bluuebunny/crossref_metadata_2025_split huggingface dataset:
The reactivity of bromine atoms in brominated pyridines. The preparation of 3‐acetylamino‐5‐ethoxypyridine from 3,5‐dibromopyridine
Authors: den Hertog H. J. , Falter A. W. M. , van der Linde A. 
Published: September 2010

Abstract3‐Acetylamino‐5‐ethoxypyridine was prepared by converting 3,5‐dibromopyridine with sodium ethylate into 3‐bromo‐5‐ethoxypyridine, allowing this substance to interact with ammonia and acetylating the aminoethoxypyridine thus formed with acetic anhydride.
The reactivity of bromine atoms in brominated pyridines. The action of sodium methylate on 2,4,6‐tribromopyridine
Authors: den Hertog H. J. 
Published: September 2010

AbstractThe action of sodium methylate on 2,4,6‐tribromopyridine is described. The bromine atoms are very easily replaced by methoxyl groups, in the order 4, 2, 6. A proof of structure is given for each of the substances formed.
Investigations on glycidyl ethers, I. The synthesis of aromatic bisglycidyl ethers
Authors: Werner E. G. G. , Farenhorst E. 
Published: September 2010

AbstractThe synthesis of aromatic bisglycidyl ethers from epichlorohydrin and bivalent phenols under the influence of alkali has been investigated. Hydroquinone bisglycidyl ether has been separated into two diastereoisomers.
Condensation reactions of ketones with hydroxymaleic anhydride: Transformation of the condensation products into α,β‐unsaturated aldehydes
Authors: van Dorp D. A. , Arens J. F. 
Published: September 2010

AbstractKetones can be condensed with hydroxymaleic anhydride under the influence of hydrogen chloride to give acids of the typemagnified imageThe elimination of two molecules of carbon dioxide gives rise to aldehydesmagnified imageIn general the method seems unsuitable, however, for the preparation of large quantities of these aldehydes.
Rate of Dissolution of Solid Substances Part I. Rate of mass transfer in granular beds (Physical dissolution)
Authors: van Krevelen D. W. , Krekels J. T. C. 
Published: September 2010

AbstractRate of mass transfer in granular beds has been studied by determining the rate of dissolution of benzoic acid in water and aqueous glycerol solutions and of sulphur in benzene. For liquid‐continuous flow and film‐like flow, mass transfer coefficients could be correlated by dimensionless equations
Alkylation of isopentane with isopentene in the presence of concentrated sulphuric acid
Authors: van Steenis J. , Waterman H. I. 
Published: September 2010

AbstractAlkylation of isopentene with isopentane and sulphuric acid can be accomplished in two minutes reaction time, provided that the reacting substances are emulsified during the reaction.The most favourable ratio of the reacting substances (volumes) is about 5 of isoparaffin; 2 1/2 of sulphuric acid; 1 of olefin. If the reaction conditions are favourable to the formation of polymer hydrocarbons from the olefin (bad mixing) a long reaction time is required to obtain a “good alkylate”.The formation of products with an anomalous number of carbon atoms proceeds simultaneously with the formation of pure alkylate (C10). With isopentene the formation of polymer‐sulphuric acid esters is the first step in the formation of alkylate.
A useful variant of the two‐line method for calibration of photographic emulsions
Authors: Schmidt R. 
Published: September 2010

AbstractFundamentals of the two‐line method of emulsion calibration, in which the characteristic curve is derived from densities of two spectrum lines of constant relative intensity, photographed at different densitiy levels, are discussed.It has been found, that the principles of this method can be applied to the presentation of data obtained by any method of calibration, which is based on an intensity pattern following a geometrical series. The scope of the method is considerably widened by substitution of densities (\documentclass{article}\pagestyle{empty}\begin{document}$ \log \,\frac{{{\rm A}_{\rm o} }}{{\rm A}} $\end{document}) by densities transformed according to Seidel (\documentclass{article}\pagestyle{empty}\begin{document}$ \log \,(\frac{{{\rm A}_{\rm o} }}{{\rm A}} - 1) $\end{document}).
The dimensions of charged long chain molecules in solutions containing electrolytes
Authors: Hermans J. J. , Overbeek J. TH. G. 
Published: September 2010

