bluuebunny/crossref_metadata_2025_split huggingface dataset:
Complexes with ligands containing nitrile groups.: Part VIII. Organic nitriles as ligand
Authors: Zuur A. P. , Reintjes A. H. L. , Groeneveld W. L. 
Published: September 2010

AbstractA series of complexes of the type M2+(L)6(SbCl6−)2 is reported, in which M is Mg(II), Co(II), Ni(II), Cu(II) and Zn(II), and L (Ligand) is butyronitrile, isobutyronitrile, trimethylacetonitrile and benzonitrile. Ligand Field spectra have been investigated for the Co(II), Ni(II) and Cu(II) complexes, values for Dq and B are reported and compared with the values for methyl cyanide. In the infrared region shifts of the CN stretching frequencies are discussed.
The hydrogenation of benzene over supported platinum, palladium and nickel catalysts
Authors: Aben P. C. , Platteeuw J. C. , Stouthamer B. 
Published: September 2010

AbstractThe activity for the hydrogenation of benzene has been studied for supported platinum, palladium and nickel as a function of metal particle size and carrier. Metal crystallite sizes varied between 10 and 400 Å and silica, alumina, silica‐alumina and silica‐magnesia were used as supports. It has been found that the activity per exposed metal atom is independent of the metal crystallite size or of the support used. The hydrogenation activities per exposed metal atom at a temperature of 100°C and a hydrogen pressure of 5.6 atm are ranked as follows:kpt: kNi: kPd = 18:7:1.It is further shown that the activation energies observed experimentally for the various catalysts at a given set of conditions are predicted with a high degree of accuracy with the aid of the theory of absolute reaction rates, based on a resonable estimate of the number of exposed metal atoms per hydrogenation site.
Correlations between catalytic and thermodynamic parameters of transition metal Oxides
Authors: Sachtler W. M. H. , Dorgelo G. J. H. , Fahrenfort J. , Voorhoeve R. J. H. 
Published: September 2010

AbstractThe oxidation of benzaldehyde to benzoic acid with V2O5, SnO2‐promoted V2O5 and MnO2 as catalysts has been investigated. The reaction mechanism includes the following steps: dissociative chemisorption of benzaldehyde, yielding an asymmetric covalent benzoate complex with one oxygen atom of the sufrace, atomic rearrangement to the symmetric benzoate ion, desorption of benzoic acid and reoxidation of the catalyst surface by adsorption of oxygen. The activity of the oxides is found to be related to their ability to release oxygen. An antibatic relation between the Gibbs free energy of oxygen release and the catalytic activity is demonstrated. The action of the tin promoter in the mixed oxide catalyst is due to the loosening of the metal‐oxygen bond. A parallelism is suggested between the catalytic selectivity and the differential increase of the enthalpy of oxygen release with increasing degree of reduction.
Studies on cyclohexane derivatives. Part VIII: Preparation and mass spectra of the seven t‐butylcyclohexanecarboxylic acids
Authors: van Bekkum H. , van de Graaf B. , van Minnen‐Pathuis G. , Peters J. A. , Wepster B. M. 
Published: September 2010

Abstract1‐t‐Butylcyclohexanecarboxylic acid (1) has been synthesized from t‐butyl‐cyclohexanols as well as from 2‐(1‐methylcyclohexyl)‐2‐propanol by the Koch ‐Haaf carboxylation. A side product in these preparations is 2‐methyl‐2‐(1‐methylcyclohexyl)propionic acid (5).Details are given for the preparation of the cis‐ and trans‐isomers of 2‐, 3‐and 4‐t‐butylcyclohexanecarboxylic acid (cis‐ and trans‐2, 3 and 4) starting from the corresponding t‐butylbenzoic acids.The t‐butylbenzoic acids and their methyl esters have been hydrogenated over transition metal catalysts at 25°. Palladium differs from platinum, rhodium and ruthenium by, in all cases, giving in excess the most stable isomer. In the hydrogenation of 2‐t‐butylbenzoic acid over rhodium desorbed 6‐t‐butyl‐1‐cyclohexene‐1‐carboxylic acid is shown to be the main source of the trans‐2 formed.The mass spectra of 1 − 4 are presented and discussed. The mode of fragmentation of cis‐4 and cis‐3 was found to differ in a characteristic way from that of their trans‐isomers.
Isomerization, cracking and dehydrogenation of protonated mesityl oxide
Authors: Brouwer D. M. , van Doorn J. A. 
Published: September 2010

