bluuebunny/crossref_metadata_2025 huggingface dataset:
Photoreactions of Nitroso Compounds in Solution. XXII. Stereochemical Consequences of the Photoaddition of N-Nitrosopiperidine to Conjugated Acyclic Dienes: a Nuclear Magnetic Resonance Study of Enone Oximes
Authors: Chow Y. L. , Colón C. J. , Quon H. H. , Mojelsky T.
Published: May 2006

In the presence of an acid, photoexcited N-nitrosopiperidine adds to conjugated acyclic 1,3-dienes to give the 1,4-adducts as the major product in addition to 1,2-adducts. In the photoaddition to 1,3-pentadienes the reverse 4,1-adduct and 4,3-adducts are also identified. These results suggest that a singlet photoexcited N-nitrosopiperidine–acid complex rapidly decays to piperidinium radical which irreversibly attacks the dienes as the first step, followed by either a short propagation step or a termination step to give C-nitroso compounds. The C-nitroso compounds are rapidly removed by irreversible tautomerization to the final oximes. The reactivity of the piperidinium radical toward conjugated double bonds decreases in the order of RCH=CH2 > cis-RCH=CHR > trans-RCH=CHR. This mechanism is in accord with the following stereochemical results. Firstly, the newly-formed double bond in the 1,4-adduct (or the adduct of the reverse orientation) is exclusively trans-oriented. Secondly, the remaining double bonds in the 1,2-adducts maintain their original stereochemistry.The stereochemistry of the photoadducts, enone oximes 1–11, was determined by means of n.m.r. spectroscopy. From the correlation of the n.m.r. chemical shifts of these enone oximes it has been shown that (i) the α-olefinic proton generally resonates at a lower field than the β-olefinic proton (with one exception) and (ii) in changing from CDCl3 to an aromatic solvent the α-olefinic proton and the α′-alkyl protons are de-shielded by 0.3–0.05 p.p.m. while the β-olefinic proton is shifted only slightly either to a higher or a lower field. It is observed that the order of the chemical shifts of the olefinic protons and the aromatic solvent effects on the chemical shifts in these enone oximes are both opposite to those observed in enone systems.
Densities, Excess Volumes, Surface Tensions, Viscosities, and Dielectric Constants of the Systems: Methanol–Cyclohexane, Acetone–Methanol, Acetone–Cyclohexane, and Methanol–Cyclohexane–Acetone
Authors: Campbell A. N. , Anand S. C.
Published: May 2006

The density, dielectric constant, change of volume on mixing, refractive index, surface tension, and viscosity of the methanol–cyclohexane system have been investigated experimentally at temperatures ranging from 25° to 50°. The same properties of the binary systems acetone–methanol and acetone–cyclohexane, as well as of the ternary system methanol–cyclohexane–acetone were determined experimentally at 25°. The critical region of the partially miscible system methanol–cyclohexane has been investigated by determining the above physical properties at temperatures above and below the critical solution temperature. A similar investigation of the ternary system has been made, isothermally at 25°, by investigating solutions lying in the neighborhood of the plait point.The surface tension or a derived function of it, viz. the molecular surface energy, does not show a horizontal portion of the isotherm in the methanol–cyclohexane system, but the ternary system does show such a constant surface tension, probably fortuitously, all along the tangential line. The viscosity exhibits anomaly.All the systems show azeotropic behavior. The methanol–cyclohexane and acetone–cyclohexane systems show marked deviations in molar polarization from linearity and this agrees with the thermodynamic data, which indicate larger than unity values for the activity coefficients of the components' behavior (1). The viscosity isotherms of all these systems give no indication of the formation of any stable compound.
Reactions of Chloramines with Ag(0) and Ag(I) States
Authors: Edwards O. E. , Vocelle D. , ApSimon J. W.
Published: May 2006

Reactions of N-chloroazacyclooctane and N-chloroazacyclononane are described which give good yields of bicyclic amines. These are: (a) short chain homolytic reactions involving neutral nitrogen radicals initiated by ferrous ion or metallic silver; (b) apparent homogeneous reactions involving silver ion and bases; (c) reactions using silver oxide suspension which also require added bases.Both rate and product composition for (b) and (c) are sensitive to oxygen indicating that they are homolytic processes, probably initiated by traces of silver metal. No evidence for involvement of discrete nitrenium ions was found. However, reaction of N-chloroisoquinuclidine with silver ions has the character of a heterolytic process, giving products completely distinct from those from its homolytic decomposition. The addition of neutral piperidino radicals to styrene is described.
Photoamidation of 3,4,6-Tri-O-acetyl-1,2-dideoxy-D-arabino-hex-1-enopyranose
Authors: Rosenthal Alex , Zanlungo A.
Published: May 2006

The acetone-initiated photochemical addition of formamide to 3,4,6-tri-O-acetyl-1,2-dideoxy-D-arabino-hex-1-enopyranose (1) afforded 3,4,6-tri-O-acetyl-2,6-anhydro-3-deoxy-D-gluco-heptonamide (2), 3,4,6-tri-O-acetyl-2,6-anhydro-3-deoxy-D-manno-heptonamide (3), and3,4,6-tri-O-acetyl-1,5-anhydro-2-C-carbamoyl-1,2-dideoxy-D-gluco-hexitol (4) in a combined yield of about 75% (the ratio of yields of 2,3, and 4 was approximately 2:2:3). In addition, trace quantities of the epimeric manno branched-chain adduct of 4, and acetone adducts of 1 were formed. Lithium aluminum hydride reduction of 4 yielded a branched-chain aminopolyol, isolated as its N-acetyl derivative.
Reactions of Nitro Sugars. XXVI. Analysis and Separation of Stereoisomers by Nuclear Magnetic Resonance Spectroscopy and Column Chromatography of Benzylidene Derivatives
Authors: Baer Hans H. , Rank Werner
Published: May 2006

