bluuebunny/crossref_metadata_2025_split huggingface dataset:
The chemistry of cycloheptatriene Part VI: Interaction of 2,6‐dimethylphenol and tropylium salts
Authors: van Helden R. , ter Borg A. P. , Bickel A. F. 
Published: September 2010

AbstractThe interaction of 2,6‐dimethylphenol and tropylium salts has been investigated. When the reaction is conducted in acetic acid solution cycloheptatriene and (4‐hydroxy‐3,5‐dimethylphenyl)tropylium salts (III) are formed. The yield of the latter depends on the anion present; it increases in the order: ClO4− < BF4− < Cl− < CH3COO−. This reaction proceeds in two steps, viz. the primary formation of 2,6‐dimethyl‐4‐tropylphenol (IV) which then, by hydride ion transfer to tropylium ion, yields III. Isolation of the intermediate phenol was possible by the use of the heterogeneous system acetic acid ‐ water/hexane; upon reaction with tropylium salts it gave III.
The ultra‐violet absorption spectrum of iodides in dioxan‐water mixtures
Authors: Rummens F. H. A. 
Published: September 2010

AbstractThe influence of ion‐pairing on the U.V. absorption of the iodide ion is described. Lithium, potassium and tetra‐n‐butylammonium iodides were used along with mixtures of dioxan and water as solvents. It is shown that not only are effects attributable to ion‐pairing detectable, but that different effects can be associated with the presence or absence of solvent molecules between the ions of the ion pair.
Soap films as a tool for the study of colloidal stability
Authors: Lyklema J. 
Published: September 2010

AbstractThe same factors that govern the stability of hydrophobic colloidal systems influence the behaviour of thin detergent films. The study of soap films can therefore clarify many of the problems relating to colloidal stability, and vice versa. The advantages and limitations of the soap film approach are discussed. An interesting way of performing such experiments is to investigate the thickness of slowly formed soap films. Some results of this method are set forth.
A thermodynamic study of p‐chloroaniline
Authors: Aboul‐Seoud A. , El‐Hady A. 
Published: September 2010

AbstractThe distribution of p‐chloroaniline between heptane and aqueous sodium chloride solutions was studied at 15°, 25° and 35°. The data obtained was used to calculate the activity of the amine under the different conditions.The hydrolysis of p‐chloroaniline hydrochloride was studied at different temperatures, different concentrations and in presence of different concentrations of sodium chloride, by the distribution method. The ratio of the activity coefficients of hydrogen and p‐chloroanilinium ions (γH/γAnil) was calculated for the different conditions. The relationship between the activity of the free amine in water, and salt concentration, was studied.
Chemistry of acetylenic ethers LXII: Tertiary phosphines with an acetylene‐phosphorus bond
Authors: Voskuil W. , Arens J. F. 
Published: September 2010

AbstractA number of dialkylphosphinoethynes R2PC≡CH were prepared from chlorodialkylphosphines and ethynylmagnesium bromide. With di‐n‐butylphosphinoethyne the following experiments were performed.From the lithium compound LiC≡CP(n•C4H9)2 it was possible to obtain 1‐dibutylphosphinoalkynes (n•C4H9)2PC≡CR and dibutylphosphinoethynylcarbinols (n•C4H9)2PC≡CC(OH)R′R″ in liquid ammonia.With diethylamine and paraformaldehyde, dibutylphosphinoethyne gave no normal Mannich reaction, since acetylene separated off and the phosphine oxide (n•C4H9)2P(=O)CH2N(C2H5)2 was formed.By free‐radical addition of ethanethiol, (n•C4H9)2PCH = CHSC2H5 was obtained.During the reaction of organometallic compounds with dibutylphosphinoethyne we observed breaking of the P‐C ≡ bond. Further investigation proved that a nucleophilic substitution on phosphorus took place. On the strength of the reactions which are involved in this (see the scheme on p. 6) new methods could be developed for the replacement of acetylene‐hydrogen atoms by a dialkylphosphino group. These are based on reactions of the acetylene anion with RSPR2 or ROPR2. From phenyllithium and bis‐(dibutylphosphino)ethyne, mono(dibutylphosphino)ethyne and dibutyl‐phenylphosphine were obtained.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia: I. Experiments with alkyl halides
Authors: Beverloo A. , Dieleman M. C. , Verkade P. E. , de Vries K. S. , Wepster B. M. 
Published: September 2010

