bluuebunny/crossref_metadata_2025 huggingface dataset:
Anion polarization and lattice energy of some metal halides MX2 and MX3 with layer and chain structure
Authors: Arlman E. J.
Published: September 2010

The contribution of anion polarization to the lattice energy of inorganic compounds with layer‐ and chain‐lattice structure is calculated using an extension of the simple ionic model. This consists of assigning to the anions ideal dipoles, the direction of which is deduced from the structure. With the aid of a theorem due to de Wette the polarization energy per anion is expressed in terms of the form

containing the polarizability and diameter of the anion and two geometric constants representative of the ionic and the dipole field at the anion site. I and D depend on the crystal structure in an analogous way to the Madelung constant. By combination of polarization energy, Coulomb energy and Born repulsion energy, formulae for the lattice energy are obtained. They allow a quantitative representation of some trends in crystal chemistry and a rather close approximation to the thermodynamic lattice energy of real compounds.
NMR Spectra of some secondary substituted adamantanes. Part II: 2,4‐Dihalo‐substituted adamantanes
Authors: van Deursen F. W. , Udding A. C.
Published: September 2010

The NMR spectra of 2e,4e‐ and 2a,4e‐dihalo‐substituted adamantanes are analysed with the INDOR technique and the configurations are evaluated.

The observed chemical shifts are in agreement with the calculated ones using the substituent shifts from the 2‐monosubstituted adamantanes. Only a remarkable deviation exists for the protons geminal to the substituents, which is very deceptive for the evaluation of the configurations of 2,4‐disubstituted adamantanes.
Investigation into the conformation of a series of 2‐alkyl‐1‐(o‐alkylphenyl)cyclohexanols. Part 3: Synthesis and conformation of some trans‐1‐(o‐alkylphenyl)decahydro‐1‐naphthols
Authors: Timmerman H. , Th. Nauta W.
Published: September 2010

Several trans‐1‐(o‐alkylphenyl)decahydro‐1‐naphthols were synthesised from trans‐octahydro‐1(2H)‐naphthalenone with aryl‐lithium. Their conformations were assigned on the ground of the chemical shift of the hydroxyl proton. A comparison was made with the corresponding cyclohexanols.
The system zirconium‐selenium: Structures of the phases Zr3Se4 and Zr2Se3
Authors: Salomons W. , Wiegers G. A.
Published: September 2010

The system zirconium‐selenium has been investigated in the composition range ZrSe2ZrSe. In samples prepared from the elements at 800°C only the phases Zr1+xSe2 (with a Cd(OH)2 type structure) and Zr3Se4 were observed, in agreement with previous studies. The phase Zr3Se4 was found to have a rhombohedral structure intermediate between the CdCl2 and NaCl types; a 3.753 Å, c  18.703 Å. In samples prepared at 950° or 1200° a new hexagonal phase (a  3.744 Å, c  12.51 Å) of approximate composition Zr2Se3 was found; this phase was found to be isotypic with Ti2S3.
Substituent effects of pyrrolidino and piperidino groups in benzoic acids and nitrobenzenes
Authors: Weringa W. D. , Janssen Matthijs J.
Published: September 2010

Benzoic acids and nitrobenzenes, substituted in the para position with a pyrrolidino or a piperidino group are compared with dialkylaminobenzoic acids and dialkylaminonitrobenzenes.

The acidities of the substituted benzoic acids, the polarographic halfwave potentials of the nitrobenzenes and the rate of reduction of the nitrobenzenes with disodium disulfide, give the following order of electron releasing effect of the substituents:

piperidino < dimethylamino < pyrrolidino < diethylamino < di‐isopropylamino.

No steric inhibition or promotion of resonance is found with the pyrrolidino group, but steric inhibition of resonance seems important in the piperidinobenzenes. The basicities of the dialkylaminobenzoic acids show a greatly different sequence which is attributed to the changing configuration around the basic site.
Nuclear magnetic resonance studies of substituents in benzophenones, benzhydrols, and benzhydryl ethers
Authors: de Roos A. M.
Published: September 2010

The chemical shift of the substituent‐protons in a number of substituted benzophenones, benzhydrols, and benzhydryl ethers correlate well with the carbonoxygen absorption in the infrared spectra.
HF‐SbF5 catalysed isomerization of n‐butane‐1‐13C
Authors: Brouwer D. M.
Published: September 2010

n‐Butane‐1‐13C is isomerized by “HF‐SbF5” to n‐butane‐2‐13C without intermediate or concurrent isomerization to isobutane. The rate of the13C‐scrambling reaction is only slightly lower than that of the isomerization of n‐pentane to isopentane. This result strongly supports the hypothesis that alkylcarboniumion rearrangements that involve a change in the degree of chain branching proceed via a protonated cyclopropane ring. That no isobutane is formed can be explained by the ring opening of protonated methylcyclopropane to the isobutyl structure being “slow” because it involves the formation of an (incipient) primary ion. This is not contradictory to the fact that t‐butyl ions are formed in strong acids from n‐butyl precursors under different conditions. The difference between HF‐SbF5 catalysed and aluminium halide‐hydrogen halide catalysed isomerizations of butane is discussed.
Conformation of open‐chain compounds. Part 4. Carbon‐halogen stretching frequencies, dipole moments, and conformation of some 1‐halogeno‐1‐halogenomethylcyclohexanes and related compounds
Authors: Altona C. , Hageman H.J. , Havinga E.
Published: September 2010

Carbon‐halogen stretching frequencies of 1‐chloro‐l‐chloromethyl — (1), 1‐bromomethyl‐1‐chloro‐ (2), 1‐bromo‐1‐bromomethyl‐ (3), 1‐chloromethyl‐1‐hydroxy‐ (4), 1‐bromomethyl‐1‐hydroxy‐ (5) and 1‐bromomethyl‐1‐methoxycyclohexane (6) are reported. The frequencies were assigned to specific conformations by comparing the observed values with those predicted from the known “stretching parameters” of the several possible chemical/geometrical arrangements in the vicinity of the C‐Hal bond (P. T, S calssification).

The dipole moments of1, 3and5in carbon tetrachloride and benzene were measured to obtain quantitive information on the conformational properties of this class of compounds.

The dihalides exist as mixtures ofantiandgaucheconformations (tertiary halogen axial) with theantiform predominating on account of its lower energy content. A normal “benzene effect) is found.
The cause of the medium effect upon the rate of the electron‐exchange reaction between thallium(I) and thallium(III)
Authors: Gelsema W.J. , de Ligny C.L. , Blijleven H.A. , Hendriks E.J.
Published: September 2010

The thallium(I)‐thallium(III) electron‐exchange rate has been measured at 25° in aqueous perchloric acid‐lithium perchlorate mixtures of varying acid concentration, at three values of the ionic strength.

