bluuebunny/crossref_metadata_2025 huggingface dataset:
ORGANIC SULFUR COMPOUNDS: II. CATALYZED SODIUM BOROHYDRIDE REDUCTIONS OF SELECTED α-(o-NITROPHENYLTHIO) ACIDS
Authors: Coutts R. T. , Barton D. L. , Smith Elizabeth M.
Published: May 2006

The products obtained when α-(o-nitrophenylthio) acids are reduced by means of sodium borohydride and palladium–charcoal depend on (a) the reaction temperature, (b) the solvent, (c) the length of time in which the α-(o-nitrophenylthio) acid is in contact with the reducing agent, and (d) the nature of the substituents on the α-(o-nitrophenylthio) acid. By varying these conditions, benzothiazine hydroxamic acids (i.e. substituted 3,4-dihydro-4-hydroxy-3-oxo-2H-1,4-benzothiazines), the corresponding lactams (3,4-dihydro-3-oxo-2H-1,4-benzothiazines), and derivatives of 2-carboxymethylthioazobenzene can be prepared.In two cases, additional products were obtained. When (o-nitrophenylthio)acetic acid was catalytically reduced for 30 min in dioxane, 3,4-dihydro-3-oxo-2H-1,4-benzothiazine-1,1-dioxide (VIc) was an unexpected product, and when α-(4-trifluoromethyl-2-nitrophenylthio)-isobutyric acid was left for a prolonged time in contact with sodium borohydride and palladium–charcoal, a derivative of hydrazobenzene, namely, 2-carboxy(α,α-dimethyl)methylthio-5-trifluoromethylhydrazobenzene (V), was one of the three identified products.
4-HYDROXYQUINALDINES IN THE MANNICH REACTION
Authors: Nabih I. , Nasr M.
Published: May 2006

not available
PREPARATION OF 3,4-METHYLENEDIOXY- AND 3,4-DIMETHOXY-6-AMINOPHENOL
Authors: Orphanos D. G. , Taurins A.
Published: May 2006

not available
THE PREPARATION OF 9-HYDROXYPYRAZOLO[3,4-b]QUINOLINES
Authors: Coutts R. T. , Edwards J. B.
Published: May 2006

4-(2-Nitrobenzylidene)-2-pyrazolin-5-ones (I) were best prepared by heating o-nitrobenzaldehyde and 2-pyrazolin-5-ones in acetic anhydride containing fused sodium acetate (cf. Erlenmeyer azlactone synthesis). Pyrazolones of type I were reductively cyclized with cyclohexene and palladium–charcoal, and gave 3a,4,9,9a-tetrahydro-9-hydroxy-1H-pyrazolo-[3,4-b]quinolines (II) which, as expected, were amphoteric compounds. Of the three other methods of reduction used in this study, two (zinc and acetic acid; sodium borohydride and palladium–charcoal) were capable of producing pyrazoloquinolines, but were less reliable. The other method employed (hydrazine hydrate and palladium–charcoal) caused degradation of the pyrazolone molecule in the two cases examined, and in both, bis(2-aminobenzylidene) hydrazine (V) was the reduction product isolated.
CYCLOADDITIONS: X. KINETICS OF THE THERMAL DECARBONYLATION OF DICYCLOPENTADIENE-1.8-DIONE
Authors: Baldwin John E.
Published: May 2006

The thermal cycloelimination of carbon monoxide from dicyclopentadiene-1,8-dione is a kinetically well-behaved first-order reaction. At 380 °K the activation parameters for the process are ΔH≠ = 34.5 ± 0.8 kcal mole−1 and ΔS≠ = +9.8 ± 2.3 e.u. mole−1. Application of the theoretical proposals of Woodward and Hoffmann indicates that this necessarily disrotatory decarbonylation may be concerted.
ÉTUDES CONFORMATIONNELLES EN SÉRIE CYCLOPENTANIQUE: II. SUR LA STÉRÉOCHIMIE DES ALCOOLS TERTIAIRES DÉRIVÉS DE LA t-BUTYL-3 CYCLOPENTANONE
Authors: Richer Jean-Claude , Bélanger Patrice
Published: May 2006

not available
REACTIONS OF PHTHALIMIDE AND POTASSIUM PHTHALIMIDE WITH SULFUR MONOCHLORIDE
Authors: Kalnins Malda V.
Published: May 2006

not available
THE DEHYDRATION OF AMIDES TO NITRILES WITH LITHIUM ALUMINIUM HYDRIDE
Authors: Humber L. G. , Davis M. A.
Published: May 2006

not available
EQUILIBRIUM CONSTANTS OF ZINC(II) AND COPPER(II) WITH HEMATOPORPHYRIN IX
Authors: Brisbin D. A. , Balahura R. J.
Published: May 2006

Equilibrium constants have been measured for the following displacement reactions between copper(II) and zinc(II) with hematoporphyrin IX.[Formula: see text]Preliminary measurements have also been made for the reactions of Mn(II) and Co(II) with hematoporphyrin IX in glacial acetic acid solutions.
INTERSYSTEM CROSSING OF THE ELECTRONICALLY EXCITED DIDEUTEROETHYLENE MOLECULES FORMED IN BENZENE PHOTOSENSITIZATION
Authors: Terao Terumi , Hirokami Shun-Ichi , Sato Shin , Cvetanović R. J.
Published: May 2006

Experimental evidence is presented for a rapidly occurring intersystem crossing of the electronically excited dideuteroethylene molecules initially formed in the benzene-photosensitized reaction at 2 537 Å and 25 °C to another excited state which is responsible for the internal H-atom scrambling. The mechanism is entirely analogous to that previously postulated for the photoexcited states sensitized by Hg(3P1) atoms but the rate constants for intersystem crossing and molecular decomposition are drastically decreased as a result of the smaller amount of energy available for the excitation.
THE WATER-SOLUBLE POLYSACCHARIDES OF DERMATOPHYTES: VI. GLUCANS FROM TRICHOPHYTON GRANULOSUM, TRICHOPHYTON INTERDIGITALE, MICROSPORUM QUINCKEANUM, TRICHOPHYTON RUBRUM, AND TRICHOPHYTON SCHÖNLEINII
Authors: Bishop C. T. , Perry M. B. , Hulyalkar R. K. , Blank F.
Published: May 2006

