bluuebunny/crossref_metadata_2025_split huggingface dataset:
Absolute configuration and optical rotatory dispersion of 2‐ethylpiperidine and some of its derivatives in connection with a sector rule
Authors: Beyerman H. C. , van den Bosch S. , Breuker J. H. , Maat L. 
Published: September 2010

AbstractThe absolute configuration of optically active 2‐ethylpiperidine has been established both by chemical correlations and by optical rotatory dispersion measurements. The (+)‐compound has the S‐configuration.The ORD of 2‐ethyl‐1‐nitrosopiperidine is discussed in connection with a sector rule for N‐nitrosoamines.
Nitroso compounds. Part XXI: Photolysis of gem‐chloronitrosoadamantane in benzene and in alcohols
Authors: Kayen A.H.M. , Subramanian L.R. , de Boer Th. J. 
Published: September 2010

AbstractPhotolysis in benzene of gemchloronitrosoadamantane‐a model compound with no “active” α‐hydrogen ‐ yields adamantanone (51%) and gem‐dichloro‐adamantane (44%).In hydrogen‐donating solvents like methanol or isopropanol the dichloro derivative is not formed, and the main products are the ketone (38%) and its oxime (55%).In inert solvents the excited nitroso group releases nitric oxide, which interacts with ground‐state starting material to give presumably an unstable diazonium nitrate, a logical precursor of all the stable end‐products observed.On the other hand, in hydrogen‐donating solvents the excited nitroso group first reacts with the alcohol, followed by loss of chlorine and formation of the oxime. This mechanism explains the oxime formation better than do existing theories, in which reaction with the solvent is proposed to occur after initial release of chlorine from the excited chloronitroso compound.
The photolysis of some gem‐chloronitroso compounds
Authors: Duynstee E. F. J. , Mevis M. E. A. H. 
Published: September 2010

AbstractThe red‐light photolysis of 3‐chloro‐3‐nitrosopentane was studied in various solvents. Photolysis in isopropanol gave 95% of HCl, ∼ 60% of 3‐pentanone oxime and ∼ 20% of 2‐oximino‐3‐pentanone (not 3‐oximino‐2‐pentanone). Photolysis in benzene gave none of these products but yielded five other products instead (together 95%) and nitrogen. The red‐light photolysis of 1‐chloro‐1‐nitrosocyclododecane was also briefly studied in two different solvents but here solvent effects seem to be less pronounced. Mechanisms are proposed to explain the solvent effects. With both gem‐chloronitroso compounds only very weak ESR signals were observed during the photolysis.
Synthesis of a series of polyunsaturated fatty acids, their potencies as essential fatty acids and as precursors of prostaglandins
Authors: Beerthuis R. K. , Nugteren D. H. , Pabon H. J. J. , Steenhoek A. , van Dorp D. A. 
Published: September 2010

AbstractA series of polyunsaturated fatty acids has been tested on essential fatty acid activity and as precursors of prostaglandins. It was confirmed that biological activity ofall‐cis8,11,14‐trienoates and 5,8,11,14‐tetraenoates is restricted to acids with 19, 20 or 21 carbon atoms.All‐cis8,11,14‐eicosapolyenoates with extra double bonds at positions 2, 3 or 4 are also biologically active, On the other hand, an additional double bond in the ω‐chain of the molecule, e.g. at the 18th position, leads to nearly complete loss of activity.
Solubilities of some tetra‐alkyl‐carbon, ‐silicon,‐germanium and ‐tin compounds in mixtures of water with methanol, ethanol, dioxane, acetone and acetic acid and differences between the standard chemical potentials of these solutes in their solutions in water and in the mixed or nonaqueous solvents, at 25°C
Authors: de Ligny C. L. , van Der Veen N. G. 
Published: September 2010

AbstractThe solubilities at 25° of 2.2‐dimethylpropane, 3,3‐diethylpentane and tetraethylsilicane have been determined in mixtures of water with methanol, ethanol, dioxane, acetone and acetic acid. The solubilities of tetramethylsilicane, tetramethylgermanium, tetramethyltin, tetraethyltin and tetrapropylgermanium have been determined in mixtures of water with methanol only.All determinations have been performed using gas chromatography.The differences between the standard chemical potentials of these solutes in their solutions in water and in the mixed or nonaqueous solvents have been calculated.The applicability of Pierotti's theory to the solutions in water, methanol, ethanol and acetone, and also in N‐methylformamide, has been investigated.
Chemistry of cyclopropene preparation and reactivity of the cycloprop‐1‐enyl anion in liquid ammonia: (Preliminary communication)
Authors: Schipperijn A.J. 
Published: September 2010