In these mixtures no detectable medium effect exists, i.e., the specific rate constant is independent of the acid concentration at each value of the ionic strength studied.

The medium effect that has been found in aqueous perchloric acid‐sodium perchlorate mixtures must therefore be explained as the result of a variation of the activity coefficients of the reacting species and not, as has been done by the majority of authors, as a result of displacement of hydrolysis equilibria.
Synthesis of some aliphatic dienals
Authors: Ward J. P. , van Dorp D. A.
Published: September 2010

4,7‐Decadienal, 4,7‐tridecadienal, 5,8‐tetradecadienal and 6,9‐dodecadienal (all‐cis) have been synthesized by coupling 1‐bromo‐2‐pentyne and 1‐bromo‐2‐octyne with the diethyl acetals of 4‐pentynal, 5‐hexynal and 6‐heptynal, followed by partial hydrogenation and hydrolysis. The formation of 1,1,4‐triethoxy‐2,5‐hexadiyne from 1,1‐diethoxy‐2‐propyne is also described.
A new method for handling volatile and hygroscopic substances in bomb calorimetry. Enthalpy of formation of liquid butanol‐1
Authors: Mosselman C. , Dekker H.
Published: September 2010

A new method has been developed for handling volatile and hygroscopic substances in bomb calorimetry. A platinum crucible, covered with a platinum lid and sealed with vaseline, is used. The lid is opened by a counterweight when the vaseline is ignited. The enthalpy of formation of liquid butanol‐1 was measured and compared with literature values.
The chemistry of cycloheptatriene. Part XVI . Sigmatropic shifts of hydrogen in methylcycloheptatriene
Authors: Ter Borg A. P. , Kloosterziel H.
Published: September 2010

Upon heating 7‐methylcycloheptatriene the 3‐, 1‐ and 2‐isomers are successively formed by 1‐5 shifts of hydrogen. The rate constants at 140° have been determined. Photochemical 1‐7 shifts of hydrogen are also reported: the 1‐isomer yields preferentially the 7‐isomer and little of the 2‐isomer, whilst the 2‐isomer yields mainly the 3‐isomer and little of the alternative 1‐isomer.
1,3‐oxathioles as intermediates in nucleophilic additions to 1‐acylthio‐1‐alkynes
Authors: Drenth W. , Nieuwdorp G. H. E.
Published: September 2010

In methanol, 1‐acetylthio‐1‐alkynes are converted into 1,3‐oxathioles

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In aqueous solution a similar intermediate is formed with a rate independent of the acidity and with a negligible solvent deuterium isotope effect. This intermediate rearranges to the end‐product at a rate that decreases with the acidity:

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Poisoning effects of hydrogen sulfide on noble metal electrodes. Part I. Rest potentials and stationary current density ‐ potential measurements on Pt and Au electrodes in H2SO4 solutions containing H2S
Authors: Ijzermans A. B.
Published: September 2010

The influence of H2S upon electrochemical reactions on Pt, platinized Pt, Au and Au/Pt electrodes in H2SO4 solutions has been investigated by means of rest potential measurements and stationary current vs. potential measurements under potentiostatic control.

In 0.5 M H2S04 saturated with H2S these electrodes reached a rest potential of 165 ± 10 mV (nhe), which was found to depend linearly on pH with ‐ 59 ± 2 mV/pH and on P with ‐40 ± 15 mV/log P.

Current density vs. potential curves showed an increase of hydrogen over‐potential under the influence of H2S and also a change of reactions at potentials > 0 mV. In this region the potential determining reaction may be an exchange of H+ ions with H atoms absorbed in the noble metal, proceeding along adsorbed HS− ions. Additional evidence supporting this view was obtained by studying the effect of scraping on rest potentials.
Polymer network characterization by means of swelling pressure and unilateral compression data
Authors: van de Kraats E. J. , Potters J. J. M. , Winkeler M. A. M. , Prins W.
Published: September 2010

The characterization of a polymer network entails at least the determination of three parameters, viz. the number of elastically effective chains v, the polymer diluent interaction parameter χ and the reference degree of swelling qo, at which the chains do not exert elastic forces on the crosslinks. In this study networks are described which are prepared by crosslinking poly‐(p‐nitrophenyl methacrylate) in solution with hexamethylene diamine. This yields gels of accurately known content of chemical crosslinks. Swelling pressure measurements (0–3 atm) coupled with unilateral compression data have been performed in order to determine the network parameters and to check the various forms of the theory of swollen rubber elastic networks. It is found that the functional relationships prescribed by the theory are indeed obeyed over a wide range of swelling from volume ratios of 5 to 20. The parameter v is constant over the whole range. If the number of chemically crosslinked chains is assumed to be equal to the number of elastically effective chains in the network, the data support the Flory‐Wall theory, although a modified form of the Hermans theory is also applicable. The reference degree of swelling qo is very large in these gels because they are formed by crosslinking in dimethylformamide in which the molecular chains are aggregated, while the swelling is measured in nitrobenzene in which the aggregates dissociate. This feature is also responsible for the interesting fact that it is the elastic free energy rather than the free energy of dilution which is negative and thus promotes the swelling of these gels.
The crystal structure of a monoclinic modification of 4‐cyano‐N‐[2‐(p‐methoxyphenyl)‐ethyl]pyridinium iodide, C15H18IN2O
Authors: Dik‐Edixhoven Lotty , Stam C. H.
Published: September 2010

The modification of 4‐cyano‐N‐[2‐(p‐methoxyphenyl)ethyl]pyridinium iodide investigated is monoclinic, space group Cc, Z = 4, cell dimensions a = 11.853, b = 12.485, c = 11.281 Å, β = 114.21°.

The conformation of the molecule is gauche about the central CC bond with a dihedral angle of 68°. The crystal structure does not explain the intramolecular charge transfer bands observed in the UV absorption spectrum.
Chemistry and spectroscopy in strongly acidic solutions. Part XXIII: Reversible reaction between carbonium ions and hydrogen
Authors: Hogeveen H. , Gaasbeek C.J. , Bickel A.F.
Published: September 2010

The reduction of aliphatic carbonium ions to alkanes with molecular hydrogen is reported. A kinetic study of this reaction has been made in the two‐phase solvent system HFFreon 113. The following parameters were investigated: temperature, hydrogen pressure, deuterium isotope effect and structure of the carbonium ion.

