bluuebunny/crossref_metadata_2025_split huggingface dataset:
Researches on plant growth regulators XXI. Structure/activity VI. Halogenated benzoic acids and related compounds
Authors: Veldstra H. 
Published: September 2010

AbstractOn account of the high activity reported for 2,3,6‐trichlorobenzoic acid (Bentley J. A. Bentley, Nature 165, 449 (1950).
)), at first sight lacking the spatial relation between—COOH group and ringsystem occurring in the active compounds known until now, the series of substituted benzoic acids was studied more closely. From the six isomeric trichlorobenzoic acids, now investigated in the pea‐test, only the 2,3,6‐trichloro acid proves to be highly active. From their U.V.‐absorption spectra it is deduced that with the di‐ortho (2,6) substituted acids steric inhibition of resonance occurs. In this way the tendency of the molecule to occur in a flat form on account of conjugation is counteracted. Consequently in the undissociated acid the dipole vector of the —COOH group will be at an angle with the plane of the ringsystem. For this reason the active substitued benzoic acids are considered in essence to be equivalent to the types of active compounds studied before, realizing a three‐dimensional amphipatic structure in a special way, namely by steric inhibition, especially of factors favouring coplanarity. 2,6‐Dichlorobenzoic acid, showing the same inhibition, is found to be physiologically active too and arguments are given that very probably the weak activity of α‐naphthoic acid has to be explained along the same lines. When in the latter acid the steric inhibition of resonance is intensified (as appears from the U.V.‐spectra) by chlorine‐substitution in the β‐position, for the resulting β‐chloro‐α‐naphthoic acid an increased activity is found, this being practically the same as that of 2,3,6‐trichlorobenzoic acid.
L'influence du Bromure D'hexadecyltrimethylammonium sur L'inhibition de la Respiration des Levures Causée par des Ions Metalliques
Authors: Massart L. , Schoon J. 
Published: September 2010

AbstractLe but de cette recherche est de voir si le mécanisme d'action des cathions toxiques est basé sur un même principe et s'exerce au même endroit. Pour mettre ces faits en évidence il est fait appel au bromure de cétyltriméthylammonium, cathion organique, qui exerce son activité en premier lieu à la surface cellulaire et qui sert en somme comme agent différenciant.
Properties and reactions of molecules at interfaces I. Theoretical remarks on ionic concentrations in the neighbourhood of monolayers containing charged groups)
Authors: Havinga E. , den Hertog‐Polak M. 
Published: September 2010

AbstractThe calculation of the electric potential and the ionic concentrations in the neighhourhood of a monolayer containing fatty acids or other, partially ionized, organic acids is discussed in order to get a basis for the understanding of reaction rates in unimolecular layers. The systems tinder connsideration show several features allowing straightforward theoretical reasoning. It seems difficult however to reach a detailed description without further experimental study. Therefore a simplifying treatment using the well‐known Gouy‐Chapman method is deemed to he acceptable at this stage to serve as a lead in experimental research.
Properties and reactions of molecules at interfaces II. Chemical analysis of surface layers obtained by spreading a fatty acid on hypophases of varying ph and ionic composition)
Authors: Havinga E. 
Published: September 2010

AbstractThe analysis of stearic acid/stearate monolayers. spread on hypophases of varying concentrations of H+. Na−, Ca−+, Mg++., (Cu++), is described. A discussion of the results is given. Comparing them with the theoretical relations formulated in the preceding paper.
Influence of organic compounds on soap and phosphatide coacervates XVII): Preliminary notes on the action of disubstituted benzene derivatives on soap coacervates
Authors: Booij H. L. 
Published: September 2010

AbstractThe action of o‐, m‐, and p‐isomers of disubstituted benzene derivatives on soap coacervates depends inter alia on the interaction of the groups. With benzene derivatives with a hydrophilic “anchor” group and a hydro‐phobic second substituent we find the series p > m > o. When the second substituent is a chlorine atom the same series appears in some cases, in other cases (e.g. chloroanilines) the sequence is reversed. Then it appears that the second group possesses a more hydrophilic character. The “anchor” group is in this case an electron donor, while the chlorine atom is electron attracting. The action of other isomeric benzene derivatives may be explained from the same point of view.
Thermal quantities of some cycloparaffins. Part II purification of the samples)
Authors: Kaarsemaker Sj. , Coops J. 
Published: September 2010

