bluuebunny/crossref_metadata_2025_split huggingface dataset:
The ozonisation and the ozonolysis of furan and of some methylated furans in connection with the reactivities of the bonds in the ringsystem
Authors: Jibben B. P. , Wibaut J. P. 
Published: September 2010

AbstractThe ozonisation and ozonolysis of the following compounds have been investigated: furan, 2‐methylfuran, 2,3‐, 2,4‐ and 2,5‐dimethylfuran and 2,3,5‐trimethylfuran. When dissolved in chloroform, these compounds take up about 1.6 mol of ozone per mol of furan derivative at –60°, and resinification is practically absent under these conditions. On decomposition of the resultant ozonides under a variety of conditions, dicarbonyl compounds are produced and they have been determined both qualitatively and quantitatively. Glyoxal, which may be produced from either the two β‐C atoms or one α‐ and one β‐C atom of the furan nucleus, is the sole dicarbonyl compound produced in the ozonolysis of furan. The same holds,mutatis mutandis, for the ozonolysis of 2,4‐dimethylfuran, where methylglyoxal is the sole dicarbonyl compound produced. In the ozonolysis of the remaining furan derivatives along with dicarbonyl compounds produced from the two β‐C atoms in the furan nucleus, there are produced also those derived from an α‐ and a β‐C atom of the furan nucleus. Thus, for example, in the ozonolysis of 2,3‐dimethylfuran, glyoxal and dimethylglyoxal are produced as well as methylglyoxal. Besides dicarbonyl compounds, considerable amounts of formic and acetic acids are also produced in the decomposition of the ozonides and these have been determined approximately.The experimental results may be explained by assuming that two different reactions occur in the interaction of ozone and the furan derivatives examined. In the first reaction two molecules of ozone are taken up on the two α‐β‐bonds of the furan nucleus. On decomposition of the diozonide obtained there is produced a dicarbonyl compound containing the two β‐C atoms of the furan nucleus. In the second reaction only one molecule of ozone is absorbed. The mono‐ozonide on decomposition produces two dicarbonyl compounds, which contain one α‐ and one β‐C atom of the furan nucleus. During the decomposition of the ozonides hydroperoxides derived from the dicarbonyl compounds are produced as by‐products. The hydroperoxides partly decompose by peroxide transformation into carboxylic acids.A reaction mechanism put forward byBailey and Colombto explain the occurrence of dicarbonyl compounds containing an α‐ and a β‐C atom from the furan nucleus, must be rejected for the furan derivatives we have studied on the fact that the take up of ozone was found to be 1.6 mol per mol of furan derivative.
The liquid‐junction potentials between some buffer solutions in methanol and methanol‐water mixtures and a saturated KCl solution in water at 25°
Authors: de Ligny C. L. , Rehbach M. 
Published: September 2010

AbstractThe determination of the liquid‐junction potential at the interface of an oxalate and a succinate buffer solution of known pH* in water, methanol or a methanol‐water mixture and a saturated KCl solution in water at 25° is described. When the pH* of such a solution is measured by means of a pH meter standardized by an aqueous standard solution, this liquid‐junction potential causes an error of over 2 pH* when the methanol content of the solution is high.
Investigations on sterols XV: The syntheses and properties of 9β,10α‐progesterone and 6‐dehydro‐9β,10α‐progesterone
Authors: Westerhof P. , Reerink E. H. 
Published: September 2010

AbstractA description is given of the syntheses of 9β,10α‐progesterone and 6‐dehydro‐9β,10α‐progesterone using lumisterol2as the starting material.
Ultraviolet absorption spectra of some sterically hindered p,p′‐dimethoxystilbenes
Authors: Laarhoven W. H. , Nivard R. J. F. , Havinga E. 
Published: September 2010

