bluuebunny/crossref_metadata_2025 huggingface dataset:
Nickel(II) complexes with substituted ureas
Authors: Bailey R. A. , Feins I. R. , Peterson T. R.
Published: May 2006

A number of nickel(II) complexes with methyl-, n-butyl-, phenyl-, and N,N′dimethylurea ligands were prepared with a variety of anions. All exhibited octahedral coordination geometry. Of the anions, only NCS− was in the coordination sphere. Infrared spectral studies indicate coordination of the ligands through oxygen.
Kinetics of the thermal reactions of ethylene
Authors: Simon M. , Back M. H.
Published: May 2006

Measurements of the yields of products and the decrease in pressure as a function of time have shown the relation between the mechanisms for the thermal reactions of ethylene proposed in two separate studies, which jointly cover the range 776–924 °K and 10–600 Torr. Specifically, the measurements relate the polymerization and decomposition processes and show the dependence on temperature and pressure of the reactions proposed.
Electric moments, sulfur bonding, and conformations of substituted thiochloroformate esters in benzene solutions
Authors: Queen A. , Nour T. A. , Bock E.
Published: May 2006

The dipole moments of a series of aryl and alkyl thiochloroformate esters have been determined in benzene solution at 25 °C and compared with the corresponding values for chloroformate and fluoroformate esters. The results have been interpreted in terms of conjugative and hyperconjugative electron release by the hydrocarbon group to the d-orbitals of the sulfur atom in the thio compounds. Vector model, bond moment calculations indicate that, as in the cases of the chloroformate and fluoroformate esters, the preferred conformations of the thiochloroformates are those in which the hydrocarbon group and the halogen atom are cis to each other.
Aromatic oxidation by cobaltic acetate in acetic acid
Authors: Sakota Koichiro , Kamiya Yoshio , Ohta Nobuto
Published: May 2006

A detailed kinetic study of oxidation of toluene and its derivatives by cobaltic acetate in 95 vol% acetic acid is reported. The reaction was found to be profoundly affected by a steric factor and rather insensitive to the C—H bond energy. The order of reactivities of various alkylbenzenes is quite reversal to that of hydrogen abstraction reactions. The reaction was of first-order with respect to toluene, of second-order with respect to cobaltic ion and of inverse first-order with respect to cobaltous ion. The oxidation by cobaltic ion seems to proceed via an initial reversible electron transfer from toluene to cobaltic ion, yielding [Formula: see text] which is oxidized into benzyl acetate by another cobaltic ion. The apparent activation energy for toluene was found to be 25.3 kcal mole−1, and the same activation energy was found for ethylbenzene, cumene, diphenylmethane, and triphenylmethane.
Alkaloids of Lycopodiumlucidulum Michx. Structure and properties of alkaloid L.23
Authors: Ayer W. A. , Altenkirk B. , Burnell R. H. , Moinas M.
Published: May 2006

The minor alkaloids present among the strong bases of Lycopodiumlucidulum have been reinvestigated. Manske and Marion's alkaloid L.23 has been shown to be epimeric with lycodoline at C-12 and the nitrogen. A correlation between the two alkaloids has been achieved. The presence of a σ-coupled p interaction in the ultraviolet spectrum of lycopodine, lycodoline, and related compounds is described. A Cotton effect due to this chromophore has been detected by means of circular dichroism. The optical rotatory dispersion and circular dichroic properties of lycopodine, 12-epilycopodine, lycodoline, and alkaloid L.23 are discussed in terms of the absolute configuration assigned to these alkaloids.
Coordination compounds of methyl gallium hydrides
Authors: Storr A. , Wiebe V. G.
Published: May 2006

Although the organo hydride derivatives of boron and aluminium are well characterized, little work has been reported on the corresponding gallium systems. The present study was initiated to determine the relative stabilities of organo gallium hydride derivatives as compared to the stabilities of the corresponding compounds of boron and aluminium. Various preparative routes in this new class of gallium compounds have been investigated. These include the use of organo mercury and organo lithium reagents in reactions with gallium hydride compounds and their halogen substituted derivatives, and also equlibration reactions between gallium hydride and organo gallium compounds. Both infrared and proton magnetic resonance spectroscopy techniques have been used extensively in following the progress of these reactions and in the characterization of the products.
γ-Radiolysis of disulfides in aqueous solution. III. L-Cysteine-D-penicillamine mixed disulfide
Authors: Purdie J. W.
Published: May 2006

L-Cysteine-D-penicillamine mixed disulfide (CySSPen) was irradiated in aerated and deaerated aqueous solutions with 60Co γ-rays. G values were determined for all products identified after exposure to 10 000 rads. The major products were the sulfinic and sulfonic acids (CySO2H, CySO3H, and PenSO2H), the sulfhydryl derivatives (CySH and PenSH), symmetrical disulfides (CySSCy and PenSSPen), three trisulfides (CySSSCy, CySSSPen, and PenSSSPen), and ammonia. Each half of the disulfide behaved in exactly the same way as the corresponding symmetrical disulfide. Products from the CyS— part of the disulfide were dose rate dependent while products from the PenS— part were independent of dose rate. The reactions proposed for the symmetrical disulfides were adequate to explain radiolysis of the unsymmetrical disulfide.Radiolysis of a mixture of cystine and penicillamine disulfide was examined for comparison with the unsymmetrical disulfide and was found to give very similar results. It was concluded that the free radicals produced from the water attack each half at approximately equal rates.
The infrared absorption spectra of thiosemicarbazide and related compounds: NH2 and NH vibrations
Authors: Wiles D. M. , Suprunchuk T.
Published: May 2006

In the infrared absorption spectra of thiosemicarbazide (I), aldehyde thiosemicarbazones (II), and N-methyl derivatives of these compounds, the following assignments are proposed: νa(NdH2) absorbs in the vicinity of 3400 cm−1; NaH2 vibrations are observed in the region of 1630 cm−1; there is a significant contribution from ν(NbH) at or near 3170 cm−1. These conclusions probably apply to other thioamides and amides having related structures.
Metabolites of pathogenic fungi. VII. On the structure and stereochemistry of xanthomegnin, vioxanthin, and viopurpurin, pigments from Trichophyton violaceum
Authors: Ng A. S. , Just G. , Blank F.
Published: May 2006