AbstractIf a long chain molecule in a solution carries electric charges, the statistical coil is inflated, and the average square of the distance between the ends of the chain is larger than in the uncharged state. For a number of properties the determining factor is the value of ∑k (r2k)av, where rk is the distance between the k'th link in the molecule and the centre of gravity. This quantity is proportional to the square of the effective radius and is related to the square of the distance between the ends by a simple formula (section 2), provided the radius of the coil is small compared with the length of the extended chain.In section 3 the electrical free energy of the molecule is derived as a function of effective radius on the assumption that no electrolytes are present. This free energy determines in its turn the average dimensions of the coil.In section 4 a similar theory is developed for charged polymer molecules in the presence of electrolytes. The change of the effective radius with the charge on the polymer and the concentration of the electrolytes is calculated. In the limit of high electrolyte content the equilibrium between the interior and the exterior of the polymer coil may be considered as a Donnan equilibrium.
Spectrophotometrical determination of carbon monoxide in blood
Authors: Pieters H. A. J. , Hanssen W. J. 
Published: September 2010

AbstractIn order to determine whether a light case of poisoning is due to carbon monoxide, we must be able to demonstrate its presence and to determine its concentration in the patient's blood. In the method developed by Sayers and YantR. R. Sayers and W. P. Yant, Technical Paper 373 D.O.C. Bureau of Mines (1925).
tannin is added to the blood sample, by which a red precipitate is formed. The colour of the sample is compared with a series of blood‐samples containing known quantities of carbon monoxide. This method takes a long time, a sample of carbon monoxide‐free blood must be available and the accuracy is about 5% CO at the utmost. As the absorption spectra of CO‐haemoglobin (CO‐Hb), oxyhaemoglobin (O2‐Hb) and haemoglobin (Hb) are different, it is possible in principle to determine the CO in blood spectrophotometricallyK. Hinsberg, Z. Anal. Chem. 121, 435 (1941).
.We have examined the following factors:

The wave lengths at which the absorption by the components Hb, O2Hb, COHb is maximal and minimal.
The reproducibility of the results obtained with blood‐samples of different origin saturated with a) CO and b) O2.
The stability of COHb in blood

haemolysed with sodium carbonate
haemolysed with saponin
treated with air.

We have determined the extinctions at two wave‐lengths and derived the CO‐concentration from the quotient of the extinctions.
A procedure is described.
Nouveaux α, β, β‐triaryléthènes substitués
Authors: Buu‐Hoï Ng. Ph. , Hoán N. G. , Lecocq J. , de Clercq M. 
Published: September 2010

AbstractDans ce travail, on décrit plusieurs nouveaux α,β,β‐triaryléthènes substitués qui ont été synthétisés dans le but d'examiner certaines de leurs propriétés physiologiques telles que le pouvoir oestrogène. La condensation avec le cyanure de benzyle sodé de diverses diarylcétones conduit à une série d'α,β,β‐triarylacrylonitriles appartenant à des familles variées (benzène, naphthalène, acénaphthène, diphényle, etc……). Dans certain cas, les 2 stéréoisomères prévus par la théorie ont pu être effectivement isolés; en outre, il a été observé que les cétones dirivées du noyau thiophène telles que le 2‐benzoylthiophène ou le 3‐benzoyl‐2,5‐thioxène ne se condensent pas avec le cyanure de benzyle sodé à l'amidure. Enfin, des α,β,β‐triaryléthènes et α‐bromo‐α,β,β‐triaryléthènes à noyau naphtalène, acénaphtène, diphényle, et pyrrole, ont été également synthétisés par les méthodes habituelles en vue de leur étude physiologique.
Relations between refraction, density and structure of series of homologous hydrocarbons. I. Empirical formulae for refraction and density at 20°C of n. alkanes and n. alpha‐alkenes
Authors: Smittenberg J. , Mulder D. 
Published: September 2010

AbstractIn studying the relations between physical constants of pure hydrocarbons, it was found that in many cases it is possible to express the constants of hydrocarbons belonging to a homologous series by an empirical formula of the type: x = x∞ + k/(c + z), where x represents the physical constant of a hydrocarbon, containing c carbon atoms, x∞ the limit of this physical constant at an infinite number of carbon atoms, and k and z empirical constants, characteristic for the series.Relations of this type are very valuable for control of purity of available hydrocarbon‐samples, for predicting the constants of unknown members of the series and for the analysis of hydrocarbon‐mixtures, particularly in the regions of higher molecular weight, where direct measurements of physical constants of individual hydrocarbons are scarce.This first publication of a series gives formulae of the above‐mentioned type for refraction and density at 20° C of n‐alkanes and n‐alpha‐alkenes, and linear relations between these two constants for both series.
Researches on plant growth regulators XIV. The influence of synthetic plant growth substances on lipoid monolayers
Authors: Havinga E. , Veldstra H. 
Published: September 2010

