bluuebunny/crossref_metadata_2025_split huggingface dataset:
The synthesis of pentacyclic systems by the Diels‐Alder reaction of dicycloalkenyls with cinnamic acid and related compounds
Authors: Maoz N. , Vromen S. 
Published: September 2010

AbstractThe Diels‐Alder reaction between dicycloalkenyls and aromatic α‐β unsaturated acids and esters was investigated. Suitable conditions for the cyclization of the adducts leading to fluorenone conditions were found. The nature of the isomerization, observed in some cases, is discussed.
A colorimetric assay method for microquantities of quaternary ammonium detergents
Authors: van Steveninck J. , Maas M. 
Published: September 2010

AbstractA sensitive and quick assay method was required for the determination of cationic detergents in aquous solution of biological origin. A number of assay methods for cationic detergents has been published (e.g.1,2,3,4). The best results were obtained with the colorimetric method, described by Auerbach2, the principle of which is the formation of a colored complex between bromophenol blue and the detergent. This colored complex can be extracted from aqueous solution, with an appropriate solvent, and measured colorimetrically.
On the liquid phase air oxidation of n‐heptane
Authors: Bigot J. A. , Kerkhoffs P. L. , Theeuwen H. 
Published: September 2010

AbstractThe amounts of isomeric heptanols and heptanones formed during liquidphase air oxidation of n‐heptane at 150‐160 °C were determined. It was found that the amounts of 2‐heptanone and 2‐heptanol were larger than could be expected statistically. This is explained by a slightly faster attack on the methylene groups near the chain ends during oxidation.
Doubling of the methyl doublet in some isopropyl compounds with an asymmetric centre
Authors: van der Vlies C. 
Published: September 2010

AbstractThe methyl resonance patterns of some isopropylcarbinols and isopropyl esters are described and discussed. The important influence of a phenyl nucleus on these patterns is obvious. The presence of such a nucleus as well as that of an asymmetric centre is a prerequisite for doubling of the methyl doublet in the case of the esters. It could not be established whether the doubling is due to intrinsic asymmetry, to preferential conformations, or to both factors.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia v. Experiments with trans‐1‐chloro‐2‐butene and 3‐chloro‐1‐butene
Authors: Verkade P. E. , de Vries K. S. , Wepster B. M. 
Published: September 2010

AbstractThe reaction of trans‐1‐chloro‐2‐butene with solutions of lithium, sodium, or potassium in liquid ammonia yields mainly trans‐2‐butene, 2,6‐octadiene, and 3‐methyl‐1,5‐heptadiene. Under the same conditions 3‐chloro‐1‐butene yields mainly trans‐ and cis‐2‐butene (in a ratio of about 2 : 1), 3‐methyl‐1,5‐heptadiene, and 3,4‐dimethyl‐1,5‐hexadiene. The composition of the “bibutenyls” provides strong evidence that these products are formed in an SN2 reaction between carbanion and chloride.
Synthesis of all‐cis methyl 3,6,9,12‐octadeca‐tetraenoate, methyl 4,7,10,13‐nonadecatetraenoate and methyl 5,8,11,14,17‐eicosapentaenoate
Authors: Pabon H. J. J. , van der Steen D. , van Dorp D. A. 
Published: September 2010

Abstract4,7,10,13‐Nonadecatetraynoic acid and 5,8,11,14,17‐eicosapentaynoic acid were synthesized via coupling of 1‐bromotetradecatriyne or ‐tetrayne with 4‐pentynoic or 5‐hexynoic acid respectively. 3,6,9,12‐Octadecatetraynoic acid could not be prepared in this way; it was obtained via the corresponding tetraynol. All poly‐ynoic acids were esterified and partially hydrogenated to the corresponding all cis‐enoic acids.Difficulties in the partial hydrogenation of 4,7,10,13,16,19‐docosahexaynoic acid, described in a previous paper, were overcome.
Decarbonylation of α‐hydroxylaminocarboxylic acids
Authors: Duynstee E. F. J. , Hennekens J. L. J. P. , Mevis M. E. A. H. 
Published: September 2010

