bluuebunny/crossref_metadata_2025_split huggingface dataset:
Les Pinacols de la p.Méthylacétophénone et la Sulfone du 3,4‐di‐p. Tolylthiophène
Authors: Backer H. J. , Stevens W. , van der Bij J. R. 
Published: September 2010

AbstractAyant besoin du 2,3‐di‐p‐tolylbutadiène, les auteurs ont préparé d'après plusieurs procédés le pinacol de la p‐méthylacétophènone. L'addition d'un excès d'iodure de méthylmagnésium à la p‐tolile, a donné naissance à trois produits qui diffèrent par les propriétés cristallographiques et par le point de fusion.Deux de ces produits (136‐137° et 134.5‐135°) sont des diols stéréoisomères qui, oxydés par le tétracétate plombique, présentent des constantes de vitesse tout‐à‐fait différentes. Le troisième produit, fondant à 93‐94°, se comporte pendant l'oxydation comme un mélange; c'est une combinaison moléculaire du diol 134.5–135° (1 mol.) et d'un cétol fusible à 80‐81° (2 mol.), qui s'est formé par addition d'une seule molécule du composé magnésien à la p‐tolile.La déshydratation du pinacol 136‐137° conduit au 2,3‐di‐p‐tolylbutadiène qui, additionnè d'anhydride sulfureux, fournit la sulfone cyclique. La méme sulfone prend naissance par hydrogénation partielle de la sulfone incolore de 2,3‐di‐p‐tolylthiophène.
On the determination of the number of intermediate stages through which a chemical reaction passes
Authors: Kreulen D. J. W. , ter Horst D. Th. J. 
Published: September 2010

AbstractIn order to obtain an insight into the course of reactions it is important to know whether the final products are formed directly or by way of intermediate products. A method is developed in the following which makes it possible to obtain this information in the case of slow reactions.From the relation existing between the concentration of the substance formed and the reaction time, it may be concluded whether the substance in question is formed directly or by one or more intermediate stages.In the first part the general method is dealt with on a mathematical basis. The second part is devoted to several examples, whereby reactions are discussed not only in a one‐phase system (liquid) but also in a two‐phase system (solid‐gas and liquid‐gas).
The preparation of unsaturated hydrocarbons by the thermal decomposition of acetates : Second communication
Authors: van Pelt A. J. , Wibaut J. P. 
Published: September 2010

AbstractThe thermal decomposition of acetic acid esters is used as a method for the preparation of unsaturated hydrocarbons of different types. Auxiliary reactions, with the formation of isomers of the hydrocarbons, do not occur, so that this method is very suitable for the preparation of unsaturated hydrocarbons, in large as well as small quantities. The yields with respect to the acetate vary from 60 to 90 per cent.
The density and sorptive capacity of some samples of cotton, silk and wool
Authors: Heertjes P. M. 
Published: September 2010

AbstractBy means of the determination of the true densities in helium and the apparent densities in air, hydrogen, benzene and water of some samples of wool, the dyeing process of wool with acid and basic dyes and the felting process of wool are studied, and some conclusions with regard to these processes are drawn.Moreover the sorptive capacities of wool for air and hydrogen are calculated, and the nature of these sorption phenomena is discussed.
The refractometric constants of 3, 3‐dimethylbutene‐1
Authors: Wibaut J. P. , Gitsels H. L. P. 
Published: September 2010

AbstractUsing a pure sample of 3.3‐dimethyl‐butene‐1, we have determined the refractive indices at different wave lengths and the specific gravity. From these data the refractometric constants of this hydrocarbon have been calculated. magnified imagehas been examined by a number of investigators; the values given for specific gravity and refractive index differ, as shown by table I, in which we have collected the relevant literature data.
Die Quantitative Bestimmung des Mangans im Weidegras
Authors: de Wael J. 
Published: September 2010

