bluuebunny/crossref_metadata_2025 huggingface dataset:
Oxidation of 1,4-Cyclohexadiene Dioxide with Dimethyl Sulfoxide
Authors: Mckague B.
Published: May 2006

The oxidation of 1,4-cyclohexadiene dioxide with dimethyl sulfoxide and boron trifluoride etherate catalysis yields catechol in 70–75% yield.
Molecular Conformation of 4-Thiouridine in Aqueous Solution
Authors: Hruska F. E. , Ogilvie K. K. , Smith A. A. , Wayborn H.
Published: May 2006

β-4-Thiouridine is a component of several tRNA molecules. A recent X-ray study has shown that this pyrimidine nucleoside favors the syn conformation in the crystalline state. The 100 and 220 MHz p.m.r. data and a comparison with those of uridine are presented here. A long-range five-bond spin–spin coupling interaction between the H-5 and -1′ hydrogens is noted. The results are consistent with an anti conformation for 4-thiouridine in an aqueous solution.
The Hydrocarbon-induced Fluorescence of Atoms in Flames
Authors: Blades A. T.
Published: May 2006

The phenomenon of chemiluminescent emission from atoms introduced into hydrocarbon flames has been studied in a basic hydrogen-oxygen diffusion flame at low hydrocarbon concentrations. Emissions from several atoms are first order in methane concentration and examination of the relative populations of the excited states of arsenic suggests a single excitation mechanism with available energy in excess of 8.5 eV. Previously proposed mechanisms are discussed and the available evidence favors the process[Formula: see text]as the origin of the energy of excitation.
Vibrational Spectra of 1,1-Dichlorocyclopropane
Authors: Freeman J. M. , Robinson P. J.
Published: May 2006

Infrared and Raman spectra of 1,1-dichlorocyclopropane are reported. Force constants were determined by an iterative computer procedure for two possible sets of assignments of the normal mode frequencies. It is suggested that in the correct assignment the methylene rocking modes are at higher frequency than the twisting modes.
The Kinetics and Mechanism of the Chloride–Chlorate Reaction in Moderately Concentrated Solutions of HClO4 and H2SO4 at 25 °C
Authors: Crisci P. , Lenzi F.
Published: May 2006

The stoichiometry and kinetics of the reaction[Formula: see text]have been determined at 25 °C in 3.0 – 5.8 M HClO4 and compare well with the results obtained in aqueous H2SO4. A mechanism involving a semi-ideal treatment of the dehydration equilibrium[Formula: see text]is consistent with the kinetic data in both media.
Kinetic Isotope Effects in the Radiation-induced Oxidation of Alcohols by Hydrogen Peroxide in Aqueous Solution
Authors: Burchill C. E. , Thompson G. F.
Published: May 2006

not available
Studies on Metal Hydroxy Compounds. XIII. Thermal Analyses and Decomposition Kinetics of Hydroxystannates of Bivalent Metals
Authors: Ramamurthy P. , Secco E. A.
Published: May 2006

The thermal analyses of hexahydroxystannates of bivalent metals of the type Me[Sn(OH)6], where Me = Zn, Co, Cu, Ni, Mn, Ca, Mg, Cd, Sr, reveal that the primary mode of decomposition occurs by dehydroxylation and subsequent decomposition of the metastannate residue occurs in the Zn, Cu, Mn, Ca, and Mg compounds. Calorimetric measurements along with related enthalpic values for the decomposition reaction are given. The kinetics of thermal decomposition of all compounds studied, except the Cd and Mg analogues, follow first order reaction kinetics up to α ~ 0.9.
Base-induced Rearrangement of γ-Diketones. I. The Rearrangement of 1,2,2-Triphenyl-1,4-pentanedione to 1,3,3-Triphenyl-1,4-pentanedione
Authors: Yates Peter , Abrams G. D. , Betts Michael J. , Goldstein S.
Published: May 2006

Treatment of 4-hydroxy-2,2-diphenyl-3-pentenoic acid lactone (3) with phenyllithium gives 1,2,2-triphenyl-1,4-pentanedione (2), 1,3,3-triphenyl-1,4-pentanedione (7), and 3,3-diphenylpropiophenone (16). The γ-diketone 7 is shown to arise via rearrangement of an anion of the γ-diketone 2. The formation of 1,2,3-triphenyl-1,4-pentanedione (27) is not observed, nor is 27 converted to 7 on treatment with base. It is concluded that the rearrangement proceeds via two homoenolate anion intermediates rather than via two 1,2 phenyl shifts.
Couplings into Methylene Groups: a New Nuclear Magnetic Resonance Approach to Stereochemistry
Authors: Slessor K. N. , Tracey A. S.
Published: May 2006

A method of assigning dihedral angles to hydrogens adjacent to a methylene function by using computer analyzed n.m.r. coupling constants in a modified Karplus equation is presented. The "Dihedral Angle Estimation by the Ratio Method" (DAERM) is based on the assumption that, although the magnitudes of the Karplus constants, k1 and k2, vary, the ratio of k1 to k2 is a constant. Dihedral angles computed in this way seem not to be influenced by the effects of ring strain and substituent electronegativity. The conformational preferences of several four- to six-membered ring Systems, some containing oxygen and sulfur atoms, have been investigated by this method. Molecular features such as ring puckering and flattening are indicated by DAERM as are some subtle electrostatic influences.
The Norrish Type II Photodecomposition of Di-n-Butyl Terephthalate
Authors: Day M. , Wiles D. M.
Published: May 2006

The liquid phase photolysis of undiluted di-n-butyl terephthalate yields 1-butene and carboxylic acid end groups as a result of a Norrish Type II photochemical rearrangement reaction. Quantum yields for the production of these two products have been determined and found to be [Formula: see text] and [Formula: see text] in vacuum and [Formula: see text] and [Formula: see text] in air.
Synthesis and Novel Rearrangement of 1,1,1-Trichloro-2-alken-4-ones
Authors: Kiehlmann Eberhard , Loo Pui-Wah , Menon B. C. , McGillivray Nora
Published: May 2006

