bluuebunny/crossref_metadata_2025_split huggingface dataset:
The bromination of naphthalene V. A theoretical treatment of the non‐catalytic mono‐bromination of gaseous naphthalene above 300°
Authors: Sixma F. L. J. , Wibaut J. P. 
Published: September 2010

AbstractIn the non‐catalytic bromination of gaseous naphthalene below 300° the main product is α‐monobromonaphthalene. Between 300° and 500° the ratio of β‐bromonaphthalene to α‐bromonaphthalene increases rapidly with the temperature. At still higher temperatures this ratio remains constant and is approximately equal to unity.It is assumed that the bromination of naphthalene proceeds as an electrophylic substitution at relatively low temperatures, whereas at high temperatures a radical substitution develops. A formula is derived which gives satisfactory agreement with the experimental values of the ratio of β‐ to α‐bromonaphthalene.
Etudes dans la Série du Thiophène. IV. ) Thiophénocarbazoles, thiophénobenzocarbazoles et leurs analogues isocycliques, et thiophénoacridines
Authors: Buu‐Hoï Ng. Ph. , Hoán Nguyên , Khôi Ng. H. 
Published: September 2010

AbstractDans ce travail, on décrit la synthèse et les propriétés d'une série de carbazoles polycycliques dérivant des benzocarbazoles et des dibenzocarbazoles par remplacement d'un des noyaux benzéniques par un noyau thiophéne (thiophénocarbazoles et thiophénobenzocarbazoles). Ces corps ont été préparés à partir d'arylhydrazines varieés d'une part, et d'autre part, du 2‐méthyl‐4‐céto‐4,5,6,7‐tétrahydrothionaphtène et du 2,7‐diméthyl‐3‐céto‐3,4,5,6‐tétrahydroiso‐thionaphtène. De nombreux composés analogues de la série isocyclique ont également été préparés à partir des mêmes arylhydrazines et de l'α‐tétralone, de son dérivé 7‐nitré, de la β‐tétralone, et de la 4‐méthylcyclohexanone. Au cours de ces recherches, on a apporté une contribution à la chimie des dérivés du thionaphtène et de l'isothionaphtène: en particulier, la synthèse du 2,4‐diméthylthionaphtène et du 2,6,7‐triméthyl‐3,4‐dihydroisothionaphtène a été réalisée. La plupart des carbazoles polycycliques décrits dans ce travail font l'objet d'études biologiques (pouvoir cancérigène éventuel). Le 2‐methyl‐4‐céto‐4,5,6,7‐tétrahydro‐thionaphtène et le 2,7‐diméthyl‐3‐céto‐3,4,5,6‐tétrahydroisothionaphtène donnent des réactions dePfitzinger‐Borscheavec l'isatine et son dérivé 5‐bromé, conduisant à des acides thiophéno‐dihydroacridine‐carboxyliques analogues au tétrophan.
Absorption spectrum and photodecomposition of o‐hydroxybenzenediazonium sulphate
Authors: de Jonge J. , Alink R. J. H. , Dijkstra R. 
Published: September 2010

AbstractThe long‐wave absorption maximum of o‐hydroxybenzenediazonium salts in water is found at 3950 Å, but in 50 % sulphuric acid as solvent it appears at 3500 Å.While the photodecomposition of o‐hydroxybenzenediazonium sulphate in water leads quantitatively to a derivative of cyclopentadiene, decomposition of the same compound in 50 % sulphuric acid results for the greater part in catechol.The effect of sulphuric acid, both on the spectrum and the photodecomposition, may be due to an increase in energy of the quinoid resonance structure of the o‐hydroxybenzenediazonium ion by the acid.
The solubility product of AgI and the complexes of AgI and iodide ions in water‐acetone mixtures
Authors: Mackor E. L. 
Published: September 2010