AbstractIt has long been recognized that the vinylic hydrogens of cyclopropene have an acidity comparable to that of the hydrogens of acetylene1, but it is only in isolated cases that this property has been turned to advantage in the synthesis of substituted cyclopropene derivatives2‐7. In this communication we report the preparation of the cycloprop‐1‐enyl anion and its reaction with cyclopropene and alkyl halide.
On the mechanism of the reaction of 4‐bromo‐6‐phenylpyrimidine with potassium amide in liquid ammonia at ‐75°1,2
Authors: de Valk J. , van der Plas H. C. 
Published: September 2010

AbstractEvidence is presented that the conversion of 4‐bromo‐6‐phenylpyrimidine into 4‐amino‐6‐phenylpyrimidine by treatment with potassium amide in liquid ammonia at ‐75° occurs to the extent of about 80% according to a mechanism involving an open‐chain intermediate.
Activity coefficients of single ions. II: The difference between the standard chemical potentials of single ions in N‐methylformamide and water at 25°C
Authors: de Ligny C. L. , Denessen H. J. M. , Alfenaar M. 
Published: September 2010

AbstractThe method for the estimation of activity coefficients of single ions, developed by Alfenaar and De Ligny, was improved by incorporating in it ideas of Buckingham and of Muirhead‐Gould and Laidler.The modified method was successfully applied to the transfer of ions from water to N‐methylformamide.A crucial point in the application of this method is the availability of data on large ions. In the present work, data on the ferricinium ion, the tetramethyl‐ammonium ion, and the tetrapropylammonium ion were used, in addition to data on alkali metal, halide, the perchlorate, and the perrhenate ions.From the difference between the standard chemical potentials of the chloride ion in water and N‐ methylformamide, obtained in this investigation, the corresponding difference between the standard real potentials, determined by Case and Parsons, and the surface potential of water, the surface potential of N‐ methyl‐formamide was determined.
Hindered internal rotation in carbamates: An NMR study of the conformations of alkyl and arylN‐(alkylsulfonylmethyl)‐N‐methylcarbamates and arylN‐(arylsulfonylmethyl)‐N‐methylcarbamates
Authors: van Est‐Stammer R. , Engberts J. B. F. N. 
Published: September 2010

AbstractDifferences in intramolecular shielding of the ester alkyl protons between rotamers in a series of alkylN‐(arylsulfonylmethyl)‐N‐methylcarbamates were used as an unambiguous tool for rotamer signal assignment. On the basis of these results, aromatic solvent‐induced shifts (Δv) and trifluoroacetic acid (TFA)‐induced shifts (Δv) were found to be applicable as criteria for signal assignment of carbamate rotamers. Using these criteria, the conformations of previously unreported alkyl and arylN‐(alkylsulfonylmethyl)‐N‐methylcarbamates and arylN‐(arylsulfonylmethyl)‐N‐methylcarbamates have been determined. The rotamer population (E/Zratio) is discussed in terms of the structures of these carbamates. The smaller Δvvalues of carbamates as compared with carboxamides are primarily the result of the lower ground state basicity of the carbamate function and of the presence of more than one site of comparable acceptor strength. This conclusion is supported by an IR spectroscopic study of hydrogen bond adduct formation between phenol and a series ofN, N‐disubstituted carbamates.
Cobalticenium salts. II. Synthesis and structure of cobalticenium (triphenylphosphine)trihalogenocobaltates(II), [Cp2Co][Co(PPh3)X3] (X = Cl,Br,I)
Authors: van den Akker M. , Olthof Roeli , van Bolhuis F. , Jellinek F. 
Published: September 2010