AbstractAliphatic and cycloaliphatic α‐hydroxylaminocarboxylic acids are smoothly decarbonylated in dilute oleum at room temperature. For example, α‐hydroxyl‐aminocyclohexanecarboxylic acid (II) gives a high yield of carbon monoxide and caprolactam. Other α‐hydroxylaminocarboxylic acids give CO and oxime, or CO and a product that may be considered to have formed from the oxime by Beckmann rearrangement.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (iii) conversion of 2,6‐dibromopyridine by potassium amide in liquid ammonia into 4‐amino‐2‐methylpyrimidine
Authors: den Hertog H. J. , van der Plas H. C. , Pieterse M. J. , Streef J. W. 
Published: September 2010

AbstractReactions of 6‐substituted derivatives of 2‐halogenopyridines with potassium amide in liquid ammonia have been investigated.Together with aminations leading to the formation of 2‐amino compounds, two unusual reactions were found to occur, i.e. reactions partially involving meta‐rearrangement and conversions involving a ring transformation.The rearrangements took place in aminations of various substances (e.g. of 2‐bromo‐6‐methylpyridine, 2‐chloro‐6‐methylpyridine and 2‐bromo‐6‐ethoxypyridine). Ring transformations occurred in aminations of 2,6‐dibromo‐ and 2,6‐dichloro‐pyridine, 4‐amino‐2‐methylpyrimidine being formed.The mechanism of the remarkable reaction last‐mentioned is discussed.
Stability constants of nickel (II), cobalt (II) and copper (II) complexes of some optically active and racemic amino‐acids
Authors: Ritsma J. H. , Wiegers G. A. , Jellinek F. 
Published: September 2010

AbstractThe stability constants of nickel (II), cobalt (II) and copper (II) complexes of glutamic acid, aspartic acid, asparagine, and glutamine have been determined in aqueous solutions, containing either the pure L‐form or both the D‐ and L‐forms of the ligands. No significant differences were found between the stabilities of corresponding ML2 and MDL complexes in solution.
Heterocyclic diazo compounds. Part I. Preliminary communication
Authors: Engberts J. B. F. N. , van Bruggen G. , Strating J. , Wynberg Hans 
Published: September 2010

AbstractThe preparation of 2‐thienyl‐ and 2‐furyldiazomethane is described. Evidence for a carbene intermediate on photolysis of 2‐thienyldiazomethane is given.
The reaction of acetone with hydrogen sulfide
Authors: van Dort H. M. , Mijs W. J. 
Published: September 2010

AbstractA crystalline compound (“tetrathiopentone”, C15H28S4) has been isolated in high yield from the reaction of acetone with hydrogen sulfide in an acidic medium. Its structure was established as, 2,2,4,4,8,8,10,10‐octamethyl‐3,5,7,9‐tetrathiaspiro[5,5]undecane (I).
Studies in group IV organometallic chemistry. XXI. Mechanism of the hydrostannation of Isocyanates and Isothiocyanates
Authors: Leusink A. J. , Budding H. A. , Noltes J. G. 
Published: September 2010

AbstractThe mechanism of the addition of organotin mono‐hydrides across the CN bond of isocyanates and the C = S bond of isothiocyanates has been studied more closely. A polar mechanism is operative in both types of additions as appeared from the lack of activity of free radical generators and free radical scavengers and from the considerable influence of the polarity of the solvent on the rate of reaction. Kinetics, isotope effects and the influence of substituents attached to both the hydride and the unsaturated partner on the rate of addition, strongly point to a nucleophilic attack of the organotin hydride hydrogen on carbon as the first and rate‐determining step.
Synthesis and physiological properties of some heterocyclic‐aromatic sulfides and sulfones. VII: Determination of the stereochemical configurations by I.R.‐ and N.M.R.‐spectrometry
Authors: Trompen W. P. , Kruk C. , van der Haak P. J. , Huisman H. O. 
Published: September 2010