AbstractThe reaction of alkyl halides with solutions of alkali metals in liquid ammonia leads to mixtures of alkane, alkene, bialkyl, and alkylamine in proportions depending upon the nature of the reactants and upon the reaction conditions.Product compositions have been determined for eleven of the twelve butyl chlorides, bromides, and iodides. Rearrangement of the carbon skeleton does not occur. Sodium and lithium in liquid ammonia are especially useful for reducing chlorides almost quantitatively to the corresponding hydrocarbons with few or no by‐products.
Preparation of 2‐fluoroquinoline and 2,6‐difluoropyridine by halogen exchange
Authors: Hamer Jan , Link W. J. , Jurjevich A. , Vigo T. L. 
Published: September 2010

AbstractThe syntheses of 2‐fluoroquinoline and 2,6‐difluoropyridine in yields of respective 60% and 52% have been accomplished by treating the corresponding chloro‐compounds with anhydrous potassium fluoride in dimethyl sulfone. Under similar conditions, 2‐chloropyridine did not yield appreciable amounts of 2‐fluoropyridine.
Thermodynamic properties of quinol clathrates III
Authors: Helle J. N. , Kok D. , Platteeuw J. C. , van der Waals J. H. 
Published: September 2010

AbstractThe Gibbs free‐energy difference between β‐ and α‐quinol has been determined from the solubility of quinol in n‐propanol and the vapour pressure of the solutions. It was found that μQβ — μQα = 0.084 ± 0.003 kcal/mole, in very good agreement with the value predicted by the statistical theory from the equilibrium composition of the argon clathrate at 25°.The dissociation pressure of xenon‐quinol clathrate at 25° is 0.058 atm.
Preparation of adipic acid by oxidation of cyclohexanol and cyclohexanone with nitric acid: Part I. Reaction mechanism
Authors: van Asselt W. J. , van Krevelen D. W. 
Published: September 2010

AbstractThe oxidation of cyclohexanol with nitric acid to adipic acid proceeds via two stable intermediates known from the literature1 viz. 6‐hydroxyimino‐6‐nitro hexanoic acid and the hemihydrate of 1,2‐cyclohexanedione, two substances forming beside each other in a given ratio. This ratio can be calculated as a function, of the temperature and of the nitric acid and nitrous acid concentrations. The nitrous acid plays a very important part in the oxidation process. The oxidation of cyclohexanone proceeds in the same way as that of cyclohexanol, provided sufficient nitrous acid is present. In the absence of HNO2 the oxidation does not proceed at all at low temperatures.The catalysts used ‐ ammonium vanadate and copper nitrate ‐ have very different functions. Under the influence of the vanadate the hemihydrate of cyclohexanedione is rapidly converted to adipic acid, whereas in the absence of vanadate this substance is slowly broken down to glutaric acid, succinic acid and oxalic acid. Copper is effective only at higher temperatures where it prevents the further break‐down of unstable intermediates.
The preparation and reactions of some rhodanines
Authors: Nederlof A. 
Published: September 2010

Abstract3,3′‐Diethyl‐Δ5,5′‐birhodanine (III, R  C2H5) was obtained as a by‐product from the reactions of 3‐ethylrhodanine with 2,4‐dinitrobenzaldehyde and 1‐chloro‐2,4‐dinitrobenzene under suitable conditions. The synthesis of 5‐arylidene substituted rhodanines was achieved from condensations of rhodanines with anils of aromatic aldehydes in glacial acetic acid. III (R  C2H5, CH2 · CHCH2 and CH2COOC2H5) were prepared by heating the appropriate rhodanines in pyridine containing p‐toluenesulphonyl chloride. Reduction of III with zinc and glacial acetic acid gave the corresponding 5,5′‐birhodanines, which were easily auto‐oxidised in solutions to the related III. Rhodanine and some of its congeners react with 1‐chloro‐2,4‐dinitrobenzene in ethanol containing sodium acetate to give 2,2′,4,4′‐tetranitrodiphenyl sulphide. The methylene group of 3‐aminorhodanine reacted with p‐nitrobenzaldehyde in boiling ethanol, while the amino group was attacked when the reaction was carried out in glacial acetic acid at room temperature. Pyridine solutions of 5‐unsubstituted rhodanines were unstable.
Microbiological conversion of 19‐nortestosterone: (II) 10‐ and 11‐hydroxylation
Authors: de Flines J. , van der Waard W. F. , Mijs W. J. , Szpilfogel S. A. 
Published: September 2010