AbstractIn connection with the hypothesis that plant growth substances do not exert their growth promoting activity by a chemical reaction proper (e.g. functioning as redox‐catalysts) but by a more physical type of action on certain structures in the living cell, experiments were made on the influence of these compounds on monolayers of lecithin or oleic acid spread on aqueous solutions.It was found that apparently plant growth substances penetrate into and accumulate in such monolayers, their influence generally consisting in seemingly increasing the molecular area in the film. In some cases (decahydro‐naphthylacetic acid or undecanoic acid in the hypophases) very peculiar curves were obtained.The activity of a number of compounds tested in this way may be understood by considering the balance between the lipophilic part of the molecules and the hydrophilic carboxyl group.Although the type of action proved to be qualitatively as expected, a parallelism between the growth promoting activity of the compounds and their influence on these simple surface layers does not exist.Further detailed studies must provide an answer to the question whether the difference between the action in the model systems and in vivo might be caused by the apparently much too simple and aspecific composition of the films used, or whether, with the ideas put forward inH. Veldstra, Enzymologia 11, 97, 137 (1944).
, the physiological action has been simplified too much.
Preparation and some properties of diethylsilazines
Authors: de Man W. , van Steenis J. , Waterman H. I. 
Published: September 2010

AbstractDiethyldichlorosilane reacts with dry ammonia to give hexaethylcyclotrisilazine. Intermediates in this reaction are linear ethylsilazines which may contain chlorine atoms.The silazines decompose under the influence of moisture into NH3, diethylsilanediol and silicones.The preparation of diethyldichlorosilane from silicon tetrachloride and ethylmagnesium bromide has been improved.
Nitration of 3,5‐diethoxypyridine
Authors: den Hertog H. J. , van Weeren J. W. 
Published: September 2010

AbstractKönigs, Gerdes and Sirot have prepared a 3,5‐diethoxy‐dinitropyridine by nitrating 3,5‐diethoxypyridine. On repeating this experiment we have obtained a mono‐nitro‐derivative. We have proved that in this compound the nitro group is introduced into the 2‐position.When the 3,5‐diethoxy‐2‐nitropyridine is nitrated further the dinitrocompound described by Königs et al. is obtained. The nitro groups in this compound are in the 2‐ and 6‐positions.
The swelling of cellulose xanthate gels in dilute salt solutions
Authors: Vermaas D. , Hermans J. J. 
Published: September 2010

AbstractA theory is developed which connects the degree of swelling of a polymer network bearing ionogenic groups with the electrolyte concentration in the swelling medium.It is based on the assumption of an electrolyte distribution according to a Donnan equilibrium between the gel and the surrounding liquid on the one hand, and on the application of a modified Flory‐Rehner equation to the dependence of the free energy of dilution on the degree of swelling on the other hand.This theory is applied to the swelling of cellulose xanthate gels in neutral salt solutions. The following conclusions are reached.
The theoretical relation between the degree of swelling q and the electrolyte concentration c has the form q5/3 = B/βλc + (1‐K)/2 β, where B, β and K are constants related to fundamental physical properties of the swollen network; λ is a valency factor of the electrolyte studied.
In agreement with this formula the experimental q5/3‐ 1/λc plots are linear at moderate degrees of swelling and fairly independent of the electrolyte used. An explanation is given for deviations from linearity observed in highly swollen systems.From the slope of the experimental swelling curves it is concluded that the network consists of short chains.
Apart from the influence of the valency of the ions there exists also a lyotropic influence of the ions on the swelling of the gel.
The strong dependence of swelling on the xanthate ratio of the gel is in quantitative agreement with the effect predicted by theory.
The determination of acetic acid and propionic acid in bacteriological culture media
Authors: Tasman A. , Smith L. 
Published: September 2010

AbstractThe problem of determining small quantities of acetic acid and propionic acid in bacteriological culture media is discussed. The necessary conditions with regard to accuracy, are treated in detail, particularly in connection with the publication of van de Kamer.So called “half distillation percentages” of acetic acid and propionic acid mixtures varying from 100% acetic acid to 100% propionic acid were determined experimentally and are given in the form of a table and a graph. The distillation technique and the apparatus used are accurately described. The values found are not to be considered as “constants” for the acids in question but depend very closely on the standardised distillation technique actually used.The effect of the total acid concentration was clearly noticeable, and indeed, contrary to what is stated in the investigations of Virtanen and Pulkki, this effect was most marked for 100% acetic acid and mixtures rich in this acid. The concentration effect decreased for mixtures containing large amounts of propionic acid and could be neglected for 100% propionic acid.On the basis of these results an analytical technique is described which makes it possible to determine small quantities of acetic acid and propionic acid (varying from 0.40–1.75 grams of these acids in 2000 ml of medium) with a very satisfactory accuracy.This method has been tested experimentally on unknown quantities of these acids and the results obtained are given in a table.
Some urethane and diureide derivatives of α, β‐diarylethylamines
Authors: Neish W. J. P. 
Published: September 2010

