bluuebunny/crossref_metadata_2025 huggingface dataset:
Initial damage centers in γ-irradiated α-aminoisobutyric acid
Authors: Cadena Jr. David G. , Linder Robert E. , Rowlands John R.
Published: May 2006

Electron spin resonance measurements of single crystals of α-aminoisobutyric acid, which are both irradiated and measured at 77 °K, give rise to a strong central absorption line at the center of two weak "satellite" peaks. The species largely responsible for the intensity of the central absorption line has been discussed previously and is considered to be the doubly ionized radical anion. In this paper, evidence is presented which shows that some of the intensity of this central line is contributed by the species giving rise to the satellite lines. Furthermore, this evidence, which is based upon saturation studies, variable temperature measurements, deuteration studies, and complete neglect of differential overlap–self consistent field molecular orbital calculations, suggests that the species giving rise to the satellite spectra is a planar conformation of the radical (CH3)2CCO2H.
Studies on microcapsules. IV. Preparation and some properties of sulfonated polyphthalamide microcapsules
Authors: Koishi Masumi , Fukuhara Naoko , Kondo Tamotsu
Published: May 2006

Sulfonated polyphthalamide microcapsules were prepared by making use of the interfacial polycondensation reaction between p-phthaloyl dichloride and a mixture of diethylenediamine and 4,4′-diaminostilbene-2,2′-disulfonic acid. These microcapsules were found to be fluorescent as well as negatively charged owing to the presence of sulfonated stilbene skeletons chemically bound in the membranes. The electrophoretic mobility measurements in the presence of inorganic electrolytes revealed a strong resemblance between the microcapsules and hydrophobic colloid particles.
An infrared transmission cell for ultra-thin liquid films
Authors: Young R. P. , Jones R. N.
Published: May 2006

This note describes the design and use of an ultra-thin cell for the quantitative measurement of infrared absorption bands of strongly absorbing liquids or solutions by transmission. From these measurements the optical constants of the absorbing material can be evaluated. The technique is demonstrated by a comparison with the optical constant data reported in the literature for the 1527 cm−1 band of hexafluorobenzene as measured by attenuated total reflection.
Reaction of 3-aroylaziridines with aryl isothiocyanates
Authors: Lown J. W. , Dallas G. , Maloney T. W.
Published: May 2006

3-Aroylaziridines react with a variety of aryl isothiocyanates in refuxing benzene to give either (a) 4-aroyl-5-arylamino-4-thiazolines by a [2 + 3] cycloaddition and/or (b) 2-arylamino-4-aroyl-4-thiazolines. When the N-substituent of the aziridine is cyclohexyl or isopropyl the product type (a) is isolated in greater quantity, but when the N-substituent is methyl, product type (b) is isolated in greater quantity. The reactions provide convenient one-step syntheses of new 4-aroyl-4-thiazolines.
Effect of temperature on the Hg6(3P1) photosensitized decomposition of propane
Authors: Campbell J. M. , Gunning H. E. , Strausz O. P.
Published: May 2006

The relative yields of n-propyl and isopropyl radicals from the primary step of the Hg6(3P1) photosensitization of propane have been measured as a function of temperature between 0 and 202 °C. The ratio of n-propyl to isopropyl yield increases with increasing temperature according to the equation[Formula: see text]The primary yields of the propyl radicals were determined from the measured yields of the hexane and pentane products in ethylene scavenging experiments and from the yields of the isomeric hexane products in pure propane, after making proper allowance in the kinetics for all secondary reactions.
The critical constants and orthobaric densities of acetone, chloroform, benzene, and carbon tetrachloride
Authors: Campbell A. N. , Chatterjee R. M.
Published: May 2006

The specific volumes and pressures in the saturated states of the pure liquids acetone, benzene, chloroform, and carbon tetrachloride have been determined from a temperature of 100 °C and a pressure of about 2 atm up to the highest temperatures and pressures at which liquid and vapor coexist. The critical temperatures have been determined by the method of disappearance of meniscus, critical densities from the law of the rectilinear diameter, and critical pressures by extrapolation of the log P vs. 1/T line to the critical temperature.
Mechanism of initiation in the thermal polymerization of styrene. Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine
Authors: Kopecky Karl R. , Evani Syamalarao
Published: May 2006

Thermal decomposition of cis-3,6-diphenyl-3,4,5,6-tetrahydropyridazine, 1, (k = 5.6 × 10−4s−1 at 79.5°) results in the formation of about 60% styrene, 27% cis- and 13% trans-1,2-diphenylcyclobutane. The relative product yields vary little over the temperature range 64–133°. This indicates that 1 decomposes exclusively to the 1,4-diphenyl-1,4-butadiyl diradical, 2, and nitrogen. The diradical, 2, cannot be trapped by styrene and 1 is not an initiator of styrene polymerization. Therefore, 2 is not the radical intermediate responsible for the thermal initiation of styrene polymerization.
New approach to the synthesis of optically active trityl systems
Authors: Rutherford K. G. , Batiste J. L. H. , Prokipcak J. M.
Published: May 2006

A new method for the resolution of potentially optically active trityl alcohols is reported. Three trityl alcohols as pilot compounds were converted to hydracrylic acid derivatives. Esterification with diazo-methane was followed by degradation (reverse Michael reaction) to the original alcohols with sodium hydride. The resolution of phenyl-α-naphthyl-p-tolylcarbinol was effected conveniently by this route.
Distribution of reaction products (theory). VII. D+ + H2 → DH + H+ using an ab initio potential-energy surface
Authors: Csizmadia I. G. , Polanyi J. C. , Roach A. C. , Wong W. H.
Published: May 2006

A three-dimensional classical trajectory calculation has been made of the dynamics of the reaction D+ + H2 → DH + H+. In contrast to earlier trajectory studies the potential-energy surface was obtained ab initio, consequently the results have predictive interest.
Conductances, densities, and viscosities of concentrated solutions of lithium chlorate and of sodium chlorate in water–dioxane mixtures, at 25°
Authors: Oliver B. G. , Campbell A. N.
Published: May 2006

