bluuebunny/crossref_metadata_2025_split huggingface dataset:
Synthese von L‐ und D‐glutaminsäure‐1,2‐C14 13. Mitteilung über die Chemie der Tumoren
Authors: Kögl F. , Halberstadt J. , Barendregt T. J. 
Published: September 2010

AbstractAusgehend von radioaktivem Bariumcarbonat wurde über Natriumbicarbonat, Natriumformiat, Natriumoxalat und Silberoxalat radioaktiver Oxalsäuredimethylester gewonnen. Durch Kondensation mit Bernsteinsäuredimethylester und Spaltung mit Salzsäure entstand α‐Ketoglutarsäure, die durch reduktive Aminierung in DL‐Glutaminsäure‐1,2‐C14 umgesetzt wurde. Die Gewinnung der radioaktiven Antipoden erfolgte in der bei Glutaminsäure leicht durchführbaren Weise durch fraktionierte Kristallisation nach Zusatz des betreffenden „leichten”︁ AntipodenVgl. hierzu die Bemerkungen am Schluss der Arbeit
).Die zur Bestimmung der Radioaktivität angewandte Methodik wird kurz beschrieben.) Vgl. hierzu die Bemerkungen am Schluss der Arbeit.
Contribution to the knowledge of metanethole II
Authors: van der Zanden J. M. , de Vries G. 
Published: September 2010

AbstractSynthesis of 1‐p‐methoxyphenyl‐2‐methyl‐3‐ethyl‐6‐methoxy‐hydrindene:magnified imageof β‐ethyl‐p‐methoxycinnamic acid:magnified imageand of 2‐methyl‐3‐p‐methoxyphenyl‐5‐methoxyindenone:magnified image
General considerations concerning the number of virtual phases
Authors: Zernike J. 
Published: September 2010

AbstractA formula is deduced showing that ρ phases becoming critically identical should be counted as 2ρ‐1 virtual phases. Again no more than two phases having the same composition can be in equilibrium, whatever the number of components. Finally two phases having the same composition cannot be in equilibrium with a third phase with which one of these phases becomes critically identical. A few examples from the literature found to be at variance with these rules are discussed.
Einfluss Mittlerer Ionenkonzentrationen auf die Elektrostatische Energie von Fadenmolekülionen in Lösung
Authors: Künzle O. 
Published: September 2010

AbstractUsing polymethacrylic acid as example it is shown that the electric charges cause the chain molecules to become expanded. The expansion decreases when the concentration is increased or when salts are added. This contraction is ascribed to an increase of ionic strength.A general expression is developed for the electrical free energy of statistically coiled, electrically charged chain molecules. In this the end‐to‐end distancehof the polymer molecule is used as characteristic parameter for the shape.The distribution of ions with opposite charge and the variations of potential inside and outside of a coiled molecule are computed in accordance with the method ofDebijeandHückel.In special cases, i.e. various concentrations and different amounts of added salt, the electrical free energy is calculated as a function ofh(the distribution of the oppositely charged ions being taken into account).Using the free energy‐hfunction so found,h2and the specific viscosity are calculated and compared with experiments on polymethacrylic acid.
Polymérisation et copolymérisation du m‐nitrostyrène
Authors: Smets G. , Reckers A. 
Published: September 2010

AbstractLa polymérisation du méta‐nitrostyrène est caractérisé par une vitesse de polymérisation proportionelle à la concentration en intiateur utilisée; ce comportement s'interprête par un transfert de chaïne désactivant, dû à la présence d'un groupe nitré dans le noyau benzénique.De même que les polymères, les copolymères, obtenus au départ de m‐nitrostyrène et de styrène, méthacrylate de méthyle ou chlorostyrène, ont toujours un poids moléculaire très bas; la validité du schéma habituel de la copolymérisation dans ce cas particulier est discutée. Les valeurs apparentes de r1 et de r2 sont indiquées pour les différents systèmes de monomères étudiés.
The hydrolysis and polycondensation of tetra alkoxysilanes
Authors: Aelion R. , Loebel A. , Eirich F. 
Published: September 2010