AbstractThe ultraviolet absorption spectra of a series of methyl‐ and ethyl‐substituted p,p′‐dimethoxystilbenes were measured. The spectra could be described by assuming the presence of four overlapping absorption bands. Three of these bands, the positions of which (∼ 207, 230 and 285 mμ) are hardly affected by alkyl substitution, are tentatively interpreted as “benzene bands”; 4,4′‐dimethoxydibenzyl is found to show comparable absorptions. The fourth band (at 307 mμ in the case of unsubstituted 4,4′‐dimethoxystilbene) is assumed to correspond to an N → V transition in the stilbene chromophore. With the substituted dimethoxystilbenes the oscillator strength of this band decreases in the following sequence: α‐methyl‐ ; 2,2′‐dimethyl‐ ; 2,2′‐diethyl‐ ; α,2′‐dimethyl‐ ; α,2‐dimethyl‐ ; 2,2′,6,6′‐tetramethyl‐ ; α,α′‐dimethyl‐ ; α,2,2′‐trimethyl‐ ; α,α′‐diethyl‐ ; α,α′,2‐trimethyl‐ and α,α′,2,2′‐tetramethyl‐4,4′‐dimethoxystilbene.There is an increasing hypsochromic shift that in general runs parallel to the decrease in extinction coefficient, λmax gradually falling from 307 mμ to ∼ 230 mμ.The angles of twist (ψ) of the phenyl nuclei are estimated from the oscillator strengths of the long‐wavelength stilbene absorption bands. The values obtained show qualitative agreement with the results of calculations by the molecular orbital method as performed by Suzuki and by Riezebos.
Chemistry of acetylenic ethers XLVI: Addition of thiols to acetylenic ethers
Authors: Alkema H. J. , Arens J. F. 
Published: September 2010

AbstractThe free‐radical addition of ethanethiol to ethoxyethyne produces muchcisand a littletrans1‐ethoxy‐2‐(ethylthio)ethene, whereas the nucleophilic addition of sodium ethanethiolate yields 1‐ethoxy‐1‐(ethylthio)ethene.The same applies to additions of other thiols.
Spectrophotometric investigations of the mechanism of complex formation: Part III. Complexes of aluminium chloride with bis‐(cyclopentadienyl)‐titanium dichloride
Authors: Adema E. H. , Bos H. , Vrinssen C. H. 
Published: September 2010

AbstractSpectrophotometric titration curves of aluminium chloride with bis‐(cyclopentadienyl)‐titanium dichloride reveal the formation of two complexes: (C5H5)2TiCl2. (AlCl3)2and (C5H5)2TiCl2. (AlCl3)5. The spectra of these complexes are shown.
The influence of non planarity in styrene and stilbene derivatives III: Syntheses and ultra‐violet spectra of 4‐4′‐substituted cis‐ and transstilbenes
Authors: Riezebos G. , Havinga E. 
Published: September 2010

AbstractA series of cis‐ and trans‐stilbenes magnified image, in which R = H, CN, NO2 and R′ = H, CH3, OCH3, have been synthesized and their ultra‐violet absorption spectra have been recorded. The differences between the spectra of the trans‐compounds and the sterically hindered cis‐isomers as well as the influence of the substituents on the spectra are discussed by means of a semiquantitative treatment.
Synthesis of enantiomeric mixed‐acid phosphatides
Authors: de Haas G. H. , van Deenen L. L. M. 
Published: September 2010

AbstractThe synthesis is described of two optically pure L‐α‐lecithins and of one D‐α‐lecithin, each containing one saturated and one unsaturated fatty acid, and of two enantiomeric α‐lecithins composed of two saturated fatty acids of unequal chain length. A modification of the procedure allowed the preparation of two structurally isomeric mixed‐acid L‐α‐phosphatidyl‐ethanolamines. The suitability of the synthetic phosphatides as substrates for biochemical model studies is demonstrated by experiments with snake‐venom phosphatidase.
The system iridium ‐ oxygen: II The dissociation pressure of IrO2
Authors: Cordfunke E. H. P. , Meyer G. 
Published: September 2010

AbstractThe dissociation pressure of IrO2 has been investigated. The results can be explained by the formation of a non‐stoichiometric oxide. This has been confirmed by X‐ray analysis. The composition of the IrO2‐x‐phase (in equilibrium with iridium) has been determined as a function of the temperature.The oxygen pressure of the three‐phase equilibrium (IrO2‐x‐Ir‐G) can be represented by the equation:

