bluuebunny/crossref_metadata_2025_split huggingface dataset:
A reversible nitrate electrode
Authors: Ketelaar J. A. A. , Dammers‐De Klerk A. 
Published: September 2010

AbstractA reversible nitrate electrode is described consisting of a bristle of platinum wires through which a stream of NO2 and O2 is maintained. The behaviour of the nitrate electrode is tested with respect to stability and reversibility against a silver electrode in molten silver nitrate. The standard EMF at 600° K was found to be E° = 0.176 V against a calculated value of E° = 0.175 V.
Derivatives of amino‐acids and peptides VI: Reaction of ethoxyethyne with acylamino‐acids
Authors: Tadema G. , Harryvan E. , Panneman H. J. , Arens J. F. 
Published: September 2010

AbstractSome ethoxyvinyl esters II were prepared by addition of acylamino‐acids to ethoxyethyne (see table I). These products react with amino‐acid or peptide esters to produce peptide esters or with hydrogen chloride to yield acid chlorides.A sensitive reaction for ethoxyvinyl esters consists in treatment with bromine, where lachrymatory products (ethyl bromoacetate and acyl bromide) are formed.The reaction of ethoxyethyne with two moles of acylamino‐acids yields anhydrides of acylamino‐acids (see table II).Expectedly, anhydrides of acylamino‐acids react with aniline to produce anilides and with amino‐acid or peptide esters to produce peptide esters.Anhydrides of benzyloxycarbonylamino‐acids are thermolabile. The decomposition of the anhydride of benzyloxycarbonylglycine has been shown to produce N,N′‐bisbenzyloxycarbonylglycylglycine.
A synthesis of curcumin and related compounds
Authors: Pabon H. J. J. 
Published: September 2010

AbstractCurcumin has been prepared in 80% yield from vanillin and acetylacetone/B2O3 in the presence of tri‐sec. butyl borate and butylamine. The reaction was carried out in ethyl acetate at room temperature. Eight compounds related to curcumin have also been synthesized.
Bicyclanes III. The acid‐catalysed isomerization of perhydronaphthalene and perhydroindane
Authors: Knotnerus J. , Bickel A. F. 
Published: September 2010

AbstractThe formation of the bicyclo[3.3.0]octane ring system by isomerization of perhydronaphthalene and perhydroindane has been studied. Experiments were performed in the liquid phase under the influence of aluminium halides and in the gas phase at 300‐500° in the presence of a silica‐alumina catalyst. In both types of reaction a great number of compounds were formed.From the liquid‐phase reaction product of perhydronaphthalene a hydrocarbon carrying two methyl groups per molecule could be separated by preparative GLC; its structure could not be determined.In the liquid as well as in the gas‐phase experiments with perhydroindane the five isomeric methyl‐cis‐bicyclo[3.3.0]octanes were formed besides a large number of unidentified degradation products.Experiments with the individual isomers revealed that under the conditions of the gas‐phase reactions their stabilities differ considerably; 1‐methyl‐cis‐bicyclo[3.3.0]octane is the most stable, the endo‐2‐methyl derivative the least stable isomer.
Bicyclanes IV. Preparation and properties of the methyl‐cis‐bicyclo[3.3.0]octanes
Authors: Knotnerus J. , Schilling H. 
Published: September 2010

AbstractThe syntheses of the five methyl‐cis‐bicyclo[3.3.0]octanes are described. The exo‐3 compound could only be obtained as a mixture with an equal amount of its endo‐3 isomer.
Analysis of the nondialyzable constituents in a sample of succus liquiritiae
Authors: Berrens L. 
Published: September 2010

AbstractThe nondialyzable components in a sample of succus liquiritiae have been separated into four fractions by ammonium sulphate fractionation and precipitation with organic solvents. The chemical composition and some properties of these fractions are given.Succus liquiritiae contains a hemicellulose fraction, starch, and a fair amount of various brown peptide‐carbohydrate compounds (glycoproteins).The inhalant allergen in succ. liq. is associated with one of the glycoprotein fractions. The relation of the allergenicity of succ. liq. to browning reactions is discussed.
Some physical constants of normal saturated fatty acids and their methyl esters
Authors: Adriaanse N. , Dekker H. , Coops J. 
Published: September 2010

