bluuebunny/crossref_metadata_2025 huggingface dataset:
Photochemistry of β-bromo-β-nitrostyrene
Authors: Shaffer G. W.
Published: May 2006

Ultraviolet irradiation of β-bromo-β-nitrostyrene in hydroxylic solvents gives a good yield of alkyl α-isonitrosophenyl acetates (1).
The conformation of some biaryl radicals
Authors: Laidlaw W. G. , Flewwelling R. B.
Published: May 2006

The conformations of the radicals of biphenyl, diphenylmethyl, and some of their methyl substituted derivatives were investigated by calculating the π-electron delocalization energy and the non-bonded repulsions between the rings. The barriers to rotation are also reported.
220 MHz spectra of heparin, chondroitins, and other mucopolysaccharides
Authors: Perlin A. S. , Casu B. , Sanderson G. R. , Johnson L. F.
Published: May 2006

Characteristics of proton magnetic resonance spectra of heparins at 220 MHz, coupled with spectral data for model compounds and with information obtained chemically, indicate that heparins are composed principally of (1 → 4)-linked α-L-idopyranosyluronic acid residues (3) and 2-amino-2-deoxy-α-D-glucopyranosyl residues (1); also, that sulfate groups are located at position -2 and -6 of 1, and -2 of 3. D-Glucopyranosyluronic acid residues (2) appear to be minor constituents, which is at variance with all structures that have been proposed previously for heparin.Spectra of chondroitins A, B, and C, which are readily distinguishable, are in close accord with formulae that have been proposed for these mucopolysaccharides; on the same basis, the spectrum of keratan sulfate is less consistent. Hyaluronic acid affords a poorly resolved though, nonetheless, distinctive spectrum. The general view that mucopolysaccharides are constituted basically of residues of hexosamine and uronic acid in equimolar proportion receives support from the current findings. However, heparitin appears to possess a more heterogeneous type of structure than do these other polymers.
Fischer indole synthesis. The reaction of N′-methyl-2,6-dimethylphenylhydrazine hydrochloride with 2-methylcyclohexanone and 2,6-dimethylcyclohexanone
Authors: Bajwa G. S. , Brown R. K.
Published: May 2006

When N′-methyl-2,6-dimethylphenylhydrazine hydrochloride (1) was heated with 2-methylcyclohexanone in refluxing dry benzene, the products isolated were ammonium chloride and methylammonium chloride (as a 1:1 mixture) as well as 1,8,9-trimethyl-1,2,3,4-tetrahydrocarbazole. The formation of these products was explained on the basis of the dienone-imine intermediate expected from the Fischer indole synthesis. The formation of methylamine hydrochloride indicated that at least one other route of reaction had occurred, in addition to that which provided the trimethyltetrahydrocarbazole and ammonium chloride.The hydrazine, 1, failed to react at all with 2,6-dimethylcyclohexanone under the reaction conditions employed.
Stereochemical aspects of the synthesis of 4-benzoyl-1,3-dimethyl-4-phenylpiperidine from 1,3-dimethyl-4-piperidone
Authors: Casy A. F. , Chatten L. G. , Khullar K. K.
Published: May 2006

1,3-Dimethyl-4-piperidone reacts stereospecifically with potassium cyanide to give the trans (3-Me/4-OH) cyanohydrin. This was converted to 1,3-dimethyl-4-hydroxy-4-diphenylhydroxymethylpiperidine which rearranged with zinc chloride – acetic anhydride to cis (3-Me/4-Ph) 4-benzoyl-1,3-dimethyl-4-phenylpiperidine. The stereochemistry of all the products was established from proton magnetic resonance (p.m.r.) data and from the properties of diastereoisomeric 4-benzoyl-4-phenylpiperidines prepared from isomeric 4-cyano-1,3-dimethyl-4-phenylpiperidines of known configuration. Stable epimeric (+NH) hydrochlorides of 4-carboxylate and 4-carbethoxy analogues of the cyanohydrin of 1,3-dimethyl-4-piperidone were detected in DMSO-d6 (p.m.r. evidence), and epimer formation in this series is discussed. The hot-plate activities in mice of some piperidine derivatives prepared during this work are reported.
Effet des anions sur la vitesse d'oxydation de la cyclohexanedione-1,2 par l'ion thallique
Authors: Favier R. , Zador M.
Published: May 2006

The effect of acetate, chloride, bromide, nitrate, and sulfate anions on thallic ion oxidation of 1,2-cyclohexanedione has been studied. Reactivities of the different complexes Tl(III)–anions have been determined. Generally introduction of a ligand in the internal coordination sphere of thallic ion produces an increase in the rate constant.
Radiation-induced oxidation of alcohols by TI(III) in acid aqueous solution
Authors: Burchill C. E. , Hickling G. G.
Published: May 2006

In deaerated aqueous perchloric acid solution TI(III) is reduced and 2-propanol oxidized to acetone in essentially equivalent yields by a γ-ray induced chain reaction. The yields increase linearly with increasing alcohol concentration in the range (1–8) × 10−2 M, are independent of TI(III) concentration in the range (1–4) × 10−3 M and vary inversely with the square root of the dose rate over the range 1.6 × 1017 to 1.8 × 1019 eV l−1 s−1. A mechanism is proposed to account for the observed stoichiometry and kinetic parameters.The same mechanism is found to apply to the reduction of TI(III) by methanol and ethanol. t-Butyl alcohol gives a much lower yield of TI(III) reduction and alcohol fragmentation products: acetone, methane, and ethane.
Structural features of a lipopolysaccharide isolated from Escherichiacoli 086:Kneg.
Authors: Singh Prem Pal , Adams G. A.
Published: May 2006