AbstractBei der Bestimmung des Mangangehaltes von Weidegras gibt die Methode von Richards unzuverlässige Ergebnisse. Wir konnten zeigen, dass die nachfolgenden Fehlerquellen bestehen:
Das Abrauchen mit Schwefelsäure veranlasst zu niedrige Resultate.
Die Asche des Grases schliesst Mangan ein.
Es gelang uns die genannte Fehlerquellen zu beseitigen, nämlich durch Ersetzen der Schwefelsäure durch Phosphorsäure. Bei Anwendung dieser Säure werden viel höhere und besser reproduzierbare Werte für den Mangangehalt des Grases gefunden.
Über das Reine Silberbromidsol II
Authors: Basiński A. 
Published: September 2010

AbstractEs werden elektrometrische Messungen an reinen negativen Silberbromidsolen beschrieben. Auf Grund von Titrationen mit Silbernitrat konnte der Ladungsnullpunkt des Silberbromids auf eine Bromionenaktivität von 2‐4 × 10−7 bestimmt werden, also ein wenig nach der Silberseite vom Aequivalenzpunkt verschoben. Durch Hinzufügen von K+, Ba++, La+++ und Th++++ Salze, sowie von einem Salz eines 4‐wertigen komplexen Kations wird die Bromionenaktivität im Sinne einer Entladung (Herabsetzung des ξ Potentials) geändert, wahrend die 6‐ und 9‐wertigen komplexen Kationen zu einer Umladung im Stande sind.Bei der Messungen mit 6‐wertigem Hexolsalz hat sich herausgestellt, dass die Potentialdifferenz zwischen einer Ag‐AgBr‐Elektrode und einer Lösung von Hexolsalz stark durch Rühren beeinflusst wird. Es wurde der Einfluss von Ag+, Bi− und Hexosalzkonzentration auf diesen „Rühreffekt”︁ bestimmt.
Untersuchungen über Pyrrolderivate: 5. Mitteilung
Authors: Rinkes I. J. 
Published: September 2010

AbstractTerentjew und TschelinzewA. P. Terentjew und W. W. Tschelinzew, 58, 69 (1925).
behaupten, dass bei Dijodierung des 2‐Acetylpyrrols 2‐Acetyl‐3.4‐dijodpyrrol entsteht, da diese Verbindung bei Oxydation mit Salpetersäure Dijodmaleinimid liefert. Es gelang mir zu zeigen, dass dieses Argument wertlos ist und dass nach der Theorie 2‐Acetyl‐4.5‐dijodpyrrol zu erwarten ist.Weiter konnte ich zeigen, dass die durch Dibromierung des 2‐Pyrrol‐carbonsäure‐methylesters entstehende Verbindung die Bromatome wahrscheinlich an den Stellen 4 und 5 hat weil das Produkt nicht identisch war mit dem von mir bereiteten 3.4‐Dibrom‐2‐pyrrolcarbonsäure‐methylester.
Die Dampfspannung von Gesättigten NH4NO3‐Lösungen
Authors: Dingemans P. 
Published: September 2010

AbstractDie Dampfspannung von gesättigten, wässrigen Lösungen von NH4NO3 wurde von 10° C an bis zum Schmelzpunkt des Salzes (169° C) gemessen. Es zeigte sich, dass die gefundene Kurve zwei Maxima besitzt, eine Tatsache, die bislang für gesättigte, wässrige Lösungen noch niemals gefunden worden ist.Eine theoretische Betrachtung und eine Besprechung der Bedingungen für das Auftreten von 2 Maxima wird gegeben.
Solvent and dissociating power of chlorinated hydrocarbons: Part III. (Experiments)
Authors: van Braam Houckgeest J. P. W. A. 
Published: September 2010

AbstractIn order to estimate the value of the theory and the calculations carried out in Parts IJ. P. W. A. van Braam Houckgeest, Rec. trav. chim. 59, 560 (1940), 60, 65 (1941).
and II2 experiments on the conductivity of solutions of tetra‐alkylammonium halides in chlorinated hydrocarbons and their solubility in these solvents were performed. It appears that the calculations are only accurate enough to account for very marked differences. The solubilities and degrees of dissociation of one electrolyte in a series of solvents correspond better with the theory than the solubilities of a series of electrolytes in one solvent. This is probably because the solvatation energies can be calculated with a greater accuracy than the lattice energies.
The heat of mixing of some chloro‐alkanes with ethyl ether
Authors: Staverman A. J. , Lebbink F. J. 
Published: September 2010