Polysaccharides obtained from each of the organisms designated in the title have been resolved into three groups: galactomannans I, galactomannans II, and glucans. The five glucans were homogeneous under conditions of electrophoresis, and had identical electrophoretic mobilities and infrared spectra. Methylation and hydrolysis of the glucans yielded varying amounts of the following: 2,3,4,6-tetra-O-methyl-D-glucose, 2,3,4-tri-O-methyl-D-glucose, 2,4,6-tri-O-methyl-D-glucose, and 2,4-di-O-methyl-D-glucose. The glucans were therefore branched polysaccharides, with branches formed by substitution at the C-3 and C-6 positions of D-glucopyranose units and terminated by D-glucopyranose units. The linear portions of the glucans contained 1 → 6 and 1 → 3 linkages but in varying amounts. These differences and some variation in the degrees of branching constituted the only dissimilarities detectable in the glucans by these structural studies.
THE INTERCONVERSION OF 5-CHLORO- AND 5-HYDROXY-DIPYRRYLMETHENES
Authors: Markovac A. , Kulkarni B. D. , Shaw K. B. , MacDonald S. F.
Published: May 2006

Like the known II, the 5-halo-dipyrrylmethenes IV, X, and XI were obtained conventionally by halogenating the pyrroles I and IX. The 5-free dipyrrylmethene VIII, a new type of intermediate in such halogenations, was obtained from the pyrrole ester VII. The four 5-halo-dipyrrylmethenes were hydrolyzed to the 5-hydroxy derivatives VI and XIII, and these were reconverted into 5-chloro-dipyrrylmethenes.
A ONE-STEP CONVERSION OF CYCLOHEXENE OXIDE INTO cis-1,2-DICHLOROCYCLOHEXANE
Authors: Campbell J. R. , Jones J. K. N. , Wolfe Saul
Published: May 2006

not available
REACTIONS OF ALKOXY RADICALS: I. HYDROGEN ATOM ABSTRACTION FROM SUBSTITUTED TOLUENES
Authors: Kennedy B. R. , Ingold K. U.
Published: May 2006

The relative rates of hydrogen atom abstraction from ten substituted toluenes by t-butoxy radicals in carbon tetrachloride at 40 °C have been measured and the data fitted to the Hammett equation. A much better correlation is obtained with the σ+ constants than with the σ constants of the substituents. In this respect, therefore, the reaction is similar to the majority of hydrogen atom abstraction reactions by radicals of moderate and high electron affinity. That is, the polar properties of the substituents are much more important than their stabilizing effect on the benzyl radical formed in the reaction.The cumyloxy radical has a similar reactivity to the t-butoxy radical. The p-nitrocumyloxy radical appears to be slightly more reactive and also slightly more susceptible to the polar effects of substituents than are t-butoxy or cumyloxy radicals.
THE IONIZATION BEHAVIOR OF AMIDES IN CONCENTRATED SULFURIC ACIDS: III. INDICATOR ACTIVITY COEFFICIENT VARIATION
Authors: Sweeting Linda M. , Yates Keith
Published: May 2006

Activity coefficient data for ten substituted benzamides and two benzamide salts have been obtained from solubility measurements in 0–70% sulfuric acid. The ionic activity coefficients have been referred to a standard ion, the tetraethylammonium ion. The variations of activity coefficient with acid concentration are discussed and compared with available data for anilines and anilinium ions. Estimates have been made of the relative importance of the various terms contributing to the total acidity function for sulfuric acid. Up to 40% acid the order of importance of these terms is [Formula: see text] and in more concentrated acids becomes [Formula: see text].
SOLVOLYSES OF 2-(2,4-DIMETHOXYPHENYL)-1,1-d2-ETHYL AND 2-(3,5-DIMETHOXYPHENYL)-1,1 -d2-ETHYL p-BROMOBENZENESULFONATES; ION-PAIR RETURNS IN SOLVOLYSES OF 2-ARYLETHYL SYSTEMS
Authors: Lee C. C. , Noszkó L.
Published: May 2006

Acetolysis and formolysis of 2-(2,4-dimethoxyphenyl)-1,1-d2-ethyl and 2-(3,5-dimethoxyphenyl)-1,1-d2-ethyl p-bromobenzenesulfonates were allowed to proceed for about two half-lives, and the corresponding acetate and formate products as well as the unsolvolyzed sulfonate esters were recovered and analyzed by nuclear magnetic resonance. In the 2,4-dimethoxy substituted system, both acetolysis and formolysis gave products showing practically equal distributions of the deuterium in the C-1 and C-2 positions of the ethyl chain. For the 3,5-dimethoxy substituted system, deuterium isotope position rearrangements from C-1 to C-2 in the products were found to be 14 and 26%, respectively, for acetolysis and formolysis. These results provide more quantitative verifications of earlier conclusions, based on kinetic data, regarding the extents of involvement of bridged ions as reaction intermediates. The unsolvolyzed sulfonate ester recovered from the acetolysis of either the 2,4- or 3,5-dimethoxy substituted system showed a significant amount of deuterium rearrangement from C-1 to C-2, indicating the occurrence of ion-pair returns. On the other hand, such rearrangements were negligibly small in the sulfonates recovered after partial formolysis. By utilizing data on isotopic rearrangements in the recovered sulfonates obtained from the present work or from the literature, values of kα/kt, the ratio of the total reaction rate to the titrimetric rate, were calculated for a number of 2-arylethyl systems. Implications of the present results on a general mechanism for the solvolyses of 2-arylethyl arenesulfonates are also discussed.
SECONDARY KINETIC ISOTOPE EFFECTS IN THE SOLVOLYSES OF 2-(2,4-DIMETIIOXYPHENYL)-1,1-d2-ETHYL AND 2-(3,5-DIMETHOXYPHENYL)-1,1-d2-ETIIYL p-BROMOBENZENESULFONATES
Authors: Lee C. C. , Noszkó L.
Published: May 2006

