bluuebunny/crossref_metadata_2025_split huggingface dataset:
Chemical shifts of ethylenic protons in CIS and TRANS β‐Arylthio‐, β‐arylsulfinyl‐and β‐arylsulfonyl‐acrylic acids
Authors: Hogeveen H. , Maccagnani G. , Taddei F. 
Published: September 2010

AbstractChemical shifts of the ethylenic protons Hα and Hβ in cis and trans β‐arylthio‐,β‐arylsulfinyl‐ and β‐arylsulfonyl‐acrylic acids have been determined in acetone and in Na2CO3/D2O solution. The absorption signals were assigned unambiguously by β‐deuteration. An increase of electron‐withdrawing power of the β‐substituent (ArSO2 > ArSO > ArS) causes an increase in shielding of Hβ proton and a decrease in that of Hα proton. The τ‐values of the Hβ protons are lower in the trans than in the corresponding cis acids, which may be explained in terms of magnetic anisotropy effects of the carboxyl group in the trans acids. Generally, the τ‐values of the Hβ protons are lower, and those of the Hα protons higher, in acetone than in Na2CO3/D2O solution; this is probably due to differences in electron‐withdrawing power of the COOH and COO⊙ groups. In all trans derivatives the average values of the coupling constants Jαβ are 15.3 c./sec., and lie between 10.1‐11.4 c./sec. for the cis derivatives. The effects of para‐substituents (CH3O, CH3, H, Cl, NO2) on the chemical shifts of the Hα and Hβ protons in cis and trans β‐arylthio‐, β‐arylsulfinyl‐, and β‐arylsulfonyl‐acrylic acids are correlated with the Hammett σ‐constants.
On the impedance of galvanic cells: XI. The impedance of the Hg/Hg2++ electrode in 1 M and 0.1 M HClO4
Authors: Sluyters‐Rehbach M. , Sluyters J. H. 
Published: September 2010

AbstractThe accuracy of the double layer capacity measurements at high potentials described in part IX 1 is critically examined, especially with a view to the correct determination of the ohmic resistance of the cell. A limit for the exchange current density of the redox couple, which can be detected by the method of frequency variation, is determined. The systematic error in the calculated double layer capacity values, if this limit is just reached, is estimated. From impedance measurements in 0.1 M‐HClO4 solution it appears that the capacity‐potential curve is identical with that in 1 M‐HClO4 solution.
Detection of γ‐ and δ‐keto acids in butterfat
Authors: van der Ven B. 
Published: September 2010

AbstractA mixture of keto acids (other then β) in an amount of about 100 p.p.m. has been isolated from steam‐deodorized butterfat by means of Girard‐T‐reagent. The methylated keto acids were fractionated and after saponification, the lower boiling fraction was reduced with sodium tetrahydridoborate. After heating of the hydroxy acids obtained, a small amount (about 2.5. p.p.m.) of γ‐ and δ‐lactones could be isolated. G.L.C.‐analysis demonstrated that the main components were δ‐octa, δ‐deca, δ‐dodecalactones and the minor components γ‐deca, γ‐undeca and γ‐dodecalactones, thus proving the presence of the corresponding keto acids in butterfat.
The reaction of hydroxy‐esters and amino‐esters with isocyanates
Authors: Rekker R. F. , Nauta W. Th. 
Published: September 2010

AbstractAddition of an organic isocyanate to hydroxy‐esters or amino‐esters results in attachment of the active H of the OH or NH2 group to the N atom of the isocyanate, the rest of the adding molecule being linked to the C atom of the N = C bond. Though stable in themselves, the resulting products undergo cyclisation in inert media under the catalytic influence of sodium, or in some cases, by simply heating without any medium. The final ring compounds obtained in this way are oxazolidinediones, hydantoins, oxazines, uracils and quinazolidinediones starting with α‐hydroxy‐esters, α‐amino‐esters, ortho‐hydroxybenzoates, β‐amino‐esters, and ortho‐aminobenzoates, respectively, as the original addition partners. β‐Hydroxy‐esters with a free H in the α‐position give unsaturated amides as final reaction products.
Substituierte Amide des Cystins als Inhibitoren des Oxytocinabbaues durch die Oxytocinase des Schwangerenserums
Authors: Wintersberger E. , Stoklaska E. , Moed H. D. , van Dijk Und J. 
Published: September 2010

