bluuebunny/crossref_metadata_2025_split huggingface dataset:
The photoreactions of some N‐arylamides
Authors: Hageman H. J. 
Published: September 2010

AbstractAcetanilide and its N‐methylated derivative have been irradiated in solution. N‐Methylation appears to result in a higher conversion of the starting material and in the formation of a symmetrically tetrasubstituted hydrazine, in addition to the known ortho‐, and para‐rearranged products and aniline. Unexpectedly the o/p‐ratio of the products did not change upon N‐methylation.
Polyethyleneimine I: Fractionation; Mark‐Houwink relation
Authors: van den Berg J. W. A. , van Treslong C. J. Bloys , Polderman A. 
Published: September 2010

AbstractA relation between the limiting viscosity number [η] and the weight average molecular weight of polyethyleneimine (PEI) is proposed. Special care was taken to suppress the marked polyelectrolytic character of PEI in water for both viscometric and light‐scattering measurements. For these measurements various fractions were isolated in three different ways from some commercially available PEI′s, all having broad molecular weight distributions. To obtain an impression of the molecular weight distribution of the resulting fractions, some osmotic measurements to obtain the number average molecular weight and some ultra‐centrifuge runs were performed.
Absolute configuration of the cis‐9,10‐epoxystearic acid occurring in shorea robusta seed
Authors: Korver O. , Ward J. P. 
Published: September 2010

AbstractThe optical rotation of (+)‐cis‐9,10‐epoxystearic acid occurring in Shorea robusta seed fat, and its stereospecific, chemical conversion to (‐)‐erythro‐9,10‐dihydroxystearic acid proved that both of these acids have the absolute configuration 9S,10R. Circular dichroism (CD)‐measurements on complexes with praseodimium tris‐dipivaloylmethane are described.
C‐Nitroso compounds. Part XXVI: Photochemistry of C‐nitroso compounds. The photooxidation of ethylbenzene in the presence of 2‐methyl‐2‐nitrosopropane
Authors: Maassen J. A. , de Boer Th. J. 
Published: September 2010

AbstractRed light photolysis of 2‐methyl‐2‐nitrosopropane (t‐BuNO) in ethylbenzene in the presence of oxygen, leads to acetophenone and 1‐phenylethanol as main oxidation products via hydrogen abstraction by a photochemically generated adduct of oxygen to the nitroso compound. Yields and product distribution depend on the t‐BuNO concentration during the photooxidation, in accordance with the proposed mechanism.Other hydrocarbons with easily abstractable hydrogens react similarly.
The conversion of endoxides to aromatic compounds with triphenylphosphonium dibromide
Authors: de Wit J. , Wynberg Hans 
Published: September 2010

AbstractTriphenylphosphonium dibromide converts endoxides into aromatic compounds in good yields. Endoxides having a configuration in which the oxygen atom is shielded from attack by agents normally used for this conversion react under mild conditions. A possible mechanism, involving induced SN1 cleavage of the carbon‐oxygen bond in the endoxides is given.
Reactivity of 2,3‐,2,4‐ and 3,4‐dibromoquinoline towards potassium amide in liquid ammonia
Authors: den Hertog H. J. , Buurman D. J. 
Published: September 2010

AbstractAminations of 2,3‐, 2,4‐ and 3,4‐dibromoquinoline with potassium amide in different media have been investigated. Reactions of various types (bromine migration, dimerization, cine‐substitutions and various ring transformations) were found to occur.Mechanisms for the conversions observed are proposed.
Scytalidic acid, a novel compound from scytalidium species
Authors: Overeem J. C. , Mackor A. 
Published: September 2010

AbstractThe structure of scytalidic acid, a metabolite of Scytalidium FY strain and of Scytalidium album is shown to be 8‐butyl‐8‐hydroxy‐3‐pentyl‐1,5‐cyclononadiene‐1,2,5,6‐tetracarboxylic 1,2: 5,6‐dianhydride.Scytalidic acid is a new representative of the class of nine‐membered ring compounds comprising byssochlamic, glauconic and glaucanic acids and the rubratoxins.
Molybdenum‐catalysed epoxidation of olefins with alkyl hydroperoxides II. Isolation and structure of the catalyst
Authors: Sheldon R. A. 
Published: September 2010