Lipopolysaccharide (LPS) prepared from Escherichiacoli 086:Kneg., in 5.5% yield contained D-galactose, D-glucose, L-fucose, L-glycero-D-manno-heptose, D-glucosamine, D-galactosamine, 2-keto-3-deoxy-octulosonic acid (KDO) and lipid A. The molecule appeared to be homogeneous as tested by free boundary electrophoresis, ultracentrifugation, and immunodiffusion against ′O′ specific E. coli antiserum. Methylation studies of the LPS and also of the degraded polysaccharides obtained by partial acid hydrolysis showed that the molecule was highly branched. Sixty percent of the D-galactose units were non-reducing terminal groups, the remainder were linked (1 → 3) and (1 → 2) and 3-O-β-D-galactopyranosyl-D-galactose was identified as a product of mild acid hydrolysis of the parent LPS. Fucose occurred in the polysaccharide as (1 → 4) linked units. Methylation results showed that the D-glucose units were linked (1 → 3) and (1 → 4). Partial acid hydrolysis yielded cellobiose, cellotriose, and laminaribiose, showing that the glucose units formed a glucan chain within the polysaccharide and that the glucosidic linkages were in the β-D-configuration. Approximately one half of the L-glycero-D-manno-heptose units occurred as non-reducing end groups, the other half were linked at C-3 and either one of C-6 or C-7. One half of the D-galactosamine units was linked (1 → 3) with the remainder occurring as double branch points. D-Glucosamine residues occurred exclusively in the lipid A moiety in a (1 → 4) linked core structure.
The 4-(methylthio)phenyl ester for the synthesis of polypeptides of a known repeating sequence of amino acids. Synthesis of poly-(L-lysylglycyl)glycine 1-C14 ethyl ester hydrobromide
Authors: Johnson Brian J. , Rea Donna S.
Published: May 2006

The synthesis of the tetrapeptide, N-t-butoxycarbonyl-ε-N-carbobenzoxy-L-lysylglycyl-ε-N-carbobenzoxy-L-lysylglycine 4-(methylthio)phenyl ester is described. The utility of this protective ester is shown by its easy conversion to the protected tetrapeptide 4-(methylsulfonyl)phenyl activated ester without decomposition. Removal of the N-butoxycarbonyl protecting group afforded the polymerizing unit, ε-N-carbobenzoxy-L-lysylglycyl-ε-N-carbobenzoxy-L-lysylglycine 4-(methylsulfonyl)phenyl ester. Polymerization of this material on the partially blocked monomer glycine-1-C14 ethyl ester hydrochloride, at a relatively high dilution, gave poly-(ε-N-carbobenzoxyl-L-lysylglycyl)glycine-1-C14 ethyl ester. The carbobenzoxy protective groups were removed to give the title compound.
Free-energy relationships in coordination chemistry. II. Requirements for linear relationships
Authors: Nieboer E. , McBryde W. A. E.
Published: May 2006

This paper discusses factors predisposing to linear free energy relationships among families of metal complexes. It is postulated that changes occurring at a reaction site in a test series of reactions and the corresponding changes in a reference series have their origins in the same independent variables. Linearity is seen to be favored when changes in the reaction site or in ligand substituents are small, and in the absence of strong interactions with the solvent. In addition to such considerations of a molecular sort, a number of relationships among the thermodynamic quantities ΔH0, ΔS0, and ΔG0 which have been identified as having a significant influence on rate and equilibrium relationships in series of organic reactions are discussed in terms of their effect on metal–ligand systems.
Structure of a product obtained on treatment of 1-thioacetoacetanilide with sulfuryl chloride
Authors: Curcumelli-Rodostamo M. , Harrison W. A.
Published: May 2006

Treatment of 1-thioacetoacetanilide with sulfuryl chloride or thionyl chloride produced a crystalline compound identified as 3,5-diacetonylidene-4-phenyl-1,2,4-dithiazolidine. The absence of carbonyl absorption in the infrared spectrum of the compound indicated that it should be represented by a resonance structure (2) involving non-carbonyl components.
Carbon-13 and proton chemical shifts of cyclohexanes in relation to interaction energy
Authors: Perlin A. S. , Koch H. J.
Published: May 2006

A comparison of nuclear magnetic resonance spectra for isomeric cyclohexane derivatives (methyl, hydroxyl, halogen) shows that net shielding of carbon-13 nuclei of these compounds increases additively with an increase in repulsive non-bonding interactions, and thus with decreasing enthalpy in the series. By contrast, an inverse shielding pattern is found for the appended protons. Hence, a destabilizing interaction in these compounds alters polarization of the C—H bond, placing greater electron density on carbon, and its impact appears to be delocalized over many C—H bonds of the molecule.
Methoxy group migrations in the reaction of some methyl-pyranoside chlorosulfate ester derivatives with aluminum chloride
Authors: Gibbs C. F. , Jennings H. J.
Published: May 2006

The treatment of methyl β-D-xylopyranoside 2,3,4-tri(chlorosulfate) with aluminum chloride yielded a mixture of two major components identified as methyl α-D-xylopyranoside 2,3,4-tri(chlorosulfate) and 4-O-methyl-α-L-arabinopyranosyl chloride 2,3-di(chlorosulfate). The latter compound constituted about 25% of the mixture and was formed as a result of the preferential migration of the anomeric methoxy group to C-4 of the pyran ring. Similar treatment of methyl α-D-glucopyranoside 2,3,4,6-tetra(chlorosulfate) with aluminum chloride yielded crystalline 6-O-methyl-α-D-glucopyranosyl chloride 2,3,4-tri(chlorosulfate) as the only major methoxy migration product. This methoxy migration occurred to the extent of 66% and in contrast to the results obtained with methyl pentapyranoside derivative the anomeric methoxy group migrated preferentially to C-6 in this case. The factors controlling these highly selective methoxy migrations are discussed.
Allyl radicals from 3,3′-azo-1-propene
Authors: Al-Sader Basil H. , Crawford Robert J.
Published: May 2006

3,3′-Azo-1-propene (4), 3,3′-azo-1-propene-3,3′-d2 (5) and 3,3′-azo-1-propene-3,3,3′3′-d4 (6) have been synthesized and characterized. Thermolysis of 4, at 40–300 Torr, and in the region 150–170°, followed first order kinetics (Ea = 36.1 ± 0.2 kcal mole−1, log A = 15.54 ± 0.10) the major product, >99.9%, being 1,5-hexadiene (9). The presence of less than 0.1% propene suggests that the allyl radical is unable to abstract hydrogen from 4 or 9. Statistical scrambling of deuterium, in the products of thermolysis of 5 and 6, was observed. These results are interpreted in terms of a mechanism wherein allyl radicals are generated. Comparison of the activation energies for azoalkanes and 4 with the bond dissociation energies of hydrocarbons suggest that a good Polanyi plot is possible.
ortho-Diquaternary aromatic compounds. III. Syntheses and reactions of polyalkyltetralones and derivatives
Authors: Barclay L. R. C. , Adams K. L. , Foote H. M. , Sanford E. C. , Young R. H.
Published: May 2006

