bluuebunny/crossref_metadata_2025 huggingface dataset:
A Study of the Decomposition of Sodium Azide using Differential Thermal Analysis
Authors: Potvin H. , Back M. H.
Published: May 2006

Differential thermal analysis and thermogravimetric analysis of sodium azide diluted with sodium chloride both show one major peak followed by a second minor one. This is interpreted as indicating the occurrence of two distinct decomposition processes. The activation energy of the first, major process was 36 kcal/mol, which agrees with values reported previously from measurements of the rate of nitrogen evolution. Differential thermal analysis of sodium azide mixed with alumina was complicated by the presence of variable amounts of water adsorbed on the alumina. The presence of water was shown to have an inhibiting effect on the decomposition.
Production of Vibrationally Excited Carbon Monoxide by the Reaction of Oxygen Atoms with Acetylene, Methylacetylene, and Methane
Authors: Arnold S. J. , Kimbell G. H.
Published: May 2006

Infrared chemiluminescence attributed to the first overtone of CO was observed when either C2H2 or was introduced into a stream of oxygen which had been passed through a microwave discharge. The addition of vibrationally cold CO to these systems was found to produce a vibrational population inversion in the chemically formed CO. CO first overtone emission was not observed when CH4 was introduced into a similar stream of oxygen unless the CH4 had been subjected to a microwave discharge. These observations are used to clarify the mechanisms governing the formation of CO in continuous wave air–helium–hydrocarbon electrical discharge lasers.
Lignans of Western Red Cedar (Thuja plicata Donn). XI. β-Apoplicatitoxin
Authors: MacDonald Bruce F. , Barton G. M.
Published: May 2006

The structure of the eleventh in the series of novel lignans from the heartwood of western red cedar (Thuja plicata Donn) has been determined as 1,4-dihydronaphthalene-6-hydroxyl-2-(hydroxymethyl)-7-methoxy-4(3′,4′-dihydroxy-5′-methoxyphenyl)-3-carboxylic acid lactone (β-apoplicatitoxin) (1) by spectrometric methods and by aromatization to the known compound trimethylplicatinaphthalene. This lignan provides an intermediate to the possible stereoselective synthesis of derivatives related to the picropodophyllin series.
Heterogeneous Interactions of Methylamines on Porous Adsorbents. Part III. The Adsorption Characteristics of Methylamines on γ-alumina and Types '3A' and '13X' 'Molecular Sieves'
Authors: Cook Walter George , Ross Robert Anderson
Published: May 2006

The adsorption characteristics of mono-, di-, and trimethylamine on γ-alumina have been investigated and adsorption isotherms in the regions of their boiling points determined, along with isothermal calorimetric heats of adsorption up to monolayer coverage (θ = 1). From the initial heats of adsorption of 21.6 to 32.4 kcal/mol θ = 0.05, and the strong retention of the amines adsorbed at low pressures, chemisorption is considered to occur at θ < 0.20. The maxima and minima displayed in the heat curves are discussed in terms of adsorbate–adsorbate interactions at sub-monolayer coverage levels. Adsorption isotherms for di-and tri-methylamine on Linde 'molecular sieves' '13X' and '3A' have been measured also, along with the trimethylamine heat curves for these materials.
Analysis of the Visual Spectrum of Methyl Orange in Solvents and in Hydrophobic Binding Sites
Authors: Reeves Richard L. , Kaiser Robert S. , Maggio Mary S. , Sylvestre Edward A. , Lawton William H.
Published: May 2006

The absorption curves of methyl orange (MO) and analogous p-aminophenylazobenzenes in organic and aqueous organic solvents are shown to consist of two severely overlapping bands. The curves have been resolved into two skewed component bands using a regression method. The blue shift of the absorption maximum obtained when organic solvents are added to aqueous solutions of MO, or when MO is bound to bovine serum albumin or a surfactant micelle, is the result of a change in relative intensities of the component bands. The low-frequency component is assigned to a π1 → π1* transition of a solvate in which there is specific hydrogen-bonding interaction between solvent and the azo nitrogens, and the high-frequency component to a π1 → π1* transition of a solvate in which the interaction is absent. The low-frequency component is favored by aqueous solvent compositions and by low temperatures. The free energies of interconversion of the species in various hydrogen-bonding solvents are correlated by the solvent surface tension but not by the dielectric constant. The results show that the shift in absorption maximum accompanying binding to a protein or micelle should be interpreted as a shift in an equilibrium rather than as a shift in transition energy.
Investigations of Substituent Effects by Nuclear Magnetic Resonance Spectroscopy and All-valence Electron Molecular Orbital Calculations. I, 4-Substituted Styrenes
Authors: Hamer Gordon K. , Peat Ian R. , Reynolds William F.
Published: May 2006

1H and 13C chemical shifts have been determined for over 20 4-substituted styrenes under conditions corresponding to infinite dilution in a non-polar medium. Correlations of the internal chemical shift difference for the β vinyl protons, Δδ(B − C) with electric field components estimated by a classical electrostatic calculation, with the field parameter F, and with hydrogen charge densities estimated by CNDO/2 MO calculations provide conclusive evidence for the existence of a through-space field effect. CNDO/2 calculations for 4-substituted 1-vinylbicyclo[2.2.2]octanes and ethylene–methylX pairs indicate that this through-space field effect has a geometric dependence similar to that predicted by the Buckingham equation.Correlations of vinyl 1H and 13C chemical shifts and charge densities with field, F, and resonance, R, parameters provide a self-consistent picture of electronic effects in these compounds. 1H chemical shifts for some derivatives are affected by magnetic effects but this does not obscure the overall pattern of electronic effects. This pattern of electronic effects can be completely accounted for by a model which assumes that substituent effects can be transmitted through space (field effects), via conjugative interactions (resonance effects) or by polarization of the styrene π electron system by the polar C—X bond (π polarization effects). The latter effect appears to be more important than previously realized.1H correlations with F and R are used to estimate self-consistent and apparently reasonable Δχ values for C≡N and C≡C—H groups and F and R values for carbonyl substituents and (CH3)3M substituents (M = Si, Ge, Sn, and Pb). The halogens give anomalous results. A comparison of various correlations suggests that these anomalies are magnetic in origin.
A Low Temperature Infrared Study on the Association of Thiols with Pyridine and Triethylamine
Authors: Alencastro R. Bicca De , Sandorfy C.
Published: May 2006

