bluuebunny/crossref_metadata_2025_split huggingface dataset:
The use of chromatography paper in the study of sterol adduct formation
Authors: Meijer J. W. A. , Böttcher C. J. F. 
Published: September 2010

AbstractIn order to investigate the adduct‐forming properties of sterols with very small quantities of these compounds a method has been developed which uses acetylated chromatography paper as the medium in which the adduct can be formed.For the adduct formation of· cholesterol the results appear to be in agreement with those obtained on a larger scale by refluxing a solution of the sterol in the presence of the other component. The method is also suitable for the investigation of the adduct formation of sterols other than cholesterol.The relative humidity of the atmosphere in which the reaction takes place has an important influence on the adduct formation.Two colour reagents for detecting steroids on acetylated paper are described: a solution of benzenesulphonic acid in ether‐methanol, and a solution of antimony trichloride in tetrahydrofurane.
The reaction of phenol with formaldehyde. I. The separation and quantitative determination of low molecular reaction products by paper chromatography
Authors: Peer H. G. 
Published: September 2010

AbstractA comprehensive survey is given of the possibilities created for the analysis of phenol formaldehyde (PF) condensates by the development of paper chromatography, in particular through the application of benzeneacetic acid‐water as an eluent. A method for the quantitative determination of low molecular condensation products employing this eluent is given in detail.
Interpretation of the structure of polyhalogen complexes by the mo‐method
Authors: Havinga E. E. , Wiebenga E. H. 
Published: September 2010

AbstractThe structure of interhalogen compounds, polyhalide ions, and positive polyhalogen ions is discussed in terms of the LCAO‐MO method. The molecular orbitals were represented by a linear combination of the outerp‐orbitals of the halogen atoms. The Coulomb integrals were considered as a function of the electro‐negativity and the formal charge of the atoms.It is found that application of this method gives a consistent qualitative explanation of the bond angles, atomic configurations, and bond lengths in all polyhalogen complexes.
Methods for the analysis of lipids extracted from human arteries and other tissues
Authors: Böttcher C. J. F. , Woodford F. P. , Boelsma‐van Houte E. , van Gent C. M. 
Published: September 2010

AbstractAn investigation of methods for the extraction and analysis of lipids from human arteries is described. The analytical procedure developed has been tested for completeness of separation and absence of artefact formation. It can be applied to lipid mixtures amounting to as little as 50 mg or in some cases even less. The lipids can be separated into phospholipids, free fatty acids, sterol esters, and glycerides plus free sterols, and the fatty acid mixtures from these fractions analysed by gas chromatography after methylation. Examples of such analyses are given.
On the synthesis of derivatives of N‐(4‐pyridonyl)‐oxyacetic acid
Authors: Bojarska‐Dahlig H. N. 
Published: September 2010

AbstractN‐(3,5‐diiodo‐4‐pyridonyl)‐oxyacetic acid was synthesized by reacting 4‐hydroxy‐3,5‐diiodopyridine‐N‐oxide with chloroacetic acid in neutral medium, the yield amounting to 85 %.4‐Hydroxy‐3,5‐diiodo‐2‐methylpyridine‐N‐oxide was converted analogously, but in a lower yield, into the corresponding oxyacetic acid, but the 2,6‐dimethyl derivative of 4‐hydroxy‐3,5‐diiodopyridine‐N‐oxide did not react with chloroacetic acid.The synthesis and properties of several starting substances and intermediates, which are not yet recorded in the literature, are described.
The isothermal compressibilities of pure non‐polar liquids
Authors: Steinhardt Ralph G. 
Published: September 2010

AbstractA simple semi‐theoretical treatment shows that the relation χTγ3/2 = k between isothermal compressibility (χT) and surface tension (γ) implies that the isothermal compressibility of a non‐polar liquid is determined by its structure and average intermolecular distance, and by the electron polarizability of the molecules of which the liquid is composed. The temperature‐dependency of isothermal compressibility of non‐polar liquids composed of quasi‐spherical molecules may be attributed solely to the corresponding temperature‐dependency of the average intermolecular distance in such liquids.
Electron‐donor properties of the pyridine 1‐oxide ring
Authors: Katritzky A. R. 
Published: September 2010