AbstractFermentation of 19‐nortestosterone with Curvularia lunata or with Botrytis paeoniae yielded mainly the 10β‐hydroxy‐derivative. Fermentation with Aspergillus ochraceus afforded the 11α‐hydroxy‐derivative in good yield.10β‐Hydroxy‐19‐nortestosterone with Corynebacterium simplex yielded 10β, 17β‐dihydroxy‐19‐norandrosta‐1,4‐dien‐3‐one.
Separation of some DL‐amino acids into their optical isomers by paper adsorption chromatography
Authors: de Ligny C. L. , Nieboer H. , de Vijlder J. J. M. , van Willigen J. H. H. G. 
Published: September 2010

AbstractA systematic research was made into the conditions producing optimum separation of the optical isomers of amino acids by paper chromatography, using as pilot substances racemic mixtures of the amino acids histidine, tryptophan and kynurenin and methanol‐water mixtures as eluents. The optimum separations, i.e. the smallest ratios of the moving‐rates of the slow and the fast component, were obtained by elution with a 90 vol% methanol‐water mixture at as low a temperature as possible (in our case −15°). In this way the separation of the optical isomers of dl‐cystine by paper chromatography, which has not yet been reported, could be accomplished.
The use of potassium chloride as a standard substance in solution calorimetry
Authors: Somsen G. , Coops J. , Tolk M. W. 
Published: September 2010

AbstractThe integral heats of solution of some samples of potassium chloride have been measured carefully with an adiabatic calorimeter. The results indicate that it is necessary to revise the value of the heat of solution of potassium chloride in water.
Investigations on pyrazine derivatives VIII: On the preparation of some aminopyrazines by the Curtius reaction
Authors: Schut W. J. , Mager H. I. X. , Berends W. 
Published: September 2010

AbstractThe possibility of preparing 2‐aminopyrazine 5‐carboxylic acid and some of its derivatives by the Curtius reaction was investigated. The final step could be accomplished satisfactorily especially by hydrogenolysis or acid hydrolysis of the corresponding benzylurethanes.
Internal reactions in the Grignard‐complex containing compounds with alkoxy‐groups: Part II. Cyclic acetals
Authors: Blomberg C. , Vreugdenhil A. D. , Homsma T. J. 
Published: September 2010

AbstractIf one molar equivalent of 2‐methyl‐, 2‐ethyl‐ or 2‐n‐propyl‐1,3‐dioxolane is used for the preparation of Grignard‐reagents in benzene, the five‐membered hetero‐ring is opened with formation of a magnesium halide 2‐alkoxyethan‐1‐olate.The steric and electronic effects of the alkyl groups of the Grignard‐reagent and those of the dioxolane molecule are discussed.
The self‐condensation of sodium 2,4,5‐trihalothiophenolates
Authors: van Zwieten P. A. , Seutter E. , Huisman H. O. 
Published: September 2010

AbstractThe formation of polymeric materials from sodium 2,4,5‐trichloro‐ and sodium 2,4,5‐tribromothiophenolates is described. The reaction takes place upon heating the sodium thiophenolates in high‐boiling solvents. So far no evidence is available for the structures of these polymers.
The halogenation of aromatics: Part VIII. Transbromination of toluene and chlorobenzene with bromobenzene under the influence of aluminium bromide‐[82 Br]
Authors: Louw R. , Kooyman E. C. 
Published: September 2010

