bluuebunny/crossref_metadata_2025 huggingface dataset:
On the deexcitation of the singlet excited oxygen atoms
Authors: Yamazaki Hideo
Published: May 2006

The relative efficiency of a number of gases for the collisional deexcitation or chemical reaction with the singlet excited oxygen atoms O(1D2) was studied by a competitive technique. Excited oxygen atoms were produced by the photolysis of nitrous oxide at 2139 Å and of ozone at 3132 Å. The order of the relative efficiency of the foreign gases is [Formula: see text] in the photolysis of nitrous oxide and [Formula: see text] in the case of ozone. These trends are consistent with the previous results.
Stereoselective synthesis of (±)epihinesol (agarospirol)
Authors: Mongrain M. , Lafontaine J. , Bélanger A. , Deslongchamps P.
Published: May 2006

An efficient stereoselective synthesis of (±)epihinesol (1) (agarospirol) is described.
The kinetics of hydration of tricalcium silicate
Authors: McCurdy K. G. , Erno B. P.
Published: May 2006

An investigation has been made of the kinetics of hydration of tricalcium silicate at several temperatures in a large excess of water in the presence of various added ions. The rate data have been interpreted by a reaction mechanism which involves: (a) the first order hydration of tricalcium silicate to form an intermediate product, 1.5CaO•SiO2, which can react by two pathways, (b) the direct first order decomposition of intermediate, 1.5CaO•SiO2, to form lime and silica or (b′) complexing of intermediate with silica and subsequent decomposition to form lime and silica. This reaction mechanism predicts the rate of production of base during the hydration. The effect of various added ions is interpreted in terms of the proposed mechanism.Rate constants and activation energies for the various steps in the proposed mechanism are reported.
Ionic reactions occurring in the irradiation of carbon dioxide – oxygen mixtures at very high dose rates
Authors: Willis Clive , Bindner P. E.
Published: May 2006

Ozone yields have been measured in CO2–O2 mixtures irradiated with single pulses from a Febetron 705 at a dose rate of 1026 eV g−1 s−1. Low concentrations of carbon dioxide in oxygen rapidly reduce the yield from G(O3) = 12.8 to G(O3) ≈ 9. At 300 Torr total pressure, as the oxygen concentration is reduced, the ozone yield decreases from this yield of G(O3) ≈ 9 to an extrapolated yield, at zero oxygen, of close to G(O3) = 7.8. Changes of yields with composition are explained in terms of ionic reactions, the main neutralization process being[Formula: see text]At 700–1500 Torr total pressure, the ozone yields are lower than that at 300 Torr. It is proposed that clustering of the ionic species affects the products of the neutralization reaction.Sulfur hexafluoride suppresses the dissociative neutralization reaction and ozone yields from mixtures containing 1.5–2% SF6 are those predicted from direct neutral dissociation processes in the pure gases.Computer calculations are used to compare the experimental results to the proposed mechanism and, in general, a good fit is obtained.
The rubidium chloride – sodium chloride phase diagram
Authors: Pelton A. D. , Flengas S. N.
Published: May 2006

The phase diagram of the RbCl–NaCl system has been measured by the method of cooling curves. By combining these data with available thermochemical data for the system, the integral molar excess free energy of mixing at 800 °C has been calculated as ΔGE = −632XRbClXNaCl cal/mole; and the integral molar excess entropy of mixing has been calculated as ΔSE = −0.208XRbClXNaCl cal/°K mole. Estimated precisions are ±50 cal for ΔGE and ±0.05 cal/°K mole for ΔSE at XRbCl = XNaCl = 0.5.
Isolation and structure of monochaetin, a metabolite of the fungus Monochaetiacompta
Authors: Spencer H. , Mo Y. K. , Tertzakian G. , Slater G. P. , Haskins R. H. , Nesbitt L. R.
Published: May 2006

A new metabolite has been isolated from the fungus Monochaetiacompta. The properties and reactions of the metabolite suggest that it is 6,8a-dihydro-4-acetyl-8-methyl-6-oxo-7(3-methyl-2-oxo)-pentyl-1 H-2-benzopyran-1-one (2a).
Silylcarbonium ions from the reaction of silylcarbinols with boron trifluoride
Authors: Brook A. G. , Pannell K. H.
Published: May 2006

The behavior of silylcarbonium ions, Si—C+, generated from various types of α-silylcarbinol with boron trifluoride under a variety of conditions of temperature and solvent has been examined. Four distinct types of reaction have been observed, depending on the conditions and the structure of the carbinol. These are: 1,2-migration of aryl groups from silicon to carbon, yielding a fluorosilane; Friedel–Crafts substitution of the carbonium ion on an aromatic substrate; elimination of the elements of water to give a vinylsilane; and isomerization to the β-silylcarbonium ion by hydrogen migration, followed by elimination of the silyl group to give a simple fluorosilane and an alkene (i.e. a β-elimination). Factors affecting the partitioning between these pathways are discussed.
Solvolytic reactivity of bridgehead substituted tricyclo[4.4.0.03,8]decanes (twistanes)
Authors: Bingham R. C. , Schleyer P. von R. , Lambert Y. , Deslongchamps P.
Published: May 2006

Several bridgehead substituted twistanes (tricyclo[4.4.0.03,8]decanes) have been prepared and their solvolysis rates determined. 1-Twistyl derivatives react only slightly faster than the corresponding bicyclo-[2.2.2]octyl derivatives and about 103 more slowly than 1-adamantyl derivatives. Although the ground states of all three of these molecules are essentially free from angle strain, they differ in the degree of nonbonded interactions, which is the main reason for the decrease in 1-twistyl and 1-bicyclo [2.2.2]octyl reactivity.
Hydrophobic folding of maltose in aqueous solution
Authors: Neal J. L. , Goring D. A. I.
Published: May 2006

The apparent specific thermal expansibilities of glucose, cellobiose, and maltose were compared to show that the maltose molecule folds in solution and undergoes intramolecular hydrophobic bonding.
Kinetics of the exchange reaction of dimethylarsenic deuteride with diethylarsine
Authors: Cullen W. R. , Leeder W. R.
Published: May 2006