Strong mineral acids convert 1,1,1-trichloro-2-hydroxy-4-alkanones to 1,1,1-trichloro-2-aIken-4-ones and 1,1,5-trichloro-1-alken-4-ones via an intramolecular chlorine shift from C-1 to −5 of an enol allylic system. Alternatively, 1,1,1-trichloro-2-alken-4-ones may be synthesized from 1,1,1-trichloro-2-hydroxy-4-alkanones by acetylation and elimination of acetic acid or by nucleophilic substitution with thionyl chloride followed by dehydrohalogenation. The two diastereomeric 1,1,1-trichloro-2-hydroxy-3-methyl-4-hexanones do not epimerize during acetylation, and the erythro-acetate resists elimination of acetic acid. Pyrolysis of 2-(1-hydroxy-2,2,2-trichloroethyl-)cyclohexanone yields 2-(2,2-dichlorovinyl)-2-cyclohexenone while treatment of 1,1,1,7,7,7-hexachloro-2,6-dihydroxy-4-heptanone with strong acid leads to the formation of 1,1,1,7,7,7-hexachloro-2,5-heptadien-4-one.
The Structure of Fumarofine
Authors: Yu C. K. , Saunders J. K. , MacLean D. B. , Manske R. H. F.
Published: May 2006

A structure is proposed for fumarofine (F-38), an alkaloid of Fumaria officinalis. It is shown by spectroscopic methods to be another representative of the spirobenzylisoquinoline group of alkaloids.
Proton Magnetic Resonance Spectra of Some Amphetamines and Related Compounds and Observations on Rotamer Populations
Authors: Bailey K. , By A. W. , Graham K. C. , Verner D.
Published: May 2006

Data from the p.m.r. spectra of β-amino-, β-aminohydrochloride-, β-hydroxy-, and β-nitro-α-phenyl-propanes having methyl or methoxy substituants on the phenyl ring (37 compounds in all) are presented. The α and β protons of the side-chain give a pattern usually analyzable as ABX. The data are discussed in terms of correlations of coupling constants and chemical shifts with electronegativity of the substituent groups, steric and electronic effects, and apparent changes in rotamer populations. Hydrogen-bonding between the amino group of amphetamines and a methoxyl function at the ortho position in the phenyl ring is indicated for the salts but not the free bases.
The Pressure Dependence of the Activation Volume
Authors: Gay D. L.
Published: May 2006

The analysis of the pressure dependence of the activation volume, (∂ΔV*/∂P)T, in terms of ion-dielectric theory has been performed. The values of (∂ΔV*/∂P)T obtained on this basis are in good agreement with those found for the hydrolyses of organic halides. These results further indicate that contributions to (∂ΔV*/∂P)T arising from compression of the molecule or ion are by far more important than those arising from electrostriction of the dielectric medium. Also, the effects of quadrupole moments can be very important since the contributions from this are as great as those from dipole moments. Nevertheless it seems that ion-dielectric theory gives only a partial answer to the question of the nature and origin of (∂ΔV*/∂P)T. Apparently, the contributions from solvent structure, un-accounted for on this model, cannot be ignored.
Infrared and Raman Spectra of Potassium and Sodium Borohydride
Authors: Harvey K. B. , McQuaker N. R.
Published: May 2006

Using both infrared and laser Raman techniques the low temperature vibrational spectra of KBH4, KBD4, NaBH4, and NaBD4 have been recorded. The spectra of the external lattice vibrations are consistent with the following borohydride ion site symmetries: Td for potassium borohydride and D2d for sodium borohydride. Translational frequencies are assigned and librational frequencies are inferred from absorptions tentatively assigned as second overtones. Comparison of the low and high temperature vibrational spectra suggests the following disorder–order phase changes: Oh5 → Td2 for potassium borohydride and Oh5 → D2d9 for sodium borohydride.
Isomers of 1-(4-Chlorophenyl)-2,3-dimethylisoindoline
Authors: Freter K. R. , Hess F. K. , Sygusch J. , Brisse F.
Published: May 2006

The chemical properties and n.m.r. data of the two isomers of 1-(4-chlorophenyl)-2,3-dimethyliso-indoline are reported. The crystal structure of one of the isomers was determined by X-ray diffraction.
Reactions of Some Fluorinated Acetylenes with Tetrakis(triphenylphosphine)platinum(0)
Authors: Cullen W. R. , Hou F. L.
Published: May 2006

The reactions of tetrakis(triphenylphosphine)platinum(0), (1) with 3,3,3-trifluoropropyne and 3,3,4,4,4-pentafluorobutyne produce cis-(P(C6H5)3)2Pt(C≡CCF3)2 and (P(C6H5)3)2Pt(C≡CC2F5)2, respectively. The analogous reaction between (1) and hexafluoro-2-butyne yields the known(P(C6H5)3)2Pt(F3CC2CF3).
The Penetrating Power of β-Decay Recoils of Epithermal Energies in Organic Matter
Authors: Shafrir N. H.
Published: May 2006

A method for the measurement of the extent of dislocation of the β-decaying nucleus from its equilibrium position is described. An ionized layer formed at the surface of an aqueous solution of an ionic surface-active substance served as a source of β-disintegrating atoms. The primary adsorbed surface-active ions give rise to an electrical double layer within the liquid phase. When the solution contains β-active ions, some will join the electrical double layer near the surface as counter ions. It was found that radioactive β-recoils arising in an adsorbed surface layer are able to leave the surface, collected on a negatively charged plate, and counted. In order to reach the gas phase, the β-recoils have to penetrate the primary organic adsorption layer. When the expanded adsorption layer is gradually compressed, particles of lower energy are stopped, resulting in decreased recoil activity. Extrapolation to zero β-recoil activity gives an approximate value for the mass per unit area of organic material which stops completely atoms of certain initial energy. For particle energies between 2 to 22 eV, a linear dependence is found between the maximum β-recoil energy and the "penetrating power". The corresponding organic stopping layers for this energy region are between 1.0 to about 1.6 × 10−7 g/cm2.
Ring–Chain Tautomerism of Hydroxyketones
Authors: Whiting Josephine E. , Edward J. T.
Published: May 2006