Stereoisomeric methyl 4,6-O-benzylidene-3-deoxy-3-nitrohexopyranosides proved to be distinguishable by the chemical shifts of their benzylidene methine proton signals, and ratios of such isomers in mixtures could be estimated by signal integration. The method was applied to a reinvestigation of the epimeric distributions in which methyl 3-deoxy-3-nitro-α-D-hexopyranosides arise, firstly, in the nitromethane cyclization of 2-O-[(S)-formyl(methoxy)methyl]-(R)-glyceraldehyde and, secondly, in their base-catalyzed configurational equilibration via nitronates. Previous results were essentially confirmed as far as the preferred configurations are concerned but require some revision as to the relative abundance of less favored configurations. By preparative chromatography of benzylidene acetals and subsequent debenzylidenation, some nitrohexopyranosides of the a-D series were isolated for the first time in crystalline condition. Separation of isomers in the β-D series was improved by use of chromatography and by a new method involving differential reactivities of compounds toward alkali.
Five-coordinate Tertiary Phosphine and Arsine Adducts of Copper(hexafluoroacetylacetonate)2
Authors: Zelonka R. A. , Baird M. C.
Published: May 2006

1:1 adducts of copper(hexafluoroacetylacetonate)2 with a number of phosphorous and arsenic ligands have been prepared and characterized by their electronic, infrared, n.m.r. (1H and 19F), and e.s.r. spectra.
Studies on the Decomposition of Tetra-alkylammonium Salts in Solution. V. Rates and Activation Parameters of Salts Containing Substituted-benzyl or Other Active Groups
Authors: Ko E. C. F. , Leffek K. T.
Published: May 2006

First order rate constants and activation parameters are reported for the decomposition in chloroform and acetone solvents of a series of 4-substituted-benzylphenyldimethylammonium bromides and iodides and also of a series of tetra-alkylammonium bromides which contain no benzyl group. The results are discussed in terms of general mechanism of these reactions, which are unimolecular "ionic internal" nucleophilic substitutions
Complexes de platine avec des dérivés acétyléniques Pt(R1R2C(OH)—C≡C—C(OH)R1R2)2
Authors: Rochon Fernande D. , Theophanides T.
Published: May 2006

Complexes of the type Pt(ac)2 where ac = R1R2C(OH)—C≡C—C(OH)R1R2 have been studied. The compounds are mononuclear, non ionic, and diamagnetic. The experimental results seem to indicate that the ligands are not rearranged in the complex. The order of the triple bond has been partially reduced and there is an important distortion of the acetylenic molecule. A structure with the two ligands hydrogen bonded is proposed.The complexes Pt(ac)2 react with triphenylphosphine according to the following equation:[Formula: see text]
The Hydrolysis of t-Butyl Chloride in Aquo-Organic Mixtures: Heat Capacity of Activation and Solvent Structure
Authors: Robertson R. E. , Sugamori S. E.
Published: May 2006

The temperature dependence of the rate of solvolysis of t-butyl chloride in mixtures of tetrahydrofuran and of acetonitrile in water have been determined. In the high-water range both minor co-solvents lead to a reduction in the value of ΔH≠ similar to that found previously where alcohol was the co-solvent. However, a remarkable difference in the values of [Formula: see text] across the same concentration range reflected a difference in the effect of these two co-solvents on the structural properties of the several solvent media. Where tetrahydrofuran or alcohols are the minor co-solvent, [Formula: see text] becomes much more negative until that concentration is reached where the quasi-aqueous structure collapses. Where acetonitrile is the minor co-solvent [Formula: see text] becomes more positive relative to the value found for hydrolysis in water until a value of about −40 cal deg−1 mol−1 is reached. The implication of these findings concerning the nature of solvation of weakly polar solutes in such mixtures is discussed.
Nuclear Magnetic Resonance Studies of some Trimethyl Tin Carbamates
Authors: Lemire A. E. , Thompson J. C.
Published: May 2006

The low temperature n.m.r. spectra of some trimethylstannyl esters of N,N-dimethylcarbamic acid, N,N-dimethyldithiocarbamic acid, and N,N-dimethylmonothiocarbamic acid have been examined. Activation parameters for hindered rotation about the C—N bond in the trimethylstannyl ester of N,N-dimethylmonothiocarbamic acid have been determined to be: in hexane solution, Ea = 17.0 + 0.5 kcal/mol, [Formula: see text][Formula: see text][Formula: see text] in chloroform solution, Ea = 19.9 ± 0.5 kcal/mol, [Formula: see text][Formula: see text][Formula: see text]not available
Primary Yields and Mechanisms in the Radiolysis of N2O from High Intensity Electron Pulse Irradiations of N2O–O2 Mixtures
Authors: Willis C. , Boyd A. W. , Bindner P. E.
Published: May 2006

The yields of N2, O2, NO, and O3 have been measured from the Febetron radiolysis of N2O–O2 mixtures with and without SF6. A mechanism consistent with the yields from 0–100% O2 and with known ionic abundances and reaction rate data has been derived. The major features of this mechanism are both dissociative neutralization of N2O+ and excitation of N2O to give N2(X1Σ) and O(1D) and smaller amounts of N2(B3Π) and O(3P). The large yields of NO and N2 observed are mainly due to reaction of O(1D) with N2O to give both N2 and O2 and NO.
Réaction du sulfure de bore avec quelques composés difonctionnels
Authors: Jerumanis S. , Begin P. A. , Cong D. Vu
Published: May 2006

Catechol reacts with boron sulfide to give 2,2′-o-phenylenedioxybis-(1,3,2-benzodioxaborole) (1) while only the hydroxyl function of salicylic acid reacts to give a quantitative yield of tris(o-carboxylphenoxy)borane (3). Phthalic acid is dehydrated to phthalic anhydride, but succinic acid and maleic acid have been found inert to the action of the boron sulfide.
Branched-chain Nitro Sugars. Methyl 4,6-O-Benzylidene-2,3-dideoxy-3-C-nitromethyl-α-D-ribo-hexopyranoside
Authors: Rosenthal Alex , Schöllnhammer Gunter
Published: May 2006