AbstractThe synthesis of cobalticenium (triphenylphosphine)trihalogenocobaltates(II), [Cp2‐Co][Co(PPh3)X3] (X = Cl,Br,I), which were first found as by‐products in the reaction of cobaltocene with triphenylphosphonium halides, is reported. The nature of the green complexes was derived from analytical and spectroscopic data and confirmed by X‐ray analysis of the iodo complex. Oxidation of solutions of the iodo complex by oxygen gives the compound [Cp2Co][Co(OPPh3)I3].[Cp2Co][Co(PPh3)I3] is cubic (a = 18.272 Å), space group Pa3, with eight formula units in the cell. The structure consists of discrete ions [Ph3PCoI3]− and [CpCoCp]+, both lying on a threefold axis. The apparent threefold symmetry of the cobalticenium cations is due to disorder of the π‐cyclopentadienyl ligands about the threefold axes. The substituents of P and Co in the [Ph3PCoI3]− anion are in staggered configuration; the metal atom is approximately tetrahedrally surrounded by 3 I (at 2.557 Å) and 1 P (at 2.368 Å), the latter distance being larger than in other phosphinecobalt complexes.
The coordination chemistry of nonamethylimidodiphosphoramide: Part II. Compounds containing solvated metal ions
Authors: de Bolster M. W. G. , Groeneveld W. L. 
Published: September 2010

AbstractA number of compounds of the general formula M(NIPA)n(anion)m is reported, in which M = Mg,Ca,Sr,Ba,Al,Cr,Fe and In; NIPA = nonamethylimidodiphosphoramide { = [(CH3)2N]2P(O)N(CH3)P(O)[N(CH3)2]2 }, n = 1‐3, m = 2,3 and the anions are BF−4, Cl−, Br−, I−, NO−3 and NCS−.The compounds are characterized by chemical analyses and physical measurements.With the aid of infrared and ligand‐field spectra in combination with X‐ray powder patterns octahedrally coordinated metal ions are found in all compounds.The ligand is shown, by means of infrared spectroscopy, to coordinate via the oxygen lone pair electrons to the metal ions investigated.Metal‐ligand stretching frequencies are observed in the 700 − 450 cm−1 region for the trivalent metal compounds. The absence of these bands in the spectra of the bivalent metal complexes is explained in terms of the high ionic character of the metal‐ligand bond in these compounds.
Complexes of N,N‐Dialkyldithiocarbamate esters with mercury(II) dihalides
Authors: Brinkhoff H. C. , Dautzenberg J. M. A. 
Published: September 2010

AbstractReaction between mercury(II) dihalides (HgX2) with N,N‐dialkyldithiocarbamate esters [R ′(R2dtc)] in organic solvents has resulted in the synthesis of complexes with the formula HgX2[R ′(R2dtc)J. On the basis of several physical measurements, including IR, Raman and PMR spectra, it is suggested that in these complexes mercury is three‐co‐ordinated by two halogens and one sulfur atom.
Formation of dialkylthiophenes by thermolysis of di(1‐alkenyl) disulfides and alkyl 1‐propenyl disulfides
Authors: Boelens H. , Brandsma L. 
Published: September 2010

Abstract3,4‐Dialkylthiophenes are formed in good yields by heating di(1‐alkenyl) disulfides at 150‐200° in the presence of potassium hydrogen sulfate. Thermolysis of alkyl 1‐propenyl disulfides gives mixtures of sulfur‐containing compounds, consisting mainly of 3,4‐dimethylthiophene, dialkyl disulfide, alkyl and 1‐alkenyl monosulfides, and dialkyl trisulfide.
Heterocylic synthesis via 1‐amino‐3‐oxo‐1‐cyclohexene
Authors: Dubas‐Sluyter M. A. T. , Speckamp W. N. , Huisman H. O. 
Published: September 2010

Abstract2,5‐Dioxo‐1,2,5,6,7,8‐hexahydroquinoline 2 is formed upon condensation of methyl propiolate with ketone 1 in DMF as solvent. On the other hand, reaction 1 with propargylic acid led to 1,8‐dioxo‐perhydroacridine 4b as the sole isolable product.
The molecular and crystal structure of dipotassium mesitylene‐disulfonate dihydrate
Authors: Meester Marthie A. M. , Schenk H. 
Published: September 2010