AbstractAvailable evidence for the electron‐donor properties of the pyridine and pyridine 1‐oxide rings is briefly reviewed. The positions and intensities of the CN stretching band in cyano‐pyridines and ‐pyridine 1‐oxides confirms that electron availability in the pyridine ring decreases at the nuclear positions in the order 3≫4>2 and in the pyridine 1‐oxide ring in the order 4 ≫ 3 ∼ 2.
Ester interchange equilibria from dimethyl terephthalate and ethylene glycol
Authors: Challa G. 
Published: September 2010

AbstractEster interchange equilibrium products prepared from dimethyl terephthalate and ethylene glycol, in the presence of zinc acetate as a catalyst, have been investigated at 180 and 195°. For the analysis of these products quantitative volumetric methods for the determination of free methanol and of free ethylene glycol have been developed. In addition, a method for the fractional vacuum distillation and sublimation of methanol, ethylene glycol, dimethyl terephthalate, and β‐hydroxyethyl methyl terephthalate has been worked out.The analytical results are evaluated in terms of equilibrium constants for the various reversible reactions pertaining to the present system. All equilibrium constants are found to depend only slightly on temperature and composition. The small values of the equilibrium constants related to the removal of methyl ester groups are in line with the practical difficulty of achieving complete glycolysis of dimethyl terephthalate before polycondensation to polyethylene terephthalate starts.The most important result is the fact that the “molecular” equilibrium constant KI of the first step of the glycolysis of dimethyl terephthalate equals the corresponding overall equilibrium constant Ke in terms of functional groups after correction for the functionality of reactants and products. Prom this fact it is concluded that the “molecular” equilibrium constants KI and KII for the first and second step of the glycolysis are equal.
Square wave electrolysis III. Apparatus for the cyclic potential‐step and cyclic current‐step methods
Authors: Wijnen M. D. , Smit W. M. 
Published: September 2010

AbstractThe experimental setups required for the cyclic potential‐step and cyclic current‐step methods are thoroughly discussed. Attention is paid to the following subjects: conditions for linear diffusion, reference electrode, potentiostatic conditions, time‐symmetry of the applied square wave and deviations from coulomb‐symmetry.
The condensation of rhodanine and derivatives with benzaldehyde sulphonic acids
Authors: Allan F. J. , Allan G. G. , Crank G. , Jack J. 
Published: September 2010

AbstractThe condensation products of rhodanine and some of its derivatives with benzaldehyde sulphonic acids have been prepared with a view to obtaining compounds of increased fungicidal properties. The products differ from the majority of previously prepared rhodanine‐aldehyde condensation products in that they are appreciably soluble in water. From a fungitoxicological standpoint this increased solubility may well increase the activity of such fungicides as their availability in aqueous media is greatly increased. The condensation products formed relatively insoluble and often crystalline salts with many metallic ions. The precipitation of these salts was briefly considered from the analytical point of view. The condensations between the rhodanines and the benzaldehyde sulphonic acids were carried out in acid media and crystalline coloured products were obtained in good yield.
Investigations on pyrazine derivatives. VI. The reduction of 2,3,5,6‐tetraethoxycarbonylpyrazine with alkaline sodium dithionite
Authors: Mager H. I. X. , Berends W. 
Published: September 2010

AbstractA new convenient method is given for the preparation of 2,3,5,6‐tetraethoxycarbonyl‐1,4‐dihydropyrazine.
The infrared spectra of benzenoid and heteroaromatic nitro‐compounds
Authors: Katritzky A. R. , Simmons P. 
Published: September 2010