The conductances, densities, and viscosities of sodium chlorate and of lithium chlorate in the solvents 44.5% dioxane–55.5% water and 64.5% dioxane–35.5% water were determined, at 25 °C, almost up to saturation. The apparent molal volume of the electrolytes, calculated from the density data, was found to be greater in the dioxane–water solvents than it is in water, indicating a decrease in solvation in the mixed solvents. The relative viscosity increased as the dioxane content of the solvent increased, showing a larger ordering effect of the electrolytes as the solvent became less hydrogen bonded and less ordered. The equivalent conductance of both electrolytes was greatly reduced as the dioxane content of the solvent was increased, in accord with predictions based on solvent viscosity and dielectric properties. Also, sodium chlorate was found to be more associated than lithium chlorate in the mixed solvents.
Total synthesis, stereochemistry, and lithium–ammonia reduction of (±)-4-demethylaristolone and (±)-5-epi-4-demethylaristolone
Authors: Piers Edward , Waal William de , Britton Ronald W.
Published: May 2006

The total synthesis of (±)-4-demethylaristolone (14) and its epimer, (±)-5-epi-4-demethylaristolone (15) is described. The key step of this synthesis involves the intramolecular cyclization of the olefinic diazoketone 12, which produces the two epimers, 14 and 15, in a ratio of approximately 2:1, respectively. The stereochemistry of the two epimers is unambiguously determined. It is observed that the lithium–ammonia reduction of 14 gives a dihydro derivative 16 containing trans-fused six-membered rings, while, interestingly, a similar reduction of 15 affords the corresponding cis-fused decalone system 26.
Alkoxycarbenes from the thermolysis of silyl ketals
Authors: Brook A. G. , Dillon P. J.
Published: May 2006

It is shown that α,α-dimethoxybenzylsilanes thermally rearrange to give methoxysilanes and phenylmethoxycarbene; the latter species has been trapped by a variety of reagents. The rearrangement involves retention of configuration at an asymmetric silicon center. While α,α-dimethoxyethylsilanes eliminate methanol when heated, methoxybenzhydrylsilanes rearrange to methoxysilane and diphenylcarbene but monomethoxybenzylsilanes or 2-silyldioxolanes do not thermally rearrange up to 250°.
threo- and erythro- β-Hydroxy-DL-aspartic acids
Authors: Jones III Clifton W. , Leyden Donald E. , Stammer Charles H.
Published: May 2006

An improved procedure for the synthesis of threo- and erythro-β-hydroxy-DL-aspartic acids is described. An nuclear magnetic resonance study of both diastereomers indicated that the threo isomer exists primarily as the conformer having anti carboxyl groups while the erythro compound prefers a conformation with gauche carboxyl functions. Possible reasons for this anomaly are presented.
Tautomérie des composés chloroacylés d'aminobenzothiazoles à l'état solide
Authors: Costakis E. , Canonne P. , Tsatsas G.
Published: May 2006

The isolation by crystallization of the tautomeric imido and amido forms of the chloroacetyl and α-chloropropionyl-2 aminothiazoles is reported. A judicious choice of solvents leads to the separation of one or the other tautomer and also allows interconversions.The structure of each form has been determined from the corresponding ultraviolet and infrared spectra.
Solvent reorganization for hydrolysis with hydrogen participation
Authors: Inomoto Y. , Robertson R. E. , Sarkis G.
Published: May 2006

A study of the rates of hydrolysis of 3-Me-2-butyl bromide and methanesulfonate in water leads to values of ΔCp≠ of −80 and −40 cal deg−1 mole−1, respectively. The product was about 85–95 % t-pentanol, the remainder being olefin. The value of ΔCp≠ for the solvolysis of the methanesulfonate in D2O was −44 cal deg−1 mole−1. The kinetic solvent isotope effect (k.s.i.e.) for the latter was unusually low (k.s.i.e. = 1.047 at 5 °C and 1.025 at 25 °C). Deuteration at C-3 led to a reduction in the rate of hydrolysis by a factor of about 2.25. This is consistent with an activation process involving "hydrogen participation" as previously reported by Winstein and Takahashi for solvolysis of the corresponding tosylate in acetic acid. In contrast to the latter work, the reaction in water appears to be uncomplicated.
Some new tetrakis(p-tolyl)cyclobutadiene molybdenum complexes
Authors: Efraty A.
Published: May 2006

Tetrakis(p-tolyl)cyclobutadiene molybdenum dicarbonyl bromide dimer and (tetrakis(p-tolyl)cyclobutadiene)(cyclopentadienyl)molybdenum carbonyl bromide were prepared and their structures studied by proton magnetic resonance. An improved synthesis of tetraphenylcyclobutadiene molybdenum dicarbonyl bromide dimer is also described.
Dielectric and nuclear magnetic resonance properties of a clathrate hydrate of cyclopropane
Authors: Majid Y. A. , Garg S. K. , Davidson D. W.
Published: May 2006

Dielectric relaxation data and proton magnetic resonance spectra are given for the structure I clathrate hydrate of cyclopropane. Vapor pressures have been measured along the structure I – structure II – gas equilibrium line missing from the recent phase diagram of Hafemann and Miller.
Isolation of the initial step in the thermal decomposition of di-tert-butyl peroxide
Authors: Yip C. K. , Pritchard H. O.
Published: May 2006

The thermal decomposition of di-tert-butyl peroxide in the presence of propane has been studied at total pressures up to 100 atm. At the highest propane concentrations, the major product of the decomposition is tert-butyl alcohol, and extrapolation to infinite propane pressure indicates that the initial step in the peroxide decomposition is exclusively the formation of two tert-butoxy radicals. The activation energy for the abstraction of hydrogen from propane by t-BuO radicals is discussed.
Chemical examination of the wax from needles of black spruce (Picea mariana) and balsam fir (Abies balsamea)
Authors: Beri R. M. , Lemon H. W.
Published: May 2006