AbstractProtonated mesityl oxide (1,3,3‐trimethyl‐1‐hydroxyallyl cation, 1) in strong acids has been found to give three reactions, resulting in a large variety of products depending on the acid used as the solvent.(1) Isomerization, followed by cyclization, gives the 2,5‐dimethyltetrahydrofuryl cation, which is about 5 × 103 times stabler than 1. The isomerization, which proceeds via intermediate dications, is acid‐catalysed; its rate decreases strongly in the order 1: 1 HF‐SbF5 〉〉 9: 1 HF‐SbF5 〉 1: 1 FSO3H‐SbF5 〉〉〉 5: 1 FSO3H‐SbF5.(2) In FSO3H‐SbF5, dehydrogenation with subsequent ring closure to give the 2,4‐dihydrofuryl cation.(3) Cracking produces the acetyl cation and isobutene, which are formed by β‐scission of C‐protonated mesityl oxide. The isobutene fragment reacts further to give, depending on the acid and the rate at which it is formed, t‐butyl cation, or the disulfonic acids of isobutene, or products thereof, and alkylcyclopentenyl ions.Rate constants of the three reactions in the different solvents have been measured. The 1‐ethyl‐3,3‐dimethyl‐1‐hydroxyallyl cation (2) reacts in a similar way, but different product selectivities are obtained.
Preparation and nmr spectra of 3‐alken‐1‐Ynylamines and 1,3,5‐Trienylamines
Authors: Galesloot W. G. , de Bie M. J. A. , Brandsma L. , Arens J. F. 
Published: September 2010

AbstractCompounds of the type H2CCR1‐CC‐CH2‐N(C2H5)2(I), when treated with potassiumtert‐butoxide in dimethyl sulfoxide are converted predominantly into the 3‐alken‐1‐ynylamines H3C‐CR1CH‐CC‐N(C2H5)2(IV), while those of the type R2CH2‐CR3CH‐CC‐CH2‐N(C2H5)2(VI) yield 1,3,5‐trienylamines R2CHCR3‐CHCH‐CHCH‐N(C2H5)2(VIII). A discussion of the NMR parameters of the 1,3,5‐trienylamines is given.
Cleavage of α,β‐unsaturated Sulfides, Alkyl Cycloalkyl Sulfides AND Cycloalkanone Dialkyl Dithioacetals with Alkali Metals in liquid Ammonia
Authors: Brandsma L. 
Published: September 2010

AbstractUnsaturated thiols having the system ‐C=C‐SH can be obtained by cleavage of the corresponding alkyl sulfides ‐C=C‐SR with alkali metals in liquid ammonia and acid hydrolysis after evaporation of the ammonia. Cycloalkanone dimethyl dithioacetals (CH2)nC(SCH3)2 give cycloalkanethiols (CH2)nC(H)(SH) (n = 2, 4, 5, 6) on treatment with 4 equivalents of alkali metal. Alkyl cycloalkyl sulfides (CH2)nC(H)(SR) (R = CH3 or C2H5) have been obtained by adding 2 equivalents of alkali metal to the dithioacetals (CH2)nC(SR)2. The cleavage reactions mentioned proceed with good to almost quantitative yields. The conversion of cycloalkyl ethyl sulfides and cycloalkanone diethyl dithioacetals with alkali metals is suitable for the preparation of the three‐ and six‐membered ring thiols but proceeds unsatisfactorily in the case of the five‐ and seven‐membered rings, cleavage between the ring and sulfur being the main reaction.
The photolysis of Cyclopropanecarbaldehyde at 254 nm in the presence of Neopentane, Cyclohexane and 2,3‐Dimethylbutane
Authors: Overwater J. J. I. , Cerfontain H. 
Published: September 2010

