bluuebunny/crossref_metadata_2025_split huggingface dataset:
Total synthesis in the steroid series. II: d,l −3‐ethylenedioxy‐11 β‐hydroxy‐17‐oxymethyl‐D‐homoandrosta‐5: 16‐diene 18‐acid lactone (18 → 11), an intermediate to aldosterone
Authors: Szpilfogel S. A. , van der Burg W. J. , Siegmann C. M. , van Dorp D. A. 
Published: September 2010

AbstractAttempts to transform potential intermediates prepared earlier into 18‐oxygenated steroids are described. One of the routes lead to the substiuted D‐homoandrostane derivative (XXIX) mentioned in the title.
Investigations on herbicides I. 2‐(Substituted amino)‐4,6‐dichloro‐1,3,5‐triazines
Authors: Koopman H. , Daams J. 
Published: September 2010

AbstractIn view of their herbicidal properties a number of 2‐(substituted amino) −4,6‐dichloro‐1,3,5‐triazines was synthesized by a method described in the literature. The influence of the side chain on the herbicidal properties was determined. For this reason some derivatives mentioned in the literature were included to compare them with the new compounds in our biological tests.
Synthesis of β‐phenylethylamine derivatives V: Bronchodilators II
Authors: Moed H. D. , van Dijk J. , Niewind H. 
Published: September 2010

AbstractThe chemistry is described of three adrenaline‐like compounds: magnified imageThe compounds were examined for their ability to protect guinea pigs from bronchial spasm induced by acetylcholine. The possible influence of the hydroxylated benzene nucleus of the side chain on the drug‐receptor combination is discussed.
Foam stability: Part IV. Kinetics and activation energy of film rupture
Authors: de Vries A. J. 
Published: September 2010

AbstractHigh‐speed cinematography of collapsing lamellae of an aqueous Tee‐pol solution reveals that spontaneous rupture always takes place in the thinnest part of the lamella. The rate of hole expansion is dependent on the thickness of the lamella; its value is found to be in the order of some hundreds of cms per second. Dupré's assumption that the released surface energy will be completely converted into kinetic energy of the liquid appears to be essentially correct. Film rupture in a foamed aqueous solution of ammonium oleate is shown to proceed at a rate which is at least of the same order of magnitude as that in the isolated lamellae.Deformation of a foam lamella occurs locally when a hole is about to be formed. The deformation and the very first beginning of hole expansion require an energy of activation which is calculated with the aid of a geometrical model. The energy is more than 1,000 kT units in a “black” film of an aqueous soap solution. This amount of energy has to be supplied in order to increase the interfacial area. The activation energy is proportional to the square of the film thickness and its value is hardly influenced by the magnitude of the electric double‐layer interaction.The formation and relative stability of “black spots” in films of much larger thickness than the spot itself is shown to be the result of an equilibrium, existing at a thickness between 100 and 150 Å, of the three forces coming into play: London‐Van der Waals attraction, double‐layer repulsion and surface tension.
Electrochemical researches on paraffin membranes III. Measurements of the activity of the calcium ions in solutions of gelatin and gum arabic
Authors: Tendeloo H. J. C. , Krips A. 
Published: September 2010

AbstractA membrane consisting of a mixture of pure paraffin, calcium oxalate and a non‐ionogenic detergent can be used as an electrode to determine pCa in solutions of gelatin and gum arabic.
The effect of U.V.‐light on some components of the nucleic acids: I. Uracil, thymine
Authors: Rörsch A. , Beukers R. , Ijlstra J. , Berends W. 
Published: September 2010

Abstract
At least three different reactions occur on irradiation of uracil in aqueous solution with light from a low pressure mercury lamp. One of these is reversible. The most rapid irreversible reaction may be a cause of the mutagenic and lethal effect of this light. The slow irreversible reaction, which also occurs in the irradiation of thymine, is probably brought about by the peroxide, which is produced to a small extent.
When they are dissolved in water many compounds have an absorption maximum in the neighbourhood of 200 mμ.
Oxidation of cholesterol. Influence of the stereochemical configuration of halogenated cholestane derivatives on the yield of 17‐ketosteroids
Authors: Maas S. P. J. , de Heus J. G. 
Published: September 2010

AbstractSeveral halogenated and hydrohalogenated cholesteryl acetates were subjected to comparative oxidations with chromic acid. In addition 5α‐cholestan‐3β‐yl acetate, 5β‐cholestan‐3β‐yl acetate and 3β,5α,6β‐trihalogenated cholestane were used as a starting material. Comparison of the results of the experiments showed that the bromine atom in the β‐position at C6 exerted the greatest‐influence on the formation of 17‐ketosteroids.
The chemical effect of light on sodium ρ‐methoxybenzenediazosulphonate
Authors: Dijkstra R. , de Jonge J. 
Published: September 2010