The kinetics of the reverse reaction ‐ formation of carbonium ions from alkanes and protons in the system HF‐SbF5 ‐ were studied for the case of trimethylcarbonium ion. From the equilibrium constant an upper limit for the basicity of isobutene has been calculated.
Studies on polypeptides. Part VII, : Synthesis of DL‐, L‐ and D‐2‐amino‐6‐dimethylamino‐4‐hexynoic acid
Authors: Jansen A. C. A. , Weustink R. J. M. , Kerling K. E. T. , Havinga E.
Published: September 2010

l‐ and D‐2‐amino‐6‐dimethylamino‐4‐hexynoic acid were synthesized, starting from L‐ and D‐propargylglycine obtained by enzymatic resolution of DL‐N‐ace‐tylpropargylglycine with acylase I. The dimethylaminomethylene group was introduced through a Mannich reaction of the N‐acetylpropargylglycine ethyl esters with formaldehyde and dimethylamine (Scheme A). By reaction of L‐ and D‐2‐amino‐6‐chloro‐4‐hexynoic acid, prepared by enzymatic resolution of the DL‐N‐acetyl compound, with dimethylamine identical end products were obtained, but in much lower yields (Scheme B).
Reaction between chlorodiphenylacetic acid and thiourea
Authors: Rahman Aziz Ur , Gatica Hector S. E.
Published: September 2010

The reaction between chlorodiphenylacetic acid and thiourea has been studied, using the former as such, as ethyl ester and the acid chloride, with or without the use of ethanol as solvent. The experimental conditions for the preparation of 5,5‐diphenylpseudothiohydantoin and the formation of 2‐(diphenylmethyl)imino‐4‐oxo‐5,5‐diphenylthiazolidine and/or bis(diphenyl‐methyl) disulfide as secondary products involving decarboxylation of chlorodiphenylacetic acid have been discussed.
Transannular interactions and reactions in a seven‐membered heterocyclic ring‐system
Authors: de Groot Ae. , Boerma J. A. , Wynberg Hans
Published: September 2010

Infrared spectroscopic studies have shown that transannular interactions occur in 4‐t‐butyl‐3,3,6,6‐tetramethyl‐1‐thiacycloheptan‐4‐ol (VI). These interactions do not occur in 3,3,6,6‐tetramethyl‐1‐thiacycloheptan‐4‐ol (III) and only to a minor extend in 3,3,4,6,6‐pentamethyl‐1‐thiacycloheptan‐4‐ol (IV) and in 3,3,6,6‐tetramethyl‐4‐isopropyl‐1‐thiacycloheptan‐4‐ol (V).

Treatment of 3,3,6,6‐tetramethyl‐1‐thiacycloheptane‐4,5‐diol (XVI) with acid gave a transannular rearrangement involving participation of the sulfur atom to 3,3,6,6‐tetramethyl‐1‐oxa‐4‐thiabicyclo[3.3.0]octane (XVII). Treatment of 5‐hydroxy‐3,3,6,6‐tetramethyl‐1‐thiacycloheptan‐4‐one with triphenyl‐phosphine dibromide gave a transannular rearrangement to 2‐isobutylidene‐4,4‐dimethyl‐3‐oxotetrahydrothiophene (XXVII).
Synthesis of 1,4‐, 1,5‐, 2,6‐ and 2,7‐di‐t‐butylnaphthalene and of 1,4‐, 1,5‐, 2,6‐ and 1,8‐diisopropylnaphthalene
Authors: van Bekkum H. , Nieuwstad Th. J. , van Barneveld J. , Klapwijk P. , Wepster B. M.
Published: September 2010

Mixtures of 2,6‐ and 2,7‐di‐t‐butylnaphthalene, obtained by the t‐butylation of naphthalene, can be conveniently separated making use of the fact that only the 2,6‐isomer gives an inclusion compound with thiourea.

1,4‐ and 1,5‐di‐t‐butylnaphthalene as well as 1,4‐ and 1,5‐diisopropylnaphthalene have been prepared starting from 1,4‐ and 1,5‐naphthalene‐dicarboxylic acid, respectively. The NMR spectra of these compounds reveal downfield shifts for the peri protons.

1,8‐Diisopropylnaphthalene was synthesized by an eight step synthesis starting from 1,8‐naphthalenedicarboxylic anhydride.
Diacetamide as a chelating anion
Authors: Hinze A. G. , Groeneveld W. L.
Published: September 2010

The preparation of diacetamide as chelating anion (DA) with the cations Na, Mg, Zn, Ni and Al is reported. The infrared spectra of Na(DA), Mg(DA)2·2NH3, Zn(DA)2, Ni(DA)2·2NH3 and A1(DA)3 are discussed. There is strong evidence for coordination occurring through oxygen.
The compound AsCl5·SbCl5 and the non‐existence of AsCl5
Authors: Brinkmann F. J. , Gerding H. , Olie K.
Published: September 2010

We have tried to prepare AsCl5 at low temperature by interaction of AsCl3 and Cl2 in a sealed tube. The Raman spectrum of the solid is a superposition of the vibrational spectra of AsCl3 and Cl2.

Also the compound AsCl5 · SbCl5 has been studied and from its Raman spectrum the structure is AsCl4+SbCl6−.
NMR spectra and configuration of some methylallylic anions
Authors: Heiszwolf G. J. , van Drunen J. A. A. , Kloosterziel H.
Published: September 2010

The NMR spectra of trans‐ (A) and cis‐3‐methyl‐trans‐l‐phenylallyl anion (B), of cis‐l‐methylpentadienyl anion and of cis‐l‐methyl‐5‐oxapentadienyl anion are described. A is obtained by abstraction of a proton from l‐phenyl‐trans‐2‐butene at low temperature. At 0° it largely isomerizes to B. Several aspects of the configuration of these anions are discussed.
Substituent effects in the dehydration of 2‐aryl‐3‐methyl‐2‐butanols and in the subsequent isomerization of 2‐aryl‐3‐methyl‐1‐butenes in sulfuric acid‐acetic acid and in dimethyl sulfoxide
Authors: Kieboom A. P. G. , van Bekkum H.
Published: September 2010

The dehydration of a series of 2‐aryl‐3‐methyl‐2‐butanols and the subsequent isomerization of the 2‐aryl‐3‐methyl‐l‐butenes primarily formed to the corresponding 2‐butenes have been studied in sulfuric acid‐acetic acid and in dimethyl sulfoxide.

