bluuebunny/crossref_metadata_2025 huggingface dataset:
Magnetic Field Effect on Electrochemiluminescence of Carbazole
Authors: Santhanam K. S. V.
Published: May 2006

Effect of magnetic field on electrochemiluminescence of carbazole has been studied in N,N dimethylformamide. The emission intensity increases with increasing applied field with a tendency to decrease at high magnetic fields. An explanation involving perturbation of triplet–triplet annihilation rate is proposed.
Studies on Microcapsules. XII. Preparation and Characterization of Carboxylated Polyphthalamide Microcapsules
Authors: Shigeri Yoshimichi , Tomizawa Michiko , Takahashi Kikuko , Koishi Masumi , Kondo Tamotsu
Published: May 2006

Carboxylated polyphthalamide microcapsules were prepared by utilizing the interfacial polycondensation reaction between basic amino acids in water and p-phthaloyl dichloride in organic solvent. The yield of the microcapsules was found to be dependent on the concentration of emulsifier in the organic solvent and temperature. The microcapsules moved towards the anode in an electric field irrespective of the pH of the medium owing to the presence of carboxylic groups in the membranes. Cation binding experiments indicated an increasing order, Al3+ > Mg2+ > Cs+ > K+, NH4+, Na+ > Li+, for the binding of these cations to the microcapsules.
Proton Magnetic Resonance Spectrum of 2-Chloroaniline-15N. Long-range Coupling Constants to Amino Protons from all Ring Protons
Authors: Wasylishen R. , Schaefer T.
Published: May 2006

The p.m.r. spectra of 2-chloroaniline and 2-chloroaniline-15N in benzene and toluene solutions are analyzed at 60 and 100 MHz under conditions where the amino protons are exchanging intermolecularly and also where they are not exchanging. The spectrum of 2-chloroaniline-H15ND in the absence of amino proton exchange is observed between −48 and 80 °C. In all situations fast rotation about the C—N bond evidently occurs. Long-range couplings of the amino protons to all ring protons are observed and their signs are determined. The nonplanarity of the amino group is discussed in terms of the long-range couplings, of the one-bond 15N–H couplings, and of the two-bond H–H couplings in the amino group. The signs and magnitudes of the coupling constants between the ring protons and 15N are also determined.
On the Blue Complexes Formed in Acidic Solutions of Hexaammineruthenium(II)
Authors: Bottomley F. , Tong S. B.
Published: May 2006

The blue complex formed by reaction of hexaammineruthenium(II) dichloride and hydrochloric acid bas been characterized by analytical, spectroscopic, electrochemical, and chemical methods as a chlorobridged ruthenium(II)–ruthenium(III) dimer, [Ru2(NH3)6Cl4H2O]Cl. With hydrobromic acid the analogous complex [Ru2(NH3)6Br4H2O]Br is formed. Reactions of the complexes with ammonia and hydrohalic acids are reported.
Raman and Infrared Spectra of Crystalline OF2
Authors: Tremblay J. , Savoie R.
Published: May 2006

Raman and infrared spectra of crystalline OF2 indicate that this solid is not centro-symmetric and contains at least two molecules per primitive cell, on sites of symmetry Cs or C1.
Configurational Equilibria in Methyl 3,6-Dideoxy-3-nitro-α-L-hexopyranosides
Authors: Kovář Jan , Čapen Karel , Baer Hans H.
Published: May 2006

Epimerizations in alkaline medium, by which the methyl 3,6-dideoxy-3-nitrohexopyranosides having the α-L-gluco (1), α-L-galacto (2), α-L-manno (3), and α-L-talo (4) configurations are mutually interconverted, were investigated quantitatively by n.m.r. spectroscopy and by preparative separation of products. The epimeric equilibrium compositions obtained depend on whether an equimolar or a catalytic amount of alkali is supplied. In the first case they are governed by the thermodynamic stabilities of the nitronate anions [Formula: see text], and in the second case, by those of the free nitro glycosides [Formula: see text]. The results are discussed in terms of conformational analysis, and a value of 2 kcal/mol is found for the contribution of the A(1,3) interaction to the conformational free energy in the nitronates. The A(1,3) effect strongly influences not only the product composition at the nitronate equilibrium but also the pathway of epimerization.
The Condensation of Cyclohexanone with Furan and Pyrrole
Authors: Brown W. H. , Hutchinson B. J. , MacKinnon M. H.
Published: May 2006

Several compounds formed by the acid-catalyzed condensation of cyclohexanone with furan and pyrrole have been isolated and identified. A previously-reported structure for one of the products of the condensation of cyclohexanone with pyrrole has been shown to be incorrect.
Electrophilic Substitution in Methyl-substituted Naphthalenes III. Correlation between Experimental Results and Molecular Orbital Calculations of Reactivity Indices
Authors: Canonne P. , Huy Le-Khac , Forst W.
Published: May 2006

Common reactivity indices (electron density qr,self-polarizability πrr, frontier electron density fr, superdelocalizability Sr, and localization energy Lr) are calculated for electrophilic substitution in 25 methyl-naphthalenes. An elementary s.c.f. method in the form of a modified ω-technique is used, using the hyperconjugative-heteroatom model for the methyl groups, with ω = 1.4, hx = 2.0, kc–x = 0.8. This choice gives reasonably good ionization potentials and very good correlation for singlet transitions (p-band) in u.v. spectra of α-methylnaphthalenes. Purely static indices qr, fr, and πrr are found to be unsuitable for predicting reactive positions for chloromethylation, while Sr and Lr are very satisfactory. On the theory that the polarizing effect of the approaching reagent is important, the index qr′ = qr + πrr δαr may be obtained, which is also found to be very satisfactory for δαr = β. If the interaction is viewed as an interaction between a hard acid (chloromethyl) and soft base (methylnaphthalenes), the index ΔEr = aqr + bfr is obtained, which is likewise found to be satisfactory with a = 1, b = 0.15. These results show clearly that it is insufficient to base reactivity considerations in methylnaphthalenes entirely on the properties of the isolated substrate molecule, but that even a very simple description of the substrate–reagent interaction is sufficient since the four indices Sr, Lr, qr′ and ΔEr all have the same predictive value.
Steric and Electronic Effects on the Stereochemistry and Molecular Structure of Nitrato Tris(diphenylmethylphosphine)Copper(I)
Authors: Mathew M. , Palenik G. J. , Carty A. J.
Published: May 2006

