bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemistry of acetylenic ethers XXXIII: The addition of ethoxyethyne to diphenylketene
Authors: Nieuwenhuis J. , Arens J. F. 
Published: September 2010

AbstractEthoxyethyne reacts easily with diphenylketene. I. The nature of the product depends upon the reaction temperature and the solvent. In benzene at room temperature, a 34% yield of 1‐phenyl‐2‐ethoxy‐4‐hydroxynaphthalene, VI, is obtained, whereas in nitromethane at −20° the product is 1,1‐diphenyl‐2‐ethoxycyclobut‐2‐ene‐4‐one. XXX. These structures have been proved by several reactions and by synthesis of degradation products. Similar reactions have been performed between 1‐ethoxy‐1‐propyne (XXXIV, R = C2H5), 1‐methoxy‐1‐propyne (XXXIV, R = CH3) and diphenylketene, I, yielding again acyclobutenone, XXXV, and a naphthol, XXXVI.
Chemistry of acetylenic ethers XXXV. Reactions of alkali metal derivatives of ethoxyethyne and of ethylthioethyne with epichlorohydrin
Authors: Vollema G. , Arens J. F. 
Published: September 2010

AbstractThe reaction between epichlorohydrin and ethylthioethynyl‐lithium affords the enynol V and furfuryl ethyl sulphide VI. The same reaction with ethoxyethynyl‐lithium, however, produces the epoxy compound VII.
The effects of ultraviolet light on some components of the nucleic acids: III. Apurinic acid
Authors: Beukers R. , Ijlstra J. , Berends W. 
Published: September 2010

AbstractApurinic acid, prepared from deoxyribonucleic acid, is destroyed by ultraviolet light much more rapidly than would be expected from the behaviour of the component pyrimidine‐nucleotides under this radiation.It is confirmed by analysis that both thymine and cytosine are sensitive. The destruction of thymine is supposed to be due to the occurrence of this pyrimidine in a more sensitive form, presumably comparable to the form present in a frozen solution.Upon adding an amount of adenine comparable to that of the purines removed, to apurinic acid, the decrease in extinction on irradiation resembles closely that of deoxyribonucleic acid.Consequently, it seems likely that the purines in deoxyribonucleic acid protect the pyrimidines to a certain extent against the U.V. radiation and that the sensitivity of deoxyribonucleic acid to U.V. radiation is caused by the pyrimidines present as constituent parts of the molecule. The primary action of this radiation on living cells may be caused by destruction of the pyrimidines in the nucleic acids.
Chemistry of acetylenic ethers XXXVI. Preparation and properties of some 1‐alkylthio‐1‐alkynes
Authors: Boonstra H. J. , Brandsma L. , Wiegman A. M. , Arens J. F. 
Published: September 2010

AbstractAldehydes can be converted into 1‐alkylthio‐1‐alkenes II (thioenol ethers) via either α‐chlorothioethers I by elimination of hydrogen chloride or, better, thioacetals VI by acid catalysed elimination of thiol. Bromination of the thioenol ethers II followed by subsequent dehydrobromination with diethylaniline and potassium hydroxide affords 1‐alkylthio‐1‐alkynes V, which are relatively stable liquids.Electrophilic as well as nucleophilic additions to 1‐ethylthio‐1‐propyne proceed slowly. The orientations during these additions are similar to those observed earlier for alkylthioethynes HCCSR; that is to say, that electrophilic as well as nucleophilic reagents attack the β carbon atom. This again39 suggests that the direction of the polarisability of the alkylthio group depends on the character of the substance added. During the approach of electrophilic reagents the polarisation is magnified image, but nucleophilic reagents induce the reversed polarisation magnified image.
The temperature variation of orthobaric density difference in liquid‐vapour systems: V. Amines
Authors: Costello J. M. , Bowden S. T. 
Published: September 2010

