bluuebunny/crossref_metadata_2025_split huggingface dataset:
La Réaction de L'Anhydride Sulfureux et du Dioxyde de Sélénium sur le Diphényl‐Diazomethane . Propriétés du groupe sulfonyle XXXI
Authors: Kloosterziel H. , Backer H. J. 
Published: September 2010

AbstractLe diphényldiazométhane réagissant avec SO2 fournit la tétraphényléthènesulfone, qui, par l'intermédaire d'un radical bivalent, subit un élargissement de l'anneau sulfonique en donnant naissance, selon le solvant, soit au 1,1,3‐triphényl‐1,7a‐dihydro‐isothionaphtène‐2,2‐dioxyde jaune (III), soit au 1,1,3‐triphényl‐1,3‐dihydro‐isothionaphtène‐2,2‐dioxyde (IV) incolore. La décomposition thermique de ces deux sulfones (III, IV) conduit, avec élimination de SO2, au 9,9‐diphényl‐9,10‐dihydro‐anthracène (V) et au 9,10‐diphényl‐9,10‐dihydro‐anthracène (XIII).
Electrochemical behaviour of ion‐exchanging substances.: VI. potential measurements on plant roots and the amphoteric nature of the root substance
Authors: Vervelde G. J. , Tendeloo H. J. C. 
Published: September 2010

AbstractPotentials measured on plant roots in media of varying acidity reverse their sign at a certain pH usually lying in or near the range 3 to 3.5. The value of this pH depends on the plant species. The reversal is explained by the amphoteric character of the root substance. If the root substance carries more dissociated acidoid than dissociated basoid groups, the root potential, pictured as a membrane potential in a Donnan system, will be negative. If there is a surplus of basoid dissociated groups, the potential will be positive. In the intermediate case, where equal numbers of both groups are present, there is no potential because the conditions for a Donnan system are absent. Quantitatively, the electrical behaviour of the amphoteric root substance can be satisfactorily described by assuming a linear relationship between its net acid‐ or base‐binding capacity and the pH.
The Hofmann degradation of 4‐hydroxy‐phthalimide
Authors: van der Stelt C. , Suurmond B. G. , Nauta W. Th. 
Published: September 2010

AbstractAccording to Rodionow and Fedorowa1), Hofmann degradation of 4‐hydroxy‐phthalimide yields 2‐amino‐4‐hydroxy‐benzoic acid. This has been shown to be incorrect. Only 2‐amino‐5‐hydroxy‐benzoic acid could be isolated from the reaction mixture. The spectra of both the acids mentioned were measured, and a few derivatives were prepared.
The hydrolysis of methylene diurea
Authors: de Jong J. I. , de Jonge J. 
Published: September 2010

AbstractThe hydrolysis of methylene diurea giving urea and monomethylolurea was found to be a monomolecular reaction. The rate of the reaction is directly proportional to the hydrogen ion concentration in the pH range measured (3‐5) and independent of the buffer concentration. The activation energy appeared to be 19.5 kcal.Generally, the reaction of an amidomethylol group with an amide group leading to the formation of a methylene bridge between urea fragments, will be a reversible reaction. The rates of both the forward and the reverse reactions are proportional to the hydrogen ion concentration.
The reaction of methylene diurea with formaldehyde
Authors: de Jong J. I. , de Jonge J. 
Published: September 2010

AbstractThe reaction of methylene diurea with formaldehyde showed a close resemblance to the previously studied reaction of urea and formaldehyde1), i.e. the reaction appeared to be bimolecular and the rates were found to be directly proportional to the concentration of hydroxyl ions while further an influence of the buffer concentration on the rates was observed. Obviously the reaction is subject to a general acid and/or base catalysis. The activation energy appeared to be about 15 kcal/mol. The values for the rate constants were almost the same as were found for the reaction between urea and formaldehyde.
Rayonne‐viscose ‐ role physico‐chimique des bains de regeneration
Authors: Pariaud Jean‐Charles , Ferrier Jean 
Published: September 2010

AbstractL'influence des concentrations des bains acides, sur le processus de régénération de la cellulose à partir de la viscose a été éxaminée. La méthode statique employée, en dehors de la filature, est basée sur la mesure de L'épaisseur de la couronne de cellulose, apparaissant lorsqu'on trempe un cylindre de viscose dans ces bains. On propose une interprétation du phénomène.
Etude physico‐chimique de la vagotonine: I. Électrophorèse
Authors: Michel G. F. 
Published: September 2010