AbstractThe cohesion forces of molecules with an asymmetric distribution of the electrical charge depends on this asymmetry; the dipole moment is not a suitable quantity for the description of cohesion forces, but some other quantity depending on the distance of the charges from the surface.In order to obtain the values of this quantity for a number of molecules, many data on heat of evaporation and heat of mixing are necessary. Therefore we have measured the heat of mixing of chloroform, pentachloroethane and methyl chloroform with ethyl ether at infinite dilution, both of the ether and of the chloro‐alkane. The results confirm the above considerations.
Eine Einfache Methode zur Bestimmung der Diffusionskonstante von Metallen
Authors: van Liempt J. A. M. 
Published: September 2010

AbstractEs wird eine einfache Methode zur Bestimmung der Diffusionskonstante von Metallen entwickelt, nach der ein dünner Draht (Band) des einen Metalls in eine Masse des zweiten unedleren Metalls metallkeramisch eingebettet und die Erhitzungsdauer und ‐temperatur festgestellt wird, nachdem die Diffusion so weit fortgeschritten ist, dass die Resistenzgrenze im ganzen Draht‐(Band) querschnitt gerade erreicht ist.
On the influence of solvent and temperature on the speed of oxidation of some organic substances by chromic acid. IV
Authors: Snethlage H. C. S. 
Published: September 2010

AbstractThe velocity of the reaction between adipic acid and chromic acid has been measured in mixtures of sulphuric acid and water containing from 50% to 95.9% sulph. ac. at temperatures between 313.1° and 353.1° K. The formula for a bimolecular reaction does not hold. Temperature coefficients were found to be practically independent of the degree of decomposition of the adipic acid for the first 20‐30% of the reaction in dilute sulph. ac., and to change slowly in 80% and 95.9% sulph. ac. They do not obey the formula of Arrhenius and their relation to the composition of the solvent is of the same nature as in the case of succinic acid.
De la Composition des Cristaux Mixtes D'Un Système Binaire
Authors: Korvezee Mlle A.‐E. , Scheffer M. F.‐E.‐C. 
Published: September 2010

AbstractNous avons calculé la composition moyenne d'un cristal mixte, qui se sépare par refroidissement d'une solution binaire, à condition que la diffusion dans la phase solide soit nulle. La courbe qui représente la composition moyenne des cristaux en fonction de la température du système se termine par une tangente horizontale ou verticale suivant la valeur limite dxs/dxL au point de solidification du deuxième constituant.Les mêmes calculs s'appliquent aux solutions volatiles binaires qu'on distille sans rectification. La courbe calculée se rapporte alors à la composition du distillat.
The crystal structure of the ice‐like form of sulphur trioxide (γ‐modification)
Authors: Westrik R. , Mac Gillavry C. H. 
Published: September 2010

AbstractThe crystal structure of the γ‐modification of sulphur trioxide has been completely determined.The cell is orthohombic, with cell constants a = 12.3 Å, b = 10.7 Å and c = 5.3 Å and contains 12 units of SO3; the X‐ray density is 2.29.The structure is a molecule lattice built up of molecules S3O9; a [001] projection is seen in fig. 7, the atomic positions are given on p. 806, 807.The molecule S3O9 contains a puckered (SO)3 ring (fig. 4b), in agreement with the latest results of Raman and infrared investigation.
On the influence of solvent and temperature on the speed of oxidation of some organic substances by chromic acid V.
Authors: Snethlage H. C. S. 
Published: September 2010