AbstractA comparative study of the hydrolysis of the symmetrical orthosilicates, tetra‐ethyl,‐ tetra‐butyl, tetra‐hexyl, tetra‐2,6‐dimethyl‐heptyl‐4‐silicate, and of the unsymmetrical orthosilicates, diethyl‐dihexyl, diethyl‐di‐2‐methylpentyl‐4, diethyl‐diheptyl‐2, diethyl‐di‐2,6‐dimethyl‐heptyl‐4‐silicate, has been undertaken. A mechanism of the hydrolysis and of the polycondensation reaction of the silicols formed is proposed. Methods of preparation of some polyalkoxysiloxanes are described and the boiling points, melting points and densities determined. The higher polymers obtained by hydrolysis of alkoxy silicates are always highly cross‐linked siloxane networks. Attempts to obtain linear polyalkoxysiloxanes of high molecular weights by the hydrolysis of unsymmetrical esters have been found impracticable.
Velocity of hydrolysis of sodium chloroacetate in alkaline medium and concentrated solutions)
Authors: Nanninga L. B. 
Published: September 2010

AbstractThe reaction velocity of the hydrolysis of sodium monochloroacetate was determined in concentrated solutions and alkaline medium at 40° and 50°.It was found that the reaction follows the bimolecular equation. However, the reaction constant increases considerably with the normality of the hydroxide, which was explained by an effect of the total electrolyte concentration. The temperature coëfficient of the reaction was calculated to be 3.0 per 10°.
Kinetic analysis of organic halides. Part I. Analysis of low molecular monohalides
Authors: Salomon G. , Ultée A. J. 
Published: September 2010

AbstractA new kinetic test has been applied to the estimation of mixtures of two or more organic halides. The reactivity of a halide group with an organic base is a characteristic property of the group and can therefore be used for its identification.The rate of these halide‐base reactions increases with the strength of the base and the dielectric constant of the medium. The latter factor becomes preponderant in the dissociation of tertiary halides to olefins. The dependence of the rate of halogen ion formation on the concentration of the base is higher than second order.As the chain length and branching of the halide chain have little influence on the reaction rate, group reactivity decreases therefore in the usual series: allyl > primary > secondary > cyclohexyl >> vinyl.Tertiary halides are distinguished by their high rate of dissociation in pure aniline.A system of analysis has been drawn up and examples of application are given. The kinetic analysis of macromolecular halides (part II) is based on these model experiments.
Size, viscosity and precipitation of polymer molecules in solution
Authors: Kunst E. D. 
Published: September 2010

Les viscosités intrinsèques de fractions de polystyrène et de polyisobutylène ont été déterminées, ainsi que leurs poids et dimensions moléculaires par diffusion de la lumière.Les relations entre viscosité et dimensions d'une part et entre viscosité et poids moléculaire de l'autre, ont été analysées à l'aide des théories récentes de la viscosité des solutions macromoléculaires. L'accord avec la théorie est qualitatif et non quantitatif.D'autre part, on a étudié la relation entre les dimensions, le solvant et la température. Pour le polystyrène les dimensions sont uniquement fonction de la pente A2 de la courbe de (Hc/τ) en f(c), quelle que soit la température; on en conclue que la barrière de potentiel s'opposant à la rotation libre est très raide.Pour le polyisobutylène les dimensions augmentent avec la température pour une valeur constante de A2. Ici il y aurait donc deux barrières de potentiel, dont l'une empêche la réalisation des configurations très enroulées, et dont l'autre, moins raide, empêche la réalisation des configurations étendues. Finalement, l'adsorption préférentielle du solvant dans un mélange solvant—précipitant est discutée. Pour des raisons encore inconnues l'adsorption se présente si l'éthanol est le précipitant et non si l'hexane est est le précipitant.
Etude sur le Mécanisme de la Réaction Rubrénique: Le bis(p‐diméthylaminophényl)phényléthynylcarbinol, ses propriétés halochromiques: Un colorant vert à fonction acétylénique
Authors: Dufraisse M. Charles , Lefrancq Jean , Barbieri Pierre 
Published: September 2010

