bluuebunny/crossref_metadata_2025 huggingface dataset:
Complexes with ligands containing nitrile groups: Part XII. Metal(II) and metal(I) acetonitrile solvates with tetrabromometallate(III) anions
Authors: Reedijk J. , Vervelde J. B. , Groeneveld W. L.
Published: September 2010

A number of solvates having the general formula M(CH3CN)m(M′Br4)n is reported. In this formula M = Cu(I), or one of the divalent ions Mg, Ca, Mn, Fe, Co, Ni, Cu, Zn, Cd; m is 4 or 6; M′ = Al, Fe, In, Tl; and n = 1 or 2.

The compounds are prepared by bromide‐ion transfer reactions between MBr2 (or CuBr) and M′Br3 in anhydrous acetonitrile.

Characterization and identification of these solvates were performed with the aid of chemical analyses, infrared spectra, ligand‐field spectra and X‐ray powder diagrams.

The M′Br4− anions are demonstrated to be tetrahedrally co‐ordinated, whereas the M(CH3CN)62+ cations are octahedrally co‐ordinated with nitrogen as the donor atom of CH3CN.
Dithieno‐1,4‐thiazines. Part I
Authors: Grol C. J. , Faber J. S.
Published: September 2010

The synthesis of the first dithieno[2,3‐b : 2′,3′‐e]‐1,4‐thiazine is described, this compound was prepared by condensation of 3‐thiophenethiol with methyl 2‐bromo‐3‐nitrothiophene‐5‐carboxylate followed by reduction, acylation, bromination with NBS and ringclosure with Cu, K2CO3 in nitrobenzene.

A thieno‐1,4‐benzothiazine was prepared in the same way. These compounds were synthesized in order to study the suggested correlation between charge‐transfer complexes vs. physiological activity.
C‐nitroso compounds. Part XIV: Oximes, nitroalkanes and alkyl nitrates by photolysis of C‐nitroso compounds and alkyl nitrites
Authors: Mackor A. , de Boer Th. J.
Published: September 2010

Monomeric primary and secondary nitrosoalkanes have been generated from the trans‐dimers by heating in solution. The monomers are photochemically and thermally far more reactive than the dimers. They are isomerized to oximes in 90% yield thermally. Photolysis of nitrosocyclohexane with red light leads to the oxime in 60% yield. Photolysis in the presence of oxygen gives nitrocyclohexane as the main product (85%), together with a small amount of cyclohexyl nitrate.

Considerable amounts of cyclohexanol are formed by oxidation of the solvent cyclohexane, presumably via a nitroxide‐type intermediate.

When t‐butyl nitrite is photolyzed with light in the region of 400 nm and in the presence of oxygen in CFCl3, t‐butyl nitrate is produced in 90% yield, by the action of intermediary NO and NO2 radicals.
Chemistry and spectroscopy in strongly acidic solutions. Part XXX: Study of the carbonylation of carbonium ions by NMR spectroscopic measurements
Authors: Hogeveen H. , Baardman F. , Roobeek C. F.
Published: September 2010

The rate constants of the equilibrium R⊕ + CO ⇄ RCO⊕ have been determined by NMR spectroscopic measurements for R = t‐butyl. The rates and the activation parameters of the decarbonylation reaction are equal in HF/SbF5 (1: 1 molar ratio) and FHSO3/SbF5 (1: 1 molar ratio), while the second‐order rate constant of carbonylation is about a factor of 10 smaller in the former solvent system than in the latter.

The equilibrium constant K = [RCO⊕ / [R⊕] [CO] was found to be only 15‐30 times as large for R = 2‐exo‐norbornyl and 1‐adamantyl as for R = t‐butyl and t‐pentyl. This is an indication of the unusually high stabilization of the norbornyl ion. The rates of the reactions of the carbonylation equilibrium are low for R = 2‐exo‐norbornyl, compared with those for R = t‐butyl, t‐pentyl and 1‐adamantyl, which is attributed to steric factors.
Conformation of non‐aromatic ring compounds. Part 61 Conformational equilibrium in trans‐2‐halogenocyclohexanols
Authors: Buys H. R. , de Vries H. J. A. , Hageman H. J. , Altona C.
Published: September 2010