For stoichiometric IrO2 from our measurements, it follows that:ΔH298.16°K=−65.5(±1.5)kcal/mole.
Some characteristics of the hydration of 3CaO.Al2O3 in the presence of CaSO4.2 H2O
Authors: Stein H. N. 
Published: September 2010

AbstractExperiments on the hydration of 3CaO.Al2O3 in a solution of Ca(OH)2 in the presence of CaSO4.2H2O are described. An approximate theoretical treatment of the retarded stage of this reaction is offered on the basis of water transport through a calcium hydrosulphatoaluminate (ettringite) layer on the 3CaO.Al2O3 particles as the rate‐determining step of the reaction. The water transport may be effected either by diffusion or by Poiseuille flow. The most plausible explanation of the experimental results is that the deposition of ettringite on the surface layer continues during the retarded stage, and that the surface layer expands at its outside more rapidly than the particles themselves shrink in the course of the reaction.
An improved synthesis of a mixed acid l‐α‐phosphatidylethanolamine, containing a polyunsaturated fatty acid
Authors: Daemen F. J. M. , de Haas G. H. , van Deenen L. L. M. 
Published: September 2010

AbstractA method is described for the preparation of silver benzylN‐t‐butyloxycarbonyl‐2‐aminoethyl phosphate. A reaction between this substance and γ‐palmitoyl‐β‐linoleoylglycerol‐L‐α‐iodohydrin, after removal of the protecting groups, furnished γ‐palmitoyl‐β‐linoleoyl‐L‐α‐phosphatidylethanolamine in high yield.
Aromatic sulphonation VI: A kinetic study on the sulphonation and dealkylation oft‐butylbenzene in concentrated aqueous sulphuric acid
Authors: Cerfontain H. , Kaandorp A. W. , Sixma F. L. J. 
Published: September 2010

Abstractt‐Butylbenzene has been sulphonated homogeneously in aqueous sulphuric acid solutions varying from 72.4 to 91.0 wt‐% at 5.0°, 25.0° and 35.0°. Under these conditions dealkylation oft‐butylbenzene occurs. Pseudo first order rate constants for the sulphonation and the dealkylation reaction have been determined.The overall rate constant for sulphonation oft‐butylbenzene is smaller than that of toluene. It is suggested that this difference arises predominantly from increased steric hindrance fororthosubstitution in the former case.The overall rate constant for dealkylation increases rapidly with increasing acid concentration: at 25° d(logkexp)/d (.‐HR) = 1.08, whereas d(logkexp)/d (‐H0) ∼ 2.0. The apparent activation energy for the dealkylation reaction decreases from 34.0 kcal · mole−1in 77.5 wt‐% sulphuric acid to 19.5 kcal · mole−1in 85.8 wt‐% sulphuric acid. Possible mechanisms for the dealkylation reaction are proposed and it is suggested that the C1ring protonation oft‐butylbenzene is governed by theHRacidity function.
Investigations on organotin compounds: Part XVIII. The basicity of triorganotin hydroxides
Authors: Janssen M. J. , Luijten J. G. A. 
Published: September 2010

AbstractThe basicities of a number of triorganotin hydroxides have been compared by measuring the acid dissociation constants of aquotriorganotin cations in 44% aqueous ethanol (by weight) at 25°. The equilibrium constants are given in concentration constants Kc, valid at an ionic strength of 0.01. Two series of organotin compounds were studied, namely trialkyltin hydroxides and mixed ethylphenyl derivatives. Basicities are influenced by inductive effects but also strongly by steric effects. Whether also an influence of d π ‐ p π overlap exists in the phenyltin series, cannot be clearly distinguished, because much if not all of the pK shift on introduction of phenyl groups can be explained in terms of inductive and steric effects.
Studies in IVth group organometallic chemistry: XII. Linear poly‐addition polymers derived fromp‐phenylene‐bis‐(dimethyltin hydride) and diphenyltin dihydride
Authors: Leusink A. J. , Noltes J. G. , Budding H. A. , van der Kerk G. J. M. 
Published: September 2010