AbstractThe density of a series of aliphatic amines together with that of aniline and its methyl derivatives has been measured over ranges of temperature below and above the normal boiling point. The variation of orthobaric density difference may be represented by equations of the Verschaffelt type using estimated values of the critical temperature. On this basis it is found that the exponent for the lower members is slightly higher than that for non‐associated liquids and that its value decreases with increasing complexity of the amine. In general, the exponent for secondary amines is lower than that for primary amines, and the still lower values for tertiary amines is to be ascribed to causes other than hydrogen bonding. The behaviour of aniline and its N‐methyl derivatives is well represented by the Verschaffelt equation over a range of 300°.It is shown that the Lewis equation relating to zero and critical densities is obeyed closely by associated substances.
The vapour pressure of tungsten trioxide
Authors: Meyer G. , Oosterom J. F. , de Roo J. L. 
Published: September 2010

AbstractMeasurements of the vapour pressure of solid tungsten trioxide between 1100° and 1250° C show that these vapour pressures cannot be calculated by extrapolation from the measurements carried out by Közo Inoue between 800 and 850°.Conversely, the vapour pressure formula, which we have found, is in good agreement with the measurements between 800 and 850°.
α‐L‐Glutamyl Choline
Authors: Amiard Gaston , Heymès René 
Published: September 2010

AbstractLa N‐tritylation des diesters glutamiques, en protégeant la fonction ester en α, permet d'accéder au N‐trityl‐L‐glutamate d'α‐(β'‐chloro éthyle). Le traitement usuel par la triméthylamine suivi de la détritylation en acide acétique aqueux conduità l'α‐L‐glutamyl choline qu'on isole sous forme d'iodure et de nitrate cristallisés.
On the sulphonation of pyridine‐N‐oxide
Authors: van Ammers M. , den Hertog H. J. 
Published: September 2010

AbstractThe sulphonation of pyridine‐N‐oxide with fuming sulphuric acid and mercuric sulphate as a catalyst yields, together with the 3‐sulphonic acid as chief product, the 2‐ and 4‐isomers.
The polymerisation of 4‐chloropyridine
Authors: Wibaut J. P. , Broekman F. W. 
Published: September 2010

AbstractThe polymerisate of 4‐chloropyridine consists of a mixture of water‐soluble substances showing the properties of pyridyl‐4‐chloropyridinium chlorides. These compounds are rapidly decomposed by water, the chlorine in the pyridine ring being split off hydrolytically.From measurements on the U.V. spectra, it appears that 4‐hydroxypyridine and N(4′‐pyridyl)‐4‐pyridone are produced in the hydrolysis of the polymerisate. These compounds were isolated in the form of their picrates. In addition, two other picrates have been isolated, which are in all probability derived from compounds containing more than two pyridine rings.
The decomposition of organic hydroperoxides: Part II. The effects of magnesium and zinc stearate on 1,2,3,4‐tetrahydronaphthyl‐hydroperoxide
Authors: van Leeuwen H. B. , Wibaut J. P. , Bickel A. F. , Kooyman E. C. 
Published: September 2010

AbstractThe decomposition of 1,2,3,4‐tetrahydronaphthyl‐1‐hydroperoxide (α‐tetralyl hydroperoxide) in the presence of catalytic amounts of zinc and magnesium stearate has been investigated in chlorobenzene and other solvents. For comparison, α, α‐dimethylbenzyl hydroperoxide (α‐cumyl hydroperoxide) and tert.butyl hydroperoxide have also been decomposed in the presence of the above catalysts.With zinc stearate, α‐tetralyl hydroperoxide predominantly yields phenolic products, the zinc soap apparently acting as a Lewis acid. Hydrogen is also obtained; it is probably generated by interaction of the phenolic aldehyde formed (γ‐(ortho‐hydroxyphenyl) butyraldehyde) and the hydroperoxide. The zinc stearate shows little effect, however, on the decomposition of α‐cumyl and tert.butyl hydroperoxide.Magnesium stearate causes a free‐radical chain decomposition of α‐tetralyl hydroperoxide (see Part IH. B. van Leeuwen et al., Rec. trav. chim. 77, 17 (1958).
) yielding mainly tetralone and tetralol. This metal soap also accelerates the decomposition of tert.butyl hydroperoxide and, to a less extent, of cumyl hydroperoxide.The catalytic influence of both magnesium and zinc stearate is markedly affected by the solvents employed.
The interaction between two cylinder shaped colloidal particles
Authors: Sparnaay M. J. 
Published: September 2010

