bluuebunny/crossref_metadata_2025_split huggingface dataset:
The vulcanization of rubber with phenol formaldehyde derivatives
Authors: van der Meer S. 
Published: September 2010

AbstractReferring to the preceding article describing the methylene quinone theory of the vulcanization of rubber with phenol formaldehyde derivatives, in this paper the arguments in favour of that theory are considered in detail. The results of the investigations in question can be summarized as follows.
The vulcanizing properties of the pseudo‐phenol halides are based on the easy transformation of these compounds into methylene quinones with the liberation of gaseous hydrogen halide.
The vulcanizing properties of the phenol‐dialcohols are also based on the formation of methylene quinones as intermediates, however at higher temperatures only.
Phenol‐dialcohols vulcanize slowly, at temperatures lying only little below their decomposition temperatures, and yield comparatively good vulcanizates.Pseudo‐phenol halides vulcanize rapidly, at temperatures lying considerably below their decomposition temperatures, and yield comparatively poor vulcanizates.
The vulcanization temperature of 4,6‐di‐hydroxymethyl‐2‐methylphenol (about 200° C) is higher than that of 2,6‐di‐hydroxymethyl‐4‐methylphenol (about 155° C), as in the first case the vulcanization is based on the formation of an ortho‐methylene quinone as well as a para‐methylene quinone and in the second case on the formation of ortho‐methylene quinones exclusively. Generally these last compounds are formed more/easily than the para isomers.
The vulcanizing properties of 2,6‐di‐hydroxymethyl‐4‐methylphenol at 155° C are reduced by the addition of 4,6‐di‐hydroxymethyl‐2‐methylphenol, in consequence of the formation of molecular complexes which are unable to form ortho, but only para‐methylene quinones.
The vulcanizing properties of the phenol formaldehyde derivatives are entirely destroyed by hexamethylene tetramine, as that substance combines with the primarily formed methylene quinones.
The vulcanization reactions of the phenol formaldehyde derivatives are not based on the formation of an irregular knot of entangled rubber and resin molecules, but on primary chemical bonds between these two.
The vulcanizing properties of the esters of the phenol‐dialcohols as well as those of the pseudo‐phenol halides, are based on the formation of methylene quinones as intermediates with the liberation of acids. The higher fatty acid esters of 2,6‐dihydroxymethyl‐4‐methylphenol are unstable, showing the liberation of acids already at room temperature.
Compounds which may be supposed to be derived from phenol‐dialcohols by a change in their configuration do not show vulcanizing properties if the formation of methylene quinones is impossible. If a repeated formation of these intermediates is only possible to a very limited extent, as is the case with phenol‐monoalcohols, vulcanizing properties are also present on a minor scale.
Makromoleküle in Lösung
Authors: Hermans J. J. 
Published: September 2010

AbstractEs werden die von W. Kuhn und H. Kuhn erhaltenen Formeln für die Viskosität und die Strömungsdoppelbrechung mit den unsrigen verglichen. Es zeigt sich dabei von grosser Bedeutung, dass der Auslöschwinkel sehr empfindlich ist für geringe Abweichungen des Polymerisationsgrades von dem Mittelwert. Aus diesem Grunde lässt sich zur Zeit nicht entscheiden, welche Formeln den Vorzug verdienen.
Die Sedimentationsgeschwindigkeit Langkettiger Makromoleküle
Authors: Hermans J. J. 
Published: September 2010

The sedimentation velocity of a long‐chain molecule is greatly increased by the hydrodynamic interaction of its constituent parts. If Kuhn's model of randomly kinked molecules is accepted, the application of a formula obtained by Burgers leads to an expression for the sedimentation velocity which is shown to account for experimental results mentioned in the literature.This hydrodynamic interaction manifests itself in a way‐which illustrates the hydrodynamic meaning of the “undurchspülte Knäuel” assumed by Kuhn and makes his assumption very acceptable. It is emphasized, however, that this interaction is much less effective in the presence of a velocity gradient. This explains the experimental fact that various substances conform to Staudinger's viscosity rule, while at the same time their sedimentation constant is dependent on molecular weight.
Préparation et Structure du 2‐Acétylamino‐5‐Bromothiazol
Authors: Backer H. J. , Buisman J. A. Keverling 
Published: September 2010