Recently, we proposed structure 1 for xanthomegnin (1) and tentatively assigned structures 2 and 3 for vioxanthin and viopurpurin respectively (2). We should now like to present evidence which confirms the structure of vioxanthin (2), adds weight to the structure proposed for viopurpurin, and which defines the stereochemistry of the lactone ring in 1 and 3.
Coupling of allylic halides promoted by iron metal dispersed in dimethyl formamide
Authors: Hall David W. , Hurley Jr Edward
Published: May 2006

The coupling reaction of allylic halides to produce non-conjugated dienes was investigated. It was found that iron powder could be utilized, without any special pretreatment, to promote the coupling reaction when a dipolar aprotic solvent was employed as the reaction medium.Effects of variables such as the nature of the halogen atom in the reactive position of the substrate, substituents on the substrate, presence or absence of organic or inorganic halide catalysts, and solvent type were explored briefly.Non-conjugated dienes can be prepared in yields which exceed 90% in the more favorable cases. The present procedure avoids many of the difficulties inherent in such previous methods as the Grignard reaction or the nickel carbonyl-promoted reaction.
Synthesis of 2-acetamido-2-deoxy-D-gulose, 2-acetamido-2-deoxy-D-idose, and 2-deoxy-D-xylo-hexose from 3,4,5,6-tetraacetoxy-D-xylo-1-nitro-1-hexene
Authors: Perry M. B. , Webb Ann C.
Published: May 2006

3,4,5,6-Tetraacetoxy-D-xylo-1-nitro-1-hexene with methanolic ammonia afforded a mixture of 2-acetamido-1,2-dideoxy-1-nitro-D-gulitol and 2-acetamido-1,2-dideoxy-1-nitro-D-iditol which were converted via a Nef reaction to 2-acetamido-2-deoxy-D-gulose and 2-acetamido-2-deoxy-D-idose.Reduction of 3,4,5,6-tetraacetoxy-D-xylo-1-nitro-1-hexene afforded 3,4,5,6-tetra-O-acetyl-1,2-dideoxy-1-nitro-D-xylo-hexitol which was converted via the Nef reaction to 2-deoxy-D-xylo-hexose.
A mechanistic study of the base-catalyzed methanolysis and hydrolysis of the hydrogen phthalate ester of 4-bromo-4′-nitrobenzhydrol
Authors: Rutherford K. G. , Mamer O. A. , Tang B. K.
Published: May 2006

The hydrogen phthalate ester of 4-bromo-4′-nitrobenzhydrol has been subjected to base-catalyzed methanolysis and hydrolysis. In both cases the BAC2 mechanism has been observed. There is no evidence of ortho-carboxylate anion participation (BAC1 mechanism). The results have been substantiated by kinetics, stereochemistry, and 18O isotope studies.
Potentiostatic study of ferrous–ferric kinetics at bright gold and platinum electrodes
Authors: Barnartt Sidney
Published: May 2006

Ferrous–ferric reaction kinetics on gold in chloride and sulfate solutions, and on platinum in a sulfate solution, were studied potentiostatically. The data illustrate the importance of precise potential control and of automatic ohmic compensation. The standard exchange current density is 0.38/f A cm−2 (where f is the mean ionic activity coefficient) on platinum; it is an order of magnitude larger on gold.
Co(II) complexes with 2-pyrrolidinone
Authors: Bohunovsky O. , Jain S. C. , Rivest R.
Published: May 2006

For the known complexes CoL3X2 (X = Cl, Br, and L = 2-pyrrolidinone) a more detailed infrared study was made. Together with the electronic spectra this study indicates dissociation of CoL2X3 into CoL2X2 + L in chloroform and acetone solution. The conductivity measurements and the molecular weight determinations also support dissociation. The probable structure in the solid state is [CoL3X]X. The new 1:1 compound of 2-pyrrolidinone with boron trichloride was prepared to confirm the conclusions made from the infrared spectra of the cobalt complexes.
Reaction of atomic hydrogen with tetrafluoroethene
Authors: Teng Lei , Jones W. E.
Published: May 2006

Hydrogen atoms, generated in a Wood's electric discharge tube, were allowed to react with tetrafluoroethene. The products of the reaction were found to be HF, C2F3H, C2H2, C2F2H2, C2F4H2, C2FH3, C2H4, and CHF3. The formation of the products with the exception of HF was studied quantitatively from 30–330 °C.
Inelastic collisions at low energies
Authors: Dalgarno A.
Published: May 2006

A summary is presented of the processes by which low energy electrons lose energy in moving through the atmosphere and estimates are given of the cross sections and energy loss rates. The mechanisms by which thermal electrons cool are described and the cooling efficiencies are listed.
Comments and Summary
Authors: Mcelroy Michael B.
Published: May 2006

not available
Comments and Summary
Authors: Nier A. O. C.
Published: May 2006

not available
A revised structure for the so-called "diadrenaline ether"
Authors: Forrest Janet E. , Kašpárek S. , Heacock R. A. , Forrest T. P.
Published: May 2006

The correct structure for the product, obtained by the action of 20% HCl on adrenaline (1) and previously described as diadrenaline ether (2), has been shown to be 6-(3′,4′-dihydroxy-α-methyl-aminomethylbenzyl)adrenaline (3). The trivial name adrepine is suggested for the base (3).
Studies on metal hydroxy compounds. VII. Thermal analyses of copper derivatives
Authors: Ramamurthy P. , Secco E. A.
Published: May 2006

Copper basic halide compounds have been studied by thermogravimetric and differential thermal analyses. This study reveals the general pattern of thermal stability observed for cadmium and zinc basic halides.The initial mode of decomposition varied within the copper group. The iodides, bromides, and chlorides all decomposed via dehydroxylation and in this way resembled the Cd and Zn basic halides. The copper basic fluorides, on the other hand, decomposed by simultaneous dehydroxylation and dehydrofluorination which is in distinct contrast to the Cd and Zn basic fluorides.
Electron paramagnetic resonance spectroscopic study of nitroxide radicals formed from oximes
Authors: Smith P. , Fox W. M.
Published: May 2006

