bluuebunny/crossref_metadata_2025_split huggingface dataset:
Diperoxycarboxylic anhydrides and their urea adducts as peroxy acid precursors
Authors: Heslinga L. , Schwaiger W. 
Published: September 2010

AbstractUnbranched aliphatic diperoxycarboxylic acids of short chain length can be included in urea by acetylation in the presence of the latter compound. The reactions carried out with diperoxysuccinic, diperoxyadipic and diperoxyazelaic acid proceed almost quantitatively at room temperature. The diacetic diperoxycarboxylic anhydrides thus stabilized readily react with hydrogen peroxide in aqueous solution at room temperature, yielding mixtures of peroxyacetic and diperoxycarboxylic acid in high yield.Non‐included 3,3′‐dicarboxypropionyl and acetyl 3‐carboxypropionyl peroxide also form peroxy acids under these conditions. However, perhydrolysis of non‐included n‐acyl peroxides R‐C∥‐O‐O‐C‐R∥ is negligible.
The nature of the chemiluminescence of dicumyl peroxide decomposition
Authors: de Kock R. J. , Hol P. A. H. M. 
Published: September 2010

AbstractThe nature of the chemiluminescence phenomenon generally observed during oxidation of organic substances at elevated temperatures, was studied on the system dicumyl peroxide‐polypropylene. Arguments are put forward in favour of the assumption that the luminescence observed during decomposition of dicumyl peroxide, should be interpreted as phosphorescence of the reaction product acetophenone.
Synthesis of some poly‐unsaturated aldehydes
Authors: Ward J. P. , van Dorp D. A. 
Published: September 2010

AbstractPropargyl aldehyde diethyl acetal (1,1‐diethoxy‐2‐propyne) and 2,5‐hexadiynal diethyl acetal (1,1‐diethoxy‐2,5‐hexadiyne) have been successfully employed in the synthesis of the unsaturated aldehydes 2trans,5cis‐undecadienal, 2trans,5cis,8cis‐tetradecatrienal and 2trans,5cis,8cis, 11cis‐heptadecatetraenal, which were characterized as their 2,4‐dinitrophenylhydrazones.7‐Chloro‐1,1‐diethoxy‐2,5‐heptadiyne has been prepared and used in the synthesis of 2trans5cis,8cis‐tetradecatrienal.In addition, the syntheses of the 2,4‐dinitrophenylhydrazones of 2trans,6cis‐dodecadienal, 2trans,6cis,9cis‐pentadecatrienal and 2trans,6trans‐dodecadienal are described.
Determination of the absolute configuration of 3‐bromocamphor
Authors: Northolt M. G. , Palm J. H. 
Published: September 2010

AbstractThe absolute configuration of (+)‐3‐bromocamphor has been determined by X‐ray single crystal diffraction, Br acting as anomalous scatterer for MoKa radiation. The absolute configuration thus determined is in agreement with that proposed by Fredga and Miettinen4 on the basis of chemical evidence: in (+)‐camphor the “bridge” atom C(7) (connecting C(1) and C(4)) is behind the mean plane of the cyclohexane ring atoms, if the latter are numbered clockwise, and the oxo‐oxygen atom is situated at C(2).
Enthalpies of solution of some alkali halides in N‐methylformamide at 25°
Authors: Weeda L. , Somsen G. 
Published: September 2010

AbstractThe enthalpies of solution of LiI, NaI, KF, KCl, KBr, KI, RbI and CsI in anhydrous N‐methylformamide (NMF) at concentrations of about 5 × 10−3 molal have been measured with an adiabatic calorimeter. The enthalpies of dilution in NMF were calculated with the aid of the extended Debye‐Hückel theory. The differences in enthalpy of solution of the alkali iodides between (1) water and formamide and (2) water and NMF are compared with the results of van Eck's theory of ionic solvation.
The conformation of non‐aromatic ring compounds. XXII: The crystal structure of trans‐2,5‐dibromo‐1,4‐dithiane
Authors: Kalff H. T. , Romers C. 
Published: September 2010