The exchange reaction [Formula: see text] can be monitored by conventional nuclear magnetic resonance spectroscopy. The equilibrium constant in diethyl ether-d10 solution is 1.2 ± 0.1 and the rate constant for the forward reaction is 4.95 ± 0.25 × 10−5 l mole−1 s−1 at 35°. Dimethylarsine exchanges rapidly with methanol-d4and bis(trifluoromethyl)arsinic deuteride.
Excess enthalpy, volume, and Gibbs free energy of n-propanol – isopropanol mixtures at 25 °C
Authors: polák Jiří , Murakami Sachio , Benson G. C. , Pflug H. D.
Published: May 2006

The results of calorimetric, dilatometric, and circulation still studies of the system n-propanol – isopropanol at 25 °C are reported. Examination of the behavior of the excess properties indicates that deviations from ideality can be attributed mainly to the formation of mixed association complexes.
Fluorinated carbohydrates. Part V. Nuclear magnetic resonance data on pyranose and furanose derivatives of 3-deoxy-3-fluoro-D-glucose
Authors: Foster A. B. , Hems R. , Hall L. D.
Published: May 2006

The n.m.r. spectra of a series of 3-fluorinated glucose derivatives have been measured; spectral assignments were confirmed by 1H–{19F} heteronuclear decoupling experiments. The 19F spectral parameters illustrate a variety of stereospecific dependencies, the most noteworthy being that of 4JF,H couplings, for which 4Je,e = ca. + 4.0 Hz while 4Je,a = ca. − 1.5 Hz.
Anodic Oxidation of Ethylene Glycol on Platinum: a Mechanistic Study
Authors: Vijh Ashok K.
Published: May 2006

Anodic oxidation of ethylene glycol (EG) has been examined on platinum in 1 N H2SO4 by means of potentiostatic and potentiodynamic techniques. Experimental results consist of steady-state, potential-current relationships, reaction order derivatives, inhibition inflections, potentiodynamic profiles, and product analysis. Reaction mechanism has been proposed by combining these results with the previous information on the adsorption of EG on platinum, and on the pH effects in the anodic oxidation of EG. An analysis of these data has been presented in terms of kinetics under both Langmuir and Temkin conditions of electrode coverage. Inhibition inflections have been interpreted in terms of the kinetic theory of passivation effects proposed by Gilroy and Conway. It has been suggested that a chemical step of the type Pt.EG + Pt.OH → Pt.R + H2O + Pt is the likely rate-determining-step (r.d.s.). The data indicate that quasi-equilibria prior to the r.d.s. are probably different in the ascending and descending direction of potentials (on the potential–current curves), owing to the presence of different extents of oxygenated (Pt.OH or Pt.O) adsorbed species and the associated effects of coverage on kinetics.
Kinetics of Thermal Decomposition of Aqueous Perchloric Acid
Authors: Henderson M. Patricia , Miasek Viola I. , Swaddle T. W.
Published: May 2006

Thermal decomposition of 1.1–6.6 m aqueous perchloric acid at 295–322° yields oxygen, chlorine, and a small quantity of hydrochloric acid. The initial rates of decomposition have been measured, using a perchlorate ion activity electrode, and show 3.5 order dependence on the stoichiometric perchloric acid concentration; the corresponding rate coefficient and activation energy at 300.0° are 3.1 × 10-7 m −2.5 s−1 and 84 kcal mole−1, respectively. The order of reaction with respect to time is less than 3.5 and depends upon the initial perchloric acid concentration; this effect is due to acceleration of the decomposition by the reaction products, notably chloride ion. It is suggested that the rate-determining step in the decomposition of aqueous perchloric acid is the reaction of two undissociated HClO4 molecules to give H2O, ClO3, and ClO4.
Measurement of Depolarization Ratios in the Raman Spectra of Powdered Crystalline Solids
Authors: Johnson D. W. , Sutton D.
Published: May 2006

The change in apparent depolarization ratio as a function of the refractive index of the surrounding liquid medium has been measured for the Raman active vibrational modes of powdered crystalline barium nitrate and sodium sulfate. This method provides an accurate measurement of the refractive index and depolarization ratios for barium nitrate, but fails to do so for sodium sulfate due to birefringent effects. The general applications of this technique for determining depolarization ratios of powdered crystalline solids are discussed.
Aqueous Nonelectrolyte Solutions. Part VIII. Deuterium and Hydrogen Sulfides Solubilities in Deuterium Oxide and Water
Authors: Clarke E. C. W. , Glew D. N.
Published: May 2006

A new apparatus is described in which the solubility of deuterium sulfide in deuterium oxide and of hydrogen sulfide in water have been determined with 0.1 % accuracy between 0 and 50 °C. Solubility equations are derived and the solubility standard thermodynamic function changes, together with their standard errors, are tabluated. Equal solubilities would occur at −1 °C. The solubility of hydrogen sulfide in water is greater than for deuterium sulfide in deuterium oxide, the solubility difference increases to a maximum at 40 °C and thence decreases at higher temperatures.
Nitrato and Acetylacetonato Complexes of Copper(I)
Authors: Anderson W. A. , Carty A. J. , Palenik G. J. , Schreiber G.
Published: May 2006

Copper(I) nitrate complexes of the types L2CuNO3, L3CuNO3, and L4CuNO3 (L = tertiary phosphine) have been synthesized by reduction of copper(II) nitrate with tertiary phosphines. Infrared spectra and single crystal X-ray measurements indicate the presence of bidentate nitrate in L2CuNO3, monodentate nitrate in L3CuNO3, and ionic nitrate in L4CuNO3.The single crystal X-ray structure of nitratobis (tricyclohexylphosphine)copper(I) is reported. CuO3N(PC18H33)2 crystallizes in the monoclinic space group C2/c with a = 18.18(1) Å, b = 9.240(6) Å, c = 22.41(2) Å, and β = 96.57(5)°. The structure was solved by the heavy atom method and refined with isotropic thermal parameters to an R of 0.14. The copper atom is tetrahedrally coordinated by two phosphorus atoms and two oxygen atoms of a bidentate nitrate group. The P—Cu—P angle (140(1)°) and Cu—P bond lengths (2.29(1) Å) are the largest reported for tetrahedral copper complexes.A facile synthetic route to acetylacetonatobis(phosphine)copper(I) complexes is also described.
Preparation of Substituted Anisylic Phenyl Ethers
Authors: Prokipcak J. M. , Breckles T. H.
Published: May 2006

