bluuebunny/crossref_metadata_2025 huggingface dataset:
Decomposition of aqueous dithionite. Part II. A reaction mechanism for the decomposition of aqueous sodium dithionite
Authors: Wayman M. , Lem W. J.
Published: May 2006

The decomposition of dilute aqueous sodium dithionite has been studied in unbuffered solutions by means of continuous polarography, accompanied by recorded pH values. The decomposition–time curve began with a slow "induction" period followed by an S-shaped rapid phase. The pH values decreased slightly during the induction period and increased considerably during the rapid phase. The addition of a solution of fresh decomposition products eliminated the induction phase. The addition of sulfide also eliminated the induction period and catalyzed the reaction. The accepted stoichiometry (2) of the reaction was confirmed. The following sequence of reactions is proposed[Formula: see text][Formula: see text]In the presence of H2S and possibly S formed in side reactions which consume H+, reaction [5] is catalyzed and may be represented as[Formula: see text]and[Formula: see text]The rate equation is represented as[Formula: see text]Reaction [4] is rate limiting during the induction period and reaction [5] (catalyzed), during the rapid phase of decomposition.
A new route to 5- and 6-membered ring sultones
Authors: Durst T. , Tin K.-C.
Published: May 2006

Reaction of 1,2- or 1,3-alkanedisulfonate esters with one equivalent of n-butyllithium in tetrahydrofuran at −78 to 10° affords 5- and 6-membered ring sultones. Similar treatment of alkanesulfonate esters of 1,2-halohydrins gives 5-membered ring sultones. 1,2-Diols and 1,2-halohydrins of known stereochemistry were converted into 5-membered ring sultones in which the stereochemistry at 2 of the 3 ring carbon atoms is uniquely defined. Extension of these reactions to the formation of 7- and 8-membered ring sultones was not successful and products derived from an initial intermolecular reaction were obtained.
Nucleotide syntheses using O2,2′-anhydrouridine
Authors: Ogilvie K. K. , Iwacha D.
Published: May 2006

The synthesis of a nucleotide derivative (3) which can lead directly to O2,2′-anhydro- and arabino- analogues of 1-β-D-ribofuranosyluracil nucleotides is described.
Magnetic interactions in the Mn(II)/cyanide system
Authors: Rotlevi. E. , Eaton D. R.
Published: May 2006

A well-resolved electron spin resonance spectrum has been observed from frozen aqueous, methanol/water mixtures, and acetonitrile/water mixtures of potassium manganocyanide. Hyperfine splitting from at least two manganese atoms is present. The sharpness of the lines indicates that a rate process capable of averaging the anisotropic dipole–dipole interactions is operative. These results are discussed in terms of the known chemical and magnetic properties of Mn(II)/cyanide systems. It is suggested that an exchange process involving low-spin and high-spin manganese ions in the same molecule occurs.
Raman, infrared, and proton magnetic resonance investigation of solutions of zinc nitrate in anhydrous methanol
Authors: Al-Baldawi S. A. , Brooker M. H. , Gough T. E. , Irish D. E.
Published: May 2006

Raman, infrared, and proton magnetic resonance spectra of solutions of zinc nitrate in anhydrous methanol are reported. It is concluded that above −30 °C the zinc and nitrate ions can form contact ion-pairs, but that below −30 °C association is limited to the formation of solvent-separated ion-pairs. The apparent solvation number of zinc, as determined by area measurements on the proton magnetic resonance spectra, decreases with increasing solute concentration, and an interpretation of this effect is given.
Viscosity of associated liquids
Authors: Makhija R. C. , Stairs R. A.
Published: May 2006

Viscosity data for ammonia, methylamine, and 1,2-diaminopropane have been obtained in the temperature ranges −65 to −35, −65 to −10, and −35 to +50 °C, respectively, using an Ubbelohde viscometer. The results were compared with existing data, and all the data were fitted to the Fulcher (Tammann–Hesse) equation by the method of least squares. The significance of the values of T0 in this equation for these and other associated liquids was considered.
Synthesis of the substituted and crosslinked glucoses corresponding to the structural units in a cotton cellulose modified with N-methylbis(2-chloroethyl)amine
Authors: Roberts E. J. , Rowland S. P.
Published: May 2006

The syntheses of simple substituted glucoses (i.e., 2-O-, 3-O-, and 6-O-[(N-methyl-N-2-hydroxyethylamino)ethyl]-D-glucopyranoses) and simple crosslinked glucoses (i.e., N-methylaminobis[O-(N-2-ethyl)-D-glucopyranoses]) with glucose linkages at 2,2′-O-, 3,3′-O-, 6,6′-O-, 2,6′-O-, and 3,6′-O-positions are described. These result from the reactions of "blocked" glucoses with N-methylbis(2-chloroethyl)amine. The new derivatives were characterized by gas–liquid chromatography and electrophoresis. Cotton cellulose modified with N-methylbis(2-chloroethyl)amine to incorporate 0.034 mole of reagent per D-glucopyranosyl unit was hydrolyzed to glucose and substituted glucoses; the substituted glucoses were identified by chromatographic and electrophoretic comparisons with the foregoing authentic glucose derivatives. The relative distribution of (N-methyl-Nhydroxyethylamino)ethyl groups among the 2-O-, 3-O-, and 6-O-positions was 2.30:0.28:1.00. The distribution of crosslinkages among the 2,2′-O-, 2,6′-O-, and 6,6′-O-positions was 2.10:3.72:1.00; these are the only crosslinked derivatives found. The monofunctionally substituted fraction (having a single reagent unit in the substituent group) accounted for 42.6% of the nitrogen; the crosslinked fraction (having a single reagent unit in the crosslink) accounted for 25.8%; complex products accounted for the remainder of the nitrogen of the crosslinked cotton.
Modification of Pascal's triangle for calculating size distributions in polymers
Authors: Whiteway S. G.
Published: May 2006

