bluuebunny/crossref_metadata_2025_split huggingface dataset:
The estimation of small quantities of glycyrrhetinic acid in urine
Authors: van Katwijk V. M. , Huis L. G. 
Published: September 2010

AbstractA method is described by which 20 mg of glycyrrhetinic acid/24 hours urine can be quantitatively estimated. This method is based on the fact that a solution of glycyrrhetinic acid in 96% ethanol gives a maximum absorption in the U.V. region at 248 mμ. By means of a chromatographic method, using floridine earth as adsorbing agent, it is possible to obtain the glycyrrhetinic acid sufficiently pure for the determination of the UV absorption spectrum.With this method we investigated the urine of three patients who had been treated with this compound. No glycyrrhetinic acid could be demonstrated in these urines *).
The oxidation of phenols with copper‐amine catalysts and its relation to the mode of action of tyrosinase IV. Relations between hydrogen peroxide and the catalytic oxidation of phenols
Authors: Brackman W. , Havinga E. 
Published: September 2010

AbstractIn a previous paper a purely descriptive report was given on the kinetics of the catalytic oxidation of phenols with oxygen under the influence of copper‐morpholine complexes. Before discussing the mechanism of these reactions we thought it worth while to draw special attention to the ways in which H2O2 (a possible intermediate) may originate from and react with the catalytic systems under consideration.
Some thermodynamic properties of the system benzene ‐ 1,2‐dichloroethane. Part I: The heats of mixing
Authors: Ruiter L. H. 
Published: September 2010

AbstractThe heats of mixing of the system benzene ‐ 1,2 dichloroethane have been measured at three different temperatures (7.60°C, 25.00°C and 41.85°C) in a calorimeter of conventional design, using large quantities of liquid (350 ml). The apparatus and experimental procedure are described in detail. In the calculation of the heat exchange of the calorimeter with the surroundings, the method described by Coops et al 1) has been used. An elaborated heat‐of‐mixing experiment shows the application of this method to our calorimetric system.The results of each series of experiments have been represented by an equation of the form:ΔH/x (1−x) = a + b (2x−1) + c (2x−1)2 J/mole. The heats of mixing are positive, small and highly temperature‐dependent. They decrease with rising temperature.
The infrared spectrum of perchloromethyl mercaptan (trichloromethane sulphenyl chloride) CCl3SCl: Fermi‐splitting and isotope effect in the spectrum of carbon tetrachloride
Authors: Ketelaar J. A. A. , Vedder W. 
Published: September 2010

AbstractThe infrared spectrum of liquid CSCl4 has been measured from 3‐25μ. The experimental results are discussed and a complete analysis of the spectrum is given.Although some corrections in his vibrational assignment had to be made, the spectrum supports the structure proposed by Duchesne1), i.e. CCl4 with a chlorine atom replaced by sulphur and a chlorine atom attached to the sulphur at an angle to the CS bond.One of the fundamental frequencies shows Fermi‐splitting with a combination frequency. The difference between vapour and liquid state spectrum is used to prove the interpretation given. For comparison the shape of the Fermi‐doublet observed in the infrared spectrum of carbon tetrachloride is studied in the vapour and the liquid phase.
Potentiometric estimation of vanadium. II. Oxidation of Quadrivalent vanadium with KMnO4 in alkaline media
Authors: Issa I. M. , Daess A. M. 
Published: September 2010

AbstractQuadrivalent vanadium occurring in alkaline solutions as alkali vanadite can be readily oxidized by permanganate. The latter is reduced either to manganate in the presence of Ba+2 ions or to MnO2. These reactions proceed almost quantitatively under certain conditions. A method for the estimation of vanadium is developed, based upon the oxidation of V+4 to V+5 with excess KMnO4 in alkaline medium, followed by titrating the excess of oxidant with formic acid or monovalent thallium. The method is applicable to quantities of V+4 as low as 604 γ.
Reactions of ethyl bromide and aluminium bromide. II. Isomerisation of ethyl‐[1‐14C] bromide
Authors: Sixma F. L. J. , Hendriks H. 
Published: September 2010

AbstractThe isomerisation of ethyl‐[1‐14C] bromide to ethyl‐[2‐14C] bromide in the liquid phase is catalysed by aluminium bromide. From measurements of the reaction rate at temperatures between +25° and +50° the activation energy of this reaction appears to be 19.1 kcal/mole (± 2%).
The absolute heat of combustion of benzoic acid
Authors: Coops J. , Adriaanse N. , van Nes K. 
Published: September 2010