AbstractTransbromination of chlorobenzene and of toluene with bromobenzene under the influence of aluminium bromide‐[82 Br] is accompanied by some bromine exchange between organic and inorganic bromides. However, since many bromine atoms are transferred for every bromine atom exchanging with the catalyst, the bromine atoms present in the brominating species (e.g. Br⊕Al2Br7⊖) are not in a state of rapid equilibration. The ratio of transfer and exchange is appreciably greater for toluene than for chlorobenzene as the acceptor.
Reactions of aliphatic halides with solutions of alkali metals in liquid ammonia: II.The behaviour of some arylcarbinyl chlorides towards solutions of sodium in liquid ammonia
Authors: Verkade P. E. , de Vries K. S. , Wepster B. M. 
Published: September 2010

AbstractThe behaviour of some primary, secondary, and tertiary arylcarbinyl chlorides towards solutions of sodium in liquid ammonia has been studied. Particular attention has been devoted to the biaralkyls formed.
Phosphorus metabolism and the photoproduction of oxygen and hydrogen in anaerobic chlorella
Authors: Lindeman W. , Spruit C. J. P. 
Published: September 2010

AbstractThe concentrations of oxygen and of phosphorylated intermediates of the photosynthetic carbon cycle have been followed simultaneously in illuminated suspensions of anaerobically adapted Chlorella cells. Initially, very little phosphoglyceric acid is available, and “reducing power” generated by illumination, is utilized chiefly by an active hydrogenase. In the presence of sufficiently high concentrations of carbon dioxide, phosphoglyceric acid is formed from ribulose diphosphate and competes with the hydrogenase for photochemical reducing power. As soon as the oxygen produced photochemically has reached a concentration sufficient to inhibit the hydrogenase, the reducing power is used up entirely in normal photosynthesis.
Oxidative decarboxylation of cyclohexanecarboxylic acid
Authors: Bigot J. A. , Kerkhoffs P. L. 
Published: September 2010

AbstractCyclohexanecarboxylic acid is converted to a mixture of cyclohexanone and cyclohexene by reacting it at temperatures around 200° with an oxygen‐containing gas and steam in the presence of metal‐salt catalysts.
Miscellaneous glycerol derivatives: II Diacid triglycerides
Authors: Verkade P. E. 
Published: September 2010

AbstractBelow some data are given concerning a number of diacid triglycerides which have been synthesized in my laboratory in the course of time and about which (for reasons which are irrelevant in this context) nothing has ever been published. The preparation invariably took place in the familiar way, i.e. by the action of an acyl chloride on a mono‐ or a diglyceride at room temperature, or sometimes at 35‐40°, in the presence of pyridine and of chloroform or benzene as a neutral solvent; the yields were always very good.With the triglycerides, polymorphism is a very frequently occurring phenomenon. I cannot therefore guarantee that we always obtained the most stable modification of the compounds prepared by us.
Heat of dissociation of hexaphenylethane as measured by ESR: (Short communication)
Authors: Fleurke K. H. , de Jong J. , Nauta W. Th. 
Published: September 2010

AbstractThe heat of dissociation of hexaphenylethane in m‐xylene as a solvent, measured by means of electron spin resonance, amounts to 10.9 ± 0.29 (2.7%) kcal/mol.The ESR method appears to have important advantages over other techniques for this purpose.
Oxidation of propene‐1‐14C to acrolein on copper catalysts
Authors: Sixma F. L. J. , Duynstee E. F. J. , Hennekens J. L. J. P. 
Published: September 2010

AbstractPropene‐1‐14C was partially oxidised with air to acrolein on a copper catalyst. The acrolein formed was degraded: equal amounts of radioactivity were found on carbon atoms 1 and 3, while essentially no radioactivity was found on the middle carbon atom (2). The “unreacted” propene was also degraded: a major part of the radioactivity was still on carbon atom 1, while a small part (10‐20%) was on carbon atom 3; no radioactivity was found on the middle carbon atom (2). These facts indicate that the oxidation of propene to acrolein on a copper catalyst takes place via a symmetrical intermediate.Partial isomerisation of unreacted propene also occurred when copper shavings were used as a catalyst. When D2O was present during the reaction, the unreacted propene was monodeuterated to only a very small extent (∼2%).
Thermal substitution reactions of cupric benzoate III
Authors: Schoo W. , Veenland J. U. , de Boer Th. J. , Sixma F. L. J. 
Published: September 2010