The conformational equilibrium in trans‐2‐bromo‐ and trans‐2‐chloro‐cyclohexanol has been studied with the aid of dipole moments, NMR, IR and Raman spectroscopy. The physical properties of the individual conformers are obtained from the suitably biased 4‐ or 5‐t‐butyl derivatives. The diequatorial form appears to predominate strongly in solution. A comparison is made with the conformational features of the trans‐1,2‐dihalogenocyclohexanes.
The determination of the redundancy relations among the bending coordinates around a central atom
Authors: Ypenburg J. W.
Published: September 2010

The redundancy relations among the bending coordinates around a central atom have been derived to second order approximation by means of spherical trigonometry. The formalism derived here is not always applicable. A numerical result is more easily obtained by means of the formalism given here than in the generally applicable methods proposed by Crawford1 and Cihla and Pliva2.
Stereospecific reaction of isopropyl methylphosphonofluoridate (sarin) with α‐cyclodextrin: A model for enzyme inhibition
Authors: van Hooidonk C. , Breebaart‐Hansen J. C. A. E.
Published: September 2010

The rates of alkaline hydrolysis of the enantiomers of isopropyl methylphosphonofluoridate (Sarin) have been determined without and with varying concentrations of α‐cyclodextrin (cyclohexaamylose) in aqueous 0.1M/‐KCl solution at pH 9.0 and 25°.

The pseudo first‐order rate constants are reported. The observed kinetics and product analysis are consistent with a reaction scheme in which complex formation precedes the nucleophilic reaction of α‐cyclodextrin with Sarin. Dissociation constants (Kdiss) of the inclusion complexes and rate constants (k2) for the nucleophilic reaction are reported. The results indicate a stereospecific formation of the inclusion complexes, (S)‐(+)‐Sarin forming a more stable complex than (R)‐(‐)‐Sarin, as well as a stereospecific rate of reaction, (R)‐{‐)‐Sarin reacting faster than (S)‐(+)‐Sarin. The α‐cyclodextrin‐Sarin system represents the first model reaction for enzyme inhibition showing typical properties as complex formation, saturation effects and stereospecificity.
Rearrangements of 1,2,3,4,5‐, 1,2,4,4,5‐, 1,3,4,4,5‐ and 1,2,3,4,4‐pentamethylcyclopentenyl ions and of 1,3,4,4,5,5‐ and 1,2,3,4,4,5‐hexamethylcyclopentenyl ions. stability of pentamethylcyclopentenyl ions
Authors: Brouwer D. M. , van Doorn J. A.
Published: September 2010

A detailed investigation has been made of the reversible rearrangement of the 1,2,3,4,5‐pentamethylcyclopentenyl ion (1) to the 1,2,3,4,4‐pentamethylcyclopentenyl ion (3). In 5: 1 FSO3H‐SbF5 this reaction proceeds entirely intramolecularly by 1,2‐hydrogen and methyl shifts via three allylic and four non‐conjugated tertiary pentamethylcyclopentenyl ions as intermediates. Two of the intermediate allylic ions have been prepared by cyclization of the 2,4,6‐trimethylheptadienyl ion and their rearrangements have been further investigated.

Rate constants of the various rearrangements are reported and a detailed free‐energy profile of these reactions is presented.

The 1,3,4,4,5‐pentamethylcyclopentenyl ion (4) is 4.7, and the 1,2,4,4,5‐isomer (5) 10.0 kcal · mole−1 less stable (in terms of ΔF at 50°) than 1; these large differences are partly ascribed to the crowding of the three methyl groups on C4 and C5 in the former two ions.

The cation 1 occurs as cis and trans isomers, which are formed in a 1: 1 ratio upon protonation of the diene, and in a 2.3: 1 ratio upon rearrangement of 5 and 4. Their equilibrium ratio is 0.37: 1, which may indicate a non‐planar structure for this ion.

Our re‐examination of the cyclization of the 2,4,6‐trimethylheptadienyl ion in FSO3H‐SbF5 gave results considerably different from those reported by previous workers.