A single crystal X-ray study of (Ph2MeP)3CuNO3 revealed the presence of three different Cu—P distances and a unidentate nitrate group. Steric and electronic factors responsible for the unusual molecular dimensions of the nitrate group and the variation in Cu—P bond lengths and O—Cu—P bond angles are discussed.
Isotope Effects and Hydrogen Yields in the Radiolysis of H2O–D2O Mixtures at Very High Dose Rates
Authors: Boyd A. W. , Willis C. , Lalor G. C.
Published: May 2006

Total hydrogen yields and their isotopic ratios have been measured in the single pulse, high dose rate radiolysis of H2O–D2O mixtures and acidic, basic, and nitrous oxide solutions. The yield from D2O is ~11% lower than in H2O at 7 × 1027 eV g−1s−1. In acid solutions the yields from H2O and D2O are the same within 5%. This yield, G(H2) = 1.15 ± 0.05 has been used to derive a value of kH+OH = 2.5 ± 0.3 × 1010 M−1 s−1.Using the literature values for primary yield data and for the reaction rate constants, values of α have been determined for the various hydrogen forming processes by computer calculation. We obtain values for hydrogen formation of αspur = 2.1 ± 0.1, αe+e = 6.0 ± 0.1, αH+H (effective) = 3.2 ± 0.1, and αe+H (effective) = 1.3 ± 0.2. Detailed consideration of the mechanisms involved suggest that there are little or no isotopic preferences in H + H and e + H reactions.
Structure of Grandiflorenic Acid
Authors: Piozzi F. , Passannanti S. , Marino M. L. , Sprio V.
Published: May 2006

Grandiflorenic acid is determined to be structure 2, (−)-kaura-9(11),16-dien-19-oic acid.
Photolysis of Aqueous Solutions of 9,10-Anthraquinone-2-sulfonate. Part I. Dependence of Product Yields on Reaction Conditions
Authors: Broadbent A. D. , Newton R. P.
Published: May 2006

The products of the photolysis of neutral aqueous solutions of 9,10-anthraquinone-2-sulfonate or of the action of Fenton's reagent on this quinone have been identified as 1- and 2-hydroxy- and dihydroxy-9,10-anthraquinone sulfonates. High quinone and low oxygen concentrations favor production of monohydroxy-anthraquinone sulfonates, while low quinone and high oxygen concentrations result in preferential formation of dihydroxylated derivatives of the quinone. Photolysis in aqueous NaOH solution gives essentially only 2-hydroxy-9,10-anthraquinone sulfonates.
The Photochemistry of 1-Methoxy-1,4-dihydro-1,4-enthenoanthracene
Authors: Bender C. O. , Elder J. L. M. , Herbst A. J. , Miller L. E.
Published: May 2006

The primary photoproducts of direct and benzophenone sensitized irradiation of the barrelene 1-methoxy-1,4-dihydro-1,4-ethenoanthracene are the semibullvalenes 2- and 5-methoxynaphtho[2,3-c]tricyclo[3.3.0.02,8]-octa-3,6-diene (6 and 7), formed with quantum efficiencies of [Formula: see text] in each case. Whereas 6 is inert to further direct irradiation, 7 photoisomerizes to 6-methoxycycloocta[b]naphthalene (4) (Φ = 0.40); 4 photoisomerizes to 10b-methoxy-2a, 10a-dihydrocyclobut[a]anthracene upon direct (Φ = 0.11) or benzophenone-sensitized irradiation (Φ = 0.05).
Trapped Electrons and Radicals in γ-Irradiated Propylene Carbonate Glasses
Authors: Shaede Eric A.
Published: May 2006

Radicals formed by γ-irradiation of propylene carbonate (PC) glasses at 77 °K were studied by e.s.r. and optical spectroscopy. Trapped electrons were identified by their narrow (ΔHms = 4.5 G) Gaussian e.s.r. line at g = 2.0028 which was completely resolved from the radical spectrum. The trapped electrons were unstable at 77 °K. They decayed fairly rapidly via a process exhibiting non-homogeneous kinetics believed to be reaction with positive ions. The temperature dependence of the e.s.r. spectra of the other radicals formed is discussed although conclusive assignment of the lines could not be made.Ultraviolet photolysis of the radicals in the irradiated PC glasses produced new species identified as HCO, CO3−, and CH3 by their characteristic e.s.r. spectra. In addition, a complex optical absorption band in the 500–750 nm region was assigned to a combination of the absorption bands of the CO3− radical anion and the HCO radical.
Studies in Solubility Parameter Theory for Mixed Solvent Systems
Authors: Purkayastha Avijit , Walkley John
Published: May 2006

Data are presented for the saturation solubility and partial molal volume of iodine in a mixed benzene–cyclohexane solvent and for the saturation solubility of stannic iodide in the same solvent mixture. A successful interpretation of these data in terms of solubility parameter theory is possible if we define an effective volume fraction term. This term reflects the immediate solvent environment of the solute molecule with the preferential solvation of the solute by one of the solvent molecules. Data for iodine in a mixed carbon tetrachloride–benzene solvent mixture and for iodine in a carbon tetrachloride–perfluoroheptane mixture are also interpreted in terms of the proposed theory.
The Crystal and Molecular Structure of bis(triphenylphosphine)-(ethylene)platinum, (PPh3)2PtC2H4
Authors: Cheng P.-T. , Nyburg S. C.
Published: May 2006

The X-ray crystal structure analysis of the triphenyl–phosphine platinum ethylene complex (PPh3)2PtC2H4 is reported. The crystals belong to the monoclinic system a = 16.46(3), b = 10.85(2), c = 17.85(3) Å, β = 100.5(1)°, space group P21/a, Z = 4 molecules per cell.The ethylene C—C distance of 1.434(13) Å is in accord with that found when other transition elements form metallo-cyclopropanes. The structure has been refined by anisotropic full-matrix least-squares, the final R-factor being 0.043 for 4174 observed reflections.
Synthesis and Kinetic Behavior of Some trans-Diacidotetraamminerhodium(III) Complexes
Authors: Poë A. J. , Twigg M. V.
Published: May 2006