AbstractThe theory of the stability of lyophobic colloids, as given by Derjaguin and by Verwey and Overbeek for the flat‐plate model or the sphere model of colloidal particles, is applied to cylindershaped colloidal particles.Anisometry was taken into account by considering the interaction between two parallel particles and between two particles in a crossed position. Mathematical expressions are given for the repulsive and the attractive potential energy in these two cases. It should be inferred from these expressions that the behaviour of two parallel cylinders is intermediate between the behaviour of two flat plates and two spheres whereas two crossed cylinders behave in much the same way as two spheres.
The use of U.V. absorption spectra for the determination of configurations of some aromatic oximes
Authors: Rekker R. F. , Veenland J. U. 
Published: September 2010

AbstractThe U.V. absorption spectra of a series of benzophenone oximes are discussed. Notwithstanding relatively small differences in absorption of the isomers, incontestable conclusions as regards configurations can be drawn, even if only one of the conceivable isomers is available. The results agree with what might be expected on the assumption that the Beckmann rearrangement proceeds via an anti‐migration.
Studies on the oxidation of isomeric 6‐octadecenoic acids. Characterisation of 6(7)‐hydroxy‐7(6) ketostearic acids
Authors: Farooq M. O. , Osman S. M. 
Published: September 2010

AbstractOxidation of petroselinic or petroselaidic acid with neutral potassium permanganate gave mainly a mixture of two structurally isomeric hydroxy‐ketoacids, characterised as 7‐hydroxy‐6‐ketostearic acid, m.p. 77.5‐78.5 and 6‐hydroxy‐7‐ketostearic acid, m.p. 74.5‐75.0°. Lead tetraacetate is shown here to be an effective cleavage reagent for 1,2‐ketols and 1,2‐diketones. The oxidation of the cis‐ and trans‐6‐octadecenoic acids with hydrogen peroxide with and without catalyst (OsO4) has been studied. The cis‐hydroxylation of petroselinic and petroselaidic acids is also described.
A synthesis of oxytocin
Authors: Beyerman H. C. , Bontekoe J. S. , Koch A. C. 
Published: September 2010

AbstractThe synthesis is described of the “protected” linear nonapeptide: N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐isoleucyl‐L‐glutaminyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐L‐leucylglycine amide (XI). In the new reaction steps N,N′‐dicyclohexylcarbodiimide was used as sole coupling agent in combination with a variety of blocking groups.The conversion of XI into the pituitary hormone oxytocin is known.
Studies on vitamin D and related compounds IX: Remarks on the iodine‐catalyzed isomerisations of vitamin D and related compounds
Authors: Verloop A. , Koevoet A. L. , van Moorselaar R. , Havinga E. 
Published: September 2010

AbstractDetails on the iodine‐catalyzed reactions of previtamin D, tachysterol, cis‐ and trans‐vitamin D (influence of solvent, concentration, wavelength of light) are given. The possibility of a previtamin D determination based on the cis/trans isomerisation is indicated. Some results and products obtained from the iodine‐catalyzed reactions in the vitamin D3 series are reported.
Square wave electrolysis II: The cyclic current‐step method
Authors: Wijnen M. D. , Smit W. M. 
Published: September 2010

AbstractA new method, designated the cyclic current‐step method, for the evaluation of kinetic parameters of electrochemical processes (especially the exchange current j0) is introduced in addition to the well‐known (single) current‐step method. Its essential basis is that a square wave current is forced through a polarisable electrode and the voltage response of the electrode is measured.It is shown mathematically that the voltage response approaches a constant pattern when “coulomb‐symmetry” is present and a gradually changing pattern is observed when a departure from coulomb‐symmetry occurs. Even when the pattern is continuously changing due to the presence of coulomb‐asymmetry the evaluation of j0 may be easily achieved.By means of the cyclic current‐step method it is easily visualised whether or not the influence of the double layer capacity is negligible. Moreover, the method provides a ready means for the elimination of the ohmic part of the voltage response of the electrolytic cell.
The structure of the compound diphosphotrioxytetrachloride, P2O3Cl4
Authors: Gerding H. , Gijben H. , Nieuwenhuijse B. , van Raaphorst J. G. 
Published: September 2010