AbstractCyclopropanecarbaldehyde has been photolyzed in the gas phase with light of 254 nm, in the presence of each of the following hydrocarbons: neopentane, cyclohexane and 2,3‐dimethylbutane (biisopropyl). With increasing total pressure the quantum yields of the gaseous products carbon monoxide, ethene, propene and cyclopropane decrease. The decrease in the quantum yields of propene and ethene is explained in terms of collisional deactivation of vibration‐ally excited singlet excited cyclopropanecarbaldehyde.The decrease in the quantum yield of cyclopropane with increasing total pressure is explained partly in terms of collisional deactivation of vibrationally excited triplet cyclopropanecarbaldehyde, and partly in terms of hydrogen abstraction by cyclopropyl radicals from the added hydrocarbon. With 2,3‐dimethylbutane as addendum the two mechanisms are of about equal importance, whereas with neopentane or cyclohexane the former mechanism is thought to predominate.
Conformation of non‐aromatic ring compounds. Part 64. NMR spectra and dipole moments of 2‐alkylthiotetrahydropyrans
Authors: de Hoog A. J. , Havinga E. 
Published: September 2010

AbstractThe conformational equilibrium in six 2‐alkylthiotetrahydropyrans is studied by means of dipole moment measurements and NMR spectroscopy. In these compounds the anomeric alkylthio group has, in general, a slight preference for the axial position. From the occurrence of a linear relationship between the squares of the dipole moments and vicinal coupling constants the conclusion follows that only one axial and one or two equatorial conformers are present in the equilibrium. A comparison is made with the conformation of the anomeric alkoxy group.
HO data and other properties of some hydrogen fluoride based solvents
Authors: Dalllnga G. , Gaaf J. , Mackor E. L. 
Published: September 2010

AbstractThe properties of a new acidic solvent system consisting of equimolar amounts of anhydrous hydrogen fluoride and oxygen‐containing components, such as alcohols, ether or acetic acid, are described. Through the addition of BF3 Hammett's acidity function, HO, can be varied between ‐ 1.4 and ‐ 7. These acids proved to be particularly useful for the study of the photochemistry of aromatic hydrocarbons.Measurements of the Hammett function, HO, are reported for hydrogen fluoride containing sodium fluoride, water, ethanol and BF3.
An efficient nonenzymatic conversion of benzylpenicillin to 6‐aminopenicillanic acid
Authors: Weissenburger H. W. O. , van der Hoeven M. G. 
Published: September 2010

AbstractAn efficient procedure for the chemical conversion of benzylpenicillin to 6‐aminopenicillanic acid is described. The selective cleavage of the amide bond has been accomplished by treating the silyl ester of benzylpenicillin consecutively with phosphorus pentachloride, n‐butanol and water at low temperatures.
Association constants of the hexamethylbenzene‐1,3,5‐trinitrobenzene complex in various saturated hydrocarbon solvents
Authors: Foreman M. I. , Foster R. 
Published: September 2010

AbstractFrom NMR chemical shift measurements, it is shown that the degree of association for the interaction between hexamethylbenzene and 1,3,5‐trinitro benzene in various saturated hydrocarbon solvents is dependent on the particular solvent, irrespective of the particular concentration scale used.
The alkylation of imine anions formation of enamines
Authors: Heiszwolf G. J. , Kloosterziel H. 
Published: September 2010

AbstractThe ambident anions derived from a number of imines have been alkylated using a variety of solvents and alkylating agents. Under reactive conditions enamines (N‐alkylation) are formed as the main products instead of the usually observed homologous imines (C‐alkylation). The influence of the type of imine, solvent and alkylating agent on the mode of alkylation is discussed.
Functionalized enamines. Part XI. Steric effects in α‐tetralone enamines
Authors: van der Vlugt F. A. , Verhoeven J. W. , Pandit U. K. 
Published: September 2010

AbstractSynthesis of enamines 2a‐f, derived from α‐tetralones 1a, 1b, is described. Steric effects in the formation of these enamines and in the spectral properties of the corresponding 2‐substituted derivatives are discussed.
Koch‐Haaf carboxylations of tert‐alkyl substituted cycloalkanols
Authors: Peters J.A. , van Bekkum H. 
Published: September 2010