The infrared spectra of solutions containing propane-1-thiol or benzenethiol as proton donors, and pyridine or triethylamine as proton acceptors were measured down to about −100 °C. The dependence of hydrogen bond formation on concentration and temperature was studied at the fundamental and overtone region of the S—H stretching vibration. The predominant species is found to be a 1:1 [Formula: see text] type complex. In addition, evidence was found for the existence of more highly associated species at low temperatures. Thiol–thiol [Formula: see text] type hydrogen bonds are also present in the case of benzenethiol–pyridine mixtures.
Matairesinol-4,4′-di-O-β-D-glucopyranoside from Trachelospermum asiaticum var. intermedium
Authors: Nishibe Sansei , Hisada Sueo , Inagaki Isao
Published: May 2006

A new lignan diglucoside was isolated from the stems of Trachelospermum asiaticum Nakai var. intermedium Nakai (Apocynaceae) and the structure has been determined as matairesinol-4,4′-di-O-β-D-glucopyranoside (1).
Constituents of Solidago Species. Part III. The Constitution of Diterpenoids from Solidago juncea Ait.
Authors: Henderson M. S. , Murray R. D. H. , McCrindle R. , McMaster D.
Published: May 2006

The constitution and stereochemistry of five new diterpenoids from Solidago juncea Ait., junceic acid (3a), the related epoxide (6a), junceanol W(4a), junceanol X (4b), and junceanol Y (5a), have been assigned on the basis of their chemical and spectroscopic properties. Of key importance in these deductions have been the transformations of 4b and 5a into the previously described hydrocarbon 19 and of 3a into 3e. Two known diterpenoids, (−)-hardwickiic acid (2a), which has also been converted into 3e, and ent-16-kauren-19-oic acid (1), are further constituents of S. juncea.
The Synthesis of Some Analogs of the Hallucinogen 1-(2,5-Dimethoxy-4-methylphenyl)-2-aminopropane (DOM)
Authors: Coutts Ronald T. , Malicky Jerry L.
Published: May 2006

The synthesis of a series of 4-substituted 1-(2,5-dimethoxyphenyl)-2-aminopropanes, in which the 4-substituent is Br, Cl, I, NO2, NH2, and NHAc, is described. These compounds are analogs of 1-(2,5-dimethoxy-4-methylphenyl)-2-aminopropane (DOM), a known hallucinogen. A synthesis of N-(2,5-dimethoxy-4-methylphenethyl)hydroxylamine, the N-hydroxy homolog of DOM, is also reported. Brief reference is made to the preliminary pharmacology of these compounds.
A Facile Reduction of Sulfones to Sulfides
Authors: Gardner J. N. , Kaiser S. , Krubiner A. , Lucas H.
Published: May 2006

Diisobutylaluminum hydride is shown to be an effective reagent for the reduction of sulfones to sulfides. Yields as high as 70% are obtained in this normally difficult reduction. A technique for the easy isolation from the reaction mixture of volatile sulfides is described.
Theory of Molecular Size Distribution in Multichain Polymers: Condensation of R—Af with R′—Bf′, and R—Af with R′—Af′
Authors: Whiteway S. G. , Smith I. B. , Masson C. R.
Published: May 2006

Expressions are derived for the mole fractions of various oligomers formed by condensation of the monomer R—Af with the monomer R′—Bf′. It is assumed that A groups can react only with B groups and that intramolecular condensation may be neglected. The results, for cases where comparison is possible, agree with those derived previously for the self-condensation of R—Af. In addition, expressions are derived for the condensation of R—Af with R′—Af′ where A groups react with one another.
Isotopic Studies of the Metal–Ligand Bond. Part III. The Far Infrared Spectra of Some Tetragonal Diamine Complexes of Cobalt(II) and Nickel(II): Studies of the Metal–Nitrogen Bond, as a Function of Metal Ion and of Spin State
Authors: Lever A. B. P. , Mantovani Elvio
Published: May 2006

The far infrared spectra of 35 complexes of the formula M(diamine)2X2 are reported where M = Co(II) and Ni(II), X = Cl−, Br−, I−, NO3−, SCN−, ClO4−, and AgI2− and the diamine is ethylenediamine or its N,N-symmetric or antisymmetrically substituted dimethyl or diethyl derivative. Isotopic substitution studies with 62Ni and with 2H are carried out with eleven characteristic complexes and assignments for the metal–nitrogen modes in both octahedral and square planar complexes so deduced. In most cases the appropriate number of metal–ligand modes, based on symmetry considerations, are observed. The variations in observed M—N frequencies are discussed in terms of the electronic and geometric factors previously utilized for the corresponding copper(II) complexes. In complexes containing the asymmetric ligands, stretching vibrations arising from the two types of metal–nitrogen bond can be separately identified. Isotopic studies of pairs of complexes containing the same ligand and metal ion but with the latter in alternate spin states are reported here for the first time. All of the cobalt(II) complexes and several of the nickel(II) complexes are reported here for the first time.
Scytalone (3,6,8-Trihydroxytetralone), a Metabolite from a Scytalidium Species
Authors: Findlay J. A. , Kwan D.
Published: May 2006

A metabolite from culture filtrates of a Scytalidium strain is shown by spectroscopic and chemical means to have structure 1a. The oxygenation pattern is as anticipated from a polyketide precursor.
Neighboring Group Participation in the Halogenation of Sulfoxides
Authors: Durst T. , Tin K.-C. , Marcil M. J. V.
Published: May 2006

