bluuebunny/crossref_metadata_2025_split huggingface dataset:
Investigations on organogermanium compounds. IV Transalkylation reactions between germanium compounds
Authors: Rijkens F. , Bulten E. J. , Drenth W. , van der Kerk G. J. M. 
Published: September 2010

AbstractTransalkylation reactions between germanium derivatives, including substituted digermanes, have been investigated. These reactions, which usually need a catalyst, e.g. a germanium dihalide, are tentatively explained by an electrophilic attack on the carbon atom of a germanium‐carbon bond of the alkyl‐donor. Many reactions reported in the literature which involve alkyl‐transfer among derivatives of the IVB group elements can be interpreted in the same way.
Preparation of some new derivatives ofmeta‐di‐tert‐butylbenzene
Authors: Knoester C. J. , de Koning A. J. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractSome new derivatives ofmeta‐di‐tert‐butylbenzene are described. The rates of deacetylation of a number of such derivatives are briefly discussed.
Preparation of some 4‐ or 5‐substituted 2‐tert.butylbenzoic acids
Authors: Baas J. M. A. , Wepster B. M. 
Published: September 2010

AbstractThe preparation of fifteen derivatives of 2‐tert.butylbenzoic acid, substituted in the aromatic nucleus in the 4‐ or the 5‐position, and of a 4,5‐disubstituted 2‐tert.butylbenzoic acid is described.
Synthesis and investigation of γ‐substituted α‐ethoxycarbonyl‐γ‐lactones
Authors: Maat L. , Sinnema A. , Beyerman H. C. 
Published: September 2010

AbstractTen γ‐substituted α‐ethoxycarbonyl‐γ‐butyrolactones (1–10) have been prepared from diethyl malonate and 1‐chloroalkan‐2‐ols. The scope and the course of the reaction are discussed. The products have been investigated by infrared and proton magnetic resonance methods. The lactones have been characterized by their anilides and some other derivatives.
Chemistry of propadiene. II. The addition of dichlorocarbene to propadiene
Authors: Peer H. G. , Schors A. 
Published: September 2010

AbstractThe addition of dichlorocarbene to propadiene has been investigated. The reaction between propadiene and dichlorocarbene obtained from chloroform and potassium t‐butoxide leads to tarry products. When generated by thermal decomposition of sodium trichloroacetate, the dichlorocarbene reacts with propadiene, yielding 1,1‐dichloro‐2‐methylenecyclopropane (II). The structure of this compound was established by means of infrared and NMR spectroscopy and confirmed by chemical means.
Electron diffraction by gases: The molecular structure of bicyclo[2,1,1]hexane
Authors: Dallinga G. , Toneman L. H. 
Published: September 2010

AbstractThe structure of bicyclo [2,1,1] hexane has been investigated by means of electron diffraction of the vapour. In the discussion of the results presented here, emphasis is on the ambiguities connected with the analysis of molecules containing many nearly equal interatomic distances.
Hetarynes XIV: Action of potassium amide on 2‐, 3‐ and 4‐bromoquinolines in liquid ammonia
Authors: den Hertog H. J. , Buurman D. J. 
Published: September 2010

AbstractBoth 3‐ and 4‐bromoquinoline when reacted with potassium amide in liquid ammonia, are converted into a mixture of 3‐ and 4‐aminoquinoline probably via 3,4‐quinolyne as an intermediate.2‐Bromoquinoline yields together with 2‐aminoquinoline, 2‐methylquinazoline as the result of a ring transformation.The mechanisms of the reactions are discussed.
Chemistry of α‐diazosulfones. Part IX. Synthesis of sulfonylcyclopropanes by addition of a sulfonylcarbene to alkenes
Authors: van Leusen A. M. , Mulder R. J. , Strating J. 
Published: September 2010

AbstractSulfonyl substituted cyclopropanes are formed in good yields on photolysis of p‐methoxyphenylsulfonyldiazomethane in the presence of alkenes. The reaction with cis‐ and trans‐2‐butene is stereospecifically cis, which may indicate that the intermediate sulfonylcarbene reacts in its singlet spin state.
The copper‐catalysed oxidation of unsaturated carbonyl compounds: Part VI: Synthesis of α,β‐unsaturated γ‐lactams by oxidative coupling of unsaturated ketones and ammonia
Authors: Volger H. C. , Brackman W. 
Published: September 2010