AbstractDipotassium mesitylenedisulfonate dihydrate crystallizes in monoclinic needles, space group P21/c, cell constants a = 7.341, b = 12.330, c = 15.934 Å, β = 94.60°, Z = 4. The overcrowding of substituents in the mesitylenedisulfonic group does not affect the bond lengths, but changes the bond angles, planarity and geometry of the molecule significantly.
CIS‐ and trans‐1‐bromopropene vibrational assignment; coriolis interaction
Authors: Elst R. , v.d. Berg G. C. , Oskam A. 
Published: September 2010

AbstractInfrared gas‐phase spectra and Raman liquid‐phase spectra are recorded of cis‐ and trans‐1‐bromopropene. A vibrational assignment is reported for both isomers.Some vibration‐rotational bands of the trans isomer can be analyzed in terms of Coriolis interaction; three Coriolis coupling constants are calculated.
The nitration of mono‐alkylbenzenes conformational analysis and steric hindrance: Part IV: tertiary alkyl‐ and cycloalkylbenzenes
Authors: Baas J. M. A. , Wepster B. M. 
Published: September 2010

AbstractThe isomer distributions and the partial rate factors for the nitration of eight tertiary alkylbenzenes and five tertiary cycloalkylbenzenes have been determined. The fm values for the tertiary alkylbenzenes are greater than for the primary and secondary compounds. The fp value for (1‐methylcyclopropyl)‐benzene shows that the pseudo conjugation between the cyclopropyl group and the benzene ring is disturbed. The steric hindrance of the nitration in the ortho‐positions increases greatly as the branching of the alkyl groups increases.
The photorearrangement of a phenyl substituted diaryl ether
Authors: Hageman H. J. , Huysmans W. G. B. 
Published: September 2010

AbstractUV irradiation of 4‐(2,6‐diphenylphenoxy)‐2,6‐diphenylanisole (I, R=Ph) affords a single product resulting from cleavage of the central (aromatic) ether bond and subsequent rearrangement to a pendant (ortho) phenyl group.
C‐nitroso compounds. Part XXIII: Cis/trans‐isomerisation of aliphatic azodioxy compounds (dimeric nitrosoalkanes)
Authors: Wajer Th. A. J. W. , de Boer Th. J. 
Published: September 2010

AbstractA mechanistic and kinetic study has been made of the cis/trans‐isomerisation of cis‐azodioxycyclohexane and cis‐azodioxymethane in acetonitrile at temperatures, varying from 0‐60°. Cross‐over and trapping experiments show that the isomerisation does not proceed by rotation around the NN bond but exclusively via dissociation and recombination of free monomer molecules. Kinetic data indicate that the monomer molecules dimerize at low temperature by kinetic control chiefly to the cis‐isomer. At elevated temperatures the thermo‐dynamically more stable trans‐isomer is formed. Activation parameters show that the formation of the cis‐isomer from two monomer molecules is controlled by entropy rather than by enthalpy factors.
Aromatic sulfonation. Part 33: Effects of sulfonic acid addenda upon the isomer distribution in the sulfonation of toluene with sulfuric acid
Authors: Ris C. , Cerfontain H. 
Published: September 2010

AbstractThe isomer distribution in the sulfonation of toluene with 95.8% H2SO4 at 25° in the presence of some sulfonic acids and other addenda was determined. All the addenda studied effect a decrease in the degree of ortho‐substitution. Most effective are p‐t‐butylbenzenesulfonic acid, methyl trimethylphenylammonium sulfate and nitrobenzene. The effect of methanesulfonic acid is very small, that of water and of sodium bisulfate almost negligible. The degree of meta‐substitution is small and is unaffected by the addenda.The variations in the isomer distribution are discussed in terms of changes in the solvation of the reactants and of the transition states.
Osmium(II) and Ruthenium(II) complexes of tricyclohexylphosphine
Authors: Moers F. G. , Langhout J. P. 
Published: September 2010