A new synthesis is reported of polyalkyltetralones based on reactions of α,α-dialkylarylacyl chlorides with branched alkenes in the presence of stannic chloride. The following were synthesized by this method: 1,1,4,4-tetramethyl-2-tetralone (7a), 1,1,3,4,4-pentamethyl-2-tetralone (7b), 1,1,4,4,6-pentamethyl-2-tetralone (7c), 1,1-diethyl-4,4-dimethyl-2-tetralone (7d), and 3-keto-1,1,4,4-tetramethyl-1,2,3,4-tetrahydrophenanthrene (7e). Cyclialkylation of toluene with 2,2,5,5-tetramethyltetrahydrofuranone yielded 1,1,4,4,7-pentamethyl-2-tetralone. Monobromoderivatives were prepared from ketones 7a, b, and e and dibromoderivatives from ketones 7a and e. The polyalkyltetralones are used as intermediates in the synthesis of ortho-diquaternary aromatic compounds by various oxidative procedures.
Dissolution of bismuth metal by tri-iodide ion in acidified potassium iodide solution
Authors: MacDonald Digby D. , Wright G. A.
Published: May 2006

Dissolution of bismuth metal by tri-iodide ion in acidified potassium iodide medium has been studied using a rotating disc technique. The rate constant for the dissolution process, kT, in solutions 0.5 M in potassium iodide at 25.0 °C has been shown to be related to the square root of the disc angular velocity, ω, by the following expression[Formula: see text]The activation energy for this reaction was found to be 4.7 kcal mole−1. These data clearly establish that the rate of dissolution is determined by the rate at which tri-iodide ion is transported to the metal surface. In solutions of [KI] = 0.10 M, however, the rate determining step appears to involve diffusion of tri-iodide ion through a layer of BiI3 which forms on the bismuth metal surface as the reaction proceeds.
Benzene solvent induced shifts of the proton magnetic resonance spectra of some benzene derivatives. Importance of charge effects
Authors: Wasylishen R. , Schaefer T. , Schwenk R.
Published: May 2006

The benzene solvent shifts of the proton magnetic resonance spectra of numerous polysubstituted benzene derivatives are measured with respect to cyclohexane as reference solvent. For many of these compounds, an additive scheme can be devised in which the effect of a substituent, X, on the solvent shift, Δ, of a proton is given by Δix so that Δ = Σx, Σi Δix where i = ortho, meta, or para. There is a linear correlation of Δmx or Δpx with Taft's substituent constants σm0 and σp0. It is suggested that charge effects are much more important than steric effects in determining both the magnitude and sign of Δ.
Biosynthesis of lycopodine. Incorporation of Δ1-piperideine and of pelletierine
Authors: Castillo M. , Gupta R. N. , Ho Y. K. , MacLean D. B. , Spenser Ian D.
Published: May 2006

The biogenetic hypothesis that the Lycopodium alkaloids are modified dimers of pelletierine (2, 3) was tested experimentally in Lycopodiumtristachyum, Pelletierine is indeed incorporated into lycopodine, but only one pelletierine unit entered the alkaloid, rather than two units, as predicted. The hypothesis thus requires modification.Δ1-Piperideine serves as a specific precursor of lycopodine. Two Δ1-piperideine moieties are incorporated in such a way that the identity of C-2 and -6 of each of the precursor units is maintained.
Thermogravimetric analysis of Ontario limestones and dolomites. II. Reactivity of sulfur dioxide with calcined samples
Authors: Chan R. K. , Murthi K. S. , Harrison D.
Published: May 2006

Thermogravimetric analysis was done for representative calcined samples of Ontario limestones and dolomites in a 5% SO2 controlled atmosphere. The SO2 absorption vs. temperature curves showed three distinct regions. (i) A unimolecular chemisorption of SO2 at room temperature. (ii) An intermediate temperature region between 200–450 °C where absorption of SO2 was due to increased rate of SO2 diffusion into the interior of CaO via grain boundaries. When the surfaces of these internal spaces were almost fully occupied the rate of SO2 absorption decreased. Further absorption was due to diffusion of SO2 into CaO lattice, which was a much slower process. (iii) A fast absorption region between 500–700 °C, where a disproportionation of CaSO3 into CaSO4 and CaS took place which effectively broke down the original CaO structure to expose fresh layers of CaO. The amount of SO2 absorption after 1 h at 745 °C corresponded to approximately 80% conversion of CaO to mainly CaSO4 and CaS and smaller amount CaSO3.Finally, the calculations showed that the reaction of SO2 with CaO was more exothermic than the reaction of SO2 with MgO, which accounted for the faster rate of the former.
Crystallographic studies of cobalt arsenates II. Crystal structure of Co8As3O16
Authors: Krishnamachari N. , Calvo C.
Published: May 2006

CO8AS3O16, the Co analogue of the mineral aerugite, crystallizes in the rhombohedral space group [Formula: see text] with hexagonal unit cell parameters a = 6.046(1) and c = 28.062(8) Å, and Z = 3. The structure has been refined by a full matrix least squares technique using 613 reflections to a final R value of 0.080. The cations are in tetrahedral and octahedral interstices between layers of oxygen atoms nearly showing cubic closest packing. The structure has one third of the As ions in sites of point group symmetry [Formula: see text] with a nearly perfect octahedral environment of oxygen atoms. The remaining As ions lie in sites having the point group 3m and showing tetrahedral coordination to oxygen atoms. In the former case the mean As—O bond length is 1.84 Å while in the latter case it is 1.68 Å. The Co ions lie in positions having either 2/m or m symmetry with a mean Co—O bond length of 2.13 Å in each case. All the atoms have at least mirror symmetry about them. Some deviation from stoichiometry has been found and may indicate that some of the cobalt has been oxidized.
Coordination complexes of gallium(III) and indium(III) halides. VI. The structures of gallium(III) halide complexes with 1,10-phenanthroline
Authors: Carty A. J. , Dymock K. R. , Boorman P. M.
Published: May 2006