AbstractOxidative coupling by oxygen of ammonia and α,β‐or β,γ‐unsaturated ketones containing a primary γ‐carbon atom in a homogeneous solution of a copper ammonia methoxide catalyst in methanol leads to the formation of α,β‐unsaturated γ‐lactams in moderate yield.
Enthalpies of solvation of alkali metal and halide ions in N‐methylformamide and N‐methylacetamide at 25°
Authors: Weeda L. , Somsen G. 
Published: September 2010

AbstractMeasurements of the enthalpies of solution of LiI, NaI, KF, KCl, KBr, KI, RbI and CsI in N‐methylacetamide at 35° with an adiabatic calorimeter are reported.A calculation of the ionic enthalpies of solvation of the alkali metal and halide ions in N‐methylformamide and N‐methylacetamide is given. From the difference in ionic enthalpy of solvation of the fluoride and the potassium ions in water, formamide, N‐methylformamide and N‐methylacetamide, respectively, the quadrupole moments of these solvent molecules have been calculated.
The conformation of non‐aromatic ring compounds. Part 35: Trimethylene Sulfite and Related Compounds
Authors: van Woerden H. F. , Havinga E. 
Published: September 2010

AbstractA series of 2‐substituted trimethylene sulfites have been synthesized; in most cases two stereoisomers were isolated. The geometric and conformational characteristics were studied by the determination of dipole moments in carbon tetrachloride and in benzene, as well as by taking infrared spectra in various solvents and in the solid state (KBr discs). It is concluded that the SO bond has a preference for the axial position, its A‐value amounts to −3.5 ± 1 kcal/mole. The stretching frequency of the SO bond is 1190‐1205 cm−1 in the axial position and 1230‐1250 cm−1 in the equatorial position. The dipole moments can be quantitatively interpreted in a consistent way by assuming the partial moment of the sulfite group to be 2.5 D (CH  0 D), and its direction significantly deviating from the SO bond direction (Fig. 2).
Efficiency of chromatographic procedures. Part IV: The efficiency of paper chromatography on various kinds of Whatman paper and of thin‐layer chromatography on various kinds of cellulose powder for the separation of amino‐acids
Authors: de Ligny C. L. , Remijnse A. G. 
Published: September 2010

AbstractAn improved equation for the efficiency of strip chromatography (i.e., paper and thin‐layer chromatography) is derived.This equation is used to investigate the efficiency of ten kinds of Whatman chromatography paper and of six kinds of cellulose powder for the separation of amino‐acids by means of a 4: 1: 5 butanol ‐ acetic acid ‐ water mixture.
The synthesis of lactones. Part I: Saturated δ‐ and ϵ‐Lactones
Authors: Lardelli G. , Lamberti V. , Weller W. T. , de Jonge A. P. 
Published: September 2010

AbstractA homologous series of δ‐ and ϵ‐lactones has been synthesized, as well as some branched‐chain δ‐lactones.The δ‐lactones have been prepared by oxidation of 2‐alkylcyclopentanones or 2,5‐dialkylcyclopentanones with Caro's acid or by hydrogenation of corresponding oxo acids. The latter were obtained by chromic acid oxidation of these 2‐alkylcyclopentanones, or by Cason synthesis from 4‐methoxycarbonyl‐butanoyl chloride and dialkylcadmium, or by condensation of vinyl ketones with diethyl malonate.The alkylcyclopentanones were prepared by catalytic hydrogenation of 2‐alkylidenecyclopentanones obtained by aldol condensation of cyclopentanone and alkanals. The 2,5‐dialkylcyclopentanones, used as starting compounds for branched‐chain δ‐lactones, were obtained either by aldol condensation or by Dieckmann synthesis.A general method for the preparation of ϵ‐lactones (lactonisation of 6‐hydroxy acids under the influence of aromatic sulfonic acid) has been developed.Some physical constants of the pure compounds (including the intermediates) and of some of their characteristic derivatives have been determined.
Salcomine‐catalyzed oxidations of some phenols: A new method for the preparation of a number ofpara‐benzoquinones
Authors: van Dort H. M. , Geursen H. J. 
Published: September 2010