AbstractThe heats of combustion of some samples of pure benzoic acid, partly supplied by the National Bureau of Standards (Washington) and partly prepared by the authors, have been carefully measured by reference to electrical standards.The mean value of the absolute heat of combustion of benzoic acid under standard bomb conditions in some series of determinations carried out in the years 1946‐1948 is26438 ± 4 j/g.New determinations in 1954 showed a mean value of26435 ± 4 j/g.
Plant growth activity and chemical structure
Authors: Schoot C. J. , Klaassens K. H. 
Published: September 2010

AbstractA hypothesis relating to chemical structure and plant growth activity is formulated. The views of Hansch and Muir, Smith and Wain and Leaper and Bishop are correlated using as a basis the reaction between Ag3PO4 and phenoxyacetyl chlorides described in a previous article. The aryloxyacetic acids, the arylacetic acids and the arylcarboxylic acids are classified in the same scheme. Some indication is given as to the influence of the substituents in the phenoxyacetic acids. The rule of Leaper and Bishop is generalized.
Synthesis of 1,3,5‐tri‐tert. Butylbenzene
Authors: van Hartingsveldt W. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractA synthesis is described of 1,3,5‐tri‐tert.butylbenzene starting from 3,5‐di‐tert.butyltoluene.
Complex coacervation. II. Thermodynamic calculations on a specific model, with application to two component systems
Authors: Voorn M. J. 
Published: September 2010

AbstractIn part II A, a general expression is given for the calculation of the free energy of a solution containing 2 or more interacting poly‐electrolytes in a salt solution.From this expression, the conditions for thermodynamic equilibrium in 2 phase, j‐component systems are derived.In part II B these conditions are applied to a two component system consisting of a colloid‐colloid “salt” PQ in H2O, in the absence of simple salt KA.
The phase behaviour of n‐alkanes
Authors: Schaerer A. A. , Baylé G. G. , Mazee W. M. 
Published: September 2010

AbstractIn the homologous series of n‐alkanes two alternating effects are known, viz. the familiar alternation of melting points for the short‐chain members and the recently reported alternation of transition points for members with chains of more than 20 carbon atoms.A further study of the phase behaviour of these hydrocarbons now reveals that both effects are due to some peculiarity in one of two structures in which n‐alkanes may crystallize, viz. the Sβ‐modification. As a consequence, the thermodynamic properties of this solid modification show an alternation; this effect, in its turn, is responsible for the specific behaviour of the melting and transition point temperatures.It is to be expected that the other crystal structure, viz. Sα, and the liquid do not show similar peculiarities.
Recent trends in the study of complex compounds
Authors: Sharpe A. G. 
Published: September 2010

AbstractThree fields of complex chemistry which have attracted great interest during recent years are
The stabilisation of oxidation states by complex formation.
The correlation of magnetic and other physical properties with the structures of complexes as determined by X‐ray crystallography.
The factors which influence the reactivity of complexes, and the nature of substitution processes.
An attempt is made to review some of the major recent advances in each of these subjects, to indicate some of the difficulties involved, and to suggest in which direction further work is most likely to be profitable. Among the subjects to which reference is made are: recent work on complex fluorides; the stereochemistry of nickel and copper; the correlation of analytical uses with structure for metal derivatives of dioximes; and recent work on the mechanism of substitution in octahedral complexes.
Neuere Untersuchungen an komplexen Fluoriden
Authors: Hoppe R. 
Published: September 2010

AbstractEs wird über die Darstellung einiger bislang noch unbekannter Alkali‐und Bariumfluorometallate berichtet. Ausserdem wurden mehrere bereits bekannte Verbindungen dieser Reihe erneut dargestellt und untersucht.In vielen Fällen, nämlich bei der Darstellung der komplexen Alkalisalze, hat sich die von Klemm und Huss gefundene Methode der Fluorierung von Gemischen geeigneter binärer Salze (z.B. KCl + AgNO3) weiterhin bewährt; zur Erhaltung sehr homogener Präparate (insbesondere für magnetische Untersuchungen) ist es jedoch oft zweckmässiger, Komplexsalze entsprechender Zusammensetzung zu fluorieren.Die Darstellung der Bariumfluorometallate gelingt im allgemeinen nur auf dem zweiten Wege. Dieses auffällige Verhalten hängt damit zusammen, dass bei Alkalisalzen primär die sehr aktiven Alkalifluoride MeFx (1 < × <3) gebildet werden, während beim Barium nur das hochschmelzende, reaktionsträge BaF2 entsteht.Die Verbindungen wurden magnetochemisch, röntgenographisch und analytisch untersucht.
Complexes of the lower oxidation states of tungsten. II. Spectral data
Authors: Jonassen Hans B. , Cantor Stanley 
Published: September 2010