A study of the u.v., i.r., and n.m.r. spectra of 5-hydroxy-2-pentanone and of 6-hydroxy-2-hexanone has shown that in most organic solvents there is a slight preference for the open-chain form of the hydroxyketone over the cyclic hemiketal. Increase in temperature and in polarity of solvent further favors the open-chain tautomer; in water there was no evidence of any cyclic form.
Thermal Tautomerism of Crotonic Acid and Vinylacetic Acid, Neat and in Heavy Water
Authors: Hocking Martin B.
Published: May 2006

A distillate containing 25% vinylacetic acid has been obtained from trans-crotonic acid. Pure vinylacetic acid has been obtained from this by successive thermal equilibrations and distillations. Vinylacetic acid has been subjected to tautomerization conditions in acidic, neutral, and basic media, the latter in normal and in heavy water. These observations are coordinated in an attempt to arrive at plausible pathways for the various transformations observed.
The Reaction of Active Nitrogen with Carbonyl Chloride
Authors: Baker R. R. , Winkler C. A.
Published: May 2006

The reaction between active nitrogen and COCl2 in an unheated reaction vessel has been studied over a large range of initial reactant conditions. Analytical studies have shown CO and Cl2 to be the only reaction products, effectively produced in equal amounts. The maximum extent of reaction corresponded to no more than 10% of the available N atoms. The reaction was found to change from first order in both N and COCl2 for [COCl2]0/[N]0 < ~0.1, to zero order in COCl2 and second order in N, with [COCl2]0/[N]0 > ~0.3. The reaction appears to be initiated by energy transfer from an excited N2 species.
Studies of the Carbonatobis(R-propylenediamine)cobalt(III) Ion
Authors: Haines Roland A. , Smith Anthony A.
Published: May 2006

The complex carbonatobis(R-propylenediamine)cobalt(III) perchlorate, [Co(R-pn)2CO3]ClO4 has been prepared both as a mixture of isomers and as one pure optical isomer. The nature of the products is discussed and structures are assigned on the basis of c.d. and n.m.r. data.
Thiazoloisoquinolines. IV. The Synthesis and Spectra of Thiazolo[4,5-h]- and Thiazolo[5,4-f]isoquinolines. The Ultraviolet and Proton Magnetic Resonance Spectra of Some Substituted Isoquinolines
Authors: Taurins Alfred , Hsia Richard Kang-Chuan
Published: May 2006

Thiazolo[4,5-h]isoquinoline was synthesized from 7-aminoisoquinoline in four steps: by the reaction with potassium thiocyanate and bromine to give 7-amino-8-thiocyanoisoquinoline; cyclization of the latter with hydrochloric acid to produce 2-aminothiazolo[4,5-h]isoquinoline, followed by the Sandmeyer reaction to yield a 2-chloro derivative, and finally, reduction with hydriodic acid and phosphorus. Thiazolo[5,4-f]isoquinoline was prepared from 6-aminoisoquinoline via 6-amino-5-thiocyanoisoquinoline. The synthesis of 2,5-diaminothiazolo[5,4-h]isoquinoline was achieved by cyclization of 5-acetamido-8-aminoisoquinoline which was obtained from 5-aminoisoquinoline. In 5-amino-8-thiocyano- and 8-amino-5-thiocyanoisoquinolines, the thiocyano group was hydrolyzed to the thiol group with 8 N hydrochloric acid and ethanol (1:1).The u.v. and p.m.r. spectra of the intermediate isoquinolines, and the i.r., u.v., and n.m.r. spectra of thiazoloisoquinolines were studied.
A Study of the Barriers to Rotation in Some Highly Substituted Diphenyl Ethers
Authors: Bergman J. J. , Chandler W. D.
Published: May 2006

Energy barriers to rotation about Ar—O bonds have been obtained from an analysis of the variable temperature n.m.r. spectra of a number of highly substituted diphenyl ethers. These barriers are explained on the basis of structural and conformational effects and their implication for the resolution of optical isomers is discussed.
Synthesis and Isomerization of Adducts of Azodicarbonyl Compounds and Cyclopentadiene
Authors: Campbell J. A. , Mackay Donald , Sauer T. D.
Published: May 2006

The synthesis of a range of bicyclic Diels–Alder adducts (structures b) of cyclopentadiene with symmetrical and unsymmetrical azodicarbonyl compounds is described. Thermal isomerization of these adducts to the bicyclic 1,3,4-oxadiazines (structures c and d) is especially rapid with bulky acyl groups. In unsymmetrical adducts with acyl groups of markedly different size, the larger group dictates completely the direction of isomerization. Adducts with two different aroyl groups give both isomers.Spectroscopic properties of the adducts, the oxadiazines and the dihydro derivatives of the oxadiazines are described.
The Mechanism for Hydrolysis of Primary Alkyl Chlorosulfates in Water. The Kinetic Solvent Isotope Effect and the Secondary Deuterium Isotope Effect
Authors: Ko E. C. F. , Robertson R. E.
Published: May 2006

The temperature coefficients of the enthalpy of activation [Formula: see text] for the hydrolysis of the three chlorosulfates, methyl, ethyl, and β-chloro, are shown to have values of −50,−55, and −60 cal deg−1 mol−1; values in the same range as previously reported for the hydrolysis of the sulfonyl chlorides. The corresponding value for the β-methoxy isomer was −40 cal deg−1 mol−1, about the same as found for the p-methoxybenzenesulfonyl chloride. The kinetic solvent isotope effect, however, was significantly lower than reported for the sulfonyl chloride series, being about the same as found for the hydrolysis of the alkyl halides. While some degree of nucleophilic overlap is probably required in the activation process, the requirement here is reduced to about the same level as that for the primary halides, and there is no need to postulate a different mechanism on passing from the methyl to the ethyl member of the series, confirming the earlier conclusion of Buncel and Millington.
The Dissociation of Anilinium Ions in Aqueous Dimethylsulfoxide
Authors: Yates Keith , Welch Graeme
Published: May 2006

