoclinic space group C2/m with lattice parameters a = 9.279(7), b = 3.502(2), c = 6.731(6) Å and β = 111.77(6)° with Z = 2. The structure was refined, at room temperature, utilizing 593 symmetry independent reflections, by full matrix least squares to a final R value of 0.032. The structure consists of Mg2+ lying at a site of 2/m symmetry octahedrally coordinated to oxygen atoms with a mean separation of 2.140 Å. All the remaining atoms lie in crystallographic mirror planes with the V ion coordinated to six oxygen atoms with bond distances ranging from 1.666 to 2.671 Å. The spin Hamiltonian parameters for Mn2+ were determined at room temperature and again at liquid N2 temperatures. As these values are invariant with temperature there is no indication of a phase transformation in Mg(VO3)2 to a lower symmetry space group. The spin Hamiltonian parameters are gx = 2.0042, gy = 2.0090, gz = 2.0005; D = −459 G, E = 65 G, and A = −78 G with one of the principal axes, X, parallel to the b-axis and the Z-axis at an angle of 5° to the c-axis.
The Crystal Structure of Caesium Oxotetrafluorovanadate(V)
Authors: Bushnell G. W. , Moss K. C.
Published: May 2006

The crystal structure of caesium oxotetrafluorovanadate(V) has been solved and refined to an R-value of 0.070 using diffractometer measurements. The cell dimensions are: a = 548.4(2) pm, b = 634.2(2) pm, c = 1403.4(3) pm. The space group is Pnma (No. 62) with four formula units per cell. Each vanadium atom lies 32.6 pm above the base of a tetragonal pyramid with oxygen at the apex (V=O length = 152.9 pm) and fluorine at the four base corners (mean V—F length = 178.8 pm). The tetragonal pyramids are linked by cis-fluorine bridges involving a long V—F bond (V—F(21) = 231.2 pm) to give an anionic chain structure. Structural relationships with other fluorides and oxide-fluorides are noted, and the bond lengths are discussed.