The addition of hydroxyl radicals to each of the oximes, acetaldoxime, acetoxime, and 2,3-butanedione monoxime, has been studied by mixing titanous chloride, hydrogen peroxide, and the oxime in an aqueous continuous-flow system. In each case a β-hydroxy nitroxide (functional structure [Formula: see text] is formed. In confirmation of these results, amino and hydroxymethyl radicals were added to the oximes using similar procedures to give in each case the radicals of functional structure [Formula: see text] and [Formula: see text], respectively. Attempts to add methyl radicals, prepared by the reaction between titanous chloride and t-butyl hydroperoxide, to these oximes gave no observable products save the methyl radicals. However, use of titanous chloride and peracetic acid gave results consistent with the addition of hydroxyl radicals. The addition of hydroxyl radicals to the oxime-O-methyl ethers of acetaldehyde and acetone gave radicals of functional structure [Formula: see text][Formula: see text] which have not previously been identified unambiguously. On the assumption that |QN| = |QHNH| = 23 G in all these radicals, ρNπ has been calculated and used to obtain a value for [Formula: see text] of ca. 11 G which is within the range of other estimates in the literature.
Some substituted urea and thiourea complexes of Co(II), Mn(II), and Cr(III)
Authors: Askalani Pakinam , Bailey R. A.
Published: May 2006

Complexes of Co(II), Mn(II), and Cr(III) with N-butylurea, N-methylthiourea, and N,N′-dimethylthiourea, and Cl−, Br−, NO3−, and ClO4− anions were prepared and characterized using infrared and visible spectroscopy, and magnetic susceptibility. The urea is bonded through oxygen, and the thioureas through sulfur in all cases. The Co–N-butylurea compounds are octahedral, mostly with CoL6X2 stoichiometries, but some compounds involving coordinated anions and possibly bridging butylurea ligands were found. The Co–thioureas are tetrahedral. Octahedral Cr(III) compounds of the type CrL3X3 and CrL6(ClO4)3 were prepared, and the CrS6 chromophore characterized. Mn(II)–butylureas are octahedral, while the thioureas show MnL6X2 and MnL4X2 stoichiometries. X-ray diffraction established some of the latter to be isostructural with the analogous tetrahedral Co(II) compounds. Ligand field parameters Dq and B have been evaluated for the Co(II) and Cr(III) compounds.
Reaction of chromyl chloride with donor molecules
Authors: Makhija R. C. , Stairs R. A.
Published: May 2006

Reaction of chromyl chloride with various donor molecules led to solid products of compositions CrO2Cl2.2D (D = acetone or dimethylsulfoxide), 2CrO2Cl2.3D (D = tetrahydrofuran, 1,4-dioxan, or 4-picoline), CrO2Cl2.D (D = diethyl ether, triphenylphosphine, or triphenylarsine), and 2CrO2Cl2.(C6H5)3N. Acetonitrile failed to react. Infrared and ultraviolet spectra, X-ray diffraction and magnetic measurements, and the organic products obtained on hydrolysis were interpreted as showing that none of these complexes are Lewis adducts of chromyl chloride, but that all contain chromium(IV).
Studies on metal hydroxy compounds. VIII. Heats of decomposition of twelve copper halide derivatives
Authors: Ramamurthy P. , Secco E. A.
Published: May 2006

not available
Formation of 2,3-epoxyperfluoropropionylfluoride from the mercury photosensitized oxidation of 1,3-perfluorobutadiene
Authors: Stuckey Wayne , Heicklen Julian , Knight Vester
Published: May 2006

The mercury photosensitized oxidation of 1,3-C4F6 gives nearly equal amounts of CF2O and a new compound 2,3-epoxyperfluoropropionylfluoride and smaller amounts of c-C3F4. The infrared (i.r.) and mass spectra of 2,3-epoxyperfluoropropionylfluoride are presented.
Sur l'acylation de l'éthyl-1 cyclohexène en présence de chlorure stannique
Authors: Allard Jean , Dufort Normand
Published: May 2006

not available
Hydration of the potassium ion in the gas phase: enthalpies and entropies of hydration reactions
Authors: Searles S. K. , Kebarle P.
Published: May 2006

The thermodynamic constants ΔH0n−1,n, ΔG0n−1,n, and ΔS0n−1,n for the reaction [n − 1, n]: K+(H2O)n−1 + H2O = K+(H2O)n proceeding in the gas phase were measured for n = 1 to n = 6. The equilibria were studied in a reaction chamber containing water vapor at pressures from 0.3 to 6 Torr and at temperatures from −11 to 390 °C. The potassium ions were produced by thermionic emission in a filament chamber and then were equilibrated with the water vapor in the reaction chamber. The relative ionic concentrations were detected with a mass spectrometer. The experimental ΔH0n−1,n values are compared with potential energy differences for the reactions [n − 1, n] based on simple electrostatic model calculations. The electrostatic calculations produce values in fair agreement with the experimental results. The ΔS00,1 calculated on basis of statistical mechanics and energies obtained with the electrostatic model is in very good agreement with the experimental result.
Structure of the second coordination sphere of transition metal complexes. I. Co(II) complexes with aniline and pyridine
Authors: Eaton D. R.
Published: May 2006