The preparations of methyl 3-O-acetyl-4,6-O-benzylidene-2-deoxy-3-C-nitromethyl-α-D-ribo-hexopyranoside (4) and the arabino-epimer (5) are described. Schmidt–Rutz degradation of 4 and 5 afforded a cis–trans mixture of the branched-chain carbohydrate nitroolefins 6 which were stereoselectively reduced with sodium borohydride to yield methyl 4,6-O-benzylidene-2,3-dideoxy-3-C-nitromethyl-α-D-ribo-hexopyranoside (7). The utility of circular dichroism studies in determining the configuration of nitro sugars is discussed.
Nuclear Magnetic Resonance Spectra of Methyl Substituted 6-Aryl [1,2,4] triazolo [4,3-d] tetrazoles
Authors: Butler R. N.
Published: May 2006

The n.m.r. spectral properties of a range of the title compounds are reported and discussed.
Relative Rate of Reaction of O(1D2) with N2O
Authors: Paraskevopoulos G. , Symonds V. B. , Cvetanović R. J.
Published: May 2006

The rate of reaction of O(1D2) with N2O relative to the rate of its reaction with neopentane has been determined by a competitive method. The value obtained, [Formula: see text] is in good agreement with several values in the literature. It is also found that N2O does not deactivate O(1D2) to O(3P) but reacts with it to form products.
INDO Molecular Orbital Calculations on the Conformational Dependence of Long-range Spin–Spin Coupling of Methyl Protons in Toluene, p-Fluorotoluene, and the Xylenes
Authors: Wasylishen R. , Schaefer T.
Published: May 2006

The conformational dependence of the nuclear spin–spin coupling from methyl protons to ring protons, to the fluorine nucleus, and to protons of other methyl groups in toluene, p-fluorotoluene, and the xylenes is computed by the finite perturbation technique in the INDO approximation of molecular orbital theory. The calculated coupling over six bonds to the proton in the para position agrees quantitatively with experiment and its predicted dependence on the rotational angle of the methyl group supports a commonly assumed π electron mechanism for the transmission of spin information between the nuclei. Similar remarks apply to the fluorine nucleus in p-fluorotoluene. The couplings over five and four bonds to the protons in the meta and ortho positions display a more complex angular dependence and the former can be interpreted in terms of a dominant σ electron mechanism. The coupling between protons in different methyl groups in the ortho and meta xylenes is calculated as rather larger than the values observed in their derivatives and in the main shows the behavior expected from a π electron mechanism. Those conformations of ortho xylene in which the coupled protons are in close proximity yield computed values plausibly attributable to "direct" and/or "through-space" mechanisms. The preferred conformation of the methyl group in toluene is predicted to have a C—H bond eclipsing the plane of the aromatic ring and the calculated barriers to rotation of 0.013 kcal/mol in toluene and of 0.014 kcal/mol in p-fluorotoluene are in quantitative accord with microwave data.
Coupling of Amino Acids and Amino Sugars with Cyanuric Chloride (2,4,6-Trichloro-s-triazine)
Authors: Chaudhari A. S. , Bishop C. T.
Published: May 2006

2,4,6-Trichloro-s-triazine (cyanuric chloride) has been used to couple glycine ethyl ester with seven carbohydrate derivatives that contain amino groups. The reactions proceed in high yield under mild conditions. The compounds serve as models for the coupling of carbohydrates to proteins by well-defined linkages through amino groups.
Ceric Ammonium Nitrate Oxidation of Cyclic Ketones
Authors: Soucy P. , Ho Tse-Lok , Deslongchamps P.
Published: May 2006

Ceric ammonium nitrate oxidation of cyclohexanone, cyclopentanone, and norbornanone gives nitrato-carboxylic acids, oxidation of adamantanone and adamantan-2-ol gives the lactone 14.
A Regiospecific Construction of α-Haloketones by the Reaction of Enol Borinates with N-Bromo- and N-Chlorosuccinimide. A Convenient Method for Converting Olefins into α-Haloketones and Esters
Authors: Hooz John , Bridson John N.
Published: May 2006

α-Bromo- and α-chloroketones may be synthesized in a regiospecific manner in high yields by treatment of an enol borinate with N-bromo- or N-chlorosuccinimide. This method preassembles the carbon skeleton of the ketone, and thereby avoids the problems (isomer formation, polyhalogenation) inherent in other methods. α-Haloesters are also easily synthesized by this procedure.
Heterogeneous Interactions of Methylamines on porous Adsorbents Part II. Interactions on Silica–Alumina and Silica Gel Surfaces of Di- and Tri-methylamine in the Region of their Boiling Points
Authors: Cook W. G. , Ross R. A.
Published: May 2006

The adsorption of di- and tri-methylamine has been studied at 280 and 276°K, respectively, on a range of silica gels and on silica–alumina. Adsorption–desorption isotherms and isothermal calorimetric heats of adsorption were measured. Heats of adsorption for di-methylamine on silica gel varied from 29.0 kcal/mol at θ = 0.05 to 12.0 kcal/mol at monolayer completion, while for silica–alumina the heats fell from 31.4 to 9.0 kcal/mol between these same values of surface coverage. For tri-methylamine on silica gel, heats fell from 21.0, θ = 0.05, to 10.3 kcal/mol, θ = 1.00, while heats of 21.4 and 9.9 kcal/mol, respectively, were found at these same surface coverages on silica–alumina. The values of the heats of adsorption are discussed in terms of interactions in the adsorbed layer which are believed to be influenced by the pore sizes in the adsorbent and by the basicity of the amine molecules.
The Effect of Temperature and Solvent upon the Addition of 4-Chlorobenzenesulfenyl Chloride to cis- and trans-1-Phenylpropene
Authors: Schmid George H. , Csizmadia Valeria M.
Published: May 2006

The effect of temperature upon the product composition of the addition of 4-chlorobenzenesulfenyl chloride to cis- and trans-1-phenylpropene in 1,1,2,2-tetrachloroethane has been studied. The kinetically controlled product in both cases is the adduct with Markownikoff orientation while the thermodynamically controlled product is the one with the anti-Markownikoff orientation. Kinetic and thermodynamic parameters have been determined for the isomerization of the threo as well as the erythro adducts. The effect of different solvents on the product composition has been studied at 25°. The regioselectivity towards Markownikoff product parallels the increasing acidity and anion solvating ability of the solvent.
Determination of D[(CH3)3Pb—CH3] by the Toluene Carrier Method
Authors: Gilroy K. M. , Price S. J. , Webster N. J.
Published: May 2006