AbstractThe preparation and characterization of linear organometallic polymers containing tin or tin and lead in the polymer main chain is described. These polymers have been obtained by poly‐addition reactions fromp‐phenylene‐bis‐(dimethyltin hydride) and various di‐olefinic, acetylenic and di‐acetylenic compounds. Reactions of this novel organotin hydride have also been carried out withp‐styrenyl derivatives of germanium, tin and lead, leading to monomeric compounds containing four hydrocarbon‐linked metal atoms.Furthermore, linear polyesters and polyamides containing organotin radicals in the polymer backbone have been prepared from diphenyltin dihydride and difunctionally‐unsaturated esters and amides.
The separating performance of fractionating columns
Authors: Haring H. G. , Knol H. W. 
Published: September 2010

AbstractThe definitions of theoretical plate and separating power are discussed, and the concept of “plate equivalency”, now called the “separating performance” of a fractionating column, is worked out.The separating performance is a dimensionless measure for the actual separation (the separating effect) obtained under conditions of partial reflux, as a counterpart to the separating power, which is a dimensionless measure for the maximum separation that can be obtained only attotalreflux.A clear picture of the influence on the separating performance of a fractionating column exerted by variation of the reflux ratio can be gained by a new graphical representation, plotting separating performances against draw‐off percentages, instead of against reflux ratios.The graph gives a simple illustrative explanation of a number of empirical distillation rules.
Mixed carboxylic acid anhydrides: I. Acetic‐formic anhydride
Authors: Stevens W. , van Es A. 
Published: September 2010

AbstractThe identity and purity of acetic‐formic anhydride prepared from ketene and formic acid have been established by means of N.M.R. and I.R. absorption data. On the basis of these data the presence of this mixed anhydride in the formylating reagent obtained from acetic anhydride and formic acid, could be proved and the composition of the reagent established. Indications were found, that on standing, acetic‐formic anhydride disproportionates into acetic anhydride and formic anhydride and that formic anhydride is also present in the formylating reagent.
Mollisin, a naturally occurring chlorine‐containing quinone: Part II,. The structure of mollisin
Authors: Overeem J. C. , van der Kerk G. J. M. 
Published: September 2010

AbstractNew evidence is presented which shows that the yellow pigment from the fungus Mollisia caesia, mollisin, formerly believed to be 8‐acetonyl‐2,3‐dichloro‐5‐hydroxy‐7‐(or 6)methyl‐naphthoquinone‐1,4 is in fact 8‐dichloro‐acetyl‐5‐hydroxy‐2,7‐dimethyl‐naphthoquinone‐1,4.
N.M.R. studies of non‐bonded interactions in azabiphenyls
Authors: Murrell J. N. , Gil V. M. S. , van Duijneveldt F. B. 
Published: September 2010

AbstractA study of the proton N.M.R. spectra of (aza)biphenyls at several temperatures and in various solvents has shown that the planarity of these molecules increases in the series biphenyl, 2‐phenylpyridine, 2‐phenylpyrimidine and 2,2′‐bipyridyl, the latter compound being mainly trans at room temperature. It follows that an ortho‐ortho CH… N interaction is less repulsive than a corresponding CH… CH interaction. Rapid rotation in molecules having one o‐nitrogen atom is found to persist at −65 °C.
The conformation of non‐aromatic ring compounds XXVI the absolute configuration of 2α,3β‐dibromo‐5α‐cholestane
Authors: van Heijkoop E. , Geise H. J. , Romers C. 
Published: September 2010

AbstractThe absolute configuration of 2α, 3β‐dibromo‐5α‐cholestane has been determined using the anomalous dispersion of X‐rays by the bromine atoms. The results agree with the generally accepted configuration of the steroids.
Enthalpies of solvation of alkali halides in formamide. II.: Evaluation of experimental ionic enthalpies of solvation
Authors: Somsen G. 
Published: September 2010