AbstractIt could be derived from kinetic measurements that irradiation of an aqueous solution of ρ‐methoxybenzenediazosulphonate with ultra‐violet light causes a dissociation of the sulphonate ion to form a ρ‐methoxybenzene‐diazonium ion and a sulphite ion. The ions produced photochemically slowly recombine in the dark to form back the original sulphonate ion.The reactions may be represented by the scheme: magnified imageThe occurence of a labile or cis‐diazosulphonate can practically be precluded.
Implications of template theories of protein biosynthesis
Authors: Dalgliesh C. E. 
Published: September 2010

AbstractThe organization, during biosynthesis, of the specific structures of proteins can reasonably be explained on the basis of the ability of macromolecules (provided they are formed from more than a few distinguishable monomeric forms) to carry information. In such “template mechanisms” the template may function by determining either a sequence of reactions in time, or a sequence of reactions in space. In the latter case a template might be a “positive” or a “negative” of the protein being formed. A “negative” relationship is usually assumed, with nucleic acid playing the complementary role. Even if a template determines primarily a sequence of reactions in space, rather than in time, the individual reactions (i.e. formation of individual peptide bonds) probably occur successively rather than simultaneously. Possible “template mechanisms” for protein synthesis are outlined in general terms, and some simple kinetic consequences are considered. Other problems discussed include the desirability of assessing the contribution of exchange (if it occurs) in the incorporation of amino acids into proteins, and the implications of a template mechanism for incorporation of intact peptides.
Electrochemical researches on paraffin membranes IV. Measurements of the binding of calcium ions by human serum albumin
Authors: Tendeloo H. J. C. , Krips A. 
Published: September 2010

AbstractTo test the usefulness of a paraffin membrane containing calcium oxalate as an electrode for the determination of concentrations of calcium ions the binding of these ions by human serum albumin has been investigated. It has been found that 0.13 ± 0.02 milligram atoms of calcium ions are bound by one gram of human serum albumin.
Equilibria in the ternary system sodium metaborate ‐ sodium perborate ‐ water
Authors: van Gelder D. W. 
Published: September 2010

AbstractThe equilibria between the solid and liquid phases in the system sodium metaborate–sodium perborate–water have been investigated at 18°, 25°, 37.5° and 50° C. Three stable solid phases were found: NaBO2.4H2O, NaBO3.3H2O and NaBO2.NaBO3.4H2O. Metastable equilibria with NaBO3.4H2O as the solid phase could be realised for a long time over the whole region.
Self‐cooling in solid reactions. A.‐ dehydration of alums
Authors: Anous M. M. T. 
Published: September 2010

AbstractSingle crystals of potash alum of different weights were grown on copper‐constantan thermocouple junctions. The self‐cooling was determined during dehydration. Very small increase in self‐cooling with increase in weight was noticed above ∼3 g. The self‐cooling was also determined for chrome alum crystals of mass ∼ 1 g during dehydration at thermostat temperatures of 19.5 to 39.5°. The rate of propagation previously determinedAnous, Bradley and Colvin, J. Chem. Soc. 1951, 739, 3348.
), as well as the actual crystal temperature measured in this work, were used to calculate the activation energy. It is ∼ 26 kcal per mole which is in very good agreement with that obtained by using the theoretically calculated self‐cooling.
Corrections of the theory of the flat diffuse double layer
Authors: Sparnaay M. J. 
Published: September 2010

AbstractThe potential distribution in the diffuse part of the ionic double layer, which is formed at the interface between a solid and an electrolyte solution, is given by the Poisson Boltzmann equation. This equation, involving some approximations, is modified such, that now the following effects are included:
The effect of ionic sires.
The effect of the dependence of the dielectric constant upon the ionic concentration and upon the electric field, present near the interface. Two opposed tendencies can be distinguished here: a) the solution near the interface is polarized [Prigogine, Mazur and Defay) usually giving rise to a decrease of the ionic concentration near the interface; b) Coulomb interactions near the interface, between the ions and the interface, are different from those, predicted from the unmodified theory. This will give rise to a relative increase of the ionic concentration. It appears, that tendency b) outweighs tendency a).A flat interface and a 1‐1 electrolyte solution are considered only. The effects are represented as correction terms added to the original Poisson Boltzmann equation. The new equation is integrated using elementary methods. The result of the calculations is, that corrections are negligibly small, when the electrolyte concentration is of the order of 10−3 normal. When the concentration is 10−2 normal, the corrections amount to 10‐20% of the value of the double layer potential, whereas the given treatment breaks down, when the concentrations are 10−1 normal or higher.
Selective reduction by calcium hexammine II. Reductive cleavage of sulphur compounds
Authors: van Schooten J. , Knotnerus J. , Boer H. , Duinker Ph. M. 
Published: September 2010