A greatly improved preparation of trans-dichlorotetraamminerhodium(III) chloride has been devised that makes use of trans-hydridoaquotetraamminerhodium(III) as an intermediate. The new complexes trans-[Rh(NH3)4Br2]Br and trans-[Rh(NH3)4I2]I have also been prepared. The kinetics of some reactions of the dichlorocomplex have been studied over a range of temperatures, and the rate parameters are compared with those for the reactions of the analogous bisethylenediamine complex.
A Total Synthesis of dl-Occidol
Authors: Ho Tse-Lok
Published: May 2006

dl-Occidol has been synthesized from 3,6-dimethylphthalic anhydride.
Synthesis of 8,2′-Thioanhydroguanosine
Authors: Ogilvie K. K. , Slotin L. , Westmore J. B. , Lin D.
Published: May 2006

The synthesis of 8,2′-thioanhydroguanosine is described. The anhydro ring is formed by displacement of bromine from position-8 and sulfonate from the 2′-position using sodium hydrogen sulfide.
Synthesis of Oligothymidylates on an Insoluble Polymer Support
Authors: Ogìlvie K. K. , Kroeker K.
Published: May 2006

The synthesis of a succinylated polystyrene polymer is described. The polymer is converted to the acid chloride form and condensed with thymidine derivatives. A number of methods for phosphorylation of polymer bound nucleosides were investigated and the synthesis of tetrathymidine triphosphate (TpTpTpT) is described.
The Crystal and Molecular Structure of Tetrameric Phosphonitrilic Isothiocyanate
Authors: Faught J. Brian
Published: May 2006

The crystal structure of tetrameric phosphonitrilic isothiocyanate, N4P4(NCS)8, has been determined by three-dimensional X-ray studies from data collected on a Picker FACS-1 automated diffractometer. The compound crystallizes in the triclinic space group [Formula: see text] with a = 8.098(8), b = 8.018(7), c = 9.937(10) Å, α = 104.08(7), β = 99.42(7), γ = 95.42(7)°, and one molecule per unit cell. The structure was solved from 1766 independent non-zero reflections and refined to a conventional R factor of 0.063. Nitrogen atoms of two isothiocyanate groups are bonded to each phosphorus atom of the eight-membered phosphorus–nitrogen ring. The ring has a chair configuration. The average dimensions of the structure are P—Nring = 1.543 + 0.017, P—Nisothiocyanate = 1.644 ± 0.011, N—C = 1.168 ± 0.008, C—S = 1.535 + 0.009 Å, [Formula: see text] [Formula: see text] [Formula: see text] [Formula: see text] and NĈS = 176.6 ± 1.1°.
Electron Spin Resonance Studies of Thiocarbonyl Anion Radicals
Authors: Aarons Leon J. , Adam F. C.
Published: May 2006

The temperature dependence of the e.s.r. spectra of a series of sodium reduced thiones is reported. The thioketyls thiobenzophenone, p,p′-dimethoxythiobenzophenone, xanthene-9-thione, thioxanthene-9-thione, and their ketone analogues have been studied. Several show temperature-dependent sodium hyperfine structure near room temperature, but dissociate at lower temperatures to give spectra of thioketyl anions with no sodium coupling and markedly different g-values. Ring proton hyperfine splittings are found to be independent of the ion pairing process and independent of temperature. Models of ion pairing are discussed. Comparison is made to uhf–scf–mo calculations.
Silver Plated Bimolecular Lipid Membranes
Authors: Petkau A. , Chelack W. S.
Published: May 2006

The electrochemical reduction of silver ions at the surface of a model phospholipid membrane proceeds without the application of an electric field. The silver deposition is dependent on I− and I2. The charge transfer complexes formed by iodine with phospholipids and cholesterol are the most probable donors for the electron transfer reaction. Cholesterol membranes do not show the silver deposition unless an external electrical field is applied. An account for the difference is given on the basis of dissimilar ion distribution profiles within phospholipid and cholesterol membranes.
The Constituents of Naucleadiderrichii. Part III. Indole-Pyridine Alkaloids
Authors: Murray D. G. , Szakolcai A. , McLean Stewart
Published: May 2006

Six alkaloids isolated from the bark of Naucleadiderrichii have been shown to have structures that contain both indole and pyridine units. Because of the small amounts available of each constituent, investigation of structure has been confined mainly to the application of spectroscopic techniques; these have shown that all of these alkaloids belong to the novel indole-pyridine class, and have led us to propose structures or part structures with varying degrees of confidence for each of the alkaloids. Structure 1 was deduced for naucledine, C18H15N3O2, and confirmed by synthesis. Its spectroscopic characteristics indicate that nauclederine, C19H19N3O2, has structure 3, but this has not yet been confirmed by synthesis. Evidence is presented that nauclechine, C21H21N3O3, has part structures 6 and 7, and it is suggested that these can be incorporated in structure 8. A working hypothesis for the structure of nauclexine, C18H17N3O2, is represented by 9. Two alkaloids, ND-363C, C21H21N3O3, and ND-305B, C19H19N3O, are closely related, the latter being formally derived from the former by removal of a carbomethoxy group; each appears to exist as an equilibratible pair of isomers containing an indolic (substituted β-carboline) and a pyridine part linked together in a manner which may incorporate a spiro carbinolamine ether (as in 12) that can form ring-opened or solvated derivatives in some solvents.
cis-5-Cyclooctene-1,2-dione and its Ethylene Ketals
Authors: Yates Peter , Lewars E. G. , McCabe P. H.
Published: May 2006