AbstractThe preparation of tricyclohexylphosphine complexes of osmium and ruthenium is reported. The reaction of K2OsCl6 or hydrated RuCl3 with tricyclohexylphosphine (PCy3) in 2‐methoxyethanol leads to the complexes MHCl(CO) (PCy3)2 with M = Os or Ru. Hydrogen‐deuterium exchange of PCy3 was observed in these complexes on reaction with deuterium gas and in the complexes prepared with deuteriated ethanol. Addition of pyridine (py) gives complexes of the formula MHCl(CO) (PCy3)2(py). Phosphonium compounds containing iron(III) and osmium(IV) halides as anions were prepared and characterised.
The synthesis of enamines and ketimines using molecular sieves
Authors: Roelofsen D. P. , van Bekkum H. 
Published: September 2010

AbstractThe synthesis of enamines and ketimines from the corresponding carbonyl compound and amine in high yield at room temperature is described using a commercial silica‐alumina cracking catalyst to catalyze the reaction and a suspended molecular sieve type A to shift the equilibrium. The mixture of molecular sieve and silica‐alumina can be successfully regenerated.Different solvents, catalysts and molecular sieves have been tested. The combination of cyclohexane, silica‐alumina and molecular sieve type 5A gives the best results; besides the pure powder, pellets type 5A can also be used in combination with silica‐alumina catalyst.The moderate catalytic effect of pellets as such, as reported in the literature, has been traced down to the binding agent present in pelletized material.
The coordination chemistry of nonamethylimidodiphosphoramide: Part III. Compounds of nickel(II) iodide
Authors: de Bolster M. W. G. , Groeneveld W. L. 
Published: September 2010

AbstractComplex‐formation between the ligand nonamethylimidodiphosphoramide (NIPA) and nickel(II) iodide has been investigated.By varying the solvent and the metal salt to ligand ratio, three compounds could be isolated, that were identified by chemical analysis and physical measurements as [Ni(NIPA)3]2+[I−]2; [Ni(NIPA)2I2] and [Ni(NIPA)3]2+ [NiI4]2−.The compound [Ni(NIPA)2I2] appeared to be unstable in the solid state; its decomposition was studied and a possible mechanism is given.
The conformation of non‐aromatic ring compounds 73: The molecular and crystal structure of β‐chloroglutaric anhydride
Authors: Koer F. J. , de Kok A. J. , Romers C. 
Published: September 2010

AbstractCrystals of β‐chloroglutaric anhydride are monoclinic. The space group is C2/c, the unit cell constants are a = 23.63, b = 6.07, c = 20.83 Å, β = 122.1° and Z = 16. Three‐dimensional photographic X‐ray diffraction data were collected at room temperature. The structure was solved with a minimum function and refined using the least‐squares method.The six‐membered ring has a sofa conformation, the β carbon atom being 0.63 Å out of the plane of the other ring atoms. The—CO‐O‐CO moiety is coplanar with the ring atoms, the CCl bond has axial orientation. A slight difference in conformation between the two crystallographically independent molecules is observed.
Chemistry of acetylenic ethers 96: Reactions of 1,3‐dialkoxy‐1‐alkynes with organolithium compounds synthesis of 1‐substituted allenyl ethers and of conjugated dienyl ethers
Authors: Braams J. F. H. , Montijn P. P. , Bos H. J. T. 
Published: September 2010

AbstractReaction of 1,3‐dialkoxy‐1‐alkynes R2R3C(OR1)C  COR (I) (R and R1are alkyl, R2and R3are H or alkyl) with organolithium compounds R4Li affords a mixture of 1‐substituted allenyl ethers R2R3C  C  C(R4)OR (II) (major product) and 2‐alkynyl ethers of the type R2R3C(OR1)C  CR4(III). The formation of 2‐alkynyl ethers was not observed when R2 R3 H.The ratios allenyl ether/2‐alkynyl ether depend on R4Li, the leaving groups OR1and OR, and the solvent.For preparative conversions to allenyl ethers a 1:1 mixture of ether and 1,2‐dimethoxyethane is suitable as solvent.By acid catalyzed isomerization the 1‐alkylated allenyl ethers II are converted smoothly and quantitatively into conjugated alkoxydienes (IV), especially when also R2and R3are alkyl groups.
Synthesis of 2‐acyl‐2‐thiazolines
Authors: Doornbos T. , Peer H. G. 
Published: September 2010