Geometric and thermodynamic parameters relating to the structure of labile second sphere coordination complexes formed between Co(II) chelates and aniline and pyridine molecules in carbon tetrachloride solution have been obtained. The effect of dipolar interactions, resulting from the magnetic anisotropy of the cobalt chelate, on the nuclear magnetic resonance spectra of the complexing molecules has been utilized for this purpose. Both aniline and pyridine show a preferred direction of approach perpendicular to the three fold symmetry axis of the cobalt compound used. In both cases the preferred intermolecular separation corresponds closely to that expected for a second coordination sphere ligand. The preferred orientation of the aniline molecule places the amino group adjacent to the cobalt complex and the pyridine is oriented with the γ hydrogen closest to the chelate. Enthalpy changes of −2.4 ± 0.2 kcal and −2.9 ± 0.3 kcal have been obtained for the formation of the aniline and pyridine complexes, respectively. The effect of averaging tumbling and translational motions on the dipolar shifts has been considered. The meaning of the parameters derived is discussed in the light of the very labile nature of the second coordination sphere complexes. The relevance of these results to the mechanisms of ligand substitution processes and homogeneous catalysis is emphasized.
The use of a saturation narrowed nuclear magnetic resonance spectrum to observe phase transitions in lithium stearate
Authors: Janzen W. R. , Dunell B. A.
Published: May 2006

The phase transitions in solid lithium stearate have been observed using saturation narrowed spectra, whose high signal-to-noise ratio is advantageous particularly in cases where unfavorable packing factor for the sample or long T1 makes the normal unsaturated absorption spectrum difficult to obtain. The saturation narrowed spectra are compared with unsaturated absorption spectra of lithium stearate and are discussed in terms of Provotorov's theory of saturation.
Nuclear charge dispersion in the fission of 233U by protons of medium energy
Authors: Tomita I. , Yaffe L.
Published: May 2006

Independent yields and excitation functions have been determined for the formation of cesium isotopes with masses 129 ≤ A ≤ 138 in the fission of 233U with protons of energies between 20 and 80 MeV. The energies at which the various excitation functions reach their maxima have been compared with those obtained for the same isotopes from fissioning systems with targets of different neutron-to-proton (N/Z) ratios. The neutron-deficient species have a higher probability of being produced at lower energies from targets with lower N/Z ratios. Charge dispersion curves have been obtained and these show the familiar broadening and displacement of Zp, the most probable charge, towards stability with increase in bombardment energy. Values of ZA – Zp have been compared with those obtained from other fissioning systems, and predictions made for values of Zp in the fission of systems yet unstudied, e.g. 235U and 239Pu. In addition Zp values were calculated for 233U fission, assuming compound nucleus formation up to a proton energy of 50 MeV, assuming pre- and post-fission neutron evaporation on the equal charge displacement and unchanged charge division postulates. Experimental values were found to lie between the two predictions.
Preparation and properties of σ-bonded picryl platinum compounds
Authors: Norris A. R. , Baird M. C.
Published: May 2006

The compounds cis-PtCl(pic)(EPh3)2 (pic = 2,4,6-trinitrophenyl; E = P, As) have been prepared by the oxidative addition of picryl chloride to the zero valent platinum compounds, Pt(PPh3)3 and Pt(AsPh3)4. Both new compounds react with cyanide ion to give intensely colored red complexes.
Complexing between palladium(II) halides and p-NOC6H4NMe2 and p-NOC6H4NEt2
Authors: Batten I. , Johnson K. E.
Published: May 2006

The complexes PdL2X2 (L = p-nitrosodimethylaniline, p-nitrosodiethylaniline; X = Cl, Br, I) have been prepared. The principal absorption band in the visible spectra of the complexes has been identified as a π–π* transition centered primarily on the ligands on the basis of its high oscillator strength, the similarity of the latter to that of the free organic ligand, and the insensitivity of the band position to the nature of the halide. Infrared data indicate that palladium is bonded through the NO group.
Radiation induced dimerization of 2- and 3-methyl-2-pentenes
Authors: Brash J. L. , Golub M. A.
Published: May 2006

The dimers formed in the electron irradiation of 2- and 3-methyl-2-pentenes were found to have average unsaturations of 1.53 and 1.35 double bonds per dimer molecule, respectively, and were formed with G values of 2.6 and 1.8, respectively. The dimers were considered to form by both ion-molecule and radical mechanisms.
Temperature jump kinetics of the binding of imidazole to ferriprotoporphyrin IX
Authors: Hasinoff Brian B. , Dunford H. Brian , Horne Dale G.
Published: May 2006

The kinetics of binding of imidazole to ferriprotoporphyrin IX (hemin) in aqueous ethanol has been studied at 25° using the temperature jump technique. The reaction was studied quantitatively as a function of acid concentration using the pH scale developed by Bates et al. for mixed solvent systems. The results can be explained by a mechanism in which the imidazolium ion binds to hemin with a specific rate constant of (4 ± 2) × 106 M−1 s−1 and imidazole binds with a rate constant of (3 ± 0.3) × 104 M−1 s−1. The dissociation constant for the imidazolium ion was determined by acid–base titration to be 1.8 × 10−7 M, and a dissociation constant for the hemin of 2.3 × 10−7 M was determined by spectrophotometric titration in a solvent containing 44.5 weight % of ethanol. The latter dissociation involves the proton on a solvent ligand.
Separation and identification of methyl ethers of D-glucose and D-glucitol by gas–liquid chromatography
Authors: Jones H. G. , Jones J. K. N.
Published: May 2006

The separation by gas–liquid chromatography of the methyl ethers of D-glucose and of D-glucitol is described.
A study of potential cyclopropyl–silver ion complex formation
Authors: Menon B. C. , Pincock Richard E.
Published: May 2006

The relative abilities of some cyclopropyl derivatives of norbornene and of norbornadiene to form water soluble complexes with 1 M silver nitrate at 25° were determined. Equilibrium constants, Keq, for the reaction[Formula: see text]were in the order[Formula: see text]Quadricyclene (tetracyclo[3.2.0.02,704,6]heptane) is rapidly isomerized to norbornadiene in the presence of silver ion under the equilibration conditions. The relative Keq values are interpretable in terms of steric and inductive effects of cyclopropyl groups on olefin – silver ion complex formation and they give no evidence of a stabilizing cyclopropyl – silver ion interaction.
Electrochemical studies of lanthanum and lanthanum–zinc alloys in fused LiCl–KCl eutectic
Authors: Lesourd Jean-Baptiste P. F. , Plambeck James A.
Published: May 2006

