bluuebunny/crossref_metadata_2025_split huggingface dataset:
The preparation of a new inorganic ring system containing one sulfur, two phosphorus and three nitrogen atoms in the ring
Authors: Baalmann H. H. , Velvis H. P. , van de Grampel J. C. 
Published: September 2010

AbstractThe results of the thermal decomposition at low pressure of Cl3P  NPCl2 ; NSO2Cl, Cl3P  NPCl2  NPCl2  NSO2Cl and mixtures of these compounds with Cl3P  NSO2Cl, are reported. In all cases inorganic heterocycli, containing nitrogen phosphorus and/or sulfur atoms, were obtained. The isolation of the hitherto unknown compound (NPCl2)2 NSOCl is described.A short discussion of the I.R. spectra of α‐(NSOCl)3, NPCl2(NSOCl)2, (NPCl2)2 NSOCl and (NPCl2)3 is given.
Kinetics of the cis‐trans isomerization of the diaquotetra‐amminecobalt(III) cation and conjugate bases
Authors: Balt S. 
Published: September 2010

AbstractA study is reported on the cis‐trans isomerization rates and equilibria of the ions Co(NH3)4(H2O)23+, Co(NH3)4(OH)(H2O)2+ and Co(NH3)4(OH)2+ in acidic and ammoniacal solutions. The relative reaction rates follow the pattern shown by the analogous ethylenediamine complexes, whereas the absolute rates for the ammine complexes studied are a 100 times larger.
A method for determination of tulipalin A and B concentrations in crude extracts of tulip tissues
Authors: Beijersbergen J. C. M. 
Published: September 2010

AbstractA method for determining the concentration of the fungitoxic lactones tulipalin A and B in crude extracts of various parts of the tulip is described. After a simple fractionation of the extracts on Dowex 50 W, the amounts of these compounds can be measured by UV spectrophotometry.
Photochemical cycloaddition of 9,10‐phenanthroquinone to allenes III: A kinetic study
Authors: Boleij J. S. M. , Bos H. J. T. 
Published: September 2010

AbstractPhenanthroquinone was added photochemically to phenyl‐, phenoxy‐, t‐butyl‐, t‐butoxy‐, cyano‐ and bromo‐allene yielding dihydrodioxin derivatives.Quantum yields and rate constants of the reaction of phenanthroquinone with several substituted allenes were determined. For comparison also quantum yields were measured of the reaction of phenanthroquinone with some corresponding alkenes. The influence of substituents on the reaction rates could satisfactorily be correlated with a ρσ‐γER relationship of Yamamotu and Otsu.
Mechanism of the antioxidant action of dialkyl sulfoxides
Authors: Koelewijn P. , Berger H. 
Published: September 2010

AbstractThe main inhibiting action of dialkyl sulfoxides in the autoxidation of hydrocarbons derives from their ability to form sulfenic acids on thermal decomposition. The sulfenic acids are extremely active radical scavengers, the rate constant of the reaction of sulfenic acid and peroxy radicals being at least 107 l.mole−1 · S−1 at 60°C. In the AIBN‐initiated oxidation of tetralin in the presence of sulfoxides one peroxy radical is scavenged per molecule of sulfenic acid. This inhibition can be described kinetically as a reduction of the rate of initiation by an amount equal to the rate of decomposition of the sulfoxide.
The structure of the compound PBr4Cl
Authors: Gabes W. , Olie K. , Gerding H. 
Published: September 2010

AbstractTetrabromophosphonium chloride, PBr4Cl, has been prepared and analysed. The Raman spectrum indicates that the solid consists of PBr+4 and Cl− ions, and is isomorphous with PBr5. From X‐ray powder data the cell constants of the orthorhombic unit cell are calculated from 33 reflexions: a = 5.649 ± 0.014, b = 16.781 ± 0.026 and c = 8.105 ± 0.015 Å.
Amination of alkyl substituted halogenopyridines with potassium amide in liquid ammonia
Authors: van Der Does L. , den Hertog H. J. 
Published: September 2010