AbstractThe instability of the lower oxidation states of tungsten has been of considerable interest in recent investigations.One of the compounds which has been extensively investigated is K3[W2Cl9]. The present work was undertaken in order to determine the multiplicity of the tungsten‐tungsten bond from infrared absorption and magnetic data.
Di‐Isonitrilopalladium(O) compounds
Authors: Malatesta L. 
Published: September 2010

The di‐isonitrilopalladium(O) compounds: Pd(RNC)2 (R = phenyl, p‐tolyl, p‐anisyl) in which the metal is in a formal zero oxidation state, have been prepared.These compounds are of a type different from the ones with Ni and Cr as metals, e.g. Ni(RNC)4 and Cr(RNC)6, previously described by the author, and probably have a polymeric structure.
Ligand field theory of complex formation by ions of the first transition series, theoretical treatment: Data (ΔH and ΔS)
Authors: Griffith J. Stanley 
Published: September 2010

AbstractComplex formation is discussed in terms of a molecular orbital model, and the energies of pairing d electrons in octahedral complexes are given in terms of atomic spectral parameters. The results are used to interpret Pauling's magnetic criterion and the variation of the heat of formation of a complex with change of central metal ion.
Electrometric study on equilibria in sodium silicate solutions
Authors: Lagerström Gösta 
Published: September 2010

AbstractAggregation of the silicate ion has been studied by accurate pH titrations of sodium silicate‐sodium perchlorate solutions ([Na+] being kept constant) at constant [Si]‐concentration, z̄ v. pH‐curves ( z̄ = average charge per silica unit) were calculated from the experimental data. These curves could be explained by assuming the formation of “core + links” complexes of the general composition H3SiO4‐(H2SiO3)n. The data which cover a limited range are compatible both with the formation of a single complex (n = 2, probably a ring) and with an unlimited mechanism (n = 1, 2, 3….). Equilibrium constants for both mechanisms are given.
Studies on the formation of composite complexes by means of an extractive technique
Authors: Rydberg Jan 
Published: September 2010

AbstractFor the interpretation of the data obtained on the extraction of metal complexes to organic solvents from aqueous solutions of low and constant ionic strength, the following minimum number of variables has to be considered: the concentrations of the metal atom (M), main ligand (the base A‐), HA, OH−, H2O, organic solvent molecules (Org) and the temperature. This has been done in an attempt to determine the compostion of the composite complexes of type MAn(OH)p(HA)r(Org)•(H2O)t formed in a given system.In this complex s and t can be determined only in special cases, and it is not possible to distinguish by equilibrium methods between isomers with the same values for x = n + r and y = n + p. These isomers can be represented by the formula M(HA)x(H)−y.It can be shown that in principal a distinction can be made between complexes of the type MAn, MAn(OH)p or MAn(OH)p(HA)r.A general method to calculate formation constants for the complex M(HA)x(H)−y from extraction data has been developed. It is also shown that from a comparison of the distribution ratios of the metal between water and several different organic solvents it is possible to determine if the metal forms a complex with the organic solvent molecules.The equations have been applied on the distribution of U(VI) and Th between several different organic solvents and water in the presence of acetylacetone.
Why are some metal‐binding substances anti‐bacterial?
Authors: Albert Adrien , Rees C. W. , Tomlinson A. J. H. 
Published: September 2010

AbstractVery few of the common metal‐binding substances have anti‐bacterial properties, Nevertheless, 8‐hydroxy‐quinoline and its derivatives are powerful bactericides, and the anti‐bacterial action has been shown to depend on the intactness of the chelating structure1). Further, these substances are innocuous if traces of iron are removed from the testing medium2). The hypothesis has been evolved that they kill by transporting iron into the bacterial cell2).The examination of related substances 3) suggested that two factors are necessary to make metal‐binding substances anti‐bacterial, (a) a high stability constant of the iron complex, and (b) a high partition‐coefficient in favour of lipids, to assist penetration of the cell. In an attempt to test the validity of these assumptions, the required high partition‐coefficients were easily attained by inserting alkyl groups (C1 to C3). But high stability constants are uncommon, and cannot be predicted in advance of synthesis.In the course of the present work, several substances were examined from this point of view. Of these, 2‐mercaptopyridine‐N‐oxide is the most antibacterial. It has the intense and rapid action of 8‐hydroxyquinoline and acts by the same mechanism (transport of iron).
On the infrared spectrum of urea in the urea‐cetane complex
Authors: Stuart A. A. Verrijn 
Published: September 2010