Oxidation of cis-cis-1,5-cyclooctadiene with hydrogen peroxide gives cis-5-cyclooctene-trans-1,2-diol (3) which is converted to cis-5-cyclooctene-1,2-dione (6) on treatment with dimethyl sulfoxide and acetic anhydride. Bromination of 6 is accompanied by transannular bonding to give a dibromo keto ether 9a or b. Ketalization of 6 with ethylene glycol gives a monoketal 11 and two diketals 12 and 13 with 1,3-dioxolane and 1,4-dioxane rings, respectively. Bromination of 12 with bromine or pyridinium perbromide is accompanied by transannular bonding and fission of one of the 1,3-dioxolane rings to give a dibromo monoketal ether 15a (or b). Bromination of 12 with N-bromosuccinimide followed by dehydrobromination gives a cyclooctadiene-1,2-dione diketal 20a (or b).
The Acid-catalyzed Isomerization of the Adducts of Azodiacyls with Cyclopentadiene and 1,3-Cyclohexadiene
Authors: Chung Miss C. Y-J. , Mackay Donald , Sauer T. D.
Published: May 2006

The isomerization of the Diels–Alder adducts of azodiacyls with cyclopentadiene and 1,3-cyclohexadiene is powerfully catalyzed by strong protic acids and by Lewis acids. In adducts from p-substituted azodibenzoyls with cyclopentadiene the catalytic effect increases with electron release by the substituent.
The Alkaloids of Ormosiasemicastrata: (−)-Ormosanine, (±)-Piptanthine, (−)-18-Epiormosanine, and (−)-Ormocastrine
Authors: McLean Stewart , Roy Marie Lessard , Liu H.-J. , Chu D. T.
Published: May 2006

The alkaloids of Ormosiasemicastrata have been shown to be (−)-ormosanine, (±)-piptanthine, (−)-18-epiormosanine, and (−)-ormocastrine. The structure and relative configuration shown in 1 have been assigned to ormocastrine on the basis of its 220 MHz n.m.r. spectrum and its conversion to ormosanine, among other products, on hydrogenation.
Equilibrium Constants for 2,3-Dihydroxypyridine and its Complex with Iron(III) in 1 M Hydrochloric Acid
Authors: Curtis K. E. , Atkinson G. F.
Published: May 2006

Improved values for two acidity constants of 2,3-dihydroxypyridine have been computed using program PITMAP. The composition of the complex with iron(III) and its conditional and overall stability constants in 1 M hydrochloric acid have been evaluated.
Cavitation-induced Reactions in Pure Substituted Benzenes
Authors: Diedrich G. K. , Kruus P. , Rachlis L. M.
Published: May 2006

The formation of polymers has been observed on exposure of pure substituted benzenes to ultrasound intense enough to cause cavitation. The products have some of the characteristics of the char obtained from low temperature pyrolysis of hydrocarbons. They are difficult to dissolve, melt above 300 °C, and give a large broad e.p.r. signal. A crude correlation between bond dissociation energy and the reaction rate suggests that the initiation reaction is a thermal decomposition in a cavitation bubble. The phenomenon is compared to radiolysis and thermal reactions.
The Synthesis and Structural Studies of some Dialkyltin(IV) Salts of Strong Monobasic Acids
Authors: Tan T. H. , Dalziel J. R. , Yeats P. A. , Sams J. R. , Thompson R. C. , Aubke F.
Published: May 2006

A number of dialkyltin(IV)-bisfluorosulfates, -bistrifluoromethanesulfonates, and -bisdifluorophosphates are synthesized by solvolysis of dialkyltin(IV) chlorides in an excess of the corresponding acid according to [Formula: see text] R = CH3, C2H5, n-C3H7, n-C4H9, and n-C8H17; X = SO3F, SO3CF3, and PO2F2. The structural proposals, hexacoordination for tin with the alkyl groups in trans-octahedral position and bidentate bridging anionic groups with coordination through oxygen, are based on 119Sn Mössbauer, infrared and, where obtainable, Raman spectra. The vibrational spectra of the difluorophosphates are discussed in detail. Variations in isomer shift and quadrupole splitting values with different alkyl groups in all three groups of compounds follow the same regular pattern as in the series R2SnF2. The results of point charge calculations are reported.
A Kinetic Study of the Oxidative Addition of Substituted Benzenethiols Towards trans-Halocarbonylbis(triphenylphosphine)iridium(I)
Authors: Gaylor J. R. , Senoff C. V.
Published: May 2006

The kinetics of the oxidative addition of a series of para-substituted benzenethiols, HSC6H4Y, where Y = 4-NO2, 4-Br, 4-Cl, 4-F, 4-H, 4-CH3, or 4-CH3O towards the complexes, trans-IrX(CO)(Ph3P)2 where X = Cl, Br, or I have been studied in benzene between 15 and 45°. These reactions follow simple second order kinetics, rate = k2[IrX(CO)(Ph3P)2][HSC6H4Y]. The two principal factors which influence the rates of these reactions are the mesomeric and inductive effects of the para-substituent and the nature of the ligand, X, coordinated to iridium. The rate of reaction increases as the substituent becomes more electron withdrawing and as X varies from Cl to Br to I. The kinetic data together with spectroscopic data (i.r. and n.m.r.) suggest that oxidative addition proceeds via a three-centered activated complex to give the cis-product.
Bond Scission in Sulfur Compounds. V. A Kinetic Study of Sulfur–Oxygen and Sulfur–Chlorine Bond Scission in the Methanolysis of p-Nitrophenyl Chlorosulfate
Authors: Buncel E. , Raoult A.
Published: May 2006

A kinetic study of the reaction of p-nitrophenyl chlorosulfate with methoxide ion in methanol has been carried out over the temperature range 5–35°. The results are discussed in terms of two bond scission processes, S—O and S—Cl scission. A stereo-electronic factor is considered dominant in discussion of activation entropies.
The Conformational Enthalpy, Entropy, and Free Energy of The Formyl Group Determined by Low Temperature Proton Magnetic Resonance
Authors: Buchanan G. W. , McCarville A. R.
Published: May 2006