It is shown that anisylic phenyl carbonates thermally decompose to yield the corresponding anisylic phenyl ethers. The method involves heating the carbonates to their decomposition temperatures using hexamethylphosphoramide or toluene as a solvent. Thirteen anisylic phenyl ethers were prepared in good to excellent yields by this apparently general and simple procedure.
Potential Energy- Sheets for the nπ* and ππ* Triplet States of Acrolein
Authors: Devaquet A. , Salem L.
Published: May 2006

The energy of the nπ* and ππ* triplet states of acrolein as a function of the twist of the CH2 terminal groups and relaxation of the three skeletal σ bonds has been investigated in an "ab initio" self-consistent field formalism. The potential energy sheets of these triplets show that the cis photoadducts of cyclic enones may arise from "planar, relaxed" triplet states whereas the trans photoadducts are given by "twisted, unrelaxed" triplet states.
Ellipsometric Determination of the Spectra of Adsorbed Molecules
Authors: Dignam M. J. , Rao B. , Moskovits M. , Stobie R. W.
Published: May 2006

This paper presents a detailed analysis of the application of ellipsometry to obtaining the optical spectra (principally infrared (i.r.)) of molecules adsorbed on reflecting surfaces. Both external and total internal reflections are considered and the conditions for optimum sensitivity examined. A new empirical quantity, the relative complex optical density, is defined which exhibits thin film properties well, particularly in the case of multiple reflection measurements. An explicit expression is derived for this density function (relating it to the optical constants of the media and other system parameters), which is both reasonably simple and correct to second order terms in the film thickness. It is shown that for thin films, no higher order terms need be included, but that in general the second order term must be retained. Various limiting cases are examined to gain insight into the optical behavior of thin films, and to the same end, model calculations performed for CCl4 physically adsorbed on Ag, Ni, Sb, and Ge. In relation to conventional reflection spectroscopy, ellipsometric spectroscopy is shown to have three major advantages: (1) in general, higher sensitivity to adsorbate properties; (2) very much lower sensitivity to absorption of radiation by the adjacent gas phase; (3) more information, permitting the optical constants and film thickness to be determined. Finally, the practicability of the technique is demonstrated by presenting preliminary results for CH3OH reversibly adsorbed on Ag, showing clearly the C—H stretching bands.
Collisional Deactivation Rates of N2+ (B2Σu+)
Authors: Mackay G. I. , March R. E.
Published: May 2006

Electron beam excitation of nitrogen was utilized to produce ions in the zeroth and first vibrational levels of the B2Σu+ state. The rate constants for the collisional deactivation of electronically excited N2+, for each of N2 and NO, were determined individually for the v′ = 0 and v′ = 1 vibrational levels of the N2+(B2Σu+) state. Charge transfer is the most probable mode of deactivation.
Chemical Shift. V. Further Studies on the Long-range Shielding Effects of the C—H and C=O Bonds
Authors: ApSimon J. W. , Beierberck H.
Published: May 2006

The long-range shielding effects of the C=O and C—H bonds were reexamined by the method described in part IV of this series, with the objective of resolving the discrepancies between some of the conclusions presented and earlier findings by Zürcher. The C—H bond magnetic anisotropy was treated as a variable and found to be small enough to be negligible. Upon omission of this term, both electrostatic and magnetic anisotropy effects had to be invoked to account for the shielding effects of the carbonyl group.The necessary geometric quantities were calculated from atomic coordinates for androsterone, as determined by X-ray crystallography, and freely rotating methyl groups were approximated by superpositions of 24 conformations of the group. The results were in essential agreement with those obtained with the use of geometric factors computed as described in part IV.
On the Reaction of N-Bromoacetamide with Olefins. Preparation and Chemistry of 2-Bromo-N-Bromoacetimidates, a New Class of Compounds
Authors: Wolfe Saul , Awang D. V. C.
Published: May 2006

A historical and mechanistic review of the Wohl-Ziegler reaction (allylic bromination by N-bromo-amides and imides) is presented as an introduction to the present work, a re-examination of the reaction of N-bromoacetamide (NBA) with some olefins. The reaction has been found to lead not to allylic bromination but, rather, to 2-bromo-N-bromoacetimidates, a new class of compounds. The stoichiometry of the reaction is: olefin + 2 NBA → adduct + acetamide. The process appears to occur in two stages, viz., a free radical reaction of NBA with itself to form N,N-dibromoacetamide (NDBA), followed by ionic addition of NDBA to the double bond. Hofmann's synthesis of NDBA has been repeated; the compound reacts rapidly with cyclohexene to give the same adduct 10 as does NBA. A variety of stereochemical and selectivity data suggest that this is an ionic addition.The chemical transformations of 2-bromo-N-bromoacetimidates under thermal, acidic, and basic conditions are discussed.
Vibrational Spectral Studies of Hexaquozinc Nitrate and Hexaquozinc Nitrate-d2
Authors: Brooker M. H. , Irish D. E.
Published: May 2006

Infrared and Raman spectra are reported for the hexaquozinc nitrate crystal. Replacement of water by deuterium oxide causes a remarkable intensity reversal of components in the ν3 nitrate region and provides Raman spectra free from interference in the 2ν2 and ν4 regions. The nitrate spectrum is interpreted in terms of a site group approximation. The spectra are compared with those of concentrated aqueous solutions and partially dehydrated crystals to point up changes which result from a lowered site symmetry and those which result from ionic association.
Preparations of Some Tetrahydronaphthalenone and Dihydroindanone Derivatives of Potential Value as Intermediates for the Synthesis of Steroids and Related Compounds
Authors: Jones J. Bryan , Leman Jeffrey D. , Marr Peter W.
Published: May 2006