AbstractThe catalysts isolated from the reaction mixtures of the molybdenum‐catalysed epoxidations of various olefins with tert‐butyl hydroperoxide were all found to be soluble Mo(VI)‐1,2‐diol complexes. The structure of the diol complex is directly related to the structure of the olefin being epoxidized and is independent of the type of molybdenum compound originally added as the catalyst. Separate experiments have shown that the diol complexes are formed in situ by reaction of the molybdenum catalyst with the epoxide in the presence of the hydroperoxide.
Activity coefficients of single ions (VI), in 1,4‐dioxane‐water and acetic acid‐water mixtures
Authors: Bax D. , de Ligny C. L. , Remijnse A. G. 
Published: September 2010

AbstractThe method for the estimation of standard chemical potential differences (Δμ°) of single ions, described previously, is applied to the transfer from water to 1,4‐dioxane‐water and acetic acid‐water mixtures.
Photodehydrocyclizations of stilbene‐like compounds VII: Synthesis and properties of the double helicene, diphenanthro[3,4‐c;3′,4′‐l]chrysene
Authors: Laarhoven W.H. , Cuppen Th. H. J. M. 
Published: September 2010

AbstractA description of two alternative routes (Schemes 1 and 2) for the synthesis of the title compound (I) is given. Only the second route resulted in the formation of the two diastereomers of I. The physical properties of both isomers are given. The reacemization is discussed.
Hydride transfer reactions. I: Intramolecular hydride shifts in alkyloxocarbonium ions
Authors: Brouwer D.M. , Roobeek C.F. , van Doorn J.A. , Kiffen A.A. 
Published: September 2010

AbstractThe occurrence of intramolecular 1,4‐hydride shifts from alkane carbon to oxocarbonium carbon in acyl cations has been demonstrated in the long‐lived 4‐methyl‐ and 3,4‐dimethylpentanoyl cations in FSO3HSbF5. Strong, though not conclusive evidence has been obtained for an intramolecular 1,5‐hydride shift in the hexanoyl cation. Attempts to observe a 1,5‐hydride shift in 5‐methyl‐hexanoyl ion were unsuccessful owing to the occurrence of side reactions; in FSO3HSbF5 this cation undergoes intermolecular hydride abstraction. The 1,4 shifts are much faster than 1,2‐ or 1,3‐hydride shifts to oxocarbonium carbon, as demonstrated by the absence of the latter reactions, under comparable conditions, in the pentanoyl, 3‐methylpentanoyl and 2‐methylbutanoyl ions. The differences in the relative rates of 1,2‐ 1,3‐ and 1,4‐hydride shifts between oxocarbonium and alkylcarbonium ions are discussed.
Solubilities of some tetra‐n‐butylammonium salts in liquid ammonia at −37°C. Specific conductances of the saturated solutions
Authors: Zwikker J.W. , Nieboer H. 
Published: September 2010

AbstractThe solubilities of (n‐C4H9)4NI, (n‐C4H9)4NClO4, (n‐C4H9)4NNO3 and (n‐C4H9)4NSCN in liquid ammonia at −37°C were determined gravimetrically. Specific conductances of the saturated solutions were measured. Tetra‐n‐butyl‐ammonium nitrate is recommended as supporting electrolyte for electrochemical experiments in liquid ammonia.
A simple preparative method for dithioesters
Authors: Meijer J. , Vermeer P. , Brandsma L. 
Published: September 2010

AbstractA number of dithioesters RC(S)SR′ (Ralkyl, aryl, 2‐thienyl; R′ = alkyl, allyl or propargyl) can be obtained in good yields by reaction of RMgX (X = Cl or Br) in tetrahydrofuran with carbon disulfide, followed by alkylation with alkyl iodides, allyl bromide or propargyl bromide.
Preparation, structure and properties of compounds containing the dipositive tri‐copper hexa(N,N‐di‐n‐butyldithiocarbamato) ion, compounds with copper in the oxidation states II and III
Authors: Cras J. A. , Willemse J. , Gal A. W. , Hummelink‐Peters B. G. M. C. 
Published: September 2010