AbstractDie Synthesen einiger einfach gebauter substituierter Cystinylamide werden beschrieben. Die durch diese Substanzen verursachte Hemmung des Abbaues von L‐Cystin‐di‐β‐naphthylamid und von Oxytocin durch die Oxytocinase des Schwangerenserums wird bestimmt und diskutiert.
Asymmetric syntheses by Grignard compounds prepared in optically active solvents: Part I. Optically active monofunctional ethers
Authors: Blomberg C. , Coops J. 
Published: September 2010

AbstractGrignard compounds, prepared in benzene in the presence of one molar equivalent of an ether derived from (‐) (S)‐2‐methylbutan‐1‐ol, yield optically active alcohols on reaction with aldehydes. A comparison is made with the optical activities of the products obtained when an optically active bifunctional ether ((+) (2 R:3 R)‐2,3‐dimethoxybutane) is used. A discussion is given of the reacting system.
Bicyclanes: V. New syntheses of cis‐bicyclo[3.3.0]octane and cis‐bicyclo[3.3.0]oct‐2‐ene
Authors: Knotnerus J. , Schilling H. 
Published: September 2010

AbstractNew three‐step syntheses of cis‐bicyclo[3.3.0]octane and cis‐bicyclo[3.3.0]oct‐2‐ene are described; overall yields of about 20% based on cyclopentadiene are obtained.
3,4‐Dihydro‐4‐hydroxy‐1,3‐benzoxazin‐2‐one derivatives
Authors: Strube R. E. , Mackellar F. A. 
Published: September 2010

AbstractA general method is described for synthesizing compounds of structure exemplified by A, from methyl isocyanate and 2‐hydroxybenzaldehyde in the magnified imagepresence of a basic catalyst (triethylamine).The reaction product of phenyl isocyanate and 2‐hydroxybenzaldehyde in the presence of triethylamine is 3,4‐dihydro‐3‐phenyl‐4(phenylcarbamoyloxy)‐2H‐1,3‐benzoxazin‐2‐one (structure B).Evidence for the proposed structures is presented based on chemical and spectral properties.
A thermodynamic study of the dissociation of o‐chloroaniline hydrochloride
Authors: Aboul‐Seoud A. , El‐Hares M. 
Published: September 2010

AbstractFrom the study of the distribution of o‐chloroaniline between petroleum ether and aqueous solutions of sodium chloride, at 5, 15, 25 and 35°, the activity coefficients of the free amine, under these conditions, were calculated.The dissociation constant of o‐chloroaniline hydrochloride was determined under the same conditions using the distribution method. The ratio of the activity coefficients of hydrogen and o‐chloroanilinium ions was calculated for each case. The relationship between pK and salt molality was studied.
Mixed carboxylic acid anhydrides: II. Esterification of alcohols with the formic acid/acetic anhydride reaction mixture
Authors: Stevens W. , van Es A. 
Published: September 2010

AbstractThe investigations of Béhal and other authors (loc. cit.) have led to the generally accepted view that the esterification of alcohols with the formic acid/acetic anhydride reaction mixture leads to the exclusive formation of formates. A reinvestigation, however, has shown that under the conditions used by Béhal, acetates are also produced. Generally, the amounts of acetates formed decrease in the order primary, secondary, tertiary alcohols; in the last case acetates are formed to a negligible degree. This finding leads to a simple and convenient method for the preparation of pure tertiary alkyl formates in high yields. The results obtained are discussed in relation to conflicting literature data as regards the synthesis of formates.
Triethynyl‐phosphine, ‐arsine and ‐stibine
Authors: Voskuil W. , Arens J. F. 
Published: September 2010

AbstractThe compounds M(CCH)3, with MP, As and Sb, are prepared from the appropriate trichlorides and ethynylmagnesium bromide in tetrahydrofuran. All three compounds are relatively stable volatile solids at room temperature, but detonate violently by strong friction. Infrared and proton magnetic resonance data are given.
The system 2,6‐dichloro‐p‐benzoquinone‐N,N,N′,N′‐tetramethyl‐p‐phenylenediamine in acetonitrile: Short communication
Authors: Emslie P. H. , Foster R. , Thomson T. J. 
Published: September 2010