The pKa values often substituted primary anilines and six substituted tertiary anilines have been determined in 70% DMSO–water. The ΔpKa values relative to those in aqueous solution indicate that DMSO is about 2 log units stronger as a base than H2O. The normal order of basicity (tertiary > primary) is inverted in this solvent system and the Hammett ρ values for the two series provide evidence for a different ionization mechanism than that in water.
Reactions of Tetrasubstituted Azomethine Ylides Generated from Tetracyanoethylene Oxide
Authors: Lown J. W. , Matsumoto K.
Published: May 2006

Reaction of a series of Schiff bases (bearing substituents which effect electron release in either the benzal or aniline moieties), with tetracyanoethylene oxide generates several tetra-substituted azomethine ylides which may be trapped in the presence of dipolarophiles both heteromultiple and homomultiple. The methine n.m.r. assignments in the adducts are obtained by using benzal-[2H]1-2,4,6[2H]3-aniline in the reactions which results in > 98% deuterium incorporation. Diphenylcyclopropenone reacts preferentially with tetracyanoethylene oxide to give 3,4-diphenyl-5,5,6,6-tetracyano-5,6-dihydropyran-2-one while diphenylcyclopropenethione reacts with tetracyanoethylene oxide to give 1,2-diphenyl-3-dicyanomethylenecyclopropene in a 67% yield superior to that of existing preparations.
Influence of Surface Area Variation on the Kinetics of Hydration of Tricalcium Silicate
Authors: McCurdy K. G. , Erno B. P.
Published: May 2006

Tricalcium silicate reacts initially with aqueous solutions according to a rate law that is first order with respect to the mass of the solid. A kinetic investigation of the hydration of tricalcium silicate for fixed solid to solution, w/w, ratio has been conducted using samples of tricalcium silicate of different total surface area to volume ratios. Consideration of the pH independent rate constants indicates that the rate for the initial step in the hydration process is proportional to the surface area of the solid. Subsequent pH independent rate constants in the overall hydration process are surface area independent.
Stereochemistry of Dehydrogenation by D-Galactose Oxidase
Authors: Maradufu A. , Cree G. M. , Perlin A. S.
Published: May 2006

not available
Reactions of Thiyl Radicals. VII. Photolysis of Methyl Sulfide Vapor
Authors: Rao P. M. , Knight A. R.
Published: May 2006

The photolysis of methyl sulfide vapor has been investigated as a function of substrate pressure, exposure time, and temperature in the wavelength range 2000 to 2300 Å. The effects of added propane, sulfur hexafluoride, and 2-methylpentane have been studied. The principal products of the decomposition are CH4, C2H6, CH3SSCH3, and CH3SH. The data indicate direct C—S bond scission in the primary process giving rise to "hot" CH3 and CH3S radicals. A mechanism in which disproportionation of methylthiyl radicals is a very minor process is proposed.The reactions of CH3 and CH3S radicals with methyl sulfide have been examined also by photolyzing CH3SSCH3 and CH3COCH3 in the presence of CH3SCH3. Quantum yields at 2288 Å have been determined as a function of several variables. A number of rate parameters for the reactions of methyl radicals and methylthiyl radicals have been calculated.
Quaternary Nitrogen Heterocycles. I. Equilibrium and Spectral Data for Pseudobase Formation by the N-Methyl Cations of Diazanaphthalenes
Authors: Bunting John W. , Meathrel William G.
Published: May 2006

Equilibrium constants have been measured at 25° for the formation of pseudobases from the 2-methyl-phthalazinium, 1-methylquinoxalinium, 1-methyl- 1,5-naphthyridinium, 6-methyl-1,6-naphthyridinium, 7-methyl-1,7-naphthyridinium, 1-methyl-1,8-naphthyridinium, 1-methyl-3-nitroquinolinium, and 2-methyl-4-nitroisoquinolinium cations. Ionization constants have also been obtained for ionization of some of these pseudobases to alkoxide anions. For each cation the site of hydroxide attack has been determined by comparison of the u.v. and p.m.r. spectra of the pseudobases, the corresponding methoxide adducts, and the lithium aluminum hydride reduction products. In all cases, except for the 1-methylquinoxalinium cation, only one major pseudobase species is present in solution, and ring-opening does not occur to any appreciable extent. The pseudobase of the 1-methylquinoxalinium cation exists in equilibrium with a considerable amount of its covalent hydrate from addition of water across the C3—N4 bond.
Microwave Spectrum and Conformation of Tetrahydropyran
Authors: Rao V. M. , Kewley R.
Published: May 2006

not available
Separation of Gas Mixtures by Accommodation Pumping
Authors: Doetsch I. H. , Ryce S. A.
Published: May 2006

Enrichment of helium–argon gas mixtures by accommodation pumping in a 10-stage pump is described. With the warm half of the pump at room temperature, pumping ratios are reported for cold surfaces at 77, 195, and 273 °K.
The Stereochemistry of the Addition of Two Diazoalkanephosphonates to Norbornene and Norbornadiene; Photolysis of the Adducts. An Entry into the Dimethyl Tricyclo[2.1.1.02.4]octyl Phosphonate System
Authors: Callot Henry J. , Benezra Claude
Published: May 2006

Dimethyl phenyldiazomethyl- and methyldiazomethylphosphonates were treated with norbornene and norbornadiene and the configuration of the Δ1-pyrazolines obtained (3–8) was deduced from n.m.r. by using the dihedral angular dependence relationship of vicinal 31P,1H couplings. The adducts were photolyzed under sensitized and non-sensitized conditions. The resulting cyclopropyl derivatives (9–12 and 14–17) were assigned configuration by using n.m.r. data. The results are discussed in terms of steric and electronic factors. The n.m.r. and mass spectral data are also discussed.
Constantes de stabilité de cyano-complexes d'argent et produit de solubilité de AgCN
Authors: Gübeli A. O. , Côté P. A.
Published: May 2006

The slope method has been applied to the determination of the cumulative formation constants of [Formula: see text] and Ag(OH)CN− and to the measure of the solubility product of AgCN, in 1 M NaClO4, at 25 °C.
Studies on Metal Carboxylates. Part II. Cobalt(II) and Nickel(II) Complexes of Certain Pyridine Carboxylic Acids and Pyridine-3-Sulfonic Acid: Magnetic and Spectral Studies
Authors: Anagnostopoulos A. , Matthews R. W. , Walton R. A.
Published: May 2006