The low temperature proton n.m.r. peak area method has been applied to the formyl proton of cyclohexanecarboxaldehyde. The conformational enthalpy and entropy of the CHO group have been measured for the first time. The results indicate that the axial conformation has the higher entropy and −ΔG0 for the CHO function is about 0.8 kcal/mol.
Electron Spin Resonance Spectrum of the tert-Butylperoxy Radical, B16O17O•
Authors: Howard J. A.
Published: May 2006

A tert-butylperoxy radical specifically labelled with 17O on the terminal oxygen has been prepared by photolysis of di-tert-butyl peroxide in perdeuterocyclopentane containing 17O enriched oxygen. The value of the 17O hyperfine coupling constant is 23.45 G.
Thermal Decomposition of Stereoisomeric 3-Aroyl- and 3-Carbomethoxyaziridines in Acetonitrile
Authors: Lown J. W. , Akhtar M. H.
Published: May 2006

The thermal decomposition of 1-alkyl-3-benzoyl-2-(m-nitrophenyl)aziridines in dry acetonitrile results in a series of autocatalytic hydrolytic cleavages, 1,3-dipolar additions, condensations, and rearrangements to give products including oxazolidines, 1,2-dihydropyrazines, pyrrolo-[3,4-d]-4-oxazolines, and α-aminoketones. The marked differences in product type and distribution from cis- and trans-aziridines are ascribed to preferential hydrolytic opening at the aziridinium ion stage. Complete equilibration of the stereoisomeric azomethine ylides takes place prior to 1,3-dipolar additions.Thermal decomposition of cis- and trans-methyl 1-isopropyl-2-(m-nitrophenyl)aziridine-3-carboxylates in acetonitrile is not autocatalytic (and can be suppressed) and produces three stereoisomeric oxazolidines in identical yields and ratios, and methyl N-isopropylglycine by selective hydrolytic attack at the 2-aziridine position. This result is ascribed to equilibration of the stereoisomeric aziridines prior to hydrolytic cleavage by adventitious moisture only.
The Triplet State of Ketene
Authors: McIntosh John S. E. , Porter Gerald B.
Published: May 2006

Ketene quenches the phosphorescence of both biacetyl and hexafluoroacetone. Although the quenching of hexafluoroacetone emission is nearly collision-controlled, that of biacetyl is much less efficient. The large difference in the rate constants is attributed to endothermic energy transfer from triplet biacetyl to ketene and exothermic energy transfer from triplet HFA to ketene. From the endothermicity, the lowest triplet state of ketene is estimated to be at 61 ± 1 kcal/mol above its ground state. No sensitized photodecomposition of ketene occurs as a result of energy transfer from either biacetyl or hexafluoroacetone.
4,6-O-(1-Carboxyethylidene)-D-mannose as a Structural Unit in Capsular Polysaccharide of Klebsiella K-type 5
Authors: Dutton G. G. S. , Yang M. T.
Published: May 2006

Methylation, periodate oxidation, and partial hydrolysis techniques have each been used to demonstrate the presence of 4,6-O-(1-carboxyethylidene)-D-mannopyranosyl units in the capsular polysaccharide of Klebsiella K-type 5. The structure of this polysaccharide differs from those known for other Klebsiella capsules by the lack of any carbohydrate side chain. A repeating unit of[Formula: see text](plus one unassigned O-acetyl group) is in accord with the experimental data.
Hindered Rotation in an o-Substituted Acetophenone
Authors: Dave Vinod , Warnhoff E. W.
Published: May 2006

In the substituted acetophenone 2, rotation is so restricted that the n.m.r. absorption of the methyl ketone is a broad band in several solvents at room temperature. At 90° this absorption becomes a sharp singlet, while at −60° it separates into two sharp peaks of unequal intensity. At −60° the n.m.r. absorption of the quaternary methyl groups of 2, 3, and 11 all show line broadening which is attributed to slowed rotation of these meshed vicinal methyl groups.
The Structure of Na4P2O7 at 22 °C
Authors: Leung K. Y. , Calvo C.
Published: May 2006

At room temperature Na4P2O7 crystallizes in the orthorhombic space group P212121 with a = 9.367(5), b = 5.390(2), c = 13.480(8) Å, and z = 4. The structure was refined by full-matrix least-squares using 1337 reflections measured with a Syntex Automatic diffractometer. The final R value is 0.022. The anion has nearly an eclipsed configuration with a P—O—P angle of 127.5(1)°. The two bridging P—O bond lengths are 1.631(2) and 1.642(2) Å with terminal P—O bond lengths averages of 1.512 and 1.514 Å on either side of the anion. Two of the four Na+ ions are coordinated to five oxygen atoms while the remainder are coordinated to six oxygen atoms. The structure contains chains of cations with four nearly collinear Na+ per cell paralleling the c axis. These are surrounded by six anions with the bridging oxygen atoms lying approximately at the corners of an octahedron with the P—P vector of the anion also paralleling the c axis. Adjacent anions along the c axis are separated by a pair of Na+ ions.
Infrared and Electronic Spectral Studies of Cobalt(II) and Nickel(II) Complexes of N-Allyl Urea and N-Allyl Thiourea
Authors: Singh P. P. , Pande I. M.
Published: May 2006

Complexes of N-allyl urea (NAU) and N-allyl thiourea (NATU) with cobalt (II) and nickel (II) halides and perchlorates have been prepared and characterized by electrical conductance, magnetic susceptibility, infrared and electronic spectra. Infrared spectra suggest coordination in NAU through oxygen and in NATU through nitrogen. The electronic spectra and magnetic susceptibility data indicate tetrahedral and octahedral stereochemistry for cobalt (II) and nickel (II) halide complexes, respectively. The various ligand field parameters Dq, B′, and β calculated for these complexes show about 25 and 11% covalency for Co (II) and Ni (II), respectively, and suggest a weak ligand field.
Kinetics of Charge Scavenging in γ Irradiated Liquids with Large Free Ion Yields
Authors: Dodelet Jean-Pol , Freeman Gordon R.
Published: May 2006