AbstractThe slow disappearance of the charge‐transfer complex and the slow increase in concentration of the Wurster free radical ion in solutions formed by dissolving 2,6‐dichloro‐p‐benzoquinone and N,N,N′,N′‐tetramethyl‐p‐phenylenediamine in acetonitrile have been shown to be the result of the upset of equilibria between these species due to the further reaction of the semiquinone ion formed from the quinone.
Spectroscopic investigations of olefinic compounds: Part I. Rehybridization as a concept for the counterbalance of sterical hindrance and ring strain
Authors: Rummens F. H. A. 
Published: September 2010

AbstractRehybridization as a possible means to alleviate the effects of sterical hindrance and ringstrain has been investigated. This concept, although general in nature, has been analysed in detail for ethylenic structures. It is shown that two out of the six fundamental distortions of a magnified image “molecule” can be counter‐balanced by rehybridization. One of these, the in‐plane rehybridization of the sp2 hybrid orbitals, seems to be the most useful mechanism. For small distortions the change in p character (as given by its mixing coefficient λk) for each of these sp2 orbits depends only on the change in bond angle (ΘY) opposite to the (k) hybrid orbital. It is shown that Δλk = √6ΔΘY.The theory allows the prediction of infrared frequency shifts for the  C‐H stretching, C  C stretching, C  C‐H in‐plane deformation, and C  C‐H out‐of‐plane deformation vibrations as a function of sterical hindrance. A comparison of the infrared spectra of a large variety of ethylenic hydrocarbons reveals a very satisfactory agreement between observed and predicted shifts.
The synthesis of arylsulfonyl halides
Authors: Prinsen A. J. , Cerfontain H. 
Published: September 2010

AbstractThe synthesis of a series of arylsulfonyl chlorides by a modification of the Sandmeyer reaction as developed by Meerwein et al1 is described. This method seems applicable to the preparation of arylsulfonyl bromides, but not for arylsulfonyl fluorides. The characteristic IR vibrations of the SO2‐group are tabulated for the various arylsulfonyl halides.
Tetrakis(triphenylplumbyl)methane and two other triphenylplumbyl‐substituted methanes: (Preliminary communication)
Authors: Willemsens L. C. , van Der Kerk G. J. M. 
Published: September 2010

AbstractThe title products can be prepared readily from triphenylplumbyl‐lithium and carbon tetrachloride, chloroform or methylene chloride. The existence of (Ph3Pb)4C is remarkable from a stereochemical point of view.
Hetarynes IX: Reactions of some bromoethoxypyridines with lithium piperidide in piperidine
Authors: van Der Plas H. C. , Hijwegen T. , Den Hertog H. J. 
Published: September 2010

AbstractReactions of 3‐bromo‐4‐ethoxypyridine and 2‐bromo‐6‐ethoxypyridine with lithium piperidide in piperidine have been investigated.It was found that in these compounds both substituents when occupying positions 2,4 or 6 are replaced by the piperidino group without rearrangements occurring. From 3‐bromo‐4‐ethoxypyridine some 2,4‐dipiperidinopyridine is formed as an additional product, probably via 4‐piperidino‐2,3‐pyridyne as an intermediate.
Volumetric estimation of chromium (VI) and vanadium (V) in mixtures
Authors: Rao K. Bhaskara , Rao Devaraj 
Published: September 2010

AbstractA rapid and convenient volumetric method is reported for the estimation of chromium (VI) and vanadium (V) in mixtures. The procedure consists in the estimation of (1) chromium plus vanadium in the mixture by titration of the mixture in about 0.25 N sulfuric acid containing 5 ml of phosphoric acid and 1 ml of 0.1% barium diphenylamine sulfonate with ferrous ammonium sulfate to the exact end‐point; (2) vanadium in the mixture by titration of the solution, left after the first titration, with permanganate, using ferroin as indicator, and (3) chromium in the mixture by calculation from the difference of the two values.
An electron diffraction study of selenium trioxide
Authors: Mijlhoff F. C. 
Published: September 2010