AbstractFrom known lattice enthalpies and measured enthalpies of solution in formamide the enthalpies of solvation of 18 alkali halides in this solvent are calculated. A plot of the enthalpies of solvation of a series of alkali halides with one common cation against the reciprocal crystal radii of the anions is linear. Application of the extrapolation method results in a primary splitting of the total enthalpies of solvation of the salts into a set of experimental ionic enthalpies of solvation. As in water, the enthalpies of solvation in formamide for anions are larger than those for cations of the same size. The difference is smaller, however. The relation with absolute ionic enthalpies of solvation is discussed.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophiles (V): Conversion of some 2‐alkyl‐, 2‐aryl‐ and 2,5‐dialkyl‐4‐chloropyrimidines by potassium amide in liquid ammonia into 4‐alkyl derivatives of 2‐alkyl‐ or 2‐aryl‐s‐triazines
Authors: van der Plas H. C. , Haase B. , Zuurdeeg B. , Vollering M. C. 
Published: September 2010

AbstractReactions of 2‐methyl‐, 2‐ethyl‐, 2‐phenyl‐, 2,5‐ and 2,6‐dimethyl‐4‐chloropyrimidine with potassium amide in liquid ammonia have been investigated.Together with aminations leading to the formation of 4‐amino compounds, conversions involving a ring transformation were found to occur. The latter process occurred in aminations of the three first‐mentioned substances, 2,4‐dimethyl‐, 2‐ethyl‐4‐methyl‐ and 4‐methyl‐2‐phenyl‐s‐triazine respectively being formed. Also from 4‐chloro‐2,5‐dimethylpyrimidine a s‐triazine derivative, 4‐ethyl‐2‐methyl‐s‐triazine, was obtained. The last‐mentioned reaction indicates that in the ring transformation pyrimidynes are not involved and that the 5‐methyl group and the 5‐carbon atom of the pyrimidine ring contribute to the formation of the ethyl group in the reaction product.A mechanism for the ring transformation is proposed.
The system NbCl5Nb2O5. IV. The T‐x projection
Authors: Hart W. 'T‐x , Meyer G. 
Published: September 2010

AbstractAn investigation into the occurrence of compounds in the binary system NbCl5Nb2O5is described together with the determination of the phase‐compositions of the three‐phase equilibria SLG and SSG, as a function of temperature. Finally, the situation of part of the critical curve is established.
The diffusion potential between electrolyte solutions in different solvents: Some quantitative data about the contribution of the transport of solvent molecules through the boundary layer to the diffusion potential
Authors: Alfenaar M. , de Ligny C. L. , Remijnse A. G. 
Published: September 2010

AbstractIn the diffusion through the boundary layer between electrolyte solutions in different media, the transport of uncharged particles comes into play. The contribution of this transport to the diffusion potential is measured for alkali halide solutions in methanol‐water mixtures. Using Δμ0‐values of individual ions in methanol‐water mixtures, the total diffusion potentials are calculated.It can be concluded that the diffusion potential between electrolyte solutions in different solvents depends mainly on the primary medium effect.
Complexes with ligands containing nitrile groups. Part II. Methyl cyanide complexes of some mono‐ and di‐valent metal chlorides with tin tetrachloride
Authors: Reedijk J. , Groeneveld W. L. 
Published: September 2010

AbstractA number of complexes with the general formula M(CH3CN)n(anion)m, is reported. The anions are SnCl62− and (SnCl5 · CH3CN)−. The cations M are the monovalent ions: Li, Na, Cu, (C2H5)4N, and the divalent ions: Be, Mg, Ca, Sr, Ba, Mn, Fe, Co, Ni, Cu, Zn. Most of the cations are completely solvated by the methyl cyanide in these complexes.The compounds were synthesized by reaction of SnCl4 with the metal chlorides in methyl cyanide. In some cases this chloride‐ion transfer was studied spectrophotometrically and conductometrically. The ligand‐field splitting parameter (Dq) and Racah parameter (B) are calculated for some M(CH3CN)62+ ions.Several complexes proved to be isomorphous from their X‐ray powder‐patterns. Information about the structure of the anions was obtained from far‐infrared and Raman spectra. The ternary phase‐diagram CoCl2‐SnCl4‐CH3CN is discussed.
The universal pH‐scale in methanol and methanol‐water mixtures
Authors: Alfenaar M. , de Ligny C. L. 
Published: September 2010