The difficulties which in the past have precluded the preparation of some synthetically potentially useful ethylenedioxy-tetrahydronaphthalenone and -dihydroindanone derivatives have been overcome. The proclivity of the tetrahydronaphthalenone compounds to undergo acid- and base-catalyzed rearrangements has been shown to be paralleled to some extent by the analogous dihydroindanone compounds.
Kinetics of Reactions of 8-Quinolinol and Acetate with Hydroxyaluminum Species in Aqueous Solutions. 2. Initial Solid Phases
Authors: Turner R. C.
Published: May 2006

The effects of pH and concentrations of 8-quinolinol and acetate on the rate of release of mononuclear Al from an initial solid phase formed by the rapid precipitation of mononuclear Al cations and from another formed by the precipitation of polynuclear hydroxyaluminum cations with NaOH were determined. With the solid formed by precipitation of the mononuclear Al cations, the rate was governed by the rate of dissolution of the solid. Dissolution occurred because the solution was undersaturated with respect to the solid. With the solid formed by the precipitation of the polynuclear cations the reaction behaved as if the rate determining step in the release of the mononuclear Al was the decomposition of the polynuclear cations after dissolution of the solid, indicating that the polynuclear cations persisted as such in the precipitate.Independent evidence that the two initial solid phases were entirely different was indicated by the fact that the one formed by precipitation of mononuclear cations developed into gibbsite in a few days whereas the other did not.
Catalysis of the Reduction of Hydroperoxides by Triphenylphosphine
Authors: Hiatt R. , McColeman Christine
Published: May 2006

The reaction of hydroperoxides with triphenylphosphine is catalyzed by the addition of strong acid. Likewise in hydroxylic solvents, the log of the bimolecular rate constant increases linearly with the solvents' autoprotolysis constants. Soluble salts of molybdenum or vanadium are 104 to 105 times more effective catalysts than H+. The reaction shows promise as a method for quantitative comparison of the effectiveness of these compounds in augmenting the electrophilic character of hydroperoxides.
Sur la formation de composés bicycliques lors de réactions de Friedel–Crafts
Authors: Dufort N. , Jodoin B. , Lafontaine J.
Published: May 2006

The acylation of 1-methylcyclohexene with propionyl, butyryl, and benzoyl chloride in the presence of different Lewis acids is reported. The exo and endo 1-acyl-6-methyl bicyclo [3.1.0]hexane isomers are formed with variable percentages depending upon the catalyst used. An unexpected compound, 3-benzoyl-2-methylcyclohexanol, was isolated from the reaction of 1-methylcyclohexene with benzoyl chloride. The acylation of 1,3,3,5,5-pentamethylcyclohexene with acetyl chloride – stannic chloride gave no bicyclic compounds.
Total Synthesis of Several Monodeoxy and Dideoxy-DL-hexopyranoses from 6,8-Dioxabicyclo[3.2.1]oct-2-ene and 6,8-Dioxabicyclo[3.2.1]oct-3-ene
Authors: Murray T. P. , Singh U. P. , Brown R. K.
Published: May 2006

Reaction of osmic acid with 6,8-dioxabicyclo[3.2.1]oct-3-ene (1) gave 1,6-anhydro-4-deoxy-β-DL-ribo-hexopyranose (3, R = H) which was hydrolyzed to 4-deoxy-α,β-DL-ribo-hexopyranose (4, R = H). Conversion of 1 to 1,6:2,3-dianhydro-4-deoxy-β-DL-ribo-hexopyranose (5) followed by treatment of 5 with lithium aluminum hydride, gave 1,6-anhydro-3,4-dideoxy-β-DL-erythro-hexopyranose (6, R = H), and this in turn was hydrolyzed to 3,4-dideoxy-α,β-DL-erythro-hexopyranose (7, R = H).Reaction of osmic acid with 6,8-dioxabicyclo[3.2.1]oct-2-ene (2) gave 1,6-anhydro-2-deoxy-β-DL-riob-hexopyranose (8, R = H), which was hydrolyzed to 2-deoxy-DL-riob-hexopyranose (9, R = H). Compound 2 was converted to 1,6:3,4-dianhydro-2-deoxy-β-DL-ribo-hexopyranose (10) which was hydrolyzed by aqueous base to 1,6-anhydro-2-deoxy-β-DL-arabino-hexopyranose (12) and this in turn was hydrolyzed by dilute hydrochloric acid to 2-deoxy-α,β-DL-arabino-hexopyranose (2-deoxy-DL-glucose) (13). The reaction of 10 with lithium aluminum hydride gave 1,6-anhydro-2,3-dideoxy-β-DL-erythro-hexopy-ranose (14).Yields were good to excellent in each of the above reactions.
Orientation of Solute Molecules in Nematic Liquid Crystal Solvents
Authors: Robertson J. C. , Yim C. T. , Gilson D. F. R.
Published: May 2006

The tendency of solute molecules to align with their longest dimension parallel to the optic axis of a nematic liquid crystal solvent can be explained by a simple model, based on dispersion force interactions, relating S-values obtained from nuclear magnetic resonance measurements, to molecular dimensions.
Selected Catalytic Decompositions of Indole-2-diazoketone
Authors: Bhandari Kuldip S. , Snieckus Victor
Published: May 2006

Whereas Wolff rearrangement of indole-2-diazoketone (1) in the presence of silver benzoate led to the indolyl-2-acetic esters 2a and b in low yields, the reaction of 1 in methanol with copper powder or with acidic resin gave methoxymethyl-2-indolyl ketone (3) in 65–80% yields. Chloromethyl 2-indolyl ketone (4) was prepared and converted to the α-aminoketone hydrochloride salts 5a and b. Treatment of 1 with cuprous iodide in acetonitrile–methanol gave 2a, iodomethyl 2-indolyl ketone (6), and methyl 2-indolyl-glyoxalate (7). Compound 6 was converted to N-(2-(2-indolyl)-2-oxoethyl)pyridinium iodide (8) and to 2-acetylindole (9) while 7 was degraded via indole-2-glyoxylic acid (10) to indole-2-carboxylic acid (11). Compound 7 represents a type of product not previously observed in diazoketone chemistry. The mechanism of its formation is discussed.
The Mode of Formation and some Reactions of 2,3,6,7-Tetramethoxy-9,10-dimethylphenanthrene
Authors: Weisgraber Karl H. , Weiss Ulrich
Published: May 2006