AbstractBy electron diffraction it has been found that selenium trioxide vapour contains tetrameric ring molecules dissociated to the extent of about 30% into monomer at 120°. Principal distances are: in the monomer: Se‐O, 1.69 Å; in the tetramer: Se‐bridging O, 1.80 Å; Se‐non bridging O, 1.56 Å.
Vapour pressures and their estimation
Authors: Mcgowan J. C. 
Published: September 2010

AbstractIt is proposed that for liquid unassociated compounds well below their critical temperaturesLog p/pb) = Log Vg/VL)b

where p and pb are vapour pressures at the absolute temperature T and at the boiling point Tb respectively; Vg and VL are the molecular volumes of the compound in the vapour and liquid phases (the figures here referring to the boiling point); and n is a constant for a given compound. For monatomic gases n is one and for higher members of homologous series it is about two. For many substances, n can be taken as 1.7 and log10 (Vg/VL)b as 2.7: the equation with these values may be used to estimate vapour pressures of unassociated compounds. Moreover, for very similar compounds Tbn is proportional to the parachor.
The reaction of carbon suboxide with diazomethane
Authors: Schaafsma S. E. , Steinberg H. , De Boer T. H. J. 
Published: September 2010

AbstractMethyl malonate (A), methyl succinate (B), methyl glutarate (C) and methyl 3‐oxocyclobutanecarboxylate (D) are formed from diazomethane and carbon suboxide in the presence of methanol. A mechanism is proposed for this reaction.
Chemistry of α‐diazosulfones: Part V. The synthesis of arylsulfonyldiazomethanes and alkylsulfonyldiazomethanes
Authors: van Leusen A. M. , Strating J. 
Published: September 2010

AbstractN‐(Sulfonylmethyl)urethanes, described in the preceding paper1, are converted into N‐nitroso derivatives, RSO2CH2N(NO)CO2C2H5, which are transformed into α‐diazosulfones, RSO2CHN2, by a heterogeneous reaction on alumina. Reaction of α‐diazosulfones with hydrochloric acid leads to α‐chlorosulfones, and with triphenylphosphine to so‐called phosphazines, RSO2CH = N ‐ N = P(C6H5)3. The IR and NMR spectra of α‐diazosulfones are discussed.
Thermal decomposition of chloroform in the presence of olefins
Authors: Engelsma J. W. 
Published: September 2010

AbstractThe gas‐phase decomposition of chloroform at 400‐500°C in the presence of an alkene leads to a chlorodiene and hydrogen chloride.Evidence is presented that the primary step is the decomposition of chloroform to dichlorocarbene, which adds to the alkene; the resulting dichlorocyclopropane rearranges, with loss of hydrogen chloride, to a chlorodiene.
The chemistry of cycloheptatriene: Part XI: A further study of transannular 1‐5 shifts of hydrogen in phenylcycloheptatrienes
Authors: Ter Borg A. P. , Kloosterziel H. 
Published: September 2010

AbstractThe rate of the interconversion of 2‐ and 1‐phenylcycloheptatriene upon heating has been measured. These 1‐5 shifts ‐ in which the phenyl group is attached to the non‐shifting double bond — are somewhat faster than in unsubstituted cycloheptatriene.
Spectroscopic investigations of thiobenzophenones: I. Electronic spectra
Authors: Korver O. , Veenland J. U. , de Boer Th. J. 
Published: September 2010

AbstractThe effect of substituents on the geometry of thiobenzophenones is derived from the arylthiocarbonyl U.V.‐absorption at 300‐375 nm.Hammettσ‐constants can be correlated with the energy of the n→π* transition of the thiocarbonyl group near 600 nm. Absorption at 230 nm can be ascribed partly to aryl‐aryl interaction by comparison with substituted diarylethylenes.
Fatty acid synthesis in dairy cattle with experimental ketosis
Authors: Elema J. 
Published: September 2010