AbstractThe frequencies of and the polarization of most of the Raman lines of liquid P2O3Cl4 have been determined.The molecule contains an oxygen bridge connecting two magnified image groups.From the polarization measurements it is deduced that at least one symmetry element is still present in the molecule.
The Raman spectrum of an equimolar liquid mixture of sodium chloride and gallium trichloride
Authors: Gerding H. , Koningstein J. A. 
Published: September 2010

AbstractThe Raman spectrum of a liquid mixture consisting of one mole of sodium chloride with a half mole of Ga2Cl6 (one GaCl3), melting temperature 103.7°, gives indications for the presence of an equilibrium between the molecular species NaCl, Ga2Cl6 and NaGaCl4.
The action of ethyl diazoacetate on acetic anhydride
Authors: de Graaff G. B. R. , van de Kolk G. 
Published: September 2010

AbstractFrom the reaction mixture, obtained by reacting ethyl diazoacetate and acetic anhydride in the manner described in previous communications1, we have isolated ethyl acetoxyacetate, ethyl (α‐acetoxy)‐acetoacetate and 1‐acetyl‐3,4,5‐tri(ethoxycarbonyl)‐2‐pyrazoline. The reaction mechanism is discussed.
A study of the ziegler‐type combinations TiCl4‐n‐C5H11Na and TiCl4‐(C2H5)2AlBr
Authors: Havinga R. , Tan Y. Y. 
Published: September 2010

AbstractThe reaction between catalyst components has been studied and polymerization experiments carried out on ethylene using the systems pentyl‐sodium – TiCl4 (I) and diethylaluminium bromide – TiCl4 (II). Results of reduction of TiCl4 can be interpreted on the basis of the following equations: AmNa + TiCl4 → TiCl3 + NaCl + Am•, in the case of I, Et2AlBr + TiCl4 → TiX3 + EtAlX3 + Et• and EtAlX2 + TiCl4 → TiX3 + + AlX3 + Et• (X = Cl, Br), in the case of II. The occurrence of the second reaction in II was confirmed by analyses of the precipitates formed in the reaction and by reacting TiCl4 with EtAlBr2. The reducing power of the organometallic compounds examined decreases in the range: AmNa > Et2AlBr > EtAlBr2.Polymerization results with system I showed that active catalysts are obtained only with AmNa/TiCl4 mole ratios > unity. The polymer yield appeared to increase with increasing catalyst ratio. This may reasonably be explained by postulating the existence of an AmNa‐TiCl3 complex as the actual catalytic species. In this range of catalyst ratios, the intrinsic viscosities of the polyethylenes remain approximately constant.In the case of system II, polymerization results could also be interpreted by assuming the existence of one complex or a mixture of a number of complexes as the catalyst. With Et2AlBr/TiCl4 mole ratios > ∼ 2, a complex between Et2AlBr and TiCl3 (Et2AlX‐TiX3) is postulated. With catalyst ratios in the vicinity of unity and lower, ambiguous results were obtained due to the occurrence of reactions between the catalyst components during polymerization.
Investigations on herbicides III: 2,4‐Disubstituted 6‐chloro‐1,3,5‐triazines
Authors: Koopman H. , Daams J. 
Published: September 2010

AbstractIn view of their herbicidal properties a number of similarly or differently 2,4‐substituted 6‐chloro‐1,3,5‐triazines was synthesized. Their herbicidal properties are briefly discussed.
Synthesis of a tyrosine “homologue” of oxytocin
Authors: Beyerman H. C. , Bontekoe J. S. , Koch A. C. 
Published: September 2010