The selective formation of the 2‐aryl‐3‐methyl‐l‐butenes during the dehydration is explained in terms of steric repulsion in the transition state.

For the isomerization of 2‐aryl‐3‐methyl‐l‐butenes Hammett rho values of ‐ 3.8 and ‐ 2.0 apply in sulfuric acid‐acetic acid and in dimethyl sulfoxide, respectively. The kinetic isotope effects support a mechanism in which the rate determining step is the loss of the methine proton to give the 2‐aryl‐3‐methyl‐2‐butene.
Pyrazoles and imidazoles as ligands: Part I. Some simple metal(II) perchlorates and tetrafluoroborates solvated by neutral pyrazole and imidazole
Authors: Reedijk J.
Published: September 2010

A number of new solvates containing pyrazole (Pz) and imidazole (Iz) as ligands, of the general formula M(ligand)n(anion)2 is reported. In these compounds M = Mg, Mn, Fe, Co, Ni, Cu, Zn and Cd, the anions are ClO4− and BF44−, and n is usually 6; n = 4 in the case of the Cu compounds and for Zn in combination with Iz.

The compounds are characterized and identified by chemical analysis and physical measurements.

With the aid of ligand‐field spectra in combination with X‐ray powder patterns, octahedrally coordinated metal ions are found in compounds of stoichiometry M(ligand)6(anion)2. Both Pz and Iz are placed in the spectro‐chemical and nephelauxetic series. The spectrochemical series appears to be (with increasing Dq): CH3CN < Iz < NH3 < Pz < en, whereas the nephelauxetic series (with decreasing B) has the sequence: CH3CN > NH3 > Iz > Pz > en.

The magnetic moments for the transition‐metal compounds fall within the range usually observed for octahedrally coordinated ions. Both paramagnetic resonance measurements and the deviation of the magnetic moments from the spin‐only value, indicate a considerable amount of covalency in the metal‐ligand bond.

Infrared spectroscopy evidently shows pure ionic ClO4− and BF4− for all solvates, except those of Cu(II) where the anions are coordinated to the metal ion. Except for the N‐H modes, no large shifts occur in the ligand infrared absorptions with respect to the free ligand. Compared with the gaseous ligands, the N‐H stretch in the solvates is decreased, whereas the bending modes are increased in frequency. This is attributed to ‐ weak ‐ hydrogen bonding with the anions in the lattice of these solvates.

Metal‐ligand stretching frequencies for both ligands occur in the 165‐330 cm−1 range, and follow the Irving‐Williams sequence of metal ions.
1‐Methylheptatrienyl and methylcycloheptadienyl anions
Authors: Kloosterziel H. , van Drunen J. A. A.
Published: September 2010

NMR spectroscopy has revealed that the reaction between trans,trans,trans‐ 2,4,6‐octatriene and potassium amide at ‐ 60° to ‐ 40° yields the trans‐ 1‐methyl, all‐trans heptatrienyl anion. At 0° this anion isomerizes largely to the cis‐1‐methyl anion. At room temperature the mixture of these two anions electrocyclizes completely to a mixture of 2‐ and 6‐methylcycloheptadieny! anions. The latter two anions are obtained separately from 3‐methylcyclohepta‐1,4‐diene and 5‐methylcyclohepta‐1,3‐diene, respectively.
A NMR study of N,N,N′,N′‐tetra‐alkylthiuram disulfides and their complexes with Zn, Cd and Hg
Authors: Brinkhoff H. C. , Grotens A. M. , Steggerda J. J.
Published: September 2010

Hindered rotation around the S2CNR2 bond of N,N,N′,N′‐tetra‐alkylthiuram disulfides is observed by NMR. The assumption that oxidation of bis‐dithiocarbamato complexes of Zn, Cd and Hg yield thiuram disulfide complexes of these metals is confirmed by the NMR spectra which reveal a magnetic non‐equivalence of the N‐alkyl groups. It is proposed that the metals in these complexes are tetrahedrally surrounded by two halogen and two sulfur atoms.
Synthesis of adamantane‐2‐carboxylic acid and of (2‐adamantyl)acetic acid from adamantanone
Authors: Scharp J. , Wynberg Hans , Strating J.
Published: September 2010

A convenient synthesis of adamantane‐2‐carboxylic acid and (2‐adamantyl)‐acetic acid starting with adamantanone is described.
A general method for the preparation of cumulenic ethers and thioethers
Authors: Mantione R. , Alves A. , Montijn P. P. , Wildschut G. A. , Bos H. J. T. , Brandsma L.
Published: September 2010

Solutions of lithiated cumulenic ethers and bis‐ethers R2CHCCC(Li)OR3 and R1OCHCCC(Li)OR3 can be obtained by treatment of the compounds R1OCH(R)2)CCCH2OR3 and R1OCH2CCCH(OR3)2 respectively with 2 equivalents of butyllithium in ether. Reaction of these solutions with H2O, D2O, methyl iodide, α‐chloro‐ethers or ketones gives the cumulenic compounds or their derivatives in good yields.

Solutions of lithiated cumulenic thioethers R2CHCCC(Li)SR3 are obtained in an analogous way, but hydrolysis affords the isomeric enynic thioethers R2CHCHCCSR3 in addition to the expected cumulenic thioethers R2CHCCCHSR3. Elimination of R1OH from R1OC(R2)2CCCH(SR3)2 with 1 equivalent of C4H9Li leads to the cumulenic dithioacetals (R2)2CCCC(SR3)2.
Sterols in vernonia anthelmintica seed
Authors: Frost D. J. , Ward J. P.
Published: September 2010

The main sterol of Vernonia anthelmintica seed is 7,(Z)‐24(28)‐stigmastadienol (Ia). Stigmasterol and a C29‐sterol with a conjugated diene system, probably at C8 and C14, are also present, whilst GLC data indicate two other components to be 5‐stigmasten‐3β‐ol and 7,22‐stigmastadienol. A correlation of NMR data is given showing the stereochemistry at the ethylidene group of Ia and in related compounds.
The structure of Willstätter's compound: 3‐benzoyloxy‐2‐methoxycarbonyl‐2‐tropene
Authors: Beyerman H. C. , Maat L. , Sinnema A.
Published: September 2010