AbstractThe preparation, some magnetic, spectral and electrochemical properties of the compounds [Cu3(Bu2dtc)6] [MBr3]2(M = Zn, Cd, Hg) are reported. The crystal structure of the compound [Cu3(Bu2dtc)6] [CdBr3]2 has been determined by a three‐dimensional X‐ray analysis. The triclinic cell, space group magnified image with a = 12.629(4), b = 13.706(4), c = 12.506(4) Å and α = 95.84(4). β = 91.45(4), γ = 86.06(3)°, contains one formula unit. Atomic parameters were refined to a conventional R value of 0.05 for 1344 independent non‐zero reflections. The structure consists of two centrosymmetric ionic units [Cu3(Bu2dtc)6]2+ and [Cd2Br6]2−. In the cation one copper atom has an apically distorted octahedral S‐coordination, with CuS distances of 2.30(1), 2.35(1) and 3.19(1) Å. The two other equivalent copper atoms have five‐fold pyramidal S‐coordinations with CuS distances of 2.21(1), 2.22(1), 2.23(1), 2.23(1) and 2.88(1) Å. The Cd2Br ion can be described as a slightly‐distorted edge‐condensed bitetrahedron. Esr single‐crystal spectra prove localisation of the unpaired electron at one copper atom. The I.R. spectra show double CuS and CN stretching frequencies. All these data suggest the compounds to be composed of copper in different states of oxidation. The cation can be described as [(Cu(III)(Bu2dtc)2)2Cu(II)(Bu2dtc)2]2+. The ionic structure is confirmed by conductivity measurements.
Photodehydrocyclizations of stilbene‐like compounds VIII: Synthesis of hexaheliceno[3,4‐c]hexahelicene
Authors: Laarhoven W. H. , de Jong M. H. 
Published: September 2010

AbstractThe synthesis of a new double helicene, hexaheliceno[3,4‐c]hexahelicene, has been described. Of two possible diastereomers only one has been obtained. Presumably the product has the racemic configuration but this assignment is not yet definite.
Infrared study of hydroxyl groups on nickel oxide and silica‐supported nickel catalysts
Authors: Erkelens J. , Eggink‐Du Burck S. H. 
Published: September 2010

AbstractThe decomposition of nickel hydroxide and the decomposition and reduction of some silica supported catalysts have been studied by means of IR spectroscopy.In the spectrum of decomposed nickel hydroxide two bands remain at 3676 and 3575 cm−1 which may be assigned to the existence of free and disturbed hydroxyl groups on the nickel oxide surface. The presence of these groups only partially explains the previously published water retention after decomposition. The band at 3676 cm−1 also remains in the spectrum of a silica‐supported nickel impregnation catalyst after heat treatment and disappears readily after reduction with hydrogen. IR absorption bands at other positions in other types of supported nickel catalysts possibly originate from the formation of nickel hydrosilicates.The decomposition of nickel hydroxide was also studied by means of thermogravimetry and it was found that the rate of decomposition at 225°C could be described by a first order law, provided that the degree of conversion was defined as being one at the apparent decomposition stage of about 80%.
Hydride transfer reactions III: Rates of hydride transfer from isobutane to hydroxycarbonium ions
Authors: Brouwer D. M. , Kiffen A. A. 
Published: September 2010

AbstractThe hydride transfer from isobutane to protonated acetaldehyde, to give t‐butyl ion and ethanol (which is subsequently protonated), proceeds at approximately the same rates (k = 6 − 9 × 10−4 M−1S−1 at 0°C) in 9:1 HF‐SbF5 and HF‐BF3. This indicates that protonation of the alcohol formed does not assist the hydride transfer step kinetically. The hydride transfer from isobutane to protonated acetone is slower than that to protonated acetaldehyde by a factor of about 3 × 103.
Chemistry of alkenethiolates. Six‐ and seven‐membered rings with two hetero atoms
Authors: Hoff S. , Blok A.P. , Zwanenburg E. 
Published: September 2010

AbstractThe S‐hydroxy, ‐amino and ‐mercapto alkylation of 2‐acetamidopropenethiolates II is described. Intramolecular cyclization of these functionalized alkenes to acetamido‐substituted 1,4‐oxathianes, 1,4‐dithiane, thiomorpholine, 1,4‐oxathiepane and 1,4‐dithiepane can be achieved in good yields in the presence of base or acid catalysts. The cyclization to 1,4‐oxathianes has been studied in detail and the configuration of the stereoisomers has been assigned on the basis of PMR spectroscopy.
Hydride transfer reactions: IV. Intramolecular hydride shifts in protonated aldehydes
Authors: Brouwer D.M. , Kiffen A.A. 
Published: September 2010