AbstractPurification of the cyclanes with 4 to 9 C‐atoms was effected by fractional distillation. Progress of the purification was checked with the aid of melting curves of the fractions (heat content vs. temperature curves of the melting process). The impurity content of the final samples is estimated at less than 0,2%. A fractionating column with a rotating cylinder and a small calorimeter for measurements on melting and transition processes at temperatures from — 180° to +70° are described.
Reactions of polypeptide esters in the solid state. I. Migration of methyl groups
Authors: Sluyterman L. A. Æ. , Veenendaal H. J. 
Published: September 2010

AbstractWhen tetraglycine methyl ester is heated at 100° C a decrease in methoxyl content is observed, mainly after an induction period of about 200 hours. The reaction is virtually finished after 600 hours. Previous powdering of the ester crystals slightly reduces the induction period. The reaction product mainly consists of a mixture of tetraglycine, N‐methyl‐glycyl‐triglycine (sarcosyl‐triglycine) and N‐dimethylglycyl‐triglycine.When alanyl‐triglycine methyl ester is heated at 100° C the induction period extends over several months.
Reaction products of primary β‐hydroxy‐amines with carbonyl compounds. I. The infrared absorption of acetals and ketals
Authors: Bergmann Ernst D. , Pinchas S. 
Published: September 2010

AbstractThe infrared absorption curves of 18 acetals and ketals have been measured in the region 1070–1190 cm−1.The C—O—C band at 1130 cm−1 (ethers) is split in the case of acetals and ketals (C‐O‐C‐O‐C) into three branches: at 1158—1190 cm−1 at 1124—1143 cm−1 and at 1063—1098 cm−1. The molecular extinction coefficient of the last band is 2—5.104. A fourth band appears in the region 1038—1056 cm−1.A tentative explanation of the observed effects is given.Another characteristic band, at 1110 cm−1 appears only in the spectra of acetals, not in those of ketals, and may be related to a C—H deformation, perturbed by a neighbouring O—C bond.
Reaction products of primary β‐hydroxy‐amines with carbonyl compounds. VI. Oxazolidines derived from N‐phenylethanolamine
Authors: Zimkin Emanuel , Bergmann Ernst D. 
Published: September 2010

AbstractN‐Phenylethanolamine condensed easily with aldehydes to give substituted oxazolidine. No reaction could be achieved with ketones.The molecular refraction and the infrared and ultraviolet spectra of the substances were measured. Critical evaluation of the results shows, that in these compounds the molecular refraction can only be used with great caution as a tool in determining the structure.The infrared spectra have been measured by Dr. S. Pinchas, the ultraviolet spectra by Dr. Y. Hirshberg, both of the Optics Department of this Institute.
Reactions of polypeptide esters in the solid state, II. A few cases of prevailing polycondensation. Remarks concerning the reaction mechanism
Authors: Sluyterman L. A. Æ. , Kooistra M. 
Published: September 2010

AbstractWhen tetraglycine methyl ester is heated at 185° C in the solid state or at 100° C dissolved in methanol, polymers containing small amounts of sarcosyl‐units are formed. An induction period occurs only under the first mentioned conditions. Also polymers obtained by heating triglycine methyl ester at 100°–100° C partly consisted of sarcosyl‐units. Some of the phenomena described in this and the preceding part1) are believed to be due to rigidity of the crystal lattice.
Hammett's substitution constant for the methylsulphonyl group and its mesomeric effect. (Properties of the sulphonyl group XXIII)
Authors: Kloosterziel H. , Backer H. J. 
Published: September 2010

AbstractHammett's substitution constant σ for the methylsulphonyl group has been determined, giving σ‐meta‐CH3SO2 = 0.615 (0.6522) and two values for σ‐para‐CH3SO2 viz. + 1.15 for the substituted phenol and aniline and + 0.73 for the benzoic acid. This indicates that the methylsulphonyl group has a negative mesomeric effect and that its sulphur atom can extend the octet of electrons to a decet structure.
Hydrolyse du 9,9‐bis‐Méthylthio‐Thioxanthène‐10‐Dioxyde. (Propriétés du groupe sulfonyle XXV)
Authors: Kloosterziel H. , Backer H. J. 
Published: September 2010

AbstractLe 9,9‐bis‐méthylthio‐thioxanthène‐10‐dioxyde (Ib), qui se forme par thiométhylation du thioxanthène‐10‐dioxyde (la), peut être regardé comme vinylogue des 1,1,1,1‐disulfuredisulfones.L'hydrolyse acide engendre le thioxanthone‐10‐dioxyde (IV) et diffère done essentiellement de celle que subit le bis‐méthylthio‐bis‐méthylsulfonylméthane (II). L'hydrolyse alcaline, qui décroche un groupe méthylthio, est analogue pour les deux composés. En outre, l'action de la potasse alcoolique sur Ib donne un produit dimère (III).L'oxydation au moyen d'acide perbenzoïque conduit à une trisulfone (Id), vinylogue des 1,1,1,1‐tétrasulfones inconnues.
Some remarks on the ionic radii of iron‐group elements. The influence of crystalline field
Authors: van Santen J. H. , van Wieringen J. S. 
Published: September 2010