The secondary α-deuterium kinetic isotope effects in the acetolyses and formolyses of 2-(2,4-dimethoxyphenyl)-ethyl and 2-(3,5-dimethoxyphenyl)-ethyl p-bromobenzenesulfonates (I-OBs and II-OBs, respectively) and their corresponding 1,1-dideuterio analogues (I-OBs-1-d2 and II-OBs-1-d2) were determined. The observed kH/kD values are compared with similar data from the literature for 2-phenylethyl and 2-p-anisylethyl p-toluenesulfonates (III-OTs and IV-OTs, respectively). In the formolyses of III-OTs, IV-OTs, and I-OBs, which proceed either chiefly or exclusively by way of bridged ions as intermediates, the isotope effects appear to increase slightly with increasing bridged-ion stability. For I-OBs and I-OBs-1-d2, acetolyses gave smaller kH/kD values than formolyses because of deuterium scrambling caused by ion-pair returns during the acetolysis. Acetolyses and formolyses of II-OBs and II-OBs-1-d2 gave lower isotope effects than the corresponding reactions with I-OBs and I-OBs-1-d2. The magnitudes of the observed isotope effects in relation to transition-state structures are discussed.
QUINODIMETHANE CHEMISTRY: THE GENERATION AND TRAPPING OF QUINODIMETHANES FROM SUBSTITUTED AROMATIC HYDROCARBONS WITH HIGH-POTENTIAL QUINONES
Authors: Lown J. W. , Aidoo A. S. K.
Published: May 2006

9,10-Dimethylanthracene and 9,10-dimethyl-9,10-dihydroanthracene react with 2 and 3 moles, respectively, of tetrachloro-l,2-benzoquinone to give the same 1:1 adduct of 9,10-anthraquinodimethane with the quinone, the structure of which was proved by ozonolysis. A lower limit for the rate of adduct formation in 1,2-dichlorobenzene at 80° is 4.22 × 10−2 l mole−1 s−1. 7,12-Dimethylbenzanthraquinodimethane was generated in a similar way and the structure of the 1:1 adduct proved by ozonolysis and by mass spectrometry. The reaction of 9,10-anthraquinodimethane with a p-quinone gave a 1:2 adduct. 9-Methylanthracene reacts with high-potential quinones by hydride abstraction at the methyl group with the formation of an ether.
ORMOSIA ALKALOIDS: IV. STEREOCHEMISTRY OF ORMOJANINE; STRUCTURE AND STEREOCHEMISTRY OF PIPTANTHINE, DASYCARPINE, AND ORMOSININE
Authors: Deslongchamps P. , Valenta Z. , Wilson J. S.
Published: May 2006

By using the known structure and stereochemistry of the alkaloid ormosanine, C20H35N3 (I), as reference, the structure and stereochemistry of the isomeric compounds piptanthine (II), tetrahydro-ormojanine (XIV), isotetrahydro-ormojanine (XIII), and dasycarpine (XX) have been elucidated by isomerization and reduction experiments. Three additional C20H35N3 bases possessing the ormosanine skeleton have been prepared by the reduction of pyridine VII. Thus, of the 15 possible stereoisomers of ormosanine, 7 are now known.The study leads to the stereo-formula XIX for the alkaloid ormojanine, C20H31N3. The alkaloid ormosinine has been found to be a dimer of panamine.Stereochemical aspects of the catalytic and chemical reductions of the double bonds and pyridine rings contained in the described compounds are discussed. A possible biogenetic intermediate is proposed which explains the presence of both antipodal series of Ormosia alkaloids in nature.
ISOTOPE EFFECT STUDIES ON ELIMINATION REACTIONS: V. THE MECHANISM OF THE CARBONYL ELIMINATION REACTION OF 9-FLUORENYL NITRATE WITH ACETATE ION
Authors: Smith P. J. , Bourns A. N.
Published: May 2006

The carbonyl elimination reaction (ECO2) of 9-fluorenyl nitrate with acetate ion in anhydrous ethanol was found to be second order and to give at 30° primary nitrogen-15 and deuterium isotope effects of 1.0091 ± 0.0007 and 4.3 ± 0.2, respectively. The ester showed no deuterium exchange with solvent under the reaction conditions. A change in solvent to 85 volume % ethanol–water increased the nitrogen isotope effect to 1.0131 ± 0.0007 without changing the deuterium effect. These results exclude any form of two-stage carbanion intermediate mechanism, but are in accord with a concerted process.
A STUDY OF THE MANNICH REACTION WITH PROPARGYL ALCOHOL
Authors: Salvador R. L. , Simon D.
Published: May 2006

not available
THE REACTIONS OF ACTIVE NITROGEN WITH ETHYLENE AND DEUTERATED ETHYLENES
Authors: Foster Kenneth D. , Kebarle P. , Dunford H. B.
Published: May 2006

The reaction of active nitrogen with ethylene and deuterated ethylenes has been investigated by use of a mass spectrometer. The rate of disappearance of atomic nitrogen in the presence of ethylene appears to obey the equation[Formula: see text]where kapp is an apparent second order rate constant and [ethylene]0 is the initial concentration of added ethylene. However, exceptions to this equation are found at 0.6 Torr either for short reaction times or for small concentrations of added ethylene, and apparently for short reaction times at 2.6 Torr when a large excess of ethylene is added. Where the above equation is obeyed, kapp = (3 ± 1) × 10−13 cc molecule−1 s−1. The formation of C2D4 in the reaction of active nitrogen with C2D3H is interpreted as further evidence for the importance of hydrogen atom reactions in intermediate steps of the reaction of active nitrogen with ethylene.
SOLVENT DEPENDENCE OF 29Si—19F COUPLING CONSTANT IN SILICON TETRAFLUORIDE. THE IMPORTANCE OF INTERMOLECULAR DISPERSION INTERACTIONS
Authors: Hutton H. M. , Bock E. , Schaefer T.
Published: May 2006

not available
THE CHEMISTRY OF THE INDOLE GRIGNARD REAGENT: I. THE REACTION OF INDOLE MAGNESIUM IODIDE WITH ETHYL CHLOROFORMATE
Authors: Kašpárek S. , Heacock R. A.
Published: May 2006