AbstractThe series of the normal saturated fatty acids and their methyl esters with 5 to 20 carbon chain atoms was synthesized and careful purified, mainly by fractional distillation of the methyl esters in columns with up to 58 theoretical plates.The purity was checked with the aid of melting curves determined in a microcalorimeter and proved to be 96.6% or better.Refractive indices were determined and can be represented byequation imagewith an accuracy of 5 units in the fifth decimal place (c = number of carbon chain atoms).Densities, accurate to 1 unit in the fourth decimal place, can be represented byequation imageBoiling points can be given byb.pt. 20 mmequation imagefor the methyl esters (c> 5), accurate to 0.1 °.From our data, combined with literature values, the molecular refractivity of the CH2group in an aliphatic chain calculated according toLorentz‐Lorenz.was determined at 4.64 at room temperature.In addition, melting and transition points, and heats of fusion and transition were determined.
Oscilloscopic determination of the double layer capacity of mercury in 1 M HClO4 at high potentials by means of sine wave current
Authors: Sluyters J. H. , de Leeuwe R. 
Published: September 2010

AbstractA simple procedure is described by which the double layer capacity of mercury can be determined at potentials where the Hg/Hg2++ redox couple interferes with the direct mode of double layer capacity measurements. The results agree with those obtained recently with a different methodM. Sluyters‐Rehbach and J. H. Sluyters, Rec. Trav. Chim. 83, 217 (1964).
.
Chemistry of α‐diazosulfones: Part III. A simple preparation of N‐(sulfonylmethyl)urethanes by a Mannich condensation
Authors: Engberts J. B. F. N. , Strating J. 
Published: September 2010

AbstractN‐(Sulfonylmethyl)urethanes, which are important intermediates in the synthesis of α‐diazosulfones, have been prepared in reasonable yields by a Mannich condensation of a sulfinic acid, formaldehyde and ethyl carbamate.
The influence of steric and electronic factors on acidity. II. Cis‐ and trans‐3‐endo‐arylsulfonylbicyclo [2,2,1]hept‐5‐ene‐2‐carboxylic acids. Intramolecular field effect
Authors: Hogeveen H. 
Published: September 2010

AbstractThe apparent acidity constants of cis‐ and trans‐3‐endo‐arylsulfonylbicyclo‐[2,2,1]hept‐5‐ene‐2‐carboxylic acids, with aryl = p‐CH3OC6H4‐‐, p‐CH3C6H4‐, C6H5‐, p‐ClC6H4‐, m‐NO2C6H4‐ and p‐NO2C6H4‐, have been measured in 50% (by vol.) aqueous ethanol at 25°. The acidities of cis‐compounds are much lower than those of trans‐isomers, which is most likely due to an intramolecular field effect between the sulfonyl‐oxygens and the carboxylic anion in the cis‐compounds. The data in both series follow the Hammett equation with excellent fit and the values for the reaction constant δ are 0.351 (trans‐series) and 0.418 (cis‐series. This indicates that the magnitude of the field effect is virtually independent of substitution in the phenyl ring.
Studies in IVth group organometallic chemistry XVII: The exchange of butyl groups and chlorine atoms between tin and germanium
Authors: Luijten J. G. A. , Rijkens F. 
Published: September 2010

AbstractOne butyl group is exchanged for chlorine when tetrabutyltin and germanium tetrachloride or tin tetrachloride and tetrabutylgermane, respectively, are heated at 200° without a catalyst. The first of these reactions may be used in the preparation of butyltrichlorogermane.
Saturated five membered heterocyclics, II: Preparation of 1,3,4‐oxadiazolidines
Authors: Zwanenburg B. , Weening W. E. , Strating J. 
Published: September 2010

Abstract2,3,4,5‐Alkyl substituted 1,3,4‐oxadiazolidines are prepared in good yields by reaction of a symm.dialkylhydrazine and an aliphatic aldehyde. Two alternate mechanisms of the reaction are discussed. The N.M.R. spectra could be analysed taking into account the possible stereochemical configurations.
Reactivities of Csec‐H bonds towards chlorine in some alkanes and alkane carbochlorides
Authors: Smit P. , den Hertog H. J. 
Published: September 2010