AbstractThe determination of the stereochemical configurations of a number of ringsubstituted aromatic and aromatic‐hetereocyclic ethene thioethers by I.R.‐ and N.M.R.‐spectrometry is reported.
Photoreactions of aromatic compounds VI: The mechanism of the photohydrolysis of m‐nitroanisole
Authors: de Jongh R. O. , Havinga E. 
Published: September 2010

AbstractThe photohydrolysis of m‐nitroanisole in alkaline media has been investigated by kinetic (quantum yield) measurements and by 18O‐tracer experiments. It is concluded that the reaction can be described as a bimolecular nucleophilic substitution reaction at the aromatic carbon bearing the methoxy group. Possibly, OH− is bound to the π→π* excited m‐nitroanisole to form a s‐complex that subsequently changes into either the starting material or the reaction products (m‐nitrophenol and methanol).
Electrophilic displacement of the formyl and acetyl group in 2,4,6‐trimethoxybenzaldehyde and 2,4,6‐trimethoxyacetophenone
Authors: Strating J. , Thijs L. , Zwanenburg B. 
Published: September 2010

AbstractBy reaction of 2,4,6‐trimethoxybenzaldehyde and 2,4,6‐trimethoxyacetophenone with sulfuryl chloride an electrophilic displacement of the formyl and acetyl groups takes place prior to chlorination in the 3 and 5 positions. 2,4,6‐Trimethoxybenzophenone gives the normal chlorination product.
Chemistry of α‐diazosulfones. VII: acid‐induced cyclization reactions of β′‐alkoxy‐α‐diazosulfones
Authors: van Leusen A. M. , Richters P. , Strating J. 
Published: September 2010

AbstractThe cyclization reaction of two new α‐diazosulfones [α‐methoxyphenyl‐sulfonyldiazomethane (I) and 2‐(benzyloxy)ethylsulfonyldiazomethane (II)], effected by hydroxyfluoroboric acid, afforded 1,3‐benzoxathiolane‐3,3‐dioxide (III) and 1,3‐oxathiolane‐3,3‐dioxide (IV) respectively. These hitherto unknown ring compounds have been prepared also by independent methods.
Complex formation and isomerization of propyl bromides with aluminium bromide investigated by microwave measurements
Authors: Adema E. H. , Teunissen A. J. J. M. , Tholen M. J. J. 
Published: September 2010

AbstractThe complex formation ofn‐propyl bromide and isopropyl bromide with aluminium bromide in carbon disulfide has been investigated by means of microwave measurements. The results are explained with the formation of 1: 1 complexes according to:with the equilibrium constants K9= 1.3 1/mole and K3= 7.30 1/mole at 24.0°. The isomerization reaction goes to completion within the analytical errors of the techniques used. The reaction rate appeared to be a function of then‐C3H7Br concentration and the aluminium bromide concentration over a wide range of intake ratios:with k = 0.71 1 · mole−1· min−1at 24°.The reaction mechanism is discussed.
Thermochromic and solvochromic behaviour of cobalt (II) chloride solutions in various solvents
Authors: Nieuwpoort W. C. , Wesselink G. A. , van der Wee E. H. A. M. 
Published: September 2010

AbstractIn this paper the spectral behaviour at different temperatures of solutions of anhydrous CoCl2 in water, methanol, ethanol, 1‐propanol, 2‐propanol, and acetone is reported and discussed. The work was initiated by the striking colour changes observed in some of these solvents when the temperature is lowered well below room temperature. The effects are interpreted in terms of octahedral‐tetrahedral configurational changes of solvated Co2+ complexes. A number of earlier observations, which are relevant to the ones reported here and most of which support the interpretation given, are briefly reviewed and discussed.
Chemistry of α‐diazosulfones, VIII: Orthoformic acid derivatives from α‐diazosulfones and sulfenyl chlorides
Authors: Strating J. , Reitsema J. 
Published: September 2010

AbstractAn interesting group of compounds with the general formula R′SO2CH(Cl)SR, is formed by reaction of α‐diazosulfones (R′SO2CHN2) with sulfenyl chlorides (RSCl). Representatives with different kinds of R and R′ groups are described.
Investigations on pesticidal phosphorus compounds V: The structure of the products of the reaction of 3‐alkyl‐5‐anilino‐1,2,4‐triazoles with bis(dimethylamido)phosphoryl chloride
Authors: van den Bos B. G. , Schipperheyn A. , van Deursen F. W. 
Published: September 2010