AbstractCalcium hexammine suspensions as developed in earlier work for reduction of aromaticsH. Boer and Ph. M. Duinker, Rec. trav. chim. 77, 346 (1958).
have now been found to constitute mild and convenient agents for effecting reductive cleavage of aromatic types of sulphur compounds, in which the sulphur atom is linked either directly to the aromatic nucleus or to a methylene group which is attached to an aromatic nucleus.This reduction process is always accompanied by the cleavage of a carbon‐sulphur bond, the sulphur compound being split into lower molecular weight products, unless the sulphur was bound in a ring. Alkyl benzyl sulphides are split into a mercaptan and toluene and alkyl phenyl sulphides into a thiophenol and an alkane, while benzothiophenes quantitatively yield 2‐alkylthiophenols and dibenzothiophene yields about 80 mol% 2‐cyclohex (en) ylthiophenol.Sulphur linked to two CH2‐groups, each adjacent to an aromatic nucleus, is removed as H2S.The relations between the structures of the sulphur compounds and those of their reduction products are discussed with respect to possible reaction mechanisms.
The preparation of some dialkyl p‐nitrophenyl phosphates
Authors: de Roos A. M. , Toet H. J. 
Published: September 2010

AbstractDialkyl p‐nitrophenyl phosphates have been prepared by the interaction of dialkyl phosphorochloridates and sodium p‐nitrophenoxide. Physical constants of these faintly yellow coloured phosphates are recorded, infrared spectra included.
Chemistry of acetylenic ethers XXXIV: On the reactivity of acetylenic ethers and thioethers; the dual character of alkylthio groups
Authors: Volger H. C. , Arens J. F. 
Published: September 2010

AbstractIn this paper we compare addition reactions to ethoxyethyne with those to ethylthioethyne, in order to show up similarities and differences with respect to the orientations. The similarities are due to the similarity in character of OR and SR groups. Both groups allow the following polarisation: magnified imageElectrophilic reagents are therefore added to the β‐carbon atom. The differences, on the other hand, concern additions of nucleophilic reagents BH. Ethoxyethyne, polarised as above, yields adducts of the type: magnified imageEthylthioethyne, however, is converted into products of the type:
equation image
This important difference is explained by the ability of sulphur to accomodate a decet of electrons in its valence shell. It can therefore also act as an electron acceptor, allowing reversed polarisation of ethylthioethyne thus: magnified imageThis is especially favourable for reactions with nucleophilic reagents and results in the observed mode of addition.Differences between the effects of alkoxy and alkylthio groups encountered in the literature can be understood from this dual nature of alkylthio groups.
Investigations on pyrazine derivatives IV. The preparation and specific oxidation of a number of 2,3‐dialkoxy‐ and 2,3‐diaryloxy‐quinoxalines
Authors: Mager H. I. X. , Berends W. 
Published: September 2010

AbstractThe preparation of a number of 2,3‐dialkoxy‐ and 2,3‐diaryloxyquinoxalines is described in detail. Unlike many other substituted quinoxaline derivatives, these compounds appear to be relatively very stable towards potassium permanganate.It is demonstrated that the introduction of particular substituents into the benzene ring of these quinoxaline derivatives again produces starting materials for the preparation of pyrazine carboxylic acids.
The preparation of some iso‐propyl p‐nitrophenyl alkylphosphonates
Authors: de Roos A. M. , Toet H. J. 
Published: September 2010

AbstractIn the series of the iso‐propyl p‐nitrophenyl alkylphosphonates the lower homologues have been prepared by interaction of iso‐propyl alkylphosphonochloridates and sodium p‐nitrophenoxide. All these p‐nitrophenyl derivatives are yellow liquids; boiling points and refractive indices are given, as well as an example of the infrared spectra.
Isotherms for preferential adsorption from binary liquid mixtures, based on langmuir equations
Authors: Klinkenberg A. 
Published: September 2010