AbstractPhotochlorinations of some alkanes (C5‐C7) and alkane carbochlorides (C3‐C6 and C8) in the liquid phase have been investigated, in the absence and in the presence of benzene, a solvent enhancing the selectivity of the reagent.It was found that whereas the Cω‐1‐H bonds are the most reactive ones in nearly all photochlorinations, the Cω‐2‐H bonds are attacked preferentially when chlorinating octanoyl chloride and the alkanes C5‐C7 in benzene.
Acid anilides: X. The analysis of ω‐phenylalkanoic acids by chromatography of the free acids and their anilides
Authors: de Jonge A. P. , Verhage A. , van der Ven B. 
Published: September 2010

AbstractPaper‐chromatographic separation of ω‐phenylalkanoic acid anilides is discussed and compared with the separation of free acids by other methods. Combination of both separation methods affords a means of identification which has been designated as pseudo two‐dimensional chromatography. Preparation of the anilides and the ultra‐violet spectra of both acids and anilides are described.
The constitution of the Grignard reagent: Part III, Conductivity of some ethylmagnesium compounds
Authors: Vreugdenhil A. D. , Blomberg C. 
Published: September 2010

AbstractElectrical conductivities of the Grignard reagent ‐ prepared from ethyl bromide and magnesium ‐, diethylmagnesium and mixtures of diethylmagnesium and magnesium bromide, all dissolved in diethyl ether have been measured in the concentration range 0.05‐3.0 molar at 25°. Significant differences between the conductances of a solution of the Grignard reagent and an equivalent solution of a mixture of diethylmagnesium and magnesium bromide were found only at concentrations up to 0.4 molar.
Synthesis of 3‐tert‐aminothiophens and their tetrahydro derivatives via enamines
Authors: Buiter F. A. , Weiland J. H. Sperna , Wynberg Hans 
Published: September 2010

AbstractAromatization of 3‐ketotetrahydrothiophen enamines (II) furnishes 3‐dialkyl‐aminothiophens (III). Reduction of the enamines with formic acid yields the tetrahydro derivatives (V). These compounds represent the first examples of simple 3‐tert‐amino‐thiophens and ‐tetrahydrothiophens.
Studies on vitamin d and related compounds. XVIII: An investigation into the interconversion of precalciferol and calciferol and of analogous compounds
Authors: Schlatmann J. L. M. A. , Pot J. , Havinga E. 
Published: September 2010

AbstractTwo simple calciferol analogues (1) having no five‐membered (D) ring fused to the C ring, show the same smooth thermal isomerisation to the corresponding precalciferol analogues as calciferol itself. The kinetics of this reaction have been studied; the activation energy and entropy were found to be 21.6 (± 0.2) kcal/mole and −17.2 e.u., respectively. The insensitivity of the reaction towards even rather drastic changes in the conditions is striking and the reaction mechanism formerly given10, 15 for the vitamin D ⇆ previtamin D interconversion seems to remain an attractive working hypothesis.There is one difference between the analogues and the calciferol system itself; in the former the equilibrium is far more on the “precalciferol” side. It is argued that this difference (and perhaps also the relative long wavelength ultra‐violet absorption of precalciferol) may be due to a strain in the precalciferol molecule originating from the presence of the C8‐C9 double bond in combination with the trans fused five‐membered ring. In agreement herewith, 13α‐precalciferol analogues having the five‐membered ring cis‐bonded and lacking this strain, are found to show a position of the equilibrium (and an ultra‐violet absorption) similar to that of the analogue II and different from that of precalciferol.
Chemistry of acetylenic ethers 74: 1‐(dialkylamino)‐1‐alkynes from 1‐alkoxy‐1‐alkynes
Authors: Montijn P. P. , Harryvan E. , Brandsma L. 
Published: September 2010

Abstract1‐Alkynyl ethers, RCC‐O‐Alk (with R  alkyl), have been converted into the corresponding yneamines, RCC‐N‐(R′)2, in good yields (except when R  CH3) by means of lithium dialkylamides, LiN‐(R′)2.
The interaction of transition metal ions and hydroxymethyl radicals during the radiolysis of methanol
Authors: Brackman W. , van de Craats F. , Smit P. J. 
Published: September 2010