Reaction of veratrole and biacetyl in 70% aqueous H2SO4 very rapidly yields 3,3-bis-(3,4-dimethoxy-phenyl)-2-butanone (3), which is slowly converted further to 2,3,6,7-tetramethoxy-9,10-dimethylphenanthrene (1). The reaction sequence leading to 1 is interpreted on the basis of this finding, and some new reactions of 1 are described.
Radiation-induced Rearrangement of Ethylene Glycol in Aqueous Solution
Authors: Burchill C. E. , Perron K. M.
Published: May 2006

Under γ-irradiation, aqueous solutions of ethylene glycol containing hydrogen peroxide form acetaldehyde as a major product via a free-radical chain rearrangement. The yield of acetaldehyde is essentially unchanged when hydrogen peroxide is replaced by N2O or HClO4. A mechanism is proposed in which the glycol radical, ĊOHCH2OH, rearranges to the acetaldehyde precursor, ĊH2CHO, followed by the hydrogen atom transfer reaction;[Formula: see text]thus propagating a chain reaction.2The rearrangement is also induced by the photo-dissociation of H2O2 in aqueous solutions of ethylene glycol.
On the Triplet Energies of the Trifluorobenzenes and of cis-Butene-2
Authors: Semeluk G. P. , Stevens R. D. S.
Published: May 2006

Evans' method of high pressure oxygen induced singlet–triplet absorption spectra were used to estimate the triplet energies of the title compounds. Phosphorescent emission spectra from EPA glassy matrix at 77 °K were taken for the trifiuorobenzenes. The 0–0 bands of the T ← S absorption indicate that the triplet energy of cis-butene-2 is lower than that of all three trifluorobenzenes.
Composition of Tetrahydrofuran Hydrate and the Effect of Pressure on the Decomposition
Authors: Gough S. R. , Davidson D. W.
Published: May 2006

The decomposition temperature of the structure II clathrate hydrate of tetrahydrofuran has been followed to pressures above 3 kbars, where the hydrate is found to decompose incongruently in the regions of stability of ices III and II, with no evidence of formation of a denser hydrate. From measurements of liquid solution densities and of volume changes at hydrate decomposition the density of the hydrate was obtained. Comparison with the X-ray lattice dimension indicates that at least 98% of the large cages are occupied, the principal uncertainty being in the lattice parameter. A similar treatment is made of Tammann and Krige's data (23) for chloroform hydrate. Analysis of the results of 18 composition determinations of structure II hydrates shows no statistical evidence of departure from the ideal composition of 17 mol of water per mol of hydrate former.
Reaction of Bis(trifluoromethyl)diazomethane with Bis(trimethylsilyl)acetylene
Authors: Cullen W. R. , Hou F. L.
Published: May 2006

The reaction of bis(trifluoromethyl)diazomethane with bis(trimethylsilyl)acetylene yields 1,2-bis-(trimethylsilyl)-3,3-bis(trifluoromethyl)cyclopropene in low yield. The cyclopropene has an unexpectedly high C=C stretching frequency.
Methyl 2,3-O-Isopropylidene-β-D-ribo-pentodialdofuranoside: a Useful Intermediate in Chain Extension Reactions
Authors: Butterworth Roger F. , Hanessian Stephen
Published: May 2006

Oxidation of methyl 2,3-O-isopropylidene-β-D-ribofuranoside with the "Pfitzner–Moffatt" reagent (methyl sulfoxide – dicyclohexylcarbodiimide) provides an efficient route to the corresponding 5-aldehydo derivative. Oxidation with methyl sulfoxide - acetic anhydride mixtures affords low yields of the aldehyde, the 5-acetate and 5-O-methylthiomethyl ether derivatives being the principal products.
Isocarbostyrils. II. The Conversion of 2-Methyl-4-acyl-5-nitroisocarbostyrils to 2-Substituted Indole-4-carboxylic Acids
Authors: Horning D. E. , Lacasse G. , Muchowski J. M.
Published: May 2006

The sulfuric acid catalyzed acylation of 2-methyl-5-nitroisocarbostyril with carboxylic acid anhydrides gave the corresponding 4-acylated derivatives 3, which underwent reductive cyclization to 2-substituted derivatives of 4-methyl-1,3,4,5-tetrahydropyrrolo[4.3.2.de]isoquinolin-5-one (4). Alkaline hydrolysis of the six-membered lactam in 4 was accompanied by a retro-Mannich reaction to produce 2-substituted indole-4-carboxylic acids in about 40 % overall yield from 3.
Temperature Dependence of Disproportionation–Combination Ratios for Alkyl Radicals in Liquid Methane
Authors: Gillis Hugh A.
Published: May 2006

The ratios of rate constants for disproportionation to combination have been measured for ethyl radicals and for i-propyl radicals in liquid methane between −181 and −94 °C. The radicals were generated by γ-radiolysis of dilute methane solutions of ethylene-d4 or propylene-d6. The activation energy for combination was found to exceed that for disproportionation by 290 ± 30 cal mol−1 for ethyl radicals and by 255 ± 25 cal mol−1 for i-propyl radicals. In both cases the disproportionation—combination ratio in the liquid, extrapolated to room temperature, is greater than that in the gas phase by a factor of about 2.5. These results are interpreted as indicating that disproportionation and combination reactions proceed by way of different transition states.
Photochemistry of Oximes III. The Photochemical Beckmann Rearrangement
Authors: Cunningham M. , Lim L. S. Ng , Just G.
Published: May 2006

Cycloalkanone oximes of ring-size four to fifteen are shown to yield lactams upon irradiation in methanol solution. Acyclic ketoximes similarly yield Beckmann-type products in methanol solution. Unlike the Beckmann rearrangement, unsymmetrically α-substituted cyclohexanone oximes give mixtures of approximately equal parts of both possible lactam isomers. The photolysis of oximes epimeric at the α-carbon gives products in which the α-center has retained its configuration. The results are interpreted in terms of a concerted breakdown of an oxazirane intermediate.
Molecular Beam Chemiluminescence. I. Kinetic Energy Dependence of the NO + O3 → NO2* + O2 Reaction
Authors: Redpath Anthony E. , Menzinger Michael
Published: May 2006