Reaction of 1,10-phenanthroline (phen) with gallium trihalides yields the complexes GaX3(phen) (X = Cl, Br, I), GaX3(phen)2 (X = Cl, Br), and GaX3(phen)3 (X = Br, I). Raman and infrared measurements have established the structures of these compounds as [GaX2(phen)2][GaX4], [GaX2(phen)2]X, and [Ga(phen)3]X3. GaI3(bipy) (bipy = 2,2′-bipyridyl) has the structure [GaI2(bipy)2][GaI4]. Raman and far-infrared measurements allow ready identification of GaX4− ions in these systems. The stereochemistry of the cation [GaX2(phen)2]+ cannot be established from vibrational data alone.
Isobutane from acid-catalyzed dehydration of butanols
Authors: Warkentin John , Hine Kenneth E.
Published: May 2006

Dehydration of the four isomeric butanols by strong acid at about 160° gives a C4-fraction containing isobutane as well as the isomeric butenes. Isobutane probably arises by hydride transfer, from one or more donors including the substrate alcohol and hydrocarbons formed from it in the medium, to one or more carbonium ions including the t-butyl cation. Materials which react with 2,4-dinitrophenylhydrazine reagent to form 2,4-dinitrophenylhydrazones can be swept out of the hot acid solution with a stream of nitrogen.
Reactions of trifluoromethyl and methyl radicals with ethylene oxide
Authors: Jones S. H. , Whittle E.
Published: May 2006

The reaction between CF3 radicals and ethylene oxide was studied in the range 60–228 °C using CF3I as a radical source. For the reactions,[Formula: see text]we obtain[Formula: see text]where θ = 2.3 RT kcal mole−1Published data of Phibbs and Darwent on the reaction[Formula: see text]have been re-calculated and it is suggested that both the original and re-calculated values of the activation energy E5 are too low. The Arrhenius parameters for the reactions of CF3 and CH3 radicals with ethylene oxide are compared with those for related reactions.
The reaction of atomic hydrogen with methyl cyanide
Authors: Jamieson J. W. S. , Brown G. R. , Tanner J. S.
Published: May 2006

The reaction of hydrogen atoms, produced by electric discharge, with methyl cyanide vapor has been reinvestigated at seven different temperatures between 40 and 507 °C over a range of methyl cyanide flow rates from 2 to 25 μmoles/s. As in the previous limited investigation the products have been found to be hydrogen cyanide, methane, and ethane, but the present results indicate the presence of chain characteristics to a minor extent, propagated by CN. Kinetic parameters for formation of the products have been evaluated, as kHCN = 3.55 × 10−12 e−5816/RT; [Formula: see text]; and [Formula: see text].
Studies related to the mechanism of action of cardiac glycosides. On the reactions of thiols with unsaturated lactones and on the structure of the compound previously reported as ouabagenin. The preparation and properties of authentic ouabagenin
Authors: Jones J. Bryan , Middleton Hugh W.
Published: May 2006

In connection with mechanism of action studies on cardiac glycosides, the reactions of α-pyrone, γ-crotonolactone, digitoxigenin, and ouabagenin have been studied. No Michael addition reactions were observed with the cardenolide aglycones. The compound previously reported in the literature as ouabagenin has been shown to be 1β,3β,5β,11α,14β,19,21-heptahydroxycard-20,22-enoic acid and the preparation and properties of authentic ouabagenin are described.
An electron spin resonance study of the mechanism of intermolecular cation exchange reactions
Authors: Gough T. E. , Hindle P. R.
Published: May 2006

A survey of the effects, as detected by electron spin resonance spectroscopy, of adding NaX (X− = Ph4B−, ClO4−, I−) to sodium-semiquinone ion pairs is given. When X− = Ph4B− triple ion formation was observed, but when X− = ClO4− or I− intermolecular cation scrambling occurred. It is postulated that such scrambling reactions proceed via the triple ion.
An hydration scale for ketones in polar aprotic solvents
Authors: Stewart Ross , Dyke John D. Van
Published: May 2006

An hydration scale (W0) for aqueous sulfolane and dimethyl sulfoxide (DMSO) has been developed that represents the effect of the solvent on the equilibrium hydration of a series of trifluoroacetophenones; [Formula: see text]. The equilibrium constants are correlated with the substituent parameter σ+; ρ+ = −1.62 for dehydration. The function W0, defined as [Formula: see text] is zero for pure water and rises to a value of 2.72 in 99 mole% sulfolane. W0 in aqueous DMSO is negative from 0 to 85 mole% DMSO, meaning that these systems hydrate the ketones to a greater extent than does pure water.
Formation, Structure, and Properties of Nitrosonium and Nitronium Fluorosulfate
Authors: Qureshi A. M. , Carter H. A. , Aubke F.
Published: May 2006

The reactions of the nitrogen oxides, N2O, NO, N2O3, NO2 (N2O4), and N2O5, the oxychlorides ClNO and ClNO2, and the oxyanions NO2− and NO3− with the fluorosulfonating agents S2O6F2 and BrOSO2F are studied systematically in regard to the formation of nitrosonium and nitronium fluorosulfate. Complex reactions are found when N2O3 and N2O4 are used as substrates, resulting in mixed or impure products. An explanation involving the intermediate oxidation into N2O5 is put forward to explain the results.The solid products NOSO3F and NO2SO3F are characterized by powder X-ray analysis, infrared and Raman spectroscopy, and their solution behavior in HSO3F. Whereas NOSO3F has been found to have an orthorhombic lattice, NO2SO3F crystallizes in the monoclinic system. Unit cell parameters are reported. The vibrational spectra are interpreted in terms of ionic compounds NO+SO3F− and NO2+ − SO3F−. The SO3F− anion, however, appears to be perturbed and all the E modes are slightly split. No unambiguous evidence for a previously reported non-linear NO2+ cation is found. Force constants for this species are calculated assuming D∞h symmetry.Both compounds are found to be completely dissociated in HSO3F as evidenced by conductometry and 1H and 19F nuclear magnetic resonance (n.m.r.) spectroscopy.
Diffusion of Methane and Chloromethanes in Air
Authors: Cowie M. , Watts Harry
Published: May 2006