AbstractThe isotherms for preferential adsorption from a binary liquid mixture may be of so‐called “U” or “S” shape. Those of “U” shape are in certain cases describable by Langmuir‐type equations in terms of two parameters. These are the relative adsorbability of the two components and the volume of the adsorbed layer, the latter being considerably smaller than the volume of the pores within the particles of the adsorbent. It is shown, how these parameters may be derived from experimental data.
Cupric tetramminosulphate. I. Thermal decomposition
Authors: Anous M. M. T. 
Published: September 2010

AbstractA completely anhydrous sample of cupric tetramminesulphate has been prepared. The product previously reported to be anhydrous was found to contain up to 4% of moisture on keeping over calcium chloride. Thermal decomposition of the slightly hydrated, as well as the completely anhydrous compounds, was followed in a closed apparatus at atmospheric pressure and/or in a vacuum. Two molecules of ammonia were reversibly liberated on two successive steps. In a vacuum, the completely anhydrous, deep violetblue Cu(NH3)4SO4 lost one ammonia molecule at 30° and a second molecule at 55°, giving the pale blue Cu(NH3)2SO4. At temperatures above ∼90°, irreversible decomposition of the diammine occurs with the gradual formation of a dark‐grey to brown product, accompanied by sublimation of ammonium sulphate.
Investigations on pyrazine derivatives. V. A more detailed investigation on the catalytic hydrogenation of esters of pyrazine carboxylic acids
Authors: Mager H. I. X. , Berends W. 
Published: September 2010

AbstractIn the first publication in this series it was shown that only partial reduction of the pyrazine ring occurs in the catalytic hydrogenation of tetra‐carbethoxypyrazine. The remaining double bonds in the resultant reaction product are apparently stabilised. In agreement with the hypotheses put forward to explain this result, esters of other pyrazine carboxylic acids also are only partially reducible with palladium on carbon at room temperatures. The conclusion must be drawn that a carbalkoxy group attached to a pyrazine ring protects an adjacent double bond in the ring against catalytic hydrogenation.The partially hydrogenated products from the esters of some pyrazine carboxylic acids are extraordinarily labile. Dehydrogenation by dismutation or reoxidation, which occurs to some extent, can be followed from the spectra.Similar phenomena have been encountered in the pyridine series, which may be put forward as supporting the conclusions reached.
Lyotropic numbers of the formate and acetate ions and related thermodynamic properties
Authors: Morris D. F. C. 
Published: September 2010

AbstractThe data of Buchner and Kleijn on the flocculation of agar have been employed to calculate the lyotropic numbers of the formate and acetate ions. Hydration heats of the ions, comparable to those of Latimer, Pitzer and Slansky, have been derived from the lyotropic numbers. Other magnitudes, which have been obtained, include lattice energies and standard enthalpies of formation of formates and acetates.Estimates of the standard enthalpies of formation of the formate and acetate radicals are quoted, and values for the electron affinities of the radicals are given.
Electrochemical researches on paraffin membranes V. Antagonism of uni‐ and higher valenced cations
Authors: Tendeloo H. J. C. , Krips A. 
Published: September 2010

AbstractMeasurements are described on the e.m.f. of cells with electrodes of paraffin and polystyrene membranes of different composition in a number of solutions containing uni‐ or higher valenced cations. From these researches it follows that uni‐ and higher valenced cations behave antagonistically.
Theoretical study of nitrogen heterocyclics. IV. Molecular diagrams and carcinogenic activity of some naphthindoles
Authors: Fernandez‐Alonso J. I. , Domingo Rosario , Vila L. Carbonell 
Published: September 2010

AbstractMolecular‐orbital calculations of structural static parameters (bond orders, π‐electron densities and free valences) and dynamic indices (atom, ortho‐ and para‐localization energies) are presented for a number of naphthindoles. The results are used to predict the chemical properties of the molecules. We have made a comparison of the carcinogenic inactivity and the static and dynamic complex indices used to characterize the K region in some benzindoles and these naphthindoles.
The preparation of some p‐nitrophenyl dialkylphosphinates
Authors: de Roos A. M. , Toet H. J. 
Published: September 2010

AbstractThe lower homologues in the series of the p‐nitrophenyl dialkylphosphinates have been prepared by the interaction of dialkylphosphinic chlorides and p‐nitrophenol in the presence of triethylamine. Physico‐chemical constants of the yellow phosphinates are recorded; an example of the infrared spectra is given.
Analytical applications of a celite/dinitrophenylhydrazine column
Authors: Begemann P. Haverkamp , de Jong K. 
Published: September 2010