AbstractContrary to literature data 1‐isopropylcyclohexanol afforded both 1‐isopropylcyclohexanecarboxylic acid and 2‐cyclohexyl‐2‐methylpropanoic acid upon carboxylation by the method of Koch.The Koch‐Haaf carboxylation of a number of tert‐alkyl substituted cycloalkane derivatives has been studied. Side reactions were suppressed by using the Haaf conditions with slow stirring of the reaction mixture.tert‐Butylcyclohexanols afforded 1‐tert‐butylcyclohexanecarboxylic acid accompanied by 2‐methyl‐2‐(1‐methylcyclohexyl)propanoic acid. In the Koch‐Haaf reaction of 3‐tert‐butylcyclopentanol and 4‐tert‐butylcycloheptanol more complex rearrangements occurred. The main products were 1,2,2‐trimethylcyclohexanecarboxylic acid and 2‐cyclohexyl‐2,3‐dimethylbutanoic acid, respectively.From the composition of the reaction products conclusions were drawn concerning the mechanisms of the rearrangements involved in these reactions. In some of the reactions protonated cyclopropane rings are proposed as intermediates.
The chemistry and fungicidal and phytotoxic properties of heterocyclic sulfonyl‐, sulfinyl‐, and thio‐methyl thiocyanates
Authors: Willems A.G.M. , Tempel A. , Hamminga D. , Stork B. 
Published: September 2010

AbstractThe synthesis of 38 compounds with structure RSOn‐CH2‐SCN, in which R is a heterocyclic radical and n = 0, 1, or 2, is described and their fungicidal and phytotoxic activities are discussed.
Pyrazoles and imidazoles as ligands. Part V : Infrared and Raman spectra of 3(5)‐methylpyrazole coordinated to metal(II) ions
Authors: Reedijk J. 
Published: September 2010

AbstractInfrared spectra (4000‐150 cm−1) and Raman spectra (4000‐50 cm−1) of 3(5)‐methylpyrazole (MPZ) and coordination compounds of formula M2+(MPZ)n(anion)2− have been investigated.Assignments are proposed for the free‐ligand normal modes of vibration and for the metal‐ligand vibrations. The shift in some of the ligand vibrations upon coordination to metal salts is discussed, and interpreted on the basis of differences in binding properties of the several metal ions and anions.The N‐H vibrations of MPZ especially appear to be strongly dependent upon the hydrogen‐bonding properties of the anions present in the coordination compounds. The strongest hydrogen bond is found with Cl− anions, followed by Br−, I−, NO3−, BF4−, whereas the ClO4− anions appear to be scarcely hydrogen bonded with the MPZ ligands in the coordination compounds.The metal‐ligand vibrations in the complexes appear to be dependent on the metal ion, and follow the usual Irving‐Williams sequence of metal ions.
Aromatic sulfonation 28: Degree ofortho‐substitution in the sulfonation of toluene with sulfur trioxide, methanepyrosulfonic acid and fuming sulfuric acid. A mechanistic picture
Authors: Koeberg‐Telder A. , Cerfontain H. 
Published: September 2010

AbstractThe reaction of neat toluene with a number of different sulfonation reagents at 25° has been studied. With sulfur trioxide vapour as reagent, the reaction leads to monosulfonation only. Theo/(o + m + p)ratio varies with the degree of toluene conversion, the limiting values at zero and high conversion being 0.34 ± 0.03 and 0.11 ± 0.01, respectively. The former value is ascribed to the sulfonation of toluene with sulfur trioxide, the latter to sulfonation in the acid phase with toluenepyrosulfonic acid as the sulfonating entity.The heterogeneous reaction of toluene with a deficient amount of a matured mixture of methanesulfonic acid and sulfur trioxide ‐ i.e. with a methanepyrosulfonic acid reagent — leads to monosulfonation only. Theo/(o + m + p)ratio varies from 0.15 ± 0.01 at zero toluene and zero time conversion to 0.11 ± 0.01 at high toluene conversion. The former value is ascribed to sulfonation in the acid phase of dissolved toluene by methanepyrosylfonic acid, the latter to that by both toluene‐ and methane‐pyrosulfonic acids.Heterogeneous sulfonation with a deficient amount of fuming sulfuric acid takes place mainly ( ∼97 %) in the acid phase. Sulfonation in the toluene phase leads to monosulfonic acids only with 41 ± 2 % ofortho‐substitution. Sulfonation in the sulfuric acid phase yields monosulfonic acids and, at the higher sulfuric acid concentrations, also toluene‐2,4‐disulfonic acid. The degree ofortho‐substitution for sulfonation in the acid phase at 25° changes from 48.5 to 40 % on varying the acid concentration from 100.0 to 106.4% H2SO4.
Complexes with ligands containing the carbonyl group. Part IV Metal(II) Butanone, Acetophenone, and Chloroacetone Solvates
Authors: Driessen W.L. , Groeneveld W.L. 
Published: September 2010