AbstractA synthesis is described of the “protected” decapeptide N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐isoleucyl‐L‐glutaminyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐L‐leucylglycineamide (V).Removal of the blocking groups from V followed by oxidation yielded biologically active preparations believed to contain a “homologue” of oxytocin with two consecutive molecules of tyrosine instead of one (VI). Oxytocin‐inhibiting activities of VI have been described by other investigators.
Phosphatidic acids and derivatives. IX. A new synthesis of glycolkephalins and glycerol‐α‐kephalins
Authors: Hoefnagel M. A. , Stegerhoek L. J. , Verkade P. E. 
Published: September 2010

AbstractA new synthesis of glycerol‐α‐kephalins and glycolkephalins is described. The corresponding silver benzyl diacylglycerol‐α‐phosphate or silver benzyl glycolphosphate is boiled in benzene solution with 2‐(dibenzylamino)ethyl bromide, and the O,N,N‐tribenzyl derivative of the kephalin thus obtained is converted into the kephalin by hydrogenolysis. The overall yields are 80‐90 %.
Tautomerism of hydroxypyridines (II). Bromination of 2,4‐dihydroxypyridine and its ethyl derivatives
Authors: Kolder C. R. , den Hertog H. J. 
Published: September 2010

Abstract2,4‐Dihydroxypyridine, 2‐ethoxy‐4‐hydroxypyridine, 4‐ethoxy‐2‐hydroxypyridine and 2,4‐diethoxypyridine were brominated in pyridine as solvent. It appeared that bromine enters the 3‐position during the bromination of the three first mentioned substances whereas from 2,4‐diethoxypyridine the 5‐bromo derivative is formed.Ultraviolet absorption spectra of substrates and reaction products in 50% aqueous ethanolic solution were measured. Comparison of these spectra with the known spectra of the mono‐ and dimethoxy derivatives of 2,4‐dihydroxypyridine enabled the tautomeric structures of the substances to be investigated. The course of the brominations is connected with the structure of the substrates.
Etude de L'Amphotérisme de L'Hydroxyde Germaneux par Spectrographie Infrarouge
Authors: Dupuis Mme Thérése 
Published: September 2010

AbstractL'étude de la courbe de thermolyse de l'hydroxyde germaneux préparé et isolé à l'abri de l'oxygène de l'air, confirme la composition globale GeO.1H2O. D'autre part, la comparaison des spectres d'absorption infrarouge de GeO.H2O, de GeO et de GeO2.xH2O montre que l'hydroxyde germaneux présente la structure Ge(OH)2 avec des groupements OH associés par ponts hydrogènes.
The pH of some standard solutions in methanol and methanol‐water mixtures at 25° II. Experimental Part
Authors: de Ligny C. L. , Luykx P. F. M. , Rehbach M. , Wieneke A. A. 
Published: September 2010

AbstractBy application of a method which was developed in Part I of this series the pH* of an oxalate and a succinate buffer in water, methanol‐water mixtures and methanol and that of a salicylate buffer in methanol was measured. The pH* in methanol was measured by application of both silver chloride and silver bromide electrodes: the values obtained agreed closely.
Synthesis of a tyrosine “homologue” of lysine‐vasopressin
Authors: Beyerman H. C. , Bontekoe J. S. , Koch A. C. 
Published: September 2010

AbstractThe synthesis is described of the protected linear decapeptide: N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐phenylalanyl‐L‐glutaminyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐N6‐tosyl‐L‐lysylglycineamide (II, Fig. 2).Removal of the blocking groups from II, followed by oxidation, yielded a preparation believed to contain a “homologue” of lysine‐vasopressin with two consecutive molecules of tyrosine instead of one (Fig. 1, n = 2).
Synthesis of tyrosine3‐lysine8‐vasopressin
Authors: Beyerman H. C. , Bontekoe J. S. 
Published: September 2010