AbstractThe solubility product L of AgI in water‐acetone mixtures was determined from e.m.f. measurement in concentration elements. The diffusion potential was eliminated by Owen's method. As the solubility product was measured in three electrolyte concentrations the solubility product in infinite dilution could be found by extrapolation.The complex formation of AgI2− increases with increasing acetone concentration. The equilibrium constant K = \documentclass{article}\pagestyle{empty}\begin{document}${\rm K}=\frac{{{\rm a}_{{\rm I}^-}}}{{{\rm a}_{{\rm AgI}_{\rm 2}^-}}}$\end{document} was also determined by e.m.f. measurements. ‐RT ln K proves to be a linear function of the acetone concentration in mole %.The formation of higher complexes (AgnIn+m)m− is analysed. The complex Ag4I6= is the simplest complex that would confirm the experiment. A further proof has been found in the molecular weight determination in the ultracentrifuge.The standard free energy of solution of AgI, ‐RT ln L, is a nearly quadratic function of the acetone concentration in mole %. At low concentrations of acetone (up to 50 vol. %) the influence on L is low, but at higher concentrations the solubility decreases rapidly.The measurements were performed at 25.00 ± 0.02° C.
Structure and properties of compounds formed during the preparation of nickel‐on‐silica catalysts
Authors: van Eijk Van Voorthuijsen J. J. B. , Franzen P. 
Published: September 2010

AbstractSo far various metal hydrosilicates have been described in literature, but a detailed study of the components in the system metal oxide‐silica‐water occurring during the preparation of hydrogenation catalysts with added silica, has not been published. The results of a study of the system NiO‐SiO2‐H2O are given in this article, which also describes influence of the silica on the reducibility of the compounds.The formation of nickel hydrosilicates under various conditions was studied by means of X‐ray diffraction and thermal analysis. At relatively low temperatures (under 100° C) badly crystallized compounds are formed; thermal analysis indicated the presence of incomplete hydrosilicates, viz. nickel antigorite and/or nickel montmorillonite. The degree of crystallization of these hydrosilicate gels can be much improved by hydrothermal treatment.The stable end products resulting from this treatment are Ni(OH)2, Ni3(OH)4Si2O5 (nickel antigorite), Ni3(OH)2(Si2O5)2 (nickel montmorillonite) and SiO2 (quartz).The reducibility with hydrogen was measured as a function of the temperature. It varies greatly both with the silica content and with the degree of perfection of the hydrosilicate structure, the hydrothermally treated nickel montmorillonite being of all the most difficult to reduce. Generally the reduction leads to formation of nickel in a cubic form; however in the case of the hydrothermally treated nickel montmorillonite and nickel antigorite gels there are indications that part of the reduced nickel atoms remain in the places they occupied as ions in the hydrosilicate structure.
2‐Phenyl‐cyclopropane‐1‐carboxylic acids: Researches on plant growth regulators XX. Structure/activity V
Authors: Veldstra H. , van de Westeringh C. 
Published: September 2010

AbstractBy means of their action on the oleate coacervate and of the UV‐absorption spectra the 2‐phenyl‐cyclopropane‐carboxylic acids of m.p. 91° C and 105° C could be identified as the trans‐ and cis‐forms respectively.Of these acids, resembling very closely the trans‐ and cis‐cinnamic acids, the cis‐acid (m.p. 105° C) shows practically the same activity as cis‐cinnamic acid, whereas the trans‐acid, like trans‐cinnamic acid, is inactive.So here spatially equivalent structures are also comparable as to their physiological activity.
Les Limitations de la Reaction de Kishner—Wolff
Authors: Buu‐hoï Ng. Ph. , Hoán Ng. , Xuong Ng. D. 
Published: September 2010

AbstractDans ce travail, on a étudié sur plusieurs exemples de réduction d'aldéhydes et de cétones, certaines limitations de la réaction de Kishner‐Wolff. Il est montré que deux limitations importantes sont dûes, l'une à l'empêchement stérique, l'autre, à la grande mobilité des atomes d'halogènes sur certains composés hétérocycliques ou aromatiques. Une troisième limitation, moins importante, est dûe à la transposition des dérivés nitrés en dérivés aci‐nitrés.
Time‐dependence of boundary tensions of solutions. II. Experimental determination of the kinetics and equilibrium of adsorption at liquid‐liquid interfaces
Authors: Ward A. F. H. , Tordai L. 
Published: September 2010

AbstractBoundary tensions have been measured by the method of pendent drops for the interfaces between water and solutions of long‐chain fatty acids in hexane over a wide range of concentrations. At low concentrations the interfacial tensions were independent of the age of the surface. But above what appeared to be a critical concentration, characteristic of each fatty acid, the interfacial tensions decreased with time to final equilibrium values. For very low concentrations, below about 5 × 10−5 molal, the interfacial tension decreased linearly with concentration, the slope of the curve being identical for all the acids investigated (lauric, palmitic and stearic). In the concentration range where a time‐effect was observed, the fall in interfacial tension, and the time interval during which the fall occurred, both increased with increasing concentration. Experiments were carried out on the effect of varying temperature on the time‐effect. It was also shown that time‐effect occurred with an ester (ethyl palmitate).
Time‐Dependance of boundary tensions of solutions. III. Thermodynamics of the boundary‐bulk equilibrium of fatty acids in hexane‐water systems
Authors: Ward A. F. H. , Tordai L. 
Published: September 2010