AbstractBis(salicylidene)ethylenediiminocobalt(II) (salcomine)* is a homogeneous catalyst for the oxidation of phenols with molecular oxygen in solutions of chloroform or methanol at room temperature. A number of substituted phenols with a freepara‐position have been studied; in most cases the correspondingpara‐benzoquinone was the main reaction product. Compounds originating from coupling of aryloxy radicals were also detected or isolated. Some speculations on the mechanism of the reaction have been made.
The preparation of Ca, Sr, Cd and Mn antimonites
Authors: Wanmaker W. L. , Hoekstra A. H. , Verriet J. G. 
Published: September 2010

AbstractBy heating CaO, SrO, CdO or MnCO3, in a non‐oxidizing atmosphere, with Sb2O3 it was possible to prepare some new antimonites, viz.: CaSb2O4, Ca2Sb2O5, Ca3Sb2O6, SrSb2O4, Sr2Sb2O5, CdSb2O4, Cd3Sb2O6 and Mn3Sb2O6. The X‐ray powder diagrams of the compounds synthesized and the reflection spectra of some of the antimonites are given. The thermal stability was determined by heating in an atmosphere of nitrogen on a thermobalance.
Cyclic sulfites of glycerol and its chlorohydrins
Authors: van Woerden H. F. , van Valkenburg Clara F. , van Woerkom G. M. 
Published: September 2010

AbstractThe synthesis is described of some cyclic sulfites derived from glycerol, glycerol α‐ and β‐monochlorohydrin and 2,2‐dichloropropane‐1,3‐diol.
Chemistry and spectroscopy in strongly acidic solutions. Part III: Formation of two different entities on protonation of formic acid
Authors: Hogeveen H. , Bickel A. F. , Hilbers C. W. , Mackor E. L. , Maclean C. 
Published: September 2010

AbstractIt has been shown by NMR spectroscopy that protonation of formic acid in HF‐BF3 solution leads to an equilibrium mixture of two different proton adducts, which probably differ in the configuration around the partly double carbon‐oxygen bond. Diffusion‐controlled proton transfer reactions take place between the stable protonated species (which are not directly interconvertible under the experimental conditions) and fluoride anions. No evidence has been found of the occurrence of protonated CO.
Decomposition of dimeric α‐nitrosocarboxylic acids in sulfuric acid
Authors: Duynstee E. F. J. , Mevis M. E. A. H. 
Published: September 2010

AbstractWhen dimeric α‐nitrosocyclohexanecarboxylic acid (I) is dissolved in cold concentrated sulfuric acid, rapid decomposition occurs and two products can be isolated. The first is a product to which we tentatively assign structure II (cyclohexanespiro‐4′‐(4′,5′‐dihydro‐1′,2′,3′‐oxadiazol‐5′‐one‐3′‐oxide)). The second product is cyclohexene‐1‐carboxylic acid. Dimeric α‐nitrosoisobutyric acid does not give an analogous decomposition.
Mass spectra of the tetramethyl and tetraethyl compounds of carbon, silicon, germanium, tin and lead
Authors: de Ridder J. J. , Dijkstra G. 
Published: September 2010

AbstractThis paper reports the monoisotopic mass spectra of the tetramethyl and tetraethyl compounds of carbon, silicon, germanium, tin and lead.Metastable ion transitions and appearance potentials are given. The primary ionization results in an electron deficiency on the metal atoms, which attain electron configurations similar to those of the third‐group elements. The stabilities of the valence states of these elements explain the cracking patterns.
Absolute configuration of (‐)‐β‐hydroxy‐β‐(m‐hydroxyphenyl)‐propionic acid
Authors: Deljac A. , Balenović K. , Urbas B. 
Published: September 2010

Abstract(‐)‐β‐Hydroxy‐β‐(m‐hydroxyphenyl)propionic acid has been correlated with D‐mandelic acid through reaction stages (I‐VII). The resulting absolute configuration is represented by the projection formula VI. As consequence of this correlation (‐)‐m‐hydroxymandelic acid (VII) must also belong to the D‐series of α‐hydroxy‐acids.
pH‐measurements in alcohol‐water mixtures. On the use of aqueous standard buffer solutions for calibration
Authors: Gelsema W. J. , de Ligny C. L. , Blijleven H. A. 
Published: September 2010