AbstractAmong the reaction products of cupric benzoate and ammonia a small amount of aniline is found. Using [1‐14C]‐benzoic acid the position of the amino group is identified as ortho in relation to the original carboxyl group.
Synthesis and absolute configuration of Tanret's (‐)‐pelletierine
Authors: Beyerman H. C. , Maat L. 
Published: September 2010

AbstractThe synthesis is described of (‐)‐pelletierine picrate identical with Tanret's pelletierine picrate from Punica granatum L. and of its antipode by oxidation, respectively, of (‐)‐ and of (+)‐sedridine. The sedridines are alkaloids with known absolute configuration of the piperidine asymmetric carbon atom. From this follows the Ds‐configuration of (‐)‐pelletierine.
Efficiency of chromatographic procedures: III. The efficiency of various kinds of Whatman paper for the separation of amino‐acids
Authors: de Ligny C. L. , Schmidt H. M. , de Vries W. 
Published: September 2010

AbstractThe efficiency of ten kinds of Whatman paper for the separation of amino‐acids with a 4 : 1 : 5 butanol‐acetic acid‐water mixture has been investigated.
New musk odorants V: A new synthesis of polyalkylindanes starting from styrenes
Authors: Spoelstra D. B. , Weber S. H. , Kleipool R. J. C. 
Published: September 2010

AbstractPolyalkylindanes of the type described in earlier communicationsS. H. Weber, D. B. Spoelstra and Ernest H. Polak, Rec. trav. chim. 74, 1179 (1955).
S. H. Weber, J. Stofberg, D. B. Spoelstra and R. J. C. Kleipool, ibid. 75, 1433 (1956).
may also be prepared by condensation of styrenes and alkenes under the influence of suitable catalystsThis new synthesis of polyalkylindanes is the subject of French Patent, 1, 109, 699 of Oct. 10, 1954, assigned to Polak's Frutal Works Inc., others pending.
.
Investigations on organotin compounds XIX: The preparation of some organotin compounds with heterocyclic nitrogen bound to tin
Authors: Luijten J. G. A. , van der Kerk G. J. M. 
Published: September 2010

AbstractProcedures are given for the preparation of 20 organotin compounds in which a trialkyl‐ or triphenyltin group is bound to nitrogen in pyrrole, pyrazole, benzpyrazole, imidazole, 1,2,4‐triazole, benzimidazole, 1,2,3‐benztriazole, 1,2,3‐triazole and 3‐amino‐1,2,4‐triazole. In addition, the preparation is described of two dialkyldi‐1,2,4‐triazolyltin compounds.
On the determination of tropan‐3‐one in the form of its reineckate
Authors: Beyerman H. C. , Enthoven P. H. , Verkade P. E. 
Published: September 2010

AbstractThe use of ammonium reineckate for the isolation and quantitative determination of tropan‐3‐one formed in Schöpf reactions, as recommended by Gál, Simonyi, and Tokár, is studied and appears to be by no means advisable.
Square wave conductometry
Authors: Wijnen M. D. , Ijzermans A. B. , Schmieman J. H. 
Published: September 2010

AbstractTheoretical and practical aspects of square wave conductometry are discussed. Equilibrium conditions for a simple bridge circuit are compared with those for classical sine wave conductometry. It is shown that square wave conductometry is less dependent on the choice of the cell parameters.As an example, square wave conductometry is applied to the titration of hydrochloric acid and acetic acid with sodium hydroxide, using both wire and plane electrodes. The influence of the presence of a redox couple upon the equilibrium condition appears to be negligible in square wave conductometry.
The reaction of methylene with ethers
Authors: Frey H. M. 
Published: September 2010