The extent to which the calculated scavenging yields are affected by the form of the ion–electron special distribution decreases as the free ion yield increases. The increasing free ion yield may be due to larger electron ranges or to a larger dielectric constant. The free ion yields in neopentane and water are respectively 1.0 (due to large electron ranges) and 2.7 (due to large dielectric constant). The scavenging yields in neopentane calculated with three different forms of spacial distribution, using the forced diffusion (FD) approximation, are significantly affected by the form of the spacial distribution. The scavenging yields in water calculated with four different forms of spacial distribution, using the FD approximation, are all within the experimental error of the measured yields. Use of the prescribed diffusion (PD) approximation permits satisfactory yields to be calculated for neopentane, but leads to the unsatisfactory result that all of the secondary electrons in the liquid have the same range (delta function distribution YD). The scavenging yield curves obtained using the PD approximation for water did not have a steep enough slope even when the distribution YD was used; YD leads to a steeper slope than any other form of distribution. The PD approximation gives an overestimate of the breadth of the geminate neutralization time distribution. The calculated time required for half of the geminate neutralization reaction to occur is similar whether the FD or PD approximation is used, but the spread of the neutralization times is an order of magnitude greater from the latter than from the former. Calculations were also done for electron scavenging in methylcyclopentane and in methanol. Methylcyclopentane behaves like cyclohexane and methanol behaves much like water with regard to the kinetics of ion–electron reactions in the spurs.
Metals Intercalated in Graphite. I. Reduction and Oxidation
Authors: Lalancette J.-M. , Rollin G. , Dumas P.
Published: May 2006

Potassium in graphite shows distinctive reducing properties towards carbonyls. The reaction products can be related to a mechanism similar to electrochemical reduction. The steric orientation of the reduction can be explained by the particular structure of potassium–graphite.Chromic anhydride in graphite offers a new selective method of preparation of aldehydes from the corre sponding primary alcohol. This method is characterized by its specificity, high yields and a simple experimental procedure.
Electrochemical Oxidation of Trifluoroacetic Acid in an Organic Medium. I. Synthesis of Trifluoroethane-1,1,1-d3 and Pentafluoropropane-1,1,1-d3
Authors: Renaud R. N. , Sullivan D. E.
Published: May 2006

"Crossed" Kolbe reactions are generally not very appropriate for the synthesis of short-chain hydrocarbons. However, trifluoroethane-d3 and pentafluoropropane-d3 were prepared in high yields by electrolysis of mixtures of the corresponding perfluoro-acids and acetic-d3 acid under specific conditions.
A Novel Solution to the Master Equation for Chemical Reaction
Authors: Boyd R. K.
Published: May 2006

It was found by McElwain and Pritchard (1c), as a result of numerical experiments on the transport matrix for the dissociation of H2, that an apparent correspondence existed between the eigenvalues λi and the pairs of transition probabilities (Ai,i−1;Ai−1,i). In the present work, a qualitative understanding of this result is attempted, using an unusual form of solution of the master equation.
Homogeneous Catalysis of D2–H2O Isotope Exchange by Pentacyanocobaltate(II)
Authors: Strathdee G. G. , Quinn M. J.
Published: May 2006

The rate of exchange of deuterium between hydrogen gas and water catalyzed by pentacyanocobaltate(II) has been measured as a function of pressure and temperature at a constant total cobalt concentration, 0.05 M, and ionic strength, 1 M. The rates of evolution of hydrogen from solutions of hydridopentacyanocobaltate(III) have been determined under identical conditions. These data have been employed to test the validity of a mechanism for the[Formula: see text] -catalyzed isotope exchange reaction, and to clarify the controversy over the magnitude of the specific rate for the deuterium transfer step[Formula: see text]Calculations show that kinetic isotope and ion pairing effects are significant.
Chaleurs de mélange du système éthyl-3 pentanol-3 tétrachlorure de carbone
Authors: Brusset H. , Desgranges M. , Lecoq J. C.
Published: May 2006

The enthalpies of mixing in the system 3-ethyl-3 pentanol–carbon tetrachloride were measured by microcalorimetry. The classic theory of associated solutions leads to an expression for the excess enthalpy which we have simplified by introducing the heat at infinite dilution for the alcohol. The resulting expression allows the enthalpy of formation of a hydrogen bond to be calculated using calorimetric and tonometric results. The calculations show that this enthalpy is independent of the concentration of the solution (up to 0.45 in molar fraction) and is in agreement with the literature.
Spectrofluorometric Studies. XI. Some Aspects of the Photochemistry of Ortho-fused Benzocycloalkenes
Authors: Grossman M. , Kubela R. , Semeluk G. P. , Unger I.
Published: May 2006

Fluorescent yields of[Formula: see text]excited in the 2500 Å region in cyclohexane solution have been examined. There is a general trend of fluorescent yields decreasing with increasing alkene ring size. The sum of the fluorescent and triplet yields decreases with increasing ring size. Triplet energies, obtained by Evans' method and roughly confirmed by phosphorescent emission spectra at 77 °K, do not vary greatly.
Phase Diagrams of Sodium Chloride and of Potassium Chloride in Water–Dioxane
Authors: Campbell A. N. , Lam S. Y.
Published: May 2006

The equilibrium conditions, at 25°, of the NaCl–water–dioxane and KCl–water–dioxane systems have been investigated. While water–dioxane mixtures separate into two layers in the presence of certain concentrations of sodium chloride, the system KCl–water–dioxane does not form two layers under any conditions. The LiCl–water–dioxane system has been previously investigated by Lynch (1).
Reaction of 2,3-Diphenylindole with Permanganate. Rearrangements of N,N′-Dimers
Authors: Dave Vinod
Published: May 2006

Based on spectroscopic and chemical evidence dimeric structure 1 is assigned to the major product from reaction of 2,3-diphenylindole and potassium permanganate. Thermal and acid-catalyzed rearrangements of N,N′-dimers 1 and 6 were studied.
The Effect of Aromatic Amines on the Catalyzed Decarboxylation of 3-Oxo-glutaric Acid
Authors: Leong K. N. , Lister M. W.
Published: May 2006