AbstractThe action of potassium amide in liquid ammonia on several methyl substituted 3‐ and 4‐bromo(chloro)pyridines, of 5‐bromo‐2‐t‐butylpyridine and of 3‐bromo (chloro) and 4‐bromo(chloro)‐2,6‐dimethylpyridine has been studied.The results of the reactions indicate the occurrence of derivatives of 3,4‐didehydropyridine as intermediates. An interpretation is given of the influence of the substituent and the hetero atom on the course of the aminations.
Synthesis of 1,3‐thiazepines and 1,3‐benzo[e]thiazepines
Authors: Reinhoudt D. N. 
Published: September 2010

AbstractTwo routes are described for the synthesis of 1,3‐benzo[e]thiazepines, a novel class of heterocyclic compounds. The first route is a reaction between 2‐bromo‐methylbenzyl or 2‐bromomethylbenzoyl bromide and a thioamide or a thiourea. In an analogous reaction a 1,3‐thiazepine can be synthesized from 4‐bromobutyryl chloride and N,N′‐diphenylthiourea. The second route comprises cyclization of N′‐(2‐bromomethylbenzoyl)‐N′‐disubstituted thioureas. Rather unexpectedly, the corresponding N′‐monosubstituted compounds yielded benzo[c]pyrrolidine derivatives. Pyrrolidines were observed from the cyclization of N′‐(4‐bromobutyryl)‐N′‐mono/disubstituted thioureas.The reaction mechanisms and the spectroscopic data of the reaction products are discussed.The 1,3‐benzo[e]thiazepines were converted into the corresponding β‐lactams by reaction with diphenylketene.
Synthesis of (E)‐(2S)‐2‐amino‐4‐methylthio‐3‐butenoic acid („dehydro‐L‐methionine”︁)
Authors: Balenović K. , Deljac A. 
Published: September 2010

Abstract(E)‐(2S)‐2‐Amino‐4‐methylthio‐3‐butenoic acid (1; “dehydro‐L‐methionine”) was prepared through reaction stages 2‐7 using β‐acetamido‐β, β‐di(ethoxycarbonyl)propionaldehyde as starting material.
Ethylzinc 1,3‐bis(diphenylphosphino)‐1‐propenyl oxide, an unexpected product of the reaction between ethylzinc diphenylphosphide and β‐propiolactone
Authors: Boersma J. , Noltes J. G. 
Published: September 2010

AbstractEthylzinc diphenylphosphide effects the acyl‐oxygen ring‐opening of β‐propiolactone. However, the product of insertion into the ZnP bond spontaneously eliminates ethylzinc hydroxide with formation of acryloyldiphenylphosphine which undergoes a 1,4‐addition, not previously observed, with a second molecule of ethylzinc diphenylphosphide. The course of this unexpected reaction sequence and the structure of the final product have been elucidated by IR and NMR (1H, 31P and 13C) spectroscopy.
Halogen migration in reactions of halogeno derivatives of some five‐membered hetarenes with potassium amide in liquid ammonia (IV)
Authors: de Bie D. A. , van der Plas H. C. , Geurtsen G. , Nijdam K. 
Published: September 2010

AbstractOn treatment of 5‐bromo‐3‐methyl‐1‐phenylpyrazole, 2‐bromobenzo[b]thiophene and 2‐bromobenzo[b]thiophene‐1,1‐dioxide with potassium amide in liquid ammonia bromine migration to the adjacent carbon atom was observed. Considerable evidence for the occurrence of an intermolecular transbromination was obtained.
(tert‐Butyl isocyanide) (ethanol)nickel(II) chloride
Authors: Stephany R. W. , Nolte R. J. M. , Drenth W. 
Published: September 2010

AbstractThe synthesis, isolation and characterization of the stable complex [NiCl2 (t‐C4H9NC)(C2H5OH)] is described. Spectral and magnetic data are provided.
Complex formation between derivatives of 1‐nitroazulene and methoxide ion in methanol
Authors: Lok C. M. , den Boer Maria E. , Cornelisse J. 
Published: September 2010

AbstractCertain 3‐substituted 1‐nitroazulenes in methanol with sodium methoxide form complexes with methoxide ion. Complex formation occurs mainly when the substituent at position 3 is meta‐directing with respect to electrophilic aromatic substitution; the electron withdrawing capacity of the substituent appears to be the main factor determining the extent of complex formationAccording to the electronic absorption spectra and the nuclear magnetic resonance spectra 1,3‐dinitroazulene gives a complex in which the methoxide ion is attached to carbon atom 6. The complex formed from 1‐nitro‐3‐trifluoroacetylazulene has the methoxy group at the carbon atom of the carbonyl group.The complexes are in equilibrium with the uncomplexed nitroazulenes and do not give rise to substitution products.
Koch‐Haaf carboxylations. part II Carboxylation of 1‐alkylcyclohexanemethanols, 1‐(1‐alkylcyclohexane)ethanols, and 1‐methyl substituted spiro [2.5]octanes
Authors: Peters J. A. , van Bekkum H. 
Published: September 2010