AbstractThe activity of the solute in the adsorbed layer is calculated, and from this is obtained the activity in bulk by means of interfacial tension data at very low concentrations, using the method previously devised by the authors. This allows the investigation of the equilibrium between single and associated fatty acid molecules in hexane. It is shown that there is a simple equilibrium between monomers and dimers with lauric and palmitic acids, and the standard free energy of dimerisation is calculated, but the equilibrium with stearic acid is more complicated. The standard free energy of adsorption is calculated and it found to be independent of the chain‐length of the acid.
Vapour pressures and heats of vaporization of benzene
Authors: Gottschal A. J. , Korvezee A. E. 
Published: September 2010

AbstractStarting from two chosen experimental vapour pressure values of benzene, we have calculated:1°. the vapour pressure curve up to the boiling point;2°. the heats of vaporization along this curve.The necessary additional information concerns specific heats and specific volumes. The formulae have been taken from the preceding paper.The resulting vapour pressures are compared with the more recent Antoine equations. The heats of vaporization found along the same line prove to be in agreement with the calorimetric observations. Moreover, the calculations reveal with an appreciable precision the true form of the ΔH(T) relationship for benzene.
Researches on plant growth regulators XXII. Structure/activity VII: Sulphonic acids and related compounds
Authors: Veldstra H. , Kruyt W. , van der Steen E. J. , Åberg Böurje 
Published: September 2010

AbstractAt 10−4 ‐ 10−2 mol/l a number of sulphonic acids and related compounds, especially indole (3) methane‐sulphonic acid and 2,3,6‐trichlorophenylmethanesulphonic acid were found to be active as growth substances in the pea test, Avena straight growth test and flax root test. These acids being completely dissociated at physiological pH values, the anion must be the active form.The relatively low structural specificity of the polar group in the side chain of active compounds is considered to be indicative for a physicochemical type of action.
Esters thiolsulfiniques
Authors: Backer H. J. , Kloosterziel H. 
Published: September 2010

AbstractLes esters thiolsulfiniques se forment lorsqu'on fait réagir les chlorures arylsulfiniques sur les mercaptannes en présence de pyridine.Les thiolsulfinates liquides ou dissous ne sont pas stables. Leur décomposition spontanée effectue une “disproportionnation” en disulfure et thiolsulfonate.Pour les rayons ultraviolets tous les esters thiolsulfiniques présentent une absorption caractéristique qui change sous l'influence d'alcool.
Nitrating acids consisting of nitric acid and sulfur trioxide
Authors: Heertjes P. M. , Revallier L. J. 
Published: September 2010

AbstractSome physico‐chemical properties of the system HNO3‐SO3are described. From the melting point curve the existence of some crystalline compounds could be derived. The very stable compound HNO3. 2SO3was isolated (m.p. 112° C), a compound ‐ possibly 2HNO. 3SO3‐ was found (m.p. 106° C), and a compound HNO3. 3SO3could be isolated (m.p. 41° C).Liquid HNO3and SO3are not completely miscible. Between 90% SO3and nearly 100% SO3there exists a miscibility gap.The vapour pressure diagram of the system HNO3‐SO3was also determined. The minimum in this diagram corresponds to HNO3. 2SO3. The vapour of mixtures on the HNO3side of this minimum contains HNO3and N2O5. On the SO3side of the minimum of vapour contains SO3.It is posible to absorb most of SO3from contact gas in mixtures with 80‐82% of SO3at 25° C. In molten HNO3. 2SO3at 110° C the absorption of contact gas proceeds with a yield of over 90%.
Synthese und bacterizide Wirkung einiger quaternärer, höherer Alkyl‐ und Alkenyl‐bis‐(2‐oxyäthyl)‐Ammoniumsalze
Authors: Stefanović Gjorgje , Ćirić Jovan 
Published: September 2010