AbstractThe reaction of bis(dimethylamido)phosphoryl chloride (Bisdi) with 5‐anilino‐1,2,4‐triazoles gave two series of isomers. Their structures were determined and can be characterized by formulae I and II.
Derivatives of benzo‐ and indolo‐quinolizines. III: The stereochemistry of 2‐substituted hexahydro‐2H‐benzo[a]quinolizines and octahydroindolo[2,3‐a]quinolizines
Authors: Gootjes J. , de Roos A. M. , Nauta W. Th. 
Published: September 2010

AbstractTo some of the quinolizine derivatives described earlier (1 and 2) we have been able to assign a cis or trans structure on the strength of a stereoselective synthesis. Infrared spectral data and differences in the rate of dehydrogenation, combined with a study of the conformations possible, allowed such assignment for other compounds in this series.
Fluid phase equilibria in the system polyethylene‐ethylene, II
Authors: Koningsveld R. , Chermin H. A. G. , Diepen G. A. M. 
Published: September 2010

AbstractExperimental data on fluid phase equilibria in the system polyethylene‐supercritical ethylene have been analyzed thermodynamically. The behaviour of the system can be treated as a case of partial miscibility. A quantitative description of this behaviour can be given with the Flory‐Huggins polymer solution theory. A mathematical expression has been derived for the pressure‐temperature projections at constant polymer concentration. Its form resembles a reduced equation of state. An empirical relation was found for the cloud‐point curve, which accounts for its maximum and two inflexions. The expressions obtained permit of extrapolating the experimental data into temperature regions investigated by other authors. The comparison indicates that the different sets of data are consistent.
Enthalpies of solvation of alkali halides in formamide. III.: Structural considerations
Authors: Somsen G. 
Published: September 2010

AbstractExperimental ionic enthalpies of solvation in formamide are converted into absolute enthalpies of solvation by considering the differences between the experimental enthalpies of solvation of cations and anions with identical radii. These differences are caused by the particular charge distribution in the solvent molecule and can be represented as a function of the quadrupole moments of the solvent molecule. The absolute enthalpies of solvation of alkali and halide ions are interpreted in terms of the interaction energy of an ion with six coordinated formamide molecules. In addition, the polarization energy of the solvent beyond the first coordination shell is taken into account.
Messung der magnetischen Susceptibilität von braunsteinhaltigen galvanischen Zellen während der Entladung
Authors: Zeilmaker H. , Drotschmann C. 
Published: September 2010

AbstractMeasurements of the magnetic susceptibility of Leclanché‐type galvanic cells during electric discharges with γ‐ and β‐MnO2 show a different reaction mechanism. Mn2+ is formed during the first part of the discharge of γ‐MnO2. This Mn2+ remains in the MnO2 lattice in solid state. After the catholyte has become alkaline and when a sufficiently great quantity of Mn2+ has been formed in the lattice, a second solid phase will appear. With β‐MnO2, forming of a second solid phase seems to start already after the beginn of the discharge.
Investigations on sterols XXX: Synthesis and stereochemistry of 9β,10α‐isomers of some adrenocortical hormones
Authors: Smit A. , Bakker J. 
Published: September 2010

AbstractThe structure of a microbiological hydroxylation product of 17α,21‐dihydroxy‐9β,10α‐pregn‐4‐ene‐3,20‐dione is found to be 11α,17α,21‐trihydroxy‐9β, 10α‐pregn‐4‐ene‐3,20‐dione. This product is converted into 9β,10α‐cortisone and to 9β,10α‐hydrocortisone. Reduction of the 11‐keto group with lithium aluminium hydride proceeds with the formation of 11β‐hydroxy in minor quantity only. The stereochemistry of the 11‐hydroxyl compounds is discussed on the basis of their nuclear magnetic resonance spectra.
Synthesis of vinyloxypentene and its pyrolysis to aldehyde
Authors: Harkes P. D. 
Published: September 2010