The electromotive force of cells of the type La(s)/LiCl–KCl (eutectic) + LaCl3/(La + Zn, saturated liquid alloy) has been measured over the temperature range 450–600 °C. Thermodynamic functions for the limiting lanthanum–zinc solid intermetallic compound existing in this range are: ΔGf0, −58.8 kcal/mole, ΔSf0, −53 cal/deg mole, and ΔHf0, −97 kcal/mole at 450 °C. The standard potential (mole fraction scale) of the La(III)/La(0) electrode is −2.883 V with respect to the Pt(II)/Pt reference electrode at 450 °C. The significance of these measurements for the electrochemical separation of lanthanum and uranium is discussed.
Kinetic solvent isotope effect, solvent reorganization, and the SN1–SN2 mechanism
Authors: Treindl L. , Robertson R. E. , Sugamori S. E.
Published: May 2006

The temperature dependence of the rates of solvolysis have been determined in D2O for t-butyl chloride, 2,2-dibromopropane, 2-bromo-2-chloropropane, and 2-chloro-2-methyl propyl methyl ether, and corresponding values of ΔH≠, ΔS≠, and ΔCp≠ are derived. Values of ΔH≠ and ΔS≠ from the solvolysis of seven other halides and two benzenesulfonates have been estimated from rate determinations at two temperatures in D2O.A comparison of these values with terms from corresponding experiments in H2O provides values of δIΔG≠, δIΔH≠, and δIΔS≠ characterizing the kinetic solvent isotope effect.While δIΔG≠ appears to have about the same value for a wide range of halides of different structure irrespective of the probable mechanism of reaction, systematic differences in δIΔH≠ and δIΔS≠ differentiate those reacting by an SN2 mechanism from those reacting by an SN1 mechanism. This difference is in the direction suggesting a loosening of solvent structure in the activation process in agreement with indications obtained from the corresponding values of the heat capacity of activation.
Deamination of two steroidal α-aminoketones
Authors: Edwards O. E. , Sano T.
Published: May 2006

The two aminoketones 12α-amino-3α,20β-diacetoxy-11-keto-5β-pregnane and 9α-amino-3β,20β-diacetoxy-11-keto-5α-pregnane were prepared. Deamination of the former could be controlled to give either 12-methyl-18-norpregnane derivatives or C-nor-D-homo (12,14-cyclo-13,14-secopregnane)derivatives. Deamination of the 9α-aminoketone gave a series of 9β-methyl-19-norsteroids.
Relative rate constants for reactions of hydroxyl radicals from the reaction of Fe(II) or Ti(III) with H2O2
Authors: Armstrong W. A.
Published: May 2006

In an attempt to clarify the reactions of ferrous sulfate and titanous sulfate with hydrogen peroxide, a novel method has been developed to determine the relative rate constants for reactions of the oxidizing species generated in these systems. These species react with hydrogen peroxide to give perhydroxyl radicals which combine with titanium(IV) ions to form the relatively stable TiOO•3+ radical. This radical gives a strong electron spin resonance signal and the competition between hydrogen peroxide and a scavenger for the oxidizing species can be followed by measuring the amplitude of this signal in the presence of various concentrations of scavenger. The relative rate constants calculated in this way for both the Fe(II)–H2O2 and Ti(III)–H2O2 systems at pH 1.0 agree with those reported for the reactions of hydroxyl radicals in γ-irradiated thymine solutions. This supports the view that hydroxyl radicals are formed in these cases.Under conditions of acidity favoring the hydrolysis of Fe(II) to FeOH+ ions, hydroxyl radical scavengers do not compete with hydrogen peroxide for the precursors of the TiOO•3+ radical. It is suggested that the FeOH+ ions react with hydrogen peroxide to give a different oxidizing species, possibly the ferryl ion.Scavengers investigated were thymine, methanol, ethanol, formic acid, acetic acid, chloride ion, and several amino acids.
Absolute rate constants for hydrocarbon autoxidation. XVI. Reactions of peroxy radicals at low temperatures
Authors: Adamic K. , Howard J. A. , Ingold K. U.
Published: May 2006

The equilibrium constants for the formation of some t-alkyl tetroxides and the rate constants for irreversible decay of the tetroxides have been measured by electron spin resonance spectroscopy at low temperatures. The equilibrium constant appears to be virtually independent of the nature of the alkyl groups. It is concluded that differences in the rate of constants for chain termination by t-peroxy radicals at ambient temperatures are due chiefly to the differences in rate constants for irreversible tetroxide decomposition. The activation parameters for this reaction indicate that it occurs by one bond rather than two bond scission.
Reactions of ruthenium(III) ammine complexes. I. Competing acid hydrolysis and redox reactions of pentaammineruthenium(III) ions
Authors: Eliades T. , Harris R. O. , Reinsalu P.
Published: May 2006

A study of acid hydrolysis of acidopentaammines of ruthenium(III) shows that aquation is not the only reaction taking place. For the halopentaammines, both in the presence and absence of light, reduction occurs with the formation of ruthenium(II) and free halogen. When azide, instead of halide ion, is coordinated to the metal, ruthenium(II) nitrogen complexes can be prepared. The solid state decomposition of [Ru(trien)(N3)2]+ ion to [Ru(trien)N3N2]+ is described.
Pyrolysis of hydrocinnamic acid
Authors: Tan A. T. C. H. , Sehon A. H.
Published: May 2006

The pyrolysis of hydrocinnamic acid was investigated by the toluene-carrier technique over the temperature range 910–985 °K. The overall decomposition was first-order with respect to hydrocinnamic acid, and could be represented by reactions [1] and [2], respectively,[Formula: see text][Formula: see text]Both reactions [1] and [2] were found to be homogeneous first-order processes, and the rate constants may be represented by the following expressions[Formula: see text]The activation energy of reaction [1] is identified tentatively with D(C6H5CH2—CH2COOH).
Synthesis of L-glucurone. Conversion of D-glucose into L-glucose
Authors: Sowa Walter
Published: May 2006