In contrast to previous reports in the literature, it has been shown that both 1- and 3-carbethoxyindole are obtained from the reaction of indole magnesium iodide with 1 or 2 moles of ethyl chloroformate. The formation of 1-carbethoxyindole was favored at low temperatures (i.e. −10°), whereas maximum yields of 3-carbethoxyindole were obtained at 10°. Significant quantities of 1,3-dicarbethoxyindole are only formed in the presence of 2 equivalents of ethyl chloroformate and when the reaction is carried out at higher temperatures (i.e. 35°).Paper and gas–liquid chromatographic systems have been developed for the qualitative and quantitative analysis of mixtures containing indole, 1-, 2-, and 3-carbethoxyindole, and 1,3-dicarbethoxyindole.
THE ORTON REARRANGEMENT IN APROTIC SOLVENTS: III. THE ACID-CATALYZED CHLORINATION OF ANISOLE BY A SERIES OF 4-SUBSTITUTED N-CHLOROACYLANILIDES
Authors: Scott John M. W. , Martin June G.
Published: May 2006

Anisole has been chlorinated with a sequence of chlorinating agents generated by the reaction of a series of 4-substituted N-chloroacylanilides (4-X-C6H4NClAc (X = Me, H, and CN)) with a series of carboxylic acids (R—COOH (R = CF3, CCl3, CH2Cl, and CH3)). The isomer ratios of the 2- and 4-chloroanisoles produced in these reactions have been measured for each N-chloroacylanilide – carboxylic acid pair, and are found to be dependent on the strength of the catalyzing acid but independent of the structure of the N-chloroacylanilide within the precision of the reported data. These observations are consistent with both the termolecular scheme proposed in part II of this series and the Soper mechanism. However, evidence derived from these and other observations suggests that the termolecular scheme is still the most probable mechanism for the chlorine transfer reaction.
THE SYNTHESES OF 1-CHLORO-1-NITROALKENES
Authors: Carroll F. I. , Kepler J. A.
Published: May 2006

Chlorination of 1-nitroalkenes in acetic acid at 0° in the presence of hydrogen chloride gives the corresponding 1,2-dichloro-1-nitroalkanes in good yields. If the reaction is carried out at higher temperatures, an α-chlorohydroxamoyl chloride, resulting from the reaction of the nitroalkene with hydrogen chloride, is obtained as a side product. Base-catalyzed elimination of hydrogen chloride from the 1,2-dichloro-1-nitroalkenes gave the corresponding 1-chloro-1-nitroalkenes in high yields.
A study of cis-trans isomerism and conformational preferences of thioanilides
Authors: Rae Ian D.
Published: May 2006

In thioanilides, cis-trans isomerism has been clearly differentiated from thioamide – thiolimidic acid tautomerism. The isomer ratio has been related to structural and environmental influences on the thioamide group by means of infrared and proton magnetic resonance spectroscopy. In the thioanilides, the thioamide group does not lie in the ring plane unless constrained to do so by hydrogen bonding between the thioamide proton and a suitable ortho substituent.
A new synthesis of 3-acetamido-3-deoxy-d-glucose
Authors: Williams D. T. , Jones J. K. N.
Published: May 2006

A new synthesis of 3-acetamido-3-deoxy-d-glucose (kanosamine) has been devised, involving the replacement by azide ion, with inversion, of the sulfonate group in 1,2;5,6-di-O-isopropylidene-3-O-p-tolylsulfonyl-d-allofuranose.
Dimerization of an intermediate during the sodium in liquid ammonia reduction of l-thiazolidine-4-carboxylic acid
Authors: Blondeau P. , Berse C. , Gravel D.
Published: May 2006

Reduction with sodium in liquid ammonia of l-thiazolidine-4-carboxylic acid (II) leads, depending on the reaction procedure followed, to N-methyl-l-cysteine (I) or a mixture of N-methyl-l-cysteine (I) (30%) and a dimer (50%), the structure of which is shown to be VI. Contrary to what has been expressed in the literature, the reaction of 1,2-dichloroethane with cysteine (III) at a pH of 8–10 does not lead to compound VI but to compound VIII.
The radiation chemistry of dihydromyrcene
Authors: Brash John L. , Golub Morton A.
Published: May 2006

Dihydromyrcene was irradiated with 1-MeV electrons at room temperature both in the pure state and in benzene solution. The main reactions observed, and their G-values for the pure diisoprene, were loss of unsaturation (~7.8–9.9), cross-linking (or dimerization) (2.4–2.6), evolution of hydrogen (0.81), and trans → cis isomerization (< 0.5). As with squalene, the loss of double bonds in dihydromyrcene occurred only in the cross-linked residue, obtained on distillation of the irradiated isoprenoid. Although the residue (mainly dimer, with some trimer) was considered to be partially cyclized, no cyclization of uncross-linked (monomeric) dihydromyrcene was observed. Dihydromyrcene in 10% benzene solution (by weight) showed trans → cis and cis → trans isomerization with G-values of 0.63 and 1.2, respectively, hydrogen evolution with a G-value of 0.08, and a higher rate of loss of original unsaturation than in the pure state.
Oxygen exchange between chromium(VI) oxyanions and water
Authors: Holyer R. H. , Baldwin H. W.
Published: May 2006

The rate of oxygen exchange between O18 enriched CrO42− HCrO4−, Cr2O72− and solvent water has been measured as a function of pH and total chromium(VI) concentration. The exchange can be explained in terms of the dimerization equilibria

[Formula: see text] and

[Formula: see text] except at high pH, where slow pH-independent exchange is observed. Rate constants for the reactions of the dimerization equilibria have been evaluated from the exchange results, and are in agreement with values obtained by a variety of other methods.
Pyrazolines. VII. Concerning the formation of olefins from the pyrolysis of pyrazolines
Authors: McGreer Donald E. , Wu Weh-Sai
Published: May 2006

The geometrically isomeric cis- and trans-5-3-methyl-4-ethyl-3-carbomethoxy-Δ1-pyrazolines were prepared and their pyrolysis and photolysis studied. The isomeric pyrazolines gave cyclopropane products of mixed stereochemistry, but predominantly with retention of the stereochemistry present in the starting pyrazoline. Each pyrazoline gave stereospecifically a different α,β-unsaturated ester product. This stereospecificity can be related to the structure of the pyrazoline through the requirement that the loss of nitrogen must be from the side of the pyrazoline that is trans to the hydrogen at C-4.
Aromatic substitution. XV. The homolytic methylation of pyridine and 3- and 4-picoline
Authors: Abramovitch R. A. , Kenaschuk K.
Published: May 2006