AbstractThe ionic radii of iron group elements do not decrease monotonically from Ca towards Zn but show maxima at configurations d4, d5 and–possibly–d9, d10. An explanation is offered. It is based upon a heteropolar model where the influence of the other ions on the electronic distribution of 3d electrons is considered as a purely electrostatic influence of their net charges. The maxima are explained by the influence of a preponderantly cubic crystalline field, both for negliglible and strong interelectronic interaction.
Sodium salts of pectin and of carboxy methyl cellulose in aqueous sodium chloride. II Osmotic pressures
Authors: Pals D. T. F. , Hermans J. J. 
Published: September 2010

AbstractThe osmotic pressure of solutions of sodium pectinate and three samples of sodium carboxy methyl cellulose in aqueous solutions of sodium chloride were measured in a Fuoss and Mead osmometer. The primary aim was to obtain the molecular weights of the samples. As a by‐product the change of osmotic pressure with polymer concentration and salt content was studied.The reduced osmotic pressure proves to be a linear functon of the polymer concentration. The slopes of the lines p/c versus c vary with the concentration of the sodium chloride in a manner which is in reasonable agreement with the predictions of the Donnan equilibrium. An accurate check is impossible because the activity coefficients are not known.
Sodium salts of pectin and of carboxy methyl cellulose in aqueous sodium chloride. III. Potentiometric titration
Authors: Pals D. T. F. , Hermans J. J. 
Published: September 2010

AbstractThe changes in pH in the titration of carboxy methyl cellulose or pectin are much larger than those derived from the molecular dimensions on the basis of current theories. The possible causes of this discrepancy are discussed.
The behaviour of membranes between electrolyte solutions III: The dissociation of carboxyl groups in cellulose
Authors: Hirsch P. 
Published: September 2010

AbstractFormer work (I and II) led to the conclusion that the membrane diffusion potential at cellulose membranes must be connected with the degree of dissociation of acid groups in the membrane. In this communication the dissociation of carboxyl groups in cellulose is investigated with the aid of “neutralization curves”.Investigating cellulose material into which carboxyl groups had been introduced (oxycellulose), it appeared that the carboxyl groups occur in a reactive and an unreactive form, which are interconvertible. The unreactive carboxyl groups are assumed to be present in an anhydride form. If care is taken that the carboxyl groups are present in the reactive form, they can be titrated, and well‐defined neutralization curves can be obtained. Neutral salts greatly influence the titrations. Shape and position of the neutralization curves depend on the content of carboxyl groups in the material. — The law of mass action and the Donnan equilibrium as commonly formulated are not sufficient to explain shape and position of the neutralization curves, nor is it clear in what way they are connected with the membrane diffusion potentials.
Steric effects on mesomerism: VII. Deacylation of a number of acetylamino‐nitronaphthalenes and some of their derivatives
Authors: Krol L. H. , Verkade P. E. , Wepster B. M. 
Published: September 2010

AbstractThis paper contains data on the (pseudo) catalytic deacylation of 1‐ and 2‐acetylaminonaphthalene, five homonuclear acetylamino‐mononitronaphthalenes (including the 2,3‐isomer), five heteronuclear acetylaminomononitronaphthalenes, and some other acetylaminonaphthalene derivatives in an alkaline medium. The rates of deacylation are discussed in some detail, mainly on the basis of the peculiar electronic properties of the naphthalene nucleus, and from the point of view of the theory of steric effects on mesomerism.
Preparation et analyse thermogravimetrique des dithizonates d'argent, de plomb, de zinc et de cuivre
Authors: Pariaud Jean‐Charles , Archinard Pierre 
Published: September 2010

AbstractLa recherche de la solubilité des métaux dans l'eauJ. C. Pariaud et P. Archinard, Sur la solubilité des métaux dans l'eau. Bull, soc. chim. Mémoire no. 33 ( 1952 ) à paraitre.
nous a conduit à utiliser la dithizone comme réactif d'analyse. En liaison avec cette étude nous avons isolé et étudié le comportement à la chaleur des dithizonates d'Ag, de Pb, de Zn et de Cu.
Vanillic acid — a new reagent for thorium
Authors: Krishnamurty K. V. S. , Purushottam A. 
Published: September 2010