AbstractCertain metal ions, in particular Co2+, Ni2+ and Cu2+ were found to increase the yield of formaldehyde at the expense of glycol during the radiolysis of methanol. The activities of the divalent first‐row transition metal ions correlate strikingly with the effect of these metal ions upon the quenching of triplet anthracene as measured by Linschitz and Pekkarinen.Both effects are ascribed to rapid complex formation between the metal ions and the· CH2OH radicals or triplet anthracene.
Diuretics II: 3‐Amino‐6‐chloro‐7‐sulfamoyl‐1,2,4‐benzotriazine 1‐oxide
Authors: Dolman H. , Peperkamp H. A. , Moed H. D. 
Published: September 2010

AbstractThe synthesis of 3‐amino‐6‐chloro‐7‐sulfamoyl‐1,2,4‐benzotriazine 1‐oxide (IIc) is described. This structural congener of the diuretic chlorothiazide (I) did not exhibit any diuretic activity.
Chemistry of acetylenic ethers 75: Isomerization of some 2‐alkynyl ethers into allenyl ethers with a note on the preparation of branched acetylenes
Authors: van Boom J. H. , Montijn P. P. , Brandsma L. , Arens J. F. 
Published: September 2010

Abstract2‐Alkynyl ethers of the types R′R″CH‐CC‐CH2OC2H5and R′R″R″′C‐CC‐CH2OC2H5(in which R′, R″ and R″′ are alkyl groups) have been converted by means of sodamide in liquid ammonia, in 70‐95% yields, into the allenyl ethers R′R″CH  C  CH‐OC2H5and R′R″R″′C‐CH  C  CH‐OC2H5.Acid hydrolysis of the allenyl ethers afforded thetrans‐α,β‐unsaturatedmagnified image.
The constitution of the Grignard Reagent: Part IV. The influence of oxygen on the number of individual particles in solutions of ethylmagnesium compounds
Authors: Vreugdenhil A. D. , Blomberg C. 
Published: September 2010

AbstractThe influence of oxygen on the number of individual particles in 10−3 · 10−2 molar diethyl ether solutions of ethylmagnesium bromide, diethylmagnesium, magnesium bromide and a mixture of diethylmagnesium and magnesium bromide was investigated. The ethoxide formed from the ethylmagnesium compounds is present as a trimer.
Titration of cerium (IV) sulfate with sodium oxalate at room temperature, using nitroferroin as indicator
Authors: Rao K. Bhaskara 
Published: September 2010

AbstractA new convenient procedure is reported for the titration of ceric sulfate with sodium oxalate at room temperature. The procedure consists in the titration of ceric sulfate with sodium oxalate in about 0.5 N nitric, perchloric, or hydrochloric acid media, using nitroferroin as indicator.
Sur les Ethers β‐Diéthylaminoéthyliques des Derives du Biphényle et Leurs Propriétés Pharmacodynamiques
Authors: Petit M. L. , Gouot Mll E. J. , Luczak Mme J. 
Published: September 2010

AbstractOn a synthétisé un certain nombre d'éthers β‐diéthylaminoéthyliques des p‐hydroxybiphényle, chloro‐3 hydroxy‐2 biphényle, bromo‐5 hydroxy‐4 biphényle et dihydroxy‐2‐2′ biphényle, afin d'examiner certaines des propriétés pharmacodynamiques des substances ainsi obtenues. Les éthers possèdent une bonne activité spasmolytique et sont comparables à la quinidine et à la papavérine.
Racemization and bifunctional catalysts in peptide synthesis
Authors: Beyerman H. C. , van Den Brink W. Maassen , Weygand F. , Prox A. , König W. , Schmidhammer L. , Nintz E. 
Published: September 2010