A waxlike substance extracted from the needles of black spruce by means of petroleum ether gives, upon saponification, capric, lauric, myristic, pentadecanoic, palmitic, stearic, oleic, linoleic, linolenic, arachidic, behenic, lignoceric acids, and one acid not identified. Acids of the C-20 to C-24 series constitute approximately 38% of the total acids. The unsaturated acids present are mostly of the C-18 series. The acids were identified by the gas–liquid chromatography (g.l.c.) of their methyl esters.The constituent acids of the waxlike substance from balsam fir needles are capric, lauric, myristic, pentadecanoic, palmitic, palmitoleic, heptadecanoic, stearic, oleic, linoleic, linolenic, arachidic, behenic, lignoceric, and about 7 more, not identified. The acids of the C-20 to C-24 series are present to the extent of ca. 20%. About 55% of the acids are of the C-18 series, which is mostly unsaturated. There are present certain unsaturated acids, ca. 5%, of the C-20 to C-22 series.10-Nonacosanol has been isolated from the unsaponifiable matter remaining after saponification of the waxlike substances from black spruce and balsam fir foliage. Its identity has been established by infrared, nuclear magnetic resonance, and mass spectrometry.
Study of some bisnorquassin derivatives
Authors: Findlay J. A. , Langler R. F. , Tandon J. S.
Published: May 2006

The structures of several derivatives of bisnorquassin (2a) are clarified. Chemical support for the mechanism of formation of this novel demethylation product of quassin (1a) is provided, which together with the recent X-ray diffraction study of bisnorquassin m-bromobenzoate (2d) offers an independent corroboration of the structure and stereochemistry of 1a deduced by Valenta.
Esterification of ε-N-carbobenzoxy-L-lysine with boron trifluoride – alcohol
Authors: Coggins John. , Demayo Ruth , Benoiton N. Leo.
Published: May 2006

The esterification of ε-N-carbobenzoxy-L-lysine with various boron trifluoride – alcohol mixtures at 80 °C leads to some deprotection, which increases as the chain length of the alcohol increases. A convenient synthesis of ε-N-carbobenzoxy-L-lysine methyl ester in 58% yield from ε-N-carbobenzoxy-L-lysine and boron trifluoride – methanol has been developed.
Chlorination of some indole derivatives with ethyl N,N-dichlorocarbamate
Authors: Muchowski J. M.
Published: May 2006

The sole product obtained from the reaction of indole-2-carboxylic acid and ethyl N,N-dichlorocarbamate was 3,3,5-trichlorooxindole (7). In contrast, methyl indole-2-carboxylate gave a mixture of methyl-3,5-dichlorooxindole-3-carboxylate (10) and methyl-3,5,7-trichlorooxindole-3-carboxylate (11), the same products as obtained from the chlorination of methyl indole-3-carboxylate. The structures of these products were confirmed by degradation to known compounds and/or by synthesis, and mechanisms for their formation were suggested.
Studies of specifically fluoridated carbohydrates. Part V. Derivatives of 3,6-anhydro-5-deoxy-5-fluoro-1,2-O-isopropylidene-α-L-idofuraeose
Authors: Hall L. D. , Steiner P. R.
Published: May 2006

The facile synthesis of 3,6-anhydro-5-deoxy-5-fluoro-1,2-O-isopropylidene-α-L-idofuranose (4) from readily available precursors is described. The 1H and 19F nuclear magnetic resonance spectra of this derivative have been analyzed. Interestingly, the fluorine substituent exhibits detectable spin coupling with all ring protons except H-2. Both of the anomeric 1,2-di-O-acetyl derivatives of (4) have also been studied.
Molecular motion in solid complexes of trimethylamine with boron trihalides and borane
Authors: Yim C. T. , Gilson D. F. R.
Published: May 2006

Wide line nuclear magnetic resonance studies of trimethylamine complexes of BF3, BCl3, BBr3, and BH3 show that rotation of methyl groups and rotation about the B—N axes occur in the solid phases. The complex between ammonia and boron trifluoride has also been studied.
Ion neutralization reactions in irradiated hydrogen chloride, hydrogen bromide, and nitrous oxide
Authors: Wilson D. E. , Armstrong D. A.
Published: May 2006

Rates of ion neutralization have been measured in hydrogen chloride, hydrogen bromide, and nitrous oxide by collecting the ions remaining in a defined volume at various times after ionization by a pulse of 120 k.v.p. X-rays. Values of the total homogeneous ion-ion recombination coefficient, a, have been obtained for each gas over a range of pressures in the region 50 to 650 Torr. From a study of the effects of pressure and ion density, the relative rates of wall diffusion, mutual neutralization, and three-body neutralization have been deduced.
Some indoleninyl hydroperoxides
Authors: Kesswani H. I.
Published: May 2006

Exposure of 2,3-dimethyl-4-carbethoxy-7-ethylindole (1) and 2,3,5,7-tetramethylindole (5) to air yielded the corresponding indoleninyl hydroperoxides, 2 and 6 respectively. The decomposition of 2 under various conditions yielded o-acylaminoketone (3).
Non-Chugaev products from the pyrolysis of S-p-bromophenacyl xanthates of primary alcohols
Authors: Gilman R. E. , Henion J. D. , Shakshooki S. , Patterson J. I. H. , Bogdanowicz M. J. , Griffith R. J. , Harrington D. E. , Crandall R. K. , Finley K. T.
Published: May 2006