AbstractA method is described for the conversion of carbonyl compounds, which are present in very small concentrations in a light petroleum solution, into their 2,4‐dinitrophenylhydrazones. The light petroleum solution is passed through a column in which Celite acts as a carrier for 2,4‐dinitrophenyl‐ hydrazine hydrochloride. The carbonyl compounds then become almost quantitatively bound as 2,4‐dinitrophenylhydrazone.This same column can also be used for the decomposition of ozonized, unsaturated compounds, with the simultaneous formation of the dinitrophenylhydrazones of carbonyl fragments, so enabling the location of double bonds in minute amounts of material.
Reaction products of primary β‐hydroxyamines with carbonyl compounds: XV. Condensation of Carbonyl Compounds with 3‐Mercaptopropylamine
Authors: Bergmann Ernst D. , Kaluszyner A. 
Published: September 2010

Abstract3‐Mercaptopropylamine gives with formaldehyde and cyclohexanone tetrahydro‐1,3‐thiazines, whilst with benzaldehyde largely the corresponding Schiff base is obtained.Some observations on the synthesis of 3‐mercaptopropylamine are recorded.
Reaction products of primary β‐hydroxyamines with carbonyl compounds: XVI) Condensation of Carbonyl Compounds with 4‐Hydroxy‐ and 4‐ Mercaptobutylamine
Authors: Bergmann Ernst D. , Kaluszyner A. 
Published: September 2010

AbstractThe condensation of 4‐hydroxybutylamine with various carbonyl compounds gave a cyclic compound (hexahydro‐1,3‐oxazepine) only in the case of formaldehyde. Benzaldehyde and acetophenone yielded the corresponding Schiff bases, cyclohexanone a mixture of the Schiff base with the isomeric cyclic compound. 4‐Mercaptobutylamine gave with cyclohexanone only the (cyclic) hexahydro‐1,3‐thiazepine.Easy methods for the preparation of the two substituted amines are described.
Reaction products of primary β‐hydroxyamines with carbonyl compounds: XVII) Condensation of Carbonyl Compounds with Tetramethyleneglycol
Authors: Bergmann Ernst D. , Kaluszyner A. 
Published: September 2010

AbstractThe behaviour of tetramethyleneglycol towards aldehydes and ketones has been compared with that of ethyleneglycol and trimethyleneglycol. There is a certain disinclination to form the seven‐membered 1,3‐dioxepane ring. In several instances, open‐chain acetals have been obtained; many ketones did not react at all or only under relatively stringent conditions.The infrared spectra of the condensation products have been determined and compared with those of the 1,3‐dioxolanes and 1,3‐dioxanes.
Orthothioesters and 1,1‐bis‐(ethylthio)‐1‐alkenes (thioacetals of ketenes)
Authors: Rinzema L. C. , Stoffelsma J. , Arens J. F. 
Published: September 2010

AbstractA number of ethyl orthothioesters has been prepared by refluxing acid chlorides with ethanethiol and zinc chloride. The substances very easily lose one mole of ethanethiol by distillation in the presence of traces of acids, affording the thioacetals of substituted ketenes VII. The structure of the latter compounds follows from the hydrolysis of their sulphones VIII into the next lower aldehydes IX and bis (ethanesulphonyl) methane X.It is pointed out, that interesting reactions can be carried out by making use of various methods for the introduction and elimination of thioether groups (see reaction schemes on pages 5 and 6).
Untersuchungen über Homologe Verbindungen von Isodehydracetsäure und deren Ester
Authors: Salemink C. A. 
Published: September 2010

AbstractDie vorliegende Arbeit beschäftigt sich mit der Darstellung von bisher nicht beschriebenen höheren Homologen der Isodehydracetsäure und deren Ester. Diese Verbindungen zeigen antibakterielle Wirkungen bei verschiedenen Bakterienarten.
Derivatives of amino‐acids and peptides IV: The synthesis of peptides by means of ethoxyethyne
Authors: Panneman H. J. , Marx A. F. , Arens J. F. 
Published: September 2010

AbstractDipeptides are obtained optically pure and in good yield by boiling equivalent amounts of N‐acylamino‐acids and amino‐ester hydrochlorides with ethoxyethyne in ethyl acetate containing 0.5% of water.For the preparation of higher peptides it is preferable to add the amino‐component not as hydrochloride but as free ester, because otherwise partial racemisation may occur.By means of this method the hexapeptide, pro‐val‐lys‐val‐tyr‐pro, a sequence present in β‐corticotropin, has been prepared.