AbstractThe spectral region of the N‐H stretching, frequencies of the urea‐cetane complex was investigated with the aid of polarized infrared radiation. A dichroism was observed similar to that found by Waldron and Badger in a study of the pure urea crystal. The differences between the two cases are discussed in terms of a “coupled oscillator” model. They are shown to be closely connected with the differences in hydrogen bonding in the crystals, as known from the X‐ray studies of A. E. Smith, and Vaughan and Donohue.
Studies on polarography: I ‐ Reduction of potassium permanganate at the dropping mercury electrode
Authors: Issa I. M. , Khalafalla S. E. , Issa R. M. 
Published: September 2010

AbstractReduction of the permanganate ion at the dropping mercury electrode is studied in acid, neutral, and alkaline solutions. As supporting electrolytes KCl, BaCl2, and Ba(NO3)2 together with the constituents of buffer solutions of pH 1, 3, 5, 7, 9, and 12 were used. The polarograms consist each of two waves; the first starts at zero potential and corresponds to the process Mn+7 → Mn+2, except in the phosphate buffer of pH 12. In this phosphate buffer it proceeds as Mn+7 → Mn+3. The second wave corresponding to the process Mn+3 → Mn or Mn+2 → Mn appears at ∼ pH 5 and higher. In alkaline solutions the first wave is split up into smaller waves, possibly corresponding to Mn+7 → M+4, Mn+4 → Mn+3, and Mn+3 → Mn+2.In acid solutions the Mn+2 → Mn wave disappears and is replaced by a hydrogen wave. Some irregularities observed in alkaline solutions are explained.
Chemistry of the sydnones. II
Authors: Earl J. C. 
Published: September 2010

AbstractAlthough the sydnones are converted to hydrazines by hot, moderately concentrated aqueous hydrochloric acid, more dilute acid is without effect on 3‐phenylsydnone. Chlorination and bromination can be effected in aqueous solutions of the corresponding acids, using either the halogens themselves or the alkali chlorates and bromates.
The reactivity of the bromine atom in methylsubstituted nitrobromobenzenes towards piperidine
Authors: van Berk P. , van Langen J. O. M. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractReaction rate constants are determined for the piperidino‐debromination of a number of derivatives ofortho‐ andpara‐nitro‐bromobenzene with one or two methyl groups as substituents. The results are discussed and compared with those obtained in the catalytic deacetylation of the corresponding nitroacetylamino compounds in an alkaline medium.
Hydrocarbures polycycliques aromatiques. I. Dérivés de substitution du 3,4‐9,10‐dibenzopyrène
Authors: Buu‐Hoï N. P. , Lavit Denise 
Published: September 2010

AbstractIl est montré que le 3,4‐9,10‐dibenzopyrène peut être formylé par la N‐méthylformanilide en 5‐formyl‐3,4‐9,10‐dibenzopyrène; le 5‐methyl‐3,4‐9,10‐dibenzopyrène, obtenu par réduction de ce dernier aldéhyde, peut à son tour être formylé, et le 8‐formyl‐5‐méthyl‐3,4‐9,10‐dibenzopyrène ainsi préparé est réductible en 5,8‐diméthyl‐3,4‐9,10‐dibenzopyrène. La réactivité des sommets mésoanthracéniques permet également de préparer le 5,8‐dinitro‐3,4‐9,10‐dibenzopyrène, lequel est réductible en 5,8‐diamino‐3,4‐9,10‐dibenzopyréne avec le chlorure de sulfuryle, on a le 5,8‐dichloro‐3,4‐9,10‐dibenzopyrène.
A liquid bath precision thermostat ranging from about 20° C to over 360°C
Authors: Smit W. M. , van Wijk H. F. 
Published: September 2010

AbstractA thermostat suitable for the checking of mercury thermometers is described. The bath liquid consists of a mixture of sodium and potassium. The thermostat can be used from temperatures somewhat above room temperature to over 360° C. Its accuracy is ± 0.002° C at 330° C. At lower temperatures the accuracy is better than ± 0.001° C. The thermostat attains equilibrium at any desired temperature within three hours.
Bromination and nitration of 2‐hydroxypyridine‐N‐oxide
Authors: van Ammers M. , den Hertog H. J. 
Published: September 2010