AbstractThe velocity of the reaction between formic acid and chromic acid has been measured in mixtures of sulphuric acid and water, containing from 0‐87% sulph. ac. at temperatures between 273° and 353° K.This velocity is nearly proportional to the concentrations of the reactantsIn very dilute sulph. ac. the acceleration caused by this substance is about proportional to its concentration, in more concentrated solutions it is greater. Between 60 and 87% there is an optimum.Between 5 and 60% sulph. ac. the velocity constants at 293° increase to the 33000 fold, they can be calculated from Hammett and Deyrup's acidity function H0 (which is based on measurements with basic indicators at 298° K). At other temperatures the relation of Hammett and Deyrup fails to represent the experimental results. It is supposed that the relative acidity, at least in dilute sulph. ac, changes with the temperature. Between 13.5 and 40% sulph. ac. there exists a simple relation between the composition of the solvent and the velocity of the reaction at any temperature.The temperature coefficients in most solvents used change very little with the temperature, in consequence the formula of Arrhenius does not hold.
Das Fette Oel der Samen von Hesperis Matronalis L.
Authors: Steger Alph. , van Loon J. 
Published: September 2010

AbstractDas fette Oel der Samen von Hesperis matronalis L. gehört zu den trocknenden Oelen und besitzt eine leinölähnliche Zusammensetzung, sodass es als Leinölersatz Verwendung finden kann.
The colour of N,N′‐diethylindigo (on indigo VII)
Authors: van Alphen J. 
Published: September 2010

AbstractIn the solid state N,N′‐diethylindigo forms dark blue needles with a metallic lustre. Its solutions in different solvents are an intense malachite green in colour.Depending on the method of crystallization N,N′‐dibenzylindigo forms dark green to nearly black needles. Its solutions however are the same colour as those of N,N′‐diethylindigo.
A quantitative colorimetric determination of small amounts of trigonelline
Authors: Roggen J. C. 
Published: September 2010

AbstractWhen trigonelline is heated with alkali, methylamine is split off and the remaining dialdehyde, formed by ring opening, is conjugated to aniline in acid medium.A yellow colour appears almost instantly, suitable for colorimetric determination.No turbidities occur, the colour is sufficiently stable in full daylight and 10 γ per ml can be determined with an accuracy of about 5%.
On the influence of solvent and temperature on the speed of oxidation of some organic substances by chromic acid. VI
Authors: Snethlage H. C. S. 
Published: September 2010

AbstractThe velocity of the reaction between malonic acid and chromic acid has been measured in mixtures of sulphuric acid and water containing from 10 to 96.55% sulph. ac. at temperatures between 273.0° and 353.0° K. The formula for a bimolecular reaction does not hold, but the initial velocity is approximately proportional to the concentration of both reactants.In this case also the initial velocity has an optimum between 70 and 96% sulph. ac. Proportionality between acidity (measured colorimetrically) and velocity does not exist, in contrast to the case of the oxidation of formic acid.The temperature coefficients are largely dependent on the composition of the solvent. For most of the solvents used the formula of Arrhenius does not hold, in accordance with what was found for all substances investigated until now (exception in this case: 10 and 20% sulph. ac.).The temperature cofficients and both the parameters of the equation of Arrhenius show a minimum at about 60% sulph. ac., corresponding to what was found with other substances. Between the parameters a close correlation exists.It is supposed that the large changes in the temperature coefficient, which accompany relatively slight changes in the composition of the solvent, are to be ascribed to the presence of solution components whose concentration is dependent on the temperature and does not increase continuously with the increase of the sulph. ac. content of the solvent. These might be the hydrates SO35 aq. and SO33 aq. or an intermediate compound of CrO3, malonic acid and perhaps hydrates. This supposition could also explain the deviations from the equation of Arrhenius.
Produits de Réduction de L'Acide γ‐Anisoyl‐n‐Butyrique, de son Oxime et des Homologues Éthoxy
Authors: van der Zanden J. M. 
Published: September 2010