Abstracttrans‐2,5‐Dibromo‐1,4‐dithiane crystallizes in the monoclinic system; the space group is P21/c with a = 6.42, b = 7.12, c = 9.01 Å, β = 111.6°, and Z = 2. The structure was solved from a three‐dimensional Patterson function and refined by the least‐squares method using room temperature reflexion data. The dithiane ring has the chair conformation with the bromine atoms in axial positions. Large values (115°) are observed for the valency angles CCS, all other bond angles and bond distances being normal.
Mass spectral identification of the methyl esters of 2,4‐dinitrophenylamino‐acids
Authors: Penders Th. J. , Copier H. , Heerma W. , Dijkstra G. , Arens J. F. 
Published: September 2010

AbstractThe methyl esters of 2,4‐dinitrophenylamino‐acids are suitable for mass spectral analysis of amino‐acids in peptide hydrolysates.
Studies in homogeneous catalysis: Di‐tert‐butyl nitroxide as promoter of the copper‐catalysed oxidation of methanol by oxygen
Authors: Brackman W. , Gaasbeek C. J. 
Published: September 2010

AbstractThe oxidation of methanol by oxygen, catalysed by copper‐phenanthroline complexes and promoted by the stable radical di‐tert‐butyl nitroxide, has been studied. The results are discussed in connection with the previously studied oxidation of methanol by copper‐phenanthroline complexes, catalysed by di‐tert‐butyl nitroxide, in the absence of oxygen.Similar systems in which ammonia was used instead of phenanthroline were also investigated, both under aerobic and anaerobic conditions. The results indicate that the promoter, di‐tert‐butyl nitroxide, is not involved in any reactions in which oxygen or radicals derived from oxygen participate, but that its sole function is to catalyse the reduction by methanol of cupric complex to the cuprous state. If oxygen is present, the cuprous ion then reacts with one mole of oxygen, yielding cupric complex and \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm O}_{\rm 2}^{-\bullet}\]\end{document}, whereupon the \documentclass{article}\pagestyle{empty}\begin{document}\[{\rm O}_{\rm 2}^{-\bullet}\]\end{document} reacts with methanol coordinated to cupric ion, as in the aerobic oxidation of methanol catalysed by unpromoted copper‐phenanthroline complexes, described in the previous paper.Chain reactions propagated by hydroxymethyl radicals do not occur in the present reaction.
Purification des substances organiques par fusion de zone: Un appareil permettant de traiter un kilogramme de produit
Authors: Maire Jean Claude , Delmas Marc Arthur 
Published: September 2010

AbstractL'appareil décrit permet l'extension de l'application de la méthode de fusion de zone, au traitement d'une quantité de produit organique voisine du kilogramme. Il appartient à la série des appareils dont le tube est vertical et les zones chauffantes fixes. La vitesse du tube, entraîné par un système hydraulique, est comprise entre 10 et 40 mm par heure. La chauffage est assuré par six résistances et régulé par un pyrectron. Deux essais sur des mélanges synthétiques confirment l'efficacité de la méthode ainsi adaptée à cette échelle, et surtout le grand progrès apporté par l'introduction d'un tuyau flexible de téflon destiné à absorber les variations de volume du produit.
On the oscilloscopic determination of rate constants of electrode reactions by means of square wave and sine wave current: I. The moment of zero diffusion polarization in the square wave case
Authors: Teppema P. , Sluyters‐Rehbach M. , Sluyters J. H. 
Published: September 2010

AbstractA new and simple derivation of the diffusion polarization as a function of time is presented for the case wherein a square wave current passes an electrode‐solution interface. The moment of zero diffusion polarization, which was already known to be 0.09, is calculated more precisely to be 0.094 of the whole period of the square wave signal. The consequences as regards the cyclic current step method for the determination of rate constants of electrode reactions, are discussed.
Polynuclear heterocyclic systems. III: Reaction of 2‐aminocyclanones with dimethyl acetylenedicarboxylate
Authors: Pandit U. K. , Huisman H. O. 
Published: September 2010

AbstractThe condensation of cyclic α‐aminoketones II, III and IV with dimethyl acetylenedicarboxylate has been studied. The reaction of II provides a convenient new route to 4,5‐dihydro‐3H‐benz(e)indolecarboxylic acids and esters. NMR spectra of the latter compounds afford a method for recognizing the position of the ester function in certain isomeric esters.
Syntheses of carotenoidal compounds. I. Preparation of some substituted polyenes with a cross‐conjugation
Authors: Haeck H. H. , Kralt T. , van Leeuwen P. H. 
Published: September 2010