AbstractProtonated 4‐methylpentanal (1) in 9:1 HF‐SbF5 reacts to give equimolar quantities of 5,5‐dimethyltetrahydrofuryl ion and t‐C6H ions. As the reaction follows first‐order kinetics (k = 4 × 10−4 s−1 at 30°C) and under the same conditions no reaction takes place between protonated acetaldehyde and 5‐methylhexan‐2‐one it is concluded that the reaction of 1 involves an intra‐molecular 1,4‐hydride shift followed by intermolecular hydride transfer from another ion 1 to the resulting C‐protonated alkenol.The 1,4‐shift in 1 is at least fifteen times faster than the 1,3‐shift in protonated 3‐methylbutanal. The latter ion undergoes a first‐order reaction (with k = 8,3 × 10−5 s−1 at 40°C) but routes other than that involving a 1,3‐hydride shift cannot be ruled out.The rates of intermolecular and intramolecular hydride transfers to trialkyl‐, alkylhydroxy‐ and alkyloxocarbonium ions are compared, and the differences in relative rates of 1,2‐, 1,3‐ and 1,4‐shifts in these ions discussed.
Les sulfates acides de manganèse: I. L'hydrogénosulfate
Authors: Palavit Par G. , Noël S. 
Published: September 2010

AbstractThe manganese hydrogenosulfat is prepared according to the ternary diagram MnSO4‐H2SO4,‐H2O. It crystallizes in the spatial groups P21/c with two molecules in the cell. A frequences' attribution of the group HSO4 is proposed. From a thermal study, the hypothesis of a decomposition mechanism can be proposed.
Conformation of non‐aromatic ring compounds‐80: Calculation of dihedral angles from vicinal proton coupling constants in mono‐ and di‐substituted glutaric anhydrides
Authors: Koer F. J. , van Asbeck T. M. W. , Altona C. 
Published: September 2010

AbstractThe Lambert‐Buys R‐value method is applied to several six‐membered α‐mono‐α,α‐ and trans‐α,α′‐di‐substituted glutaric anhydrides. A discussion concerning the appearance of the AA′BB′ spectra of the compounds under consideration is given. The vicinal proton coupling constants Jtrans (7.3‐8.1 Hz) and Jcis (4.9‐6.4 Hz) and the corresponding ring dihedral angles (ψ: 49°‐53°) are reported. The results are interpreted in terms of small deformations of the “sofa” conformation due to steric effects of the substituents.
Charge transfer reactions of tris(dimethylamino)phosphine; Solvent effects and esr measurements
Authors: Boekestein G. , Buck H. M. 
Published: September 2010

AbstractIt is demonstrated that the course of the reaction of tris(dimethylamino)phosphine with aromatic bromides is strongly dependent on the nature of the solvent. The reaction in DMF or THF gave rise to the formation of radicals, which could be measured directly or by the method of spin‐trapping, using 2‐methyl‐2‐nitrosopropane as a scavenger.
Ligand hyperfine interactions in oxyhalides of pentavalent chromium, molybdenum and tungsten II
Authors: van Kemenade J. T. C. 
Published: September 2010

AbstractThe electron paramagnetic resonance (EPR) spectra of the ions CrOF5=, MoOF5=, WOF5=, MoOCl5=, MoOBr5=, WOCl5= and WOBr5=, all incorporated into a single crystal of a suitably chosen host lattice, are presented.An attempt is made to correlate the EPR parameters to bonding orbital coefficients by using the Abragam and Pryce method.The analysis of the ligand hyperfine tensor components in bonding coefficients gives satisfactory results for the oxyfluorides with an increase in orbital delocalisation going from chromium to molybdenum.The existing methods of correlating g‐ and A‐tensor to molecular orbital coefficients are reviewed critically and shown to be highly dependent on an arbitrary choice of a charge distribution over the complex.
Chemistry of cyclopropene II: Formation and reactions of 1‐potassio‐, 1‐sodio‐and 1‐lithiocyclopropene in liquid ammonia
Authors: Schipperijn A. J. , Smael P. 
Published: September 2010