Pascal's triangle, which is well known to yield all solutions to the factorial part of the Bernoulli binomial probability function, is modified to yield the correct factorial term in expressions for the molecular size distribution in polymers. This approach provides an alternative concept of the meaning of these factorial numbers.
Acetone-sensitized photodimenzation of 3-carene-2,5-dione
Authors: Still Ian W. J. , Macdonald C. J. , Oh (Mrs.) Y.-N.
Published: May 2006

Ultraviolet irradiation of 3-carene-2,5-dione 1 in acetone has been found to yield three cyclobutanetype photodimers. A detailed spectroscopic study of these compounds has shown that the two most abundant dimers possess the head-to-head orientation. The head-to-head dimers have been shown to possess the anti-anti-anti and syn-anti-syn structures 10 and 8 respectively, while the minor, head-to-tail product has one of the corresponding structures 9 or 11. In all three cases, the cyclobutane and cyclohexane rings are cis-fused. Nuclear Overhauser effects enable structures 8 and 10 to be specifically assigned to dimer B and dimer A, respectively.
Carcinogenicity of lactones. IV. Alkylation of analogues of DNA guanine groups such as imidazole, N-methylimidazole, and guanosine by α, β-unsaturated acids
Authors: Jones J. Bryan , Young John M.
Published: May 2006

Studies on the reactions of carcinogenic γ-lactones and related compounds with analogues of guanine DNA residues indicate that the lactones themselves will not effect permanent alkylation of the guanine N-7 position since the Michael addition reactions involved would be readily reversible. In contrast, the α,β-unsaturated acids resulting from hydrolysis of such lactones are effective guanine N-7 alkylating agents owing to zwitterionic stabilization of the corresponding Michael addition products.
Spectrofluorometric studies. VIII. The effect of CO2 and CHCl3 on the photochemistry of monofluorobenzene
Authors: MacBeath M. E. , Unger I.
Published: May 2006

The sensitized emission of biacetyl technique was used to study the effect of CHCl3 and CO2 on the triplet quantum yields of both benzene and monofluorobenzene.The monofluorobenzene was studied at λ excitation (λex) of 2470, 2590, and 2670 Å. At 2470 Å, the triplet yield increased by over 40% with both added gases; at λex 2590 Å, by around 30%; and at λex 2670 Å, about 20%. CHCl3 is slightly more effective than CO2 in enhancing the biacetyl phosphorescent yield. The quantum yield of fluorescence was unchanged with these added gases. Using a slightly improved technique, the comparison irradiation of a benzene–biacetyl mixture at λex 2540 Å with added CHCl3 was repeated. The results confirmed that the biacetyl phosphorescent yield decreased with increasing pressures of CHCl3, but suggest that the effect is not as great as previously reported. At the same wavelength, the triplet yield is unaffected by the addition of CO2. The quantum yield of fluorescence of benzene is virtually unaffected by the added gases. The data suggest that in the monofluorobenzene case the CO2 and CHCl3 are quenching vibrationally excited triplet fluorobenzene molecules.
The Hantzsch pyrrole synthesis
Authors: Roomi M. W. , MacDonald S. F.
Published: May 2006

Ethyl esters of 2-alkyl- and 2,4-dialkylpyrrole-3-carboxylic acids are obtained generally by extensions of the Hantzsch synthesis, benzyl and t-butyl esters when the 2-alkyl group is methyl. Hemopyrrole is obtained from butanal and ethyl acetoacetate in three steps. Pyrroles bearing higher alkyl groups or carbobenzoxy groups are reductively alkylated like the corresponding methylpyrroles and carbethoxy derivatives; t-butyl esters do not survive.
The silver–indium system: thermal analysis, photomicrography, electron microprobe, and X-ray powder diffraction results
Authors: Campbell A. N. , Wagemann R. , Ferguson R. B.
Published: May 2006

In the system Ag–In, the isothermal phase transformation at 281 °C previously assumed by Weibke and Eggers has been found not to exist. Metastability of the γ phase and of the indium phase is persistent at room temperature. The boundaries of the intermediate phases have been redetermined. At room temperature, the equilibrium γ phase (hexagonal) exists between 71.0 and 70.3% silver. At 325 °C and higher temperatures, the γ-phase region extends to higher indium concentrations than those given by Weibke and Eggers. The order–disorder transformation of the γ phase, postulated by Hellner, does not appear to exist. The liquidus is found to lie approximately 8 °C higher than that determined by Weibke and Eggers.At room temperature, the ε phase exists between 67.5 and 65.0% silver. At these compositions, the cubic cell edges of the ε phase are a = 9.878 ± 0.004 and 9.887 ± 0.004 Å, respectively. The γ/(γ + ε) phase boundary has been redetermined and extended.A new α′ phase is claimed to exist at approximately 73.8 wt. % silver. It is formed by a peritectoid phase reaction at 187°. In the α′ phase the silver atoms occupy the face-centered positions and the indium atoms, the corner positions of the cubic lattice. The intensities of diffraction lines were calculated using such a model and were found to be in reasonable agreement with the observed intensities of the α′ phase. The cell edge of the α′ phase is 4.144 + 0.004 Å, at room temperature, and this is identical, within experimental error, with that of the α phase.A new phase diagram for the Ag–In system has been constructed.
Réactions photochimiques de la caféine avec les éthers
Authors: Jerumanis S. , Martel A.
Published: May 2006

The photoreaction of caffeine with dioxane, tetrahydrofuran, tetrahydropyran, anisole, and ethyl ether has been studied. Ultraviolet irradiation of aqueous solutions of caffeine and cyclic ethers in the presence of benzophenone or acetophenone using a pyrex filter yields substitution products. Substitution occurs at the 8-position of caffeine. The photoreaction of caffeine with ethyl ether gives 8-(1-ethoxyethyl)-caffeine and 8-ethylcaffeine while in the presence of anisole caffeine has been found to be completely inert. The structures were determined by infrared, nuclear magnetic resonance, and mass spectrometry.
Vapor absorption spectra of benzoxazole, benzimidazole, and benzothiazole near 2850 Å
Authors: Gordon R. D. , Yang R. F.
Published: May 2006