AbstractPar bromuration du 2‐acétylaminothiazol, on obtient le 2‐acétylamino‐5‐bromothiazol, dont la structure est établie.
Photometric determination of micro‐quantities of mercury as mercury dithizonate
Authors: Reith J. F. , Gerritsma K. W. 
Published: September 2010

AbstractIt is possible to determine 2.5 to 250 γ of mercury photometrically by extracting the mercury salt solution with an excess of dithizon solution in chloroform and measuring the extinctions of the chloroform layer at 500 and 610 mμ. The amount of mercury is calculated from the volume of dithizon solution used and the extinctions E500 and E610 measured, thus standardization of the dithizon solution is unnecessary.The pure solution of the orange coloured mercury dithizonate in chloroform turns a dirty greenish orange in daylight, in direct sunlight it becomes bluish purple in a few minutes. The original colour is quickly recovered again in the dark. This reversible photochemical process is completely inhibited by acetic acid.
On the bromination of naphthalene: The influence of temperature and catalysts on the proportions of 1 and 2‐bromonaphthalene formed I
Authors: Suyver J. F. , Wibaut J. P. 
Published: September 2010

AbstractThe bromination of gaseous naphthalene in the presence of glass wool or pumice was investigated in the temperature range from 250° to 650° C. The content of 2‐bromonaphthalene in the mixture obtained was determined; the more highly brominated products were not investigated. It was found that from 250° to 300° a small amount of 2‐bromonaphthalene is formed; between 300° and 500° C the amount of 2‐bromonaphthalene increases rapidly with the temperature. At still higher temperatures the ratio of 1‐bromonaphthalene to 2‐bromonaphthalene changes only little and is approximately equal to unity.The bromination of liquid naphthalene without a catalyst was examined in the temperature ranges from 85° to 215° C. Under these conditions little 2‐bromonaphthalene is formed and the amount increases regularly with the temperature. This increase can be represented by the formula of Scheffer.Attention is called to the specific catalytic action of ferric compounds, by which not only in the bromination in the gas phase, but also in that in the liquid phase the formation of 2‐bromonaphthalene is considerably promoted.An example is given of the preparation of 2‐bromonaphthalene by the bromination of liquid naphthalene at 150° with ferric bromide as catalyst.
Préparation et Activité Sulfonamide de Quelques Aminosulfures et ‐Sulfones
Authors: Backer H. J. , Buisman J. A. Keverling 
Published: September 2010

AbstractPour étudier leur activité sulfonamide, les auteurs ont préparé quelques sulfures et sulfones mixtes des types 4‐NH2˙ C6H4 ˙ SR et 4‐NH2 ˙ C6H4 ˙ SO2R.
Raman spectra of the seven isomeric pentenes and quantitative analysis of two mixtures by means of the raman effect
Authors: Gerding H. , van Der Vet A. P. 
Published: September 2010

AbstractThe Raman spectra of the six open‐chain pentenes C5H10 and the spectrum of cyclopentene C5H8 are reported on. Polarization measurements of the latter compound were made and a short discussion of its symmetry is given.Measurements concerning the intensities of Raman lines were carried out for the quantitative analysis of a binary mixture of pentene‐1 and 2‐methylbutene‐1 and of a ternary mixture containing trans‐ and cis‐pentene‐2 and 2‐methylbutene‐2.
Die Bestimmung der quantitativen Zusammensetzung von Mischungen, welche als Komponente Mahlprodukte von Roggen und Weizen enthalten, insbesondere mit Hilfe einer Nephelometrischen Methode. II: Roggen, Weizen and Kartoffelmehl als Komponente
Authors: Openti E. C. , van der Lee T. 
Published: September 2010