AbstractThe multi‐stage synthesis of vinyloxypentene from 1‐penten‐3‐ol, described by Hurd and Pollack, has been studied. In each reaction step a mixture of a straight‐chain and a branched isomer is formed, the content of the branched compound gradually decreasing. It is highly probable that in the end product no 3‐vinyloxy‐1‐pentene, but only 1‐vinyloxy‐2‐pentene is present, for on pyrolysis of the end product exclusively 3‐ethyl‐4‐pentenal is formed, and no 4‐heptenal as stated in the relevant literature.The synthesis of the model compound 3‐ethyl‐4‐pentenal is described.
The effect of pH upon the solubilities of some inorganic hydroxides in water
Authors: McGowan J. C. 
Published: September 2010

AbstractIonization constants for the dissociations of protons from hydrated metal ions have been estimated and variations with pH of the solubilities of some inorganic oxides and hydroxides in aqueous solutions have been interpreted. It is suggested that the metal ions in solutions of most amphoteric hydroxides exist in two forms at least: there is present either the unhydrated ion and one or more hydrated ions or at least two hydrated ions with different numbers of coordinated groups. When a given ion forms two hydrates, the one with the higher co‐ordination number is the more basic.
Amination of the isomeric dibromopyridines with potassium amide in liquid ammonia
Authors: Streef J. W. , Den Hertog H. J. 
Published: September 2010

AbstractIn connection with an investigation being carried out in our laboratory on the influence of substituents on the course of reactions of halogenopyridines with potassium amide in liquid ammonia, the aminations of 2,3‐, 2,4‐, 2,5‐, 3,4‐ and 3,5‐dibromopyridine and of possible intermediate products, i.e., 4‐amino‐3‐bromopyridine, the 5‐ and 6‐bromo derivatives of 3‐aminopyridine and the 3‐, 4‐ and 5‐bromo derivatives of 2‐aminopyridine, have been studied. End‐products are diaminopyridines or mixtures of these compounds and in some reactions a small amount of 4‐amino‐2‐methylpyrimidine. The last‐mentioned substance is the sole product isolated from the reaction mixture, obtained in the amination of 2,6‐dibromopyridine3,4.The course of the aminations can be explained from what is known on the mechanisms of the aminations of the isomeric monobromopyridines and the mode of addition of ammonia to the triple bond in 3‐ and 4‐substituted benzynes. For the formation of 4‐amino‐2‐methylpyrimidine from 2,3‐, 2,4‐ and 2,5‐dibromopyridine a mechanism is suggested which is analogous to that assumed for the formation of that substance from 2,6‐dibromopyridine3,4.
The reaction mechanism of the acid‐catalysed autoxidation of xanthene to xanthylium ion
Authors: ter Borg A. P. , Gersmann H. R. , Bickel A. F. 
Published: September 2010

AbstractThis paper describes an investigation into the kinetics of the autoxidation of xanthene to xanthylium ion and hydrogen peroxide in a perchloric acid/acetic acid mixture at 20°. Apart from acid catalysis, the reaction also shows the characteristics of a free‐radical chain autoxidation. In the mechanism devised to account for the results the key feature is hydrogen abstraction by a protonated peroxy radical with simultaneous production of the stable xanthylium ion:
\documentclass{article}\pagestyle{empty}\begin{document}\[{\rm RH + RO}_{\rm 2}{\rm H}\cdot^\oplus\to{\rm R}^\oplus+{\rm H}_{\rm 2}{\rm O}_{\rm 2}+{\rm R}\]\end{document}
Derivatives of benzo‐ and indolo‐quinolizines IV: Synthesis of some 1‐ or 3‐substituted hexahydro‐2H‐benzo[a]‐quinolizines and octahydroindolo[2,3‐a]quinolizines
Authors: Gootjes J. , Nauta W. Th. 
Published: September 2010