Sharp vapor absorption spectra, with origins at the frequencies listed, have been observed for benzoxazole (36 493 cm−1), benzimidazole (36 023 cm−1), and benzothiazole (34 327 cm−1). In each case the origin is the strongest band, and excited state fundamentals of approximately 700, 950, and 1225 cm−1 are prominent. The vibrational structure is similar to that of related heterocyclic compounds and some substituted benzenes. There is no evidence of a (π*–n) transition.
Studies on the decomposition of tetra-alkylammonium salts in solution. Part III: Interpretation of Hammett correlations
Authors: Ko E. C. F. , Leffek K. T.
Published: May 2006

Hammett free energy correlations are reported for the decomposition reactions of tetra-alkylammonium halides in chloroform and acetone solution. All the salts contained a substituted benzyl group attached to the nitrogen atom and decomposed to yield a benzyl iodide and dimethylaniline as the only products.The curved Hammett plots for para-substituted benzyl compounds are compared to the linear plot found previously for a series of salts each containing a para-substituted phenyl group, and it is concluded that curved Hammett plots cannot be used as evidence for a change of mechanism, unless direct conjugative effects between substituent and reaction site are absent.
Benzodiazocines. I. Synthesis of hexahydro-1,4-benzodiazocin-2,5-dione
Authors: Muchowski J. M.
Published: May 2006

A three step synthesis of the title compound from isatin is described.
Infrared studies of water in crystalline hydrates: NaClO4•H2O, LiClO4•3H2O, and Ba(ClO4)2•3H2O
Authors: Brink George , Falk Michael
Published: May 2006

Infrared spectra of undeuterated and partially deuterated NaclO4•H2O, LiClO4•3H2O, and Ba(ClO4)2•3H2O were examined. Crystallographic data point to a weak hydrogen bond between water molecules and the perchlorate ions in LiClO•3H2O. This is confirmed by the high HDO stretching frequencies for this compound. The nearly identical HDO stretching frequencies in LiClO4•3H2O, NaClO4•H2O, Ba(ClO4)2•3H2O, and in aqueous solutions of these salts show that similar weak hydrogen bonds occur in all three hydrates and in solution. The hydrogen bond energy is of the order of 2 kcal/mole. In all three compounds the water molecules are symmetric at room temperature. At −165° the water molecules become highly distorted in the sodium compound, slightly distorted in the barium compound, and remain undistorted in the lithium compound. Very narrow OD stretching bands are observed, showing that the hydrogen atom positions are ordered in all three hydrates.
Configurational and conformational influences on the carbon-13 chemical shifts of some carbohydrates
Authors: Perlin A. S. , Casu B. , Koch H. J.
Published: May 2006

Carbon-13 chemical shifts for sugars and methyl glycosides are reported. The following general effects have been observed: (a) a comparison of chemical shifts with expected electron densities suggests that 13C-2 and -4 experience relatively stronger shielding than do 13C-1, -3, and -5, possibly because they oppose the ring O; (b) inversion of an equatorial O to axial O is associated with increased shielding of the 13C nucleus to which it is bonded, of adjacent 13C nuclei, and of those in the β-position (i.e., having an opposing axial H or O); (c) removal of a gauche O,O interaction is associated with 13C deshielding. It appears that since these same steric relationships affect stability, the overall shielding states of 13C nuclei of the different isomers reflect variations in the magnitude of repulsive interactions in the molecules; on this basis, the anomeric effect does not arise through instability of the equatorial anomeric C—O bond. A destabilizing interaction appears to cause polarization of most C—H bonds in a molecule, 13C becoming more shielded, and 1H less shielded, suggestive of a concerted means for delocalizing the instability. In comparing anomers or epimers, this polarization is evident as a reordering of the shielding state of different nuclei, e.g., for several sugars and their glycosides increased shielding of 13C-1 is accompanied by deshielding of the bonded H and increased shielding of the appended O—H or methoxyl 13C nucleus.
β-Ketoalkylthioacrylic acid derivatives as precursors of thiophenes, thiazolines, and thienopyrimidines
Authors: Laliberté Réal , Médawar Georges
Published: May 2006

Reactions of sodium salts of substituted 3-amino-2-cyano-3-thioacrylic esters and amides with α-halomethylketones were studied. Conditions were found which led to the synthesis of either 5-acyl-2,4-diaminothiophene-3-carboxylic esters and amides or thiazoline-Δ2α-acetic esters and amides. Some thiophene-3-carboxamides were also transformed into thienopyrimidines upon acetylation.
Magnetic resonance studies of metal–olefin complexes. I. Electron spin resonance spectra of γ-irradiated silver perchlorate cycloalkene complexes
Authors: Gee D. R. , Russell K. E. , Wan J. K. S.
Published: May 2006

Paramagnetic species have been detected in γ-irradiated polycrystalline silver perchlorate – cycloalkene complexes at room temperature and identified as Ag+ cycloalkenyl radicals, with spin density on Ag decreasing from 4.6 to 1.5% with increasing size of the cycloalkenyl ring. The extent of the spin density on Ag increases with the stability of the parent complexes.
Photoaddition of α-diketones to olefins. Stereospecificity of the addition reaction
Authors: Chow Y. L. , Joseph T. C. , Quon H. H. , Tam J. N. S.
Published: May 2006

Phenanthraquinone (PQ) photolytically adds to cis- and trans-alkenes to give a mixture of cis- and trans-1,4-dioxenes and two reduction products. The ratios of cis- to trans- 1,4-dioxenes remain the same irrespective of the photoaddition to cis- or trans-alkenes and are 1:1 for 2-butenes, 6:4 for 3-hexenes, and 8:2 for cyclohexene. A triplet excited phenanthraquinone is proposed as the reactive species which initiates the addition leading to the intermediate diradical 10. Depending on the nature of addenda the diradical 10 may be stabilized by a charge transfer structure in different conformations leading to the observed stereochemistry of the adducts. The PQ fails to add to fumaronitrile photolytically or thermally and thermally adds to 2-butenes only inefficiently. Biacetyl undergoes photoreduction readily in the presence of a large excess of cyclohexene.
The ternary system silver–indium–aluminum
Authors: Campbell A. N. , Wagemann R.
Published: May 2006