AbstractThe incorporation of acetate‐α‐14C in the liver higher fatty acids of normal and ketotic cows has been studied.In vitro incubations with liver slices, obtained by biopsy, showed an inhibited synthesis of these acids in ketotic livers compared with that in normal livers. The inhibition ranged from 18% to 72% in accordance with the intensity of the ketosis.
Studies in homogeneous catalysis: The competitive formation of alkyl nitrite and nitrosamine in the reaction of NO with diethylamine‐alcohol mixtures (II)
Authors: Brackman W. , Smit P. J. 
Published: September 2010

AbstractThe copper‐catalysed reaction of nitric oxide with diethylamine in alcoholic solvents at 30° and 1 atm yields nitrosamine as the sole nitrosation product. At lower reaction temperatures, e.g.−30° nitrosamine is formed only in low yields and alkyl nitrite, derived from the alcohol, is obtained instead.The mechanism controlling the relative formations of the two products has been studied. It is demonstrated that the decisive factor is not primarily the temperature, but rather the NO‐concentration in solution. Arguments are presented for the view that the reductive splitting of the adduct R2N·N(NO)O− by cuprous ion is conditioned by the presence of a proton donor (here the alcohol) which must be coordinated with the cuprous ion (eq. 7‐10). The cupric alkoxide complex which is formed in this reaction and which is not in equilibrium with the amine‐alcohol system gives rise, at sufficiently high NO‐concentrations, to the formation of alkyl nitrite.
A spiro Meisenheimer compound
Authors: Foster R. , Fyfe C. A. , Morris J. W. 
Published: September 2010

AbstractA Meisenheimer compound has been prepared by the action of a base on 1‐(2′‐hydroxyethoxy)‐2,4,6‐trinitrobenzene. The structure contains a 1,3‐dioxolane ring linked to the six membered ring containing the pentadienate system by a common carbon atom.
Synthesis of β‐phenylethylamine derivatives IX: The enantiomers and diastereoisomers of N‐phenoxyalkyl‐β‐(4‐hydroxyphenyl)ethylamine derivatives
Authors: van Dijk J. , Keizer V. G. , Peelen J. F. , Moed H. D. 
Published: September 2010

AbstractThe investigation deals with the synthesis and configuration of the stereoisomers of a new class of sympathomimetic amines: magnified image
Aromatic sulfonation XII: Kinetics of the sulfonation of p‐ and o‐toluenesulfonic acid in aqueous and fuming sulfuric acid
Authors: Cerfontain H. 
Published: September 2010

AbstractThe kinetics of the sulfonation of p‐ and o‐toluenesulfonic acid have been measured at 25.0° in aqueous and fuming sulfuric acid, the concentrations varying from 93.3‐103.3 wt‐% H2SO4. The reaction is first order with respect to the sulfonic acid.The observed variation in the apparent first order rate constants is of the order of 106. The sulfonation kinetics are shown to be consistent with the sulfonation mechanisms previously proposed for aqueous1 and fuming2 sulfuric acid. In aqueous sulfuric acid varying in composition from 93.3‐98.8 wt‐% H2SO4 isomerization was shown to be a reaction of minor importance.
Microbiological conversion of 19‐nortestosterone (VI) 1β‐hydroxylation
Authors: Bolt C. C. , Mijs W. J. , Zeelen F. J. , Szpilfogel S. A. , de Flines J. , van der Waard W. F. 
Published: September 2010

AbstractThe microbiological transformation of 19‐nortestosterone with Botryodiplodia malorum, leading to the 1β‐hydroxy‐derivative, is described.
The synthesis of 1‐arylisochromans and their use in the preparation of ortho‐substituted diphenylmethane derivatives
Authors: van der Stelt C. , Hofman P. S. , Nauta W. Th. 
Published: September 2010