AbstractThe Koch‐Haaf carboxylation of a series of 1‐alkylcyclohexanemethanols and 1‐(1‐alkylcyclohexane)ethanols has been studied. In the initial cation the 1‐alkyl group always migrates into the side chain, yielding tertiary carboxylic acids. An exception is the carboxylation of 1‐(1‐adamantane)ethanol, which gives the corresponding secondary acid besides 3‐ethyladamantanecarboxylic acid. The latter compound is formed probably from the initial carbonium ion after a bimolecular hydride shift.The carboxylation of 1‐methyl substituted spiro[2.5]octanes has been investigated. Steric factors appear to determine the edge of the cyclopropane ring which is opened preferentially.
Interaction between t‐butyl hydroperoxide (I) and “positive halogen” compounds. part I. Intermediates in the reaction between I and CI2O
Authors: van Ham J. , Schors A. , Kooyman E. C. 
Published: September 2010

Abstract“positive halogen” compounds were found to induce the decomposition of t‐butyl hydroperoxide (I) in the dark. In this Cl2O proved to be particularly effective, liberating oxygen from I instantaneously at 0°. At temperature between −80° and −30°, two oxygen‐rich intermediates could be observed with the aid of NMR‐spectroscopy. t‐Butyl peroxyhypochlorite (But‐O‐O‐Cl) was formed immediately; di‐t‐butyl trioxide (ButOOOBut) apparently resulted from a slower reaction, found to be promoted by alkali. By using a solution of di‐t‐butyl trioxide thus obtained, the polymerization of methyl acrylate could be initiated at a temperature as low as −20°.
Electrochemical reduction of aza aromatics. Part IV Electrochemical dimerization of pyrimidine to 4,4′‐bipyrimidine
Authors: van 'T Land E. , van der Meer D. 
Published: September 2010

AbstractESR spectra show that pyrimidine dimerizes to 4,4′‐bipyrimidine in dimethyl‐formamide (DMF). The coupling constants in 4,4′‐bipyrimidine have been determined. Cyclovoltammetric experiments indicate that the disappearance of the mononegative ion of pyrimidine cannot be described by a simple mono‐ or bimolecular deactivation. The heterogeneous reaction rate constants (ks.h) have been determined by a.c. polarography. It can be deduced from the reduction potentials that dimerization of pyrimidine cannot be used for the synthesis of 4,4′‐bipyrimidine.
On the mechanism of the reaction of 4‐chloro‐5‐cyano‐6‐phenylpyrimidine with potassium amide in liquid ammonia at −75°: A 15N‐ and 14C‐study of the conversion of 4‐chloro‐5‐cyano‐6‐phenylpyrimidine into 4‐amino‐5‐cyano‐6‐phenylpyrimidine
Authors: de Valk J. , van der Plas H.C. 
Published: September 2010

AbstractBy treatment with potassium amide in liquid ammonia at −75°, 4‐chloro‐5‐cyano‐6‐phenylpyrimidine is converted into 4‐amino‐5‐cyano‐6‐phenylpyrimidine; 1‐amino‐2,2‐dicyano‐1‐phenylethene is formed as a minor reaction product. Evidence is presented, using the labelled compounds 4‐chloro‐5‐cyano‐6‐phenyl‐[1(3)‐15N]‐ and 4‐chloro‐5‐[14C]cyano‐6‐phenylpyrimidine that i the conversion into the corresponding 4‐amino compound proceeds completely according to the ANRORC mechanism, ii the 14C‐cyano function remains nearly completely extranuclear. The synthesis of the 15N‐ and 14C‐labelled 4‐chloro‐5‐cyano‐6‐phenylpyrimidines is described.
NMR Experiments on acetals 34: The conformational equilibrium in trans‐6‐alkyl‐4‐methyl‐ and trans‐6‐alkyl‐4‐phenyl‐1,3‐dioxanes. The conformational free energy of the 4‐methyl and 4‐phenyl groups in 1,3‐dioxanes
Authors: Anteunis M. , Tavernier D. , Swaelens G. 
Published: September 2010