AbstractSome α,β‐diarylethylamines have been prepared. They react with ethyl chloroformate to yield N‐substituted ethyl carbamates and with hexa‐methylene diisocyanate to give diureides. The new carbamates and ureides are to be investigated as possible chemotherapeutic agents for cancer.
A new method for the preparation of derivatives of 2,2′‐dipyridyl
Authors: den Hertog H. J. , Mulder B. 
Published: September 2010

AbstractWhen 2,6‐dibromo‐3,5‐diethoxypyridine is shaken with a mixture of ferric bromide and bromine in sunlight at 0°, it is converted in a yield of 95‐100 % into a derivative of 2,2′‐dipyridyl, i.e. 6,6′‐dibromo‐3,3′,5,5′‐tetraethoxy‐2,2′‐dipyridyl. It is shown that this reaction is a reversible process.The structure of 6,6′‐dibromo‐3,3′,5,5′‐tetraethoxy‐2,2′‐dipyridyl is proved by its formation and by the fact that 2,2′‐dipyridyl was obtained when the bromine atoms and the ethoxy groups were eliminated.6,6′‐Dibromo‐3,3′,5,5′‐tetraethoxy‐2,2′‐dipyridyl can be split up by allowing it to react with a mixture of sulphuric acid and fuming nitric acid, 6‐bromo‐3,5‐diethoxy‐2‐nitropyridine being formed. The last mentioned compound was converted into the dipyridyl derivative again when it was shaken with ferric bromide and bromine.
Synthesis of ketones by the action of α‐picolyl‐lithium on nitriles
Authors: Wibaut J. P. , de Jong J. I. 
Published: September 2010

AbstractThe action of α‐picolyl‐lithium on benzonitrile, acetontrile and α‐cyanopyridine is described. The ketimides of α‐picolyl phenyl ketone, α‐picolyl‐methyl ketone and α‐picolyl α‐pyridyl ketone are the primary products from which the corresponding ketones are eventually obtained. A method of preparation for α‐pyridyl α‐picolyl ketone, which is a new compound, is described.
Substituted ammonium carbamates from α,β‐diarylethylamines
Authors: Neish W. J. P. 
Published: September 2010

AbstractTwo new compounds believed to be substituted ammonium carbamates have been prepared by reacting α,β‐diphenylethylamine and α‐(4‐methoxy‐phenyl)‐β‐phenylethylamine with carbon dioxide.
3‐Methyl‐2‐butene carbonitrile
Authors: Ultée A. J. 
Published: September 2010

AbstractA method is described by which 3‐methyl‐2‐butene carbonitrile, CH3. C(CH3): CH.CH2CN, can be made more simply and in better yield than by the known method.The addition products of hydrogen chloride and isoprene, the primary hydrochloride, CH3.C(CH3): CH.CH2Cl and the tertiary hydrochloride, CH3.C(CH3)Cl.CH: CH2, give about 50% of the theoretical yield of the nitrile when treated with cuprous cyanide in benzene solution.
Ueber Dekahydroyobyrin und Tetrahydroyobyrin
Authors: Wibaut J. P. , Wibaut‐van Gastel A. J. P. , Buizer F. G. 
Published: September 2010

AbstractDie katalytische Reduktion des Yobyrins mit Platin‐Oxyd als Katalysator wird quantitativ untersucht. Die Reduktion verläuft in zwei Stufen: zuerst bildet sich ein Tetrahydroyobyrin und danach das Dekahydroyobyrin, das schon vorher von Wibaut und van Gastel beschrieben worden ist. Ein Hexahydroyobyrin bildet sich unter diesen Bedingungen nicht. Die ultravioletten Absorptionsspektra des Yobyrins, des Tetrahydroyobyrins und des Dekahydroyobyrins wurden bestimmt.
The bromination of naphthalene III.: The influence of temperature and catalysts on the proportion of α‐ and β‐bromonaphthalene formed; the equilibrium α‐ ⇌ β‐bromonaphthalene
Authors: Wibaut J. P. , Sixma F. L. J. , Suyver J. F. 
Published: September 2010