AbstractThe syntheses and absorption spectra in visible light of condensation products of retinal and retinylideneacetone with several cyanoacetic esters and related compounds are reported.
1,1,2‐Triphenylethylenes with trifluoromethyl substituents
Authors: Buu‐Hoï N. P. , Nam N. H. , Xuong N. D. 
Published: September 2010

AbstractA number of 1,1,2‐triphenylethylenes bearing trifluoromethyl substituents in various positions have been synthesized and their oestrogenic activity investigated. It is shown that the introduction of trifluoromethyl groups decreases the oestrogenicity, this effect being more pronounced in the para derivatives than in the ortho and meta isomers. Possible explanations for this effect are discussed.
Chemistry of acetylenic ethers 81: synthesis of β‐alkoxy‐β‐chloroacrylic chlorides by addition of phosgene to 1‐alkynyl ethers
Authors: van den Bosch G. , Bos H. J. T. , Arens J. F. 
Published: September 2010

Abstract1‐Alkynyl ethers of the type R‐C≡C‐OR′ (R = H or alkyl and R′ = alkyl) were converted by addition of phosgene into β‐alkoxy‐β‐chloroethene carbonic chlorides RO‐CCl = CR‐CO‐Cl (II). From the adducts some amides were prepared.Hexachloroacetone and chloral reacted with ethoxyethyne without a catalyst to (CCl3)2CCH‐COOC2H5 (I) and CCl3CHCHCOOC2H5 respectively.Sulfur dichloride already adds on to ethoxyethyne at a low temperature, forming bis(2‐ethoxy‐2‐chlorovinyl) sulfide (VIII), which upon alcoholysis yields bis(ethoxycarbonylmethyl) sulfide (IX).
Chemistry of acetylenic ethers 82: On the different influence of alkylthio and alkoxy groups on the course of 1,4‐Eliminations
Authors: van Boom J. H. , Brandsma L. , Arens J. F. 
Published: September 2010

Abstract1,4‐Elimination of alkanethiols RSH from the bis‐thioethers RSCH2CCC;H2SR with sodium ethoxide in liquid ammonia at −33°, affords two products viz. enynyl thioethers CH2CHC≡CSR and dienyl‐bis‐thioethers CH2CH‐C(SR)CHSR resulting from readdition of thiolate. Experimental evidence for the occurrence of cumulenyl thioethers CH2CCCHSR as intermediates in these elimination reactions is described.Reaction of the “mixed” compounds RSCH2C≡CCH2OR′, RSCH2C≡CCH(CH3)OR′ and RSCH2C≡C‐C(CH3)2OR′ with sodium ethoxide at −33° in liquid ammonia results in an elimination of the OR′ [R′ = alkyl or ‐CH(CH3)OC2H5] group and formation respectively of the enynyl thioethers RSC≡CCHCH2, RSC≡CCHCHCH3 and a mixture of RSC≡CCHC(CH3)2 and the carbinolRSCH≡C(OH)(CH3)] = CCH–CThe carbinol can also be obtained by reaction of RSCHCCHC(CH3) = CH2 with lithium amide and acetaldehyde.
Reserpine analogues V: Optical antipodes of two methoxy‐β‐phenylethylaminoalkyl methoxybenzoates
Authors: Kralt T. , Haeck H. H. , Peperkamp H. A. 
Published: September 2010

AbstractPreparation of the optical antipodes of I and of II is described. The absolute configuration of the antipodes is determined, correlating the structures with that ofD(+)paredrine. The musculotropic as well as the neurotropic activities of the antipodes are given.
Chemistry of 1,2‐di‐tert.Butylbenzene and derivatives i. nitration of 1,2‐di‐tert.butylbenzene
Authors: van de Graaf B. , Wepster B. M. 
Published: September 2010