The visible Chemiluminescence of the NO + O3 → NO2* + O2 reaction has been studied as a function of collision energy using a supersonic molecular beam of NO. The reaction threshold E0 = 3.00 ± 0.45 kcal/mol is found to lie significantly below the Arrhenius activation energy of Ea = 4.18 ± 0.3 kcal/mol. This clearly demonstrates the basic difference between the two quantities.
La désamination nitreuse des aminométhyl-1 phénylsulfonyl-4 cyclohexanols-1 cis et trans
Authors: Favre H. , Hamlet Z. , Menard M. , Roblot G. , Temler J.
Published: May 2006

Nitrous acid deamination of cis-1-aminomethyl-4-phenylsulfonyl-1-cyclohexanol gives 60% of epoxide and 23% of ring-expanded ketone whereas the trans isomer gives 28% of epoxide and 60% of ring-expanded ketone. The large proportion of epoxide is accounted for by the inductive effect and the field effect of the phenylsulfonyl group; a conformational effect wherein the CH2NH2 group leads to more epoxide when in an equatorial conformation than in an axial is also observed in this reaction. This study required the preparation of 4-phenylthio and 4-phenylsulfonyl cyclohexanols and cis- and trans-1-methyl cyclohexanols.
La réaction du diazométhane avec les phénylsulfonyl-4, tert-butyl-4, et phénylthio-4 cyclohexanones
Authors: Favre H. , Gravel D. , Hamlet Z. , Ménard M. , Temler J.
Published: May 2006

This paper describes the reaction of diazomethane generated in situ, methanolic potassium hydroxide solution, on 4-phenylsulfonyl, 4-tert-butyl, and 4-phenylthio-cyclohexanones. In the latter two cases, the reaction leads to mixtures containing mostly the enlarged ketones along with minor quantities of the corresponding epoxides. In the first case, the enlarged ketone and the corresponding epoxides are formed in equal amounts. This marked increase in the production of epoxides is indicative of transannular interactions between the sulfonyl group and the intermediate betaine. In the ex situ reactions, methanolic solutions without potassium hydroxide, phenylsulfonylcyclohexanone yields the corresponding dimethyl acetal almost exclusively whereas the tert-butyl and phenylthioketones follow the same course as in the in situ reactions. Furthermore, it has been observed in all cases that, under the conditions used, the potassium hydroxide leads to opening of the epoxide rings to yield hydroxy-ethers of the type [Formula: see text]CH2—O—CH3. This epoxide-ring-opening was advantageously used in the preparation of pure epoxides from epimeric mixtures. The epoxides generated from the three ketones studied are mixtures of cis-trans isomers, rich in cis epimer.
An Unusual Course of a Nitro Sugar Acetylation: Formation of a Crystalline Nitronic Acid – Acetic Acid Mixed Anhydride
Authors: Rank Werner , Baer Hans H.
Published: May 2006

Whereas acetylation of methyl 4,6-O-benzylidene-3-deoxy-3-nitro-β-D-mannopyranoside (1) and its β-D-galacto isomer 2 with acetyl chloride and triethylamine in ether furnished the expected 2-O-acetylated nitro glycosides, 1a and 2a, the same method applied to the α-D-talo isomer 3 gave the 2-O-acetyl derivative of the corresponding nitronic acid – acetic acid anhydride, 4.
Low Temperature Infrared and Raman Spectra of Lithium Borohydride
Authors: Harvey K. B. , McQuaker N. R.
Published: May 2006

The infrared spectra of polycrystalline LiBH4 and LiBD4 have been recorded in the region 4000–50 cm−1 at 80 °K. Raman spectra of polycrystalline samples were also recorded at this temperature. The spectra of the [Formula: see text]and [Formula: see text]lattice vibrations are consistent with symmetrically equivalent borohydride ions which lie on either general positions, two-fold axes or mirror-planes. Six lattice vibrations of translatory origin appear in the infrared spectrum of LiBH4 and a mode of libratory origin is inferred from an absorption tentatively assigned as a second overtone of a librational mode. Similar spectral results are obtained for LiBD4. The inferred librational frequencies are 418 cm–1 for the [Formula: see text] ions and 319 cm–1 for the [Formula: see text] ions.
Determination of the Bond Dissociation Energy D(C2H5Hg—C2H5) by the Toluene Carrier Method
Authors: Lalonde A. C. , Price S. J. W.
Published: May 2006

The pyrolysis of diethylmercury has been studied in a toluene carrier flow System from 601 to 673 °K using total pressures of 1.04 to 7.75 mm. The progress of the reaction was followed by measuring the amounts of unreacted alkyl. Partial solution of butane in the toluene condensed at the outlet of the reactor made full product analysis difficult. Complete analysis in a number of runs did yield a good material balance between alkyl decomposed and [Formula: see text].[Formula: see text][Formula: see text][Formula: see text][Formula: see text]The Arrhenius equation for reaction 1, log k1(s−1) = 15.4 − (45 700 ± 1 000)/2.3 RT, is in excellent agreement with that estimated by Benson and O'Neal. Based on a number of simplifying approximations, log k3(cm3mol−1s−1) = 10.9 − (9 300 ± 2 000)/2.3 RT. The estimated disproportionation to combination ratio, K5/K4 = 0.09 – 0.12 is in good agreement with earlier work.Approximate correction of E1 to absolute zero yields D(C2H5Hg—C2H5) = 43.7 kcal mol−1 and therefore by difference D(Hg—C2H5) = 6.5 kcal mol−1.
Crystal and Molecular Structure of Dichlorobis(4-methylpyridine)zinc(II), Zn(4-CH3Py)2Cl2
Authors: Lynton H. , Sears M. C.
Published: May 2006