Several pyridine carboxylate complexes of cobalt(II) and nickel(II) have been prepared and their spectral and magnetic properties and X-ray powder patterns used to establish their stereochemistry. The cobalt(II) complex of pyridine-3-carboxylic acid Co[3-py(CO2)]2•4H2O, whose crystal structure we have previously reported, was used as a model for a consideration of the structural details of these complexes. Like the latter cobalt(II) derivative, the nickel(II) complex of pyridine-3-carboxylic acid and the cobalt(II) and nickel(II) complexes of pyridine-4-carboxylic acid and pyridine-3-sulfonic acid, isolated as their tetrahydrates, are formulated as non-classical zwitterions. Comparisons are made with the related pyridine carboxylate complexes of silver(II).
Desorption of Hydrogen from Palladium and Palladium-Silver Alloys followed by Differential Scanning Calorimetry
Authors: Artman D. , Flanagan Ted B.
Published: May 2006

Differential scanning calorimetric curves have been obtained corresponding to the desorption of hydrogen from palladium and palladium–silver alloys. There was no evidence for the existence of an exotherm, following the endothermic desorption of hydrogen, which has been previously found and attributed to the relaxation of a metastable, expanded hydrogen-free palladium lattice. Heats of desorption have been evaluated from the areas of the endotherms and these are reasonable in the light of values obtained by other techniques. Comparisons of scanning curves for palladized and unpalladized hydrogen-containing silver–palladium alloys demonstrate that solid-state diffusion cannot be the slow step for the former but may be for the latter.
Steroids and Steroidases. XIV. Studies on the Reactions of 2-Lithio-1,3-dithianes with Steroids Possessing Spiroepoxide Functions at C-32
Authors: Jones J. Bryan , Grayshan Roger
Published: May 2006

The scope of the reactions of lithio-dithianes with spiro-epoxides for various stereospecific functionalizations of alicyclic systems has been illustrated by their application to spiro-3α- and -3β-oxiranes of the 5α-cholestane and 5α-androstane series.
Steroids and Steroidases. XV. Investigations of Some 2-Lithio-1,3-dithiane Reactions Directed Towards the Introduction of Corticoid and Related Functions at C-17 of the Steroid Nucleus
Authors: Jones J. Bryan , Grayshan Roger
Published: May 2006

The potential of 2-lithio-1,3-dithiane reactions for the introduction of corticoid and related C-17 functions into the steroid nucleus has been explored. Although attempts to effect the direct addition of the dithiane reagents to C-17 ketones met with limited success, reactions of C-17 spiroepoxides were found to provide a convenient entry into routes to homocorticoid compounds.
The Preparation of 1,2-Dimethylarsinohexafluorocyclopentene, 1,2-Dimethylarsinooctafluorocyclohexene, and Related Mixed Ligands
Authors: Chia L. S. , Cullen W. R.
Published: May 2006

Dimethylarsine reacts with the compounds [Formula: see text] to give the ligands[Formula: see text]fnfars(n = 4, 6, 8) The reaction of diphenylphosphine with [Formula: see text] results in the mixed ligands[Formula: see text]fnAsP (n = 4, 6, 8)
Sulfonation and Isomerization of some Halogenobenzenesulfonic Acids
Authors: Cerfontain H. , Koeberg-Telder Mrs. A. , Voorspuy W. A. Zwart
Published: May 2006

The behavior of the isomeric halogenobenzenesulfonic acids (halogen = F, Cl, and Br) in sulfuric acid was studied. In 115% H2SO4 at 25° only sulfonation takes place. Both the ortho- and para-isomers yield the 1-halogenobenzene-2,4-disulfonic acid, whereas the meta-isomers yield a mixture of mainly 3,4- and 3,5- with some 2,5-disulfonic acid.In 98.1% H2SO4 at 150–170°, both sulfonation and isomerization occur. The ortho-isomers are sulfonated to the 2,4-disulfonic acid and isomerized to the para-isomer in competing reactions. The para-isomers are sulfonated to the 2,4-disulfonic acids much more slowly than the ortho-isomers. The least reactive are the meta-isomers which in competing reactions are sulfonated to a mixture of mainly 2,5- and 3,5- disulfonic acids, and isomerized to the para-isomers which eventually yield the 2,4-disulfonic acids.It is suggested that the formation of the 3,4-disulfonic acids from the meta-isomers in 115% H2SO4 proceeds by an intramolecular rearrangement of the initially formed arenepyrosulfonic acids.
Conductivity and Viscosity of the Tetrabutylammonium Bromide – Carbon Tetrachloride System
Authors: Denning K. F. , Plambeck James A.
Published: May 2006

Conductivity and viscosity measurements have been made on tetra-n-butylammonium bromide – carbon tetrachloride solutions for the mole ratio range 1:40 to 1:2 at temperatures from 25 to 40 °C. At any individual concentration, both conductivity and viscosity follow an Arrhenius type temperature dependence. Viscosity increases exponentially with tetrabutylammonium bromide concentration while conductivity has a maximum at approximately 1:5 mole ratio R4NBr–CCl4.
Proton Magnetic Resonance Spectrum of 1-Penten-3-yne. INDO and CNDO/2 Molecular Orbital Calculations on Long-Range Spin–Spin Coupling Constants in Enynes
Authors: Ernst L. , Hutton H. M. , Schaefer T.
Published: May 2006

The high resolution p.m.r. spectra of 1-penten-3-yne in carbon disulfide and in benzene solution are analyzed. Long-range spin–spin coupling constants are discussed in terms of σ and π electron contributions. Comparisons are made with the isomeric 2-methyl-1-buten-3-yne and the parent compound, vinylacetylene. The results of INDO and CNDO/2 molecular orbital calculations are compared to the experimental coupling constants. It is concluded that the π electron contribution to 5J in enyne systems is +0.6 to 0.7 Hz and that σ electron contributions are rather small, the transoid ("pseudo-zig–zag") being larger than the cisoid one. Observed allylic coupling constants in the propene derivative are compared with the calculated values, including those for propene and 2-cyanopropene, available in the literature.
The Synthesis of Two Phenacetin Metabolites
Authors: Focella A. , Heslin P. , Teitel S.
Published: May 2006