The binary gaseous diffusion coefficients of air with methane, methyl chloride, methylene chloride, chloroform, and carbon tetrachloride at 298.2 °K and 1 atm have been determined. A simple diffusion cell was used, in which concentration changes of the diffusing gas were followed by infrared spectrophotometry.
The Radiolysis of Gaseous DCl
Authors: Jardine D. K. , Armstrong D. A. , Boyd A. W. , Willis C.
Published: May 2006

The value of G(D2) from the radiolysis of gaseous DCl is 7.4 ± 0.3 at dose rates of 1015 and 1027 Ev g−1 s−1. The yield of hydrogen (D2, H2, or HD) from electron reactions and the unscavengeable yield are, within experimental error, the same as in HCl. However, fewer thermal hydrogen atoms are formed in primary processes and a greater proportion of the electrons produce clustered negative ions ((DCl)−(c)) than in HCl. The magnitude of [Formula: see text] at 288 K is a factor of three smaller than [Formula: see text] at the same temperature.
La réaction des nitrilotriacétates métalliques avec la proline
Authors: Israeli J. , Cayouette J. R.
Published: May 2006

not available
A Technique for Determining Proton Chemical Shifts arising from Ring Current Effects: the Conformations of Triply Ortho-substituted Diphenyl Ethers
Authors: Bergman J. J. , Chandler W. D. , Moir R. Y.
Published: May 2006

A double-difference technique, making it possible to obtain that part of proton chemical shifts that originates in the shielding by the second ring in diphenyl compounds, is discussed. Evidence in support of the theory comes from the chemical shifts of aromatic ring protons in a family of triply ortho-substituted diphenyl ethers. The conformations of these ethers appear to be independent of the ortho-substituent, X (X ≠ H), and the COC angle is shown to be approximately 120°.
Alkaloids of Tabernaemontana psychotrifolia H.B.K.
Authors: Burnell R. H. , Medina J. D.
Published: May 2006

A new alkaloid C20H24N2O (taberpsychine) obtained from Venezuelan T. psychotrifolia is shown to have structure 5. The Hofmann degradation products of taberpsychine and its dihydro derivative are discussed. Two other bases isolated are affinine and 16-epi-vobasinic acid, the latter for the first time as a natural product.
Substituent Effects on the Orientation of Diels-Alder Reactions. II
Authors: Schmidt Cirill , Sabnis S. D. , Schmidt Edith , Taylor D. K.
Published: May 2006

The competitive ortho directing (c.o.d.) influence of a 1-methoxy group and a 4-methyl group and a 4-methyl was studied in the Diels–Alder addition of 1-methoxy-1,3-pentadiene (1) to 2,6-dimethylbenzoquinone (2). It was found that the c.o.d. influence of a terminally located methoxy is stronger than the effect of a terminal methyl group in the diene since only adduct 3 could be isolated. The influence of non-terminal substituents compared to terminal substituents in diene appears to be insignificant. This was demonstrated by obtaining only adduct 5 form the addition of 3-ethoxy-1,3-pentadiene (4) with 2,6-dimethylbenzoquinone (2). The following order of c.o.d. influence was suggested in the diene relative to a methyl group in the dienophile OCH3 > CH3 > H.
The Raman Spectra of the Chlorofluorosilanes in the Gaseous, Liquid, and Solid State; Anomalous 35Cl, 37Cl Isotope Intensity Effects in the Splitting of the Totally Symmetrical SiCl Stretching Mode in SiCl3F and SiCl2F2
Authors: Hamada K. , Ozin G. A. , Robinson E. A.
Published: May 2006

The Raman spectra of the chlorofluorosilanes are reported in their various phases together with vibrational assignments of the normal modes. The 35Cl–37Cl isotope lines of the totally symmetrical SiCl stretching modes in SiCl3F and SiCl2F2 were partially resolved in the solid and liquid phases and their intensities were found to be approximately normal in the liquid state but may show deviations in the solid state. Possible reasons for this behavior are discussed and the results are compared with similar effects observed for CCl3F and CHCl3.
Model Calculations on the Energy Levels of Diatomic Anharmonic Oscillators: Relation to Hydrogen Bonding
Authors: Foldes A. , Sandorfy C.
Published: May 2006

Vibrational frequencies and anharmonicity constants for diatomic anharmonic oscillators are obtained by model calculations based on the conventional potential function[Formula: see text]
The Thermal Pressure and Energy–Volume Coefficients of Dimethyl Sulfoxide – Water Mixtures
Authors: Macdonald Digby D. , Hyne J. B.
Published: May 2006

Thermal pressure and energy–volume coefficients are reported for several DMSO–water mixtures over the temperature range 13–55 °C. The energy–volume coefficient at 25 °C is found to pass through a maximum at 0.3–0.4 mole fraction DMSO and this observation is rationalized in terms of maximization of intercomponent interactions. The relationship between the energy–volume coefficient and the cohesive energy density of the binary liquid system is examined. The temperature dependence of the thermal pressure coefficient is discussed in terms of the effect of temperature on the susceptibility of the entropy of DMSO–water mixtures to isothermal expansion.
Sulfur Dioxide Insertion Reactions of some Compounds containing Sn—C and Fe—Sn—C Bonds
Authors: Edmondson R. C. , Field D. S. , Newlands M. J.
Published: May 2006

The preparations of [CpFe(CO)2]2Sn[OS(O)Ph]2, CpFe(CO)2SnPh[OS(O)Ph]2, CpFe(CO)2SnPh[OS(O)Ph]OH, and Ph2Sn[OS(O)Ph]2 by sulfur dioxide insertion into the C—Sn bond and also by reaction of the sodium phenyl sulfinate with the corresponding chloro-compounds are reported. The infrared (i.r.) spectra and some reactions of these compounds are also discussed.
Competitive Reactions in the Thermal Decomposition of Cellulose
Authors: Arseneau Donald F.
Published: May 2006