AbstractThe bromination of naphthalene vapour in the presence of ferric compounds on pumice as a carrier has been studied between 250° and 650°. The ratio of α‐: β‐monobromonaphthalene has been determined in the reaction product. More β‐isomer is produced under the influence of the catalyst than in the non‐catalysed bromination. The same holds also for the bromination of liquid naphthalene under the influence of ferric chloride, ferric bromide or ferrous bromide between 85° and 215°.The effect of the catalyst on the composition of the reaction product is a result of the reversibility of the reaction between bromine and naphthalene under these conditions. Although the equilibrium C10H8 + Br2 ⇌ C10H7Br + HBr, lies well over on the bromonaphthalene side, nevertheless an equilibrium between α‐ and β‐bromonaphthalene can be set up indirectly. The liquid equilibrium α‐ ⇌ β‐bromonaphthalene has been studied and the displacement of the equilibrium ratio with the temperature determined.
The mechanism of the catalytic alkylation of olefines and isoparaffins
Authors: Caviët M. , van Steenis J. , Waterman H. I. 
Published: September 2010

AbstractA discussion is given of the reactions which occur in the catalytic alkylation of olefines and isoparaffins, taking into account the polymerizing tendency of the reacting olefines under the conditions applied in the alkylation. Carbonium ions are intermediates in this reaction.
Amides IV: The use of diacetimide in the Perkin reaction
Authors: Polya J. B. , Tardrew P. L. 
Published: September 2010

AbstractDiacetimide may replace acetic anhydride in the Perkin reaction. Benzaldehyde and diacetimide yield cinnamamide with or without basic catalysts in good yield at 200‐220°. At 180° appreciable amounts of benzylidene bisamides are obtained, mainly benzylidene acetamide cinnamamide and benzylidene biscinnamamide.
Synthesis of vitamin A
Authors: Arens J. F. , van Dorp D. A. 
Published: September 2010

Abstract“C18‐ketone” I has been converted into vitamin A‐aldehyde VI by the method involving the use of ethoxy acetylene. This aldehyde has been reduced to vitamin A by means of either Al‐isopropoxide and isopropanol, or with LiAlH4. Also vitamin A acid II could be converted into vitamin A by means of LiAlH4.
La p‐Hydroxypropiophénone, Ses Analogues et Leurs Dérivés
Authors: Buu‐Hoï Ng. Ph. 
Published: September 2010

AbstractDans ce travail, on étudie la chimie de la p‐hydroxypropiophénone et de ses dérivés, ainsi que celle des composés analogues dans la série du naphtalène, en particulier des 6‐acyl‐2‐naphtols. De nombreuses réactions ont éré effectuées sur ces corps: transposition de Claisen, réduction de Clemmensen, réactions de Pfitzinger, de Fischer, etc. …. De nombreuses substances nouvelles ont été obtenues, en particulier des 6‐alkyl‐2‐naphtols, des 6‐acyl‐2‐naphtols et leurs éthers, des quinoléines, et des indoles portant des fonctions phénol ou éther‐phénolique. Plusieurs composés mentionnés dans ce travail ont fait ou font l'objet d'études biologiques et cliniques.
The copolymerisation of styrene and methyl methacrylate, styrene and butyl acrylate
Authors: Arlman E. J. , Melville H. W. , Valentine L. 
Published: September 2010

AbstractThe copolymerisations of styrene and methyl methacrylate, styrene and butyl acrylate, induced by the photo decomposition of benzoyl peroxide, have been studied and a full kinetic analysis of the reaction is presented. The introduction of small amounts of styrene lowers both the rate of initiation and the rate of copolymerisation to a marked extent, but further additions of styrene have relatively little effect. From a knowledge of the rate of initiation, derived from osmotic molecular weight data, and the overall rate, all the rate coefficients for the copolymerisations have been calculated. The termination constant for the reaction between styrene and methyl methacrylate radical (ktab = 2.06. 108) is much larger than that for styrene (ktaa = 8. 106) or methyl methacrylate (ktbb = 2.7. 107). Similarly for styrene (A)‐butyl acrylate (B), ktab = 5.7. 107 is much larger than ktaa = 8. 106 or ktbb = 1.8. 104. The derivation of these velocity constants is discussed critically, and a possible explanation of the large “crossed” termination constant, ktab, is offered, in terms of polar attractions of the two radicals.