L-Glucurone (2) was readily prepared on a small scale by treatment of D-glycero-D-gulo-heptono-lactone (1) with a molar equivalent of periodic acid; thin–layer chromatography was used for its isolation. On a larger scale pure crystalline L-glucurone was obtained in over 80% yield from 3,5;6,7-di-O-isopropylidene-D-glycero-D-gulo-heptonolactone (4) in two steps consisting of concomitant hydrolysis and oxidation of 4 with periodic acid followed by treatment of the intermediate oxidation product with trifluoroacetic acid. L-Glucose was prepared from L-glucurone by borohydride reduction and hydrolysis of the 1,2-O-isopropylidene derivative. Since 1 was derived from D-glucose, the result of this series of reactions was the conversion of D-glucose into its enantiomer L-glucose.
Carbohydrates in alkaline systems. I. Kinetics of the transformation and degradation of D-glucose, D-fructose, and D-mannose in 1 M sodium hydroxide at 22 °C
Authors: MacLaurin Donald J. , Green John W.
Published: May 2006

Rates of isomerization, epimerization, and degradation reactions were measured for D-glucose (1), D-fructose (2), and D-mannose (3) at 0.002 M in 1 M NaOH under N2 in the dark at 22 °C. Reaction system resolution was by column chromatography on anion resins in the borate form. Assay for 1, 2, and 3 was by continuous automated colorimetry of column effluent using orcinol/sulfuric acid as a reagent. D-Allose and D-altrose were not detected. Reaction rate constants (h−1) found: k12 0.038, k13 0.0005, k15 0.002, k21 0.036, k23 0.006, k24 0.072, k31 0.0005, k32 0.011, k36 0.002, where 4, 5, and 6 are products formed from 1, 2, or 3, respectively.
1,2:5,6-Di-O-isopropylidene-D-hexofuranoses and their 3-keto derivatives
Authors: Slessor K. N. , Tracey A. S.
Published: May 2006

The synthesis of the only unknown 1,2:5,6-di-O-isopropylidene-D-hexose, D-mannose, is reported. Its preparation involved the stereospecific borohydride reduction of the 3-keto intermediate prepared from D-altrose. An improved synthesis of the known D-talose derivative proceeded in an analogous manner from the parent ketone. The four 3-keto derivatives of the diacetone D-hexoses were prepared and their properties compared. In an attempt to explain the differences found in the ease of hydration of these materials, high resolution infrared hydrogen bonding studies were carried out on the eight hexose derivatives and the one hydrated ketone.
Proton magnetic resonance and mass spectrometric studies on derivatives of sodium 2-O-α-D-mannopyranosyl-D-glycerate and related compounds
Authors: Whyte J. N. C.
Published: May 2006

The proton magnetic resonance (p.m.r.) and mass spectra of the methyl ester pentaacetate of sodium 2-O-α-D-mannopyranosyl-D-glycerate from the red alga Rhodomela larix are compared to those of related compounds to affirm the assigned structure.
Absolute configurations of the (–)-erythro and (–)-threo-2,3-dihydroxybutyric acids
Authors: Bachelor F. W. , Miana G. A.
Published: May 2006

The absolute configurations of (–)-erythro-2,3-dihydroxybutyric acid and (–)-threo-2,3-dihydroxybutyric acid have been determined by optical rotatory dispersion and found to be 2(R), 3(R) for the erythro acid and 2(S), 3(R) for the threo acid.
Electrochemical generation of hydridopentamminerhodium(III) and its reaction with molecular oxygen
Authors: Johnston Leslie E. , Page John A.
Published: May 2006

The electrochemistry of Rh(NH3)5OH2+ has been studied in a buffered ammoniacal solution. The polarographic reduction wave at the dropping mercury electrode had E1/20 equal to −1.10 V (vs. saturated calomel electrode) in a 0.10 M NH3 – 0.10 M NH4ClO4 electrolyte, and gross Hg cathode electrolysis at −1.19 V produced a stable Rh(NH3)5H2+ hydride species. Both reductions were found to take place through a Rh(I) intermediate.The reaction of the Rh(NH3)5H2+ with molecular O2 in the ammoniacal electrolyte was also studied. The product was demonstrated to be a stable Rh(NH3)4(OH)(O2H)+ hydroperoxo species.
Infrared studies of the 1,3,5-trinitrobenzene – cyanide ion complex
Authors: Norris A. R. , Shurvell H. F.
Published: May 2006

Quantitative infrared studies have been made of the interactions of 1,3,5-trinitrobenzene and 1,3,5-trinitrobenzene-d3 with cyanide ion in chloroform, deuterochloroform, and acetonitrile. Absorption bands assignable to the 1:1 complex have been characterized and attempts made to assign the absorptions to fundamental modes of the complex.
Photocycloaddition of 1,1-diphenylethylene to 2,3-dihydropyran
Authors: Servé Paul , Rosenberg Herbert M. , Rondeau R.
Published: May 2006

1,1-Diphenylethylene reacts with 2,3-dihydropyran on photolysis to yield two allylic addition products as well as cycloaddition product. The triplet state of 1,1-diphenylethylene is implicated in these reactions. The cycloaddition reaction is stereoselective and is thought to result from bond polarization of the reactants.
Influence of Lewis acids on the Diels–Alder reaction. II. Rearrangement of 1- and 1,4-substituted diethyl 7-oxabicyclo[2•2•1]2,5-heptadiene-2,3-dicarboxylate adducts to 4- and 4,6-substituted diethyl 3-hydroxyphthalates
Authors: McCulloch A. W. , Stanovnik B. , Smith D. G. , McInnes A. G.
Published: May 2006

Direct formation of 4- or 4,6-alkyl and aryl substituted diethyl 3-hydroxyphthalates from the correspondingly substituted Diels–Alder adducts of 2- or 2,5-substituted furans and diethyl acetylenedicarboxylate is promoted by AlCl3 in CH2Cl2 at room temperature. The first adduct of 2,5-diphenylfuran to be isolated has been obtained from the same reaction at −20°. The aromatic compounds can be obtained alternatively by treating the adducts with BF3 or H2SO4: where the adducts can be prepared by conventional means this two-step procedure has resulted in greatly improved yields. Adducts of furan and furfuryl alcohol are similarly converted to substituted phenols. HCl effected conversion only in the case of adducts carrying a bridgehead aryl substituent; in all other cases HCl added to the substituted double bond. The mechanism of the adduct rearrangement is discussed.
Auto-oxidation of tetrakis-(p-dimethylaminophenyl)-ethylene
Authors: Elofson R. M. , Schulz K. F. , Sandin R. B.
Published: May 2006