Crystals of dichlorobis(4-methylpyridine)zinc(II), Zn(4-CH3Py)2Cl2, are monoclinic, space groupP21/c, with a = 14.294(13), b = 7.885(8), c = 13.473(11) Å, β = 100.60(5)° and 4 molecules in the unit cell. The final atomic parameters were obtained from a block-diagonal least squares refinement using anisotropic thermal parameters. The hydrogen atom positions were established but the parameters were not refined. The final agreement residual for 1348 observed reflections is R = 0.043. The zinc atom is tetrahedrally coordinated.
Isolation and Structure of a Dilignol Rhamnoside From the Leaves of Thuja plicata Trees
Authors: Manners Gary D. , Swan Eric P.
Published: May 2006

The isolation of a series of dilignol glycosides from the leaves of western red cedar trees is described. The structure of the first member of this series was determined by chemical degradation reactions and n.m.r. and mass spectra of its derivatives. It is 1-(3′-methoxy-4′-hydroxyphenyl)-2-O-1″-[2″-hydroxy-4″-(propane-3′′′-O-α-L-rhamnopyranoside)phenyl]-propane-1,3-diol (1). The novel features of this compound are discussed, together with its possible roles in the leaves.
Kinetic Solvent Isotope Effect for the Spontaneous Solvolysis Acetic and Propionic Anhydrides
Authors: Robertson R. E. , Rossall B. , Redmond W. A.
Published: May 2006

The large kinetic solvent isotope effects for the neutral hydrolysis of acetic and propionic anhydride show unusual temperature dependency; the former passing through a maximum at about 15°, the latter showing a minimum at 30°. This unusual temperature dependency is the consequence of widely different values of the apparent ΔCp≠ in H2O and D2O: the value for acetic anhydride in H2O being −74 ± 2 cal deg−1 mol−1 but −32 ± 4 in D2O. The corresponding values for propionic anhydride being −31 ± 2 in H2O but −94 ± 10 in D2O. The implications of these differences are discussed.
The Effect of Electric Fields on the Radiolysis of Acetylene, and the Mechanism of Cuprene Formation
Authors: Briggs J. P. , Back R. A.
Published: May 2006

Gaseous acetylene at pressures of about 200 Torr was irradiated with γ-rays at doserates between about 1011 and 1012 eV/cc s, with and without an electric field applied. The deposition of cuprene on the bottom of the reaction vessel was markedly affected by the field, but the rate of cuprene formation as measured by the pressure decrease was unchanged. Examination of the cuprene deposit with an electron microscope showed it to consist of rather uniform spheres averaging about 3000 Å in diameter, with each containing an estimated 2 × 108 molecules of acetylene. The mechanism of cuprene formation is discussed, and it is suggested that it does not proceed through a direct polymerization of acetylene, but involves a secondary polymerization of polyene intermediates, in the gas phase and after their condensation in liquid droplets.
On the Existence of Free OH Groups in Liquid Water
Authors: Péron J.-J. , Bourdéron C. , Sandorfy C.
Published: May 2006

It is shown that despite the complexity of the related parts of the spectrum, vibrational overtones give evidence of the presence of free OH groups in liquid water.
Bond Enthalpy for the Phenol–Benzene Complex
Authors: Bloser Donald , Murphy Joseph , Spencer J. N.
Published: May 2006

The [Formula: see text] hydrogen bond enthalpy for the phenol–benzene complex has been determined spectrophotometrically. Equilibrium constants for the hydrogen bonded complex are reported. The [Formula: see text] bond enthalpy was found to be −4.1 ± 0.5 kcal mol−1 and the entropy change −17 cal deg−1 mol−1.
The Isothermal Compressibility of Organic Liquids by Ultracentrifugation. Correlation with Surface Tension
Authors: Richard Alfred J. , Rogers Kenneth S.
Published: May 2006

Isothermal compressibilities of seven organic liquids have been determined by analytical ultracentrifuge techniques, in good agreement with literature values obtained by other methods.A least squares regression equation was derived that correlated the logarithmic values of isothermal compressibilities of 7 organic liquids, determined experimentally, with the liquids' surface tensions. This equation was shown to be valid for 11 other organic liquids (values obtained from literature) over a temperature range of 0° through 50°, and a surface tension range of 13 to 44 dyn per cm.
Formation des dérivés N- et C-substitués au cours de l'alkylation de l'indol-2(3H)-one
Authors: Gruda Ilona
Published: May 2006

The alkylation of indol-2(3H)-one (oxindole) and of some of its mono and dialkyl derivatives has been investigated.Chromatographic methods for preparative separation and quantitative determination of the five compounds formed in the reaction between oxindole and benzyl chloride in the presence of a base are reported.A kinetic approach to these reactions shows that in unsubstituted indol-2(3H)-one the 3-position is twice as reactive as the 1-position. In the already 3-monosubstituted compound the reactivity of the 3-position is about 30 times greater than that of the 1-position.
Vibrational Spectra of SiH4 and SiD4–SiH4 Mixtures in the Condensed States
Authors: Fournier R. P. , Savoie R. , The Nguyen Dinh , Belzile R. , Cabana A.
Published: May 2006

The i.r. and Raman spectra of liquid and crystalline SiH4 and SiD4–SiH4 mixtures have been recorded. The spectra show striking changes when the crystal undergoes the solid–solid phase transition. Phase I is disordered. Possible site, and factor groups for the low temperature crystalline phase are proposed.
The Photodecomposition of an Analogue of DDT
Authors: Liu H. J. , Silk P. J. , Unger I.
Published: May 2006

The photodecomposition of 1,1,1-trichloro-2,2-bis(5′-chloro-2′-methoxyphenyl)ethane (MPA) has been carried out both in solution and solid phase with exciting light > 300 nm. The major products of the solid phase photolyses are HCl and 1,1-dichloro-2,2-bis(5′-chloro-2′-methoxyphenyl)ethylene (MPE), 5,5′-chloro-2,2′-methoxybenzophenone (MPO), 1,1-dichloro-2,2-bis(5′-chloro-2′-methoxyphenyl)ethane (MPD), and 1-chloro-2,2-bis(5′-chloro-2′-methoxyphenyl)ethane (MPC). In liquid phase and in the presence of O2 the photodecomposition yields many products, the major ones, in addition to HCl, being MPE, MPD, MPC, and MPO. In the absence of O2 in liquid phase only HCl, MPD, MPC, and MPE were observed. In the O2 free photolysis MPD and MPC are produced in larger quantity than MPE. A preliminary investigation has shown that MPE irradiated at λ > 300 nm also photodecomposes. A check carried out by the Canada Department of Agriculture indicates that MPA is a pesticide although it may not be as effective as DDT.
An Electron Spin Resonance Study of High Energy Radiation Damage in Tetrapotassium Hexacyanoruthenate Trihydrate, K4Ru(II)(CN)6•3H2O
Authors: Eachus R. S. , Herring F. G.
Published: May 2006