AbstractSeveral 1‐arylisochromans were prepared from 1‐bromoisochroman and 1‐bromo‐4,4‐dimethylisochroman by reaction with arylmagnesium bromides. Bromination and heating yielded, presumably via bromo‐1‐arylisochromans, o‐(bromoalkyl)benzophenones. Treatment with lithium aluminium hydride converted the ketones into the corresponding carbinols, the side‐chain being simultaneously debrominated if sufficient hydride was used.Reactions of the bromoalkylbenzophenones with hydrazine derivatives yielded benzodiazepines.Treatment with hydriodic acid and red phosphorus converted 1‐phenyl‐isochroman into o‐(2‐iodoethyl)diphenylmethane while 4,4‐dimethyl‐1‐phenyl‐isochroman yielded 10,11‐dihydro‐10,10‐dimethyl‐5H‐dibenzo[a,d]cycloheptene and a compound (C13H10)n of unknown structure.
A simple synthesis of α,α,α‐trifluoro‐p‐toluic acid
Authors: van der Stelt C. , Nauta W. Th. 
Published: September 2010

AbstractThe inexpensive p‐chloro‐α,α,α‐trifluorotoluene proved a useful intermediate for the preparation of p‐trifluoromethylphenyl compounds because of its easy conversion (with cuprous cyanide in 1‐methyl‐2‐pyrrolidone at 240° in a closed vessel) into α,α,α‐trifluoro‐p‐tolunitrile and, subsequently, into α,α,α‐trifluoro‐p‐toluic acid.
Validity of Martin's equation in reversed‐phase paper‐chromatography
Authors: Peereboom J. W. Copius 
Published: September 2010

AbstractThe properties of the paper‐chromatographic system paraffin oil/acetic acid‐water (84 + 16), applied to the analysis of sterols, have been investigated.The variation of the cross sectional areas occupied by the stationary and mobile phases (AL/AS ratio) was studied. By inserting experimental values for AL/AS, RF and the partition coefficients of two sterols in the equation of Martin: α = AL/AS (1/RF ‐ 1), strong evidence was obtained as to the validity of this equation in the reversed‐phase system studied.
The pyrolysis of 2‐chloro‐1,3,2‐dioxaborolan
Authors: Finch Arthur , Hyams I. J. 
Published: September 2010

AbstractThe kinetics of liquid phase pyrolysis of 2‐chloro‐1,3,2‐dioxaborolan between 100° and 150° have been followed by spectrophotometric and titrimetric methods.
Photoconductivity spectra of stable and metastable single‐crystals of perylene
Authors: Mulder B. J. 
Published: September 2010

AbstractA study was made of the photoconductive properties of plate‐shaped single crystals of perylene with aqueous electrodes applied to both sides of the crystal. Two modifications have been investigated, a stable modification (α‐perylene) and a metastable one (β‐perylene). Photoconductivity spectra have been measured by illuminating through the positive electrode. The spectra of α and β‐crystals show analogous systems of vibronic bands with a wavelength shift of about 200 cm−1 between the two band systems. In the case of α‐crystals the conductivity spectrum duplicates the optical absorption spectrum. For β‐crystals the agreement between the conductivity spectrum and the reported absorption spectrum is less satisfactory.The shape of the photoconductivity spectra and various other evidence indicates that the origin of all observed photocurrents is at the surface of the crystal in contact with the positive electrode. Here excited perylene molecules react with the electrode to give a mobile charge carrier (hole). To account for the observed quantum yields of the photoconduction process it must be assumed that excitation energy can migrate (in the form of excitons) from the interior of the crystal to its surface (the same picture is generally accepted in the photoconduction of anthracene crystals). The quantum efficiencies obtained with β‐crystals were considerably higher than those for α‐crystals. This can be correlated with a difference in the mean diffusion paths of the excitons in the two modifications. The relatively short diffusion path in the dimeric α‐crystals is attributed to the formation of immobile charge‐transfer states.
On the impedance of galvanic cells: XII. The impedance and the admittance of a streaming mercury electrode; theoretical considerations
Authors: Ijzermans A. B. , Sluyters‐Rehbach M. , Sluyters J. H. 
Published: September 2010

AbstractExpressions for the complex impedance and admittance of a streaming mercury electrode in the presence of either an irreversible or a reversible redox system are derived. An irreversible redox couple gives rise to complex plane diagrams identical with those formerly derived for other electrodes (part I1, part III2). However, complex plane diagrams characteristic for the streaming mercury electrode occur in the case of a reversible redox system.Methods for obtaining information from the diagrams are indicated. The application of streaming mercury electrodes for the determination of kinetic parameters of electrode reactions does not seem very attractive.