AbstractNachdem in der Abhandlung ISehe H. M. R. Hintzer und J. van der Lee, Rec. trav. chim. 63, 53‐68 (1944).
) die Methodik der nephelometrischen Bestimmung von Mischungen von Roggen‐ und Weizenmehl behandelt wurde, wird in folgender Abhandlung beschrieben, in welcher Weise diese Methode nutzbar gemacht werden kann für die Untersuchung von Mischungen, die als dritte Komponente noch Kartoffelmehl enthalten.
On the structure of leucaenine (leucaenol) from leucaena glauca bentham
Authors: Bickel A. F. , Wibaut J. P. 
Published: September 2010

AbstractFrom the seeds of Leucaena glauca B, obtained from the Netherlands Indies, we isolated leucaenine which, under the name leucaenol, was first described in 1937 by Mascré, who determined for this compound the empirical formula C4H5O2N. We obtained about 16 g of pure leucaenine (melting point 226°–227° with decomposition) from 1 kg of seeds.From an electrometrical titration the molecular formula of the substance is found to be C8H10O4N2; leucaenine is an α‐amino acid in the molecule of which a pyridine ring substituted by hydroxyl occurs. By the action of dimethyl sulphate and alkali on leucaenine we obtained a compound C7H11O3N (I) which could be converted into a N‐methylhydroxypyridone having the composition C6H7O2N (II). This compound is not identical with N‐methyl‐6‐hydroxypyridone‐2 or with N‐methyl‐3‐hydroxypyridone‐2, which hitherto unknown pyridones were obtained by synthesis, and it is likewise not identical with the N‐methyl‐4‐hydroxypyridone‐2 (or N‐methyl‐2‐hydroxypyridone‐4) described by Späth. To the compound C6H7O2N therefore the structure of an N‐methyl‐3‐hydroxypyridone‐4 or of an N‐methyl‐5‐hydroxypyridone‐2 must be assigned; for the present we consider the first structure mentioned the more probable.Leucaenine itself must be considered as a β‐[hydroxypyridyl‐oxy] ‐α‐aminopropionic acid; the positions at which the hydroxyl group and the serine radical are substituted in the pyridine nucleus have not yet been determined, although it follows from our investigation that several positions are impossible. The most probable formula for leucaenine is in our opinion: β‐[3‐(4‐hydroxypyridyl)‐oxy]‐α‐aminopropionic acid. Since the compound isolated by us must therefore be classed among the naturally occurring amino acids we propose to call this substance leucaenine.The substance mimosine isolated by Renz and by Nienburg and Tauböck from the leaf stems of Mimosa pudica L. and of Leucaena glauca B is very probably identical with leucaenine.From experiments on animals it was found that the administering of leucaenine or of seeds of Leucaena glauca B to rats or mice did not cause the hair to fall out. This result is not in agreement with several statements in the literature, according to which larger mammals, such as horses and donkeys, showed loss of hair after being fed on seeds or leaves of the plant.
A method for calculating the polarizability of the particles of a substance from the index of refraction and the density of dilute solutions of that substance
Authors: Böttcher C. J. F. 
Published: September 2010

AbstractA formula is derived with the aid of which it is possible to compute the polarizability of the particles of a substance from measurements of the variations which the index of refraction and the density of a solvent undergo when a small quantity of the substance is dissolved in it.As an application of this formula the polarizabilities of the alkali and halogen ions are calculated, starting from the measurements by Heydweiller and others on dilute aqueous solutions of the alkali halides.
The reaction between phenylhydrazine and ω‐chloroacetophenone. (The reaction between ω‐halogenoketones and phenylhydrazine, V)
Authors: van Alphen J. 
Published: September 2010