AbstractThe frequencies and apparent extinction coefficients for bands in the 1550, 1350, 1300, and 850 cm−1 regions for 11 ortho, 18 meta, and 29 para nitro‐benzenes and for 7 heteroaromatic nitro‐compounds are recorded.
Studies on vitamin D and related compounds XI investigations on sterols XIII the photoisomerisation of ergosterol
Authors: Rappoldt M. P. , Havinga E. 
Published: September 2010

AbstractKinetic experiments on the photoisomerisation of ergosterol were carried out using different sources of light. New methods of analysis for pre‐ergocalciferol and tachysterol2 had to be developed. The quantum yield of the photoisomerisation of ergosterol with ultraviolet light of 2537 Å was found to be 0.31 at 20°. This value was obtained when ether, ethanol and petroleum ether were used as solvents. Tachysterol2 is not formed from ergosterol during irradiation, but originates exclusively from pre‐ergocalciferol. Excited ergosterol falls back to its ground state (69%) or transforms to pre‐ergocalciferol (26%) and to unidentified products (5%).
L'Analyse par les Radioéléments de L'Aluminium de Très Haute Pureté Obtenu par la Technique de la Zone Fondue
Authors: Chaudron G. 
Published: September 2010

AbstractL'auteur met en évidence le grand intérêt de la technique des radioéléments lorsqu'il s'agit d'identifier des traces d'impuretés dans un métal très pur. La méthode s'applique particulièrement à l'aluminium purifié par la technique de la zone fondue. Les analyses permettent actuellement de doser plus de 40 éléments, parmi lesquels les terres rares.
Essai de la Détermination, par Spectrographie Infrarouge, de la Structure de L'Anhydride Iodique I2O5
Authors: Duval Clement , Lecomte Jean 
Published: September 2010

AbstractJusqu'à présent, on possède relativement peu de renseignements sur les positions des bandes infrarouges qui mettent en jeu des liaisons entre l'iode et l'oxygène. Dans la littérature, on trouve les fréquences propres des iodates métalliques de l'ion periodique, et de l'acide iodique, déterminées par le spectre de diffusion et, au moins partiellement, par le spectre d'absorption. Ces données nous serviront à interpréter le spectre d'absorption de l'anhydride iodique, que nous avons obtenu pour la première fois, à notre connaissance.
Studien über analytisch verwertbare Umsetzungen von Dämpfen niedrig siedender organischer Lösungsmittel in der Tüpfelanalyse
Authors: Feigl F. , Goldstein D. , Haguenauer‐Castro D. 
Published: September 2010

AbstractEs wurden in der Arbeitsweise der Tüpfelanalyse Versuche über den Eintritt von Dämpfen einiger niedrig siedender Lösungsmittel in Pyrolysenreaktionen angestellt. Es wurde gefunden:Pyrolytische Oxydationen unter Bildung von Halogen erfolgen bei Erhitzung von halogenhaltigen Lösungsmitteln mit höheren Metalloxyden auf 240°. Bei Erhitzung mit Kupferoxyd, Wolframsäure oder Chromsäure unterscheiden sich die Dämpfe von Chloroform und Tetrachlorkohlenstoff in charakteristischer Weise.Pyrolytische Reduktionen unter Bildung von Chlorwasserstoff erfolgen bei Erhitzung von Chloroform oder Tetrachlorkohlenstoff mit Benzoin auf 220°.Pyrolytische Hydrolysen unter Bildung von Halogenwasserstoff erfolgen bei Erhitzung von Tetrachlorkohlenstoff oder Chloroform mit Mangansulfatmonohydrat auf 240°. Bei Schwefelkohlenstoff erfolgt bei 270‐280° eine Pyrohydrolyse unter Bildung von Schwefelwasserstoff.Pyrolytische Ammonolyse unter Bildung von Cyanwasserstoff erfolgt bei Erhitzung von Chloroform mit Guanidinkarbonat auf 190°.Pyrolytische Disproportionierung unter Bildung von Chlor und Chlorwasserstoff erfolgt bei Erhitzung von Dämpfen halogenhaltiger Lösungsmittel mit katalytisch wirksamen Oxyden, Kieselsäure, Chromaten, Sulfaten und Kohlenstoff auf 250°.Über das Ausmass der pyrolytischen Reaktionen, denen plausible Umsetzungsgleichungen zugrundegelegt werden, können noch keine Aussagen gemacht werden. Sie sind indessen so weitgehend, um eine Reihe analytischer Anwendungen zu ermöglichen. Von diesen ist besonders die Unterscheidung von Tetrachlorkohlenstoff und Chloroform, deren Siedepunkte nahe beieinander liegen, von Interesse.
The determination of tungsten in high alloy steels by isotope dilution
Authors: Leliaert G. , Hoste J. , Eeckhaut Z. 
Published: September 2010