The study of the pyrolysis of S-p-bromophenacyl xanthates of 1-hexanol, cyclohexanemethanol, and 2-phenylethanol are reported. The complex reaction mixtures were found to be composed of carbonyl sulfide, carbon disulfide, the corresponding alkenes, alkyl bromides, and starting alcohols, and 4′-bromo-acetophenone. The formation of the non-Chugaev products in significant amounts indicates that these pyrolyses are quite different from the cis-elimination that is characteristic of S-methyl xanthates. The occurrence of the alkyl bromides is particularly significant. Possible mechanisms for the formation of all of these products are discussed.
Titanium tetrachloride promoted conversion of carboxylic acids to carboxamides
Authors: Wilson James D. , Weingarten Harold
Published: May 2006

In the presence of approximately stoichiometric amounts of TiCl4, carboxylic acids and amines react at room temperature and atmospheric pressure to form carboxamides in good yields. The mono- and diformyl derivatives of 1,2-dimethylhydrazine exhibit unusual nuclear magnetic resonance spectra which are briefly discussed.
Free-radical and molecular processes in the pyrolysis of ethylbenzene
Authors: Clark W. D. , Price S. J.
Published: May 2006

From 910 to 1089°K, at pressures of 20 to 36 mm, the pyrolysis of ethylbenzene in a toluene carrier flow system occurs primarily by three reactions[Formula: see text]The Arrhenius equation for the reaction [1], log k1 (s−1) = 14.7 − (70 100/2.3RT), is in agreement with a previous aniline carrier study and with thermochemical calculations. Reaction [11] is surface dependent and yields widely scattered results. For experiments in a conditioned quartz vessel, log k11 (s−1) = 9.06 − (51 700/2.3RT). Values of k1and k12 are unaffected by the nature of the surface and by changes in the surface-to-volume ratio. The rate constants for reaction [12] are somewhat scattered, but yield the approximate equation log k12 (s−1) = 12.7 − (64 000/2.3RT).E1 should possibly be increased by about 1 kcal to allow for the effect of reaction [−1], the recombination of methyl and benzyl species.
Infrared spectra and structure of methane – noble gas mixed crystals: the influence of temperature and methane concentration on the v3 vibration band of methane
Authors: Chamberland A. , Belzile R. , Cabana A.
Published: May 2006

The infrared spectra of CH4, at low concentrations in the noble gases, were obtained at temperatures ranging from 4°K up to the respective boiling points of argon, krypton, or xenon. It is concluded from this study that methane occupies substitutional cavities in these lattices. Furthermore, it is established that the potential hindering the rotation of the molecules perturbs the higher rotational levels to a greater extent than the low lying levels.In a second series of experiments, the methane concentration was varied from 0.06 to 55% for krypton; narrower ranges were used for argon and xenon. The experimental results clearly demonstrate that the influence of the CH4 concentration is different for the three systems and that the fine structure does not result from molecular aggregation.The spectrum of 0.06% CD4 in solid krypton shows fine structure which confirms the rotational origin of the four components observed for CH4. The CD4 spectra previously published were complicated with additional lines that probably arose from the nonhomogeneity of the samples.
Vibrational frequency assignments of isotopically different forms of nitrate ion in ionic nitrate crystals
Authors: Brooker M. H. , Irish D. E.
Published: May 2006

Infrared and Raman spectra of powdered ionic nitrates contain low intensity vibrational bands which are assigned to isotopically different species. Bands at ~(ν1 − 20) and ~ (ν4 − 13) cm−1 are assigned to the 14N16O218O− ion whereas the band at ~ (ν2 − 20) cm−1 is assigned to the 15N16O3− ion. Failure of the ratio of band intensities to agree with predicted isotopic ratios is discussed.
Anodic oxidation of copper in alkaline solution
Authors: Dignam M. J. , Gibbs D. B.
Published: May 2006

The anodic formation of Cu2O on electropolished polycrystalline copper has been examined galvano-statically in a borate buffer solution over a range of current densities and temperatures. A model for film formation based on rapid formation of oxide nuclei followed by their lateral growth has been developed and shown to be in quantitative agreement with the data. According to this model, an oxygen-containing adsorbed intermediate, formed in an electrochemical step, reacts with metal at the peripheries of oxide patches to form more oxide. Both one- and two-dimensional lateral growth mechanisms were considered, the former being found to represent the data appreciably better. Assuming the initial electrochemical step to be [Formula: see text], where (OH)s represents the adsorbed intermediate, the first-order rate constant, kf calculated at the equilibrium electrode potential, is given by kf = 1013.3exp(−19 400/RT)s−1.
Complexes of stannic chloride and alkyl phenols and the influence of these complexes and of free phenol on the cationic polymerization of isobutene
Authors: Bauer R. F. , LaFlair R. T. , Russell K. E.
Published: May 2006

The polymerization of isobutene in ethyl chloride solution at −78.5 °C has been studied using stannic chloride as catalyst and alkyl substituted phenols as cocatalysts. In preliminary experiments, the nature and extent of the complexing between phenols and stannic chloride was examined and it was shown that σ-complexing occurs between the oxygen of the phenol and the stannic chloride. Equilibrium constants were determined over the temperature range 30 to −50 °C and were used, together with hydrogen bonding data, to estimate the concentrations of complex and free phenol in the polymerization mixtures at −78.5 °C. The active initiator in the polymerization is probably the σ-complex but the free phenol acts as a chain terminating agent. This explains the ability of the cocatalyst to decrease the rate of polymerization under some experimental conditions. For isobutene concentrations up to 3 M and at constant dielectric constant the rate of polymerization and the molecular weight are proportional to the monomer concentration. A mechanism is proposed to account for the main features of the experimental results.
Reactions of N-(2- and 4-methylsulfonylphenyl)hydroxylamines and 2-methylsulfonylnitrosobenzene in dilute aqueous sodium hydroxide solution
Authors: Shaw K. B. , Heggie R. M. , Miller R. K.
Published: May 2006