The ratios of isomers formed in the free-radical methylation of pyridine and 3- and 4-picoline have been determined and the results compared with the corresponding phenylations. The results support the concept that methyl radicals are more nucleophilic than phenyl radicals.
The acid-catalyzed hydrolysis of methyl 2-chloro-2-deoxy-β-D-glucopyranoside
Authors: Buncel E. , Bradley P. R.
Published: May 2006

The kinetics of the hydrolysis of methyl 2-chloro-2-deoxy-β-D-glucopyranoside have been determined in hydrochloric acid solutions over a range of acid concentrations and temperatures. Chloro substitution reduces the rate by a factor of 35 compared with the hydroxy analogue. Application of the Hammett criterion indicates a unimolecular (A-1) mechanism of hydrolysis, as does application of the Bunnett criterion. The entropy of activation, however, is considerably smaller than that observed for the hydrolysis of methyl β-d-glucopyranoside. This is interpreted as being indicative of partial A-2 character.
Relationship between oxygen-17 nuclear magnetic resonance chemical shifts and Π-bonding to oxygen in the dichromate ion
Authors: Kidd R. G.
Published: May 2006

A linear relationship between 17O chemical shift and degree of π-bonding from oxygen to chromium in a number of chromium(VI) compounds is reported. The basis for this relationship is presented in terms of chemical shift theory. The 17O chemical shift values for the two types of oxygen in the Cr2O72− ion are shown to be consistent with an angular rather than a linear Cr—O—Cr arrangement.
Kinetics of the copper-catalyzed hydrogenation of ethylene
Authors: Messervy D. T. , Hayes K. E.
Published: May 2006

The kinetics of the hydrogen–ethylene reaction, catalyzed by unsupported copper, have been studied in the temperature range 0–250 °C. An empirical Rideal–Eley rate equation has been found to fit the data over the whole temperature range. A simplified Twigg mechanism is proposed to account for the experimental observations.
An electron paramagnetic resonance spectroscopic investigation of hydroxyl-radical attack on allyl alcohol
Authors: Smith P. , Wood P. B.
Published: May 2006

Allyl alcohol has been subjected to hydroxyl-radical attack at 25 ± 2 °C within the cavity of an X-band electron paramagnetic resonance (e.p.r.) spectrometer by use of an aqueous flow system in which the hydroxyl radicals were generated by mixing solutions of titanous chloride and hydrogen peroxide containing sulfuric acid. The reaction conditions were varied over a considerable range. At low allyl alcohol concentrations the e.p.r. absorption observed arose chiefly from the two possible addition products CH2(OH)CHCH2OH, I, and ·CH2CH(OH)CH2OH, II, present in roughly equal steady-state molar concentrations; a relatively weak signal from the hydrogen-atom abstraction product CH2:CHCHOH, III, was also observed. As the allyl alcohol concentration was raised, the relative contribution from I and II fell while that from the products of the addition of I and II to allyl alcohol became increasingly evident. These results considerably extend and clarify those previously reported for allyl alcohol by earlier workers using this reaction system.
Relative rates of reaction of olefins with the ground and the first excited electronic states of methylene
Authors: Krzyzanowski S. , Cvetanović R. J.
Published: May 2006

Relative rates of reaction of a number of olefins with the ground state triplet and the first excited electronic state (the lowest singlet) of methylene have been determined at room temperature. The rates depend relatively little on olefin structure. Triplet methylene is somewhat more discriminating and, in particular, reacts considerably more rapidly with 1,3-butadiene than with monoolefins.
Vapor phase radiation chemistry studied by electron spin resonance spectroscopy
Authors: Smith D. R. , Tole J. C.
Published: May 2006

The techniques and some preliminary results of an indirect method of studying vapor phase radiolysis by electron spin resonance (e.s.r.) spectroscopy are reported. After traversing a beam of 40 keV Ar+ ions, a stream of vapor is condensed on a cold finger at 77 °K. Free radicals which are formed by ion bombardment in the vapor phase become trapped in the solid deposit and are detected by e.s.r. Various vapors such as cyclopentane, cyclohexane, benzene, and ethanol have been bombarded at room temperature. The results correlate with conventional radiation chemical data. For example, benzene forms

[Formula: see text] (and probably

[Formula: see text]) radicals. These may be the intermediates which lead to polymer formation when benzene vapor is irradiated. The potential value of the experiment to vapor phase radiation chemistry is discussed.
Spectroscopic evidence for hydrated electrons in the electrolysis of water
Authors: Walker David C.
Published: May 2006

This paper describes the observation and measurement of a strong absorption at 6 330 Å by a species produced very close to a polished silver cathode in the electrolysis of aqueous solutions. The species is likely to be the hydrated electron, thus corroborating some earlier chemical evidence. The technique involves directing a laser beam along a long, curved, polished, silver electrode surface and measuring very small changes in light transmission by modulating the electrolytic current at a frequency to which the detector's amplifier has been tuned.
High temperature solution calorimetry. Part II. Thermodynamic investigation of the systems: AgCl–KCl, AgCl–RbCl, AgCl–CsCl
Authors: Baboian R. , Flengas S. N.
Published: May 2006

The thermal properties of the binary systems AgCl–KCl, AgCl–RbCl, and AgCl–CsCl have been investigated over the entire composition range and in the temperature range 660 to 860 °C. From the combined results of the calorimetric investigation and the measured phase diagrams of the binary systems, activities and other partial molar properties have been calculated.
Electron spin resonance observations on trapped electrons and free radicals formed in olefins at 77 °K by γ-irradiation
Authors: Smith D. R. , Okenka F. , Pieroni J. J.
Published: May 2006