AbstractZur Prüfung der bactericiden Wirkung von quaternären Bis‐(2‐oxyäthyl)‐ammonium‐verbindungen mit höheren Kohlenwasserstoffresten wurden Decyl‐, Hexadecyl, Octadec‐9‐enyl, 11‐Cyclopent‐2′‐enyl‐n‐undecyl‐ und 13‐Cyclopent‐2′‐enyl‐n‐tridecyl‐bis‐(2″‐oxyäthyl)‐amine und die entsprechenden Amine, welche die den im Chaulmoograöl vorhandenen Fettsäuren entsprechenden Reste enthalten, hergestellt und mit Benzylchlorid umgesetzt.Diese quaternären Ammonium‐salze besitzen eine hohe bactericide Wirksamkeit. Sie töten innerhalb von 2.5 Minuten S. aureus und B. Gaertner in Verdünnungen von 1: 1000 bis 1: 10000 ab.
Imenes derived from methylsulphonyl‐acetonitrile: (Properties of the sulphonyl group XLIII)
Authors: Dijkstra R. , Backer H. J. 
Published: September 2010

AbstractWhen reacting diazomethane on nitriles of the type RSO2‐CHXCN, where X is a negative group, methylation on the nitrogen atom often occurs. In the case of bis‐methylsulphonyl‐acetonitrile, the N‐methyl derivative is formed exclusively: (CH3SO2)2CCNCH3. The less acidic methylsulphoxyl‐methylsulphonyl‐acetonitrile forms only the C‐methyl derivative: (CH3SO)(CH3SO2)C(CH3)CN.
Synthetic oxytocics. IV. 3‐(piperidyl‐(2)‐methyl‐) indoles and related compounds
Authors: Akkerman A. M. , Veldstra H. 
Published: September 2010

AbstractThe synthesis of a number of 3‐(piperidyl‐(2)‐methyl‐) indoles and of some related compounds is described, together with that of an additional number of 3‐(piperidyl‐(N)‐methyl‐) indoles (cf.). An analysis of the relationship between structure and oxytocic activity (data ofvan Proosdij‐Hartzemaandde Jongh) shows that several structural and spatial details, decisive for the activity of the ergot alkaloids, have no such influence with the synthetic compounds, though the importance of the general pattern of the alkaloids is discernable. So the 3‐(piperidyl‐(2)‐methyl‐) indoles are found to be less active and less specific than the 3‐(piperidyl‐(N)‐methyl‐)‐indoles.
The electrical conductivity of concentrated aqueous electrolytic solutions
Authors: Gellings P. J. 
Published: September 2010

AbstractA semi‐empirical equation for the conductivity of concentrated electrolytic solutions is derived from the Debye‐Hückel‐Onsager limiting law. The comparison of this equation with experiment shows agreement within a few per cent, or better, up to 4 to 5 N and in one case even up to 11 N.Measurements on NaNO3 up to 4.85 N and K5Fe(CN)6 up to 2.96 N are reported. Details of the null‐point detector and the variable‐frequency oscillator used in the bridge circuit are also given.
Investigations on sterols. VI The preparation of dihydrotachysterol2
Authors: Westerhof P. , Buisman J. A. Keverling 
Published: September 2010

AbstractThe preparation of dihydrotachysterol2 to be used as a standard in biological experiments was studied. The best yields were obtained by reduction of tachysterol2 with excess alkali metal, dissolved in liquid ammonia or suspended in a secondary amine. A laboratory method for the preparation of tachysterol2 is given.
Reduction potentials of various aromatic hydrocarbons and their univalent anions
Authors: Hoijtink G. J. , de Boer E. , van der Meij P. H. , Weijland W. P. 
Published: September 2010

AbstractPotentiometric titrations of solutions of various aromatic hydrocarbons in 1,2‐dimethoxyethane and tetrahydrofuran with a solution of biphenylsodium have shown chemical reduction to proceed in two stages:
equation image
The reduction potentials of the aromatic hydrocarbons, calculated from the potentiometric curve, are in good agreement with the half‐wave potentials obtained from polarographic reductions in 96% dioxan‐water. The standard potentials of the first reduction step expressed in Volts against the standard potential of biphenyl fit the following equation:

with γ = ‐ 2.19 ± 0.059 e.V. (2 × stand. dev. from mean) in which a stands for the root of the m.o. secular equation (overlap S = 0.25 included) corresponding to the lowest non‐occupied π‐orbital of the hydrocarbon and γ is the resonance‐parameter.The electrochemical series of aromatic hydrocarbons including a rough estimate of the standard potential of sodium in 1,2‐dimethoxyethane and the mechanism of chemical reduction in inert and proton‐active solvents are discussed.
Partition equilibria of indium halide complexes
Authors: Rossotti F. J. C. 
Published: September 2010