When N-(2-methylsulfonylphenyl)hydroxylamine (4) was treated with dilute sodium hydroxide solution the major product was always 2,2′-di(methylsulfonyl)azoxybenzene (5). At room temperature other significant products were 2-hydroxy-2′-methylsulfonylazoxybenzene (6a) and 2-methylsulfonylnitrobenzene (2), while 6a was also formed at reflux together with small amounts of 2-hydroxy-2′-methylsulfonylazobenzene (8), 2-methylsulfonylaniline (7), 3-methylsulfonyl-3′-nitro-4-amino-4′-hydroxybiphenyl (3), and 2. The compounds 5, 6a, and 7 were also obtained when 2-methylsulfonylnitrosobenzene (9) was boiled with alkali. The decomposition of N-(4-methylsulfonylphenyl)hydroxylamine (16) in dilute alkali at room temperature gave a quantitative yield of 4,4′-di(methylsulfonyl)azoxybenzene (17) and at reflux, mixtures of 17 and 4,4′-di(methylsulfonyl)azobenzene (18) were obtained. The modes of formation of the various products from the two hydroxylamines are discussed.
Reactions of iron pentacarbonyl with compounds containing the N—O linkage
Authors: Alper Howard , Edward J. T.
Published: May 2006

Amine oxides, azoxybenzenes, and nitrones are deoxygenated in good yields by iron pentacarbonyl in hot butyl ether. Substituted nitro- and nitrosobenzenes are reduced under these conditions to azo and/or amino compounds, depending on the nature and location of the substituents; some evidence for nitrene or nitrene-like intermediates in these reactions is presented.
Pulse radiolysis of ethanol
Authors: Fletcher J. W. , Richards P. J. , Seddon W. A.
Published: May 2006

The radiation chemistry of ethanol has been investigated by pulse radiolysis with emphasis on the decay kinetics and yield of the solvated electron, e−EtOH, in neutral and alkaline solution. Computer calculations show that the experimental data are most consistent with a yield G(e−EtOH) = 1.7 molecules/100 eV, and a pseudo first-order half life for e−EtOH, [Formula: see text] which corresponds to a second-order rate constant k(e− + EtOH) = 7 × 103 M−1 s−1.Rates of reaction of the electron with acetaldehyde and C6F12 have been determined to be 4.0 ± 0.5 × 109 and 2.5 ± 0.5 × 109 M−1 s−1, respectively.The empirical square root formula for spur scavenging kinetics[Formula: see text]is obeyed for scavenging of the radiation produced positive ion.
Oxidation products of 2,3,6,7-tetramethoxy-9,10-dimethylphenanthrene
Authors: Edwards J. M. , Weiss Ulrich
Published: May 2006

Depending upon the conditions of solvent and temperature, oxidation of the readily accessible 2,3,6,7-tetramethoxy-9,10-dimethylphenanthrene (3) with Na2Cr2O7 gave 2,3,6,7-tetramethoxyphenanthrene-9,10-dicarboxylic acid anhydride (1), 2,2′-diacetyl-4,4′,5,5′-tetramethoxybiphenyl (4), or the new aldehyde 5. Compounds 1 and 4 have been obtained previously only by oxidative degradation of the alkaloid tylophorine (2); their ready availability may be of value for the synthesis of pharmacologically active compounds related to 2.
Total synthesis of DL-glucose
Authors: Singh U. P. , Brown R. K.
Published: May 2006

The stereoselective synthesis of DL-glucose has been accomplished in 34% overall yield starting from 1,6:2,3-dianhydro-4-dexoy-β-DL-ribo-hexopyranose (1), a compound obtainable from the Diels–Alder condensation of acrolein.
Photocyclization reactions of aryl polyenes. The photocychzation of 1-substitutedphenyl-4-phenyl-1,3-butadienes
Authors: Leznoff Clifford C. , Hayward Roger J.
Published: May 2006

Irradiation of 1-p-substitutedphenyl-4-phenyl-1,3-butadienes gave mixtures of 1-p-substituted-phenylnaphthalenes and 7-substituted-1-phenylnaphthalenes. Photocyclization of 1-m-substituted-phenyl-4-phenyl-1,3-butadienes gave 1-m-substitutedphenylnaphthalenes, 6-substituted-1-phenylnaphthalenes, and 8-substituted-1-phenylnaphthalenes. Characterization of the photoproducts was achieved through synthesis by an independent method.
Alkali metal adducts of benzophenone azine. I. The sodium and potassium adducts
Authors: MacPherson E. J. , Smith James G.
Published: May 2006

Contrary to previous reports, the reaction between benzophenone azine and sodium or potassium produces an adduct containing 2 g-atoms of alkali metal per mole of azine. The chemical reactions of this dianion have been examined and a 1,2-dianionic structure is most consistent with its chemical behavior.Treatment of the adduct with methyl iodide, 1,3-dibromopropane, or 1,4-dibromobutane results in alkylation on the benzylic carbon and adjacent nitrogen. However, regeneration of benzophenone azine occurred with methylene iodide, 1,2-dibromoethane, and benzyl chloride.With ethyl chloroformate, reaction occurred at the carbanionic center to form an intermediate unstable anion. This anion could be protonated or alkylated but if allowed to stand, decomposed to diphenyldiazomethane and the anion of ethyl diphenylacetate.Reaction of the benzophenone azine dianion with methyl benzoate is quite complicated and leads to substantial amounts of benzophenone azine being regenerated by electron transfer. That portion of the dianion which is not converted to azine reacts with methyl benzoate to produce the anion of α-benzamido- α,α-diphenylacetophenone.The possibility that an adduct of N-benzoyl benzophenone imine is an intermediate in this last reaction is examined and rejected.
Reaction of dialkyl phosphonates with hexafluoroacetone
Authors: Janzen A. F. , Pollitt R.
Published: May 2006

The reaction of dialkyl phosphonates, (RO)2P(O)H where R = CH3, C2H5, and n-C4H9, with hexafluoroacetone gives, in each case, two isomeric products, (RO)2P(O)OCH(CF3)2 and (RO)2P(O)C(OH)-(CF3)2. Products are characterized by elemental analyses, infrared, proton and fluorine nuclear magnetic resonance, and mass spectrometry. The relative yield of isomer depends markedly on the alkyl group present. These results are explained in terms of an inductive effect on the polarity of the P—H bond which influences the direction of addition of hexafluoroacetone.
Studies on some 4,5-diacyl-1,3-dithioles
Authors: Ahmed M. , Buchshriber J. M. , McKinnon D. M.
Published: May 2006