AbstractThe synthesis is described of the protected linear nonapeptide: N‐benzyloxycarbonyl‐S‐benzyl‐L‐cysteinyl‐L‐tyrosyl‐L‐tyrosyl‐L‐glutammyl‐L‐asparaginyl‐S‐benzyl‐L‐cysteinyl‐L‐prolyl‐Ne‐p‐toluenesulfonyl‐L‐lysylglycineamide (II, Fig. 2) in analytically pure form.Removal of the blocking groups from II, followed by cyclization through oxidation, yielded a preparation assumed to contain an analogue of lysine8‐vasopressin with L‐phenylalanine replaced by L‐tyrosine (Fig. 1).
Investigations on pesticidal phosphorus compounds III: The structure of the reaction product of 3‐amino‐5‐phenyl‐1,2,4‐triazole and bis(dimethylamido)phosphoryl chloride (WP 155)
Authors: van den Bos B. G. 
Published: September 2010

AbstractThe structure of the reaction product (WP 155) of 3‐amino‐5‐phenyl‐1,2,4‐triazole and bis‐(dimethylamido)phosphoryl chloride is discussed. By comparing the U. V. absorption spectra of the bromo compound (X) obtained from WP 155 and the three N‐ethyl‐3‐bromo‐5‐phenyl‐1,2,4‐triazoles (VII, VIII, IX) with those of the three known N‐methyl‐3‐methyl‐5‐phenyl‐1,2,4‐triazoles (XI, XII, XIII) it may be concluded that WP 155 is 5‐amino‐1‐[bis(dimethylamido)phosphoryl]‐3‐phenyl‐1,2,4‐triazole.
Syntheses and physical constants of eleven monobranched hexadecanes
Authors: Wibaut J. P. , Brand H. 
Published: September 2010

AbstractThe syntheses of seven methylpentadecanes, 3‐ethyltetradecane, 4‐n‐propyltridecane, 5‐n‐butyldodecane and 6‐n‐pentylundecane are described. The degree of purity, determined from the melting curves, was over 99.7%. Densities and refractive indices of the hydrocarbons and the intermediate tertiary alcohols have been determined at 20 and 25°. Further, melting points and boiling points of the hydrocarbons have been measured and their infra‐red and mass spectra have been recorded.
Studies on the hypohalogenation of isomeric 6,7‐octadecenoic acids: Petroselinic and petroselaidic acids
Authors: Farooq M. O. , Osman S. M. , Siddiqui M. Saleem 
Published: September 2010

AbstractThe 6(7)‐chloro‐7(6)‐hydroxystearic acids of petroselinic and petroselaidic acids have been successfully prepared by the action of hypochlorous acid on the parent acids and by the hydrochlorination of their corresponding epoxides. The chlorohydrins on dehydrohalogenation furnished the original epoxides. The bromohydrins and iodohydrins have been prepared and were found to behave in a similar manner. The mutual transformation of the erythro‐ and threo‐6, 7‐dihydroxystearic acids through the chlorohydrins and the epoxides has been achieved.The results of these experiments lead to the conclusion that inversions of configuration occur during the replacement of the hydroxyl group by a halogen atom and also at the time of the opening and closing of the epoxide ring.
Adsorption of nitrogen on alumina at high pressure
Authors: Michels A. M. J. F. , Menon P. G. , ten Seldam C. A. 
Published: September 2010

AbstractA method is described for determining adsorption isotherms of gases on solids under elevated pressures. Results are given for nitrogen as adsorbate and alumina as adsorbent. The range covered extends to 3000 atm at temperatures between ‐ 7.6° and 100°.The volume in which the experimentally determined equation of state is valid is defined as the total volume v minus a volume v0 of the adsorbent sample inaccessible to the gas as determined with helium at low pressures.A quantity ΔG is taken as a measure of the amount of gas adsorbed. It is defined as the difference between the total amount of gas exposed to the adsorbent and the quantity which would be present in the volume v ‐ v0 at the experimental temperature and pressure if no adsorption occurred.With increase of pressure ΔG increases till a gas density ρg of about 175 amagat is reached, then it falls off (practically linearly with ρg), but rises again steeply at densities above 500 amagat. No hysteresis has been found; the alumina showed no permanent change after completion of the experiments.In the first and second range δΔG/δT is negative but in the third section it changes sign. Apparently the adsorption then changes from an exothermic to an endothermic process. An attempt is made to interpret the linear section in terms of a simple two‐phase model.