AbstractTwenty‐three new coordination compounds are reported with butanone, acetophenone and chloroacetone as the ligands, viz. M(C2H5COCH3)6(InCl4)2, M(C6H5COCH3)6(InCl4)2, M(ClCH2COCH3)6(InCl4)2and M(CICH2COCH3)6‐(FeCl4)2where M is Mg, Mn, Fe, Co, Ni, and Zn.In the complexes the carbonyl stretching vibration is shifted to lower frequencies with regard to this vibration in the free ligands, the magnitudes of the shifts are metal‐dependent in the Irving‐Williams order. Other ligand vibrations also shift on complexing.The presence of octahedral species M(O)62+in the solid compounds was indicated by the ligand field spectra of the Fe(II), Co(II) and Ni(II) compounds. Values of Dq and B for the Co(II) and Ni(II) compounds are reported.
Phase transitions in copper chalcogenides: I. The copper‐selenium system
Authors: Stevels A.L.N. , Jellinek F. 
Published: September 2010

AbstractThe thermal behaviour of copper selenides up to about 400°C has been studied by X‐ray diffraction at continuously variable temperature and by differential.The thermal behaviour of copper selenides up to about 400°C has been studied orthorhombic (pseudo‐rhombohedral) with a = 4.118, b = 2 × 7.032, c = 20.381 Å at 20°. The homogeneity range of the f.c.c. phase Cu2‐xSe was found as 0.15 ≤ × ≤ 0.20 at 20°; the atomic arrangement in Cu1,80Se was determined. A superstructure of this phase is found below − 115°. CuSe is hexagonal (CuS‐type) above 120° (a = 3.976. c = 17.243 Å at 140°), orthorhombic between 120° and about 50° (a = 3.949. b = 6.935, c = 17.20 Å at 60°), and has a hexagonal superstructure at lower temperatures (a = 14.20. c = 17.26 Å at 20°). The literature data on Cu3Se2 and CuSe2 were confirmed.
Synthesis of 2,5‐substituted 4‐imidazolidinones
Authors: Wiering P.G. , Steinberg H. 
Published: September 2010

Abstractα‐Alkylidenimino‐carboxylic esters can be prepared in 60‐95% yield by condensation of α‐aminocarboxylic esters with aldehydes. In the presence of ammonia these condensation products undergo an intramolecular cyclisation to give 2,5‐substituted 4‐imidazolidinones in 70‐95% yields.
Palladium‐catalysed reactions of unsaturated compounds in non‐aqueous solvents: Reaction of conjugated and cumulated diolefins with π‐allylpalladium halides
Authors: Medema D. , van Helden R. 
Published: September 2010

AbstractInteraction of π‐allylpalladium halides with conjugated dienes leads to new π‐allylpalladium complexes via addition of the allyl fragment to the diene molecule. We succeeded in isolating the intermediate complexes in high yield and determining their structures. With conjugated dienes the addition takes place at the most substituted carbon atom in the π‐allyl fragment, contrary to what happens in the reaction with CO and allene. Substituents in the π‐allyl group and the other ligands bound to the metal prove to have a strong influence on the rate. For the bridging ligand the rate decreases in the order Cl > Br > CNS > I. For α‐or β‐substituted π‐allyl the order is Cl > COOR >> H > CH3. In combination with a kinetic investigation, the present study has provided a mechanism which accounts for the stereospecificity of the reaction and the accelerating influence of electron‐withdrawing groups.The results demonstrate the importance of π‐allyl transition‐metal intermediates in e.g. oligo‐ and polymerization of dienes. Repetition of the above‐described process leads with π‐allyl‐palladium halides to low‐molecular weight 1,2‐polymers of butadiene.
Isomerism of benzoquinone monoximes: XV The crystal structure of 2,6‐di‐tert‐butyl‐4‐(p‐bromophenyl)imino‐2, 5‐cyclohexadien‐1‐one
Authors: Fraterman H.A. , Romers C. 
Published: September 2010