A number of alloys have been examined microscopically. From these observations, from the equilibrium diagrams of the component binary systems, and from the application of the phase rule, a room temperature isothermal section has been deduced. Three vertical sections through the ternary system have been partially constructed from differential thermal analysis. These data show that invariant planes occur at 143, 148, 241, and 506 °C. From the information obtained from the vertical sections and the room temperature isothermal section, isothermal sections have also been proposed at 143 and 148°. The transformation at the 143 °C invariant plane is a ternary eutectic, at 148° a ternary peritectic, and the other transformations at 241 and 506° are also ternary peritectics.Some evidence indicates that the ξ-phase of Ag–Al system and the γ-phase of Ag–In system link up through the ternary system forming a single phase region, and that such may also be the case with the phases µ and α′ of the systems Ag–Al and Ag–In, respectively. The phases ε and [Formula: see text] of the system Ag–In do not appear to be capable of dissolving aluminum appreciably.
Infrared spectra and the molecular conformations of some aliphatic amines
Authors: Krueger P. J. , Jan J.
Published: May 2006

The presence of two CD stretching bands for (CH3)2CDNH2 in dilute CCl4 solution is interpreted in terms of two conformations differing in enthalpy by 0.12 ± 0.02 kcal/mole. The low frequency component is assigned to the thermodynamically more stable conformer with the CD bond trans to the N lone pair. Similar rotational isomerism is observed in CH3CD2NH2 and CD3CH2NH2. Band contours for the NH stretching vibration in some N-alkyl anilines reported previously are also interpreted in terms of rotational isomerism and a change in hybridization of the N atom when the lone pair is trans to an α-CH bond, which results in an increase in vNH and a decrease in vCH.
Mechanism of a base-catalyzed carbonium ion rearrangement
Authors: Sorensen T. S. , Miller I. J. , Urness C. M.
Published: May 2006

The rearrangement of cis-1,2,3,4,5-pentamethylcyclopentenyl cation to the trans isomer in aqueous sulfuric acids has been found to follow H0 with unit slope (d log krearr• = •dH0). This rearrangement involves the intermediacy of a neutral compound, 1,2,3,4,5-pentamethylcyclopentadiene, which on reprotonation is only partly efficient in leading to the trans ion product. Under both steady-state intermediate and direct protonation conditions, this diene protonates to give about 55 % of the cis ion and only 45 % of the thermodynamically more stable trans isomer.
Cyanoethylations and Michael additions. V. The synthesis of allylic cyclohexenols by γ-cyanoethylation of α,β-unsaturated aldehydes and ketones. Part V
Authors: Engel Ch. R. , Salvi V. S. , Ruest L.
Published: May 2006

It is shown that the cyanoethylation of 3β-acetoxy-21-methyl-5α-pregn-17-en-21-one results in part in the addition of acrylonitrile to the γ-position, with concomitant cyclization, and that therefore the cyclo-γ-cyanoethylations of α,β-unsaturated carbonyl compounds reported previously were not confined to aldehydes. However, the main reaction products of the conjugated ketone were α-cyanoethylated derivatives. A variation of the reaction time did not affect the proportion of α- and γ-cyanoethylated products; the implications of this finding on mechanistic considerations are discussed; in particular, an explanation based on the assumption of an equilibrium between reactants and α- and γ-cyanoethylated products is ruled out. It is shown that the γ-additions observed, particularly in the case of α,β-unsaturated aldehydes, are not due to steric hindrance, neither to an abnormal charge distribution in the anion. It is further shown that in the presence of base the propionitrile moiety of oxygen-cyanoethylated α,β-unsaturated aldehydes with a suitable geometry is transferred to the γ-position of the original aldehyde and that cyclization occurs so that the same products are obtained from such cyano-enol ethers as in the direct cyanoethylation of the free aldehydes. On the basis of this finding, a mechanism for the cyclo-γ-cyanoethylations of α,β-unsaturated carbonyl compounds, involving such a transfer reaction, can be tentatively proposed.
The near-infrared spectra of some simple aldehydes
Authors: Lucazeau G. , Sandorfy C.
Published: May 2006

The near-infrared spectra of CH3CHO, CD3CHO, CH3CDO, CF3CHO, CHCl2CHO, and CCl3CHO were measured from 4000 to 9000 cm−1 in solution at room and liquid nitrogen temperatures. Assignments are made and cases of Fermi resonance are examined. A few potential and anharmonicity constants are obtained. Solvent effects affecting fundamentals and overtones are discussed.
Thermolysis of thiete 1,1-dioxide and related species
Authors: King J. F. , Mayo P. de , McIntosh C. L. , Piers K. , Smith David J. H.
Published: May 2006

Thiete 1,1-dioxide (1) rearranges to 5H-1,2-oxathiole-2-oxide (3) on heating in solution or in the vapor phase. The presence of phenol in the solution leads to formation of phenyl 2-propene-1-sulfonate (CH2=CHCH2SO2OPh) in 15% yield. The results are rationalized in terms of a mechanism involving vinylsulfene (2). Flash thermolysis of some thietane 1,1-dioxides (16) and 3-thietanone 1,1-dioxides (15) gave products derived from extrusion processes, but 3-thietanol 1,1-dioxide (17) yielded, among other products, acetaldehyde and formaldehyde. The latter is believed to arise by "desulfinylation" of sulfene (CH2=SO2) formed along with the enol form of acetaldehyde by cycloreversion from 17.
Gypsum, disodium pentacalcium sulfate, and anhydrite solubilities in concentrated sodium chloride solutions
Authors: Glew D. N. , Hames D. A.
Published: May 2006