AbstractLe bis‐(p‐diméthylaminophényl)phényléthynylcarbinol, décrit dans le mémoire, se rapproche étroitement, par ses propriétés halochromiques, du bis (p‐diméthylaminophényl)phénylcarbinol, base du vert malachite, si ce n'est que la teinte des sels est plus profonde. Toutefois, à la différence du second, le premier s'isomérise en cétone éthylénique, ce qui bouleverse le caractére halochrome de la molécule. Les propriétés tinctoriales ont été examinées. L'impossibilité de passer par la méthode usuelle du carbinol, ou de ses sels colorés, au rubrène correspondant suggère l'idée que le premier temps de la réaction rubrénique ne doit pas être un décrochage d'ion négatif.
Remarks on a paper by Ishikawa and sakurai on the synthesis of α‐pentyl‐2‐hydroxycinnamaldehyde and α‐pentyl‐3‐methoxy‐4‐hydroxycinnamaldehyde
Authors: Verkade P. E. , Meerburg W. 
Published: September 2010

AbstractIt is shown that α‐pentyl‐2‐hydroxycinnamaldehyde and α‐pentyl‐3‐methoxy‐4‐hydroxycinnamaldehyde cannot be obtained in the way indicated by the above‐mentioned authors.
The structure of the thiosulphate ion in aqueous solution
Authors: Gerding H. , Eriks K. 
Published: September 2010

AbstractThe Raman frequencies of the S2O3″ ion in aqueous solution were redetermined and the depolarization ratios of the Raman lines of this ion are given here for the first time. The experimental material available makes it very probable that the S2O3″ion has the symmetry C3v. The force constants f(S.O), f(S.S), d(S.O) are calculated. Some remarks are made with regard to another structure proposed for S2O3″ and to some calculations of the theoretical frequency spectrum given in the literature.
The influence of SiO2 on the activity of nickel catalysts
Authors: van Eijk van Voorthuijsen J. J. B. , Franzen P. 
Published: September 2010

AbstractUnder appropriate conditions Ni(OH)2 and silica gel can form two compounds: Ni3(OH)4Si2O5 nickel antigorite and Ni3(OH)2(Si2O5)2 nickel montmorillonite. These two compounds, together with Ni(OH)2, are present in the pre‐reduction stage of Ni‐on‐SiO2 catalysts depending on the Ni/Si ratio. Their properties are a determining factor for the activity of the catalysts prepared from them by reduction.
The chloropyridines
Authors: den Hertog H. J. , Schogt J. C. M. , de Bruyn J. , de Klerk A. 
Published: September 2010

AbstractThe synthesis and some chemical properties are described of 2,4,5‐trichloropyridine, the only chloropyridine which has as yet not been mentioned in the literature.Six other chloropyridines, which have only been prepared once previously, have been examined more closely.It has been shown that a compound, which Königs, Mields and Gurlt obtained by heating 4‐nitraminopyridine with hydrochloric acid, is not 3,4‐dichloropyridine as stated by these investigators, but 4‐amino‐3,5‐dichloropyridine. 3,4‐Dichloropyridine has been prepared from 4‐hydroxypyridine via the well known 4‐chloro‐3‐nitropyridine.Further it appeared that a solid, m.p. 74°‐75°, which Sell and Dootson obtained by chlorination of pyridine and which they assumed to be 2,3,4,6‐tetrachloropyridine, must have been a mixture of chlorinated pyridines. We have synthesised 2,3,4,6‐tetrachloropyridine from 2,4‐dihydroxypyridine via 2,4‐dichloro‐3‐nitropyridine and from 4‐amino‐2,6‐dichloropyridine.The structure has been established of twenty five compounds discussed in connection with the chloropyridines mentioned above.Finally, the melting points and boiling points of the nineteen chloropyridines have been determined or verified.
Some derivatives of methacrylic acid
Authors: Heyboer J. , Staverman A. J. 
Published: September 2010