Equilibrium constants have been measured for the formation of MA species, where M is divalent manganese, cobalt, nickel, or zinc, and A2− is the 3-oxo-glutarate ion. Equilibrium constants have also been measured for the reactions [Formula: see text], where B is 2,2′-bipyridyl or 1,10-phenanthroline. These constants were obtained by pH measurements at 25 °C and an ionic strength of 0.60. The results are compared with those for similar systems, especially as regards the tendency to form ternary mixed complexes of the type MAB.The rates of decarboxylation of the various MA and MAB species have been measured. The resulting rate constants follow the Irving–Williams order for stability constants, except that in both MAB species the cobalt compound decomposed slightly faster than the nickel compound. The aromatic base, which had been found earlier to have very little effect in copper complexes, increased the rate constants appreciably with other metals, especially with manganese and zinc. Usually 1,10-phenanthroline has a larger effect than 2,2′-bipyridyl. Some possible explanations of the results are considered.
A Low Temperature Infrared Study of Self-association in Thiols
Authors: Alencastro R. Bicca de , Sandorfy C.
Published: May 2006

The infrared spectra of several aliphatic thiols and of benzenethiol were measured between 2400 and 2700 cm−1, and 4800 and 5300 cm−1 in a 1:1 mixture of CCl3F and C2F4Br2, at temperatures ranging from 20 to −190 °C. Dimerization takes place at low temperatures and more highly associated species also appear. Free S—H groups are present in the solutions as well as in the pure liquids, even at the lowest temperatures. The association is of the [Formula: see text] type in aliphatic thiols; both [Formula: see text] and [Formula: see text] bonds are found in the case of benzenethiol and α-toluenethiol. Hydrogen bonding has little effect on the anharmonicity of the S—H stretching vibration.
Photolysis of Ethyl Diazomalonanilate in Acetonitrile
Authors: Buu Nguyen Thanh , Edward J. T.
Published: May 2006

Photolysis of ethyl diazoacetate and of ethyl diazomalonate in acetonitrile gave oxazoles. Photolysis of ethyl diazoacetate in the presence of benzophenone gave an oxazoline incorporating the elements of carbethoxymethylene. benzophenone, and acetonitrile. Photolysis of ethyl diazomalonanilate gave 5-ethoxy-2-methyl-4-phenylcarbamoyloxazole, 5-ethoxy-3-methyl-4-phenylcarbamoylisoxazole, and ethyl α-hydroxymalonanilate. With 2537 Å wavelength radiation the oxazole was formed predominantly; on the other hand, with benzophenone-sensitization, the isoxazole was formed (among other products) but no oxazole. The oxazole was isomerized to the isoxazole when irradiated in the presence of a sensitizer, while the isoxazole was isomerized to the oxazole when irradiated with radiation of 2537 Å wavelength. A tentative mechanism is advanced to explain formation of the different products.
Oxidation of p-Dimethylaminobenzaldehyde Semicarbazone. Novel Conversion of an Aromatic Aldehyde to an Aroyl Cyanide
Authors: Knittel Peter , Warkentin John
Published: May 2006

Oxidation of the semicarbazone of p-dimethylaminobenzaldehyde with lead tetraacetate affords p-dimethylaminobenzoyl cyanide. Probable intermediates are an iminooxadiazoline and an iminooxirane.
The Photocyclization of Aromatic Thioketones
Authors: Lapouyade R. , Mayo P. De
Published: May 2006

Certain aromatic thioketones, having an adjacent vacant peri position to the thiobenzoyl group cyclize on irradiation. This rearrangement, unknown in the ketonic series, leads to thiophane derivatives.
Reduction of α-D-Hexopyranosulosides
Authors: Lemieux R. U. , James K. , Nagabhushan T. L.
Published: May 2006

Reduction of isopropyl tri-O-acetyl-α-D-arabino-hexopyranosuloside with sodium borohydride or diborane leads almost exclusively to the gluco-configuration. Catalytic reductions, on the other hand, provide an epimeric mixture with the manno-configuration predominating in ratios of about 2:1. The reduction of isopropyl tri-O-acetyl-α-D-lyxo-hexopyranosuloside with either sodium borohydride or diborane is less stereoselective than in the case of the arabino-isomer and leads to compounds of the galacto-and talo-configurations in the ratio of 3:2. The latter is formed highly stereoselectively when the lyxosuloside derivative is hydrogenated catalytically.2-O-(α-D-Mannopyranosyl)-glycerol and the gluco-isomer are synthesized.
Kinetics of Reactions of Hexa(dimethylsulfoxide)nickel(II) Ion with Dithiocarbamate Ligands
Authors: Scharfe R. R. , Sastri V. S. , Chakrabarti C. L. , Langford C. H.
Published: May 2006

The kinetics of complex formation Ni(DMSO)62+ with dithiocarbamate ligands at 25 °C in DMSO is reported. The reactions display the apparent "anomaly" in the direction of slow reaction reported earlier for some other complex formation reactions of Ni(DMSO)62+ in DMSO.
Determination of the Rates of Hydrogen Atom Reaction with NO by a Modulation Technique
Authors: Atkinson R. , Cvetanović R. J.
Published: May 2006

A modulation technique has been used to determine from phase shift measurements the absolute values of the rate constants and the Arrhenius parameters of the reaction of hydrogen atoms with nitric oxide.
A Mössbauer Study of the Iron Tetracarbonyl Halides
Authors: Vasudev P. , Jones C. H. W.
Published: May 2006

The 57Fe Mössbauer spectra of the cis-Fe(CO)4X2 compounds (X = Cl, Br, I) have been measured and the values of δ (~0.3 mm s−1) and Δ (~0.3 mm s−1) found to differ significantly from those previously reported for Fe(CO)4I2. The Δ values are analyzed in terms of p.q.s. values of the ligands.The photolysis of cyclohexane solutions of Fe(CO)4I2 was studied and no evidence was found in the 57Fe Mössbauer spectra of frozen samples for the previously proposed formation of trans-Fe(CO)4I2.The 129I Mössbauer absorption spectrum of cis-Fe(CO)4129I2 is reported and the parameters found to be δ = +0.11 ± 0.02 mm s−1, e2qQ = −980 ± 10 Mc s−1, η = 0.00 ± 0.02. The parameters are interpreted as evidence of ca. 5% 5s character on the iodine in the Fe—I bond.
Cobalt(II) Mercury Tetrathiocyanate Complexes with Lewis Bases
Authors: Makhija R. , Pazdernik L. , Rivest R.
Published: May 2006