1,2-Dithiole-3-thiones and 1,2,4-dithiazole-3-thiones react with dibenzoylacetylene to provide thioacylmethylene or thioacylimino-1,3-dithiole adducts respectively. Some of these, on sulfurization, provide thieno[3,4d]-1,3-dithiole derivatives, but in others a retro-1,3-dipolar reaction predominates. Further reaction of the initial adducts with more dibenzoylacetylene provides spiran compounds.
Transition state volumes and solvolysis mechanisms
Authors: Mackinnon MOYRA J. , Lateef A. B. , Hyne J. B.
Published: May 2006

The transition state partial molal volume behavior, [Formula: see text] as a function of binary solvent composition was obtained for three reactions by dissection of the activation volume, ΔV*, into initial and transition state components: [Formula: see text] The solvolyses of t-butyl chloride, benzyl chloride, and p-chlorobenzyl chloride represented a gradation of reaction type between SN1 and SN2 and the transition state partial molal volume behavior was found to be distinctly different in each case and in agreement with the mechanistic classification of these reactions.
Ultrasonic absorption in the water–2-isobutoxyethanol system
Authors: Fanning R. J. , Kruus P.
Published: May 2006

Ultrasonic absorption measurements have been carried out on the system 2-isobutoxyethanol–water as a function of composition, temperature, and frequency. The composition and frequency dependence of the absorption show the same general type of behavior as for previously investigated critical binary liquid systems and for alcohol–water systems. The temperature dependence shows a behavior opposite to that for the other systems at the frequency where it was studied in detail. At the lowest experimentally available frequency, however, the temperature dependence is somewhat similar to that in other critical binary liquid systems. Ultrasonic absorption measurements are also reported for water at small temperature intervals. No anomalous behavior in the temperature range 0 to 30 °C is observed.
The reaction of 2-butyne with hydrogen catalyzed by nickel, copper, cobalt, iron, and nickel–copper alloys
Authors: Mann R. S. , Khulbe C. P.
Published: May 2006

The reaction between hydrogen and 2-butyne over unsupported nickel, copper, cobalt, iron, and nickel–copper alloys has been investigated in a static constant volume system between 30 and 250 °C for a wide range of reactant ratios. The reaction over metals and their alloys is simple hydrogenation, the early stages being principally a selective production of cis-2-butene with small yields of polymers. The order of reaction with respect to hydrogen was one and independent of temperature. While the order of reaction over cobalt and copper with respect to 2-butyne was zero, it was slightly negative and temperature dependent for nickel and nickel–copper alloys. The selectivity was independent of initial hydrogen pressure for nickel, cobalt, copper and most of the nickel–copper alloys. The overall activation energy for nickel, cobalt, and copper were 9.1, 6.6, 33.5 kcal/mole, respectively. Selectivity and extent of polymerization increased with increasing amounts of copper in the nickel–copper alloy.
Nucleophilic substitution of vinylic halogens in 3-halomethacrylonitriles. Some observations on olefin stabilities
Authors: Gardner D. V. , McGreer D. E.
Published: May 2006

3-Chloro- and 3-bromomethacrylonitrile (E- and Z-) have been shown to undergo nucleophilic substitution at C-3 with > 95% retention of configuration. The configuration of each product has been established by the use of nuclear magnetic resonance spectroscopy. The thermodynamic position of equilibrium for each pair of E–Z isomers has been determined and the factors which affect this equilibrium are discussed. Some form of cis interactions, non-steric in origin, dominates in determining the equilibrium positions.
Influence of steric and polar effects in determining the equilibrium position for cis–trans-olefin pairs
Authors: Gardner D. V. , McGreer D. E.
Published: May 2006

A series of α,β-unsaturated nitriles and esters substituted by t-butyl or isopropyl groups at the β-position along with methoxyl, thioethoxyl dimethylamino, chloro, and hydrogen at the other β-position have been prepared. Evaluation of the isomer stability from cis-trans equilibrations achieved catalytically or thermally supports earlier observations'that steric and polar factors maintain a strong tendency for a β-methoxyl group to be trans to a nitrile or carbomethoxy group even when opposed by a t-butyl group. The tendency for a chloro group to prefer to be trans to a carbomethoxy group in methyl β-chlorocrotonate is overcome by replacing the β-methyl by isopropyl or t-butyl.
Solvent effect on the conformational preference of the carbanions derived from benzyl methyl sulfoxide
Authors: Durst T. , Fraser R. R. , McClory M. R. , Swingle R. B. , Viau R. , Wigfield Y. Y.
Published: May 2006

The effect of solvent on the stereochemical course of deuteration of benzyl methyl sulfoxide has been studied by two methods. In the first, the relative rates of exchange of the diastereotopic methylene protons were found to vary from 14:1 (D2O/NaOD) to 0.5:1 (t-butanol-OD/NaO-t-butyl). Experiments on quenching α-lithiobenzyl methyl sulfoxide with D2O gave the same diastereomers in ratios ranging from 1.7:1 (DMSO) to 0.065:1 (THF). The significance of these findings in relation to previous work on conformational stabilities of α-sulfinyl carbanions is discussed.
The radioactive decay series 138Nd → 138Pr → 138Ce
Authors: Hogan James J.
Published: May 2006