The pyrolysis of tetramethyl lead has been studied in a toluene carrier flow system over the temperature range 671–753 °K (contact times 0.72–1.67 s, 3–77% decomposition). The reaction was followed by measuring the amount of methane, ethane, and ethylbenzene formed. Comparison of the extent of reaction based on product analysis and on alkyl recovery indicates that approximately four methyl radicals are released for each molecule undergoing reaction 1.[Formula: see text]The method of least squares gives k1 = 5.0 × 1014 exp (−49 400/RT) sB1 with an estimated uncertainty of ± 1 000 cal mol−1 in E1. Under the conditions used E1 should be a reasonable measure of D[(CH3)3Pb—CH3].
Conversion of Nonlinear Shift Reagent Plots to Linear Plots
Authors: ApSimon J. W. , Beierbeck H. , Fruchier A.
Published: May 2006

A method is presented for converting partially or completely nonlinear shift reagent plots to perfectly linear plots, from which highly accurate intercepts and slope ratios can be obtained even for nuclei, whose signals can only be observed in the nonlinear region of the original plots.
Vapor Phase Raman Transitions in the CH2 Scissoring Region and the Ring Puckering Vibration of Trimethylene Oxide and some Deuterated Analogs
Authors: Wieser H. , Danyluk M. , Kiefer W. , Bernstein H. J.
Published: May 2006

The vapor phase Raman spectra of trimethylene oxide (TMO) and two of its deuterated analogs (α-d2 and β-d2) each show one sharp line on a weak, broad, and unresolved band in the CH2 scissoring region. Under high resolution these lines are resolved into several components. They are assigned to the fundamentals of the scissoring mode of α-CH2 (in-phase, A1 symmetry, in the case of the normal and β-d2 compound) and overlapping bands resulting from interaction with the low frequency puckering vibration. The agreement between Raman and i.r. data is excellent and the assignments are entirely consistent. Raman lines corresponding to the out-of-phase combination (B2 symmetry) of the α-CH2 scissoring vibration and the scissoring mode of the β-CH2 group (in normal, α-d2 and α,α′-d4 TMO) cannot be resolved.
Quantitative Investigation of the Ozonolysis Reaction. XVII. Relative Reaction Rates for the Ozone Attack on Phenylethylenes
Authors: Klutsch G. , Fliszár S.
Published: May 2006

The relative rate constants for the reaction of ozone with a variety of ring-substituted phenylethylenes in CCl4 solution obey Hammett's equation [Formula: see text] with σ ≈ −0.9. Non-conjugating β-substituents affect the rate constants in Taft's σ* order [Formula: see text] These results illustrate the electrophilic mode of attack of ozone.
Conductances, Densities, and Viscosities of Solutions of Sodium Nitrate in Water and in Dioxane–Water, at 25 °C
Authors: Kartzmark Elinor M.
Published: May 2006

The conductances, densities, and viscosities of solutions of sodium nitrate in water and in 20, 40, 60, 70, and 80 wt. % dioxane–water have been measured at 25 °C, from [Formula: see text] to saturation. The data have been fitted to the Fuoss–Onsager equation, yielding values of Λ0, å, and KA; and in concentrated solutions to the equations of Wishaw–Stokes and Gellings. Apparent molar volumes have been calculated.No appreciable ion association is apparent in solutions whose dioxane content is less than 60% by weight. Passing from water to 80% dioxane, the values of å obtained from the Fuoss–Onsager equation increased from 2.74 to 7.60 Å, a sharp increase occurring beyond 60%.
The Synthesis of some α-Cyclopropylcarbonyl Glycopyranosides
Authors: Fraser-Reid Bert , Carthy Bernard J.
Published: May 2006

The syntheses of three α-cyclopropylcarbonyl compounds of carbohydrate origin, 1, 2, 3, are described. The cyclopropyl carboxaldehyde 1 was obtained from the corresponding carbinol by manganese dioxide oxidation of the primary alcohol. However, the secondary cyclopropyl alcohol in 8 did not respond to manganese dioxide and its oxidation (in the tritylated derivative (14), to the cyclopropyl ketone, 2, had to be achieved by ruthenium tetroxide. The sequence leading to 2 (via 8) began with ethyl 4,6-di-O-acetyl-2,3-dideoxy-α-D-erythro-hex-2-enopyranoside 11, which added methylene to give the α-D-allo configuration with the cyclopropane ring syn to the glycosidic ethoxy group. The diastereomeric tritylated cyclopropyl ketone 3, possessing the cyclopropyl ring anti to the ethoxy group, resulted from cyclopropanation of the αβ-un-saturated ketone, 15. In the latter case, the acetoxy group apparently provides greater directing influence to the incoming methylene than does the allylic ethoxy group.
Ammine Complexes of Osnium(II)
Authors: Allen A. D. , Stevens J. R.
Published: May 2006

Several ammine complexes of osmium(II) containing one or two π-acceptor ligands have been prepared. They have been characterized by analytical techniques and their infrared and electronic spectra have been recorded and assignments proposed. Comparison with similar ruthenium(II) complexes has been made when possible.
Acetate-catalyzed Bromination and Exchange Reactions of 2-Butanone
Authors: Thorpe J. W. , Warkentin J.
Published: May 2006

Products from bromination of 2-butanone in an aqueous acetate buffer were studied in order to compare the regiochemistry of monobromination with that of deuterium exchange. The good agreement found suggests that direct reaction of Br2 with unenolized ketone, for which there have been claims in the literature recently, is unimportant or absent under the conditions of the experiments.
Effects of Bromine Substituents on Rates of Acetate-promoted Enolization of Ketones
Authors: Cox R. A. , Warkentin J.
Published: May 2006

Effects of bromine substituents on rates of acetate-catalyzed bromination of ketones are reported. Approximate polar contributions to the rates were obtained, based on the approximation that the steric effects of bromine and methyl are identical. Such polar substituent effects are quite large at the α′-position of an α-bromo ketone, leading to the conclusion that the carbonyl group is much better than the methylene group in transmitting polar effects.Rate enhancements caused by α-bromine substituents are largely entropic in origin and rates correlate well with ionization constants of α-bromo acids. These results are interpreted as indicative of an enolate-like transition state for acetate-catalyzed enolization.
A Total Synthesis of Cadin-4, 10(15)-dien-3α-ol: Structure of Khusinol
Authors: Kelly R. B. , Eber J.
Published: May 2006