Willstätter et al. obtained an unknown crystalline product by the benzoylation of 2‐methoxycarbonyl‐3‐tropanone. Proton magnetic resonance and infrared spectrometry have shown this product to be 3‐benzoyloxy‐2‐methoxycarbonyl‐2‐tropene, III. Attempted hydrogenation of III to a cocaine failed.
Studies on vitamin D and related compounds. Part 21. Photosensitized reactions
Authors: Snoeren A. E. C. , Daha M. R. , Lugtenburg J. , Havinga E.
Published: September 2010

The cis‐trans isomerisation of tachysterol3 and previtamin D3 trimethylsilyl ethers has been brought about by triplet sensitization. The two overall quantum yields have been estimated. It was found that the photochemical electrocyclic reactions of previtamin D3 yielding 7‐dehydrocholesterol and lumisterol3 go via singlet states. The irradiation mixtures were analysed by means of GLC.
Complexes with ligands containing the carbonyl group. Part II.: Metal(II) methyl formate, ethyl acetate and diethyl malonate solvates
Authors: Driessen W. L. , Groeneveld W. L. , van der Wey F. W.
Published: September 2010

Twenty‐six new coordination compounds are reported with methyl formate, ethyl acetate and diethyl malonate as the ligands, viz. [M(HCOOCH3)62+] [FeCl4−]2, [M(HCOOCH3)62+] [InCl4−]2, [M(CH3COOC2H5)62+] [SbCl6−]2, and [M(CH2(COOC2H5)2)32+] [SbCl6−]2, where M is Mg(II), Mn(II), Fe(II), Co(II), Ni(II), and Zn(II), and for the ethyl acetate and diethyl malonate solvates M is also Ca(II).

In the complexes the carbonyl stretching vibration is shifted to lower frequencies with regard to this vibration in the free ligands. The magnitudes of these shifts are dependent on the metal ions. Frequency‐shifts of other ligand vibrations are also observed. When the shifts are dependent on the metal ions, the magnitudes of the shifts follow the Irving‐Williams sequence.

For the methyl formate and ethyl acetate solvates a metal‐dependent absorption band appears in the far infrared, which is attributed to the metal‐ligand stretching vibration. This band could not be located for the diethyl malonate solvates.

Investigation of ligand field spectra indicates the presence of octahedral species M(O)62+ in the solid compounds. Values for Dq and B for the Co(II) and Ni(II) compounds are reported, and the ligands are placed in the spectro‐chemical and nephelauxetic series.
The crystal and molecular structure of 2‐Acetyl‐5‐Bromothiophene
Authors: Streurman Hetty J. , Schenk H.
Published: September 2010

Crystals of 2‐acetyl‐5‐bromo‐thiophene are orthorhombic, space group Pbca, Z = 8, cell dimensions a = 7.334, b = 11.156, c = 17.906 Å.

The conformation of the thienyl ring with respect to the carbonyl group is single‐trans.
Chemistry and spectroscopy in strongly acidic solutions. Part XXXI: Rates of carbonylation of stabilized carbonium ions
Authors: Hogeveen H. , Gaasbeek C. J.
Published: September 2010

The rate constants of carbonylation of some unsaturated carbonium ions and cyclopropylcarbonium ions have been determined. The results indicate that bicyclic homoallylic ions, e.g. the 7‐norbornadienyl ion, are stabilized by non‐classical electron delocalization.

In the case of allylic ions the oxocarbonium ions initially formed cyclize to give cyclopentenone derivatives in high yield.
Transformations of 3,17‐Dioxo‐Δ4‐Androsten‐19‐al to estrane derivatives
Authors: Siegmann C. M. , de Winter M. S.
Published: September 2010

3,17‐Dioxo‐Δ4‐androsten‐19‐al (II) is a suitable starting material for the preparation of estrane derivatives.

Autoxidation gives the corresponding 10β‐hydroperoxide III, which can be converted to estrone (V) by reduction and aromatization.

Treatment with alkaline reagents under various conditions can produce 3‐oxo‐Δ4‐ (VI), 3‐oxo‐Δ5(10) ‐ (VII) and 2‐hydroxymethylene‐3‐oxo‐Δ5(10) ‐ estrene (VIII) derivatives.
Hydrogenation of cyclohexene on evaporated nickel films
Authors: Erkelens J. , Eikema E. Th. J.
Published: September 2010

The reaction kinetics of the catalytic vapour‐phase hydrogenation of cyclohexene on evaporated nickel films has been studied in a temperature range from − 20 to − 45° in a flow system. To this end, an apparatus has been constructed in which hydrogen and cyclohexene partial pressures, flow‐rate and reaction temperature could be varied independently.

In the range studied, the reaction has been found to be zero‐order with respect to the cyclohexene and roughly half‐order in regard to the hydrogen partial pressure, indicating that the formation of chemisorbed C6H11 groups is the slow step in the reaction. The measured rate was compared with that calculated from the absolute‐rate theory.
The vibrational spectra and the ionic structures of the compounds SCl4·SO3, SeCl4· SO3, TeCl4 · SO3 and (CH3)4N · SO3Cl
Authors: Gerding H. , Stufkens D. J. , Gijben H.
Published: September 2010

Preparation, properties and Raman spectra of the compounds SCl4 · SO3, SeCl4 · SO3, TeCl4 · SO3 and (CH3)4N · SO3Cl are described. These compounds are ionic in nature, possessing the positive ions N(CH3)4, +, SCl3, +, SeCl3, + and TeCl3+ besides the common anion SO3Cl−.

The frequencies of the SO3Cl− ion in these compounds are compared with our assignment1. The Raman spectra of TeCl4 · GaCl3 (TeCl3·+GaCl4−) and SCl4 are given also.
Conversion of 4,6‐disubstituted pyrimidines into 1,2,4‐Triazoles by action of Hydrazine
Authors: van der Plas H. C. , Jongejan H.
Published: September 2010

4,6‐Diethoxy‐, 4‐ethoxy‐6‐hydrazino‐, 4,6‐dichloro‐, 4,6‐di(methylthio)‐and 4,6‐dihydrazinopyrimidine react with aqueous hydrazine at 210° to give 3‐methyl‐1,2,4‐triazole. Evidence is presented that in this unprecedented ring contraction reaction the C(2)‐N(3 or 1)‐C(4 or 6)‐C(5) fragment of the pyrimidine ring is involved in the formation of this 1,2,4‐triazole.
The photolysis of Cyclopropanecarbaldehyde at 313 nm and 254 nm in the presence of CIS‐Butene
Authors: Overwater J. J. I. , Cerfontain H.
Published: September 2010