Measurements of the energies and intensities of gamma rays associated with decay of 138Nd, 138Prm, and 138Prg have been performed using a Ge(Li) detector. The branching ratio to a previously unreported excited level of 138Pr (328.1 keV) has been measured, thus allowing for direct measurement of the decay of 138Nd. Half-lives of 2.20 ± 0.07 and 5.04 ± 0.09 h have been measured for 138Prm and 138Nd, respectively. Decay schemes for 138Prm → 138Ce and for the decay chain 138Nd → 138Prg → 138Ce are proposed.
Photoconductivity of γ-irradiated methyltetrahydrofuran glass at 77 °K
Authors: Baverstock K. F. , Dyne P. J.
Published: May 2006

γ-Irradiated glasses of methyltetrahydrofuran at 77 °K exhibit photoconductivity on illumination with visible light. A variety of kinetic effects are observed as the wavelength of the exciting light is changed from blue to the near infrared. It is suggested that, due to the coulombic field of the positive ions in the glass, some electrons can be released by red light while others can be released only by blue light. A thermally unstable red sensitive center can also be formed in the glass during illumination with blue light. This unstable center could be a dielectron.
Spectrofluorometric studies. IX. Fluorescent and triplet yields of the tetrafluorobenzenes excited in the 2600 Å region
Authors: Scholz B. H. , Unger I.
Published: May 2006

The gas phase fluorescent and triplet yields of 1,2,4,5-, 1,2,3,4-, and 1,2,3,5-tetrafluorobenzene (TFB) excited in the 2600 Å region have been determined. For 1,2,4,5-TFB, the maximum fluorescent yield (Φf = 0.338) occurs at λex = 2670 Å and the triplet yield at this wavelength = 0.515. For 1,2,3,4-TFB, the maximum fluorescent yield is 0.186 and is obtained at λex = 2645 Å; the triplet yield at this wavelength = 0.220. For 1,2,3,5-TFB the maximum fluorescent yield = 0.029 and the maximum triplet yield is 0.141, at an exciting wavelength of 2680 Å. The fluorescent and triplet yields of the three molecules, at any exciting wavelength studied, are not quenched by the addition of cis-butene-2 (c-B-2).
Protonation of conjugated carbonyl groups in sulfuric acid solutions. III. α,β-Unsaturated ketosteroids
Authors: Zalewski R. I. , Dunn G. E.
Published: May 2006

Protonation of 20 α,β-unsaturated ketosteroids by sulfuric acid was studied by ultraviolet spectrophotometry. Plots of log [B]/[BH+] from spectral data against the amide acidity function, HA, gave straight lines with unit slope. The pKBH+ values thus obtained show the same additive effects of substituents as that reported previously for simple α,β-unsaturated alicyclic ketones.
Radiolysis of aqueous 2,2,2-tribromoethanol solutions
Authors: Sorensen V. G. , Bhale V. M. , McCallum K. J. , Woods R. J.
Published: May 2006

Hydrogen bromide, glycolic acid, and carbon dioxide have been identified as products of the γ-radiolysis of aqueous 2,2,2-tribromoethanol solutions. The effect of oxygen, tribromoethanol concentration, and dose rate upon the yields of bromide ion and acid have been determined, and partial radiolysis mechanisms are proposed for reaction in the presence and absence of oxygen. Dibromoacetaldehyde, reported to be a product of the photochemical decomposition of tribromoethanol solutions, was not detected in the radiolysis experiments or in tribromoethanol solutions exposed to sunlight.
Free-energy relationships in coordination chemistry. I. Linear relationships among equilibrium constants
Authors: Nieboer E. , McBryde W. A. E.
Published: May 2006

After a review of previous semi-empirical free-energy relationships applying to the formation of metal complexes, the following equations are derived within a framework of logical assumptions[Formula: see text]These compare stability constants of complexes formed by a metal ion M and a ligand L with those formed by a reference metal Ms and a reference ligand Lo. The derivation of these equations reveals an inherent relationship between the constants B and C, which is formulated through an "exactness" test. The application of these relationships to stoichiometric equilibrium constants is discussed.In the testing of the foregoing equations with data for various ligand families reacting with numerous metal ions, two principal modes of behavior were noted. In one, there was a mutual dependence of B on the particular metal ions compared and of C on the particular ligands compared. In the other, all values of B and C were found to equal unity irrespective of metal ion or ligand compared. The cause of this distinction is not yet understood.
The 3A2 state of thiocarbonyl difluoride
Authors: Moule D. C.
Published: May 2006

The 4500 Å band system of thiocarbonyl difluoride F2CS has been photographed under conditions of moderately high resolution and has been assigned to the activity of the v1, v2, v3, and v4 modes arising from the 3A2 ← 1A1 electronic transition. The out-of-plane wagging levels were found to be strongly anharmonic, the observed inversion doubling indicating that the maximum in the potential function was greater than 3100 cm−1.
A wide line nuclear magnetic resonance study of molecular motion in pyridinium salts
Authors: Matthews C. H. , Gilson D. F. R.
Published: May 2006

Wide line nuclear magnetic resonance studies of pyridinium hexafluorophosphate, chloride, and nitrate show line width and second moment transitions which are attributed to reorientational motions of the pyridinium ring. The differences in transition temperatures are due to the different hydrogen bonded structures in the three salts.
The radiation-induced oxidation of ethanol and methanol by hydrogen peroxide in aqueous solution
Authors: Burchill C. E. , Ginns I. S.
Published: May 2006

The radiation-induced chain oxidation of ethanol and methanol by hydrogen peroxide in deaerated aqueous solutions has been investigated. In each case the alcohol is oxidized to the corresponding aldehyde and hydrogen peroxide is reduced in equivalent yield. With ethanol as the oxidizable substrate the yields are independent of peroxide concentration in the range 5 × 10−2 to 5 × 10−3 M and linearly dependent on ethanol concentration in the range 0.085 to 0.85 M. In contrast, the oxidation of methanol is first order in hydrogen peroxide, independent of methanol concentration up to 2.0 M and shows a simple square root dependence on dose rate. The differences are explained by consideration of the participation of two different radicals derived from ethanol, CH3ĊHOH and ĊH2CH2OH, whereas only one radical, ĊH2OH, is formed from methanol.
Computer study of Br2 shock wave dissociation
Authors: Ip J. K. K. , Burns George
Published: May 2006