A total synthesis of cadin-4,10(15)diene-3α-ol, one of the structures proposed for khusinol, is described. Neither this compound nor its C3-epimer was identical with khusinol.
Solvolysis of Substituted Nortricyclanes and Norbornenes at 250°
Authors: Werstiuk Nick H. , Kadai T.
Published: May 2006

Solvolysis of nortricyclyl bromide (1a), nortricyclyl chloride (1b), nortricyclanol (1c), and 5- and 7-norbornenols (2b, 7) and exo-2,3-epoxybicyclo[2.2.1]heptane (11) in 10% v/v acetic acid – water at 250° yields 2-(cyclopentene)acetaldehyde (3), 3-(cyclopentene)acetaldehyde (4), 3-(cyclohexene)carboxaldehyde (5), norcamphor (6), and norbornanediols. In each case the diol concentration builds up then decreases as the conversion to 3, 4, 5, and 6 occurs. When the substrates 1a, b, and c, 2b, 7, 10a, and 11 are solvolyzed in deuterated medium, deuterium other than α to the carbornyl group is incorporated into the aldehydes and norcamphor.
The Infrared Spectrum of Ethylene Oxide Clathrate Hydrate between 360 and 20 cm−1, at 100 °K
Authors: Bertie J. E. , Othen D. A.
Published: May 2006

The infrared spectra of authenticated samples of ethylene oxide hydrate and deuterate at 100 °K have been measured between 360 and 20 cm−1. The spectra confirm that the water molecules are orientationally-disordered and reorient slowly compared to far-infrared frequencies. An empirical correlation is suggested between the frequencies of strong absorption and the number of non-equivalent hydrogen bonds, their length and distribution. The contribution to the spectrum by the ethylene oxide intermolecular vibrations is discussed.
Orientational Dependance of Vicinal and Geminal 13C–1H Coupling
Authors: Schwarcz J. A. , Perlin A. S.
Published: May 2006

The effect of changes in the relative orientation of vicinal and geminal 13C and 1H nuclei, and in the disposition of adjacent substituents, on coupling between these nuclei has been examined with a variety of 13C-labelled carbohydrates. Compounds synthesized for this purpose include derivatives of D-glucose-1- and -6-13C and L-idose-6-13C, and related lactones, and the measurements have been made with p.m.r. spectra of these compounds. Vicinal 13C-1H coupling, both through C—C and C—O bonds shows an orientational dependance analogous to that for protons: i.e., dihedral angles of 60–100° are associated with smaller coupling (0–3 Hz) than angles of 140–180° (4.5–5.5 Hz); sp2 carbon produces splittings of almost twice these values. The observed spacing is smaller when an oxygen atom is in the plane of the coupling pathway than when out of plane, both for vicinal and geminal 13C–1H interactions, and the presence of an extra oxygen also may have a notable impact on the geminal interaction. A study of rotational isomerism in these compounds indicates that the characteristics of coupling between 13C and 1H nuclei may fruitfully be compared with those of H–H coupling in the analysis of such dynamic systems.
The 125Te Mössbauer Absorption Spectra of the Thiourea, Ethylenethiourea, and Tetramethylthiourea Derivatives of Tellurium(II) and Tellurium(IV)
Authors: Cheyne B. M. , Jones C. H. W. , Vasudev P.
Published: May 2006

The 125Te Mössbauer spectra of a number of Te(II) and Te(IV) complexes of thiourea and related derivatives have been measured. The isomer shifts and quadrupole splittings for several of the compounds are interpreted in terms of a bonding scheme utilizing three-center, two-electron bonds in which the tellurium 5p orbitals participate. The 129I Mössbauer spectrum of trans-TeEtu2129I2 is reported and the isomer shift and quadrupole splitting are shown to be consistent with the proposal that the iodine uses only a 5p orbital in bonding to the tellurium.
The Oxidation of Organic Compounds by Sodium Ruthenate
Authors: Lee Donald G. , Hall David T. , Cleland James H.
Published: May 2006

The preparation of sodium ruthenate and its use as an oxidant for a variety of organic compounds is decribed.
Photooxidation and Decarboxylation of Tyrosine Studied by E.P.R. and C.I.D.N.P. Techniques
Authors: Tomkiewicz Micha , McAlpine Robert D. , Cocivera Michael
Published: May 2006

The photooxidation of deoxygenated solutions of tyrosine in water at pH 8.5–12.6 has been studied at room temperature using e.p.r. spectroscopy. By means of e.p.r., four radicals were detected during irradiation with the full spectrum of a Hg–Xe arc lamp. These were identified as the tyrosyl radical, [Formula: see text] and two radicals derived from dopa. A tentative mechanism suggested for [Formula: see text] formation involves the reaction of tyrosine with the hydrated electron, which has been ejected from another tyrosine molecule in one of its excited electronic states. A mechanism similar to the one proposed for the photooxidation of phenol has been suggested for the formation of the radicals derived from dopa. Support for this mechanism is provided by the observation of proton nuclear spin polarization during irradiation.
A New Photochemical Reaction of Unconjugated Thioketones
Authors: Worman James J. , Shen Mason , Nichols Patrick C.
Published: May 2006

Tetramethyl-3-thio-1,3-cyclobutanedione (1) and tetramethyl-1,3-cyclobutanedithione (6) react with oxygen in the presence of light to yield tetramethyl-1,3-cyclobutanedione (2). A mechanism involving singlet oxygen is suggested. 1,3-Diphenyl-2-propanethione (3) undergoes accelerated dimerization in the presence of visible radiation to yield tetrabenzyl-1,3-dithietane (4).
Crystal Structure of 1-Cyanotetracyclo[3.3.1.13,7.03,7]decane
Authors: Gibbons Cyril S. , Trotter James
Published: May 2006