The solubility of gypsum and anhydrite have been determined at 65 °C in aqueous 3.0 to 6.1 m NaCl solutions. Gypsum solubility at 30 °C has been determined in 5.9 m NaCl and in saturated sodium chloride. At 65 °C gypsum reacts with sodium chloride solutions more concentrated than 3.7 m NaCl to form disodium pentacalcium sulfate, Na2Ca5(SCO4)6•3H2O, which is isomorphous with calcium sulfate hemihydrate. The solubility of this double salt has been determined at 65 °C in aqueous 4.0 to 6.3 m NaCl solutions.
Structural preferences for the double bond position in some unsaturated 3,3-diphenylpyrrolidines
Authors: Hassan M. M. A. , Casy A. F.
Published: May 2006

The reaction between 3,3-diphenyl-3-cyano-1-methylpropyl isocyanate and ethyl magnesium bromide leads to 2-ethyl-5-methyl-3,3-diphenyl-1-pyrroline rather than the isomeric 2-ethylidenepyrrolidine. The protonated N-methyl analogue (identical with a major metabolite of methadone) retains the 1-pyrroline structure, but the free base is a cis-trans mixture of the corresponding 2-ethylidenepyrrolidines; the cis Me/Ph isomer preponderates and is the sole product (obtained as a quaternary salt) when the mixture is treated with methyl iodide. 5-Methyl-2-methylene-3,3-diphenylpyrrolidine, a lower homologue of the methadone metabolite, isomerizes to a 1-pyrroline derivative when protonated or methylated. All structural conclusions are based on i.r. and p.m.r. spectroscopic evidence.
Studies in isoxazole chemistry. IV. Isoxazoles via isoxazolines
Authors: Mlcetich R. G.
Published: May 2006

4- or 5-Chloro- or cyanoisoxazoles, 5-chloromethylisoxazoles, and 5-methylisoxazoles were made by the 1,3-dipolar cycloaddition of nitrile oxides to α-halogeno- or α-alkoxyolefins. In the case of cis- and trans-1,2-dichloroethylene, (5a and b) the intermediate cis- and trans-4,5-dichloroisoxalines (6a and b) were isolated. Both 6a and b were dehydrochlorinated with base to give the 4-chloroisoxazole (7a) exclusively. The cis-isomer 6a reacted faster than the trans-somer 6b. The reactions were found to be specific in every reaction since only one isomer was isolated. The structures of the products were established from n.m.r. spectral analysis.
An external heavy atom effect on biacetyl in the gas phase?
Authors: Jackson A. W. , Yarwood A. J.
Published: May 2006

The luminescence intensity of biacetyl in the gaseous phase at 303°K was studied, and the external heavy atom effect of xenon on the luminescence excited at 405 nm was re-examined. The effect on the phosphorescence lifetime was also investigated. In contrast to an earlier report, the external heavy atom effect of xenon on the triplet state of biacetyl is very small and probably negligible.
Studies of the Hot Water Extractives of the Bark and Leaves of Populus deltoides Bartr.
Authors: Pearl Irwin A. , Darling Stephen F.
Published: May 2006

The hot water extractives of the fresh smooth green bark and the fresh leaves of a Populus deltoides Bartr. tree cut in June and processed by the Waring Blendor technique in ethanol were extracted fractionally with ethyl acetate, and the individual ethyl acetate extracts were fractionated by elution chromatography with water, 20% ethanol, and 50% ethanol on polyamide columns. Important components found in the bark were salicortin, salicin, salicyl alcohol, pyrocatechol, ω-salicyloylsalicin, grandidentatin, grandidentoside, populoside, trichocarposide, and 6-methyldihydroquercetin. Important components found in the leaves were salicortin, salicin, salicyl alcohol, pyrocatechol, 1-O-p-coumaroyl-β-D-glucoside, populoside, ω-salicyloylsalicin, chrysin-7-glucoside, and a new glucoside, deltoidin, which has been identified as 2-O-salicyloylsalicin.
18O Transfer in the System Thiosulfate–Sulfite–Water: an Example of a Set of Consecutive Reversible First Order Rate Processes
Authors: Betts R. H. , Libich S.
Published: May 2006

The rate and mechanism of transfer of oxygen between thiosulfate ion and water, in the presence of sulfite, has been investigated with 18O-enriched Na2S2O3. The principal path, for the conditions examined, is via sulfur atom transfer between sulfite and thiosulfate, accompanied by oxygen atom transfer between sulfite and the solvent water. The latter path is suppressed at high pH, and oxygen transfer from thiosulfate proceeds to the sulfite stage only. At intermediate pH, the two processes have comparable rates, and the kinetics show the behavior expected for a system of consecutive, reversible first order processes. Under these conditions sulfite is observed to behave as a true intermediate, first accumulating 18O from thiosulfate, and then releasing it to the solvent water.
Fluorinated Carbohydrates. Part VIII. Studies of Some 3-Deoxy-3-fluoro-D-pyranosyl Fluorides
Authors: Hall L. D. , Johnson R. N. , Foster A. B. , Westwood J. H.
Published: May 2006

Detailed analyses have been made of the 1H and 19F n.m.r. spectra of the α- and β-anomers of 2,4,6-tri-O-acetyl-3-deoxy-3-fluoro-D-glucopyranosyl fluoride and of 2,4-di-O-acetyl-3-deoxy-3-fluoro-β-D-xylopyranosyl fluoride. The 4JF,F, couplings demonstrate a stereospecific dependence with 4Ja,a = + 10.4, 4Ja,e = + 1.0, and 4Je,e = −3.0 Hz.
Dibenzo[a,d]cycloheptene and Related Compounds. III. The Synthesis of Some Analogues of Methadone Containing the Dihydrodibenzo[a,d]cycloheptene and the Tetrahydrodibenzo[a,d]cyclooctene Ring Systems
Authors: Horning D. E. , Muchowski J. M.
Published: May 2006