Tetrakis-(p-dimethylaminophenyl)-ethylene (1) dissolved in benzene and a small amount of acetic acid is oxidized by air and in time sets to a gel. The reaction products are formaldehyde, formylated and demethylated substances, peroxides, and there is evidence for the formation of polymeric peroxides. The latter are believed to bring about the gelation. The oxidation of 1 is autocatalyzed by a complex between oxygen and 1 in the presence of acetic acid.
Influence de la structure du prépolymère sur la température de transition vitreuse de polyuréthanes réticulés
Authors: Perrault Guy
Published: May 2006

The influence of prepolymer structure on glass transition temperatures (Tg) of cross-linked polyurethanes has been studied with polysebacates from a homologous family of N-substituted bis(2-hydroxyalkyl)amines. The tertiary amine segments have made it possible to study the effect of lengthening the side chains (C1–C18) and inserting gauche interactions in the polymeric chain. The results show that in this system, adding gauche interactions has more effect on Tg than lengthening the side chains. Each time a gauche interaction is introduced in the diol segments, Tg increases by 9 °C. Comparisons with other systems are also presented.
Spin–lattice relaxation of 1,2-dichloroethane in different solvents
Authors: Bock E. , Tomchuk E.
Published: May 2006

The spin–lattice relaxation time of the 1,2-dichloroethane molecule has been determined in 6 different nonmagnetic or weakly magnetic solvents at 20 °C, viz: deuterated benzene, carbon disulfide, deuterated 1,2-dichloroethane, carbon tetrachloride, and deuterated chloroform. From the experimental results the relaxation rate in infinitely dilute solution, the so called intramolecular relaxation rate, was determined for each solvent. It was found that the observed intramolecular relaxation rate could be successfully interpreted as arising solely from a dipole–dipole relaxation mechanism. It was further found that the individual differences in the value of the intramolecular spin–lattice relaxation rate of the 1,2-dichloroethane molecule in different solvents could be accounted for in terms of weak complex formation between the solute and solvent molecules.
Studies on complex compounds. VI. Coordination compounds of copper and biologically active cyclohexylamine derivatives
Authors: Misra C. H. , Parmar Surendra S. , Barthwal J. P.
Published: May 2006

Five complexes of copper(II) chloride and different cyclohexylamine derivatives were synthesized, the copper:ligand ratios are 1:2. These complexes were characterized by analyses, infrared (700–3500 cm−1) and visible spectra, and conductance. The results have indicated participation of nitrogen atom adjacent to the cyclohexyl ring in coordination.
N-Chlorination of secondary amides. II. Effects of substituents on rates of N-chlorination
Authors: Thomm E. W. C. W. , Wayman M.
Published: May 2006

not available
Vapor–liquid equilibria in the system acetone–benzene
Authors: Campbell A. N. , Chatterjee R. M.
Published: May 2006

The saturation pressures and vapor–liquid compositions of 7 mixtures of the system acetone–benzene have been determined from a temperature of 100 °C and a pressure of about 2 atm up to the highest temperatures and pressures at which liquid and vapor coexist. The critical temperatures were determined by the disappearance-of-meniscus method.The P–T–X relations at the liquid–vapor phase boundaries, as obtained by the determination of the bubble-point pressure vs. temperature curves of a series of mixtures of known composition, do not indicate the existence of an azeotrope in the range of temperature and pressure of this research. The binary data have been treated thermodynamically to yield the liquid-phase activity coefficients. The partial molal volumes in the liquid mixture required for the Poynting correction (effect of pressure on liquid phase properties) for liquid-phase activity coefficients have also been obtained. The fugacity coefficient of a component in the vapor mixture has been obtained by a modified Redlich–Kwong equation, as suggested by Chueh and Prausnitz. Following their modification of the van Laar equation, several binary liquid phase parameters, such as the binary interaction constant, Henry's constant and dilation constant, as required for the solution model for excess Gibbs energy, have been calculated.
Orientation of azide addition to homoconjugated dienes
Authors: McDaniel R. S. , Oehlschlager A. C.
Published: May 2006

The 1,3-dipolarcycloaddition of phenyl azide to bicyclic dienes 8–10 proceeds readily at the angle strained double bond to give both 1,2,3-Δ2-triazoline isomers which would result from the two possible orientations of addition. The major triazoline isomer in each case is that resulting from stabilization of the dipolar transition state by the neighboring unreactive double bond. The structures of the triazolines were deduced from their nuclear magnetic resonance spectra in CCl4, CDCl3, and C6H6.
Some reactions of hydrazine with ruthenium compounds
Authors: Bottomley F.
Published: May 2006

Some reactions of hydrazine with pentachloroaquoruthenite(III) and ammine complexes of ruthenium(II) and ruthenium(III) have been investigated in acid, neutral, and alkaline solution. In neutral solution it has been shown that hydrazine monohydrochloride oxidized hexaammineruthenium(II) to hexaammineruthenium(III). In alkaline solution nitrogenpentaamrnineruthenium(II) was formed, and a mechanism for this reaction is postulated.
Use of zero-intensity extrapolations in photochemistry
Authors: Cala F. R. , Chong S-L. , Sperling H. P. , Toby S.
Published: May 2006

In many photochemical systems it is possible to determine the quantum yield of one of several primary processes by measuring the overall quantum yield of a suitable product and extrapolating to zero incident light intensity. This technique is examined for some generalized mechanisms and for some particular examples.
Réactions dans le sulfolane. V. Ions trihalogénures
Authors: Deneux M. , Benoit R. L.
Published: May 2006