Further evidence is presented to show that when cellulose is heated it undergoes two competitive reactions. The actual sequence of these is clarified, being different from that previously postulated. The natures of these reactions are studied, activation energies are determined, and their possible mechanisms are suggested. The thermogram for levoglucosan decomposition is given and briefly discussed.
Synthesis of 1-Substituted Derivatives of Anhydro(3-chloroacety1-2-hydroxyimidazo [1,2-a]pyridinium Hydroxide)
Authors: Anderson Wayne K. , Friedman Alan E.
Published: May 2006

The reaction of chloroacetic anhydride and chloroacetic acid with N-substituted 2-aminopyridine derivatives 3 produced 1-substituted derivatives of anhydro(3-chloroacetyl-2-hydroxyimidazo[1,2-a]-pyridinium hydroxide) (4). The isomeric anhydro(1-benzyl-2-chloroacetyl-3-hydroxyimidazo[1,2-a]-pyridinium hydroxide) (10a) was prepared by a reported procedure and the spectral data of the two isomeric series of compounds were compared. The significant differences in the n.m.r. spectra of the two series were attributable to the deshielding influence of the exocyclic acyl moiety.
Osmotic and Activity Coefficients of Some Simple Borate Solutions at the Freezing Point
Authors: Platford R. F.
Published: May 2006

Activity coefficients for aqueous sodium and potassium tetraborate, sodium metaborate, sodium and potassium fluoroborate, and orthoboric acid were derived from their freezing points. The measurements confirmed in general the behavior of these salts at 25° except that the tetraborates showed different low concentration behavior from that predicted from isopiestic data. Because of this difference, the 25° activity coefficients reported earlier for sodium and potassium tetraborates have been revised. The new values for 0.15 m solutions of the tetraborates are 0.345 at 25° and 0.303 at the freezing point.
Electron Spin Resonance Spectra of Radicals Produced in the Thermal Reaction of Benzophenone with Triphenylsilane
Authors: Mcintosh A. R. , Wan J. K. S.
Published: May 2006

Thermal reaction of benzophenone with triphenylsilane at 400 °K produced an electron spin resonance (e.s.r.) spectrum which is interpreted due to the triphenylsiloxydiphenylmethyl radical, Ph2ĊOSiPh3.
Influence of pH on the Kinetics of Hydration of Tricalcium Silicate
Authors: Mccurdy K. G. , Erno B. P.
Published: May 2006

An investigation has been made of the influence of pH on the kinetics of hydration of tricalcium silicate in a large excess of water. The rate constants increase with increasing hydrogen ion activity [Formula: see text] in the liquid phase when the [Formula: see text] is low; however, as the [Formula: see text] is increased further the rate constants become independent of the[Formula: see text] The results have been interpreted by proposing that the rate constants are proportional to the hydrogen ion activity adsorbed, [Formula: see text] on the solid surface. The Langmuir adsorption isotherm was used to correlate the hydrogen ion activity on the surface to the hydrogen ion activity in the liquid phase.Several particle sizes of tricalcium silicate were investigated and a surface area effect is indicated.
The Chlorination of Pyrroles. Part II
Authors: Birchall G. R. , Rees A. H.
Published: May 2006

We report the chlorination of pyrryl-2-glyoxylic acid and derivatives and hence a synthesis of O,O′-dimethylpyoluteorin and 5-dechloro-O,O′-dimethylpyoluteorin. The different behavior of these compounds on demethylation is described and explained.
Utility of Shift Reagents in Nuclear Magnetic Resonance Studies of Polyfunctional Compounds: N- and O-Acetylated Carbohydrates and Nucleosides
Authors: Butterworth R. F. , Pernet A. G. , Hanessian S.
Published: May 2006

The utility of n.m.r. shift reagents, Eu(DPM)3 and Pr(DPM)3, can be extended to polyfunctional molecules containing acetate and amide groups with significant spectral simplification and definitive peak assignments based on "signal crossover" phenomena.
Pyrrole Chemistry. Part XII. The Mechanism of the Reaction Between the Pyrrole Grignard Reagent and Acylating Agents
Authors: Loader C. E. , Anderson Hugh J.
Published: May 2006

Deuterium labeling experiments have shown that, in the reaction between the pyrrole Grignard reagent and methyl 1-pyrrolecarboxylate to form 1,2′-dipyrrolyl ketone, direct acylation occurs at the 2-position of the pyrrole Grignard reagent, rather than initial substitution onto the 1-position, followed by rearrangement to the 2-position. At an intermediate stage in the formation of the ketone, ring interchange takes place between the 1-substituted pyrrole rings in the intermediate and unused Grignard reagent, and as a result both pyrrole rings in the final product may originate from the Grignard reagent.
Structure of the Second Coordination Sphere of Transition Metal Complexes. II. Substituted Anilines as Ligands
Authors: Eaton D. R. , Ohorodnyk H. O. , Seville Linda
Published: May 2006

The role of substituted anilines as second coordination sphere ligands of cobalt(II) complexes has been investigated. Chemical shifts of the ligand nuclear magnetic resonance (n.m.r.) spectra arising from pseudo-contact interaction with the paramagnetic cobalt complex have been utilized for this purpose. It has been found that in each case the aniline preferentially occupies a position perpendicular to the three fold symmetry axis of the complex and tends to be aligned with the amino group directed towards the cobalt atom. Electron withdrawing substituents para to the amino group enhance the second coordination sphere binding and electron donating substituents diminish it. These results are consistent with the idea that the structure of the second coordination sphere is determined by electrostatic interaction with the negatively charged ligands comprising the first coordination sphere. There is competition between aniline molecules and solvent molecules for a position in the second sphere with the solvent competing with increasing effectiveness in the series carbon tetrachloride, benzene, and methylene chloride.
Photolysis of 4-Methyl 3-Hexanone and 2-Methoxy 3-Pentanone in Hydrocarbon Solution
Authors: Lee L. P-Y. , McAneney B. , Guillet J. E.
Published: May 2006