A new metabolite of phenacetin was identified as 4-hydroxy-3-methylthioacetanilide (11). The synthesis of 11 and the isomeric 4-hydroxy-2-methylthioacetanilide (4) as well as that of the previously reported phenacetin metabolite 3-[(5-acetamido-2-hydroxyphenyl)thio]alanine (18) is described.
The Ultraviolet Absorption Spectrum of Furazan
Authors: Forrest B. J. , Richardson A. W.
Published: May 2006

The ultraviolet absorption spectrum of furazan (1,2,5-oxadiazole) in the region 2500–2300 Å has been recorded and analyzed as a π→π* transition from the planar ground state to a non-planar excited state having a potential barrier to planarity of about 215 cm−1.
Direct Photolysis of 2-Propanol Vapor
Authors: Herasymowych O. S. , Knight A. R.
Published: May 2006

The photolysis of 2-propanol vapor in the 1800–2000 Å wavelength range has been investigated. The volatile products of the reaction and their quantum yields at 80 °C and 200 Torr substrate pressure are H2 (0.64), CH3COCH3 (0.34), CH4 (0.39), CH3CHO (0.29), CO (0.15), and C2H6 (0.08). A mechanism is proposed that accounts for the observed rate variations with substrate pressure, exposure time, temperature, and pressure of inert addend. Acetone and acetaldehyde undergo significant secondary decomposition and this is the source of CO, CH4, and C2H6. Acetaldehyde is formed in the unimolecular decomposition of C3H7O radicals produced in the primary process.The effects of CO2 and CF4 as inert addends have been examined and it has been established that the quantum yield enhancement through collision induced predissociation that has been reported to occur in methanol is not a characteristic of the 2-propanol photolysis.
Thermolysis of Δ3-1,3,4-Oxadiazolin-2-ones
Authors: Lee S. L. , Cameron A. M. , Warkentin J.
Published: May 2006

Δ3-1,3,4-Oxadiazolin-2-ones are decomposed at moderate temperatures, either neat or in solution, by two parallel, first-order processes. One of these results in the formation of the appropriate diazomethane and carbon dioxide while the other leads to ketone, nitrogen, and carbon monoxide. Rates of these competing processes are reported along with some solvent effects and substituent effects on the product ratios.
The Relation between Contact Angle and Drop Size for Water at its Boiling Point for a Pressure Range 50–760 Torr
Authors: Ponter A. B. , Boyes A. P.
Published: May 2006

Contact angles have been measured using water drops of specified sizes, and in equilibrium with their vapor only, at their boiling point when residing on a copper surface at pressures ranging from 50–760 Torr.No appreciable change of contact angle with drop diameter was evident for sizes of 0.5 cm or more, but below this value the angles were dependent on the drop diameter, the effect of reducing pressure being to increase the dependency. The phenomenon is qualitatively explained in terms of gravity and surface roughness influences.
Preparation, Vibrational Spectra, Normal Coordinate Analysis, and Structures of bis-Pyridine and Orthophenanthroline Complexes of Mixed Halogenosilanes
Authors: Boal D. H. , Ozin G. A.
Published: May 2006

The compounds py2SiCl3X (where X = H, F, or Br), py2SiCl2X2 (where X = F or Br) and the corresponding orthophenanthroline complexes are prepared and the vibrational spectra reported for the first time. Using a combination of the vibrational data and normal coordinate calculations, the stereochemistries may be defined for most of the complexes. Preferences for certain configurations in the series are qualitatively discussed in terms of the spatial requirements of the various atoms and groups within each complex.
INDO–MO Calculations and Proton Isotropic Shifts of Methyl-Substituted Pyridine Ligands in Ni(II) Complexes
Authors: Sun M. S. , Grein F. , Brewer D. G.
Published: May 2006

Relative p.m.r. isotropic shifts for the ligands in the complexes NiL4(NO3)2 (L = 4-picoline and 3,5-lutidine), NiL3(NO3)2 (L = 3-picoline and 3,4-lutidine), and NiL2(NO3)2 (L = 2-picoline, 2,3-lutidine, 2,4-lutidine, and 2,5-lutidine) were determined in CDCl3. Proton hyperfine coupling constants for corresponding pyridine cations and analogous phenyl radicals were calculated by the INDO–MO method. Analysis of the p.m.r. shifts and subsequent correlation with the INDO data revealed that the spin transfer process between metal and ligand was dominated by a σ-mechanism, as indicated by ring protons at the α- and β-positions. The γ-ring proton and methyl protons at all positions indicated a π-mechanism was also operative through σ–π spin polarization at the nitrogen atom. The INDO calculations based on spin densities of the hydrogen Is orbitals, however, predicted that all ring protons would be dominated by a σ-mechanism, and that methyl protons at the α- and γ-positions should manifest a π-mechanism. Both mechanisms should be operative for the β-CH3 protons, with 50–60% σ-contribution in the pyridine cations and 30–50% σ-contribution in the phenyl radicals. The pattern of spin polarization (i.e., negative at α-C and γ-C, positive at β-C) is not altered by a small excess of α or β spin in the π-system. However, the π-spin density ratios, especially at the α- and γ-positions, are affected, as is the magnitude of the π-spin densities on each carbon. A comparison of the observed isotropic shifts for the methyl protons and for the γ-ring proton with the INDO calculated π-spin densities allows a determination of the spin delocalization in the ligand π-system.
Kinetics of Pentadienyl Cation Cyclizations
Authors: Bladek R. , Sorensen T. S.
Published: May 2006