AbstractThe conformational chair‐chair equilibrium in trans‐6‐alkyl‐4‐methyl‐, and trans‐6‐alkyl‐4‐phenyl‐1,3‐dioxanes has been determined by NMR spectroscopy. The equilibrium constant was calculated with the aid of coupling constants, and involved the use of model compounds. The experimental order of conformational preferences of the alkyl groups is i‐Pr > Et > Pr ≈︁ i‐Bu ≈︁ neoPe ≈︁ Me, in agreement with theory. Base catalyzed epimerization of cis‐, and trans‐6‐methyl‐4‐phenyl‐1,3‐dioxane, together with the conformational equilibrium in the trans isomer, investigated here allows the evaluation of ΔG°303 values of 4‐Me and 4‐Ph: 2950 and 2850 cal./mole, respectively.
Homogeneous hydrogenation and isomerisation of alkenes by means of μ‐dichloro(π‐benzene)ruthenium(II)
Authors: Hinze A.G. 
Published: September 2010

AbstractProlonged treatment of μ‐dichloro(π‐benzene)ruthenium(II) with hydrogen in dimethylformamide solution results in the formation of a catalyst allowing of a rapid and homogeneous hydrogenation of compounds containing alkenic bonds. The hydrogenation rates of 1‐alkenes, cycloalkenes, and alkenes containing functional groups have been studied quantitatively.The kinetics of the hydrogenation of cyclooctene can be described by the rate expression:R=A[Ru] [H2][S]/(B + C[S])where A, B and C are constants and [Ru], [H2] and [S] the catalyst, hydrogen and alkene concentration, respectively. From the hydrogenation data obtained for cyclooctene, the activation energy was calculated to be ca 6 kcal. mole−1.The results of experiments involving isotopic exchange with molecular hydrogen‐deuterium gas mixtures and the incorporation of deuterium during the deuterogenation of cyclooctene suggest that the actual active catalytic species is (π‐benzene)Ru‐H.
The metabolism of hydroxyanthranilic acids. Part IV: The isolation and some of the properties of 3‐hydroxyanthranilate oxygenase from monkey liver
Authors: Savage Nerina , Soldin S. J. , Levy P. R. 
Published: September 2010

Abstract3‐Hydroxyanthranilate oxygenase was purified 250‐930 fold from a hitherto unexamined source, the cytoplasmic fraction of the liver of the African Vervet monkey. The purification steps included extraction, heating, ammonium sulphate fractionation, acetone precipitation, chromatography on Sephadex G‐100 and or G‐200 and calcium phosphategel treatment. Final preparations of the enzyme ranged in specific activity from 5.5‐24.4. Starch‐gel electrophoresis at pH 8.6 indicated protein heterogeneity but more than one of the protein bands was active. Attempts to separate these active forms on DEAE‐ or CM‐cellulose were not successful due to marked instability of the preparations. The enzyme from monkey liver also requires Fe+ + for activity and is protected from inactivation by the presence of dithiothreitol.The Km for 3‐hydroxyanthranilate is 40μM.
Isomerization, disproportionation, methylation and sulfonylation in the reaction of polyalkylbenzenes with methanesulfonic acid
Authors: Willard E. G. , Cerfontain H. 
Published: September 2010

AbstractThe reaction of the three tri‐, the three tetra‐methylbenzenes, 1,3,5‐triethylbenzene, 1,3,5‐tri‐ and 1,2,4,5‐tetra‐isopropylbenzene with methanesulfonic acid, was studied at 180°. The tri‐ and tetra‐methylbenzenes react with formation of a mixture of hydrocarbons which, for long reaction times, contains all the polymethylbenzenes except toluene. Equilibrium isomer ratios for the di‐ and tri‐alkylbenzenes and the tetra‐methylbenzenes are reported. The hydrocarbon products are formed by intramolecular alkyl migration, transalkylation and dealkylation. The xylene equilibration takes place only by transmethylation.The hydrocarbons are sulfonylated further and methylated by the methanesulfonic acid reagent. The sulfonylation is far less important with durene than with hemimellitene and m‐xylene.The reactions are accompanied by tar formation.
Proton magnetic resonance studies of specifically deuterated cyclohexane compounds: Part III. Long‐range couplings (4JHH) in cyclohexane
Authors: Remijnse J. D. , Vandeginste B. G. M. , Wepster B. M. 
Published: September 2010