AbstractThe following substances, not yet described in the literature, were prepared:N‐tert‐butyl methacrylamide, m.p. 59° C, b.p. 111°° C/42 mm.tert‐butyl methacrylate, b.p. 136° C, fr.p. −48° C.N‐methacrylyl‐benzenesulphonamide, m.p. 128–129° C.N‐methacrylyl‐p‐toluenesulphonamide, m.p. 153–154° C.An improved method of preparation for methacrylic acid and methacrylyl chloride is described.Densities and refractions of several of these compounds are given.Some of these compounds have been polymerised and the solubility of the polymers in various solvents has been determined.
Investigations in the vitamin‐A series. I. A new synthesis of vitamin‐A acid and vitamin‐A: (Preliminary communication)
Authors: Huisman H. O. 
Published: September 2010

AbstractThe chemical and physical properties of β‐ionylidene acetaldehyde, the important key intermediate for the synthesis of vitamin‐A, are given.Starting from β‐ionylidene acetaldehyde a new synthesis of vitamin‐A acid and vitamin‐A is described.
Thermodynamic properties of mixtures of alkanes differing in chain length. I. Heats of mixing
Authors: van der Waals J. H. , Hermans J. J. 
Published: September 2010

AbstractThe construction is given of an isothermal twin calorimeter in which the small heat absorption on mixing two alkanes is compensated by electric heating. Results are given for the systems n‐hexane‐n‐hexadecane (20° C), n‐heptane‐n‐hexadecane (20°, 25° C), n‐octane‐n‐hexadecane (20°, 30°, 50° C), n‐decane‐n‐hexadecane (20°, 30°, 73° C), n‐decane‐n‐dotriacontane (73° C) and 2,2,4‐trimethyl pentane‐n‐hexadecane (25° C). A recent theory of Tompa s is compared with the observed dependence of the heat of mixing on the difference in chain lengths of the constituent molecules. The strong temperature dependence of the heat of mixing found is discussed in its relation to the entropy of mixing.
4‐Hydroxy‐6‐amino‐isophthalic acid, A byproduct in the synthesis of p‐aminosalicylic acid from m‐aminophenol)
Authors: Beyerman H. C. , Alberda G. 
Published: September 2010

AbstractCarboxylation of m‐aminophenol under carbon dioxide pressure may yield not only p‐aminosalicylic acid (PAS), but also a dicarboxylic acid as a by‐product. For this by‐product the structure of the unknown 4‐hydroxy‐6‐amino‐isophthalic acid is proved.The possibility of the occurrence of 4‐hydroxy‐6‐amino‐isophthalic acid in commercial PAS for clinical use and of resulting implications is stressed.Preliminary data concerning toxicity and tuberculostatic activity are given.
The preparation of some 3‐hydroxy‐4‐pyridones substituted on the nitrogen atom
Authors: Kleipool R. J. C. , Wibaut J. P. 
Published: September 2010

AbstractN‐Methyl‐3‐hydroxy‐4‐pyridone‐6‐carboxylic acid is produced by the action of methylamine on meconic acid and, by splitting off carbon dioxide, N‐methyl‐3‐hydroxy‐4‐pyridone is obtained. Similar reactions occur with ethylamine and isopropylamine.By the action of these amines on 3‐hydroxy‐y‐pyrone the corresponding N‐alkyl‐3‐hydroxy‐4‐pyridones are obtained. A pyridone carrying a substituent on the nitrogen atom is obtained by the action of aminoacetal on the above mentioned pyrone derivative. The reaction between glycine and meconic acid is described.
Biphenyl derivatives II. Basic 4‐Biphenyl compounds
Authors: Goldschmidt  , Modderman P. 
Published: September 2010

AbstractContinuing investigations described in a preceding paper 1) N‐alkylated biphenyl‐4 and 4‐cyclohexyl phenyl‐substituted amines have been prepared and tested for pharmacological activities. N‐derivatives of (biphenyl‐4)‐methylamine, β‐(biphenyl‐4)‐ethylamine, 4‐(2′‐methoxy biphenyl)‐ethyl‐amine, 4‐(cyclohexyl phenyl)‐methylamine and β‐4‐(cyclohexyl phenyl)‐ethylamine are described.
The dielectric constants of some hexanes, heptanes and octanes
Authors: de Vos F. C. 
Published: September 2010