AbstractVanillic acid precipitates thorium quantitatively from solutions of pH 3.6 and about. The presence of a number of elements like calcium, strontium, barium, magnesium, zinc, cadmium, nickel, cobalt, beryllium, aluminium and the rare earths causes no interference. The precipitate on washing may be ignited and weighed as oxide. Thorium in monarite may be conveniently estimated in a single precipitation in this way.
Reactivity of 4‐nitropyridine‐N‐oxide (II)): Substitution of the nitro‐group by hydroxyl)
Authors: den Hertog H. J. , Combé W. P. 
Published: September 2010

AbstractWhereas 4‐nitropyridine‐N‐oxide is very stable towards dilute solutions of acids in water, its nitro‐group can be replaced by hydroxyl in a quick reaction by treating this substance with an alkaline solution of hydrogen peroxide in water at a temperature not surpassing 50°. This remarkable substitution reaction proceeds also when other 4‐substituted derivatives of pyridine‐N‐oxide and 4‐nitropyridine are reacted with the same reagent.
Kinetical experiments on ozonization reactions. III. The ozonization velocities of some benzene derivatives )
Authors: Wibaut J. P. , Sixma F. L. J. 
Published: September 2010

AbstractThe velocities of the reactions of ozone with a number of benzene derivatives were measured.The reactivity in various series of benzene derivatives proceeds as follows:magnified imageIsopropyl benzene reacts abnormally rapidly with ozone; it is probable that here, in addition to disruption of the benzene nucleus, other reactions take place; secondary butyl benzene does not show this different behaviour.Anisole reacts very rapidly with ozone so as to form a triozonide. The formation of a triozonide was also demonstrated with regard to o‐xylene and chlorobenzene.These results confirm the similarity in mechanism between the addition of ozone and the electrophilic substitution reactions, established on an earlier occasion Part I: H. Boer and F. L. J. Sixma, Rec. trav. chim. 70, 997 (1951); Part II: F. L. J. Sixma, H. Boer and J. P. Wibaut, Rec. trav. chim. 70, 1005 (1951).
.
The preparation of pyridine derivatives from halogenopyridines by means of the grignard reaction V. Application of the reaction to 3‐bromopyridine
Authors: Wibaut J. P. , van der Voort H. G. P. 
Published: September 2010

AbstractImproved directions are given for the preparation of an ethereal solution of 3‐pyridylmagnesium bromide. Starting from this compound, the following pyridine derivatives are prepared: 1‐(pyridyl‐3)‐heptene‐1, methyl‐(pyridyl‐3)‐ketone, (pyridyl‐3)‐methanal acetal, 3‐(pyridyl‐3)‐propene, and 3‐isobutenyl pyridine. By the oxidation of the latter substance, (pyridyl‐3)‐acetone is obtained.
Molecular complexes of iodine with olefinic compounds
Authors: Ketelaar J. A. A. , van De Stolpe C. 
Published: September 2010

AbstractFrom U.V. absorption spectra the equilibrium constants were determined for the formation of complexes of iodine with diisobutylene, (CH3)2C = CHC(CH3)3: Kx = 3.7; cis‐dichloroethane, Kx = 0.25; trichloroethene, Kx = 0.19 and tetrachloroethene, Kx = 0.11, as active components in n‐hexane as a solvent. The relation of the tendency towards association with the double bond character is stressed.
The reaction between urea and formaldehyde in concentrated solutions
Authors: de Jong J. I. , de Jonge J. 
Published: September 2010

AbstractThe nature and the velocities of the reactions occurring in concentrated solutions of urea and formaldehyde may be very similar to what is found in dilute systems.A rapid initial reaction between urea and formaldehyde, as reported in literature, was not observed and is shown to be due to the analytical methods used.
Photodecomposition of aqueous solutions of diazonium salts in the presence of mercurous ions
Authors: Bos J. G. , Alink R. J. H. , Dippel C. J. 
Published: September 2010

AbstractPhotodecomposition of aqueous solutions of o‐hydroxydiazonium salts leads todisproportionationof mercurous ions, in contrast to p‐amino‐benzenediazonium salts where mercury results fromreductionof mercurous ions by the photodecomposition products.
Studies in alums. II. Manganic and cobaltic alums
Authors: Zernike J. 
Published: September 2010

AbstractPreparation of Cs—Mn alum and mixed crystals of NH4—Mn—Al alum. Determination of their magnetic susceptibilities.Preparation of Rb—Co alum, its mixed crystals with Rb–Al alum, and mixed crystals of NH4—Co—Al and K—Co—Al alums. These are all diamagnetic.
Titration of adsorbed acids V
Authors: Mans A. E. , Vervelde G. J. 
Published: September 2010