Crystals of 1-cyanotetracyclo[3.3.13,7.03,7]decane, C11H13N, are monoclinic, a = 6.442(2), b = 11.739(2), c = 11.965(4) Å, β = 98.14(9)°, Z = 4, space group P21/c. The structure was determined with CuKα scintillation counter data by direct methods, and refined by full-matrix least-squares techniques to R 0.048 for 690 observed reflexions. C(3) and C(7) have all four bonds directed to one side of the atoms, and the central bond distance is 1.643 Å. Other bond lengths and angles are normal.
Pressure Dependence of Product Yields in the Direct Photolysis of Methanol Vapor at 1849°Å
Authors: Herasymowych O. Sonia , Knight Arthur R.
Published: May 2006

Hydrogen and methane yields from the 1849 Å photolysis of methanol vapor in an all-quartz system have been investigated as a function of exposure time and pressure of CH3OH and added CO2.Product yields are decreased by the inert addend, and by the substrate itself at high pressures, in contrast to the collision-induced quantum yield enhancement reported to be occurring in this system.
Conformations of Bridged Diphenyls. IV. Diphenyl Ether Conformations and Proton Chemical Shifts
Authors: Bergman J. J. , Griffith E. A. H. , Robertson B. E. , Chandler W. D.
Published: May 2006

The conformationally dependent chemical shifts for the ring protons of some diphenyl ethers can be explained approximately by the ring-current model for benzene magnetic anisotropy. Although the model underestimates the shielding in the region above the plane of the ring it is the best of the models investigated for this purpose.
The Radiochemistry of Organoiron Compounds. III. Fe(CO)5–Cyclopentadiene Solutions
Authors: Kanellakopulos-Drossopulos W. , Wiles D. R.
Published: May 2006

Nucleogenesis of 59Fe gives iron atoms which react with monomeric cyclopentadiene to produce 59FeCp2, either in liquid or solid solutions, but do not react appreciably with dimeric cyclopentadiene. This is taken as showing that local thermal effects of the nuclear reactions are ineffective in causing the dissociation (C5H6)2 → 2C5H6. The concentration dependence of the yield of 59FeCp2 indicates that the 59Fe atom reacts primarily at its point of genesis rather than after diffusion.
Double Layer Structure at the Mercury/Acetonitrile Interface
Authors: Fawcett W. R. , Loutfy R. O.
Published: May 2006

The results of a study of double layer capacity at the mercury/acetonitrile interface in the presence of alkali metal and tetraalkylammonium perchlorates are presented. It is shown that the Li+, Na+, tetraethylammonium, and perchlorate ions are not significantly adsorbed over most of the polarizable range of the electrode, whereas the K+ and Cs+ ions are adsorbed at more cathodic potentials. Inner layer capacity data are presented and discussed in terms of the specific effects of ions on interfacial structure.
Preparation and Characterization of Pseudohalogeno(methyl)germanes and Related Compounds
Authors: Drake J. E. , Hemmings R. T.
Published: May 2006

Synthetic routes to the series of pseudohalogeno(methyl)germanes, MeGeH2Ps and MeGePs3 (Ps = N3, CN, NCO, NCS), and the related compounds MeGeH2OAc and Ge(N3)4 are discussed. The compounds are characterized by their molecular weights, mass spectra, 1H n.m.r. spectra and cleavage reactions. Their i.r. and Raman spectra are assigned as further confirmation of their structures.
Reaction of Oxygen Atoms, O(3P), with Ethylene in Liquid Nitrogen Solution
Authors: Hirokami Shun-Ichi , Cvetanović R. J.
Published: May 2006

The reaction of ground-state oxygen atoms, O(3P), with ethylene and ethylene-d4 in liquid nitrogen solution at 77° K has been studied. The major and perhaps the exclusive products are ethylene oxide and acetaldehyde. The ratio of acetaldehyde to ethylene oxide is 1.2 ± 0.1 for ethylene and 0.91 ± 0.09 for ethylene-d4. Much smaller amounts of formaldehyde and trace quantities of cyclopropane are also observed.The effect of the concentration of ethylene on the quantum yields of addition products was measured. A limiting quantum yield of oxygen atoms scavenged by ethylene to form the addition products was 0.12 + 0.01. The low quantum yield suggests an appreciable cage recombination of the ground-state oxygen atoms with the trace amounts of molecular oxygen present. The effect of the concentration of added oxygen on the product yields and the relative rate constant for the addition of O(3P) to molecular oxygen and to ethylene were determined. The ratio [Formula: see text] is 6.0 ± 1.0 and the relative rate constant for the addition of O(3P) to ethylene and to ethylene-d4, [Formula: see text], is 2.0 ± 0.1.The type of products formed and the isotope effects observed are discussed in terms of the mechanism of addition of O(3P) atoms to ethylene.
Base-catalyzed Degradations of Carbohydrates. IV. Formation of 2,3-Anhydro-2-methoxy-α-D-allopyranose Derivatives from 3-Deoxy-D-erythro-hex-2-enopyranoses
Authors: Aspinall G. O. , King R. R.
Published: May 2006

1,4,6-Tri-O-acetyl-3-deoxy-2-O-methyl-α-D-erythro-hex-2-enopyranose (4) reacts with m-chloroperbenzoic acid to give the epoxide, 1,4,6-tri-O-acetyl-2,3-anhydro-2-methoxy-α-D-allopyranose (6), as the major product together with the perester, 4,6-di-O-acetyl-1,2-O-(1′-m-chloroperbenzoyloxy-ethylidene)-2-methoxy-α-D-glucopyranose (5), as a minor product. The structures of these novel compounds have been assigned on the basis of spectroscopic data and of transformations (i) to kojic acid diacetate and (ii) by oxidative degradations to substituted aldopentonolactones. Further examination of the products of the reaction of 1-O-acetyl-3-deoxy-2,4,6-tri-O-methyl-α-D-erythro-hex-2-enopyranose (1) with m-chloroperbenzoic acid has shown that the epoxide, 1-O-acetyl-2,3-anhydro-2-methoxy-4,6-di-O-methyl-α-D-allopyranose (15), is formed in addition to the previously characterized perester 2.
X-Radiolysis Ion Yields and Electron Ranges in Liquid Xenon, Krypton, and Argon: Effect of Electric Field Strength
Authors: Robinson Maurice G. , Freeman Gordon R.
Published: May 2006