A new series of octahedral cobalt(II) complexes are formed when CoX2(X = Cl, Br, I, SCN) reacts with Hg(SCN)2 in the presence of Lewis bases. These complexes of stoichiometry CoHg(SCN)4•2L (L = THF, dioxane, pyridine, aniline) are pink to violet solids which slowly decompose to the blue crystalline solid, CoHg(SCN)4, the stable magnetic susceptibility standard. On further reaction of CoHg(SCN)4•2THF with mono-, bi-, and polydentate ligands in dry ethanol, complexes of the following types are obtained: CoHg(SCN)4•2L (L = PΦ3), CoHg(SCN)4•2LL (LL = trien), CoHg(SCN)4•3LL (LL = en, bipy), and CoHg(SCN)4•4LL (LL = phen). The stoichiometry of these were determined by elemental analysis. Possible structures of these are discussed with the help of mid and far infrared, visible, and ultraviolet spectroscopy, magnetic susceptibility, and X-ray powder diffraction. Some new i.r. bands like Co—P, Co—N, and Hg—S are assigned in the low region.
Nuclear Magnetic Resonance Studies of Solute–Solvent Interactions. Improved Methods of Proton Chemical Shift Determinations for Completely Associated and Unassociated Solutes
Authors: Klinck R. E.
Published: May 2006

Previous data for the temperature dependence of the proton chemical shifts of two para-substituted benzaldehydes in toluene solution are re-investigated using improved methods for obtaining the proton chemical shifts in the associated and unassociated solutes. The calculations provide ΔH and ΔS values of −1.13 ± 0.07 kcal/mol and −4.0 ± 0.3 e.u., respectively. Attempts to determine the solute–solvent ratio gave inconclusive results.
A Comparison of the Conformations of Uridine, β-Pseudouridine, and Dihydrouridine in Dimethyl Sulfoxide and Water. A 1H Nuclear Magnetic Resonance Study
Authors: Deslauriers Roxanne , Smith Ian C. P.
Published: May 2006

The 1H n.m.r. spectra of the nucleosides uridine (U), dihydrouridine (D), and β-pseudouridine (β-ψ) in deuterated dimethyl sulfoxide (DMSO-d6) have been analyzed and the results compared with those obtained from analyses of spectra taken in deuterated water (D2O). The conformations of the ribose rings in DMSO-d6 and D2O solutions are similar. The conformation about the exocyclic C4′—C5′ bond shows a greater preference for the gauche–gauche rotamer in DOMO-d6 than in D2O. No changes in the sugar–base torsion angle were detectable in the spectra taken with the two solvents. The resonances of the sugar ring hydroxyl protons were assigned and the spin–spin couplings measured. In the three nucleosides studied the hydroxyl groups are rotating rapidly with only slight preferences for the particular rotamers. When preferences are manifest, they are for the gauche rotamers at 2′ and 3′, and the symmetrical gauche–gauche rotamer at 5′.
The Barrier to Rotation in 2,2′-iminobis (acetamidoxime) and its Nickel(II) and Zinc(II) Complexes
Authors: Cramer Roger E. , DeRyke Robert
Published: May 2006

The free energy of activation at the coalescence temperature was measured for the rotational barrier about the amide bond in 2,2′-iminobis(acetamidoxime) (IBO) and its Ni(II) and Zn(II) complexes. The barrier is 10.5 ± 0.3 kcal/mol and increases by about 1 kcal/mol upon coordination of Ni(II) and Zn(II). By means of INDO molecular orbital calculations it is shown that the amide proton trans to the donor nitrogen experiences the largest isotropic shift in Ni(IBO)2(NO3)2 and that the major portion of spin delocalization takes place through the oxime nitrogen σ donor orbital, which is not the highest filled orbital of the ligand.
The Beckmann Rearrangement on Ketoximes Initiated by Hexamethylphosphoric Triamide
Authors: Monson Richard S. , Broline Bruce M.
Published: May 2006

Ketoximes are found to undergo the Beckmann rearrangement in hexamethylphosphoric triamide at 225–240°, affording the corresponding amides in good yield.
A Field Ion Investigation of Oxygen on Tungsten
Authors: Shigeishi R. A.
Published: May 2006

The adsorption of oxygen on tungsten was investigated with a field ion microscope. Two experimental procedures were followed. In the first, a tungsten tip previously annealed to 973 or 1173 °K was held at 78 °K while exposed to oxygen. Coverages ranged from less than a monolayer to saturation. After the ambient oxygen was removed, the tip was heated to the annealing temperature. In the second, oxygen adsorption occurred on a hot tip held at 973 °K. Estimated coverages were significantly less than a monolayer.Results reveal a dramatic difference in the extent of surface diffusion, rearrangement, disruption, and oxygen penetration for the two procedures, the latter producing more extensive effects. Possible explanations for these differences are considered.
Crystal Structure of α-Zn2V2O7
Authors: Gopal Ramanathan , Calvo Crispin
Published: May 2006

α-Zn2V2O7 is monoclinic with lattice parameters a = 7.429(5), b = 8.340(3), c = 10.098(3) Å, β = 111.37(5)°, Z = 4 and space group C2/c. The structure was refined using a full matrix least-squares with 1034 reflections measured with a quarter-circle General Electric automatic X-ray diffractometer to a final R value of 0.066. The anion consists of a pair of VO4 tetrahedra sharing an oxygen atom which lies on a two-fold axis. The bridging V—O bond length is 1.775(4) Å while the three independent terminal ones are 1.728(4), 1.704(7), and 1.658(8) Å long. These bond lengths are consistent with the charge character around the individual oxygen atoms. The Zn ions are coordinated to five oxygen atoms with Zn—O bonds ranging from 1.973 to 2.088°Å. The structure is similar to that of α-CU2P2O7 and transforms to the thortvietite structure at about 615 °C.