AbstractThe preparation of 1,1,3‐triprotoperdeuterocyclohexane is reported. The low‐temperature PMR spectrum of this compound shows a superposition of two 3‐spin systems, originating from the two chair conformations. A long‐range coupling constant between the equatorial protons at positions 1 and 3 of 1.7 Hz is derived. The coupling between the 3‐axial proton and the 1‐protons is smaller than 0.4 Hz.
New reactive intermediates from carbon‐sulfur bond cleavage in heterocyclic compounds
Authors: Hoff S. , Blok A.P. , Zwanenburg E. 
Published: September 2010

AbstractThe sulfur‐carbon bond cleavage with alkali metals in liquid ammonia has been investigated in several heterocycles. Special attention has been paid to substituted 1,4‐thiazin‐3‐ones VIII in which the carbon‐sulfur bond is cleft selectively with formation of the dianion X. The protonation, alkylation and acylation of the alkenethiolates X and XI have been studied. Routes to the synthesis of 2,3‐dihydro‐4H‐1,4‐thiazine XIX and tetrahydro‐1,4‐thiazepine XX have been developed.
Chemistry of acetamidoalkenethiolates III. Synthesis of substituted 1,4,2‐oxathiazines and 1,3,4‐thiadiazines
Authors: Hoff S. , Zwanenburg E. 
Published: September 2010

AbstractSubstituted 6‐acetamido‐5,6‐dihydro‐1,4,2‐oxathiazines and 5‐acetamido‐5,6‐dihydro‐1,3,4‐thiadiazines have been prepared in high yields from sodium 2‐acetamidoalkenethiolates by reaction with hydroximic acid chlorides and hydrazonic acid chlorides, respectively. The scope of the reaction has been explored. The conformation of the 1,4,2‐oxathiazines has been proposed on the basis of PMR‐spectroscopic data.
13C N.M.R. and charge distribution in arylcyclobutenyl cations. Part II
Authors: van der Hout‐Lodder S. A. E. , de Haan J. W. , van de Ven L. J. M. , Buck H. M. 
Published: September 2010

Abstract13C N.M.R. spectra of I, II, III, IV and V have been measured and a number of important assignments made. The resulting chemical shifts are correlated with calculated charge densities. Compound IV has been compared with the tetraphenylcyclobutadiene dication in the literature.
α,β‐Unsaturated acetals: Synthesis and mechanism of formation
Authors: de Leeuw J. W. , de Waard E. R. , Beetz T. , Huisman H. O. 
Published: September 2010

AbstractThe conversion of α,β‐unsaturated enones (6) to α,β‐unsaturated acetals (7) is described. The formation is shown to proceed via displacement of H2O in the intermediate hemiacetal. Fumaric acid is shown to be the catalyst of choice for the reaction from 6 to 7.
Structure and conformational equilibration of protonated tertiary alkanoic acids in HF solution
Authors: Brouwer D. M. , Kiffen A. A. 
Published: September 2010

AbstractThe most stable conformations of some protonated tertiary carboxylic acids in HF‐BF3 and HF‐SbF5 have been shown to be those which have one OH proton syn and the other anti to the alkyl groups. In HF solutions, the intramolecular interconversions between the two degenerate conformations is much faster with tertiary than with secondary or primary carboxylic acids; with the tertiary acids it is likely to proceed via the trans‐trans rather than the cis‐cis con‐former as an intermediate. The conformational equilibration of protonated pivalic acid is much faster in HF solution than in FSO3H‐SbF5‐SO2ClF solution.
Proton catalysed hydride transfer from alkanes to methylated benzyl cations: Part I: Kinetics
Authors: van Pelt P. , Buck H. M. 
Published: September 2010