AbstractL'hétérogénéité de la vagotonine a été signalée par quelques auteurs. Nous avons étudié le comportement de cette substance et des différentes fractions isolées par précipitation saline, à L'électrophorèse et à L'ultracentrifugation.
On the theory of aromatic substitution: I. A theoretical treatment of the effect of poles and dipoles on the substitution type
Authors: Sixma F. L. J. 
Published: September 2010

AbstractThe method previously described This is the second of a series of communications on the influence of substituents on the reactivity of aromatic compounds. For the first communication cf: F. L. J. Sixma, J. Chem. Phys. 19, 1209 (1951).
for calculating the influence of the electric field of a substituent (inductive effect) on the energy content of the intermediate complex of substitution reactions in the benzene nucleus, proceeding from the known values of dipole moments, bond lengths and valency angles, is further elaborated.The theory is tested on the experimental results for electrophilic substitution reactions. The agreement between calculated and experimental values for the percentage meta‐substitution is very satisfactory for those substituents which show little or no resonance interaction (E‐effect) with the pentadienate cation.
The reactivities of alpha methylenic groups towards free radicals: III. Steric effects in tetralin, indan and dihydroanthracene derivatives
Authors: Kooyman E. C. , Strang A. 
Published: September 2010

AbstractThe relative reactivities towards trichloromethyl radicals were determined for a number of tetralin, indan and dihydroanthracene homologues, using the retardation method described previously 1) 2).As in the case of alkylbenzenes 2), several of the hydrocarbons showed marked decreases in reactivity compared with the additive values. The effects are again attributed to steric interference with the most favourable transition state configuration. They were found to become increasingly important in the order (1‐methylindan, hexahydrofluorene), 1,4,7‐trimethylindan, (cumene, 1‐methyltetralin, 9,10‐dimethyl‐9,10‐dihydroanthracene), 9,10‐diisopropyl‐9,10‐dihydroanthracene, (o‐cymene, hexaethylbenzene, 1,2,4,5‐tetraisopropylbenzene).The magnitudes of the effects are discussed on the basis of the calculated distances between the centres of the interfering groups in the absence of steric repulsion. This leads to an estimate of the effective methyl radius of about 1.5 Å at angles of approach of about 80°, i.e. a value considerably smaller than the Van der Waals radius (2.0 Å).
Researches on heterogeneous redox‐systems
Authors: Tendeloo H. J. C. , de Vries T. J. 
Published: September 2010

AbstractMeasurements on the redox‐system methylene blue‐leuco‐base of methylene blue in water and the same system containing active carbon lead to the conclusion that adsorbed methylene blue shows markedly different properties. The reduction of adsorbed methylene blue by TiCl3 is hindered.
Phosphatide acids and derivatives: II ). Synthesis of glycerophosphatidic acids, starting from diglycerides
Authors: Uhlenbroek J. H. , Verkade P. E. 
Published: September 2010

AbstractThe present paper describes the synthesis of the seven possible glycerophosphatidic acids (formulae IX‐XII) containing palmitic and/or stearic acid as component acids, by the hydrogenolysis of the corresponding diphenyl esters with hydrogen in the presence of a platinum/active carbon catalyst. The diphenyl esters are obtained by the action of diphenyl chlorophosphate on the monoacid and diacid αβ‐ and αγ‐diglycerides in the presence of an excess of pyridine.Some properties of the glycerophosphatidic acid diphenyl esters and the glycerophosphatidic acids are described.
Stability of oil‐in‐water emulsions I: The electrical double layer at the oil‐water interface
Authors: van den Tempel M. 
Published: September 2010

AbstractThe electrostatic interaction between charged oil globules in water is determined by the potential drop at the aqueous side of the interface. This potential drop is, under the conditions of the present investigation, practically entirely determined by the amount of adsorbed soap ions and the electrolyte concentration in the aqueous phase. A model is described according to which the charge in the diffuse layer is compensated by the charge of the adsorbed soap anions minus the charge of the counter‐ions situated between the ionic heads of the adsorbed soap ions. The capacity of the double layer in the oil phase may be neglected.The amount of adsorbed soap ions has been determined by measuring the dependency of the interfacial tension on the soap concentration, followed by application of the Gibbs adsorption isotherm. The potential drop at the aqueous side of the interface has been calculated; it was found to be practically independent on the soap concentration in the range of concentrations investigated. The potential drop is decreased by increasing the salt concentration; the effect of an addition of salt on the potential drop is strongly dependent on the valency of the counter ions.Determination of the zeta‐potential by measurement of electrophoretic mobility of oil droplets indicates that the values of the surface potential as calculated are of the right order of magnitude.
An exact vapour pressure equation
Authors: Gottschal A. J. , Korvezee A. E. 
Published: September 2010