In the 1,2,3,4,4,5‐hexamethylcyclopentenyl ion (2) degenerate equilibrations through alternating hydrogen and methyl shifts cause line broadening in the PMR spectrum above 120°. These shifts are faster than the corresponding shifts of hydrogen in 1 and of methyl in 3, respectively, which is attributed to a steric acceleration due to the crowding of the three methyl groups on C4 and C5 in 2. Similar steric effects are held responsible for the fact that the rearrangement of 1,3,4,4,5,5‐hexamethylcyclopentenyl ion to 2 is much faster than that of 4 to 1 and 3, and that in 5 the methyl shift is almost as fast as the hydrogen shift.
1,3‐Oxathioles as intermediates in nucleophilic additions to 1‐Acylthio‐1‐Alkynes. II
Authors: Drenth W. , de Gruijter H. J.
Published: September 2010

In aqueous solution, 1,3‐oxathioles (IV; R″ = alkyl), are rapidly hydrolysed to II and subsequently converted into 1‐acylthio‐2‐alkanones (III) at a rate proportional to [OH⊖]. The solvent deuterium isotope effect of the latter conversion amounts to 1.82 ± 0.05. These data support a mechanism involving rapid deprotonation, followed by rate‐determining ring opening.
Alkyl‐ and Aryl‐Thiolation.: A kinetic study with bis‐phenylsulfonylmethane
Authors: Bosscher J. K. , Kloosterziel H.
Published: September 2010

The kinetics of the reaction of bis‐phenylsulfonylmethane with thiosulfonic esters (RSSO2R′) have been measured in 100% ethanol, in the presence of triethylamine, at 20°. The kinetic data on the substitution of an ‘active’ hydrogen by a thioaryl or thioalkyl (RS) group are compatible with a two‐step mechanism. First the carbanion of bis‐phenylsulfonylmethane is formed by action of the base after which a bimolecular reaction occurs between the carbanion and the thiosulfonate. The reaction is retarded by introduction of electrondonating substituents in both R and R′. The possible structure of the transition state is discussed.
The assignment of the vibrational frequencies of the SO3Cl− Ion
Authors: Stufkens D. J. , Gerding H.
Published: September 2010

The Raman spectra of HSO3Cl in CH3COOH and NaSO3Cl in N,N‐dimethylacetamide are recorded. From these spectra the SO3Cl− frequencies are reassigned. The new assignment is in agreement with the Raman spectra of solid (CH3)4N · SO3Cl, SCl4 · SO3, SeCl4 · SO3 and TeCl4 · SO3.
An NMR Study of intramolecular shielding in Alkyl N(Arylsulfonyl)Methyl]‐Carbamates, ‐Thiolcarbamates, ‐Thionocarbamates, and ‐Dithiocarbamates
Authors: van der Werf S. , Engberts J. B. F. N.
Published: September 2010

The chemical shifts of the ester alkyl groups of alkyl N‐[(arylsulfonyl)methyl]‐carbamates are displayed as doublets of unequal intensity at temperatures where rotation around the nitrogen to carbonyl bond is slow on the NMR time scale.

Comparison with NMR data of simple alkyl N‐substituted carbamates indicates that the ester alkyl absorption of at least one of the rotamers shows an appreciable upfield shift. These upfield shifts are dependent on the ring current in the aromatic nucleus of the molecule. An explanation for these observations is presented in terms of preferred conformations (with minimized lone pair‐lone pair repulsion) in which the ester alkyl group is situated above (or below) the plane of the aromatic ring. Minor structural changes in the molecule eliminate the shielding effect which supports the proposed shielding mechanism. Further evidence for intramolecular shielding was obtained from the observed solvent and temperature dependence of the chemical shifts of the ester alkyl protons. No evidence could be obtained for inter‐ or intramolecular association between the aromatic ring and the ester function.