AbstractAn isotope dilution procedure using 185W has been developed for the determination of tungsten in high alloy steels. Tungsten is determined spectrophotometrically with hydroquinone in sulphuric acid medium, after homogeneous precipitation from a nitric acid‐hydrogen peroxide solution.For molybdenum‐vanadium‐tungsten alloy steels no further chemical separations are required. The radiometric correction is applied to the residual tungsten so as to minimize counting errors. Analyses carried out on N.B.S. samples showed good accuracy and precision.For high alloy steels containing niobium, tantalum and titanium a chemical separation of tungsten is necessary to avoid interference in the subsequent spectrophotometric determination. Although the recovery of tungsten is quite low, the magnesia method is entirely satisfactory.The method was succesfully tested on a number N.B.S. high alloy steels to which varying amounts of tantalum and titanum were added.
Recovery of nickel and cobalt from lateritic iron ores
Authors: Heertjes P. M. , van Nes C. L. 
Published: September 2010

AbstractIt was desired to increase the ratio of the amounts of nickel and cobalt with respect to iron, as found in lateritic iron ores and to recover almost all the nickel and cobalt in these ores.This was realised by converting nickel oxide and cobalt oxide almost selectively and completely into the corresponding chlorides. A stepwise process was used in which a gaseous mixture of steam and hydrogen chloride was passed through a fluidised bed of the granulated ore under proper conditions of temperature and concentration. The chlorides were recovered by extracting the chloridised ore with hot water.
A method for the determination of amyloid in plant seeds
Authors: Kooiman P. 
Published: September 2010

Abstract1) A colorimetric method has been elaborated for the determination of amyloids in plant seeds, based on the blue colour of the iodine complex in concentrated sodium sulphate solution.2) Details of the method are given and its possibilities and limitations are outlined.3) Three procedures for removing interfering starch are recommended.
The hydrogen‐deuterium exchange reaction of the t‐butyl group substituted in aromatic hydrocarbons
Authors: Dallinga G. , ter Maten G. 
Published: September 2010

AbstractA new type of hydrogen‐deuterium exchange reaction in acid media, viz. the exchange of hydrogen atoms of the t‐butyl group, substituted in benzene rings, has been found. The reaction is first‐order in the concentration of the hydrocarbon. There is no simple relation between the rate constant, k, and either the acidity function H0, or the concentration, ca, of the acid. Log k is, however, linearly related with (‐ H0 + log ca). The activation energy is 20.2 ± 0.3 kcal/mole.The results indicate that the exchange reaction of the t‐butyl group proceeds via an ionic intermediate in which the carbon‐carbon bond between the t‐butyl group and the aromatic ring is probably weakened. The rate‐determining step of the reaction is the formation of this intermediate.The exchange reaction seems to be closely related to isomerization and transalkylation reactions; the formation of the ionic intermediate may be a common step for all three reactions.
Latent heat of vaporisation and composition
Authors: Wright Franklin J. 
Published: September 2010