AbstractThe compound obtained by Hess, the condensation product of phenylhydrazine and ω‐chloroacetophenone has been investigated and its properties can be explained by assigning to it the constitution 1: 3‐diphenyl‐(1: 2‐diazacyclobutene‐2).The structure of the compound obtained by Scholtz from phenylhydrazine and ω‐chloroacetophenone, has been elucidated and proved to be the bis‐phenylhydrazone of diphenacyl.
On the reactivity of the bromine atoms in brominated pyridines: The preparation of brominated 2‐ and 4‐aminopyridines
Authors: Den Hertog H. J. 
Published: September 2010

AbstractA description is given of the preparation and proof of the structure of nine brominated 2‐amino‐ and of three brominated 4‐aminopyridines.A survey is given of these two groups of pyridine derivatives, all the possible members of which are now known.In connection with the preparation of brominated aminopyridines by the action of ammonia on bromopyridines, the reactivity of the bromine atoms towards ammonia is discussed.Finally, in connection with one of the above‐mentioned preparations, an improved procedure is given for the synthesis discovered by Errera of 2,4‐dihydroxypyridine‐4‐carboxylic acid ethyl ester.
The Raman spectrum of the compound C6Cl6O
Authors: van Brederode H. , Gerding H. , Prins H. J. 
Published: September 2010

AbstractThe Raman spectrum of C6Cl6O, obtained by the reaction of C6Cl8 183° with sulphuric acid in glacial acetic acid, was determined for solutions in CCl4 and CS2.The Raman effect data prove the presence in the molecule of a C = O group. Further two intense v(C = C) frequency shifts have been found. Of the two C = C bonds indicated by the formula C6Cl6O, at least one is probably conjugated with the C = O group, as is shown by the rather low frequency value for v(C = O) in this cyclic compound.
A new method of preparing 1‐Halogeno‐ and 1‐Alkoxy‐2‐Amino‐4‐Nitrobenzenes
Authors: Blanksma J. J. 
Published: September 2010

AbstractThe method consists of converting the cyano group in 1‐halogeno‐ or 1‐alkoxy‐2‐cyano‐4‐nitrobenzenesPrepared according to H. Ph. Baudet, Diss. Leiden, 1920, pp. 16, 20 and 21. Rec. trav. chim. 43, 709 (1924).
into the amide grouping, by boiling with a dilute alkaline solution of 3% hydrogen peroxide. The amide is then converted into the corresponding amino‐compound by treatment with sodium hypochlorite or hypobromite. The intensely sweet 1‐alkoxy‐ and 1‐halogeno‐2‐amino‐4‐nitrobenzenes, so obtained, are identical with those obtained by partial reduction of the 1‐halogeno‐ and 1‐alkoxy‐2:4‐dinitrobenzenes so that a new proof of the structure of these compounds has been furnishedOther proofs of structure see J. J. Blanksma, Chem. Weekblad 9, 437 (1912); Rec. trav. chim. 59, 630 (1940).
. The formation of intensely sweet 1‐alkoxy‐2‐amino‐4‐nitrobenzenes from the corresponding amides, which are tasteless, can be used as a test for these amides.
Action Catalytique du Zinc Sur la Précipitation de sb ET SbSn dans les Alliages Riches en Plomb
Authors: de Decker H. C. J. 
Published: September 2010