AbstractIn this paper a general vapour pressure equation is derived from the thermodynamic equilibrium condition. For pressures under or slightly over one atmosphere, where the equation of statepv = RT + Bpis valid for the vapour, three correction terms must be added to log p to obtain (log p)corr = −A/T + D. The three correction terms can be calculated from precise specific heat and density data for either phase.The variation of the heat of vaporization with temperature is shown to depend on the same data.
On the mutual stability relationship of MeAn complexes consisting of a metal ion Me and a ligand A in aqueous solution, for consecutive values of n
Authors: van Panthaleon van Eck C. L. 
Published: September 2010

AbstractThe stability of MeAn complexes formed by a metal ion Me and a ligand A in aqueous solution, as a function of consecutive n values is discussed. Literature data constitute the basis of this discussion.For quite a number of systems it is possible to draw up an equation accurately correlating the stability of the MeAn complex with that of the MeA1 complex and with the n value.
Steric hindrance of resonance in a substituted phenylmethylsulphone: (Properties of the sulphonyl group XXXVIII)
Authors: Kloosterziel H. , Backer H. J. 
Published: September 2010

AbstractN‐acetyl‐4‐methylsulphonyl‐2,6‐xylidine (I) has been prepared by the convenient method used before, involving thiocyanation of 2,6‐xylidine and reduction of the thiocyano group with LiAlH4, followed by methylation and subsequent oxidation of N‐acetyl‐4‐methylmercapto‐2,6‐xylidine to the corresponding sulphone. The latter compound (I) has an U.V. spectrum intermediate between those of phenylmethylsulphone and N‐acetyl‐p‐methylsulphonylaniline, indicating that the extended resonance is sterically hindered.
Synthesis of some aliphatic β‐amino‐dicarboxylic acids
Authors: Gootjes J. , Nauta W. Th. 
Published: September 2010

AbstractThree β‐amino‐dicarboxylic acids were prepared by reduction of the corresponding ethyl β‐oxo‐dicarboxylate acetylhydrazones. The melting point and the tuberculostatic activity of β‐amino‐pimelic acid are not in accordance with the data found by Romeo for a compound obtained by hydrogenation of p‐amino‐salicylic acid, which seemed to be β‐amino‐pimelic acid.
An investigation as to the type of particles occurring in concentrated solutions of electrolytes in relation to the hydration of the ions
Authors: van Ruyven B. H. 
Published: September 2010

AbstractIn this communication we make an investigation in the domain of concentrated electrolytic solutions on a larger scale and of a more profound kind than was possible in 19371). Principally use is made of depressions of vapour pressure determined by Tammann, if possible up to a weight‐normal concentration (n ω) = 10.Raoult's law (in the domain of vapour pressures), combined with ideas of Arrhenius, leads to the calculation of degrees of ionisation. The values found necessitate the assumption of hydration of ions or of ion pairs and ions. Remy determined ion hydrations by a direct method. The literature on the subject was difficult to survey and not very convincing2).Thus various ideas lead to the study of footnote 1 and of this communication
Can the assumption of ion hydration cooperate in the explanation of the anomalies acknowledged by Arrhenius himself?
Can ion hydrations be calculated in the above way?
Can further insight be obtained that way into the nature of concentrated electrolytic solutions?
We began our exploration at the time without taking into account the effect of forces acting between the ions on the observed depressions of vapour pressure because their total effect could not be calculated. We have now worked up all Tammann's data and have not found a single electrolyte which gives exclusively naked ions. This did not make that total effect any clearer. We had to organize this expedition in the same way, in the footsteps of my former teacher the late Prof. M. de Haas, who always insisted on attempting to arrive at “Knowledge through Measurement” (“door meten tot weten”) and mindful of the words of Debye3) and of Remy2). The results have indeed often surprised us and spurred us to continue.
Synthese einiger optisch aktiver α,α′‐Iminosäuren: Untersuchungen in Beziehung zu Eiweissproblemen. I
Authors: Kögl F. , de Flines J. 
Published: September 2010