Cyclopropanecarbaldehyde has been photolyzed in the gas phase with light of 313 nm and 254 nm in the presence of cis‐2‐butene. With increasing total pressure the quantum yields of the gaseous products, carbon monoxide, ethene, propene and cyclopropane, decrease. The photolysis is accompanied by isomerization of cis‐2‐butene to trans‐2‐butene, due to the transfer of triplet energy from the aldehyde to the olefin. The quantum yield of the 2‐butene triplet, ØBT, increases with increasing concentration of added cis‐2‐butene. At a temperature of 50°, ØBT is about proportional to the concentration of cis‐2‐butene. At a temperature of 150°, however, ØBT very quickly reaches a constant value which is much lower for the photolysis with light of 313 nm (ØBT ∼ 0.05) than for that with light of 254 nm (ØBT ∼ 0.25).
The raman and infrared spectra of AsBr3 in the liquid and solid phase
Authors: Stufkens D. J.
Published: September 2010

The observed Raman and infrared spectra of AsBr3 in the solid and liquid states are assigned; for the solid state according to the space group D42 of the crystal.
Instability of complexes containing the dicyclopentadienylvanadium(iv) group
Authors: Siegert F. W. , H. J. De Liefde Meijer
Published: September 2010

The preparation of complexes of the type (π‐C5H5)2VR2 has been attempted by reaction of one mole of vanadocene dichloride with two moles of an organo‐metallic reagent RM (RM = C6H5Na and C6F5Li); these reactions result in the formation of complexes of the type (π‐C5H5)2VR. The reaction of vanadocene dichloride with 1,4‐dilithio‐1,2,3,4‐tetraphenylbutadiene results in the formation of a tarrish polymer, whereas the corresponding reaction starting from titanocene dichloride yields the green complex (π‐C5H5)2Ti[C4(C6H5)4]. The failure of the preparation of complexes of the type (π‐C5H5)2VR2 is ascribed to steric reasons.
On the origin of the byproducts in the autoxidation of cyclohexane to cyclohexanol and cyclohexanone
Authors: Duynstee E. F. J. , Hennekens J. L. J. P.
Published: September 2010

Tracer experiments involving autoxidation of dilute solutions of inactive cyclohexanol and inactive cyclohexanone in 14C‐labeled cyclohexane have shown that a number of byproducts such as butanol, pentanol, butyric acid, valeric acid, caproic acid, and ϵ‐hydroxycaproic acid are to a large part formed directly from cyclohexane and not via cyclohexanol and cyclohexanone. The label distribution in ϵ‐cyclohexyloxycaproic acid, hitherto unknown as a byproduct in the cyclohexane oxidation, clearly indicated that this acid is formed from the addition product of cyclohexyl hydroperoxide and cyclohexanone.
A comparison of the behaviour of (1‐adamantyl)‐ and (2‐adamantyl)‐carboxylic acids during Kolbe electrolysis
Authors: van Zorge J. A. , Strating J. , Wynberg Hans
Published: September 2010

The anodic oxidation of adamantane‐2‐carboxylic acid in alcoholic solution leads to the formation of a mixture of radical‐derived and carbonium ion‐derived products, whereas adamantane‐1‐carboxylic acid yields only the carbonium ion‐derived product. (2‐Adamantyl)acetic acid gives chiefly the radical‐derived product in contrast to (1‐adamantyl)acetic acid, which yields carbonium ion‐derived products. In the electrolysis of 3‐(1‐adamantyl)propionic acid the radical‐derived compound is the main product. A rationalization of these results is presented.
A conformational study on glycerol in a D2O solution by means of 220 Mc PMR data
Authors: van Koningsveld H.
Published: September 2010

The PMR spectral parameters of glycerol in a D2O solution are determined at different temperatures with a PMR apparatus operating at 220 Mc.

With these parameters—assuming no correlation between rotational positions of the terminal CH2OH groups‐graphs are drawn of the population of a particular conformation as a function of the Jtrans ( JT) and JGauche ( JG) coupling constants. If the condition Eα ≤ Eβ ≤ Eγ is imposed the calculations show that the proportion of molecules in the αα conformation is about 20%.

The result is verified from “trial” values for JT and JG taken from the literature. If Eα < Eβ, the calculated values for Eβ‐Eα and Eγ‐Eα are 375 ± 100 cal and 200 ± 50 cal, respectively.
Organophosphorus compounds. Part IX: Decomposition of ω‐dimethylaminoalkyl methylphosphonofluoridates and isomerization of 2‐dipropylaminoethyl methylphosphonofluoridothionate
Authors: Benschop H. P. , van den Berg G. R. , Kraay G. W.
Published: September 2010

The decomposition product of 2‐dimethylaminoethyl methylphosphonofluoridate (IV, n = 2) was identified as 1,1,4,4‐tetramethylpiperazinium bis‐(methylphosphonofluoridate) (VI). In hexadeuteriodimethyl sulfoxide (60°), the first‐order rate of decomposition of IV (n = 2) is ∼ 830 times greater than the rate of the analogous decomposition of 2‐dimethylaminoethyl isopropyl methylphosphonate (XV).

The hitherto unreported O‐2‐dimethylaminoethyl methylphosphonofluoridothioate (IX, R = Me) degrades on heating to 1,1,4,4‐tetramethylpiperazinium bis(methylphosphonofluoridothioate) (XIII, R = Me), whereas IX (R = n‐Pr) rearranges to S‐2‐di‐n‐propylaminoethyl methylphosphonofluoridothioate (XI, R = n‐Pr). Arguments are put forward that the decomposition reactions of IV (n = 2), XV and IX (R = Me), as well as the rearrangement of IX (R = n‐Pr) proceed via a 1,1‐dialkylaziridinium cation.

The decomposition of 3‐dimethylaminopropyl methylphosphonofluoridate (IV, n = 3) at 40° gives a polymeric salt [VIII, Y = OPO(Me)F].
Synthesis of 2‐(6′‐carboxyhexyl)‐4‐hydroxy‐3‐(3′‐hydroxyoctyl)‐1‐cyclopentanone (racemic dihydroprostaglandin E1)
Authors: Klok R. , Pabon H. J. J. , van Dorp D. A.
Published: September 2010

By the reaction of 3‐(3′‐acetoxyoctyl)‐2‐(6′‐carboxyhexyl)‐2‐cyclopenten‐1‐one, the acetoxy derivative of Prostaglandin E1 ‐ 237 (PGE1 ‐ 237), with N‐bromosuccinimide in carbon tetrachloride, followed by treatment of the reaction product with silver acetate in acetic acid, an acetoxy group was introduced at the allyl position of the ring. After hydrolysis of both acetoxy groups, 2‐(6′‐carboxyhexyl)‐4‐hydroxy‐3‐(3′‐hydroxyoctyl)‐2‐cyclopenten‐1‐one was obtained.