AbstractLittle quantitative work has been published on the reactions of methylene with ethers. Doering et al1 W. E. Doering, L. H. Knox, and M. Jones, J. Org. Chem. 24, 137 (1959)
studied the reaction of methylene with diethyl ether and found ethyl propyl ether and ethyl isopropyl ether with relative yields 55.5 : 45.5. This implies that the methylene inserts 1.2 times as rapidly in the secondary C‐H bonds as in the primary C‐H bonds. They found no evidence for any carbon rearrangement of a diethyl ether‐methylene ylid but indicated that a hydrogen rearrangement from such an “ylid” would lead to deviations from statistical attack in the required direction. Franzen and FikentscherV. Franzen, and L. Fikentscher, Annalen 617, 1, (1958).
were able to show, directly, by the use of labelled compounds that none of the insertion products arose by a carbon skeleton rearrangement. They also showed that in the reaction of methylene with diethyl ether some methyl ethyl ether is formed but no quantitative data was obtained.
Mechanism of reactions of furans I: A kinetic study of the acid‐catalyzed hydrolysis of furan and 2,5‐dimethylfuran
Authors: Stamhuis E. J. , Drenth W. , van den Berg H. 
Published: September 2010

AbstractThe kinetics of the hydrolysis of furan and 2,5‐dimethylfuran in aqueous perchloric acid solution at 25° have been investigated by spectroscopic and vapour pressure methods. The logarithm of the first order rate constant is linear in Hammett's acidity function, H0. The solvent deuterium isotope effect, kH/kD, of the hydrolysis of 2,5‐dimethylfuran amounts to 1.7.A mechanism is proposed in which the first step is a slow proton transfer to the α‐carbon atom of the furan ring.
A new method for the synthesis of α‐esters of N‐acylglutamic acids
Authors: Nefkens G. H. L. , Nivard R. J. F. 
Published: September 2010

AbstractN‐Benzyloxycarbonyl‐, N‐tosyl‐ and N‐phthaloylglutamic acids have been converted into various α‐esters by addition of an equimolecular amount of a base triethylamine or dicyclohexylamine) and treatment with an appropriate alkyl halide or dialkyl sulphate. The esters were isolated as dicyclohexylammonium salts and appeared free of the corresponding γ‐esters after one crystallization (Table I). The method surpasses older procedures by its symplicity and higher yield, but fails for the synthesis of p‐nitrophenyl or tert.butyl esters.The α‐esters of corresponding aspartic acid derivatives are not obtained in this way.
Investigations on organotin compounds. XXI: The preparation of organotin‐substituted acetylenes by the decarboxylation of organotin acetylenecarboxylates
Authors: Luijten J. G. A. , van der Kerk G. J. M. 
Published: September 2010

AbstractA number of triorganotin salts of acetylenemono‐ and di‐carboxylic acids upon being heated lose carbon dioxide to give organotin‐substituted acetylenes.Some others decompose in an irregular way and in one case simultaneous decarboxylation and disproportionation occurs.Tributyltin azide adds to diethyl acetylenedicarboxylate with the formation of 1‐tributylstannyl‐4,5‐di‐ethoxycarbonyl‐1,2,3‐triazole.
Addition of organotin hydrides across the nitrogen‐nitrogen double bond; Hydrogenolysis of the tin‐nitrogen bond by organotin hydrides
Authors: Noltes J. G. 
Published: September 2010

AbstractTriorganotin hydrides readily add across the nitrogen‐nitrogen double bond of azobenzene and diethyl azodicarboxylate to produce organotin‐substituted hydrazine derivatives.The reduction of these azo compounds and of aryl isocyanates by triorganotin hydrides proceeds by formation of a 1: 1 adduct and subsequent hydrogenolysis of the tin‐nitrogen bond of the adduct.
Spectropolarimetry II. The optical rotatory dispersion of α‐amino‐acids and α‐hydroxy‐acids
Authors: Dirkx I. P. , Sixma F. L. J. 
Published: September 2010

AbstractThe rotatory dispersion of 26 amino‐acids and 5 hydroxy‐acids was studied. It was found that the carboxyl absorption‐band at about 205 nm to 210 nm is optically active. L‐Amino‐acids as well as L‐hydroxy‐acids show a positive Cotton effect. For a number of amino‐acids a correlation exists between peak‐height and molecular structure. Except for proline, hydroxy‐proline and cystine, all acids studied show very similar rotatory dispersion curves.