AbstractWenn es in einer Legierung eine Komponente gibt, die bei höherer Temperatur immer besser löslich wird, so kann eine solche Legierung durch Erhitzen gegebenenfalls homogen gemacht werden. Nach Abschrecken bis auf eine viel niedrigere Temperatur bleibt dann der homogene Zustand zuerst metastabil erhalten. Im Laufe der Zeit spielt sich eine Alterung ab, welche schliesslich zur Ausscheidung der schwer löslichen Komponente führt, durch welche Ausscheidung der Gleichgewichtszustand erreicht wird. Am Anfang der Alterung steigt die Härte der Legierung. (Aushärtung).Es wurden mit einer Reihe von Legierungen, welche ungefähr 98% Pb enthielten, Untersuchungen ausgeführt. Es sind Sb und/oder Sn als Legierungsbestandteile vorhanden. Derartige Legierungen zeigen die oben genannten Erscheinungen. Ein Teil der Legierungen enthält ausserdem eine kleine Menge Zn. Die Zusammensetzung der Legierungen ist gegeben in Zahlentafel 1.Kleine Konzentrationen Zn (etwa 0.1%) hemmen ein Ansteigen der Härte und befördern die Ausscheidung in diesen Legierungen (s. Fig. 2 und Zahlentafel 2).Aus Literaturangaben geht hervor, dass geringe Mengen von As oder Cu die Aushärtung derartiger Legierungen beschleuningen ohne merkbare Beförderung der Ausscheidung.Aus den unterschiedlichen Tatsachen kann man folgern, dass die Aushärtung bei den untersuchten Legierungen stattfindet in der noch homogenen, metastabilen Phase und nicht mit dem Beginn der Ausscheidung verknüpft ist.Auch über den Einfluss der neben Sb vorhandenen Menge Sn lassen sich Folgerungen aus den Versuchen ableiten.
Amine salts of ethane αβ‐disulphonic acid
Authors: Blanksma J. J. 
Published: September 2010

Abstractαβ‐Dichloroethane (ethylene dichloride) gives with sodium disulphide in alcoholic solution the bitter, unpleasant smelling diethylene‐1: 2: 5: 6‐tetrasulphide, which on oxidation with nitric acid affords the odourless ethane αβ‐disulphonic acid1).In alcoholic solution this acid gives beautiful, odourless, crystalline salts with aniline, p‐toluidine and benzidine, which have a weakly acid but no bitter taste. The benzidine salt, like benzidine sulphate, is difficultly soluble in water.The substance responsible for the bitter taste and garlic‐like smell of diethylene tetrasulphide (1:2:5:6‐tetrathiacyclooctane), does not entirely disappear on oxidation with nitric acid, which produces sulphuric acid as well as ethane αβ‐disulphonic acid. Neutralisation with barium carbonate produces the tasteless barium ethane disulphonate and barium sulphate on which the bitter substance is adsorbed.
The synthesis of “vitamin A acid”, a biologically active substance
Authors: van Dorp D. A. , Arens J. F. 
Published: September 2010

AbstractBy dehydration and subsequent saponification of the reaction product obtained from β‐ionone and γ‐bromocrotonic ester we prepared β‐ionylidene crotonic acid III, which substance was transformed into the “C18 ketone” IV by means of lithium methyl. From this ketone we prepared “vitamin A acid” VII, by means of a Reformatski reaction with methylbromoacetate. This substance proved to have a strong vitamin A activity.
Syntheses of polychloro compounds with aluminium chloride. VI: The elimination of hydrogen chloride from polychloro compounds and the formation of cyclic compounds. The synthesis of perchlorocyclopentadiene
Authors: Prins H. J. 
Published: September 2010

AbstractThe present paper describes several instances of the catalytic liberation of hydrogen chloride from polychloro compounds by the action of aluminium chloride and the subsequent formation of five‐membered rings. The formation of these rings furnishes a simple synthesis of perchlorocyclopentadiene.It is shown that chloroform is added to perchlorocyclopentadiene, giving a nona‐chloromethylcyclopentene which is also formed when trichloroethene is acted upon by chloroform at the boiling temperature of the latter.The reaction between perchlorocyclopentadiene and sulphuric acid at different temperatures is described, as also the reaction between octochloropentadiene‐1,3 and the same reagent.
The vapour pressure of solutions saturated with silver nitrate and with lead nitrate
Authors: Dingemans P. , Dijkgraaf L. L. 
Published: September 2010