In an attempt to convert the latter into 2‐(6′‐carboxyhexyl)‐4‐hydroxy‐3‐(3′‐hydroxyoctyl)‐1‐cyclopentanone (racemic dihydro‐PGE1), hydrogenation with a 5 % rhodium on carbon catalyst was carried out. Both reduction of the double bond in the ring and hydrogenolysis of the hydroxy group attached to the ring occurred, leading to 2‐(6′‐carboxyhexyl)‐3‐(3′‐hydroxyoctyl)‐1‐cyclo‐pentanone. However, racemic dihydro‐PGE1 was also obtained in low yield. It showed some biological activity on blood‐platelet aggregation.
Photochemical cycloaddition of o‐quinones to allenes; 2‐alkylidene‐2,3‐dihydro‐1,4‐dioxins
Authors: Bos H. J. T. , Slagt C. , Boleij J. S. M.
Published: September 2010

Phenanthroquinone was added photochemically to allene and nine of its methyl, methoxy and methylthio derivatives. Several 2‐alkylidene‐2,3‐dihydrophenanthro[9,10‐b]‐1,4‐dioxins were isolated; 2: 1‐adducts were sometimes found as byproducts. The directiospecificity of the addition was investigated. The stereochemistry and conformation of the adducts are discussed in relation to long‐range NMR coupling constants. Tetrachloro‐o‐benzoquinone was added similarly to methoxyallene. This addition could also be performed thermally.
Hydrogen bonding. Part III: The proton acceptor ability of S = O groups: Sulfinic esters and sulfinyl chlorides as hydrogen bond acceptors
Authors: Engberts J. B. F. N. , Zuidema G.
Published: September 2010

Intermolecular hydrogen bonding between phenol and a series of sulfinic esters and sulfinyl chlorides has been studied by IR spectroscopy. The magnitudes of the OH stretching frequency shifts, Δν, indicate that inductive effects of substituents attached to the sulfur atom predominate over resonance effects in determining the sulfur‐oxygen bond polarity.

The Δν values of nine different types of sulfinyl, XS(O)Y, and sulfonyl, XSO2Y, compounds (X and/or Y are CH3, CH3O, Cl) are compared and interpreted in terms of the ground state electron availibility on the oxygen atom of the SO acceptor site. The preparation of the first representative of an aryl alkanesulfinate, CH3S(O)OC6H5, is described.
Rhodaninato‐ and 3‐substituted rhodanine complexes of palladium and platinum
Authors: Moers F. G. , Langhout J. P.
Published: September 2010

Palladium and platinum complexes of the rhodaninato ion and 3‐substituted rhodanines have been prepared. From infrared spectra in the 4000‐200 cm−1 region and nuclear magnetic resonance data it is concluded that for the compounds ML2X2 (where X = Cl, Br, I and L = 3‐substituted rhodanine) the metal is bonded via the thiocarbonyl group of the ligand. The assignment of the M‐X and M‐S stretching vibrations is given and discussed. In the compounds ML2 (where L is the rhodaninato ion) the rhodanine is complexed as monobasic anion. For these complexes we suggest a polymeric structure in which the coordination takes place through the nitrogen and the thiocarbonyl group of the ligand.
Raman and infrared spectroscopic investigations of the SbCl4− and AsCl4− ions
Authors: Stufkens D. J. , Wilmans A. M. , Gerding H.
Published: September 2010

The preparation, Raman and infrared spectra of (PyH)SbCl4, (Et4N)SbCl4, (Bu4N)SbCl4 and (Bu4N)AsCl4 are reported. The spectra of (PyH)SbCl4, (Et4N)SbCl4 and (Bu4N)AsCl4 demonstrate the polymeric behaviour of SbCl4− and AsCl4−; (Bu4N)SbCl4 on the other hand shows the spectrum of a monomeric ion SbCl4− in the solid phase and in dilute solutions.
A NMR and dielectric study of some adducts of aluminium halides and phosphines
Authors: Vriezen W. H. N. , Jellinek F.
Published: September 2010

The 27Al magnetic resonance was studied in benzene and toluene solutions containing AlX3 (X = Cl, Br) (0.2−0.25 M) and PR3 (R = C2H5, C6H5) in molar ratios varying from 1: 1 to 1: 16. In the solutions containing P(C6H5)3 the adducts (C6H5)3PAlX3 were found to be the only Al‐containing species present in significant concentrations. In solutions containing P(C2H5)3, adducts (C2H5)3PAlX3 and {(C2H5)3P}2AlX3 are present; the stability constants of {(C2H5)3P}2AlX3 were determined. These results are supported by dielectric measurements, which show the adducts {(C2H5)3P}2AlX3 to have small dipole moments, probably due to a trigonal‐bipyramidal structure with the phosphine ligands in the axial positions.
Thiophene analogues of fluorene and diphenylmethane‐autoxidation reactions
Authors: Rawson G. , Wynberg Hans
Published: September 2010

Oxidation of the isomeric cyclopentadithiophenes by oxygen in the presence of potassium t‐butoxide in t‐butanol‐dimethyl sulfoxide (4 : 1), or Triton B in pyridine, caused a cleavage reaction to occur and gave the corresponding bithienylcarboxylic acids. In contrast, the dithienylmethanes gave the corresponding dithienyl ketones. The Michael reaction of 7 H‐cyclopenta[1,2‐b: 4,3‐b′]dithiophene with acrylonitrile is also described.
Thiophene analogues of fluorenone: Cleavage reactions
Authors: Rawson G. , Wynberg Hans
Published: September 2010

The cleavage reactions of non‐enolizable thienyl ketones have been studied. Potassium t‐butoxide in t‐butanol, ether or dioxane has proved to be a mild cleavage reagent. With most ketones high yields of acids were obtained after a short reaction time at room‐temperature. Possible mechanisms for these mild reactions and the Haller‐Bauer cleavage of thienyl ketones are discussed.
Enthalpies of transfer of alkali halides between different solvents
Authors: Somsen G. , Weeda L.
Published: September 2010