AbstractCrystals of the title compound are monoclinic. The space group is P21//n, the lattice constants are a = 11.07, b = 11.38, c = 15.61 Å, β = 98.9° and Z = 4.The structure was solved by the conventional heavy‐atom technique based upon photographic X‐ray data. Intramolecular bond distances and valency angles are listed and appear to be quite regular. The dihedral angle between the phenyl and the cyclohexadiene ring amounts to 56°. The latter ring is slightly distorted towards the boat form. The tert‐butyl groups exhibiting a pronounced thermal libration about their bonds to the cyclohexadiene ring, are not disordered.
Chemistry of α‐diazosulfones, XII: α‐Alkoxy‐α‐chloro‐sulfones from tert‐butyl hypochlorite and α‐diazosulfones
Authors: Zwanenburg B. , Middelbos W. , Hemke G.J.K. , Strating J. 
Published: September 2010

AbstractThe reaction of α‐diazosulfones with tert‐butyl hypochlorite in tert‐butyl alcohol/dichloromethane gives α‐tert‐butoxy‐α‐chloro‐sulfones (II) in good yields. In dichloromethane as solvent the same compounds were obtained, while in ethanol/dichloromethane the corresponding α‐chloro‐α‐ethoxy‐sulfones were formed (Scheme 1, Table I). α‐Diazo‐carbonyl compounds and tert‐butyl hypochlorite give acetals in alcoholic solvents and α‐tert‐butoxy‐α‐chloro‐carbonyl compounds in dichloromethane (Scheme II, Table I). An ionic pathway for the reaction of these diazo compounds with t‐BuOCI is proposed. The initially formed ion pair RSO2CH(Cl)N2⊖. t‐BuO⊖ solvolyses or collapses with liberation of nitrogen.
Addition of chlorine to the cyanogen bond. III
Authors: Trompen W.P. , Geevers J. , Hackmann J. Th. 
Published: September 2010

AbstractThe addition of chlorine to some negatively substituted nitriles (cyanogen, trichloroacetonitrile and N.2,2‐trichlorocyanoacetimidoyl chloride) is described. The products have been identified as substituted N‐chloro‐formimidoyl chlorides.
CNitroso compounds. Part XVII: Conformational analysis of cycloalkyl nitroxides by ESR
Authors: Wajer Th. A. J. W. , Mackor A. , de Boer Th. J. 
Published: September 2010

AbstractESR spectra of dialkyl nitroxides with a cyclohexyl or l‐acetoxycyclohexyl group as one of the alkyl groups have been measured. The complex hyperfine structure of N‐t‐butyl‐N‐cyclohexyl nitroxide is interpreted with the aid of spectra of the γ‐ and δ‐deuterated analogues. The elucidation of the hyperfine structure of this radical facilitates the assignment of the hyperfine coupling constants (hfc′s) of other nitroxides. An explanation of the observed hfc′s in terms of radical conformations is given.
PMR cis/trans analysis of double bonds using alkyl substituent effects
Authors: Frost D. J. , Barzilay J. 
Published: September 2010

AbstractThe characterization of double bonds by the difference between the cis and trans shielding effects of alkyl groups upon the PMR chemical shifts of the ‐allylic protons is described. Application of the principle is demonstrated for 2‐unsaturated aldehydes, acetals, alcohols and ethers. Results at 220 MHz on three geometrical isomers of 5,8,11,14‐eicosatetraenoic acid show that it is even possible to characterize double bonds in polyunsaturated fatty acids.
A magnetic resonance study of methylene substituted aromatic hydrocarbon anions
Authors: van der Kooij J. , Gooijer C. , Velthorst N. H. , Maclean C. 
Published: September 2010

AbstractThe ESR spectra of the radical anions of 9. 10‐dihydrophenanthrene. 4.5‐ dihydropyrene. 9.1 0‐dihydroanthracene and 5.12‐dihydrotetracene have been measured and interpreted. Additional information on the hyperfine splitting constants has been obtained from a NMR study of the electron transfer reaction between the paramagnetic anions and the diamagnetic parent molecules.A kinetic process due to inversion of the molecular conformation in 9.10‐ dihydrophenanthrene has been studied quantitatively.