X-Radiolysis ion yields were measured at electric fields between 1 and 60 kV/cm in argon at 87 °K, krypton at 148 °K, and xenon at 183 °K. The results were analyzed according to a theoretical model to obtain the total ion yields Gtot,the free ion yields at zero field strength Gfi0 and the most probable penetration ranges b of the secondary electrons in the liquids. The respective values were: Ar, 7.3, 2.9, 1330 Å; Kr, 13.0, 5.8, 880 Å; Xe, 13.7, 7.0, 720 Å. The total ionization yields in these substances are greater in the liquid than in the gas phase, probably due to smaller ionization potentials in the condensed phase (polarization energy effect). Field dependent electron mobilities are also reported.
Kinetics of Quasifree Electron Reactions in the Liquids Methane, Krypton, and Xenon
Authors: Robinson Maurice G. , Freeman Gordon R.
Published: May 2006

The encounter efficiency of e− + N2O → N2O in the liquids methane, krypton, and xenon at 183 °K is f ≈ 105. The parameter β, for the nonhomogeneous kinetics of reactions in γ radiolysis spurs in the liquids, has values similar to those (1013–1014 V/cm2) obtained earlier for liquids such as cyclohexane, methanol, and water at 298 °K, in which f is approximately unity. Previous results for nitrous oxide in neopentane at 296 °K have been reinterpreted to obtain f ≈ 10−2. For solvents in which the electron mobility is very high (~103 cm2/Vs) the value of f is low. As the electron mobility decreases f increases to a maximum of unity.
13C Nuclear Magnetic Resonance Spectra of Bridged 10π-Electron Systems. The Extent of Electron Delocalization
Authors: Kemp-Jones A. V. , Jones Alan J. , Sakai M. , Beeman C. P. , Masamune S.
Published: May 2006

The 13C n.m.r. spectrum of the cation 4 suggests the presence of considerable 1,7-bonding, indicating that it should be described as a substituted homotropylium cation rather than a monocyclic 10π-electron system. The intra-annular carbon atoms of 3 and 4 do not show a significant upfield shift due to the ring current. Explanations are offered.
Pressure Effects upon the Rates of Aquation of Halopentaamminechromium(III) Ions: Evidence for an Associative Mechanism
Authors: Guastalla G. , Swaddle T. W.
Published: May 2006

For the replacement of X− by H2O in Cr(NH3)5X2+, ΔVo* (the value of the volume of activation ΔV* at zero pressure) at 25.0° in 0.1 m NH4ClO4 is −10.8, −10.2, and − 9.4 cm3 mol−1 respectively for X− = Cl−, Br−, and I−, while ΔV, the molar volume of reaction, is −8.4, −7.2 and −6.0 cm3 mol−1. The pressure-dependence of ΔV* can be expressed in terms of the number x of water-molecules which are electrostricted as the systems go from ground-state to transition-state; for X− = Cl−, Br−, and I−, x = 1.9, 2.0, and 1.7. These data, combined with ΔV* = −5.8 cm3 mol−1 for the aquo-exchange of Cr(NH3)5OH23+, indicate an associative mechanism for these reactions, as does the contrast with ΔV0* data for the formally analogous, but dissociatively-activated, reactions of Co(NH3)5X(3−n)+.
6,8,8-Trimethyl-6-(o-methylthiobenzoyl)-4-thia-benzocyclooctenone. A Novel Product from the Attempted Base-catalyzed Methylation of 3-Methylthiochroman-4-one
Authors: Still Ian W. J. , Chauhan Mohinder S. , Thomas M. Thomas
Published: May 2006

The structure of the unusual eight-membered cyclic ketone 3 obtained on treatment of 3-methylthiochroman-4-one with methyl iodide in the presence of potassium t-butoxide has been assigned on the basis of n.m.r. (13C and 1H), i.r., and mass spectrometric evidence. A mechanism has been proposed to account for the formation of both abnormal and expected methylation products from 3-methylthiochroman-4-one under varying conditions.
The Bimolecular Self-reactions of Secondary Peroxy Radicals. Product Studies
Authors: Lindsay D. , Howard J. A. , Horswill E. C. , Iton L. , Ingold K. U. , Cobbley T. , Ll A.
Published: May 2006

The principal products formed from 1-ethoxyethyl hydroperoxide and 1,2-diphenylethyl hydroperoxide on oxidation with reagents that are presumed to generate the corresponding sec-alkylperoxy radicals (Ce(IV), tert-butoxy, and Ag2O) have been identified. The products formed when the corresponding alkoxy radicals are generated in pairs have also been identified. It is concluded that the Russell (1) concerted cyclic mechanism in which tetroxide decomposed to molecular products is not the exclusive route for the bimolecular self-reaction of sec-alkylperoxy radicals. It is suggested that there is also a second tetroxide decomposition process which yields radical products. The second process may yield "free" alkoxy radicals or it may, perhaps, yield the products of β-scission of the alkoxy radicals in a step concerted with O—O homolysis of the tetroxide. The relative importance of tetroxide decomposition to molecular and to radical products will depend on the structure of the alkyl groups, the temperature and, perhaps, the solvent.
The Formation and Decay of the Paramagnetic Species Formed on the Surface of Al2O3–MoO3 with Anthracene/Benzene Solution
Authors: Ueda Hisashi , Todo Naoyuki
Published: May 2006