AbstractFrom the reaction mixtures obtained by brominating and nitrating 2‐hydroxypyridine‐N‐oxide the sole disubstituted products isolated were the 3,5‐derivatives. The course of the bromination and nitration of 2‐hydroxypyridine‐N‐oxide differs from the analogous reactions of 2‐hydroxypyridine only in an increased reaction velocity.
The energetics of highly charged spherical micelles as applied to sodium lauryl sulphate
Authors: Overbeek J. Th. G. , Stigter D. 
Published: September 2010

AbstractThe electrical free energy of micelle formation is treated for spherical micelles with a Gouy type double layer, allowing for high surface charge. Use is made of double layer computations carried out by Hoskin for spherical particles with high surface potential. A procedure is developed for interpolating between Hoskin's results. A correction is applied for the difference between the smeared out surface charge as in the model calculations and the actual assembly of discrete charges.From the equilibrium equation for micellization in which this electrical free energy occurs together with terms depending on the concentrations of free ions and of micelles the non‐electrical part of the standard free energy of micelle formation (W‐TΔSo) can be calculated.The method is applied to micelles of sodium lauryl sulphate in aqueous sodium chloride solutions. In this system W‐TΔSo is found to be nearly independent of micelle size and slightly above 1 kT per carbon atom in the chain. Comparison with other data on the free energy change in the transfer of aliphatic chains from water to non‐polar surroundings shows excellent agreement.
The reaction between bromoacetate and thiosulphate ions in dilute solution
Authors: Erkelens J. , Korvezee A. E. 
Published: September 2010

AbstractThe rate of the reaction between thiosulphate and bromoacetate in very dilute aqueous solutions has been redetermined. The variation of the rate constant with the ionic strength of the solution can be predicted from the “activated complex” theory combined with the Debye‐Hückel limiting law. In the concentration range where the latter is valid our data are in agreement with the theoretical relationship and with the most plausible reaction mechanism.
Chemistry of acetylenic ethers. XVIII: Reactions of ethoxyethynylcarbinols with amines
Authors: Postma J. C. W. , Arens J. F. 
Published: September 2010

AbstractEthoxyethynylcarbinols, which can be prepared from carbonyl compounds and metallic derivatives of ethoxyacetylene, react with amines in three different ways.Strongly basic amines like diethylamine mainly cause reaction A, dissociation of the carbinol into the carbonyl compound from which the carbinol was derived, and ethoxyacetylene (which reacts further with the amine used). Very weakly basic aromatic amines like p‐nitroaniline catalyze the rearrangement into α,β‐unsaturated esters (reaction B), whereas aromatic amines like aniline yield amides of β‐hydroxy‐acids with evolution of ethylene (reaction C).
The isothermal compressibilities of liquids
Authors: McGowan J. C. 
Published: September 2010

AbstractFor unassociated liquids, the following relationship between the surface tension (γ) and the isothermal compressibility (χT) is found

This relationship leads to an expression for the parachor (vp)

and to the following equation for the variation of isothermal compressibility with temperature (T)

where Tc is the critical temperature of the liquid, M its molecular weight, d1 its density and dg the density of the vapour in equilibrium with it; k is the Eötvös constant.
The mutarotation and ionization of D‐glucose in alkaline solution II
Authors: Los J. M. , Simpson L. B. 
Published: September 2010

AbstractMeasurements of the rate of mutarotation of D‐glucose in unbuffered alkaline solutions, with a pH meter, have been continued with a more sensitive instrument. All available data have been reinterpreted on the basis of the following assumptions:
(a) The mutarotation in alkaline solution of D‐glucose is first order in the glucose concentration and the specific rate constant is given by

(b) The catalytic constants kGα and kGβ are related by an expression derived from the Brønsted catalysis law

where c was taken as equal to 0.4.
It has been shown that the latter assumption (b) could eliminate the difficulty experienced in the preceeding communication 1) of a kOH value which was strongly dependent on the glucose concentration.The results provide new values for the catalytic constants of hydroxyl ions, of the α and β glucosate ions, and for the hydrolysis and ionization constants of α and β D‐glucose. Corresponding equations have been given.A critical discussion of the errors in the method has been included.The results prove, among other things, that the reason for the greater acidity of β D‐glucose than of the corresponding α form (as established in this investigation) lies in the considerable difference in entropy change upon ionization for the two different isomers.