AbstractPour étudier les qualités physiologiques des produits en question, nous avons préparé les produits décrits ci‐après.Ayant réduit l'acide γ‐anisoyl‐n.butyrique, CH3O. C6H4. CO(CH2)3. COOH, nous avons obtenu la lactone de l'acide δ‐p.méthoxyphényl‐δ‐hydroxy‐nvalérique, magnified image l'acide 5,6‐di‐p‐méthoxyphényl‐5,6‐dihydroxy‐sébacique, magnified image et l'acide δ‐p. méthoxyphényl‐n.valérique, CH3O. C6H4(CH2)4. COOH, décrit dans un mémoire précédentJ. M. van der Zanden, Rec. trav. chim. 60, 292 (1941).
).La réduction de l'oxime nous a donné l'acide δ‐p.méthoxyphényl‐δ‐amino‐nvalérique, CH3O. C6H4. CH(NH2). (CH2)3. COOH. le lactame correspondant. magnified image puis la 2‐anisylpipéridine.magnified imageLes homologues éthoxy ont donné les produits correspondants.
Pseudosymétrie Présentée par les Esters de L'acide Tétrathioorthosilicique
Authors: Klasens H. A. , Backer H. J. 
Published: September 2010

AbstractEn examinant la structure de cristaux à l'aide des rayons Röntgen, on trouve une équivalence complète entre les places qui ont la même chance d'être occupées par des atomes ou des groupes différents. Dans ce cas, on trouve pour la cellule du réseau cristallin des éléments de symétrie qui n'existent pas en réalité, de sorte qu'on attribue aux molécules une symétrie trop élevée. Dès lors, il peut arriver que la symétrie trouvée soit en contradiction avec la composition chimique.Il n'est pas nécessaire ‐ et dans certains cas il est impossible ‐ d'attribuer de telles pseudo‐symétries à une rotation des molécules dans le réseau. Souvent cette pseudo‐symétrie est causée par une repartition statistique des groupes atomaires entre des positions différentes. C'est ce qui se passe dans le cas de quelques esters asymétriques de l'acide tétrathioorthosilique, esters qui sont isomorphes de l'ester tétratertiobutilique.
Determination of nicotinic acid in human blood (I)
Authors: Roggen J. C. 
Published: September 2010

AbstractAfter improving the König BrCN‐reaction and applying it to human blood the following results were obtained. When haemolyzed blood is deproteinized by means of metaphosphoric acid, no cozymase is precipitated, but all of the pyridine compounds remain in the aqueous solution.Probably nicotinamide is then present, but as the amount of nicotinic acid found after hydrolysis is much larger, there must be some other pyridine compound present in blood, which also yields nicotinic acid after hydrolysis.There is strong evidence that the pyridine compound determined after hydrolysis is indeed nicotinic acid.A routine method for the estimation of nicotinic acid in blood is described.
Nitration of the three isomeric N‐cyclohexyl‐N′‐toluyloxamides
Authors: de Vries K. A. 
Published: September 2010

AbstractA description is given of the three isomeric N‐cyclohexyl‐N′‐toluyloxamides and their nitration in anhydrous nitric acid. Upon the nitration of N‐cyclohexyl‐N′‐(4 methylphenyl)‐oxamide the final product was N‐cyclohexylnitro‐N′‐(4‐methylphenyl)‐oxamide, upon the nitration of N‐cyclohexyl‐N′‐(3‐methylphenyl)‐oxamide it was N‐cyclohexyl‐N′‐(2,4,6‐trinitro‐3‐methylphenyl)‐oxamide and upon the nitration of N‐cyclohexyl‐N′‐(2‐methylphenyl)‐oxamide it was a mixture probably of N‐cyclohexylnitro‐N′‐(4,6‐dinitro‐2‐methylphenyl)‐oxamide and N‐cyclohexylnitro‐N′‐(4,6‐dinitro‐2‐methylphenylnitro)‐oxamide.
The determination of carotene in plant material and feces
Authors: van Eekelen M. , Engel Chr. , Bos A. 
Published: September 2010