AbstractNitration of 1,2‐di‐tert.butylbenzene gives, in addition to 4‐nitro‐1,2‐di‐tert.‐butylbenzene, a remarkably high percentage of 3‐nitro‐1,2‐di‐tert.butylbenzene. Upon further nitration of these compounds, 3,5‐dinitro‐1,2‐di‐tert.butylbenzene and 4,5‐dinitro‐1,2‐ditert.butylbenzene are formed from the 4‐nitro derivative, and 3,4‐dinitro‐1,2‐di‐tert.butylbenzene and 3,5‐dinitro‐1,2‐di‐tert.butylbenzene from the 3‐nitro derivative.
Tetracyclic γ‐carboline derivatives: Synthesis of 2,8‐substituted octahydroindolo[3,2‐α]quinolizines
Authors: Corts G. J. B. , Nauta W. Th. 
Published: September 2010

AbstractThe preparation of a number of 2,8‐substituted 1,2,3,4,6,7,8,12c‐octahydroindolo[3,2‐α]quinolizines, using a 2‐(2‐aminoethyl)indole derivative and 3‐substituted glutaric anhydrides, or 3‐substituted 5‐bromovalerates, as starting materials, is described.
Studies on imidazoles, part II: The action of phosphorus pentachloride on some symmetrical N,N′‐dialkyloxamides
Authors: Trout G. E. , Levy P. R. 
Published: September 2010

AbstractA series of 5‐chloro‐1,2‐dialkylimidazoles have been prepared in good yield by the action of phosphorus pentachloride on a series of symmetrical N,N′‐dialkyloxamides and their infra‐red spectra recorded.
Catalyst specificity in the benzoin type condensation of picolinaldehyde. A direct test for cyanide ion
Authors: Poziomek E. J. , Kronenberg M. E. , Havinga E. 
Published: September 2010

AbstractOf thirty‐five reagents tested only cyanide rapidly catalyzes the formation of α‐pyridoin from picolinaldehyde in water. Visual observation of product precipitating offers a rapid and specific method of detecting cyanide at concentrations of 5 μg per ml or higher.
Preparation of dithioesters from alkynethiolates and thiols: Evidence for the intermediate occurrence of thioketenes
Authors: Schuijl P. J. W. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractDithioesters magnified image have been obtained in satisfactory yields by adding ethereal solutions of lithium alkynethiolates, RCCSLi, to an excess of a thiol. Thioketenes RCHCS are supposed to be intermediate species.
The synthesis of 1‐ and 2‐alkyladamantanes
Authors: Hoek W. , Strating J. , Wynberg Hans 
Published: September 2010

AbstractWhen thiophene is alkylated with 1‐bromoadamantane a separable mixture of 2‐(1‐adamantyl)thiophene and 3‐(1‐adamantyl)thiophene is formed. Using 2‐bromoadamantane a similar mixture of 2‐(2‐adamantyl)thiophene and 3‐(2‐adamantyl)thiophene is formed. Desulfurization furnished the corresponding alkyl adamantanes.
Synthesis of β‐diazosulfones
Authors: Strating J. , Heeres J. , van Leusen A. M. 
Published: September 2010

AbstractThree β‐diazosulfones are obtained by alkaline fission of N‐(2‐arylsulfonylethyl)‐N‐nitrosourethanes. Alternative approaches, i.e. oxidation of phenylsulfonylacetone hydrazone and alkaline decomposition of the corresponding tosylhydrazone, did not succeed.
The addition of bromine chloride to some cyclohexene derivatives
Authors: Hageman H. J. , Havinga E. 
Published: September 2010

AbstractThe addition of bromine chloride, prepared in situ from N‐bromosuccinimide and hydrogen chloride, to a number of alkyl cyclohexenes has been studied. The addition leads to mixtures of isomeric trans‐bromochloroalkylcyclohexanes. A two‐stage mechanism, involving the formation of a cyclic bromonium‐ion intermediate, followed by a trans‐diaxial opening of the cyclic intermediate is proposed to account for the experimental results.
Specificity in the enzymic conversion of polyunsaturated fatty acids into prostaglandins
Authors: Struijk C. B. , Beerthuis R. K. , Pabon H. J. J. , van Dorp D. A. 
Published: September 2010