AbstractDie vier Stereoisomeren der von Alanin und Asparaginsäure abgeleiteten α,α′‐Imino‐propionsäure‐bernsteinsäure und jene der von Alanin und Glutaminsäure abgeleiteten α,α′‐Imino‐propionsäure‐glutarsäure wurden dargestellt und mit Hilfe eines Kationenaustauschers mit guten Ausbeuten in kristallisierter Form erhalten.Aus L‐Glutaminsäure‐1,2‐C14‐2,3‐D‐N15 und D‐α‐Brompropionsäure wurde L‐α‐L‐α′‐Imino‐propionsäure‐glutarsäure synthetisiert, die im Glutaminsaure‐Rest mit den drei Isotopen markiert war.
Synthesis, refractometric constants, and some other physical properties of a homologous series of branched alkenes
Authors: Schuhmacher J. P. , Wibaut J. P. 
Published: September 2010

AbstractThe preparation of eleven terms of the homologous series of the 2‐methyl‐1‐alkenes (2‐methyl‐α‐alkenes) is described. The purity of the preparations obtained was determined by measuring the melting curves. The densities and refractive indices of the synthesized compounds at 20° C and 25° C were determined; the measurements of the refractive indices were carried out at nine wave‐lengths. From the values of the densities and the refractive indices the molecular refractions were determined according to the formula of Lorentz‐Lorenz. By the method of the least squares we derived, with the aid of these data, the values of the refraction equivalent of the CH2‐group and the increment of the double bond. The densities and refractive indices determined experimentally appeared to correspond excellently with values calculated from empirical formulae. Besides densities and refractive indices the final melting points, the boiling points and the infra‐red spectra of the synthesized compounds were determined.
Studies on the hill reaction (II)
Authors: Wessels J. S. C. , Havinga E. 
Published: September 2010

AbstractThe influence of the presence of oxygen on the Hill reaction has been investigated by redox potential measurements.A very simple reaction scheme, implying primary formation of a specific reductant reacting subsequently with the oxidant added, seems to fit kinetical and other data of the reaction.Some of the results of investigations on the influence of inhibitors and biochemically important substances are reported and discussed; possible causes for the discrepancies in the literature concerned with the action of inhibitors are indicated.
Steric effects on mesomerism: XII). On the effective size of methyl(ene) groups, especially in ortho‐xylene derivatives
Authors: van Helden R. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractThe phenomenon mentioned in an earlier paper,viz.that a methyl group inortho‐xylene derivatives may behave as a larger substituent than the methyl group in comparablepara‐xylene or toluene derivatives, has been investigated more in detail with the aid of deacylation rates, ultra‐violet absorption spectra, molecular refractions, and basic strengths. The phenomenonper sehas been confirmed by this work. Naturally, however, it does not always manifest itself to the same degree; various factors play their part in this respect.On the strength of the data collected, the order of steric effects of methyl (ene) groups found byArnoldand co‐workers has to be modified as follows: CH2(in o‐xylyl) > CH2(in a 6‐membered ring) > CH2(in tolyl) > CH2(in a 5‐membered ring).
Isomerism in the 2,4‐dinitrophenylhydrazones of α‐keto‐acid esters
Authors: van Duin H. 
Published: September 2010

AbstractThe 2,4‐dinitrophenylhydrazones of α‐keto‐acid esters occur in isomeric forms, here called α‐ and β‐isomers. The α‐isomers differ from the β‐isomers in melting point, UV absorption, and retention volume in partition chromatography. In the presence of hydrogen ions or on irradiation with UV light, these isomers yield equilibrium mixtures in which, at any rate after irradiation, the β‐isomers greatly predominate. The α‐ and β‐isomers of pyruvic esters of homologous normal aliphatic alcohols both form a homologous series, but it is possible to separate not too complicated mixtures of these alcohols from C1 to C18, to identify the individual terms, and to determine their amounts by UV absorption measurements. Finally, some aspects of isomerism in hydrazones and the possible structure of the isolated α‐ and β‐isomers are discussed. For the β‐isomers an extrastabilized syn structure is probable.
Light‐scattering by a number of solvents, in conjunction with data on solutions of Ludox, saccharose‐octa‐acetate, and polystyrene
Authors: Trap H. J. L. , Hermans J. J. 
Published: September 2010

AbstractA light‐scattering apparatus is described. It is calibrated by means of Ludox solutions, whose absolute turbidities are determined in transmission measurements. A check on the method is made with solutions of sucrose octa‐acetate in methanol and of the international polystyrene sample 2 (2‐1‐49) in butanone and in toluene.Finally, the turbidities of various solvents are reported, and compared with values quoted from the literature (Sect. 7).
Radio‐active exchange studies on the transformations of the hydrates of CaSO4.
Authors: Ketelaar J. A. A. , Heijmann D. 
Published: September 2010