AbstractTo investigate the variation with alcohol‐percentage of the standard potential of glass electrodes of a wide range of types and manufactures, e.m.f.‐measurements have been made on cells of the type: glass electrode/standard buffer solution/saturated KCl‐solution (aq.)/Hg2Cl2‐Hg, using standard succinate buffer solutions in methanol‐water and ethanol‐water mixtures.An analysis is given of the accuracy of pH‐determinations in alcohol‐water mixtures, using both standard buffer solutions in the same solvent and aqueous standard buffer solutions for calibration.
Aromatic sulfonation. Part XVII: Kinetics and mechanism of the sulfonation of chlorobenzene in aqueous sulfuric acid
Authors: Kort C. W. F. , Cerfontain H. 
Published: September 2010

AbstractChlorobenzene has been sulfonated homogeneously in aqueous sulfuric acid varying from 83.4 to 99.6 wt‐%, at 25°. The isomer distribution‐98.8% para, 0.8% ortho, 0.4% meta ‐ is constant over the acid range studied. The substrate isotope effect has been determined under conditions of rapid hydrogen exchange; kD/kH varies from 0.8 in 95% sulfuric acid to 0.4 in 97%. The dependence of the reaction rate and the isotope effect on the acid concentration is explained by an SE2‐mechanism involving attack by H2S2O7 followed by proton removal from the σ‐complex by HSO4−; the latter process is partly rate‐limiting at high acid concentrations.
Proton magnetic resonance spectra of protonated dialkyl ketones: (Dialkylhydroxycarbonium ions)
Authors: Brouwer D. M. 
Published: September 2010

AbstractProton magnetic resonance spectra of eight protonated dialkylketones (dialkylhydroxycarbonium ions) have been measured in HF ‐ SbF5. Due to restricted rotation about the partially double C ‐ O bond, which leads to synanti isomerism, symmetric ketones (R1 = R2) give cations with non‐equivalent alkyl groups. Unsymmetric ketones (R1 ≠ R2) give two isomeric cations which are spectroscopically distinguishable below 0°C. The free energy barrier to rotation is at least 17 kcal/mole. Assignments of the observed PMR signals to the one or the other isomer of dialkylhydroxycarbonium ions are given. The preference of the hydroxyl proton for being syn to an alkyl group increases in the order tert‐butyl < neopentyl, ethyl, isopropyl < methyl. For methyl tert‐butyl ketone, the isomer ratio is about 15. The preferred conformations about the OC ‐ Cα bond of the alkyl groups are discussed on the basis of observed chemical shifts and stabilities.
Cyclopentadienyl(triphenylphosphine)nickel(II) halides
Authors: van den Akker M. , Jellinek F. 
Published: September 2010

AbstractThe cyclopentadienyl(triphenylphosphine)nickel(II) halides C5H5NiPPh3X with X = Cl, Br, I, have been synthesized in good yields from nickelocene and triphenylphosphonium halides. Some chemical, physical and crystallographic properties of the complexes are given and their electronic, infrared and particularly their proton‐magnetic‐resonance spectra are discussed. The iodide forms an inclusion compound with hexane of composition C5H5NiPPh3I · 1/2C6H14.
Conformation of non‐aromatic ring compounds. Part 41. Dipole moments and NMR spectra of 1,1,2‐trihalogeno‐cyclo‐hexanes and ‐cyclopentanes
Authors: Buys H. R. , Altona C. , Havinga E. 
Published: September 2010

AbstractThe dipole moments and NMR spectra of 1,1,2‐trihalogeno‐cyclohexanes and ‐cyclopentanes in several solvents are reported. The low‐field part of the NMR spectra, due to the proton in the CHX‐moiety, yields J = JAX + JBX. Equilibrium studies are carried out with the aid of the J‐values of the equilibrating and the conformationally homogeneous compounds. The equatorial conformer is found to be the predominant one. Long‐range coupling constants (4J) are determined for a number of these compounds.
Covalency effects in the spectrum of the tetrachloroferrate(III) anion
Authors: Balt S. 
Published: September 2010