PhS(O)(CH2)nCH2OH(n = 1–3) react with sulfuryl chloride at −78° or 0° in methylene chloride to give the corresponding PhSO2(CH2)nCH2Cl. Evidence is presented that cyclic alkoxyoxosulfonium salts are intermediates in these transformations. When n = 4 only chlorination α to the sulfoxide function was observed. The sulfinyl carboxylic acids PhS(O)(CH2)nCO2H (n = 1–3) and amides PhS(O)(CH2)nCONH2 (n = 1–3) were also reacted with SO2Cl2. α-Chlorination was observed for both compounds when n = 1 or 3. When n = 2 the products were the 3-phenylsulfonylpropionyl chloride and 3-phenyl-sulfonylpropionitrile respectively.
The Structure of the Capsular Polysaccharide of Klebsiella K-type 5
Authors: Dutton Guy G. S. , Yang Mo-Tai
Published: May 2006

Methylation, periodate oxidation and partial hydrolysis studies on the capsular polysaccharide, and on the carboxyl reduced polymer of Klebsiella K5 show the structure to consist of a repeating unit:[Formula: see text]The polysaccharide has a molecular weight (by gel filtration) of 9 × 105 and is the first Klebsiella capsule to be found lacking a carbohydrate side chain. The proportion of O-acetyl and pyruvate groups was determined by p.m.r. spectroscopy.
Aqueous Nonelectrolyte Solutions. Part XII. Enthalpies of Mixing of Water and Deuterium Oxide with Tetrahydrofuran
Authors: Glew David N. , Watts Harry
Published: May 2006

Calorimetric enthalpies of mixing have been measured over the whole composition range for the water–tetrahydrofuran and the deuterium oxide – tetrahydrofuran systems at 10.00 and 25.00 °C. The experimental S-shaped, enthalpy of mixing –composition curves are interpreted in terms of changes of the water hydrogen bonding in solution. At low tetrahydrofuran mole fractions the deuterium oxide systems are more exothermal and at high tetrahydrofuran mole fractions more endothermal than the corresponding water systems. A good correlation is found between the enthalpy of mixing and the water proton magnetic resonance chemical shift for solutions with greater than 0.55 mole fraction of tetrahydrofuran.
Acid Ionizations of Nitroalkanes in Aqueous Solution
Authors: Matsui Takeki , Hepler Loren G.
Published: May 2006

Calorimetric measurements have led to ΔH0 values for ionization of nitromethane, nitroethane, 1-nitropropane, and 2-nitropropane in aqueous solution at 298°K. Combinations of these enthalpies with free energies from equilibrium constants for ionization have led to ΔS0 values for the ionization reactions. It is noted that the trend toward decreasing pK with methyl substitution in nitroalkanes is unusual compared to phenols and carboxylic acids. Similarly, correlations of ΔS0 with ΔG0 and ΔH0 are different for nitroalkanes than for other acids.
Reactions of Phosphorus Pentachloride with Ethyl-, Vinyl-, and Ethynyl(trichloromethyl)carbinol and with 1,1,1-Trichloro-3-nonyn-2-ol
Authors: Reeve E. Wilkins , Steckel Thomas F.
Published: May 2006

Reactions of phosphorus pentachloride with ethyl(trichloromethyl)carbinol (2), (trichloromethyl)-vinylcarbinol (7), ethynyl(trichloromethyl)carbinol (11a), and 1,1,1-trichloro-3-nonyn-2-ol (11b) have been studied. Whereas the reaction of phenyl(trichloromethyl)carbinol with phosphorus pentachloride leads to a nearly quantitative replacement of the hydroxyl group by chlorine, the reactions of the aliphatic (trichloromethyl)carbinols are more complicated. Thus the reaction of 2 with phosphorus pentachloride gave 18% of the normal product, 1,1,1,2-tetrachlorobutane (3), 13% of 1,1,2-trichloro-1-butene (4) from a dehydrohalogenation, and a higher boiling phosphate ester – acid chloride mixture. The alkynylcarbinols (11) gave tetrachlorobutynes (12) as well as tetrachloroallenes (13) by allylic rearrangement. A crystalline phosphate ester of 11a was also isolated. Several examples are given of catalytic rearrangements in the vapor phase of 1,1,1-trichloro-2-alkenes to 1,1,3-trichloro-1-alkenes.
The Preparation of 1,1′-Carbonyl- and 1,1′-Sulfinyl-dipyrazoles and their Reactions with Carbonyl Compounds
Authors: The K. I. , Peterson L. K. , Kiehlmann E.
Published: May 2006

The compounds 1,1′-carbonylbis(3-methylpyrazole) (1), 1,1′-carbonylbis(3,5-dimethylpyrazole) (2), and 1,1′-sulfinyldipyrazole (3) have been prepared. They react with aldehydes and ketones in the presence of metal ion catalysts to form 1,1′-alkylidenedipyrazoles together with carbon dioxide, from 1 and 2, or sulfur dioxide, from 3. Tetrapyrazol-1-ylmethane results from the pyrolysis at 200° of 1,1′-carbonyldipyrazole in the presence of cobalt(II) chloride.
Determination of Excess Volumes of Cyclohexane + Benzene Mixtures with a Mechanical Oscillator Densimeter
Authors: Kiyohara Osamu , Benson G. C.
Published: May 2006

Two methods of calibrating an Anton Parr densimeter were investigated. Values of the excess volume of cyclohexane + benzene mixtures obtained from density measurements at 25 °C with this instrument agree well with results in the literature.
N-Methylamino Acids in Peptide Synthesis. IV. Racemization and Yields in Peptide-bond Formation
Authors: McDermott John R. , Benoiton N. Leo
Published: May 2006