MoO3 supported on alumina in a flow-through type sample tube was fixed in an e.s.r. cavity and anthracene solutions in benzene were passed through it at 20 °C. Three paramagnetic species were observed. One was Mo5+, one was the anthracene cation R+, and the remaining one was R+O*2− previously reported. Formation of R+ and R+O*2− was complete within a few minutes after the contact of the solution after which the decay of R+ became apparent. R+ disappeared in a pseudo-first order reaction which actually was a second order reaction with the water dissolved in the solution. The rate constant for the reaction, R+ + H2O → diamagnetic products, was 0.341 mol−1 s−1. R+O*2− was completely stable during the measurement and even after draining the solvent or after drying the oxide particles with N2 gas. It was concluded that Mo5+ was formed from two R+ and H2O molecules. The time dependence of the concentration of R+ was found to be [R+] = [R+]0 exp(−kt) and that of Mo5+, [Mo5+] = [Mo5+]∞ (1 − exp (–kt)) where the subscripts zero and infinity indicate the time t = 0 and t = ∞ respectively. The present results seem to indicate that the more important paramagnetic species which influences the catalytic processes is not the cation R+ but the complex ion R+O2−.
Iron Carbonyl Complexes of the Diastereomers of cis-(C6H5)(CH3)AsC(CF3)=C(CF3)As(CH3)(C6H5)
Authors: Cullen W. R. , Mihichuk L.
Published: May 2006

The reaction of CF3≡CCF3 with (C6H5)(CH3)As—As(CH3)(C6H5) gave both cis- and trans-(C6H5)(CH3)AsC(CF3)=C(CF3)As(CH3)(C6H5), (L—L), in nearly equal amounts. When hexafluoroacetone is used as solvent the cis-isomer predominates (88%). The two diastereomers of the cis-adduct were isolated and reacted with Fe(CO)5 to afford (L—L)Fe(CO)3 and (L—L)Fe2(CO)6. Two of the three possible geometric isomers of the latter were obtained and their properties allowed assignment of the configuration of the starting ligands. Minor amounts of the symmetric and asymmetric forms of [Fe(CO)3As(CH3)(C6H5)]2 were also obtained through loss of fluorocarbon.
Trends in the Spectrochemical Series and 31P Chemical Shifts of Five-coordinated Cyclopentadienylnickel(II) Complexes
Authors: Thomson J. , Baird M. C.
Published: May 2006

The electronic spectra and 31P n.m.r. spectra of the complexes π-C5H5NiPPh3X (X = Cl, Br, I, NCO, NCS, NO2, CN, SnCl3, SnPh3, PbPh3, alkyl, and aryl) have been obtained and interpreted. The "common" anions form a spectrochemical series which is identical with that reported for many octahedral systems, while the carbon, tin, and lead donors lie relatively high in the series. Currently accepted theory for the chemical shifts of ligand donor atoms fails to satisfactorily rationalize the 31P chemical shifts.
Crystal and Molecular Structure of B,B- Diphenylboroxazolidine (2-Aminoethyl Diphenylborinate),
Authors: Rettig Steven J. , Trotter James
Published: May 2006

Crystals of the title compound are monoclinic, a = 13.840(1), b = 8.9169(5), c = 10.170(1) Å, β = 98.85(1)°, Z = 4, space group P21/n. The structure was determined by direct methods, and refined by electron-density and full-matrix least-squares procedures to R 0.041 for 1458 observed reflections. The five-membered boroxazolidine ring is in the half-chair conformation. Bond angles in the ring range from 99.7° for OBN to 110.1° for BOC. Bond lengths are as follows: mean B—C, 1.611(2), B—N, 1.653(3), B—O, 1.484(3), C—N, 1.485(3), C—O, 1.413(3), mean C—C (aromatic), 1.383(11), and C—C, 1.505(4) Å. The structure consists of discrete molecules linked by O…H—N hydrogen bonds (2.874(2) Å) to form continuous spirals about the 21 axes.
Rearrangement Studies with 14C. XXXVIII. Isotopic Scrambling in the Synthesis of Labeled 2-Phenylethyl Triflate
Authors: Lee C. C. , Unger D.
Published: May 2006

2-Phenylethyl triflate (1-OTf) was synthesized by the reaction of AgOTf with 2-phenylethyl iodide (1-I) in cyclohexane as solvent. However, when 1-14C-2-phenylethyl iodide (1-I-1-14C) was used as a reactant, the resulting 1-OTf-14C showed an essentially complete scrambling of the 14C-label over the C-1 and -2 positions. Similar reactions of 1-I-1-14C with AgOTs and with AgOAc gave 1-OTs-14C and 1-OAc-14C with, respectively, about 49 and 11% rearrangement of the label from C-1 and -2.
Fluoroalicyclic Derivatives of Cobalt Carbonyl
Authors: Cullen William R. , Jull A. J. T.
Published: May 2006

The compounds [Formula: see text] are obtained by reacting the metal carbonyl anion with the appropriate 1,2-dichloro olefin. Similar compounds are not isolated following treatment of cobalt carbonyls with [Formula: see text]. The new bridged complex [Formula: see text] is described.
Ring–Chain Tautomerism of 5-Oxo-3,5-seco-A-norcholestan-3-ol
Authors: Edward John T. , Kaufman Morris , Wojtowski Richard K. , Wheeler Desmond M. S. , Barrett Thomas M.
Published: May 2006

5-Oxo-3,5-seco-A-norcholestan-3-ol (4) was prepared in four steps from Windaus' keto-acid (1; R = H), and found to exist almost completely in the tautomeric hemiketal form 5. With ethanol and a trace of acid this affords the ethyl ketals 6a, 6b; under equilibrium conditions the ratio of 6a:6b is about 4:1.
Bimolecular Reactions of Trapped Ions. VI. Ion–Molecule Reactions Involving CH5+ and C2H5+
Authors: Blair A. S. , Harrison A. G.
Published: May 2006

The ion–molecule reactions in mixtures of methane with the polar molecules dimethyl-d6 ether, ethylene-d4 oxide, acetaldehyde-d4, acetone, and acetonitrile have been studied using the trapped-ion technique. The CH5+ and C2H5+ ions produced by ion–molecule reactions in methane react rapidly (predominantly by proton transfer) with the polar molecules; the rate coefficients range from 1.98 × 10−9 cm3 molecule−1 s−1 (C2H5+ + C2D4O) to 5.26 × 10−9 cm3 molecule−1 s−1 (CH5+ + (CH3)2CO). The rate coefficients are much larger than those predicted from ion – induced dipole interactions only indicating that ion–dipole interactions play a large role in the collision process.Rate coefficients for reaction of CH3+ and CH4+ with the polar molecules also have been measured. Most of these also are larger than predicted from ion – induced dipole interactions indicating in this case as well substantial effects due to ion–dipole interactions.