AbstractThe vapour pressure of the four‐phase equilibrium solid AgNO3‐solid Pb(NO3)2‐saturated solution‐water vapour was measured from 10° C to the end point of this four‐phase line. This end‐point is the eutectic of the binary system AgNO3‐Pb (NO3)2. This eutectic was subjected to exact investigation; the eutectic temperature was found to lie at 203.1° C, while the eutectic melt consists of 92.8 percent by weight of AgNO3 and 7.2 percent by weight of Pb (NO3)2.The measured vapour pressure line appears to possess 2 stable maxima, namely at 155.8°C and at 163.1° C; the corresponding values of the vapour pressure are 824 and 822 mm Hg, respectively.This system exhibits the phenomenon of 2 boiling points at atmospheric pressure, namely at 140.9° C and at 176.1° C.Neither the presence of 2 stable maxima, nor the occurrence of 2 boiling points (at 1 at) had till now ever been observed in solutions saturated with two salts.
Lattice structure of the free surface of alkali halide crystals
Authors: Verwey E. J. W. 
Published: September 2010

AbstractCalculations have been made of the lattice distortion at the free crystal surface of the cube face of alkali halide crystals on the basis of Born's lattice theory, with the result that the displacement of the positive surface ions in a direction perpendicular to the surface differs considerably from that of the negative. A kind of ionic double layer is formed with the negative ion pointing away from the crystal. The corresponding dipole is more or less compensated by the dipole moment induced in the negative ions. This distortion lowers the surface energy as is illustrated by the calculation for the case of NaBr.
Flocculation and peptization in oil as dispersion medium
Authors: van der Minne J. L. 
Published: September 2010

AbstractExperiments on the flocculation of suspensions in a mineral oil show that high viscosity gives rise not only to low flocculation velocity but also to very slight adhesion of the particles. In a mineral oil as a viscous non‐aqueous liquid the influence of viscosity and temperature on the kinetics of colloidal phenomena can be investigated over a much wider range than in water.The effect of peptizers is investigated and a case is described in which two peptizers counteract each other. This is remarkable in view of the fact that the current explanation involving ions of opposite charge cannot be given.
A remark on the determination of surface areas by adsorption methods
Authors: de Boer J. H. 
Published: September 2010

AbstractAlthough adsorption isotherms of iodine on barium chloride or calcium fluoride layers show a pronounced sigmoid shape, the adsorption is not of a multimolecular character. The application of the Brunauer‐Emmett‐Teller method leads in these cases to values for the surface areas which are 2 to 4 times too small.
A simple capillary viscosimeter
Authors: van Gils G. E. 
Published: September 2010

AbstractA pipette viscosimeter is described which can easily be cleaned and, as far as accuracy is concerned, is almost equal to the Ostwald viscosimeter.In the theoretical part the maximum velocities permissible are calculated for capillaries with different diameters and for water at 30° C.From this the lowest viscosities permissible and the lowest flowing times permissible are calculated.
Note on a “precursor” of niacine
Authors: Roggen J. C. 
Published: September 2010

AbstractThe precursor of nicotinic acid discovered in wheat bran by a micro‐biological method in the United States is different from the 3‐pyridine derivative described by us possessing a complex side‐chain and occurring in human urine. In the alcoholic extract from wheat bran we could find chemically only nicotinic acid and no pyridine derivative of the structure type of the compound found in urine.Simple directions are given for the chemical determination of niacine in all possible milling fractions of the grainkernel.
Note on the reaction between pyridine and benzyl magnesium chloride
Authors: Veer W. L. C. , Goldschmidt  
Published: September 2010

AbstractThe Grignard reaction between pyridine and benzyl magnesium chloride does not lead to the formation of 2‐benzylpyridine, as has been described by Bergmann and Rosenthal, but to 4‐benzylpyridine.
The activity of ions in suspensions. I. On the activity of several cations in dusarite suspensions
Authors: Schuffelen A. C. , Barendregt T. 
Published: September 2010

AbstractThe activity of the ions was measured in a number of dusarite suspensions containing varying quantities of adsorbed K, Mg and Ca. It was found to be very small in dense suspensions. With equal occupation of the adsorbent the average relation between the activities of K, Mg and Ca is as 25: 2.3: 1. The relation between the ions expressed in activities is quite different from that expressed in true concentrations.