AbstractThe enzyme specificity in the biosynthesis of prostaglandins has been investigated by incubation of a particulate fraction of sheep vesicular glands with ω6 tri‐ and tetraenoic C18 ‐ C22 fatty acids and isomers of ω6 eicosatrienoic acid (20: 3 ω6). The chemical synthesis of the various substrate fatty acids is described. The tetraenoic fatty acids were converted into a series of prostaglandin E2 homologues and the trienoic fatty acids into a series of prostaglandin E1 homologues. The only isomer of 20: 3 ω6 which showed a fairly high conversion into an isoprostaglandin E1 was the ω7 compound. Maximum conversions were obtained from ω6 C20 acids.The smooth muscle stimulating activity of prostaglandin E1 and E2 appears to be very specific. All other prostaglandins had much lower activities.
Ketene thioacetals from dithioesters
Authors: Schuijl P. J. W. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractKetene thioacetals R′CH=C(SR″) (SR′″) (with R′=H or alkyl and R″, R′″=alkyl) have been obtained in very good yields by treatment of dithioesters R′CH2C=S(SR″) with one equivalent of potassium amide in liquid ammonia and subsequent alkylation with alkyl halide R′″Br or R′″I.
Reinvestigation of authentic samples of auxins a and b, and related products by mass spectrometry
Authors: Vliegenthart J. A. , Vliegenthart J. F. G. 
Published: September 2010

AbstractAuthentic samples of auxin‐a, auxin‐b and auxin‐a lactone ‐ discussed in papers from this laboratory in the period 1931‐1944 ‐ are found to be identical with cholic acid, thiosemicarbazide and hydroquinone, respectively. Auxin glutaric acid turns out to be phthalic acid, and the 3,5‐dinitrobenzoyl ester of auxin‐b is ethyl α‐cyanophenylpyruvate.Auxins a and b, as unique individuals, are therefore to be considered as non‐existent.
Proton magnetic resonance spectra of some acetylenic phosphorus compounds
Authors: Drenth W. , Rosenberg D. 
Published: September 2010

AbstractProton magnetic resonance spectra of ethynylphosphines, ethynylphosphine oxides and their saturated analogues have been measured. An analysis of the data indicates the presence of 3d‐orbital participation in the PC bond. This participation seems to be equal in the phosphines and the phosphine oxides.
Evidence for “through‐space” long‐range proton‐proton coupling in acetone
Authors: de Jeu W. H. , Deen R. , Smidt J. 
Published: September 2010

AbstractAccording to the theory of long‐range proton spin coupling by pi electrons, |JHH| in acetone should decrease with increasing polarity of the carbonyl group. Experimentally the opposite has been found. To explain the observed trend a “through‐space” mechanism is proposed. JHH is now interpreted as the result of a negative coupling by the pi electrons and a positive “through‐space” contribution. On this hypothesis a better fit numerically can also be obtained.
The chemistry of polythienyls. Part III: The synthesis of terthienyls
Authors: Kooreman H. J. , Wynberg Hans 
Published: September 2010

AbstractThe synthesis of some terthienyls using 1,2‐ and 1,4‐ diketones as precursors, is described. Most of the 1,4‐diketones are prepared by the Stevens rearrangement of N,N‐di(2‐thenoylmethyl)‐N,N‐dimethylammonium salts followed by elimination of dimethylamine and reduction of the resulting 2‐butene‐1,4‐diones.Of the fourteen possible isomeric terthienyls only four were known prior to this work. Using the methods described two new isomeric systems have been prepared.
Pyrazoles. III. PMR studies of pyrazoles
Authors: Habraken Clarisse L. , Munter H. J. , Westgeest J. C. P. 
Published: September 2010

AbstractSubstituents with electron withdrawing capacities are found to induce a paramagnetic displacement of the chemical shifts of protons and methyl groups in the remaining positions of the pyrazole ring. For the 4‐position this effect is considered to be due primarily to resonance interaction of substituent and pyrazole ring.
A solid‐phase Edman sequence determination
Authors: Dijkstra A. , Billiet H. A. , van Doninck A. H. , van Velthuyzen H. , Maat L. , Beyerman H. C. 
Published: September 2010

