bluuebunny/crossref_metadata_2025 huggingface dataset:
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

Infrared 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

The 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

Twenty‐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.
Vibrational spectra of some indium compounds. Part II
Authors: Brinkmann F.J. , Gerding H.
Published: September 2010

Spectroscopic results are communicated for the solids In4Cl7, In2Cl3, InCl3 (C4H9)4NCl and InCl3 · 2[C4H9)4NCl].
Phase transitions in copper chalcogenides: I. The copper‐selenium system
Authors: Stevels A.L.N. , Jellinek F.
Published: September 2010

The 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

α‐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

Interaction 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

Crystals 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

The 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

The 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

ESR 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

The 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

The 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.
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

The 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

Photolysis 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

The 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

A 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

The 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

It 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

Evidence 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

The 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

Differences 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

The 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

A 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

Reaction 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

3,4‐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

2,5‐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

Dipotassium 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

Infrared 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

The 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

UV 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

A 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

The 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

The 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

The 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

Complex‐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

Crystals 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

Reaction 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

2‐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

The 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

Enamines 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

From 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

The 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

Treatment 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.
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

The 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

A 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

A 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

Phenanthroquinone 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

The 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

Tetrabromophosphonium 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

The 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

Two 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

(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

Ethylzinc 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

On 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

The 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

Certain 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 formation

According 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

The 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

“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

ESR 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

By 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

The 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

Prolonged 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.