AbstractThe ligand field approach to the interpretation of the visible spectrum of the tetrachloroferrate(III) anion has been critically reviewed. The influence of differences in the delocalisation of the metal t2 and e orbitals has been considered. This covalency influence could be worked out either by using different nephelauxetic parameters or by introducing different crystal field parameters. Both approaches were found to give a satisfactory explanation of the relative positions and the number of bands in the spectrum, although the agreement between calculated and observed energies is not very good.
Complexes with ligands containing nitrile groups Part I. Methyl cyanide complexes of mono‐ and di‐valent metal chlorides with antimony pentachloride
Authors: Zuur A. P. , Groeneveld W. L. 
Published: September 2010

AbstractThis paper describes systems of mono‐ and di‐valent metal chlorides with antimony pentachloride in methyl cyanide. The Cl−‐ion transfer, which occurs between the chlorides and antimony pentachloride in solution, has been studied conductometrically. This transfer is discussed on the basis of electrostatic theory.In the solid state, complexes of the types M+1(CH3CN)xSbCl6− and M2+(CH3CN)y(SbCl6−)2 are isolated. The mono‐ and di‐valent metal ions are solvated by the methyl cyanide molecules. Magnetochemical measurements indicate that the divalent transition metal ions are surrounded octahedrally by six methyl cyanide molecules.
The chemistry, herbicidal and fungicidal activities of 2,1,3‐benzothiadiazoles
Authors: van Daalen J. J. , Daams J. , Koopman H. , Tempel A. 
Published: September 2010

AbstractThe synthesis and test results on the herbicidal and fungicidal activities of a large number of 2,1,3‐benzothiadiazoles, mainly 4,5,7‐trisubstituted derivatives, are described and discussed.
Kinetics of the desulfonation of benzenesulfonic acid and the toluenesulfonic acids in aqueous sulfuric acid
Authors: Wanders A. C. M. , Cerfontain H. 
Published: September 2010

AbstractThe kinetics of the desulfonation of benzenesulfonic and the isomeric toluenesulfonic acids have been studied at 120‐155° in 65‐85 wt‐% sulfuric acid with the aid of an inert gas (nitrogen) stripping technique. All reactions were found to be of the first order with respect to the initial sulfonic acid. At high temperatures and/or high sulfuric acid concentrations substantial isomerisation of the toluenesulfonic acids took place, especially at low nitrogen flow rates.The rate‐constants of the desulfonation step proper ‐ i.e. the rate‐constants corrected for resulfonation ‐ increase with increasing acid concentration and temperature. The dependence of the rate of desulfonation on acidity is compatible with the sulfonation mechanism recently proposed by Kort and Cerfontain40, if the sulfonate anion is supposed to be the active substrate species in the desulfonation reaction.Partial rate‐factors for protodesulfonation of the toluenesulfonic acids and the tert‐butylbenzenesulfonic acids have been calculated. For a given alkyl substituent fo > fp >> fm. The protodesulfonation obeys the Selectivity Relationship. It is, therefore, suggested that the protodesulfonation of arenesulfonic acids in aqueous sulfuric acid proceeds via a Wheland‐type intermediate.
Mass spectra of some tetra‐alkylgermanium compounds
Authors: de Ridder J. J. , van Koten G. , Dijkstra G. 
Published: September 2010

AbstractThis paper reports the monoisotopic mass spectra of the compounds Ge(Alkyl)4, in which Alkyl = methyl, ethyl, propyl, butyl, pentyl and hexyl. With the aid of metastable ion transitions the fragmentation patterns could be given. With the exception of GeMe4 these are all similar and can be explained by a few rules, the first being the tervalence of the Ge after primary ionization. In GeMe4 splitting off of alkene fragments is difficult. As the alkyl chain length increases hydrocarbon ion abundance increases considerably.
Studies on cyclohexane derivatives. Part VI: cis‐ and trans‐1,4‐Di‐t‐butylcyclohexane. Preparation and properties
Authors: van Bekkum H. , Hoefnagel M. A. , de Lavieter L. , van Veen A. , Verkade P. E. , Wemmers A. , Wepster B. M. , Palm J. H. , Schäfer L. , Dekker H. , Mosselman C. , Somsen G. 
Published: September 2010