AbstractThe variation of vapor pressure and density with temperature up to the normal boiling point has been obtained for 32 homopolar liquids. From these measurements, the latent heats at the boiling point and the normal and true lyoparachors have been calculated. In keeping with Bowden and Jones's findings, the lyoparachors were found to be additive properties determined by the composition and molecular constitution of the compound. New bond and atom constants for the lyoparachors have been obtained.
Investigations on pesticidal phosphorus compounds II. On the structure of phosphorus compounds derived from 3‐amino‐1,2,4‐triazole
Authors: van den Bos B. G. 
Published: September 2010

AbstractIt is shown that in the compounds formed by reaction of 3‐amino‐1,2,4‐triazole or a 5‐substituted derivative thereof with a phosphoryl chloride the phosphoryl group is attached to the triazole ring.
Infra‐red absorption spectra of alkylthio compounds
Authors: Boonstra H. J. , Rinzema L. C. 
Published: September 2010

AbstractA survey is given of the characteristic frequencies of a number of alkylthio groups. The infra‐red absorption spectra of a few groups of unsaturated thioethers are discussed in detail, attention being drawn, among other things, to their resemblance to infra‐red absorption spectra of analogous chlorine compounds.
Preparation of some 4‐dimethylamino‐azobenzene derivatives with substituents in the 3‐ or in the 3‐ and the 5‐position
Authors: van Loon A. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractThe preparation of a number of dimethylamino‐azobenzene derivatives of the types I‐IV (see formulae below) is described. The choice of the methods of preparation depends on considerations about steric effects on mesomerism.
Physical properties of organic thiones: Part III. The evaluation of transition energies, resonance energies and charge diagrams of organic thiones and dithioates
Authors: Janssen M. J. 
Published: September 2010

AbstractAn empirical LCAO MO method, in which self‐consistency was introduced, was applied to molecules of the general structure ABCS and ACS2−, in which A and B are saturated radicals bonded to the thione or dithioate group by carbon, sulphur, oxygen or nitrogen.The transition energies for n → π* and π →π* transitions, the resonance energies and the charge diagrams are evaluated. The calculated transition energies proved to be related to the measured absorption frequencies for both transitions. A discrepancy is encountered between the experimental and theoretical assignment of the π → π* transition for the nitrogen‐containing thiones.
Phosphatidic acids and derivatives: XI. Infra‐red spectra of glycerol‐α‐kephalins and glycolkephalins
Authors: van Veen A. , Verkade P. E. 
Published: September 2010

AbstractIn the present paper we are publishing the infra‐red spectra of glycerol‐α‐kephalins and glycolkephalins synthesized in our laboratory. These spectra are discussed in relation with spectra of glycerol‐α‐kephalins already available in the literature.
Spectrophotometric investigations of the mechanism of complex formation: Part II. Complex formation of β‐phenylethyl bromide with aluminium bromide
Authors: Adema E. H. , Arnoldy H. , Visser R. , Sixma F. L. J. 
Published: September 2010

AbstractSpectrophotometric titration curves of β‐phenylethyl bromide and aluminium bromide at −80° in carbon disulphide and heptane at 430 and 250 mμ respectively show the formation of a 1 : 1 complex by a fast reaction, which goes to completion.
The Fries rearrangement of p‐tolyl and o‐tolyl acetate catalysed by aluminium chloride
Authors: Cullinane N. M. , Edwards B. F. R. , Bailey‐Wood V. V. 
Published: September 2010

AbstractThe rearrangement of p‐tolyl acetate in nitrobenzene solution catalysed by aluminium chloride gives the o‐hydroxyketone only as rearrangement product. o‐Tolyl acetate under the same treatment yields mainly the para‐substituted hydroxyketone together with a small amount only of the ortho‐substituted compound. Both of these rearrangements appear to be intramolecular and the interpretation proposed for the titanium tetrachloride catalysed transformations of these esters may also be applied in the present case.
Study of the reactions between titanium tetrachloride and ethylaluminium compounds in hydrocarbon solution: II. Gaseous reaction products
Authors: Arlman E. J. , de Jong J. R. 
Published: September 2010