Enthalpies of solution of alkali halides in formamide, N‐methylformamide, N, N‐dimethylformamide, N‐methylacetamide, dimethyl sulfoxide, water, methanol and ammonia are discussed. The ensuing enthalpies of transfer between any two solvents are nearly constant for salts with a common anion. The enthalpies of solution of a single salt in the different liquids can be correlated with the structure of the solvent.
Raman spectra of phosphorus pentabromide, phosphorus heptabromide and caesium tribromide
Authors: Gabes W. , Gerding H.
Published: September 2010

The Raman spectra of solid powders of phosphorus pentabromide, phosphorus heptabromide and caesium tribromide are reported. The spectra are explained in terms of site symmetry splitting and factor group splitting.
N,N‐dimethylaminoacetylene: (Short Communication)
Authors: Brandsma L.
Published: September 2010

N,NDimethylaminoacetylene. HC  CN(CH3)2 has been obtained in about 55% yield by elimination of thiol from the ketene‐N,S‐acetal H2CC (SC4H9)‐(N(CH3)2). The latter compound was synthesized by converting CH3C (O)N‐(CH3)2 into the corresponding thioamide (94% yield) and treating the anion of the thioamide (generated by means of potassium amide) with butyl bromide (85% yield).
Ultraviolet absorption spectra of some aromatic tricyclic ketones
Authors: Rekker R.F. , Nauta W. Th.
Published: September 2010

The UV absorption spectra of a small series of aromatic tricyclic ketones derived from benzophenone by introduction of an interconnecting ‐(CH2)n‐bridge (n = 1, 2, or 3) are described. The spectra show well‐defined steric effects in the 270‐nm region and they appear to be related to those of I‐indanone, I‐tetralone and similar structures with a corresponding band at about 240 nm. The band system is of conjugative origin and shows one single maximum ‐ with one exception: 10.11‐dihydro‐2,4‐dimethyl‐5H‐dibenzo[a.d]cyclohepten‐5‐one shows two separate maxima: at about 245 nm and 275 nm.
Phase transitions in copper chalcogenides II. The tellurides Cu3‐x Te2 and CuTe
Authors: Stevels A.L.N. , Wiegers G.A.
Published: September 2010

The thermal behaviour of the phases Cu3‐x Te2 and CuTe has been investigated by X‐ray diffraction at continuously varying temperature and by differential thermal analysis. Cu3‐x Te2 has an orthorhombic structure at room temperature which is closely related to the tetragonal structure of defective Cu2Sb type stable above 140°. Above 360° a face‐centred cubic form was found; the transition tetragonal ⇄ f.c.c. takes place via another (rhombohedral?) form. The atomic arrangements in the orthorhombic and f.c.c. forms have been studied. CuTe was found to disproportionate at 340° into Cu3‐x Te2 and a tellurium‐rich melt.
Synthesis and biological activity of four analogues of β‐corticotropin
Authors: Tesser G.I. , Buis J.T.
Published: September 2010

The syntheses of four ACTH‐analogues: [Orn15‐18]‐, [DSer1, Orn15‐18]‐, [Orn11‐15‐18]‐ and [DSer1, Orn11,15‐18]‐β‐corticotropin‐(1‐18)‐octadecapeptide amide** are described. The last mentioned compound exhibits an unexpected, strongly prolonged, biological activity. A possible explanation is given.
Conformation of non‐aromatic ring compounds part 69: An electron diffraction study of gaseous cyclopentanone
Authors: Geise H. J. , Mijlhoff F. C.
Published: September 2010

The gas‐phase molecular structure of cyclopentanone has been investigated. Bond lengths, valency angles and amplitudes of skeletal vibrations have been determined and were found to be normal. The puckering of the five‐membered ring, as given by Ømax = = 37.2 (or q = 0.38 Å), is less than in cyclopentane.
Hydrogenation and isomerization of unsaturated hydrocarbons catalysed by hydrogenated 1‐methylallyldicyclopentadienyltitanium(III)
Authors: Martin Hendrik A. , de Jongh R. O.
Published: September 2010

Hydrogenated 1‐methylallyldicyclopentadienyltitanium(III) in hydrocarbon solution is an active homogeneous catalyst for the hydrogenation of unsaturated hydrocarbons at room temperature. 1,3‐Dienes are not hydrogenated to completeness if they are capable of forming syn,syn‐1,3‐dialkyl‐substituted allyl complexes with the catalyst. 1‐Alkynes are not hydrogenated but polymerize rapidly to trans‐polyacetylenes. In the absence of hydrogen, 1,5‐cyclo‐octadiene is isomerized to the 1,3‐isomer via 1,4‐cyclo‐octadiene. Small amounts of hydrogen promote this double bond migration. 1‐Alkenes are converted selectively into 2‐alkenes at room temperature in a few minutes. Initially, the trans‐isomer is formed preferentially, followed by a slower trans‐cis isomerization.
An empirical investigation of the accuracy of virial equations for apolar and slightly polar vapours
Authors: Hammers W. E. , de Ligny C. L.
Published: September 2010

The applicability of the Berthelot, the Guggenheim‐McGlashan, the Pitzer‐Curl, the McGlashan‐Potter, and the Kreglewski virial equation to gas imperfection calculations has been examined empirically. For this purpose, calculated virial coefficients were compared with experimental data for a number of normal and branched alkanes, some polymethylenes, some aromatic and halogenated hydrocarbons, and ethers.
Synthesis of tri(aryloxy)methanes
Authors: Scheeren J. W. , van Roy M. J. H. M. , van der Veek A. P. M.
Published: September 2010

A convenient synthetic procedure is described for the preparation of triphenoxymethanes from aryl dichloromethyl ethers1and sodium phenolates in dimethoxyethane.
The oxidative conversion of toluene to benzene
Authors: de Jong J. G. , Batist Ph. A.
Published: September 2010

An oxidative reaction is described by which toluene is converted into benzene. The reaction is catalyzed by bismuth uranate. Selectivities up to 70% are obtained if toluene vapour reacts with the catalyst without gaseous oxygen being present; the catalyst becomes partially reduced, but can easily be reoxidized afterwards with air. Biphenyl and benzaldehyde have been identified as by‐products.
On the formation of allenes in the steroid series II. Synthesis and structure of several 19‐nor‐17,20‐pregnadienes
Authors: van Dijck L. A. , Lankwerden B. J. , Vermeer J. G. C. M. , Weber A. J. M.
Published: September 2010

A number of 19‐nor‐pregnane derivatives bearing a 17,20‐diene side‐chain has been synthesized; the stereochemistry of the products formed during the preparation of non‐substituted, mono‐ and dimethyl allenes has been studied by means of application of Brewster's Rules and NMR spectroscopy.