AbstractThe sequence of the amino acids in a peptide covalently bound to a polymer could be determined by reaction with methyl isothiocyanate. This extension of the Edman degradation is likely to facilitate the automation of the sequence determination of peptides and proteins.
Optical rotatory dispersion of pelletierine, confirmation of the absolute configuration
Authors: Beyerman H. C. , Maat L. , Visser J. P. 
Published: September 2010

AbstractFrom the difference between the optical rotatory dispersion of pelletierine in acid and in alkaline aqueous solution the absolute configuration was deduced by comparison with 2‐methylpiperidine. It confirms our absolute‐configuration determination by another method. The conclusion contradicts that of a recent publication.
Chemistry of acetylenic ethers 87: Preparation of cumulenyl ethers by 1,4‐elimination
Authors: Montijn P. P. , van Boom J. H. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractCumulenyl ethers of the type R′R″C  C  C  CHOCH3 (with R′ and R″ alkyl) have been prepared in good yields by treatment of bis‐ethers of the type (C2H5O)CH(CH3)OC(R′)(R″)CCCH2OCH3 with two equivalents of sodamide in liquid ammonia.From the bis‐ether (C2H5O)CH(CH3)OCH(CH3)CCCH2OCH3 a mixture of cis and trans CH3CCCH  CHOCH3 was obtained in good yield by the same procedure.
Thermolytic reactions of esters. Part II. Structural effects in the radical decomposition of simple allyl esters
Authors: Louw R. , Kooyman E. C. 
Published: September 2010

AbstractVapour phase thermolysis at 485°C of methallyl acetate and the allyl esters of benzoic, phenylacetic and trifluoroacetic acid proceeds by radical mechanisms analogous to that proposed for allyl acetate1. Rates of primary allyl‐oxygen homolysis appear to depend only slightly on the nature of the acyl moiety.The induced radical decomposition proceeds mainly by addition to ester, followed by β‐elimination, polymerization being unimportant under the present experimental conditions.An explanation is offered for the fact that allyl(ic) esters of aromatic acids ‐ in contrast to those of aliphatic acids ‐ produce a substantial amount of carboxylic acid in addition to the main oxygen‐containing product, carbon dioxide.
Complexes of ligands containing SO: II. Infrared spectra of diphenylsulfoxide compounds
Authors: van Leeuwen P. W. N. M. 
Published: September 2010

AbstractThe infrared spectra of several complexes of diphenylsulfoxide (DPSO) are reported. Only one SO stretching frequency has been found, at lower wavenumbers than in DPSO itself, indicating that all DPSO's are coordinated to the metal ion. The asymmetric stretching frequencies of CIO⊖ and BF4⊖ have been observed as unusually sharp absorptions.
An attempt at the interpretation of the ligand hyperfine structure in the epr‐spectra of mox ‐ions
Authors: Verbeek J. L. , Cornaz P. F. 
Published: September 2010

AbstractIn this contribution we propose a simple model for the observed ligand hyperfine structure in complexes of the type MOX (where M = Cr, Mo, W and X = F, Br), in the limits of the less complicated case I = ½ as is realised with F as the ligand.It is assumed that contact interaction and dipole‐dipole interaction between the unpaired electron and the ligands are the origin of this ligand hyperfine structure.An estimate is made for the energies associated with certain orientations of an external magnetic field with respect to the axes of symmetry of the complex molecule.It is shown that a remarkable resemblance exists between a spectrum based on these assumptions and the spectrum measured at X‐band of a frozen solution of CrOF in 38% hydrofluoric acid.
Photoreactions of aromatic compounds XIII: Photosubstitution of 4‐nitroveratrole with methylamine; a convenient synthesis of N‐methyl‐4‐nitro‐o‐anisidine
Authors: Kronenberg M. E. , van der Heyden A. , Havinga E. 
Published: September 2010

Abstract4‐Nitroveratrole reacts with methylamine in water on illumination with ultraviolet light (mainly 313 mμ) to yield N‐methyl‐4‐nitro‐o‐anisidine as the major product. The reaction is zero order; the quantum yield is 0.19. With dimethyl‐amine as a partner analogous photosubstitution occurs but the reaction is complicated inter alia by the photosensitivity of the products. A short discussion of some practical and theoretical aspects is given.