AbstractGaseous reaction products from the systems AlEt3/TiCl4, AlEt2Cl/TiCl4 and AlEtCl2/TiCl4 in isooctane solution at 80°C have been studied. A set of reactions explaining the formation of the observed products H2, C2H6, C2H5Cl, n‐C4H10 and n‐C6H14 is given. It is possible to account nearly quantitatively for the conversion of the ethyl groups and for the extent of reduction of TiCl4.It appeared that the formation of ethane is partly due to dis‐proportionation of ethyl groups, and partly to ethyl groups abstracting hydrogen from the isooctane. In the system AlMe3/TiCl4 the methyl groups quantitatively react in the latter way to form CH4. The isooctane to a small extent decomposes into isobutane and isobutene or into isopentane and propene. It is supposed that the brown precipitates formed in the reduction of TiCl4 act as catalysts for this decomposition.
Investigations on sterols XIX: 6‐Dehydro‐9β, 10α‐progesterone from pregnenolone
Authors: Rappoldt M. P. , Westerhof P. 
Published: September 2010

AbstractPregna‐5, 7‐dien‐3β‐ol‐20‐one was irradiated with ultraviolet light to obtain the corresponding 9β, 10α compound. Oppenauer oxidation, followed by isomerization of 9β, 10α‐pregna‐5, 7‐dien‐3α‐ol‐20‐one, yielded 6‐dehydro‐9α, 10α‐progesterone.
U.V. spectra of derivatives of 1,3,5‐triazine
Authors: Koopman H. 
Published: September 2010

AbstractThe synthesis of four 2,4‐dichloro‐6‐(p substituted phenyl) 1,3,5‐triazines is described. The U.V. spectra of these compounds and those of the derivatives mentioned in the preceding papers 1,2,3 are dealt with and discussed.
Investigations in the vitamin B6‐series: II. Synthesis of 4,5‐dihydroxymethyl‐6‐hydroxy‐2‐methylpyridine, an isomer of vitamin B6
Authors: van der Wal B. , de Boer Th. J. , Huisman H. O. 
Published: September 2010

AbstractThe synthesis of 4,5‐dihydroxymethyl‐6‐hydroxy‐2‐methylpyridine, an isomer of vitamin B6, is described.This isomer is biologically inactive on the growth of Saccharomyces carlsbergensis.
Investigations in the vitamin B6−series: III. Reductions of an intermediate of the vitamin b6 synthesis with lithium aluminium hydride
Authors: van der Wal B. , de Boer Th. J. , Huisman H. O. 
Published: September 2010

AbstractAttempts are described to simplify the synthesis of vitamin B6 by a simultaneous reduction of the ester groups and reductive elimination of the chlorine atom in dimethyl 3‐amino‐6‐chloro‐2‐methylpyridine‐4,5‐dicarboxylate (III) with lithium aluminium hydride. After prolonged refluxing with a large excess of the reagent the chlorine free compound 3‐amino‐4,5‐dihydroxymethyl‐2‐methylpyridine (IV) could be isolated in low yield.
Ultraviolet absorption spectra of 1‐furfural and of 5‐hydroxymethyl‐furfural in aqueous buffers
Authors: Psarras Theodore , Tefteller J. Wilburn , Zimmerman Howard K. 
Published: September 2010

AbstractThe extinction coefficients in buffered aqueous solutions for furfural and for 5‐hydroxymethyl‐furfural (HMF) at their ultraviolet absorption maxima are respectively 16 800 ± 420 at 277 mμ for furfural and 17 900 ± 250 at 284 mμ for HMF. For both compounds, both the extinction and the maximum wavelength are unaffected by changes in pH over the range 3–10, in buffer capacity, or by a change from a phosphate‐citrate to a borate buffer. The extinction does diminish somewhat as the solution ages for each substance. This fact emphasizes the importance of determining the spectrum as soon as possible after the solution is prepared.