Abstract2‐Acyl‐2‐thiazolines were prepared by condensation of vic‐aminothiols with 2,2‐dialkoxyalkanenitriles and hydrolysis of the resulting 2‐(1,1‐dialkoxyalkyl)‐2‐thiazolines. A similar route via 2‐(1‐hydroxyiminoalkyl)‐2‐thiazolines also proved successful.
Properties of cyclodextrins, Part VIII: Determination of the composition of inclusion complexes of hexane and 2,3‐dimethylbutane with cyclodextrin derivatives in aqueous solution
Authors: Lammers J. N. J. J. , van Diemen A. J. G. 
Published: September 2010

AbstractThe composition of inclusion complexes of cyclodextrin derivatives with hexane and 2,3‐dimethylbutane in aqueous solution is determined from the values of the complex association constants ‐ as determined in part VII of this series ‐ together with the values of the association constants measured at varying vapour pressures.It has been found that the carboxymethyl ether and sulfonatopropyl ether of α‐cyclodextrin as well as the soluble α‐epichlorohydrin resin, form 1:1 complexes with both hexane and 2,3‐dimethylbutane. The carboxymethyl ether and sulfonatopropylether of β‐cyclodextrin form 1:1 complexes with 2,3‐dimethylbutane and mainly 1:1 complexes with hexane, while a complex in which two hexane molecules combine with one cyclodextrin molecule (2:1 complex) may be present. The soluble β‐epichlorohydrin resin forms 1:1 complexes with both hexane and 2,3‐dimethylbutane, presumably mixed with 2:1 complexes.
Functionalized enamines. Part XII: Influence of base‐component in the reaction of β‐tetralone enamines with carbenes
Authors: Pandit U. K. , de Graaf S. A. G. , Braams C. T. , Raaphorst J. S. T. 
Published: September 2010

AbstractEnamines derived from β‐tetralone and morpholine and dimethylamine (Ia,b), react with carbenes IIa,b to give 1:1 adducts IIIa,b and ring‐insertion products IVa,b, respectively. The reaction of pyrrolidine enamine Ic with the carbenes leads to the formation of new types of products which have been identified as VI and VII. Possible mechanisms for the formation of the reaction products are presented.
A crystal‐field study of the ESR and UV spectra in relation to the structure of complexes of titanium(III) with chlorine and acetonitrile
Authors: Ostendorf H. K. 
Published: September 2010

AbstractFrom the ESR and UV spectra the complex TiCl3(CH3CN)3 is shown, by means of the crystal‐field theory, to have the configuration with C2v symmetry rather than that with C3v symmetry. The ESR and UV spectra of the ion [TiCl2(CH3CN)4]+, formed by adding a chlorine ion acceptor (e.g. TiCl4, SnCl4, AlCl3, FeCl3) to a solution of anhydrous TiCl3 in acetonitrile, could be calculated from the crystal‐field parameters, which were determined from the spectra of TiCl3(CH3CN)3.
The nitration of mono‐alkylbenzenes conformational analysis and steric hindrance: Part V: Mechanistic aspects
Authors: Baas J. M. A. , Wepster B. M. 
Published: September 2010

AbstractThe ½ ortho/para ratios for the nitration of twelve alkylbenzenes with nitric acid and acetic anhydride in nitromethane equal those for the nitration with nitric acid and sulfuric acid in nitromethane. This proves also that under the first‐mentioned conditions the nitronium ion is the effective nitrating agent involved in the product‐determining transition states.
Ring transformations in reactions of heterocyclic halogeno compounds with nucleophtiles (XXIV): Study of the mechanisms of the conversion of 2‐halogenoquinoxalines into 2‐aminoquinoxalines and benzimidazole by potassium amide in liquid ammonia
Authors: Lont P. J. , van der Plas H. C. 
Published: September 2010

AbstractTreatment of 2‐halogenoquinoxalines and 3‐substituted 2‐halogenoquinoxalines with potassium amide in liquid ammonia yields the corresponding 2‐aminoquinoxalines and benzimidazole. It was found ‐ using 2‐chloro‐[2‐ 14C]quinoxaline ‐ that the ring contraction does not involve a benzotriazepine derivative as intermediate and that the animation occurs via an AE‐mechanism. In the case of 2‐fluoroquinoxaline, there are indications that the amination goes partially via an addition‐abnormal‐elimination (EAa mechanism.