The synthesis and spectral properties of some two- and three-carbon ortho-bridged analogues of the analgesic methadone are described. These compounds were devoid of analgesic activity.
Synthesis of 2,3-Dihydrotriquinacen-2-one
Authors: Russo Robert , Lambert Yvon , Deslongchamps Pierre
Published: May 2006

A synthesis of the title compound from Thiele's acid is reported.
Some Potentially Physiologically Active β, β-Diphenylethylamines Derived from Adrenaline
Authors: Forrest Janet E. , Kasparek S. , Heacock R. A. , Forrest T. P.
Published: May 2006

not available
The Flash Photolysis of Tetraphenyldiphosphine, Triphenylphosphine, and Diphenylphosphine in Alcohols
Authors: Wong S. K. , Sytnyk W. , Wan J. K. S.
Published: May 2006

The photochemical reactions of tetraphenyldiphosphine, triphenylphosphine, and diphenylphosphine in alcohol were studied by flash photolysis and product analysis. The primary photochemical process of all three phosphines studied appeared to be the formation of diphenylphosphinyl radicals which subsequently abstract α-H atoms from the solvent alcohol. The relationship between the rate constants of the abstraction and the α-H bond energies of various alcohols was examined.
Transannular Reactions in the Dibenzo[a,d]cycloheptene Series. V. Preparation of 10,11-Dihydro-5,10-(iminomethano)-5H-dibenzo[a,d]cycloheptenes
Authors: Dobson T. A. , Davis M. A.
Published: May 2006

Treatment of the ketonitrile 2a with sodium borohydride gave the lactone 3a which underwent ammonolysis to give 10,11-dihydro-5,10-(iminomethano)-5H-dibenzo[a,d]cyclohepten-13-one (5a). This compound was used to prepare a number of 12- and 11,12-disubstituted derivatives of the ring system.
Crystal Structure of Ca3(AsO4)2
Authors: Gopal R. , Calvo C.
Published: May 2006

Ca3(AsO4)2 crystallizes in the rhombohedral space group R3c with unit cell parameters a = 14.05(1) Å, α = 45.05(2)°, and ZR = 7. The equivalent hexagonal axes are a = 10.77(1) and c = 37.81(3) Å with ZH = 21. The structure was refined, using 769 symmetry independent reflections and a full matrix least squares program from a trial structure obtained from Patterson functions, to a final R value of 0.063. The structure consists of interconnected chains of CaOn polyhedra and AsO4 tetrahedra paralleling the c axis. The six chains surrounding the three-fold axes are each much like those in Ba3(PO4)2 with 3Ca followed by two AsO4 groups per half cell. The chain on the three-fold axis has only one AsO4 per half cell with one and half cations between adjacent arsenic atoms. The mean As—O bond lengths are 1.69, 1.65, and 1.69 Å for the three independent tetrahedra. The cation sites show coordination to 6, 7, or 8 oxygen atoms in contrast to the 10 or 6 + 6 found in Ba3(PO4)2. These structural differences arise primarily from the shorter cation – oxygen atom bond lengths in this compound. This structure is the same as that of Ca3(VO4)2 and although closely related to that of Whitlockite differs from it because of the need to accommodate hydrogen atoms in the latter compound.
N-Bromosuccinimide-Induced Dimethyl Sulfoxide Oxidation of Acetylenes
Authors: Wolfe Saul , Pilgrim W. R. , Garrard T. F. , Chamberlain P.
Published: May 2006

The addition of less than 2 mol equiv. of N-bromosuccinimide (NBS) to a solution of diphenylacetylene in anhydrous dimethylsulfoxide (DMSO) leads to the formation of benzil in near-quantitative yield at room temperature. Under the same conditions stilbene gives the dibromo adduct. The conditions for this novel oxidation of an acetylene have been examined in some detail and it has been established that anhydrous DMSO must be employed as the solvent and that NBS is uniquely able to induce the oxidation. Preliminary studies indicate that alkyl aryl, dialkyl, and terminal acetylenes are converted to the corresponding α-dicarbonyl compounds, and that diphenylbutadiyne is oxidized to diphenyltetraketone. Optimum conditions for these latter oxidations have not yet been established.
Total Synthesis of α,β-DL-Allose and α,β-DL-Galactose. Stereoselective cis-Hydroxylation by Osmium Tetroxide
Authors: Singh U. P. , Brown R. K.
Published: May 2006

The reaction of osmic acid with 1,6-anhydro-3,4-dideoxy-β-DL-erythro-hex-3-enopyranose and its 2-O-methyl and 2-O-acetyl derivatives in either pyridine or dioxane solution has produced 1,6-anhydro-β-DL-allopyranose and 1,6-anhydro-β-DL-galactopyranose and the corresponding 2-O-methyl and 2-O-acetyl derivatives. These or their fully acetylated derivatives could be hydrolyzed to α,β-DL-allose and α,β-DL-galactose and the 2-O-methyl derivatives. The proportion of allo to galacto product obtained varies widely with the solvent used in hydroxylation, showing that attack by osmic acid is subject to steric control.
Removal of Wood Components During Chlorite Delignification of Black Spruce
Authors: Ahlgren P. A. , Goring D. A. I.
Published: May 2006

The pattern of component removal has been studied for black spruce during delignification by acidified sodium chlorite at 70 °C. Special emphasis was placed on the determination of the acid soluble portion of lignin remaining in the sample.It was found that the chlorite procedure is selective in removing lignin only during the first 60% of delignification. At later stages of delignification some glucomannan is dissolved. A so-called holocellulose of 70% yield is thus composed of about 40% cellulose, 13% glucomannan and galactan, 12% xylan and other carbohydrates, and 5% lignin (all based on the original wood).
Polysaccharides of the Red Alga Rhodymenia pertusa Part II. Cell-Wall Glucan; Proton Magnetic Resonance Studies on Permethylated Polysaccharides
Authors: Whyte J. N. C. , Englar J. R.
Published: May 2006