AbstractThe exchange of sulphate ions labelled with sulphur 35 in solution with solid CaSO4 · 2H2O and CaSO4 · 1/2 H2O was studied in saturated solutions at 80° C containing orthophosphoric acid of different concentrations. When the solid phase did not undergo transformation, no appreciable exchange was observed. However, when a transformation into a different modification took place, this was accompanied by total exchange. This indicates that the transformationsmagnified imageall take place by the growth of nuclei of the new phase from the solution, thus excluding a zeolithic nature of these phase changes as suggested.
The effect of surface‐active compounds on the polarographic waves of oxygen and zinc and the electrocapillary curve of mercury
Authors: Bonting Sj. L. , Aussen B. S. 
Published: September 2010

AbstractThe accidental observation of a pronounced shift of the half‐wave potential of oxygen in bacterial media containing small amounts of tween‐80, a surface‐active agent, caused us to investigate the effect of surface‐active agents on the polarographic wave in more detail.As a result of our studying simultaneously the effects on the electrocapillary curve of mercury, this behaviour could be attributed to the formation of an adsorption layer on the mercury surface. The different effects of different types of surface‐active agents on this curve can be understood from their chemical nature.
Studies on tautomerism III: The nitrosation products of meta‐chlorophenol
Authors: Kraaijeveld A. , Havinga E. 
Published: September 2010

AbstractAs was first reported by Hodgson and his collaborators3) 4), the nitrosation of meta‐chlorophenol gives two products depending on the conditions, the one having a melting point of approx. 142° and the other melting at 184°. The present and the subsequent paper provide experimental evidence showing that of these two “tautomers”, which have been the subject of extensive studies in the past, the low melting compound (m.p. 142°) is an addition complex of equimolecular amounts of the high melting one (3‐chloroquinone‐4‐oxime or 3‐chloro‐4‐nitrosophenol3), m.p. 184°) with 3‐chlorobenzene‐6‐diazo‐oxide (m.p. 124°); the components could be separated and identified by means of chromatography. This conception explains the unorthodox properties of the substance, reported by several authors, e.g. the products of its chemical reactions are derived either from the diazo‐oxide or from the quinone monoxime, the latter reacting according to either of its tautomeric forms5).
Studies on tautomerism IV: The complexes of 3‐halogenobenzene‐6‐diazo‐oxides with quinone monoximes (nitrosophenols) and some other complexes
Authors: Kraaijeveld A. , Havinga E. 
Published: September 2010

AbstractThe nature of the product of m.p. 142°, formed during the nitrosation of meta‐chlorophenol in neutral or weakly acidic medium, has been investigated. The view that it should be considered as a complex compound of equimolecular amounts of 3‐chlorobenzoquinone‐4‐oxime (3‐chloro‐4‐nitrosophenol) and 3‐chlorobenzene‐6‐diazo‐oxide is supported by the analytical data, by its formation from the components, by its behaviour during crystallization and by X‐ray data. Moreover, many discrepancies in the literature find an obvious explanation and there are no longer difficulties such as arise in explaining the chemical behaviour of the substance when regarded as a tautomer of the 3‐chloroquinone‐monoxime (m.p. 184°). One of the possible reactions leading to the formation of the diazo‐oxide is the diazotization of the corresponding nitroso‐compound. The presence of 3‐chlorobenzene‐4‐diazo‐oxide amongst the nitrosation products of meta‐chlorophenol is demonstrated. The nitrosation of m‐bromophenol is shown to give products completely analogous to the chloro‐compounds. Finally, the formation of some characteristic complexes, in which diazo‐oxides take part, are discussed. The conclusion is reached that the 3‐halogeno‐4‐nitrosophenols (3‐halogeno‐benzoquinone‐4‐oximes) now fit in smoothly with the other nitrosophenols.
Additions nucleophiles au bis‐tertiobutylsulfonyl‐acétylène I: (Propriétés du groupe sulfonyle XLI)
Authors: Backer H. J. , Strating J. 
Published: September 2010

AbstractLe bis‐tertiobutylsulfonyl‐acétylène présente une remarquable tendance à l'addition de réactifs nucléophiles. Les alcools se fixent sans catalyseur et les mercaptannes sont encore plus actifs. Pour les phénols la présence d'un phénolate est de rigueur.