A series of methyl-substituted pentadienyl cations has been prepared and characterized. A careful study was then made of the rate at which these cations cyclize to give cyclopentenyl cation products. Rate constants and activation parameters have been determined for this rearrangement in several different solvents and at several different cation concentrations. There is an unexpectedly large factor of 108 difference in rate between the extremes of the cations studied and a rationalization of this is presented.The cyclopentenyl cation products themselves undergo numerous rearrangements involving methyl or hydride shifts and a detailed discussion of the tetramethyl case is given. It is shown that a 3-cyclopenten-1-yl cation intermediate is involved in these rearrangements.
Sulfur-free Penicillin Derivatives. II. Functionalization of the Methyl Groups
Authors: Wolfe Saul , Lee Wha Suk , Ducep Jean-Bernard , Kannengiesser Gérard
Published: May 2006

Allylic bromination of anhydropenicillin chlorination products by N-bromosuccinimide (NBS) is described. With two molar-equivalents of NBS both methyl groups are functionalized; with one molar-equivalent of NBS a mixture of Z and E monobrominated isomers is obtained.Nitrogen and oxygen nucleophiles attack the dibrominated derivatives at the β-lactam carbonyl group, with concomitant ring-opening. However, the mono-brominated derivatives undergo ready displacement by azide and formate ions. The mechanism of these reactions, leading to preferred formation of Z-isomer, is discussed.Cyclization of the allylic formates yields sulfur-free derivatives corresponding to the cephalosporin Cc class of compounds.
Cyclopropylcarbinyl-oxo-carbonium Ions. Part V. Synthesis and Chemistry of some Cyclopropyl Glycopyranosides
Authors: Radatus Bruno , Fraser-Reid Bert
Published: May 2006

The synthesis of five cyclopropanated glycopyranosides, 6α, 6β, 7α, 7β, and 11 capable of providing access to the title ions has been examined. Simmons–Smith methylenation of methyl 4,6-O-benzylidene-2,3-dideoxy-α-D-eryrtro-hex-2-enopyranoside (8α) under carefully controlled conditions gives an excellent yield of the α-D-allo adduct (6α). A homoallyl iodide, 4,6-O-benzylidene-1,2,3-trideoxy-3-C-iodomethyl-D-ribo-hex-1-enopyranose, (9), is also produced and upon methanolysis undergoes ring closure to an equal mixture of α-D and β-D anomers of 6. Methylene insertion into the aglycon of the starting olefin 8α occurs giving small amounts of the ethyl hex-2-enopyranoside (10), the cyclopropanated glycoside derived therefrom, 11, being also obtained. Methylenation of the β-D-hex-2-enopyranoside, 8β, gives a complex mixture containing at least eight substances, although the expected β-D-manno adduct, 7β, is the major product. There is considerable anomerization of 8β and of the primary product, 7β; thus the anomer 7α is also produced. The 3-epimer (14) of the above-mentioned homoallyl iodide (9) is obtained in small yield.The cyclopronated glycosides are very susceptible to prolonged exposure to the Simmons–Smith medium. Particularly in the case of 8β the yields of the various products can be optimized by judicious choice of the duration of the reaction.Proton magnetic resonance data for the adducts are presented. The value of the spacing J34provides a clear basis for determining the configuration of the ring. However anisotropy due to the cyclopropane ring-current causes the equatorial H-1 in the β-D-manno-anomer (7β) to resonate at higher field than H-1 in the α-D anomer 7α.
Cyclopropylcarbinyl-oxo-carbonium Ions. Part VI. Synthesis and Chemistry of an Epimeric Pair of Homoallyl Iodides (3-Iodomethyl Glycals)
Authors: Fraser-Reid Bert , Radatus Bruno
Published: May 2006

The homoallyl iodide 4,6-O-benzylidene-1,2,3-trideoxy-D-ribo-hex-1-enopyranose, 4, is the second major product from Simmons–Smith reaction of methyl 4,6-O-benzylidene-2,3-dideoxy-α-D-erythro-hex-2-enopy-ranoside, 6α. The major product is the cyclopropyl glycoside 7α, which when treated separately with the Simmons–Smith reagents furnishes an 85% yield of 4. The mechanism of this transformation is investigated. It is not simply a Lewis-catalyzed iodinolysis since zinc iodide in a variety of solvents does not convert 7α to 4. Methylene iodide is essential, as is the organo-zincate complex, operative in Simmons–Smith reactions.The 3-epimer of the homoallyl iodide 4, i.e. 4,6-O-benzylidene-1,2,3-trideoxy-D-arbino-hex-1-enopyranose, 5, is produced in only 0.9% yield in the methylenation of the anomeric olefinic glycoside, 6β. The low yield is attributable to the extensive anomerization experienced by 6β itself, and by the primary reaction products. This leads to a plethora of compounds including both epimeric homoallyl iodides 4 and 5.In order to get it all together, the homoallyl iodide 4 is transformed into its epimer 5 by an unambiguous synthetic sequence. Some of the intermediates in this sequence are polyfunctional molecules of considerable synthetic potential.The possibility of an alternative route to compound 4 directly from the olefinic glycoside 6α is discussed. Coordination of the methoxyl oxygen of 6α to the organo-zincate complex could achieve an ideal SNi transition state in which [Formula: see text] is delivered at C-3 with synchronous departure of the methoxyl group. This mechanism, called the "reverse" allylic rearrangement for reasons outlined in the text, is discussed.
A New Synthesis of 6-Hydroxydopamine
Authors: Wehrli Pius A. , Pigott F. , Chu V.
Published: May 2006

An efficient synthesis of 6-hydroxydopamine is described. The key step involves oxidation of an N-protected 3-hydroxy-4-methoxyphenethylamine to the corresponding p-quinone by means of Fremy's salt.
Thermal Transformation in Anhydrous Rare Earth Acetates
Authors: Adachi G. , Secco E. A.
Published: May 2006

The thermal transformation in anhydrous acetates of Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu, and Y has been studied by thermal analysis. The enthalpy change, ΔH, and the entropy change, ΔS, accompanying the transformation process are reported and related to ionic radius of the rare earth element.The acetates of the rare earth elements, La, Pr, and Nd did not exhibit the thermal transformation property.
Metallation of N-Substituted β-Lactams. A Method for the Introduction of 3-Substituents into β-Lactams
Authors: Durst T. , LeBelle M. J.
Published: May 2006