Electron spin resonance (e.s.r.) methods have been used to search for the γ-ray-induced formation of trapped electrons and free radicals in 13 straight-chain and branched-chain terminal olefins at 77 °K. When e.s.r. spectra were observed they were used to identify the species present. Changes induced by subsequent exposure to visible and ultraviolet (u.v.) light were investigated. Trapped electrons were observed in three olefins that exist as glasses at 77 °K, hexene-1, hexene-2, and 2-methylbutene-1, but were not detected in two other glassy olefins, possibly because of rapid annealing. No trapped electrons were found in polycrystalline olefins at 77 °K. The possibility that CO2− ions have been misinterpreted as trapped electrons in these and other systems is discussed and eliminated. The formation and behavior of free radicals and trapped electrons in irradiated 2-methylbutene-1 are analogous to those previously reported for 2-methylpentene-1 under similar conditions. These observations support the hypothesis that in these two systems ions produced initially isomerize rapidly, leading to the formation of the free radicals detected by e.s.r. The results of a subsidiary experiment suggest that hydrogen abstraction from the matrix is induced by u.v. photolysis of the radicals present in 2-methylpentene-1.
Reaction of active nitrogen with ammonia
Authors: Back R. A. , Salahub D. R.
Published: May 2006

The reaction of14N-active nitrogen with15N-ammonia produces only N2and H2. The nitrogen is exclusively14N15N. It is concluded that the primary process

[Formula: see text](where N2* is probably in the A3Σu+state, or a vibrationally excited X1Σg+state) is followed by the secondary reactions

[Formula: see text]

[Formula: see text]which consume nitrogen atoms, in disagreement with earlier conclusions about the ammonia reaction.
Photooxidation of acetone vapor
Authors: Hoare D. E. , Whytock D. A.
Published: May 2006

The photochemical reaction between acetone and oxygen has been studied at temperatures from 100 to 250 °C at several oxygen pressures with light of 3 130 Å. A study of the quantum yields of all the major products has shown the necessity of introducing the reaction

[Formula: see text]

[Formula: see text]to the generally accepted mechanism, with a rate constant about 80 times that of the reaction

[Formula: see text]at 100 °C. Both this reaction and the reaction of acetyl radicals with oxygen appear to have low or negative activation energies, consistent with a rate-determining process involving combination of the radical with oxygen. The reaction of acetonyl radicals with oxygen to give carbon monoxide is not important at temperatures below 150 °C, but it becomes the most important reaction at temperatures above 250 °C.
An acidity function in ethanol – sulfuric acid based on the protonation of diphenylamines
Authors: Dolman Douglas , Stewart Ross
Published: May 2006

A Hammett H0 acidity function based on the protonation of 17 diphenylamines in 20 volume % ethanol – aqueous sulfuric acid has been established. The H0 value for the most acidic solution studied (11.2 M sulfuric acid) is −6.97. This acidity function differs from that based on the protonation of azobenzenes in the same solvent system; the latter diverges to more negative H0 values as the sulfuric acid concentration increases.The

[Formula: see text] values for the protonation of the diphenylamines vary from +1.36 for 4-methoxy-diphenylamine to − 6.21 for 4,4′-dinitrodiphenylamine. A plot of

[Formula: see text] versus the Hammett σ constants for five monosubstituted diphenylamines yields a ρ value of +3.36. The

[Formula: see text] values for 4-methoxy-, 4-methyl-, 4-methylsulfonyl-, and 4-nitro-diphenylamine are all less (more negative) than expected from the Hammett substituent constants. The substituent effects on the basicities of aniline and diphenylamine are the same.The basicities of several nitro-substituted diphenylamines appear to vary regularly, and do not reflect the presence of a strong interaction between the nitro group and sulfuric acid.
Acetylenic esters. II. Further addition reactions with sulfur- and nitrogen-containing compounds
Authors: Lown J. W. , Ma J. C. N.
Published: May 2006

Substituted thiosemicarbazides react with dimethyl acetylenedicarboxylate to give 3-amino-2,3-dihydrothiazin-4-ones. Confirmation of the structures is provided by catalytic hydrogenation and by characteristic mass spectral fragmentations. 4-Substituted thiosemicarbazides react with methyl propiolate in the same way as monosubstituted hydrazines and hydrazides to give hydrazones, whereas 1-substituted thiosemicarbazides undergo smooth removal of the sulfur with the production of an equal mixture of cis–trans and cis–cis dimethyl-β-thiodiacrylic esters. Bicyclic heterocyclic structures are formed by reaction of dimethyl acetylenedicarboxylate with imidazolidone thione and with 5,5-dimethyl-2-thiohydantoin. Substituted guanidines react with dimethyl acetylenedicarboxylate in an analogous fashion, yielding substituted 2,3-dihydrodiazinones. The high-resolution mass spectra of the latter show many similarities to the spectra of the sulfur analogues. Thioamides, despite previous claims to the contrary, react with dimethyl acetylenedicarboxylate to give thioethers of fumarate ester or 1,3-thiazin-4-ones. In contrast, thioamides react with methyl propiolate to give an equal mixture of cis–trans and cis–cis dimethyl-β-thiodiacrylic esters.
Velocity of sound in liquid CF4
Authors: Aziz R. A. , Lim C. C. , Bowman D. H.
Published: May 2006

The velocity of sound in liquid CF4has been measured in the temperature range from its triple point to its normal boiling point. Measurements have been made with an ultrasonic interferometer, consisting of barium titanate ceramic in tubular form, to an accuracy of 0.4% or better. The adiabatic compressibility has also been calculated for the corresponding temperature range using available density data. No other velocity of sound or compressibility data for CF4are available for comparison. Comparisons with other liquids by the method of corresponding states show similarity between CF4and CCl4, but not between CF4and methane or argon.
Nuclear magnetic resonance spectra of some fluorinated organotin compounds
Authors: Clark H. C. , Cyr N. , Tsai J. H.
Published: May 2006

The unusual features of the proton and 19F nuclear magnetic resonance spectra of (CH3)3SnCF2CFHCF3, arising from the asymmetry about the β-carbon atom, are discussed in terms of the molecular stereochemistry. Data for (CH3)3SnCF2CF(CF3)Sn(CH3)3, (CH3)3SnCF2CF2H, and (CH3)3SnCF2(CF2)2CF2H are also presented.
Concerning the role of the reaction field in the proton shielding of molecules in solution
Authors: Kotowycz G. , Schaefer T.
Published: May 2006

It is shown that the strong curvature in some plots of proton chemical shift σ versus the Onsager reaction field E can be removed by plotting the shifts of the solute molecule versus the square root of the dielectric constant of the medium. The resulting values of k in the equation σ = −kE cos θ are fairly consistent and reasonable in magnitude.
Proton conductance of copper sulfate pentahydrate crystals
Authors: Williams D. F. , Sykes B. , Schneider W. G.
Published: May 2006