The racemization of an N-methylamino-acid residue during peptide-bond formation and mixed-anhydride activation has been investigated using Ala-MeLeu-Gly and Ala-MeLeu as model peptides. The results were compared with those for Ala-Leu-Gly, Ala-Leu, and Ala-Pro. The extents of racemization were determined by analysis of the diastereomeric products of the reactions after deprotection, using an amino-acid analyzer. Extensive racemization was detected after the hydrolysis of the mixed anhydrides of Bz-MeLeu, Z-Ala-MeLeu, and Z-Ala-Leu, but not of Boc-Ala-Pro and Z-MeIle. Significant racemization (2.8–39%) was observed when Z-Ala-MeLeu was coupled with Gly-OBzl by various methods in the presence of salts such as triethylamine hydrochloride or p-toluenesulfonate. Only coupling through the N-hydroxysuccinimide (HONSu) ester gave stereochemically pure product. In the absence of salt, less racemization was observed, but only couplings using N-ethoxycarbonyl-2-ethoxy-1,2-dihydroquinoline and N,N′-dicyclohexylcarbodiimide–HONSu gave essentially pure products. Polar solvents promoted racemization, but excess base did not. Chemical evidence that the racemization intermediate is an oxazolium-5-oxide has been obtained by trapping the intermediate as an addition product (a pyrrole) in 85% yield.The yields obtained by various coupling methods have been determined for several model peptides. Couplings at the carboxyl group of an N-methylamino acid gave high yields only in the absence of salt, except for coupling by the HONSu ester method. Couplings to an N-methylamino group gave high yields, except for coupling by the p-nitrophenyl ester method. Couplings to Ala-MeLeu-OBu′ gave higher yields than couplings to Ala-MeLeu-OBzl, presumably due to piperazine-dione formation by the latter.
Steric Effects in the Baeyer–Villiger Reaction of Simple Ketones
Authors: Winnik Mitchell A. , Stoute Valerie
Published: May 2006

The reactions of simple alkyl ketones with peroxytrifluoroacetic acid (PTFA) and peroxymaleic acid (PMA) have been examined. Magnitudes of steric effects in the Baeyer–Villiger reaction have been determined, the largest being a factor of 13 in neopentyl to ethyl migration in 5,5-dimethyl-3-hexanone. PMA is consistently more selective toward electronic differences in migrating groups. PTFA shows the greater sensitivity to steric effects.
Some Cobalt(II) Complexes in Non-aqueous Systems
Authors: Johnson K. E. , Meyer J. L.
Published: May 2006

By following the variation of absorptivity and energy of the principal electronic transitions with addition of ligand it is shown that CoCl2 gives rise to CoCl42− in γ-butyrolactone and Co(NO3)2 gives rise to dodecahedral Co(NO3)42− in γ-butyrolactone, propylene carbonate, and acetone.
Conformational Studies of 1,2-Disubstituted Indan Derivatives by Nuclear Magnetic Resonance Spectroscopy
Authors: Hall L. D. , Jones D. L.
Published: May 2006

The n.m.r. spectra of trans-2-bromo-1-fluoro-indan (2) have been analyzed, and the n.m.r. data used as the basis for a conformational assignment.
Organic Sulfur Mechanisms. 13. Sulfene Formation by a Reverse Diels–Alder Reaction
Authors: King James Frederick , Lewars Errol George
Published: May 2006

Dimethyl 2,2-dioxido-4-phenyl-2-thiabicyclo[2.2.2]octa-5,7-diene-5,6-dicarboxylate (5), a molecule purposely designed to undergo a thermal reverse Diels–Alder reaction to form sulfene and an aromatic co-fragment, has been synthesized. Thermolysis of 5 gave dimethyl biphenyl-2,3-dicarboxylate (7) and, in addition, (a) in the presence of an enamine (6) gave the appropriate sulfene–enamine adduct (8), and (b) with an excess of p-toluidine gave methanesulfon-p-toluidide (10), in agreement with the above expectation. In the absence of sulfene traps the only product identified, in addition to 7, was sulphur dioxide; further experiments failed to determine the fate of the methylene group but serve to exclude certain possibilities, including fragmentation of sulfene to sulphur dioxide and a trappable carbenoid species.
Gas Phase Solvation of the Ammonium Ion by NH3 and H2O and Stabilities of Mixed Clusters NH4+ (NH3)n(H2O)w
Authors: Payzant J. D. , Cunningham A. J. , Kebarle P.
Published: May 2006

The gas phase equilibria[Formula: see text]and those leading to mixed clusters like[Formula: see text]were measured with a pulsed electron beam high pressure ion source mass spectrometer. The ion source contained pure ammonia or mixtures of ammonia and water vapor at pressures in the Torr range. Determination of the temperature dependence of the equilibrium constants led to the evaluation of ΔG0, ΔH0, and ΔS0 values for the equilibria from n = 1 to 4 and w = 1 to 5. The ΔG0 values for the NH4+(NH3)n equilibria were in good agreement with previous determinations from this laboratory. Fair agreement was observed for the ΔH0 and ΔS0 values. Comparison with the corresponding results for NH4+(H2O)w showed that the ΔHn,n−1 and ΔG0n,n−1 were larger than ΔHw,w−1 and ΔG0w,w−1. The difference was largest for the first step (1,0) and decreased progressively until a reversal with water values becoming larger occurred at the (5,4) step. The stronger hydrogen bonds of NH3 to NH4+ for low ligand numbers is explained by the greater basicity of NH3. As the ionic charge becomes dispersed and more distant stronger interactions are obtained with water which gives stronger H bonds in the absence of positive ionic charge. Breaks in the ΔHn,n−1 values indicate existence of a relatively stable NH4+(NH3)4 symmetric ion. A much smaller and less distinct break is observed with pure water ligands.The mixed ammonia–water clusters show similar effects. The addition of a NH3 molecule to a pure water ligand complex gives the strongest interaction. The addition of H2O to a pure ammonia cluster gives the weakest interaction. The above effect is strongest at lowest ligand numbers. The difference decreases gradually and becomes reversed for more than four ligands.
Metabolites from a Scytalidium Species
Authors: Findlay John A. , Kwan David
Published: May 2006