Gamma-ray irradiation at 77 °K and X-ray irradiation at room temperature of single crystals of the diamagnetic tetrapotassium hexacyanoruthenate trihydrate have been shown to produce a number of interesting paramagnetic species. At room temperature the e.s.r. spectra can be interpreted in terms of the species [Ru(CN)5(NC)]5−. At liquid nitrogen temperature the species [Ru(CN)4(NC)2]5− is observed and the HCN− radical is produced in an environment which does not permit it to rapidly reorientate at 77 °K. The HCN− radical is believed to be in close association with a ruthenium(II) ion.
Carbanions in Carbohydrate Chemistry: Novel Methods for Chain Extension and Branching
Authors: Hanessian S. , Dextraze P.
Published: May 2006

Methods are described for the introduction of two and three carbon units in carbohydrates by the reaction of suitable epoxides with sodio diethyl malonate. The reactions represent a means of branching and chain extension in the carbohydrate series and lead to the incorporation of highly functionalized carbon units at predetermined sites in the sugar molecule.
Molecular Rearrangements. Part I. The Thermal Rearrangement of the Benzyl Naphthyl Ethers
Authors: Badr M. Zarif A. , El-Sherief H. A. H.
Published: May 2006

Heating benzyl-β-naphthyl ether at 260° for some days causes benzylic migration to the α-position, together with the formation of β-naphthol, toluene, dibenzyl, and 9-phenyl-1,2,7,8-dibenzoxanthene.Benzyl-α-naphthyl ether rearranges under similar conditions to give 2- and 4-benzyl-1-naphthol, toluene, dibenzyl, and 9-phenyl-3,4,5,6-dibenzoxanthene.Rearrangement of the benzyl-α-naphthyl ether in quinoline gives the normal products of the rearrangement together with 2- and 4-benzylquinolines and 2-quinolyl-1-hydroxynaphthalene. In phenol and in anisole, the rearrangement is accompanied by benzylation of the solvent.It is concluded that the thermal rearrangement of the benzyl naphthyl ethers depends on a homolytic fission of the ether to benzyl and naphthyloxy radicals.
A Semi-empirical Analysis of the Electronic Spectrum and Molecular Structure of Formaldehyde
Authors: Absar I. , Lin C. S. , McEwen K. L.
Published: May 2006

The electronic transition energies and ionization potentials of formaldehyde have been calculated by a semi-empirical molecular orbital method, using several different ways of evaluating the diagonal matrix elements, in an attempt to adapt the Pariser–Parr–Pople method to the calculation of σ electron properties. The use of theoretically computed penetration integrals in this semi-empirical calculation lead to incorrect relative separation of the π-, σ-, and nonbonding molecular orbital energies, and hence to failure in predicting n →π* and n → σ* transition energies. A method is developed which reproduces the spectrum of formaldehyde (which includes n–π*, π–π*, and n–σ* electronic transitions) satisfactorily. In paper II of this series, this method is applied to study the spectrum of HCN and CO2.
A Simplification in the Synthesis of Deoxyribooligonucleotides
Authors: Narang S. A. , Itakura K. , Wightman R. H.
Published: May 2006

The synthesis of oligonucleotides can be accomplished with no "protection" of the amino function in the case of adenine and guanine bases under the usual reaction conditions.
Thermal Reactions of Sodium Azide in the Presence of Nitric Oxide and Hydrogen
Authors: Back R. A. , Nip W.
Published: May 2006

Nitric oxide (120 Torr) strongly suppressed the thermal decomposition of NaN3 at 350 °C. A relatively slow and complex reaction occurred instead, yielding N2, N2O, NaNO2, and Na2O. Isotopic experiments revealed that most of the N2 (60–80%) came from the azide alone, some from NO alone (10–28%), and a small proportion (5–8%) was mixed, with one atom derived from each reagent. Nitrous oxide initially was derived entirely from NO.Hydrogen (12–75 Torr) also suppressed the normal azide decomposition at 350 °C. In its place, a rapid reaction occurred, consuming H2 and NaN3 and producing N2, NH3, Na, and probably NaNH2.Both systems were complex and probably best described as concerted reactions between the azide and the added gas rather than reactions of NO or H2 with transient nitrogen species formed in the thermal decomposition of the azide.
Organic Sulfur Mechanisms. 12. Reaction of Sulfenes with Triphenylphosphine
Authors: King J. F. , Lewars E. G. , Danks L. J.
Published: May 2006

Phenylmethanesulfonyl chloride (1a) and 2,4-dinitrophenyl phenylmethanesulfonate (1b) react with a mixture of triphenylphosphine and triethylamine to give the benzyltriphenylphosphonium salts (2) in 32 and 87% yields, respectively. Methanesulfonic anhydride (1c) similarly gives the methyltriphenylphosphonium salt. These reactions evidently constitute the first illustrations of the reaction of a sulfene with a trivalent phosphorus compound.
Acid-catalyzed Reactions of Cyclobutanones. II. Generation of Acylium Ions from β,γ-Unsaturated Cyclobutanones
Authors: Lee-Ruff E.
Published: May 2006

Acid-catalyzed rearrangement of 3-methylene-2,2,4,4-tetramethylcyclobutanone (1) gave the γ-lactone of 2,2,3,4-tetramethyl-4-hydroxyvaleric acid. Reaction of 2,2,4,4-tetramethylcyclobutane-1,3-dione (5) with PPA gave diisopropylketone with evolution of carbon dioxide. Acylium ions are postulated as intermediates in both these reactions.