AbstractThe preparation of some derivatives of 1,3,4,6,7,1 1b‐hexahydro‐9,10‐dimethoxy‐2H‐benzo[a]quinolizine and 1,2,3,4,6,7,12,12b‐octahydroindolo‐[2,3‐a]quinolizine substituted with two alkyl groups, either in the 1‐ or the 3‐position is described. Two reaction routes were followed for each of the two types of compounds and some of the numerous intermediates have been isolated.
Conformation of non‐aromatic ring compounds XXIX: Conformation and pseudorotation intrans‐1,2‐dihalogenocyclopentanes
Authors: Altona C. , Buys H. R. , Havinga E. 
Published: September 2010

AbstractThe relative energies of the pseudorotation conformations oftrans‐1,2‐dihalogenocyclopentanes are evaluated excluding dipole‐dipole interactions. The most stable form corresponds to the half‐chair model with the halogen atoms diaxally disposed about the “puckered” carbon‐carbon bond.
Studies in transition metal chemistry. Part VI: Soluble Ziegler‐type catalysts based on vanadium. Part II
Authors: de Liefde Meijer H. J. , van den Hurk J. W. G. , van der Kerk G. J. M. 
Published: September 2010

AbstractSpectrophotometric measurements in the visible region on soluble catalyst systems prepared from (i) vanadium tetrachloride, aluminium bromide and tetraphenyltin and (ii) vanadium tetrachloride or vanadium oxytrichloride and ethylaluminium dihalides are reported. The formation of hydrocarbon‐soluble inorganic vanadium/aluminium halide complexes containing the transition metal in the tetra‐, tri‐ and di‐valent oxidation state is described and their absorption spectra are recorded. By means of these spectra it is shown that all catalyst systems contain analogous vanadium species, viz. complexes of divalent vanadium in which the transition metal is surrounded octahedrally by halogen atoms only. Evidence is given for the view that organic groups are attached to the aluminium site of the complexes. The structure of the catalytically active species in these systems is discussed.
Acid‐Catalyzed hydrolysis of benzoylphenyldiazomethane: Short communication
Authors: Engberts J. B. F. N. , Bosch N. F. , Zwanenburg B. 
Published: September 2010

AbstractKinetic measurements show that in acidic media the hydrolysis of benzoyl‐phenyldiazomethane is generally acid‐catalyzed. A mechanism for this reaction is proposed. In neutral solutions a different mechanism operates.
Nuclear magnetic resonance studies in coordination chemistry. I: Structure and conformational rearrangements of π‐allyl complexes containing group‐V donor ligands
Authors: Vrieze K. , Maclean C. , Cossee P. , Hilbers C. W. 
Published: September 2010

AbstractNuclear magnetic resonance has been employed to investigate the structure of the complexes (π‐allyl) PdCl(L) (L = phosphine, Ph3As, Ph3Sb) and the conformational rearrangements of the allyl group in these compounds as affected by the ligand, the ligand‐to‐metal ration and the temperature (in CDCl3).Several types of rearrangement were observed, depending on the choice of the variables mentioned above. At low temperatures a short‐lived σ‐allyl intermediate was found in the case of the phosphines only, whereas at higher temperatures rotation of the π‐allyl group was inferred for all the ligands. At very high temperatures and high ligand‐to‐metal ratios a σ‐allyl group had to be postulated to explain the NMR spectra, which are analogous to those of σ‐allyl‐magnesium halide compounds.A molecular orbital description has been used to rationalize some of the experimental results.
On the mechanism of cis‐ligand insertion
Authors: Cossee P. 
Published: September 2010

AbstractFor reactions of the type magnified image L‐O, generally called “cis‐ligand insertion”, there is increasing experimental evidence that the group<//UEQN> Q migrates. The present paper gives a theoretical analysis of this rearrangement, which is illustrated by the specific example of the growth reaction in Ziegler polymerizations of a‐olefins:magnified imageAs a first approximation to the reaction path the angular vibrabtion of R is analysed from a quantum‐mechanical point of view, showing the role that d orbitals in transition‐metal compounds play in the migration of alkyl groups to π‐bonded olefins.It appears that the migrating ligands finds a suitable combination of orbitals to remain bonded to the complex all along the reaction coordinate.