It has been demonstrated that protons are injected into single crystals of copper sulfate pentahydrate by using saturated aqueous solutions of copper sulfate as electrodes. The resulting proton current is space-charge limited and follows Child's law, from which a proton mobility of 10−5 cm2 V−1 s−1 was deduced. The injected proton current was verified by tracer experiments with tritium.
Solvents effects on the proton chemical shift and H—H, H—F coupling constants in 1-chloro-1-fluoroethylene. Reaction field and dispersion interactions
Authors: Hutton H. M. , Schaefer T.
Published: May 2006

The proton chemical shift and the geminal proton–proton and cis proton–fluorine coupling constants in 1-chloro-1-fluoroethylene depend primarily on the dielectric constant of the medium, although this dependence is not given by the Onsager reaction field model. A roughly linear relationship is found with the square root of the dielectric constant. The proton coupling constant decreases algebraically while the cis proton–fluorine coupling constant increases as the dielectric constant of the medium increases. The trans proton–fluorine coupling depends on dispersion interactions with the solvent molecules and increases as these interactions increase. The geminal coupling constant varies between − 3.8 and − 4.8 c.p.s., the cis coupling between 7.6 and 12.3 c.p.s., and the trans coupling between 36.9 and 38.6 c.p.s.
Some complexes of Fe(II) with thiourea ligands
Authors: Bailey R. A. , Peterson Terry Roy
Published: May 2006

Fe(thiourea)2(SCN)2, Fe(thiourea)4Cl2, and FeL2Cl2 (where L = methylthiourea, 1,3-dimethylthiourea, and 1,3-diethylthiourea) have been prepared and characterized. Magnetic moments and ligand field spectra indicate that all are octahedral. Infrared spectra show that the thiourea and methylthiourea ligands coordinate through the sulfur atom; the other two ligands are probably sulfur bonded also. The thiocyanate ion is coordinated through the nitrogen.
The biosynthesis of sedamine
Authors: Gupta R. N. , Spenser Ian D.
Published: May 2006

The biosynthesis of sedamine (IX) was studied in excised shoots of Sedum acre L. Phenyl-alanine serves as the precursor of the C6 – C2side chain. The piperidine nucleus is derived from lysine, which is incorporated by way of a nonsymmetrical intermediate. These findings are consistent with Robinson's classical biogenetic hypothesis. They are incompatible with a polyacyl origin of the sedamine skeleton.
Chemistry of phosphorus fluorides. Part II. Secondary alkylamino derivatives of phosphoryl fluoride
Authors: Cavell R. G.
Published: May 2006

Phosphoryl fluoride reacts with dimethylamine in an equimolar ratio to yield volatile dimethylaminophosphoryldifluoride. The residual solid is a mixture of dimethylammonium hexafluorophosphate and dimethylammonium difluorophosphate salts rather than the simple fluoride salt. Dimethylamine reacts slowly with dimethylaminophosphoryldifluoride to yield bis(dimethylamino)phosphorylfluoride and the same complex fluorophosphate anions in the solid products. Physical data are reported on the alkylamino phosphoryl fluorides. The reaction of the difluorophosphoryl compound with hydrogen halides has been studied.
Preparation and infrared spectra of some ammine complexes of ruthenium(II) and ruthenium(III)
Authors: Allen A. D. , Senoff C. V.
Published: May 2006

The infrared spectra of the complexes [Ru(NH3)6]X2 and [Ru(NH3)6]X3, where X = Cl−, Br−, I−, BF4− and [Ru(NH3)5X]X2, where X = Cl−, Br− and I−, have been measured in the solid state between 4 000 – 250 cm−1. Assignments have been made for the observed absorption bands. The metal–nitrogen stretching vibrations were observed between 485–424 cm−1 for the ruthenium(III) complexes but were not observed for the ruthenium(II) complexes in this region.
Secondary reactions in the γ-radiolysis of hydrocarbons with electron scavengers
Authors: Sagert N. H. , Blair A. S.
Published: May 2006

Secondary reactions in the liquid phase radiolysis of cyclohexane in the presence of N2O and SF6 have been examined by determining the yields of liquid products. When we added up to 0.3 M N2O, the hydrogen yield was reduced from its initial yield of 5.5 G units to 2.5 G units. The nitrogen yields were about twice the decrease in hydrogen yields. Bicyclohexyl and cyclohexene yields increased from their initial values to 2.27 and 3.50 G units respectively. When we added up to 0.12 M SF6, all the yields were decreased to about one half of their initial value.These results may be interpreted in terms of Dyne's general mechanism for the radiolysis of hydrocarbons if two cyclohexyl radicals are produced for every electron scavenged by N2O, but if none are produced for electrons scavenged by SF6. It is suggested that the total electron yield in pure cyclohexane is about 4.1 G units, of which only 3.0 G units produce hydrogen. The other 2.5 G units of hydrogen from the radiolysis of pure cyclohexane are presumed to arise from direct excitation.
Studies on metal hydroxy compounds. III. Thermal analyses of cadmium derivatives Cd(OH)2, CdOHCl, and CdOHF
Authors: Srivastava O. K. , Secco E. A.
Published: May 2006

Thermogravimetric and differential thermal analyses of Cd(OH)2, CdOHCl, and CdOHF are reported and discussed. The results show that the presence of a halogen substituent contributes to greater thermal stability of the hydroxy compound. The thermal stability increases in the order Cd(OH)2 < CdOHF ≤ CdOHCl, which is in contrast with the order of the zinc derivatives.The expected increase in the stability of the cadmium hydroxy compounds relative to the zinc hydroxy compounds was observed except for CdOHF. The exception of CdOHF is ascribed to its departure from the expected hexagonal structure and its existence in the orthorhombic form.The cadmium hydroxy compounds decompose via dehydration in the initial step, followed by hydrolysis and (or) volatilization of the cadmium halide to yield an ultimate residue of cadmium oxide.
Use of ionic bombardment to increase the conductivity of metallized thin plastic films for making source mounts
Authors: Roy J. C. , Turcotte J.
Published: May 2006