AbstractHydride transfer from isoalkanes to methylated benzyl cations in strong proton acids and proton exchange between isoalkanes and strong proton acids have comparable velocities. The rate of proton exchange between isobutane and several strong proton acids has been studied by PMR line broadening and the following parameters were obtained: (with HSO3F) ΔH≠ = 5.5 kcal/mole., ΔS≠ = ‐35 cal/mole.°K; (with CF3SO3H) ΔH≠ = 4.3 kcal/mole., ΔS≠ = ‐43 cal/mole.°K.Using 2‐2H‐isobutane and tritiated HSO3F, labelled hexamethylbenzene was prepared via hydride transfer to pentamethylbenzyl cations at various temperatures. The analyses for deuterium and tritium were combined with the known rates of proton exchange to get an estimate for the rate of hydride transfer and the corresponding activation parameters: ΔH≠ = 1 kcal/mole., ΔS≠ = ‐46 cal/mole.°K.
Conjugation in thiophene dioxides: Vibrational frequencies and hydrogen bonding ability
Authors: de Jong F. , Janssen M. J. 
Published: September 2010

AbstractThe interaction of the sulfonyl group with an adjacent unsaturated centre has been studied by IR spectroscopy. The sulfur‐oxygen stretching frequencies of thiophene dioxides are compared with those of the open‐chain counterparts. The observed differences indicate a small contribution of “ketonic” type of resonance to the ground state of thiophene dioxides. The same result is obtained using the internal relationship between SO stretching frequencies and hydrogen bonding abilities.Qualitatively, these experimental results are in good agreement with the characteristics of the SO2 moiety, as obtained from HMO calculations.
Nucleophilic substitution of aromatic bromine in 2‐bromobenzophenone by Grignard reagents
Authors: Jongsma C. , Bickelhaupt F. 
Published: September 2010

AbstractThe reaction of 2‐bromobenzophenone (1) with methyl, ethyl, and phenyl Grignard reagents was found to involve substantial substitution of bromine by the organic group of the Grignard reagent It is shown that substitution occurs by intramolecular nucleophilic substitution of a ketone‐Grignard complex (9). The mechanistic implications of this reaction are discussed.
Chemistry of cyclopropene III: Synthesis of mono‐ and dialkylated cyclopropenes
Authors: Schipperijn A. J. , Smael P. 
Published: September 2010

AbstractA simple method has been developed for the preparation of 1‐monoalkyl‐ and 1,2‐dialkyl‐cyclopropenes from cyclopropene and alkyl halides which is in many instances superior to those reported in the literature. High product yields are obtained with primary β‐unsubstituted halides and moderate yields when primary β‐monosubstituted halides are employed. The method is not applicable to primary β‐disubstituted, secondary and tertiary halides. In principle it can also be used for the synthesis of alkylcyclopropenes that bear functional groups in the carbon chain.The strain‐releasing migration of the double bond in the cyclopropene product from the endocyclic to the exocyclic position can, in most cases, be successfully prevented by choosing proper reaction conditions.
Transition‐metal‐catalysed cheletropic elimination of carbene and oxygen from seven‐membered ring systems
Authors: Volger H. C. , Hogeveen H. , Roobeek C. F. 
Published: September 2010

AbstractIn the presence of catalytic amounts of [Rh(CO)2Cl]2 the monomethylene adduct of hexamethylbicyclo[2.2.0]hexa‐2,5‐diene (1) can be quantitatively converted into hexamethylbenzene and a monomethylene carbenoid species; the latter can be trapped by cyclohexene. The hexamethylbenzene is presumably formed via (a) catalysed electrocyclic opening of the cyclobutene ring in coordinated 1 to give coordinated hexamethylnorcaradiene, and (b) extrusion of the carbenoid species. The proposed reaction pathway is supported by the fact that penta‐ and hexamethylcycloheptatriene are also subject to the extrusion reaction in the presence of the catalyst. Under the same catalytic conditions 1,6‐dimethyl‐oxepine is quantitively converted into o‐xylene.Apart from the aromatization the catalyst effects double‐bond isomerization of the methyl‐substituted cycloheptatrienes.
Synthesis of β‐phenylethylamine derivatives XN‐(hydroxy‐ and methoxy‐aralkyl) derivatives
Authors: van Dijk J. , Moed H. D. 
Published: September 2010

AbstractThe synthesis and some pharmacological properties are described of compounds of the general structure:magnified imageThe series contains strong and/or selective utero‐relaxing agents. Stereoisomers of two interesting compounds were separated and characterized, and their configurations were established.