Equilibria between I2 and I−, Br−, Cl− in sulfolane were studied by potentiometry and spectrophotometry at 30 °C. The stabilities of Br3− and Cl3− were also determined. The stability constants at nil ionic strength were calculated by means of a program: [Formula: see text], 7.23, and 7.23 for Y = I, Br, and Cl; [Formula: see text], 7.33, and 4.11 for X = I, Br, and Cl. The disproportionation equilibria [Formula: see text] were characterized by log Kd = −1.55(Y = Br) and −0.64 (Y = Cl). The stabilities and spectra of the trihalide ions in sulfolane are compared with similar data for other solvents.
Acid-catalyzed cyclization of mangostin
Authors: Yates Peter , Bhat H. B.
Published: May 2006

The acid-catalyzed cyclization of mangostin is shown to give products in which one, but not both, of the isopentenyl side chains gives rise to dihydropyran rings. The presence of a methoxyl group at C-7 and thus the structure originally assigned to mangostin is thereby confirmed.
Perfluoroalkyl vicinal dihypohalites
Authors: Janzen A. F. , Pollitt R.
Published: May 2006

The preparation of perfluoroalkyl vicinal dihypohalites is described. The new compounds were characterized by 19F nuclear magnetic resonance, infrared spectroscopy, and chemical reactions.
Cyclooctatetraenoquinones. I The synthesis and structure of dibenzo[a,e]cyclooctene-5,6-dione
Authors: Yates Peter , Lewars Errol G. , McCabe Peter H.
Published: May 2006

Dibenzo[a,e]cyclooctene-5,6-dione (18), a derivative of 1,2-cyclooctatetraenoquinone (4), has been synthesized by selenium dioxide oxidation of dibenzo[a,e]cycloocten-5(6H)-one (26), itself obtained from the reaction of 5,11-dibromo-5,6,11,12-tetrahydrodibenzo[a,e]cyclooctene (20) with dimethyl sulfoxide and collidine. Infrared and proton magnetic resonance spectroscopic studies have shown that the 8-membered ring of 18 is not aromatic.
Cyclooctatetraenoquinones. II. The synthesis and transformations of compounds related to dibenzo[a,e]cyclooctene-5,6,11(12H)-trione
Authors: Yates Peter , Lewars Errol G.
Published: May 2006

Bromination of 11-acetoxydibenzo[a,e]cycloocten-5(6H)-one (6) gave the 6-bromo derivative (8), which on further bromination gave a hydrogen bromide adduct (12 or 13) of 6,6,12-tribromodibenzo[a,e]cyclooctene-5,11(6H,12H)-dione (14). Treatment of this adduct with aqueous-ethanolic ammonia followed by sublimation gave 11-oxoindeno[1,2-c]isocoumarin (4), not dibenzo[a,e]cyclooctene-5,6,11(12H)-trione (3) as earlier suggested. The conversion of 12 or 13 to 4 has been shown to involve the formation of 3-bromo-2-(o-carboethoxyphenyl)indone (17), which gave 4 and ethyl bromide on being heated at 180°. Oxidation of dibenzo[a,e]cyclooctene-5,11(6H,12H)-dione with selenium dioxide gave a bimolecular product 25 considered to be derived by loss of carbon monoxide from the dimer of dibenzo[b,ƒ]pentalene-5,10-dione (27), a selenium-containing product, 28, and the hydrate 29 of 3.
Isolation of indole (β-carboline), pyridine, and indole–pyridine alkaloids from Naucleadiderrichii
Authors: McLean Stewart , Murray D. G.
Published: May 2006

The bark of N. diderrichii has afforded alkaloids of novel structure and of biogenetic significance. Pyridines, β-carbolines, and more complex alkaloids that contain both of these units or modifications of them have been identified among the bases isolated.
Total synthesis of spirobenzylisoquinoline alkaloids: (±)-ochotensimine
Authors: McLean Stewart , Lin Mei-Sie , Whelan John
Published: May 2006

A synthesis of ochotensimine that can be modified to lead to related spirobenzylisoquinoline alkaloids is described.
Lead tetraacetate oxidation of hindered alicyclic ketoximes
Authors: Just G. , Dahl K.
Published: May 2006

Lead tetraacetate oxidation of 2,2,6,6-tetramethylcyclohexanone oxime and structurally related ketoximes caused C—C bond fission to yield acetyl hydroxamates. Severely hindered ketoximes gave nitrile oxides as intermediates which were trapped by 1,3-dipolar cycloaddition reaction.
Platinum–acetylene or –ethylene complexes with bridging or chelating ethylenediamine derivatives
Authors: Theophanides T. , Kong P. C.
Published: May 2006

The reaction intermediates of K[Pt(ac)X3] with ethylenediamine and its N-substituted derivatives have been studied in water and organic solvents. The general reaction is [Formula: see text]where ac = (CH3)2C(Y)C≡CC(Y)(CH3)2, en = ethylenediamine, Y = OH, OCH3, and X = Cl, Br. The five-coordinate intermediates 2 are isolated and characterized from conductivity data, molecular weight determinations, and infrared, nuclear magnetic resonance (n.m.r.), and ultraviolet (u.v.)-visible absorption spectra. The stability of complexes 2 (see equation above) in terms of alkyl substitution of the NH2 groups is approximatelyenMe4 > enMe2Et2 > enH2Me2 > enwhere enMe4 = (CH3)2N(CH2)2N(CH3)2, enMe2Et2 = CH3C2H5N(CH2)2NC2H5CH3, enH2Me2 = CH3HN(CH2)2NHCH3, enEt4 = (C2H5)2N(CH2)2N(C2H5)2. In contrast to these reactions, the Zeise salt, K[PtC2H4Cl3], reacts with ethylenediamines and gives only stable, bridged compounds of the formula (PtC2H4Cl2)2(en). Bridged compounds, (Pt(ac)Cl2)2(en), are also obtained with K[Pt(ac)Cl3], but only in the presence of a large excess of KCl in the reaction solutions.
Circular dichroism of some copper(II) diamide complexes
Authors: Parris M. , Hodges A. E.
Published: May 2006

The absorption spectra and circular dichroism spectra of some Cu(II) N,N′-diglycylethylenediamine analogues are interpreted in terms of a square-planar structure of the biuret type.