Computational studies of Br2 shock wave dissociation in argon were conducted, and the possibility of vibrational relaxation–dissociation coupling, stronger than previously suspected (2), was investigated. In order for such a coupling to occur, the vibrational temperature in the lower vibrational levels of Br2 must be lower than that in the higher vibrational levels. The approximate shapes of vibrational distribution functions were obtained, and corresponding shock wave profiles were computed. The calculations predict an appreciable difference between the translational and vibrational temperatures of the dissociating Br2. In order to check this conclusion, the Br2 absorption coefficients at 440 mμ, measured at equilibrium by heating Br2 in a furnace from 300 to 1250°K, were compared to the absorption coefficients measured in shock waves.
The limiting high-pressure rate constant for the thermal isomerization of methyl isocyanide
Authors: Yip C. K. , Pritchard H. O.
Published: May 2006

The rate of the thermal isomerization of methyl isocyanide is reduced by about 20% when the system is pressurized with 100 atm of propane, but is unaffected when the system is pressurized with carbon dioxide. It is suggested that these observations can be explained by the presence of a concurrent free-radical catalyzed isomerization.
Quantitative investigation of the ozonolysis reaction. XIV. A simple carbonium ion stabilization approach to the ozone cleavage of unsymmetrical olefins
Authors: Fliszár Sándor , Renard Jean
Published: May 2006

The direction of ozone cleavage of selected unsymmetrical olefins R1R2C=CR3R4 to give (a) R1R2CO + R3R4C+OO− and (b) R1R2C+OO− + R3R4CO has been measured, with particular emphasis on the mode of participation of alkyl substituents in distributing the reaction paths a and b. The interpretation, in terms of substituent effects in stabilizing potential zwitterionic carbo-cations in the transition states corresponding to paths a and b, considers (i) the "hyperconjugative stabilization" of positive sites, where the stabilizing abilities of the substituents are in the order CH3 > C2H5 > i-C3H7 > tert-C4H9, and (ii) the participation of inductive effects. The latter appear to be particularly important when the substituents on the two C atoms of the primary ozonide act in the same direction in favoring its electrocyclic cleavage. In the ozonolysis of monosubstituted ethylenes the inductive effects are predominant, i.e. the R—C+HOO− formation is favored by the R groups in the order tert-C4H9 > i-C3H7 > C2H5 > CH3, whereas in trans- and cis-1,2-disubstituted ethylenes "hyperconjugation" governs the direction of cleavage. The cleavage of selected 1,1-disubstituted, tri-, and tetrasubstituted ethylenes is also studied.
Infrared spectrum of HDO in aqueous solutions of perchlorates and tetrafluoroborates
Authors: Brink George , Falk Michael
Published: May 2006

The OH and OD stretching bands of HDO in aqueous solutions containing the ions ClO4− and BF4− are split into two components. The high-frequency component, A, does not shift with temperature. It is interpreted as due to OH groups involved in weak [Formula: see text] or [Formula: see text] hydrogen bonds. This interpretation is in line with the corresponding OH frequencies of other systems containing ClO4− ions, such as methanolic solutions and crystalline hydrates. Solvent-separated ion pairs may account for the observed cation effect on band A. The low-frequency component, B, varies with temperature almost exactly like the corresponding band of pure water. It is interpreted to be due to those OH groups which are not associated with the anion. Components A and B are not resolved in solutions of most electrolytes because the distribution of strengths of interactions of OH groups with most anions overlaps that of [Formula: see text] interactions between water molecules.
Acenaphthene I. The preparation of derivatives of 4,5-diamino naphthalic anhydride
Authors: Jones Louis A. , Joyner Charles T. , Kim Hong Ki , Kyff Robert A.
Published: May 2006

The preparation of 5-nitroacenaphthene (2) using several nitrating agents resulted in a product which was found to be contaminated with 20–30% of the 3-nitro isomeride. Separation was accomplished by t.l.c. and the n.m.r. spectra of the isomers are now reported. A new synthesis of 4,5-dinitronaphthalic anhydride (5) and an improved preparation of the dimethyl and diethyl esters of 4-nitronaphthalic anhydride and 5 is described. The esters were converted to the corresponding diamino derivatives by high pressure hydrogen–Pd reduction.
Cyanoethylations and Michael additions. IV. The synthesis of allylic cyclohexenols by γ-cyanoethylation of α, β-unsaturated aldehydes and ketones. Part IV
Authors: Engel Ch. R. , Ruest L.
Published: May 2006

The cyclo-γ-cyanoethylation of 3β-acetoxy-D-homo-5α-pregn-17a-en-21-al is reported. It is shown that the orientation of the cyanoethylation of 2-cycloalkyl-substituted ethenals does not significantly depend on the ring size of the cycloalkyl substituent. It is further shown that the stereochemistry of the cyclohexadienonitrile obtained by dehydration of the main reaction products seems to be, in the case of a fusion to a six-membered ring, in agreement with Moscowitz' rule relating the helicity of the chromophore to the sign of its Cotton effect, in contradistinction to the situation in the case of a system in which one of the double bonds of the chromophore is exocyclic to a five-membered ring.
Cu2+ – fulvic acid chelation equilibrium in 0.1 m KCl at 25.0 °C
Authors: Gamble Donald S. , Schnitzer M. , Hoffman I.
Published: May 2006

Cu2+ reacts with fulvic acid to form a site-bound chelate on the fulvic acid polymer molecules. It is deduced from literature evidence that this chelate is the same type that Cu2+ forms with salicylic acid. This is supported by a Job's continuous variations plot. The mass action quotient for the chelate formation in 0.1 m KCl at 25.0 °C has been measured as a function of the degree of ionization of the chelating carboxyl groups. The strength of the Cu2+ – fulvic acid chelate is comparable to that of other bidentate Cu2+ chelates.