AbstractAn apparatus is described for the determination of the dielectric constants of small amounts of liquid, with an accuracy of 1—2 units in the fourth decimal place.With this apparatus some pure hexanes, heptanes and octanes were studied at temperatures between 20° and 50° C.The results of the measurements are used for the computation of the polarisability of the molecules with the aid of Böttcher's method.
Stabilisation of montmorillonite sols by chemical treatment. Part I. Properties of sodium and calcium montmorillonite sols
Authors: van Olphen H. 
Published: September 2010

AbstractAccording to ultramicroscopical counting and relative viscosity data the micelles of Na and Ca montmorillonite sols are minute flat crystal plates with an average thickness corresponding to that of a packet of about five crystal lattice layers only with an average diameter‐thickness ratio of the order of a few hundred. This is corroborated by electronmicrographs and X‐ray studies.The average thickness of the micelles decreases with decreasing sol concentration, indicating a concentration‐dependent association‐dissociation equilibruim of the crystal lattice layers.Montmorillonite is a peculiar colloid in the sense that the platy micelles may be assumed to bear two basically different double layers, one on the surface of the lattice and a second at the broken lattice edges. The two double layer potentials may even have a different sign.
Monobromocyclohexadiene and dibromocyclohexadiene
Authors: Wibaut J. P. , Haak F. A. 
Published: September 2010

AbstractThe substitution of bromine in cyclohexadiene‐1,4 with N‐bromosuccinimide has been investigated more closely. Monobromocyclohexadiene was isolated in a slightly impure form as an almost colourless liquid; this substance decomposes violently on warming to 100°. The action of two molecules of N‐bromosuccinimide on 1 mol. of cyclohexadiene‐1,4, furnishes, amongst other things, dibromocyclohexadiene, which has been proved by isolation of bromobenzene from the decomposition products of this compound. Alongside substitution, a considerable amount of bromine addition took place to give dibromocyclohexene.
Steric effects on mesomerism. V.) steric effects on mesomerism in derivatives ofpara‐nitro‐acetanilide
Authors: Wepster B. M. , Verkade P. E. 
Published: September 2010

AbstractThis paper contains data on the (pseudo) catalytic deacylation of a number of derivatives ofpara‐nitro‐acetanilide in which steric effects on mesomerism are to be expected. The rate of deacylation found for each compound is discussed in some detail on the basis of current electronic theory.Special attention is paid to a valency deflection hypothesis relating to thesemi‐cyclic bonds of the benzene nucleus.Finally, a general remark is made on the magnitude of the steric effects on mesomerism, which we have found in derivatives ofortho‐ andpara‐nitro‐acetanilide (part IV of this series and this paper).
The antitubercular activity of azo dyes. II. Monazo dyes derived from diazotized sulfa drugs and bis (4‐aminophenyl)‐sulfone and bisazo dyes from tetrazotized bis (4‐aminophenyl)‐sulfone and sulfa drugs
Authors: Sah Peter P. T. , Oneto John F. 
Published: September 2010

AbstractWith the aim of obtaining azo dyes with high chemotherapeutic properties, two groups of azo dyes were prepared for studies, namely, (1) monazo dyes by the diazotization of sulfa drugs and related amines and then coupling with bis(4‐aminophenyl)‐sulfone, and (2) bisazo dyes by the tetrazotization of bis(4‐aminophenyl)‐sulfone and then coupling with sulfa drugs.Biological tests seemed to indicate that the monazo dyes are in general more active than the corresponding bisazo dyes, which in turn are more active than the bisazo dyes described previously and prepared from tetrazotized bis(4‐aminophenyl)‐sulfone and various common coupling components.In this paper, the relationship between chemical structure and biological properties (notable antitubercular in vitro) has been again discussed.
The decomposition of aliphatic azo‐compounds: II
Authors: Bickel A. F. , Waters W. A. 
Published: September 2010

AbstractThe thermal decomposition of 2,2′‐azo‐isobutyronitrile, which yields the radical (CH3)2Ċ‐CN, has been investigated with a view to establishing the nature of the termination process of the polymerization of methacrylonitrile.The results of these experiments may indicate that the chain termination in the above polymerization occurs mainly by combination and only to a small extent by disproportionation of the polymer radicals.
The electrokinetic behaviour of freshly prepared γ‐ and α‐FeOOH
Authors: van Schuylenborgh J. , Arens P. L. 
Published: September 2010