AbstractThe influence was examined of representative bifunctional catalysts on racemization in peptide syntheses via aminolysis of cyanomethyl, p‐nitrophenyl, thiophenyl, and vinyl esters. Three different tests were used, based on gravimetric, polarimetric, and gas‐liquid chromatographic analysis, respectively. 1,2,4‐Triazole, which was investigated most extensively, did not cause racemization in any of the couplings.Imidazole, which has also been recommended for acceleration of peptide syntheses, led to racemization in several cases.The structure of N‐acyl derivatives of 1,2,3‐ and 1,2,4‐triazole was determined by proton resonance measurements.
The conformation of bicyclo[3.3.1]nonane
Authors: Laszlo Ilona 
Published: September 2010

AbstractX‐ray powder diagrams of bicyclo[3.3.1]nonane I) showed that the pure compound crystallizes in the face centered cubic lattice with a cell parameter of 9.57 Å. Phase diagrams and X‐ray diagrams of binary mixtures of (I
) and adamantane indicate that the conformation of bicyclo[3.3.1]nonane is that of a slightly distorted chair‐chair form.
Interaction of electron acceptors with bases part 14: Solvent effect on the optical transition of organic charge‐transfer complexes
Authors: Emslie P. H. , Foster R. 
Published: September 2010

AbstractThe energies of the optical transitions for “non‐ionic” organic charge‐transfer complexes in a range of solvents have been measured. The solvents may be divided into those which can achieve an effective solvent cage and those which cannot. For the former class the Franck‐Condon principle applied to solvent re‐orientation results in a hypsochromic shift with increasing ionising ability of the solvent. For the latter class, which may be described as inert solvents, where there is no solvent cage, the dispersion forces and polarisation of the solvent cause bathochromic shifts as the ionising ability of the solvent increases.
Fluid phase equilibria in the system polyethene‐ethene
Authors: Swelheim T. , De Swaan Arons J. , Diepen G. A. M. 
Published: September 2010

AbstractThe system polyethene ‐ ethene has been investigated in a high‐pressure autoclave in a temperature region of 100‐140° up to pressures of 2000 kg/cm2. Pressure‐temperature (P‐T) data were taken for the curve separating the homogeneous fluid phase region from the fluid two‐phase region for mixtures with polyethene‐compositions up to 30% by weight.
Spectroscopic investigations of thiobenzophenones: II. Electronic spectra. Correlation of Substituent Effects on the Arylthiocarbonyl Absorption Maximum with substituent parameters
Authors: Korver O. , Veenland J. U. , de Boer Th. J. 
Published: September 2010

AbstractIn ortho‐methylthiobenzophenone the unsubstituted phenyl group is nearly coplanar with the thiocarbonyl group, whereas the o‐tolyl group is not.The phenylthiocarbonyl absorption band shifts upon introduction of meta‐and para‐ substituents according to various σ‐values. A similar quantitative correlation exists for the intensities.
Spectroscopic investigations of thiobenzophenones: III. Infra‐red absorption and nuclear magnetic resonance spectra of thiobenzophenones
Authors: Korver O. , Veenland J. U. , de Boer Th. J. 
Published: September 2010

AbstractThe shifts in the CS stretching vibration caused by various substituents in thiobenzophenone are so small that no good correlations between substituent constants and absorption frequencies is found.Differences between the n.m.r. spectra of thiobenzophenones and benzophenones can be explained with the aid of conformations deduced from the electronic spectra.
Investigations on pyrazine derivatives IX: On the effect of hydrogen peroxide on 5,6‐diphenyl‐2,3‐dihydropyrazine
Authors: Mager H. I. X. , Berends W. 
Published: September 2010

AbstractThe effect of hydrogen peroxide on 5,6‐diphenyl‐2,3‐dihydropyrazine has been studied. Several reactions take place which might be considered as models for some of the spontaneous conversions shown by partially reduced pyrazines on exposure to air. In no case was 5,6‐diphenyl‐2,3‐dihydropyrazine 1,4‐di‐N‐oxide formed, but products of ring‐opening: N/N′‐dibenzoylethylenediamine, and N‐benzoylethylenediamine, and a product of a most interesting ring‐contraction: 2‐phenyl‐2‐imidazoline. In addition some 2,3‐diphenylpyrazine could be isolated. Reaction mechanisms have been postulated; the primary product of oxidation has been formulated as 5,6‐diphenyl‐1,2,3,6‐tetrahydro‐pyrazine 6‐hydroperoxide.Tetrahydropyrazine hydroperoxides may also be formed spontaneously, for example, after catalytical hydrogenation, if tetrahydropyrazines are exposed to air. The results described in this paper seem also to be of some importance in the fields of condensed pyrazines like quinoxalines, pteridines, iso‐alloxazines and, moreover, they contain principles for new syntheses of 2‐imidazolines.
Studies in homogeneous catalysis: Kinetics and mechanism of the copper‐catalysed reaction of nitric oxide and diethylamine (I)
Authors: Brackman W. , Smit P. J. 
Published: September 2010