AbstractIn order to find a quantitative method for determining the carotene content in plant material and feces (for use in physiological resorption experiments) we have worked over again and compared the methods known from various earlier publications. A secondary aim was to find a useful method which may be applied as routine analysis in other laboratories to obtain reproducible and comparable results. None of the known methods proved to be generally applicable, although for some materials they sufficed.The following points were specially studied: 1. The determination of carotene concentration with the aid of the Zeiss Stufenphotometer. The extinction values published in earlier studies have been checked. 2. The separation of carotene from other pigments. This is only possible with adsorbents as aluminium oxide and calcium hydroxide. The losses which usually occur could be eliminated by a slight modification of the adsorption‐elution technique. 3. The extraction of the material. Simple continual extraction with ethyl alcohol in a Berntrop flask gives quantitative results. It is suitable for routine analysis. In the case of grass ensilated with acid, the extraction with alcoholic potassium hydroxide according to Guilbert is necessary. However this method gave no quantitative results with other materials. Results and description of the methods are given below.
Melanin and its precursors III. The influence of adrenochrome on the migration of bone marrow in vitro, compared with that of liver extract
Authors: Veer W. L. C. , Gaillard P. J. 
Published: September 2010

AbstractAdrenochrome has a promoting effect on the migration of bone marrow in vitro, in experiments as described by Overbeek, Gaillard and de Jongh to test and standardize liver extract on its anti‐anaemic properties. This promoting effect, however, is atypical in comparision with that of liver extract. (The commercial preparation Pernaemon was used).
Synthèse de Quelques Butadiènes Substitués
Authors: Backer H. J. , Blaas Th. A. H. 
Published: September 2010

AbstractCe mémoire décrit les propriétés de la sulfone du 2‐chloro‐3‐méthylbutadiène (A) et les produits (B), qu'on obtient en remplaçant le chlore par des groupes SR. Par chauffage, ces produits perdent de l'anhydride sulfureux et engendrent des butadiènes nouveaux:CH2:C(CH3).C(SR):CH2La sulfone du chloroprène a également un atome de chlore actif, et ses dérivés se prêtent de même à la préparation de butadiènes substitués: CH2:CH. CX:CH2.Les butadiènes sont peu stables. Si l'on veut les utiliser pour une “condensation diénique”, on pourrait les préparer sur le champ. Mais il est plus pratique de combiner la formation et la condensation, et de chauffer directement la sulfone avec le composé non‐saturé.
Dilatometric investigation of the phase transition in 1,2‐dibromoethane
Authors: Meerman P. G. 
Published: September 2010

AbstractThe phase transition in 1,2‐dibromoethane was studied dilatometrically. The transition was not accompanied by thermal hysteresis, but there were comparatively large superheating and supercooling effects. The transition temperature was found to be in excellent agreement with Pitzer's determination from heat content values.
The physical properties of glass II: The density of silicate glasses
Authors: Stevels J. M. 
Published: September 2010

AbstractA new formula is given according to which it is possible to calculate the volume V of a block of a glass containing one gram atom of O=ions. Over a very wide range V is independent of the number and the nature of the metallic ions present. The two constants occurring in the formula have a well defined physical meaning, which can be understood satisfactorily on the basis of the well‐known theory of the structure of glass by Zachariasen and Warren c.s. and its extensions by Dietzel. The limits of the validity of the formula are also discussed on the basis of Zachariasen's theory.Beside giving much new information concerning the structure of glasses in general, the formula can be transformed very easily into a simple density formula for glasses. This formula has been tested for 44 arbitrarily chosen glasses and it is found that the accuracy of the formula is the same as of the earlier purely empirical formulae of Winkelmann and Schott, English and Turner etc.
Quelques acides α‐sulfocarboxyliques non saturés simples
Authors: Backer H. J. , Mulder R. D. 
Published: September 2010

AbstractLe mémoire décrit les acides α‐sulfoacrylique, α‐sulfocrotonique, α‐sulfovinylacétique et α‐sulfo‐β,β‐diméthylacrylique.
Préparation D'Acides α,β‐Disulfocarboxyliques Simples
Authors: Backer H. J. , Mulder R. D. 
Published: September 2010

AbstractOn obtient les acides α,β‐disulfocarboxyliques en chauffant les sels des acides α‐sulfocarboxyliques non saturés (αβ) avec du sulfite acide. Leur structure est établie par le fait qu'on peut en isoler les composants optiquement actifs.