The structure 1, 3,6,8-trihydroxytetralone, proposed (1) earlier for scytalone is corroborated by synthesis of an aromatization product 1,3,8-trimethoxynaphthalene. A new minor metabolite of the same Scytalidium species is shown to be 4,8-dihydroxytetralone (6).
The Effect of Refractive Index of the Medium on the Position of the Camera Lens in Schlieren Optics
Authors: Epstein L. Ivan , Nixon Percival , Richard Alfred J.
Published: May 2006

A linear relation has been established between the plane of focus for schlieren optics in the ultracentrifuge cell along the optic axis, and the refractive index of the liquid contained in the cell. Such a relation shows that there occurs a defocussing effect when a large change in refractive index is generated in the liquid column during centrifugation of multi-component systems.
γ-Deuterium Isotope Effects on Solvolysis of 7-Halonorbornyl Brosylates-6-d
Authors: Werstiuk Nick H. , Timmins George , Cappelli Frank P.
Published: May 2006

The γ-deuterium isotope effects for the solvolysis of anti- and syn-7-chloro-, anti- and.syn-7-bromo-exo-2-norbornyl brosylates-6-endo-d and.syn-7-chloro-exo-2-norbornyl brosylate-5,6-exo,exo-d2 in 80:20 EtOH–H2O, 0.04 M NaOAc at 65° are 1.11 ± 0.01, 1.11 ± 0.01, 1.13 ± 0.01, 1.05 ± 0.01, and 1.11 ± 0.01, respectively. The results indicate that the γ-isotope effect observed in the solvolysis of exo-norbornyl brosylate likely is not derived via neighboring group (non-vertical) participation of the C1—C6 bond.
Diffusion of Light Hydrocarbons in 5A Zeolite
Authors: Ruthven D. M. , Derrah R. I. , Loughlin K. F.
Published: May 2006

Experimental diffusivity data are presented for the diffusion of ethane, ethylene, propane, propylene, cyclopropane, n-butane, 1-butene, cis-2-butene, and trans-2-butene in Linde 5A zeolite. It is shown that the concentration dependence of the diffusivity may be accounted for by considering the non-linearity of the equilibrium isotherms. Activation energies for diffusion, derived from the temperature dependence of the limiting diffusivity at zero sorbate concentration, show a clear correlation with the critical diameters of the sorbate molecules. The data are interpreted in terms of the transition state theory of diffusion and it is shown that, for the simpler molecules, this theory gives a quantitatively correct prediction of the pre-exponential factor governing the temperature dependence of the zeolitic diffusivity.
A Kinetic and Surface Study of the Water-Gas Shift Reaction on Manganese(II) Oxide
Authors: Krupay Bordan Walter , Ross Robert Anderson
Published: May 2006

The kinetics of the water-gas shift reaction on a manganese(II) oxide catalyst possessing surface nonstoichiometry has been studied from 300 to 400 °C at atmospheric pressure. The experimental rate expression obtained was r = k(pCO)0.75 in the carbon monoxide partial pressure range 20 to 80 Torr and r = k(pCO)0.5 from 100 to 240 Torr. The rate of reaction has been related to the Langmuirian-type adsorption of carbon monoxide and a redox mechanism involving surface oxygen species is proposed. When the reaction rate was determined in increasing 10 °C intervals from 300 °C, two activation energies were observed; 16 ± 0.5 kcal mol−1 from 350 to 400 °C and 11 ± 0.5 kcal mol−1 from 300 to 340 °C. The temperature at which the change occurs corresponds closely to the Curie temperature of the oxide. The possible use of manganese(II) oxide as a catalyst or catalyst component in a commercial shift process is critically appraised.La cinétique de la réaction de déplacement eau-gaz sur un catalyseur oxyde de manganèse(II) ayant une surface non stoechiométrique a été étudiée de 300 à 400 °C à la pression atmosphérique. L'expression de vitesse expérimentale obtenue était r = k(pCO)0.75 dans l'intervalle de pression partielle en monoxyde de carbone de 20 à 80 Torr et r = k(pCO)0.5 de 100 à 240 Torr. La vitesse de réaction a été reliée à l'adsorption du type Langmuir du monoxyde de carbone et un mécanisme rédox faisant intervenir une espèce oxygène à la surface a été proposé. Lorsque la vitesse de réaction a été déterminée en augmentant la température par des écarts de 10 °C à partir de 300 °C, deux énergies d'activation ont été observées; 16 ± 0.5 kcal mol−1 de 350 à 400 °C et 11 ± 0.5 kcal mol−1 de 300 à 340 °C. La température à laquelle le changement se produit correspond étroitement à la température de Curie de l'oxyde.
Solubility Products of Aluminum Hydroxide in Various Ionic Solutions
Authors: Chen David T. Y.
Published: May 2006

Solubility products of Al(OH)3 were determined in various solutions of NH4+, Li+, Na+, K+, and Ca2+ ions. Increasing amounts of these hydroxides were added to the respective chloride solutions containing aluminum chloride. The solutions were aged for 3 months. Activities of the OH− ions were calculated from the pH values of the solutions. The total Al concentrations remaining in solutions were determined by Hsu's modified aluminon method. The Al3+ ion concentrations were computed using the hydrolysis equilibria of Aveston. The ion product, aAl3+(aOH−)3, was found to vary linearly with the [OH]/[Al] ratio. The solubility product of Al(OH)3 was obtained by extrapolating this ratio to 3. The pKsp values thus obtained were 30.55, 33.15, 30.75, 30.36, and 31.00 in NH4+, Li+, Na+, K+, and Ca2+ systems respectively. The anomalously low solubility product of Al(OH)3 in the Li+ system was attributed to the specific "lithium effect".
Reactivity of the Thallium(I) Salts of 3-Hydroxy-1,3,5(10)-estratrien-17-one and 1,3,5(10)-Estratriene-3,17β-diol. Preparation of 17-Oxoestra-1,3,5(10)-trien-3-yl 2′-Acetamido-3′,4′,6′-tri-O-acebtyl-2′-deoxy-β-D-glucopyranoside
Authors: Paquet Alenka , Layne Donald S.
Published: May 2006