AbstractA study has been made of the copper‐catalysed reaction of NO with diethylamine, which at 30° yields nitrosodiethylamine and N2O. A mechanism is proposed in which the cupric ion in combination with NO functions as the nitrosating agent for the amine. The cuprous complex formed in this reaction is rapidly reoxidized by the adduct of diethylamine and NO, (C2H5)2NH2+ · (C2H5)2N · (NO)O−, which yields the fragments NO− (or NOH) and (C2H5)2N · NO−. The radical‐anion reacts with NO to regenerate the original adduct while NOH yields nitrous oxide and water.
Acid anilides: XI. synthesis, ultra‐violet spectra and paper chromatography of 2‐alkenanilides and 2,4‐alkadienanilides
Authors: de Jonge A. P. , Schogt J. C. M. , de Bruijn J. , Verhage A. 
Published: September 2010

AbstractThe anilides of some 2‐alkenoic and 2,4‐alkadienoic acids were prepared, their ultra‐violet spectra recorded, and their paper‐chromatographic behaviour compared to that of alkananilides.
A solvent‐extraction study of the dissociation of aniline sulfate
Authors: Aboul‐Seoud A. , Doheim M. 
Published: September 2010

AbstractThe distribution of aniline betweenn‐heptane and aqueous ammonium sulfate solutions was studied at different temperatures. The activity coefficients of aniline in aqueous ammonium sulfate solutions, were determined.The effect of ammonium sulfate on the dissociation of aniline sulfate was studied, at different amine salt concentrations, and different temperatures, using a modified distribution method1. ΔH, ΔS and ΔF for the dissociation of the anilinium ion, were determined.
Investigations on sterols XXVI: Synthesis and properties of 6‐substituted 9β,10α‐steroids
Authors: Westerhof P. , Hartog J. , Halkes S. J. 
Published: September 2010

AbstractThe synthesis and properties are described of some 6‐halo‐9β,10α‐pregnane and 6‐halo‐9β,10α‐androstane derivatives containing the 4‐en‐3‐one system. Halogenation at position 6 is accomplished by reaction of the 3‐acetoxy‐3,5‐dienes with perchloryl fluoride, chlorine, bromine or N‐bromosuccinimide. At the fluorination 6‐hydroxy compounds are obtained as by‐products, the structures of which are proved by alternative synthesis and by conversion into related compounds. The spectral data are discussed in connection with the structural assignments of the 6‐substituents. The biological results are summarized.
Investigations on sterols XXIX: Synthesis and properties of some 6,7‐dehydro‐9β,10α‐steroids
Authors: Westerhof P. , Hartog J. 
Published: September 2010

AbstractAlternative methods are described for the synthesis of a number of 6‐halo‐9β,10α‐pregnane and 6‐halo‐9β,10α‐androstane derivatives having a 4,6‐dien‐3‐one or a 1,4,6‐trien‐3‐one system. 4‐Halo and 6‐methoxy‐4,6‐dien‐3‐ones have been prepared, too. The endocrinological results are summarized.
Bromination of methylpyridines in fuming sulfuric acid
Authors: van der Does L. , den Hertog H. J. 
Published: September 2010

AbstractBrominations of the isomeric methylpyridines and 2,6‐dimethylpyridine in fuming sulfuric acid have been studied.It was found that in this medium at moderate temperatures bromo derivatives substituted in the pyridine nucleus are formed in excellent yields as sole reaction products.Some of these bromination reactions are satisfactory as synthetic methods.