The cell-wall polysaccharide from R. pertusa has been shown, by g.l.c, mass spectrum, and p.m.r. studies on the methylated derivative, to consist of β-(1 → 4)-linked-D-glucopyranose residues. The assessment of anomeric configuration in polysaccharides by p.m.r. spectroscopy is illustrated by the spectra of methylated amylose and cellulose. The preparation of anilides for mass spectral analysis of sugars is suggested.
Kinetic Isotope Effects in the Radiation-induced Oxidation of Alcohols by Hydrogen Peroxide in Aqueous Solution
Authors: Burchill C. E. , Thompson G. F.
Published: May 2006

By using selectively deuterated alcohols it is demonstrated that abstractions from both α and β positions of 2-propanol and ethanol contribute to the overall mechanism for the radiation-induced chain oxidation of these alcohols by hydrogen peroxide. Kinetic isotope effects are measured for abstraction of H by OH from 2-propanol and ethanol at both α and β positions and for the H atom transfer reaction from the alcohol to the β radical. The chain oxidation of methanol shows no primary kinetic isotope effect on substitution of CD3OH.
Tricyclic Unsaturated Hydrocarbons
Authors: Wightman R. H. , Wain R. J. , Lake D. H.
Published: May 2006

Some new unsaturated tricyclic hydrocarbons have been synthesized using a sequence of some general usefulness.
Empirical σ Molecular Orbital Parameters and their Correlation with Rates of Substitution Reactions in Quadrate Cr(III) and Co(III) Complexes
Authors: Langford C. H.
Published: May 2006

Empirical measures of σ bonding involving metal 3d orbitals are derived from Perumareddi's (4) complete analysis of the quartet spectral bands of quadrate complexes in the families Cr(NH3)5Xn+ and Cr(OH2)5Xn+. These are shown to correlate with lability of X in the Cr(III) complexes and in Co(NH3)5Xn+ complexes in a sense indicating that relative reactivity is controlled by variation of ligand metal 3d σ interaction. The relationship between the two Cr(III) series implies that the non-labile ligands can labilize the leaving group in proportion to their σ donor capacities. This observation bears on some well-known difficulties in crystal field theories of reactivity. In evaluating the correlation of spectral parameters with reactivity, the role of solvation in reactivity of Cr(III) and Co(III) complexes is discussed with emphasis on the surprisingly small solvent effects that have been observed.
Thermodynamic Investigation of the Reaction: by Electromotive Force Measurements
Authors: Espelund A. W. , Flengas S. N.
Published: May 2006

The thermodynamic properties of the system CoO–CoSO4 have been investigated over the temperature range 560 to 916 °C, by an electrochemical method using a ZrO2–CaO solid electrolyte and an oxygen reference electrode. The standard free energy change for the reaction[Formula: see text]can be expressed by[Formula: see text]and is given with an accuracy of ± 400 cal.
Orientation in the Crossed Aldol Condensation of Chloral with Unsymmetrical Aliphatic Ketones
Authors: Kiehlmann Eberhard , Loo Pui-Wah
Published: May 2006

The reactivity of a series of 14 aliphatic ketones in the crossed aldol condensation with chloral has been studied in glacial acetic acid and in dimethoxyethane. The reaction is irreversible and not accompanied by dehydration of the resulting 1,1,1-trichloro-3-hydroxy-4-alkanones. Except for butanone, condensation occurs preferentially at the least-hindered position of an unsymmetrical ketone. The α-methyl/α-methylene condensation product ratio obtained from ketones of the general formula RCH2COCH3 is higher in acetic acid than in dimethoxyethane as solvent when sodium acetate is used as catalyst. The steric size and chain length of the alkyl groups of methyl alkyl ketones have a marked effect on the reactivity of the α-methyl group toward chloral. Condensation at the α-methylene group results in the formation of diastereomeric ketols which epimerize under the preparative reaction conditions.
Refinement of the Structure of Mg3(VO4)2
Authors: Krishnamachari N. , Calvo C.
Published: May 2006

Magnesium orthovanadate crystallizes in the orthorhombic space group Cmca with a = 6.053(3), b = 11.442(6), c = 8.330(3) Å, and Z = 4. The structure was refined by full matrix least square methods to a final R value of 0.047 using 1697 reflections measured by a quarter circle General Electric automatic diffractometer. The structure was assumed to be isomorphous with that of Ni3(VO4)2, reported by Durif and Bertaut (2), and the refinement started using the same fractional atomic coordinates. The structure consists of nearly cubic closest packing of oxygen atom layers roughly normal to the [Formula: see text] direction with the Mg ions in two types of octahedral sites and the V ion in a tetrahedral site. The VO4 group has a crystallographic mirror plane. The cations lying on sites of Cm symmetry show an average Mg—O bond length of 2.092 Å, compared to 2.098 Å for cations lying at sites of C2h symmetry. The anion deviates significantly and substantially from regularity with the three oxygen atoms shared with only two cations showing V—O bond lengths within 0.015 Å of their mean, 1.70 Å, whereas the remaining oxygen atom, which is shared with three Mg ions, lies 1.809 Å from the V ion. The structure has characteristics similar to those of spinel.
Indole Oxidation: the Dimer of 3-Hydroxy-2,3-dimethylindolenine
Authors: Dave Vinod , Warnhoff E. W.
Published: May 2006

Chemical and spectroscopic evidence for the structure 1 of the dimer of 3-hydroxy-2,3-dimethyl-indolenine is presented. This evidence is based mainly on a comparison of the spectroscopic properties and reactions of both the dimer 1 and its hexadeutero analog 13. The stereochemistry derived by consideration of n.m.r. shielding is that found by the X-ray analysis of other investigators. The various ways in which this dimer can arise are discussed critically.
A Re-examination of the Yields in the High Dose Rate Radiolysis of Gaseous Ammonia
Authors: Boyd A. W. , Willis C. , Miller O. A.
Published: May 2006