AbstractThe effect of adding activated charcoal to solutions of relatively strong organic acids on the shape of the titration curves is examined theoretically. Titration curves were calculated on the basis of the assumption that the uneven distribution of the acids, due to the presence of the adsorbent, can be described as a two‐space distribution, one of the spaces containing the acids in the adsorbed state, the other containing the unadsorbed remainder of the acids and at the same time determining the potential of the hydrogen electrode. The ionic compositions of the solutions in both spaces are supposed to be interrelated in accordance with the rules of the Donnan distribution. The calculated curves show features quite similar to those obtained experimentally. Especially the remarkable influence of the valency of the base used for the titration could be explained satisfactorily.
The structure of the reaction product of ϵ‐caprolactam and phthalic anhydride
Authors: van der Want G. M. 
Published: September 2010

AbstractThe reaction product of ϵ‐caprolactam and phthalic anhydride is compared with that of ϵ‐aminocaproic acid and phthalic anhydride. The two are identical, and the structure can be designated as ϵ‐phtalimidocaproic acid.
Caractérisation des Amines au Moyen des Quinones Halogénées
Authors: Buu‐Hoï N. P. , Royer René , Eckert Bernard 
Published: September 2010

AbstractIl est montré que les quinones halogénées telles que la chloranile et surtout la 2,3‐dichloro‐1,4‐naphtoquinone peuvent être utilisées avantageusement pour caractériser les amines primaires et secondaires. De nombreuses aminoquinones nouvelles ont été préparées à cette fin, et certaines d'entre elles ont en outre un interét soit au point de vue biologique, soit au point de vue tinctorial.
Réaction du Chlorure Trichlorométhane‐Sulfénique sur les Mercaptannes
Authors: Backer H. J. , Westerhuis E. 
Published: September 2010

AbstractLe chlorure trichlorométhanesulfénique réagit aisément sur les thioalcools et thiophénols en produisant avec un bon rendement des esters trichlorométhanesulféniques (alcoyl‐ et aryl‐trichlorométhyl‐disulfures). Sauf quelques esters aromatiques cristallisés, ces produits sont des huiles lourdes.
Réaction du Chlorure Trichlorométhane‐Sulf́enique sur les Thioalcoolates et Thioph́enolates
Authors: Backer H. J. , Westerhuis E. 
Published: September 2010

AbstractLa réaction de CCl3SCl sur un mercaptide aliphatique donne naissance a un hexa‐alcoylthio‐diméthyldisulfure et à un dialcoyldisulfure simple.La réaction sur un thiophénolate produit, outre un disulfure, un hexa‐arylthio‐diméthyl‐tri‐sulfure. L'oxydation de ces derniers composés conduit à des esters de l'acide trithiopercarbonique.
The polarographic reduction of conjugated hydrocarbons. I. A theoretical discussion of the polarographic reduction of aromatic hydrocarbons
Authors: Hoijtink G. J. , van Schooten J. 
Published: September 2010

AbstractA theoretical discussion has been given of the linear relation between the half‐wave reduction potential ε1/2 of aromatic hydrocarbons and the root a of the zero order molecular orbital secular equation corresponding to the lowest non‐occupied π‐electronic level of the molecule, which can be represented by the formula:

The magnitude of the zero order “exchange” parameter γ = −2.25 ± 0.07 e.v. has been obtained by substituting the reduction potentials of some aromatic compounds in the given formula.The course of the reduction process can be qualitatively predicted by considering the π‐electronic distribution in the intermediate molecule ion and radical ion, the probability for the addition of the proton being largest at the carbon atom with the highest negative charge.
Spectrophotometric study of the solvation of iodine in dioxan solution II
Authors: Ketelaar J. A. A. , van de Stolpe C. , Goudsmit A. , Dzcubas W. 
Published: September 2010

AbstractThe solvation of iodine in dioxan‐carbon tetrachloride and dioxan‐n‐hexane solutions was studied by measuring the absorption spectra at different concentrations and temperatures. The concentration of the iodine‐dioxan complex is derived both from the extinction at about 4525 Å and at 2650 Å. The equilibrium constants thus derived from two independent series of measurements were found to correspond within the limits of accuracy, thus proving that both the absorption in the visible and in the ultraviolet part has to be ascribed to the same iodine‐dioxan complex 1:1.The equilibrium constant Kx at 25° C was found to be 9.1 and 9.3 for carbon tetrachloride and n‐hexane solutions respectively. From the dependance on temperature the heat of formation was found to be 3300 ± 200 cal/mole and 3500° 200 cal/mole respectively.