Thallium(I) salts of estrone and 17β-estradiol were prepared in high yields by the reaction of estrone or 17β-estradiol with thallium(I) ethoxide. Both compounds were found to be reactive intermediates for alkylation and acylation of the steroid. The preparation and characterization of 17-oxoestra-1,3,5(10)-trien-3-yl 2′-acetamido-2′-deoxy-β-D-glucopyranoside by reaction of the thallium(I) salt of estrone with 2-trifluoroacetamido-3,4,6-tri-O-acetyl-2-deoxy-β-D-glucopyranosyl bromide is described.
Internal Substitution of 5α-Lanostane on C-5, C-6, and C-8
Authors: Edwards O. E. , Paryzek Z.
Published: May 2006

Thermolysis of 3β-acetoxy-11-oxolanostan-7α-yl azidoformate gave the cyclic carbamate of 3β-acetoxy-5α-amino-11-oxolanostan-7β-ol (9%) and the corresponding 6α-amino (52%) derivative. 3β-Acetoxy-11-oxolanostan-7β-yl azidoformate gave the cyclic carbamate of 3β-acetoxy-6α-amino-11-oxolanostan-7β-ol (52%) and the corresponding 6β-amino (26%) and 8β-amino (7%) derivatives. Some features of the l3C.m.r. and c.d. spectra of the above compounds and related steroids are described.
Unusual Reactivity Differences in the Decalone Series
Authors: Schmidt Cirill
Published: May 2006

It was found that an 8α-axial substituent in a 2α,5α,9β-trimethyl-1,4-decaldione system exercises an extraordinary steric hindrance in the reduction of the 1-keto group. Therefore the 4-keto group was reduced in the three compounds 7b, 13, and 22 with complete selectivity. In the absence of such a substituent the 1-keto group is reduced in preference to the 4-keto group (1, 5) with almost complete selectivity. An interplay of 1,3-diaxial and 1,3-peri-diequatorial interactions is involved to explain the unusual stereochemical behavior in these compounds. The blocking effect of the 8α-axial group was found to be independent of its own polarity. The steric preference of the reductions does not seem to be influenced by variously located double bonds in the decaline system.
Dielectric Loss of Adsorbed Polar Molecules
Authors: McMullen T.
Published: May 2006

A theory of the dielectric susceptibility of polar gases adsorbed on ionic solids is presented. The rotational oscillator model of an adsorbed polar molecule is used, and dielectric loss is assumed to occur by phonon emission and absorption. For linear coupling of the rotational oscillator to the lattice vibrations, an exact solution is found using diagrammatic perturbation theory at finite temperature. In this model, appreciable loss is only found if the density of phonon states near the classical oscillator frequency is reasonably large, and it is suggested that this is to be expected in situations where the rotational oscillator model is valid. The method can be extended to more complex adsorbate–lattice interactions.
Influence of Lewis Acids on the Diels–Alder Reaction. V. The Reaction of Furan with Dimethyl Acetylenedicarboxylate
Authors: McCulloch A.W. , Smith D. G. , McInnes A. G.
Published: May 2006

The Diels–Alder addition of furan to dimethyl acetylenedicarboxylate (DMAD) affords a monoadduct 1. The position and steric course of further addition of furan to the latter are temperature dependent. At temperatures of 50° or below addition occurs mainly at the activated double bond to give endo-endo4 and endo-exo5 diadducts. At 100° addition occurs at the less substituted double bond of the monoadduct to give analogous endo-endo7 and endo-exo9 diadducts; further addition of furan to the latter at 100° affords four triadducts 12–15. The configurations of all these products were determined by p.m.r. and assignments confirmed by simulation of the spectra.AlCl3 causes enormous rate enhancement of the Diels–Alder additions of furan to DMAD and to the activated double bond of the monoadduct. In the presence of the Lewis acid the predominant diadduct formed is the endo-exo isomer 5.
Structure of the Second Coordination Sphere of Transition Metal Complexes. IV. Solvent Effects
Authors: Eaton D. R. , Chua K. L.
Published: May 2006

The participation of various solvents in the second coordination sphere of Co(II) pyrazolylborate has been investigated. Equilibrium constants relative to carbon tetrachloride as a second sphere ligand have been obtained. The ability of a solvent to participate in the second sphere depends predominantly on its dipole moment and it is concluded that Van der Waals forces are responsible for outer sphere binding.
Kinetic Studies of the Reaction of Picryl Chloride with Sodium Methoxide in Methanol
Authors: Gan Leong Huat , Norris Albert Richard
Published: May 2006

Picryl chloride reacts rapidly with methoxide ion in methanol to form a σ-complex containing methoxide ion attached to the C-3 position of the picryl chloride. Thermodynamic and kinetic parameters characterizing this reaction are presented and compared with corresponding parameters for the analogous reaction of methoxide ion and 2,4,6-trinitroanisole in methanol. Details concerning the much slower formation of the σ-complex containing methoxide ion added to the C-1 position of picryl chloride are also presented.
Kinetic and Thermodynamic Studies of the Reactions of Sulfite Ion with Picramide, N-Methylpicramide, and N,N-Dimethylpicramide in Aqueous Solution
Authors: Buncel Erwin , Norris Albert Richard , Russell Kenneth Edwin , Sheridan Peter Jura
Published: May 2006

The kinetics of the reactions between sulfite ion and picramide, N-methylpicramide, and N,N-dimethylpicramide, to form 1:1 σ-complexes in aqueous solutions of constant ionic strength 0.14 M, have been investigated using a stopped-flow spectrophotometer. Specific rate constants for the formation and decomposition of these three complexes at 25.0 °C are 5.7 ± 0.2 × 104M−1 s−1 and 7 ± 1 s−1, 1.4 ± 0.1 × 104M−1 s−1 and 0.20 ± 0.02 s−1, and 4.1 ± 0.2 × 103M−1 s−1 and 0.14 ± 0.04 s−1, respectively. Enthalpies and entropies of activation characterizing the formation of the 1:1 σ-complexes have been determined. Equilibrium constants, determined spectrophotometrically at a number of temperatures, have been used to calculate the enthalpy (ΔH0) and entropy (ΔS0) changes associated with 1:1 and 2:1 σ-complex formation. These values are compared with corresponding ones for complex formation of sulfite ion with 1,3,5-trinitrobenzene and 2,4,6-trinitrobenzaldehyde. The extent of solvation of the σ-complexes is considered to play a primary role in determining the observed trends in the enthalpies and entropies of reaction.
A Reconsideration of the Validity of Correlating Substituent-induced Proton Chemical Shifts in Aromatic Derivatives with Reactivity Parameters
Authors: Dawson Daniel A. , Hamer Gordon K. , Reynolds William F.
Published: May 2006