Abstract1‐Metallocyclopropene is instantaneously and nearly quantitatively formed on addition of cyclopropene to an at least equimolar amount of alkali amide in liquid ammonia. Alkylation yields mono‐ and dialkylated cyclopropenes. On standing, 1‐metallocyclopropene slowly converts into a mixture of 1‐metallo‐,2‐cyclopropylcyclopropene, 1,2‐dicyclopropylcyclopropene and cyclopropylidenecyclopropane, in a yield that greatly depends on the reaction conditions. A detailed kinetic study has made it possible to select optimum reaction conditions for the formation of each of these products.A route has been developed for the synthesis of monoalkylated and 1,2‐dialkylated cyclopropenes, either with identical or with different alkyl groups.
The copper(II)‐ammonia complexes in the synthetic zeolites X and Y
Authors: Vansant E. F. 
Published: September 2010

AbstractThe EPR spectra of the cupric‐ammonia complexes in the zeolites X and Y were studied. Ammonia adsorption in the copper(II)‐X and ‐Y zeolites resulted in the formation of square planar Cu(II)‐NH3 complexes. Desorption of ammonia produced in both zeolites a distorted tetrahedral complex.
Preparation, properties and structure of dihalogenobis(N,N‐DI‐n‐butyldithiocarbamato) complexes of palladium and platinum
Authors: Willemse J. , Cras J. A. , Wijnhoven J. G. , Beurskens P. T. 
Published: September 2010

AbstractThe preparation and properties of M(Bu2dtc)2X2 (M = Pd, Pt and X = Br, I) are reported. From the platinum complexes two isomers were isolated. The crystal structure of the cis‐isomer of Pt(Bu2dtc)2I2 is determined by a threedimensional X‐ray analysis. The orthorhombic cell, space group Fddd, with a = 33.37(3), b = 34.16(3), c = 20.19(2) Å and V = 23010(40) Å3 contains 32 formula units. Atomic parameters were refined to a conventional R value of 0.073 for 1417 independent non‐zero reflections. The platinum atom is distorted octahedrally coordinated by two iodine and four sulfur atoms with average distances of Pt ‐ I = 2.66 and Pt ‐ S = 2.35 Å. The intra‐ and one of the intermolecular I‐I distances (resp. 3.79 and 3.37 Å) are short compared with an I‐I Van der Waals contact.ESCA spectra show the other isomer to be a Pt(IV) complex too. NMR data suggest a trans‐structure for this isomer.With Bu4tds these complexes yield M(Bu2dtc)3X (M = Pt, Pd and X = Br, I) of which some properties are given.
Some modifications of the aglycone lactone ring of erythromycin A
Authors: Bojarska‐Dahlig H. , Dziegielewska I. , Gła̧bski T. 
Published: September 2010

AbstractTreatment of 8,9‐anhydroerythromycin A 6,9‐hemiacetal with hydrogen peroxide leads to the N‐oxide of the 8,9‐epoxy derivative. The latter compound on catalytic reduction yields 8‐hydroxy‐9‐deoxoerythromycin A, forming the cyclic 6,8‐carbonate in reaction with ethylene carbonate.
Base‐catalyzed cyclisation of N,N‐dialkyl‐2,4‐pentadienethioamides to 2‐(dialkylamino)thiophenes
Authors: Meijer J. , Brandsma L. 
Published: September 2010

AbstractTreatment of N,N‐dialkyl‐2,4‐pentadienethioamides (1) with potassium tert‐butoxide in hexamethylphosphoric triamide causes cyclisation to substituted thiophenes (3) and (4).
Electron paramagnetic resonance of mixed oxalatochromium(III) complexes in frozen solutions
Authors: Andriessen W. T. M. 
Published: September 2010

AbstractElectron Paramagnetic Resonance (epr) spectra are reported for the following complexes in frozen solutions: K3Cr(ox)3 (g = 1.98 ± 0.01; D = 0.66 ± 0.09 cm−1; E < 0.05 cm−1), K[Cr(ox)2en]. KI (g = 1.98 ± 0.01; D = 0.61 ± 0.06 cm−1; E = 0.10 ± 0.01 cm−1), [Cr(en)2ox]I (g = 1.98 ± 0.01; D = 0.43 ± 0.09 cm−1; E = 0.09 ± 0.02 cm−1). For the powder spectrum of Cr doped waterfree K3Al(ox)3 the following parameters are reported: g = 1.982 ± 0.001; D = 0.666 ± 0.006 cm−1; E = 0.015 ± 0.001 cm−1.
Synthesis of 2‐(1‐alkenyl)furans and 2‐(1,3‐alkadienyl)furans
Authors: de Jong A.J. , Brandsma L. , Arens J.F. 
Published: September 2010