Studies of the photolysis of 4-methyl 3-hexanone and the iso-electronic 2-methoxy 3-pentanone have been made in hydrocarbon solution using light of wavelength 313 nm. The latter compound gives only Norrish type II products with a quantum yield of 0.19 ±.01. The former gives a predominance of type I products with a total quantum yield of 0.23 ±.01 and the quantum yield for type II is reduced to 0.10 ±.01. The predominant type I reaction appears to involve α-scission to give an ethyl and a 2-methyl butyryl radical, which suggests a "cage effect". It is suggested that the reason for the suppression of the type I reaction in 2-methoxy 3-pentanone is the greater ease of γ-hydrogen abstraction due to the presence of the oxygen atom in a six-membered transition state.
Oxidation of Pentoses in Alkaline Solution
Authors: Gleason W. B. , Barker R.
Published: May 2006

The reaction of pentoses with oxygen in dilute aqueous potassium hydroxide at 25.00 ± 0.05° has been studied by determining the initial rate of oxygen uptake and the rate of disappearance of reducing sugar. Pentose reactivity decreased through the series: D-xylose (2.0), D-ribose (1.4), L-arabinose (1.2), D-lyxose (1.0). The products formed were identified by paper chromatography, isolation, and n.m.r. spectroscopy. In all cases less than one molar equivalent of tetronic acid is produced. The results are discussed with reference to recent studies on the behavior of sugars in alkaline solution. The reaction of pentoses with oxygen in 0.5 M sodium carbonate at 25.00 ± 0.05° was also studied. The order of pentose reactivity in this system was changed to D-ribose (5.7), D-lyxose (2.2), D-xylose (1.9), L-arabinose (1.0).
Anharmonicity and Hydrogen Bonding. The in-plane OH Bending and its Combination with the OH Stretching Vibration
Authors: Asselin M. , Sandorfy C.
Published: May 2006

The infrared spectra of isopropanol, tert-butanol, and their deuterated homologues were measured between 1600 and 1160 cm−1 in a mixture of CCl3F and methylcyclohexane-d14 at temperatures ranging from 20 to −182 °C. The assignments of the in-plane OH deformation (δOH) bands of alcohols are confirmed by these low temperature measurements. An explanation is proposed for the great apparent differences between the δOH frequencies of primary and secondary alcohols on the one hand, and tertiary alcohols on the other. The effect of temperature on the δOH frequency of hydrogen bonded alcohols is found to be slight. Hydrogen bonding increases significantly the anharmonic coupling constant between νOH and δOH It remains, however, much smaller than the anharmonicity constant of νOH itself.
Photolysis of 1,1-Diphenylsilacyclohexanone in Diethyl Fumarate. The Trapping of a Siloxycarbene by an Electron-Deficient Olefin
Authors: Brook A. G. , Kucera H. W. , Pearce Ronald
Published: May 2006

Photolysis of diphenylsilacyclohexanone in diethyl fumarate yields a product shown to be the cyclopropane resulting from trapping of a siloxycarbene by the alkene.
The Reaction of Hydroperoxides with Triphenylphosphine
Authors: Hiatt R. , Smythe R. J. , McColeman Christine
Published: May 2006

The reductions of n-butyl, sec-butyl, and tert-butyl hydroperoxides by triphenylphosphine in ethanol have been shown to follow second-order kinetics with k2's equal, respectively to 107.2e−8.4/RT, 109.0e−10.8/RT, 108.8e−11.2/RT. Similar results obtain in CH2Cl2, but in hexane the rate equation requires an additional term, k3[Ph3P][RO2H]2, though the overall reaction is somewhat faster than in the other solvents.Retardation, apparently by adventitious impurities, has been observed in some cases, but attempts to inhibit the reaction by free radical traps were unsuccessful. Parallels with reduction of hydroperoxides by organic sulfides suggest a similar non-radical mechanism.
Cobalt(II) Complexes of Isothiazole
Authors: Rivest R. , Weisz A.
Published: May 2006

The preparation and spectral properties are reported for complexes of CoX2 (X = Cl, Br, I) and Co(ClO4)2 with isothiazole (L). The following complexes have been prepared: CoL2X2, CoL4X2, and CoL6(ClO4)2. In the solid state, CoL2X2 (X = Br, Cl) are octahedral and polymeric, CoL4X2 (X = Br, Cl) are octahedral, CoL2I2 is tetrahedral, [CoL6](ClO4)2 is octahedral. Except for [CoL6](ClO4)2 which remains octahedral, all the other complexes give solutions in which Co(II) has a tetrahedral environment. In all the complexes, the ligand L is N-bonded to cobalt(II).
Nuclear Magnetic Resonance Evidence Concerning the Effect of Remote Polar Substituents upon Conformational Equilibrium in Substituted Ethanes
Authors: Hamer G. K. , Reynolds W. F. , Wood D. J.
Published: May 2006

The vicinal coupling constants of 1-(4-X-phenyl)-1,2-dibromoethanes vary with substituent. The coupling constants correlate with parameters which measure the polarity of the C—X bond. It is concluded that the observed changes in coupling constants with substituent are due to electrostatic interactions between the C—X and C2—Br bonds. Two different types of electrostatic calculations confirm that this interaction should stabilize the rotamers in which the phenyl and C2—Br groups are in a gauche orientation when the C—X group has polarity Cδ+—Xδ−.
Occurrence and Origin of the Tropylium Ion in the Mass Spectra of Arylboronic Acid Esters
Authors: Bose R. J. , Peters M. D.
Published: May 2006

The mass spectra of a number of phenylboronic acid esters of 1,2- and 1,3-diols are examined and the presence and origin of the tropylium rearrangement ion is established.
Electron Spin Resonance Studies of the Radiolysis of Aliphatic Amines at 77 °K
Authors: Wardman P. , Smith D. R.
Published: May 2006