Abstractcis‐ and trans‐1,4‐Di‐t‐butylcyclohexane have been prepared. Evidence is presented showing that the cis‐isomer is mainly in a non‐chair conformation.The enthalpy difference between the two isomers in the liquid state at 25° is 4.7 kcal/mole, the trans‐isomer having the lower strain.
NMR substituent constants in benzene derivatives: Short communication
Authors: van Meurs N. 
Published: September 2010

AbstractThe ortho, meta and para substituent constants of 18 benzene substituents have been determined for dilute solutions in carbon tetrachloride. They enable the ring‐proton chemical shifts of di‐ and tri‐substituted benzenes with isolated groups to be calculated within 0.05 ppm from the experimental values. In the case of 2 adjacent substituents the meta and para substituent constants generally remain unchanged, whereas the ortho constants are often dependent upon the neighbouring substituents.
Polynuclear heterocyclic systems. Part V: Heterocycles related to steroids and C‐nor‐steroids
Authors: van Hes R. , Skolnik S. , Pandit U. K. , Huisman H. O. 
Published: September 2010

AbstractThe preparation of 6‐methoxy‐2‐(2′‐oxocyclopentyl‐1‐tetralone (I) and 2‐(2′‐oxocyclopentyl)quinolizidin‐1‐one (II) is described. Diketones I and II have been converted to heterocyclic systems related to steroids and C‐nor‐steroids.
Synthesis of 2‐deoxyinosadiamines‐1,3 including 2‐deoxystreptamine
Authors: Dijkstra D. 
Published: September 2010

AbstractHydrogenation of 4,6‐dinitropyrogallol over a rhodium‐platinum catalyst yielded 2‐deoxy‐cis‐inosadiamine‐1, 3 as the main product. This was converted into 2‐deoxy‐epi‐inosadiamine‐1, 3 by catalytic oxidation followed by trans‐directing reduction. From the epi‐isomer, 2‐deoxystreptamine was prepared by a similar oxidation/reduction procedure.
The 5,6‐dihydrothiazolo[2,3‐b]thiazolium system
Authors: Bradsher C. K. , Jones W. J. 
Published: September 2010

AbstractThe cyclization of hydrohalide salts of 2‐(2‐thiazolinthio) methyl ketones to yield the first simple 5,6‐dihydrothiazolo[2,3‐b]thiazolium salts has been carried out. It is believed that the transformation which 3‐methyl‐5,6‐dihydrothiazolo‐[2,3‐b]thiazolium perchlorate undergoes in alkaline solution and in the presence of air involves ring opening and oxidation of the resulting mercaptan to a disulfide.
Organophosphorus compounds VII: The absolute configuration of sarin and related anticholinesterases established by chemical correlation
Authors: Benschop H. P. , van den Berg G. R. , Boter H. L. 
Published: September 2010

AbstractThe reaction of (+)‐(i‐PrO)MeP(O)SMe with phenylmagnesium bromide in tetrahydrofuran affords (+)‐(i‐PrO)MeP(O)Ph, representing the first example of a stereospecific synthesis of a phosphinate ester from a phosphonothiolate ester. Levorotatory (MeS)MeP(O)Ph is converted into (R)‐(+)‐n‐PrMeP(O)Ph with inversion of configuration by reaction with n‐propylmagnesium bromide. The two Grignard reactions are correlated by the conversion of (‐)‐(MeS)MeP(O)Ph into (+)‐(i‐PrO)MeP(O)Ph with potassium isopropoxide.The correlation of the configuration of (R)‐(+)‐n‐PrMeP(O)Ph with that of (+)‐(i‐PrO)MeP(O)SMe by means of the fore‐mentioned reactions determines the absolute configuration of (+)‐(i‐PrO)MeP(O)SH to be (s). Since the latter compound is a common precursor for the synthesis of several types of optically active anticholinesterases, the absolute configurations of these could also be deduced, e.g. (R)‐(‐)‐isopropyl methylphosphonofluoridate (sarin).