Abstractα‐FeOOH and γ‐FeOOH have been prepared in different ways and their electrokinetic behaviour was investigated.Dilution of the solution containing the components from which the minerals were synthesized led to a decrease of the isoelectric point (pH) of these substances. Drying of the moist preparations had the same effect.These results have been correlated with those from Röntgenographic and differential thermal analysis of the preparations.
Derivatives of oxazolidinedione‐2,4: I. Alkylation of the oxazolidinedione ring
Authors: Rekker R. F. , Verleur H. , Nauta W. Th. 
Published: September 2010

AbstractDepending on the method of working, alkylation of 5,5‐dimethyl‐oxazolidinedione‐2,4 leads to 3‐alkyl‐5,5‐dimethyl‐oxazolidinedione‐2,4 or an alkyl derivative of a lactim form of 5,5‐dimethyl‐oxazolidinedione‐2,4.It could be shown that the compound obtained by Spielman, by methylating 5,5‐dimethyl‐oxazolidinedione‐2,4 with dimethyl sulphate, had indeed the structure of 3,5,5,‐trimethyl‐oxazolidinedione‐2,4.Methylation of the silver salt of 5,5‐dimethyl‐oxazolidinedione‐2,4 with methyl iodide on the other hand, leads to the formation of an oxygen‐methylated compound.In connection with this matter, several syntheses, which might lead to the formation of 3,5,5‐trimethyl‐oxazolidinedione‐2,4 were submitted to a closer examination.
The synthesis of kawaïn
Authors: Kostermans D. G. F. R. 
Published: September 2010

AbstractKawaïn, one of the pyronones occurring in the kawa kawa‐plant (Piper methysticum), has been synthesised. The melting point of the synthetic substance is not identical with the melting point of kawaïn given by Borsche. Probably this is due to the fact, that Borsche did not obtain kawaïn in a pure state.
Aminolyse des 1,1,1‐trisulfones substituées: (Propriétés du groupe sulfonyle XV
Authors: Backer H. J. 
Published: September 2010

AbstractLes sulfones qui sont susceptibles de subir une hydrolyse se scindent généralement en acide sulfinique et composé hydroxylé (ou oléfinique). Soumises à l'action décomposante d'amines, ces sulfones peuvent engendrer également un acide sulfinique, le second produit étant une amine substituée.Par contre, les dérivés substitutées du tris‐méthylsulfonyl‐méthane ZC(SO2CH3)3 donnent, par hydrolyse, l'acide méthane‐sulfonique et des disulfones substituées.L'aminolyse de ces trisulfones a lieu dans la plupart des cas selon le même principe; d'acide méthanesulfonique se présente à l'état d'amide substitué.Cependant les thioaryl‐tris‐méthylsulfonyl‐méthanes font exception; tandis que l'hydrolyse alcaline suit le schéma des autres trisulfones, les amines attaquent le groupe thioaryle, au lieu d'un groupe méthylsulfonyle.Le mécanisme électronique des scissions observées est discuté.
Preparation of esters of gallic acid with higher primary alcohols
Authors: van der Kerk G. J. M. , Verbeek J. H. , Cleton J. C. F. 
Published: September 2010

AbstractThe esters of gallic acid and higher primary alcohols, especially fatty alcohols, have recently gained considerable interest as possible antioxidants for fats.Two independent methods for the preparation of these esters are described.In the first method the hitherto unknown compound galloyl chloride is converted into an ester of gallic acid by reaction with the appropriate alcohol.A new type of molecular addition compound between galloyl chloride and dioxane is described.The second method deals with the direct esterification of gallic acid with higher alcohols, which, until now, had not been successfully achieved.
The synthesis of 2‐mercapto‐4‐aminobenzoic acid
Authors: van Der Stelt C. , van Der Lugt W. , Nauta W. Th. 
Published: September 2010

AbstractThe synthesis of 2‐mercapto‐4‐aminobenzoic acid, a compound which is the sulphur analogue of p‐amino‐salicylic acid (2‐hydroxy‐4‐aminobenzoic acid), is described.