A study was made of the conductivity of thin flexible collodion films metallized either with gold (99.95%) or with gold – 18% palladium alloy and the results obtained were compared with the conductivity of VYNS (a polyvinylchloride–acetate copolymer) films coated with the same metals. For both types of films the conductivity is better with the alloy, especially for VYNS. VYNS films coated with gold or the alloy show better conductivity than collodion coated with either metal. However, ionic bombardment of the collodion films prior to metal coating considerably improves their conductivity, especially with the Au – 8% Pd alloy. For this' alloy the conductivity goes up by a factor of 100 to 1 000 000, and then becomes better than that obtained with VYNS. Although ionic bombardment had a less pronounced effect on the VYNS, an improvement in conductivity was still observed.On a fait une étude comparative de la conductivité de films minces de collodion et de VYNS métallisés soit avec de l'or, soit avec un alliage or – 18% palladium, en couches variant de 2 à 30 μg/cm2. Pour les deux types de films, la conductivité s'est révélée meilleure avec l'alliage; de plus le VYNS devient plus facilement conducteur que le collodion. Toutefois, les films de collodion soumis à un bombardement ionique avant leur métallisation sont beaucoup plus faciles à rendre conducteurs et leur conductivité devient même supérieure à celle obtenue avec les films de VYNS métallisés par l'alliage. Quoique le bombardement ionique ait un effet moins prononcé sur la conductivité subséquente des films de VYNS, elle est tout de même améliorée de façon appréciable. On décrit également des méthodes simples et rapides pour déterminer l'épaisseur des films de collodion et des couches métalliques déposées sur les films.
Ozonolysis of unsaturated fatty acids. II. Esterification of the total products from the oxidative decomposition of ozonides with 2,2-dimethoxypropane
Authors: Castell John D. , Ackman R. G.
Published: May 2006

The total acidic products from the performic acid oxidation of the ozonide of methyl oleate formed in methanol may be esterified directly in a few hours with 2,2-dimethoxypropane. The ester concentrations are adequate for the determination of the positional isomers of monoethylenic fatty acids directly from the reaction mixture, using a hydrogen flame ionization gas–liquid chromatography detector. Dimethyl sulfoxide was not required to prevent the breakdown of 2,2-dimethoxypropane under the conditions employed.
2-(4-Piperidyl)ethanal and 3-(4-piperidyl)propanal
Authors: Meyer Walter L. , Olsen Ronald G.
Published: May 2006

The title aminoaldehydes were synthesized by N-acetylation of the corresponding aminoalcohols, Kornblum oxidation to amidoaldehydes, formation of the dimethyl acetals, alkaline amide hydrolysis, and finally acidic acetal hydrolysis. Infrared, ultraviolet, and nuclear magnetic resonance spectral examination indicates that, in solution, the aminoaldehyde hydrochlorides exist in equilibrium with gem-diols or hemiacetals, depending upon the solvent, but that the free bases are reversibly converted into dimeric enamines, to which structures are tentatively assigned. No evidence could be obtained for the presence of monomeric bicyclic carbinolamine tautomers of either the free amines or their salts.
A simplified preparation of fully deuterated, high molecular weight hydrocarbons
Authors: Atkinson J. G. , Luke M. O. , Stuart R. S.
Published: May 2006

A novel system for the individual preparation of fully deuterated hydrocarbons with 10 to 36 carbon atoms is described. The system permits the use of unsaturated and saturated, cyclic and acyclic starting materials and results in the perdeuterated, saturated equivalent of the starting material. Exchange occurs between hydrocarbon liquid and deuterium gas over carbon-supported, fixed-bed catalysts of Rh, Pt, and Pd at 190–200 °C and results in perdeuterated products of high isotopic and chemical purity. No cracking or structural isomerization occurs under the conditions used, but epimerization of asymmetric carbon atoms does occur. Yields of 35–75% are obtained, the chief losses being due to volatilization and sample withdrawal. The deuterated hydrocarbons prepared by liquid-phase exchange include n-decane-d22, n-dodecane-d26, n-hexadecane-d34, n-octadecane-d38, n-tetracosane-d50, n-octacosane-d58, n-hexatriacontane-d74, pristane-d40, squalane-d62, cyclododecane-d24, 1,2-dicyclohexylethane-d26, and decalin-d18.
Studies of the acylarylnitrosamine reaction. I. The use of nitrosylsulfuric acid in the preparation of unsymmetrical biaryls
Authors: Ahmad Yusuf , Qureshi M. Ikram , Baig M. Ibrahim
Published: May 2006

Nitrosylsulfuric acid, which is very easy to prepare in a pure state and is quite stable at room temperature, has been found to be a very suitable reagent for the nitrosation of acylarylamines. The nitroso derivatives can be isolated easily, and on decomposition in benzene have yielded unsymmetrical biaryls in improved yields. Some of the nitrosations that could not be achieved earlier have now been accomplished successfully by this method.
A novel pentosylmannan arising from the yeast Trichosporon cutaneum
Authors: Gorin P. A. J. , Spencer J. F. T.
Published: May 2006

A polysaccharide containing d-mannose, d-xylose, and l-arabinose was formed exocellularly by Trichosporon cutaneum and isolated via the insoluble copper complex formed with Fehling's solution. A Smith degradation gave an α-(1 → 3)-linked mannan, which represents the backbone of the polysaccharide. Some of the (1 → 3)-linked mannose residues are substituted with d-xylopyranosyl, d-mannopyranosyl, and 4-O-α-l-arabinopyranosyl-d-xylopyranosyl units, forming a branched structure. Radioactive tracer experiments show that d-xylose and l-arabinose units arise from glucose via a C-6 decarboxylation mechanism.
Spectra of some d6 and d8 ions in fused LiCl–KCl at 450 °C
Authors: Dickinson J. R. , Johnson K. E.
Published: May 2006

The spectra of PdCl2, K2PtCl4, K3RhCl6, and K3IrCl6 in fused LiCl–KCl eutectic at 450 °C are reported. The rhodium(III) and iridium(III) species are shown to exist as MCl63− octahedral complexes with lower values of Δ and higher values of β than in aqueous solution. The palladium system is believed to contain the essentially octahedral PdCl64− complex which has a small tetragonal distortion, whereas for the platinum(II) species a purely tetragonal classification is more appropriate.