Several frozen aliphatic amines have been γ-irradiated at 77 °K and the electron spin resonance (e.s.r.) spectra of the trapped radicals obtained at 77 °K and on warming. Radiolysis of methyl, ethyl and isopropyl amines produces predominantly alkylamino [Formula: see text] radicals. The proton hyperfine (h.f.) couplings of [Formula: see text] radicals are 10–30% larger than those in the corresponding isoelectronic alkyl radicals and the parallel component of the 14N coupling is about 35 G. Restricted rotation of alkyl groups occurs at 77 °K in some cases. On warming from 77 °K, the [Formula: see text] radicals generally abstract from the solvent or isomerize to produce radicals of the aminoalkyl type (e.g. RĊHNH2). The alkyl proton h.f. splittings of these latter radicals are 20–40% lower than in the corresponding alkyl radicals, and the observed 14N coupling was [Formula: see text] in ĊH2NR2 and [Formula: see text] in (CH3)2ĊNH2 and CH3ĊHNH2. The amino proton couplings in the aminoalkyl radicals were not resolved. Irradiated dimethylamine produces both (CH3)2N and CH2N(CH3) radicals, but (CH3)2N disappears on warming. Only ĊH2N(CH3)2 was observed after irradiation of (CH3)3N at 77 °K. Solid methoxyamine (giving CH3ONH) and tert-butyl-amine were also studied.
Alkaloids of Certain Oriental Ormosia Species
Authors: Mclean Stewart , Lau P. K. , Cheng S. K. , Murray D. G.
Published: May 2006

The basic extracts of five oriental Ormosia species (O. sumatrana, O. emarginata, O. indurata, O. semicastrata, and O. pachycarpa) have been examined and N-methylcytisine, N-methyltetrahydrocytisine, ormosanine, 18-epiormosanine, and racemic piptanthine have been isolated and identified. A further alkaloid of formula C20H33N3, which does not appear to have been described previously, has been isolated from O. semicastrata.
Proton Magnetic Resonance Studies of Rotational Isomerism in Halotoluenes VIII. Stereospecific 1H–9F Coupling Constants and Conformations of some Fluoro and Chloro Derivatives of Benzalchloride
Authors: Hutton H. M. , Rowbotham J. B. , Barber B. H. , Schaefer T.
Published: May 2006

In solution the 2-fluoro-5-chloro-, 2-fluoro-6-chloro-3-nitro-, 2-fluoro-6-chloro-5-nitro-, and 2,4,5-trichloro-benzalchlorides prefer conformations in which the C— bond of the side-chain lies in the plane of the aromatic ring. This C—H bond eclipses that ortho C—X bond (X = H, F, Cl) in which X is smaller than Y = H, F, Cl in the C—Y bond, also ortho to the dichloromethyl group. The long-range spin–spin coupling constants between the proton in the side-chain and the ring protons or fluorine nucleus are stereospecific. In particular, the coupling over four bonds between the side-chain proton and the ring fluorine is −0.3 Hz when the C—H and C—F bonds are arranged cis to each other but is −2.5 Hz when these bonds have a transoid planar arrangement.
The Excited Singlet State of Chloropentafluoroacetone; Quenching by Unsaturated Hydrocarbons
Authors: Samant H. S. , Yarwood A. J.
Published: May 2006

The fluorescence of chloropentafluoroacetone in the gas phase at 23 °C is quenched by the addition of certain olefins. The quenching rate constants of 17 unsaturated hydrocarbons for the first excited singlet state of chloropentafluoroacetone are reported. The molecules are divided into two classes on the basis of their quenching abilities, (a) olefins with only electron-withdrawing substituents and (b) olefins with electron-donating substituents. It is shown that the quenching by molecules in the latter group can be quantitatively correlated with the ionization potential (i.p.) of the quenching molecule. The relation is log k = 18.0 − 0.79 (i.p.), i.e. a type of linear free energy relation is obeyed. This implies that the quenching by molecules containing only electron-donating substituents involves a charge-transfer complex.
Nuclear Magnetic Resonance Studies. XXIII. Long-range 1H–1H Couplings (JHCCOCH) in some Methyl Bicyclo[2.2.1]heptane-2-carboxylates
Authors: Brouwer H. , Stothers J. B.
Published: May 2006

The methoxyl proton signals of several 3-substituted 2-carbomethoxybicyclo[2.2.1]hept-5-enes and -heptanes appear as doublets because of 1H–1H coupling over five σ-bonds (5J). The dependence of these long-range coupling constants on the nature and orientation of 2- and 3- substituents is discussed in terms of the probable conformations of the 2-carbomethoxyl groups.
The Acetone – Acetic Anhydride – Carbon Disulfide System: Surface Tension, Viscosity, and Total and Partial Vapor Pressures
Authors: Campbell A. N. , Kartzmark E. M. , Anand S. C.
Published: May 2006

The surface tensions, viscosities, and vapor pressures, total and partial, have been determined as functions of concentration for the following systems: (a) acetone – acetic anhydride; (b) acetone – carbon disulfide; (c) acetic anhydride – carbon disulfide; and (d) pseudo-binary mixtures of (a) and (b), whose compositions lie on a straight line tangential to the plait point of the ternary system.The general behavior of ideal and non-ideal systems, in regard to surface tension and viscosity is discussed. For the system acetone – carbon disulfide, whose vapor phase can be considered ideal, the activities, activity coefficients, excess free energies, enthalpies and entropies of mixing have been obtained from the vapor pressures. The vapor phase of the other three systems contains acetic anhydride which is associated in the vapor state, and for these systems the experimental data are reported without further calculation.
Synthesis of (RS)-Abscisic Acid
Authors: Findlay J. A. , MacKay W. D.
Published: May 2006

New approaches to the abscisic acid synthetic precursor 4 and the abscisic acid analog 6 are reported.
Pyrrole Chemistry. Part XIII. New Syntheses of 3-Alkylpyrroles
Authors: Groves J. K. , Anderson Hugh J. , Nagy H.
Published: May 2006

3-n-Alkylpyrroles are prepared in good yield by a combined Wolff-Kishner reduction and hydrolysis and decarboxylation of 4-acyl-2-pyrrolethiolcarboxylates. Methyl 4-isopropyl-2-pyrrolecarboxylate and 4-t-butyl-2-pyrrolecarbonitrile are prepared by alkylation of methyl 2-pyrrolecarboxylate and 2-pyrrolecarbonitrile respectively. Hydrolysis and decarboxylation of these disubstituted compounds afford the corresponding 3-alkylpyrroles. Mass spectral data for some 1-, 2-, and 3-alkylpyrroles are reported.