AbstractThe universal pH‐scale in methanol‐water mixtures and in methanol is defined, in terms of the pHst values of standard buffer solutions in these solvents as well as in terms of the pHst values of aqueous standard buffer solutions and the values of Ej(H2O) ‐ Ej(S)/0.05916. The accuracy is satisfactory. (0.01 to 0.12 pH‐units in 0‐90% methanol and 0.27 pH‐units in methanol).
Sulfur compounds in free radical reactions. Part III: Thermal decomposition of triphenylmethyl thionitrite
Authors: van Zwet H. , Kooyman E. C. 
Published: September 2010

AbstractTriphenylmethyl thionitrite appears to be a convenient source of triphenylmethylthiyl radicals (Ph3CS•); the thermolysis Ph3CSNO → Ph3CS• + NO is reversible. The thiyl radicals may react with aralkyl hydrocarbons to form the corresponding thiol.
The photolysis of cyclopropanecarbaldehyde at 313 nm, a possible example of triplet‐triplet annihilation
Authors: Overwater J. J. I. , Cerfontain H. 
Published: September 2010

AbstractCyclopropanecarbaldehyde has been photolysed in the gas‐phase with light in the 313 nm region at temperatures from 50 to 190 °C and at various aldehyde pressures. The most important gaseous reaction products are carbon monoxide, propene and cyclopropane. The quantum yield of propene, which is practically independent of temperature, decreases with increasing aldehyde pressure. The quantum yield of cyclopropane increases with both temperature and aldehyde pressure but decreases with increasing intensity of the absorbed light.It is proposed that propene is formed by intramolecular decomposition of singlet excited cyclopropanecarbaldehyde, whereas cyclopropane ultimately results from a radical decomposition of triplet cyclopropanecarbaldehyde.
Biologically active prostaglandins from some new odd‐numbered essential fatty acids
Authors: Beerthuis R. K. , Nugteren D. H. , Pabon H. J. J. , van Dorp D. A. 
Published: September 2010

AbstractAll‐cis 8,11,14‐octadecatrienoic‐(18:3 ω4), nonadecatrienoic‐(19:3 ω5), heneicosatrienoic‐(21:3 ω7), docosatrienoic‐(22:3 ω8) and 5,8,11,14‐nonadecatetraenoic‐(19:4 ω5) and heneicosatetraenoic‐(21:4 ω7) acid were synthesized. These fatty acids were used for a study of their enzymic conversion into homologues of prostaglandin E1 (PGE1) and E2 (PGE2) by a particulate fraction of sheep vesicular glands. Moreover, their essential fatty acid (EFA) activities in the rat were determined.18:3 ω4 and 22:3 ω8 could not be converted into prostaglandin‐like materials; 19:3 ω5, 19:4 ω5, 21:3 ω7 and 21:4 ω7 yielded ω nor PGE1, ω nor PGE2, ω homo PGE1 and ω homo PGE2 respectively, the biological activities of which were comparable with those of PGE1 and PGE2, when tested on guinea pig ileum, rat blood pressure and ADP‐induced platelet aggregation. The conversion rates were compared with those of arachidonic acid (20:4 ω6) and dihomo‐y‐linolenic acid (20:3 ω6) and appeared to be, in decreasing order: 20:4 ω6 > 20:3 ω6 > 21:4 ω7 > 19:4 ω5 > 21:3 ω7 > 19:3 ω5.Only the fatty acids that yielded biologically active prostaglandins showed considerable EFA‐activities; 18:3 ω4, 20:3 ω7 and 22:3 ω8 had no EFA‐activity. The ratios of the EFA‐activities of the fatty acids correlate roughly with the ratios of their conversion rates into prostaglandins.The fatty acids obtained from the liver mitochondria of rats fed with the various fatty acids were analysed. A considerable incorporation was found for the C19 and C21 acids. The C19 and C21 trienoic acids were dehydrogenated for the greater part to their corresponding tetraenoic acids, whereas the C19 acids were partly chain‐lengthened and further dehydrogenated to 21:5 ω5. The conclusion is that all‐cis fatty acids with the structure:CH3(CH2)n(CHCH‐CH2)4(CH2)2COOH, in which n = 3, 4 or 5, and those which can be converted by the rat into them, have EFA‐activity.