AbstractIn spite of many additional complications, the extraction of complexes with inorganic ligands may be treated in the same way as the extraction of complexes with organic ligands. A general method of deducing the formula of the extracted species from studies of partition equilibria is outlined. Application of this method to the partition of tracer concentrations of the indium halide complexes indicates that a number of different species may be extracted. Although the hydrated acido‐complex, HInX4, aq, is the predominant species extracted from halogen acid solutions, significant proportions of the trihalide and complexes or ion‐pairs such as NaInX4 partition from halide media at relatively low acidities. The relative extractability of indium into a number of organic solvents follows the same general order for solutions in hydrochloric, hydrobromic and hydriodic acids.
Die Struktur der Einschlussverbindungen des Wassers (Gashydrate) und des Phenols
Authors: von Stackelberg M. 
Published: September 2010

AbstractBezüglich der Gashydrate wird auf einige noch offene Probleme ihrer Struktur hingewiesen.Für die Einschlussverbindungen des Phenols wird die Kristallstruktur angegeben.
Application of paper chromatography to the identification of accelerators and antioxidants : I. Introduction; detection of guanidines and thioureas
Authors: Zijp J. W. H. 
Published: September 2010

AbstractIn this paper the various difficulties in the identification of accelerators and antioxidants in rubber compounds are reviewed. A detailed procedure for the detection of four guanidine derivatives by paper chromatography is mentioned. The identification of diphenyl thiourea and diorthotolyl thiourea is also described.
Application of paper chromatography to the identification of accelerators and antioxidants: III. Detection of dithiocarbamates and thiuram sulphides
Authors: Zijp J. W. H. 
Published: September 2010

AbstractIn this paper a detailed procedure is given for the paper‐chromatographic separation and identification of dithiocarbamates, which are used as ultraaccelerators in the rubber industry. These dithiocarbamates decompose in acid medium into secondary amines. The salts of these amines are better soluble in water than the dithiocarbamates, and are therefore more suitable for a paper‐chromatographic separation.A method for the simultaneous detection of dithiocarbamates and thiuram sulphides is also described.
Investigations on sterols XI : Preparation of 13α‐androstene derivatives
Authors: Bots J. P. L. 
Published: September 2010

AbstractBy irradiation of androst‐5‐en‐3β‐ol‐17‐one with U.V. light (λ>280mμ) 13α‐androst‐5‐en‐3β‐ol‐17‐one was obtained. This substance was converted into a mixture of the C17 epimers of 13α‐androst‐4‐en‐17‐ol‐3‐one, both of which were obtained in a pure state.
Über die Nitrierung des N‐Oxyds des 3‐Hydroxypyridins
Authors: Lewicka Krystyna , Plaźek Edwin 
Published: September 2010

AbstractDie Nitrierung des N‐Oxyds des 3‐Hydroxypyridins ist untersucht worden. Es wurde ein Mononitroderivat erhalten, welches sich als das N‐Oxyd des 2‐Nitro‐3‐hydroxypyridins erwies. Die Reduktion der Verbindung führte zum 2‐Amino‐3‐hydroxypyridin, die Reaktion mit PCl3und PBr3in Chloroform zur Bildung des 2‐Chlor‐3‐hydroxypyridins bzw. des 2‐Brom‐3‐oxypyridins.
Stereospecific synthesis and optical resolution of 5‐hydroxypipecolic acid
Authors: Beyerman H. C. , Boekee P. 
Published: September 2010

AbstractThe synthesis is described of 5‐hydroxypipecolic acid by reduction with sodium borohydride of the corresponding keto‐acid, which in turn was prepared from glutamic acid. This reduction proceeds without any appreciable formation ofallo‐isomer.The optical resolution is also described and the rotations of the optical antipodes are compared with those mentioned in the literature for the natural product.Further evidence is given for thecis‐OH/COOH configuration of theDL‐allo‐acid.
Square wave electrolysis IV. Results and discussion
Authors: Wijnen M. D. , Smit W. M. 
Published: September 2010

AbstractThe cyclic potential‐step method and the cyclic current‐step method are applied to two Red/Ox systems. Values of the standard exchange current density and of the transfer coefficient of both the ferro‐ferri system in 1M H2SO4 and the ferrocyanide‐ferricyanide system in 1M KCl are determined. The results obtained by the two methods are in good agreement with each other. A comparison is made with data obtained by other methods, mentioned in the literature.