Comparisons of 1H chemical shifts and charge densities (determined by CNDO/2 MO calculations) for 4-substituted derivatives of styrene, toluene, benzylchloride, and N,N,N-trimethylphenylammonium ion indicate that the chemical shifts primarily reflect intramolecular electronic effects. These effects are reflected by correlations of 1H chemical shifts with the F and R reactivity parameters of Swain and Lupton. It is concluded that it is valid to correlate substituent-induced chemical shifts for aromatic derivatives with divided reactivity parameters provided that (1) chemical shifts are measured at infinite dilution in a non-polar medium and (2) at least ten derivatives of each family are investigated.Calculations for 4-substituted toluenes indicate that there will be a small conformational dependence for substituent-induced benzylic proton chemical shifts.
The 2980 Å Absorption Spectrum of 1,2,5-Selenadiazole
Authors: Richardson A. W.
Published: May 2006

The u.v. absorption spectrum of 1,2,5-selenadiazole in the 3050–2600 Å region has been recorded and, by analogy to previous studies of furazan (1,2,5-oxadiazole) and 1,2,5-thiadiazole, an interpretation of the spectrum in terms of an allowed electronic transition involving primarily activity of ν5, a symmetric ring in-plane bending vibration, and ν10, a ring out-of-plane bending vibration, has been made. This analysis indicates that the excited state is non-planar, and the barrier to planarity has been calculated to be in the order of 115 cm−1.
A New Synthesis of 4-(4-Methyl-4-hydroxyamyl)-Δ3-cyclohexenecarboxaldehyde
Authors: Kogami Kunio , Takahashi Osamu , Kumanotani Ju
Published: May 2006

A new synthetic route of 4-(4-methyl-4-hydroxyamyl)-Δ3-cyclohexenecarboxaldehyde (Lyral) from myrcene (1) was investigated. It involves subjecting 1 first to the diene synthesis with acrolein (2) followed by hydration of the morpholine enamine of the adduct in 50% sulfuric acid at 0–5° and the subsequent hydrolysis in diluted sulfuric acid at 15–20°.The present method is superior in simplicity as well as productivity for the preparation of Lyral to any other methods hitherto reported.
Photochemistry of Glycosyl Azides
Authors: Plenkiewicz Jan , Hay George W. , Szarek Walter A.
Published: May 2006

Irradiation with u.v. light of a methanolic solution of β-D-glucopyranosyl (1), α-D-mannopyranosyl (3), or β-D-galactopyranosyl (4) azide affords in good yield the corresponding next-lower aldose. In the case of β-maltosyl (6), β-D-ribofuranosyl (7), or α-L-arabinopyranosyl (8) azide, there was observed the formation of an intermediate which, on standing in the dark, reverts back to starting material.
Molecular Rearrangements. Part IV. Aryl (Alkyl) Amines (1), Thermal Rearrangement of N-Benzyl-N-Methylaniline
Authors: Badr M. Zarif A. , Aly M. M.
Published: May 2006

Heating N-benzyl-N-methylaniline under reflux or heating at ∼315° in sealed tubes, in the absence of any promotor for 100 h, resulted in its rearrangement, producing methylamine, diphenylmethane, and dibenzyl together with o-toluidine and 4-methylacridine. Heating N-methylaniline in a sealed tube under the same conditions, in absence of any promotor, resulted in its rearrangement, producing methylamine and o-toluidine together with unidentified neutral products.When pyrolysis of the tertiary amine was carried out with quinoline as a solvent, the normal products of rearrangement were obtained together with 2-and 4-benzylquinolines and 2,2′-biquinolyl.The reaction mechanism is discussed on the basis of the products separated, from which it is concluded that the tertiary amine undergoes homolytic fission to benzyl and N-methylphenylamino free radicals, followed by a series of homolytic fissions of initially separated intermediate products, during the rearrangement process. Throughout the whole mechanism, the C—N bonds are the only ones to suffer homolytic fission.
Catalytic Activation of Molecular Hydrogen by Ruthenium Chloride Complexes in N,N-Dimethylacetamide Solution
Authors: Hui Benjamin C. , James Brian R.
Published: May 2006

N, N-Dimethylacetamide solutions of "RuCl3•3H2O", which is a mixture of Ru (IV) and Ru(III), react with hydrogen under mild conditions in stepwise stoichiometric processes to give finally univalent species [Formula: see text]. Reactions 1 and 2 involve heterolytic activation of H2 by a Ru III catalyst and likely proceed via a RuIIIH intermediate; the same catalyst catalyzes the hydrogenolysis of oxygen to water. Reaction 3 involves a RuIIH intermediate. Kinetic parameters are presented for processes 1–3 and the catalytic water production, and are compared with data for some systems that have been studied previously in aqueous acid chloride solutions. Reactions 1 and 2 occur much more readily in the non-aqueous solvent due to a lower activation energy, while reaction 3 occurs only in the non-aqueous system. A detailed interpretation of the data is limited by the uncertain nature of species present in the amide solvent.
Molecular Association of Hydrogen Bonding Solutes, o-, m-, and p-Cresol, in Carbon Tetrachloride
Authors: Woolley Earl M. , Rushforth Dennis S.
Published: May 2006