AbstractTreatment of the compounds HOCH2CHC(CH3)CCCH(R)OCH3 (R = H or CH3) and HOCH2CHC(CH3)CCC(R1)C(R2)CH2OCH3 (R1 and R2 = H or CH3) with potassium tert‐butoxide in dimethyl sulfoxide affords 2‐(1‐alkenyl)furans and 2‐(1,3‐alkadienyl)furans, respectively, in good yields.
A conformational study of aromatic N‐sulfinylamines
Authors: van Woerden H. F. , Bijl‐Vlieger S. H. 
Published: September 2010

AbstractElectric dipole moments and PMR spectra of a series of substituted N‐sulfinylanilines, Ar‐N=S=O, indicate that these compounds adopt preferentially a cis or syn structure (Z‐configuration) with respect to the central ‐N=S‐ bond. Direction and magnitude of the group moment of the NSO group are evaluated. From an analysis of the partial moments of the constituent atoms and groups, it appears that the lone pair of electrons in the non‐bonding sp2 orbital of sulfur contributes 1.8‐2.1 D to the total electric moment. In the light of the results obtained it seems likely that an analogous isomeric or rotameric form prevails in the corresponding aliphatic NSO compounds.
Preparation of 1,3‐dienyl ethers and thioethers by alkali amide induced elimination of alcohol, phenol or thiol from 1,4‐bis‐ethers and ‐thioethers derived from 2‐butene‐1,4‐diol
Authors: Everhardus R. H. , Peterse A. , Vermeer P. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractEthers and thioethers of the type RXCH2CH=CHCH2XR (X=O or S; R=alkyl or phenyl) undergo a 1,4‐elimination of RXH upon treatment with alkali amides in liquid ammonia, giving 1,3‐dienyl ethers and thioethers RX‐CH=CH‐CH=CH2 in good or excellent yields.
1,3‐Oxathioles as intermediates in nucleophilic additions to 1‐(acylthio)‐1‐alkynes III: Formation and reactivity of 1,3‐oxathiolium ions
Authors: Wevers H. , Drenth W. 
Published: September 2010

AbstractIn concentrated acids 1,3‐oxathiole (4) is rapidly converted into 1,3‐oxathiolium ion (5). In 0.10‐1.0 mol/1 aqueous perchloric acid ion 5 is quickly equilibrated with 2‐acyl‐1‐alkene‐1‐thiol (6) at a rate almost proportional to the reciprocal of the hydrogen ion concentration. At lower acidities the formation of compound 6 is preceded by the equilibration between ion 5 and an intermediate which is probably 2,5‐dialkyl‐2‐hydroxy‐1,3‐oxathiole (3). Rate constants of these reactions and the pKR⊕ value of ion 5a are obtained. Subsequently, the end product 1‐(acylthio)‐2‐alkanone (2) is formed from intermediate 3.
Dielectric properties of 1‐butanol and of mixtures of 1‐butanol with hexane and with tetrachloromethane
Authors: van den Berg J. F. , Michielsen J. C. F. , Ketelaar J. A. A. 
Published: September 2010

AbstractThe dielectric properties of 1‐butanol and of mixtures of 1‐butanol with hexane and with tetrachloromethane have been determined in the frequency range between 10KHz and 40GHz at temperatures from 249.0°K to 288.2°K.The Kirkwood correlation factor g computed from the dielectric constant is greater than 1 for 1‐butanol and for most mixtures. This is explained by an excess of the linear multimers with a high dipole moment formed by the association of molecules through hydrogen bonding. The greater part of the dispersion region is to be described by a relaxation process characterized with one relaxation time. The agreement between the dependence on concentration of the relaxation time and the correlation factor confirms the suggestion that this relaxation process is to be ascribed to the linear multimers. Linear multimers are present even in the dilute solution.