Eyre and Smithies have recently obtained radical yields of [Formula: see text] in the radiolysis of gaseous ammonia. The consistency of these with N2, H2, and N2H4 yields obtained in the high dose rate radiolysis of NH3 and NH3–C3H6 mixtures has been shown by numerical integration of the rate expressions in a simple radical mechanism. These calculations give a value of 2.1 ± 0.5 × 1010 M−1 s−1 for the reaction of H atoms and NH2 radicals and a ratio of recombination to disproportionation of 6:1.
Further Investigations on the Chemistry of Fulvic Acid, a Soil Humic Fraction
Authors: Khan S. U. , Schnitzer M.
Published: May 2006

The fractionation scheme described in this and in an earlier paper resulted in the isolation and identification of about 2.0 g of pure components from 100 g of fulvic acid. About 28% of these compounds were phenolic acids, 19% benzenecarboxylic acids, 13% alkanes and fatty acids, and 40% dialkyl phthalates. The isolation of appreciable amounts of dialkyl phthalates was somewhat surprising but their presence was shown not be an artifact. The KMnO4 oxidation of the same fractions increased the yields of methylated phenolic and benzenecarboxylic acids by between 3 and 11 times.Following KMnO4 oxidation of methylated but unfractioned fulvic acid, the yield of phenolic and benzenecarboxylic acids increased substantially. The increased yields, after oxidation, of the same compounds as those that were separated without oxidation indicate that either these compounds originated from more complex structures or that they came from a structure of the type proposed earlier, which consists of phenolic and benzenecarboxylic acids joined by hydrogen-bonds, on which alkanes, fatty acids, and dialkyl phthalates are adsorbed.
Acid-catalyzed Solvolysis of Isonitriles. I
Authors: Lim Y. Y. , Stein A. R.
Published: May 2006

The acid-catalyzed hydrolysis of methyl isonitrile has been examined. The initial hydrolysis product is N-methylformamide which is further hydrolyzed to methyl amine and formic acid at a much slower rate. The hydrolysis to N-methylformamide is pseudo-first order in methyl isonitrile and shows a linear rate dependence on concentration of general (buffer) acid at fixed pH. The significance of general acid-catalysis in terms of the mechanism of the hydrolysis is considered and taken as evidence for carbon protonation rather than nitrogen protonation as the initiating step.
Ozonolysis of Acetals. (1) Ester Synthesis, (2) THP Ether Cleavage, (3) Selective Oxidation of β-Glycoside, (4) Oxidative Removal of Benzylidene and Ethylidene Protecting Groups
Authors: Deslongchamps Pierre , Moreau Claude
Published: May 2006

Ozone reacts very smoothly with acetals to give the corresponding esters. Tetrahydropyranyl ethers, β-glycopyranosides, ethylidene, or benzylidene derivatives are also oxidized whereas the α-glycopyranosides are inert.
Kinetics and Thermodynamic Data for the Hydrogen Fluoride Addition to Vinyl Fluoride
Authors: Moore Leonard O.
Published: May 2006

The kinetics of the addition of hydrogen fluoride to vinyl fluoride have been measured in the vapor phase at temperatures of 100 and 150 °C and under pressures of 170, 308, and 446 N/m2. The rate equation was found to be a typical second order expression, −dx/dt = k [CHF=CH2] [HF]. The energy of activation was calculated to be 17 ± 2 kcal/mol, and the frequency factor, log A (l/mol s) was 6 ± 1. Based on reaction data from the literature, equilibrium constants and a value for ΔH298 were calculated. For this reaction, ΔH298 is about −12 kcal/mol.
Viscosities, Densities, and Refractive Indices of Binary Liquid Mixtures
Authors: Katz Miguel , Lobo Pedro W. , Miñano A. Sancho , Sólimo Horacio
Published: May 2006

The viscosities, densities, and refractive indices at 25, 30, 35, and 40 °C were determined for the systems: aniline + toluene (A + T), N,N-dimethylaniline + toluene (DMA + T), and aniline + n-butanol (A + B). From the experimental results the excess volume, excess viscosity, and excess molar free energy of activation of flow were calculated. The deviations from ideality for the excess thermo dynamic functions are more important for the systems (A + T) and (A + B) than for (DMA + T). This fact is explained by the existence of dispersion forces in the mixture and by the presence of hydrogen bonds in pure aniline and pure butanol.
Thermodynamic Constants of Tetracyanoethylene Complexes with Methylated Benzenes
Authors: Liao S. C. , Chan R. K.
Published: May 2006

Formation constants, and enthalpy, free energy, and entropy changes for the tetracyanoethylene complexes with a complete series of methyl-substituted benzenes have been evaluated from the charge-transfer spectra over a temperature range of 1−50 °C in carbon tetrachloride solutions. From the literature data, it is deduced that various competing side interactions may not be significant compared to 1:1 electron donor–acceptor complex formation under certain experimental conditions. Some correlations among thermodynamic properties and vertical ionization potentials of the donors are discussed.
Oxidation of Hydrocarbons. III. Kinetics and Mechanism of the Oxidation of Arenes by Aqueous Sodium Dichromate
Authors: Lee Donald G. , Spitzer Udo A.
Published: May 2006

The kinetics of the Oxidation of several sodium p-alkylbenzenesulfonates by aqueous dichromate have been studied under slightly acidic conditions (pH = 7.0 to 5.4). The results indicate that the only active oxidant under these conditions is the acid chromate ion, HCrO4−, and that the reaction probably involves a free radical process.
The Influence of Sulfoxides and Sulfones on the Temperature of Maximum Density of Water
Authors: Macdonald Digby D. , Smith M. D. , Hyne J. B.
Published: May 2006

The influence of dimethyl sulfoxide (DMSO), diethyl sulfoxide (DESO), tetramethylene sulfoxide (TMSO), and tetramethylene sulfone (TMSO2) on the temperature of maximum density of water bas been investigated. It is concluded that in dilute solution DESO stabilizes the characteristic three-dimensional structure of water. The other solutes, however, destabilize the structure of water over the entire concentration range studied (0–1.3 × 10−2 mole fraction solute).