The intermolecular hydrogen-bonding self-association of the three cresols in CCl4 solutions at 25 °C has been investigated by calorimetric means. Calorimetrically determined heats of dilution of each of the cresols in anhydrous CCl4 are interpreted in terms of two different models: (i) dimerization and trimerization self-association reactions, and (ii) dimerization followed by stepwise polymerization self-association reactions. Values of K, ΔH0, and ΔS0 for these reactions are calculated using least-squares and other methods. Results show that o-cresol is clearly less associated in anhydrous CCl4 solution at 25 °C than either m- or p-cresol. Values of K2 and K3 (both based on molar concentrations of solutes) and ΔH20and ΔH30 (kcal) for the reactions [Formula: see text] respectively, are o-cresol: 0.7, 1.3,−3.4,−12.5; m-cresol: 0.8, 5.0,−5.0,−13.6; p-cresol: 0.35, 6.5,−5.5,−13.4. Values of K2 and Ks (both based on molar concentrations of solutes) and ΔH20 and ΔHs0 (kcal) for the reactions [Formula: see text] (all n > 2 with same Ks and ΔHS0), respectively, are o-cresol: 0.7, 1.6, −4.2, −4.5; m-cresol: 1.2, 4.0, −5.0, −4.3; p-cresol: 1.0, 7.0, −3.3, −3.5.
The Trishomocyclopropenyl Cation. II. An Ethano-bridged Derivative
Authors: Masamune S. , Sakai M. , Kemp-Jones A. V.
Published: May 2006

An ethano-bridged trishomocyclopropenyl carbonium ion has been generated in superacid media from 8-chlorotricyclo[3.2.1.02,4]octane and/or 4-chlorotricyclo[3.3.0.02,8]octane. The 1H and 13C n.m.r. spectra of this new stable carbonium ion compare well with those of the parent trishomocyclopropenyl carbonium ion and yet show some indication that the degree of charge delocalization is more extensive than that originally implied.
Intrinsic Acidities of α, β, γ Chlorosubstituted Aliphatic Acids from Gas Phase Equilibrian Mesurements
Authors: Yamdagni R. , Kebarle P.
Published: May 2006

Measurements of the proton transfer equilibria: A1− + A2H = A2− with a pulsed electron beam high pressure mass spectrometer were extended to α, β, γ chlorosubstituted aliphatic acids. The equilibrium constants were used to evaluate ΔG0 for the proton transfer reactions. Assuming ΔG ≈ ΔH and using standard acids AH for which the difference between the bond dissociation energy D(A—H) and the electron affinity of A, EA(A) was known one could evaluate the corresponding difference for the newly measured acids and place them on an absolute acidity scale. The gas phase acidity was observed to increase in the order: acetic, propionic, butyric, γ-Cl butyric, β-Cl butyric, β-Cl propionic, α-Cl butyric, α-Cl propionic, α-Cl acetic. The gas phase acidities are compared with those observed in aqueous solution. The effects of the Cl substituent parallel those in solution but are much larger. The attenuation occurring in solution is attributed to weaker hydrogen bonding of the chloro stabilized acid anions to water molecules.
Reactivity of Organophosphates. IV. Acid-catalyzed Hydrolysis of Triethyl Phosphate: a Comparison with Ethyl Acetate
Authors: Lyznicki Jr. Edward P. , Oyama Kiyotaka , Tidwell Thomas T.
Published: May 2006

The hydrolysis of triethyl phosphate in water and in 35% dioxane – 65% water has been examined. Hydrolysis in neutral water proceeds with a rate constant of 8.35 × 10−6 s−1 at 101°, ΔH* = 23.4 kcal/mol, ΔS* = −20 e.u., a solvent isotope effect [Formula: see text] of 1.3, C—O bond cleavage as shown by 18O labeling, and no catalysis by 0.5 M sulfuric acid. These results are consistent with the BAL2 mechanism of hydrolysis and the same pathway is indicated for the reaction in neutral 35% dioxane –65% water. Perchloric acid catalyzes the reaction in dioxane–water with C—O bond cleavage in 0.904 M acid, ΔH* = 24.1 kcal/mol, ΔS* = −17 e.u., and the solvent isotope effect [Formula: see text] in 0.556 M acid. These results indicate that the AAL2 pathway of hydrolysis is followed under these conditions. The reactivity of triethyl phosphate is compared with that of ethyl acetate.
Energy Transfer Processes in the Stratosphere
Authors: Taylor Raymond L.
Published: May 2006

During the past decade or two considerable fundamental information has been acquired on the mechanisms and rates of molecular energy transfer among vibrational, rotational, and electronic states. It is a well-known fact that the rate and even the products of a chemical reaction can be markedly influenced by the degree of internal state excitation of the reactants. Also, it is clear that many of the chemical processes occurring in the upper atmosphere produce atoms or molecules in excited states. It will be the purpose of this paper to review the state of knowledge of energy transfer mechanisms and kinetic rates as it pertains to atmospheric constituents and to attempt to indicate possible important roles of energy transfer in the physics and chemistry of the stratosphere. Some specific examples will include vibrational relaxation of OH and O3, the possible role of atomic species as quenchants, and electronic/vibrational energy transfer processes.
Water-vapor Measurements in the Lower Stratosphere
Authors: Mastenbrook H. J.
Published: May 2006

Nearly 10 years of water-vapor measurements to heights of 30 km provide a basis for assessing the natural concentration of stratospheric water vapor and its variability. The measurements which began in 1964 have been made at monthly intervals from the mid-latitude location of Washington, D.C, using a balloon-borne frost-point hygrometer. The observations show the mixing ratio of water-vapor mass to air mass in the stratosphere to be in the general range of 1 to 4 p.p.m. with a modal concentration between 2 and 3 p.p.m. An annual cycle of mixing ratio is evident for the low stratosphere. A trend of water-vapor increase observed during the first 6 years does not persist beyond 1969 or 1970. The 6 year increase was followed by a marked decrease in 1971, with mixing ratios remaining generally below 3 p.p.m. thereafter. The measurements of recent years suggest that the series of observations may have begun during a period of low water-vapor concentration in the stratosphere.