N-Alkyl and N-aryl β-lactams yield lithio carbanions upon reaction with lithium diisopropylamide in tetrahydrofuran at −78°. These lithio salts react with a variety of electrophiles (e.g. ketones, esters, reactive alkyl halides) to give the 3-substituted derivatives in fair to good yield. The procedure is useful for the preparation of rather complex 3-substituted β-lactams from readily available simple derivatives.
Kinetics of Bromination of Acetone, Bromoacetone, and 1,1-Dibromoacetone
Authors: Cox Robin A. , Warkentin John
Published: May 2006

The rate of bromine consumption in acetate-promoted bromination of acetone is not measurably dependent on bromine concentration, in confirmation of earlier work. This result casts doubt on the existence of recently-reported, nonenolic mechanisms for bromination of butanone under similar conditions. The effects of alpha bromine substituents on rates of enolization of acetone are reported.
Assessment of Free Radical Catalysis in Thermal Methyl Isocyanide Isomerization. Variation of Inert Gas Efficiency with k/k∞
Authors: Fujimoto T. , Wang F. M. , Rabinovitch B. S.
Published: May 2006

Experiments have been made to assess the importance of radical chain effects in thermal isomerization of methyl isocyanide. Three bath gases, propylene, propane, and hexafluoroethane were studied at 230 °C over a small region of fall-off. The relative dilution with propane was varied widely. A negative search was made for possible secondary radical products. The values of K∞ accord with earlier results in the pure system. It is believed that radical catalysis is minor. The observed collisional efficiency of the inert gases [Formula: see text] decreases with increase of k/k∞, in accord with previous theoretical predictions.
Transient Response of the System Al/Al2O3/Electrolyte. Part I. Galvanostatic Transients
Authors: Goad D. G. W. , Dignam M. J.
Published: May 2006

Voltage transients under galvanostatic conditions are investigated for the system Al/Al2O3/electrolyte (glycol–borate) and the results, along with similar results obtained by Dewald for the system Ta/Ta2O5/electrolyte (0.1 N H2SO4), are analyzed according to the dielectric relaxation model due to Dignam. This model accounts for the general form of the transients, but systematic discrepancies are apparent. Modification of the model to include two independent ion-current-driven dielectric relaxation processes gives essentially exact agreement with the data and values for the constants in accord with those obtained earlier from potentiostatic transient measurements.
A Convenient Synthesis of L(+)-Muscarine
Authors: Whiting J. , Au-Young Y.-K. , Belleau B.
Published: May 2006

A new total synthesis of L(+)-muscarine is described. Performic acid oxidation of N-acetylcrotylglycine gave the corresponding 4,5-diol which was resolved at the α-carbon by stereospecific hydrolysis of the N-acetyl group of the L-isomer with hog kidney acylase I. The resulting α-L(+)-aminoacid diol (3; Chart 1) was deaminated with nitrous acid to give 4-hydroxy-5-methyl-2-tetrahydrofuran carboxylic acid with retention of configuration at position 2. Reaction of the corresponding methyl ester with dimethylamine gave two major amide constituents in 65% yield. Reduction of these two N,N-dimethylamides (5a and b) with lithium aluminum hydride followed by quaternization with methyl iodide afforded a pure isomer of L(+)-muscarine (6a) and L(+)-muscarine (6b) in high yields. The biological activity of the latter was the same as that of the natural alkaloid.
Equilibria Studies on Tetraalkylcyclopentenyl Cations. A Steric Origin for a Baker–Nathan Order?
Authors: Ranganayakulu K. , Sorensen T. S.
Published: May 2006

The possibilities of using observable cation equilibria to obtain evidence concerning C—H hyperconjugation are discussed. The experimental approach of this paper, using tetraalkylcyclopentenyl cation equilibria, is to vary the structure of the "normal" alkyl series in such a way that the hypothetical C—H hyperconjugative ability remains constant for a given series while the steric bulk of the groups changes. In fact, the observed equilibrium changes are minimal. Other experiments have been performed to measure both the effect of solvents on the equilibrium constants and the rate of the equilibration reaction. Still other experiments were designed to test the ability of H vs. CH3 in stabilizing alkyl cations and a value of ≥ 4.6 kcal/mol favoring CH3 has been found. Finally, the possibility of using structurally similar cation and anion equilibria to cancel out steric effects in these equilibria is discussed.
Two Diastereomeric Oxalatobis(S-butane-1,3-diamine)cobalt(III) Complexes
Authors: Parris M. , Dehayes L. J. , Busch D. H.
Published: May 2006

A study of the oxalatobis(S-butane-1,3-diamine)cobalt(III) system shows that the dissymmetric ligand imposes uniquely related geometric and configurational selectivity. The selectivity is in agreement with conformational prediction and the magnitudes of the Cotton effects lend some support to recently developed sector rules.
Photolysis and Thermolysis of Ethyl Diazomalonanilate and of 5-Hydroxy-1,4-diphenyl-1,2,3-triazole in Various Alcohols
Authors: Buu Nguyen Thanh , Edward J. T.
Published: May 2006

Ethyl diazomalonanilate was photolyzed in three alcohols (methanol, ethanol, and isopropanol) to produce the corresponding ethyl α-alkoxymalonanilates, ethyl alkyl α-N-phenylaminomalonates, and ethyl malonanilate. Thermolysis of the diazoanilide in ethanol and isopropanol yielded the same products as photolysis, but in lower yields. The yield of ethyl malonanilate increased with benzophenone sensitization.Photolysis and thermolysis of 5-hydroxyl-1,4-diphenyl-1,2,3-triazole in isopropanol produced α-isopropoxy-α-phenylacetanilide, isopropyl α-N-phenylamino-α-phenylacetate, and 2,5-diketo-1,3,4,6-tetraphenylpiperazine.Possible mechanisms for the decomposition of both compounds are discussed; an α-lactam may be an intermediate in the formation of the α-N-phenylamino esters.
The Elucidation of the Coupling Constants for the Cyclobutane Ring of the trans-Fused 2-Oxabicyclo[4.2.0]octane System
Authors: Servé M. Paul
Published: May 2006

The coupling constant for the fusion hydrogens of a bicyclo[4.2.0]octane ring system has been found using the shift reagent Eu(fod)3.