Chemical shift data for alkyl N‐[(arylsulfonyl)methyl]thiolcarbamates, ‐thionocarbamates and ‐dithiocarbamates also indicate intramolecular shielding of the ester alkyl protons.
Homogeneous hydrogenation of substituted cinnamic acids with pentacyanocobaltate(II)
Authors: Basters J. , van Bekkum H. , van Reijen L. L.
Published: September 2010

The homogeneous hydrogenation of a series of substituted trans‐cinnamic acids with pentacyanocobaltate(II)‐ion has been investigated. The reactions were found to be first order in pentacyanohydridocobaltate(III) as well as in substrate, and zero order in cyanide. Electronic substituent effects may be expressed in terms of a Hammett‐Yukawa relationship with ρ = 0.67. In the hydrogenation of cis‐cinnamic acid partial isomerization to the trans‐isomer was observed. The deuteration of cis‐ and trans‐cinnamic acid and the hydrogenation of α,β‐dideutero‐cis‐cinnamic acid have been studied. The results can be understood by considering the reaction as a stepwise hydrogen atom transfer from the hydride to the substrate.
Mass spectra of α,β‐substituted butenolides
Authors: Reinhoudt D. N. , van de Graaf B.
Published: September 2010

The mass spectra of twenty‐six β‐ and α,β‐substituted butenolides have been examined. Fragmentation of the butenolide ring can be rationalised on the basis of the fragmentation pathways described for β‐hydroxybutenolides. However, a number of butenolides, e.g. the α‐(substituted)benzamido‐β‐hydroxymethyl‐butenolides, show a weak fragmentation of the ring. The fragmentations in which the substituents are involved are more favourable and interactions between the substituents on the α‐ and β‐positions complicate these spectra.
The reaction of acetals with bromine in sulfur dioxide
Authors: Dusseau Ch. H. V. , Schaafsma S. E. , de Boer Th. J.
Published: September 2010

The reaction of bromine with a variety of dimethyl acetals at − 60° in sulfur dioxide is described. Electrophilic attack of bromine on oxygen leads to methyl hypobromite (CH3OBr) together with mono methoxycarbenium bromide or ‐ depending on the stability of the cation ‐ its covalent counterpart, the α‐bromo‐ether. The reaction is catalysed by acids. Acetals derived from linear and cyclic carbonyl compounds react in this way with one exception: with 1,1‐dimethoxycyclopropane, the acetal of cyclopropanone, electrophilic attack by bromine is not on oxygen, but on the cyclopropane ring. Ring rupture leads to a relatively stable di methoxycarbenium ion.
Complex formation between organic nitro compounds and sulfur trioxide
Authors: Cerfontain Hans , Koeberg‐Telder A.
Published: September 2010

NMR evidence is presented for complex formation between nitromethane and sulfur trioxide in thrichlorofluoromethane as solvent according to . In addition, kinetic evidence for complex formation between nitrobenzene and sulfur trioxide in trichlorofluoromethane was obtained from sulfonation studies of that system.
Pyrazoles and Imidazoles as ligands. Part III: Coordination compounds containing 3(5)‐methylpyrazole and metal(II) salts
Authors: Reedijk J.
Published: September 2010

A number of compounds with general formula M2+(MPZ)n(anion)2 is reported, in which M = Mn, Fe, Co, Ni, Cu, Zn and Cd; MPZ = 3(5)‐methylpyrazole, n = 2–7, and the anions are ClO4, −, BF4, −, NO3, −, CNS−, Cl−, Br−, I−.

The compounds are characterized by chemical analyses, X‐ray powder diagrams, ligand‐field spectra, paramagnetic susceptibility and resonance measurements, and vibrational spectra.

The ligand MPZ is found to coordinate via the imino lone pair electrons, with the methyl group most probably located in the 5‐position, trans to the coordinated metal ion.

With respect to the same anion, groups of isomorphous compounds were found according to the X‐ray powder patterns. Ligand‐field spectra of the coloured transition‐metal ion complexes indicate that MPZ is a stronger coordinating ligand than the unsubstituted pyrazole. This is confirmed by the magnetic susceptibility measurements and the paramagnetic resonance spectra.

Fairly regular octahedral groups M(MPZ)6 2+ are found for the compounds with perchlorate and tetrafluoroborate anions (except for Cu2+), whereas strongly distorted tetragonal groups M(MPZ)4(anion)2 are found for the compounds containing the other anions (and for the Cu2+ compounds with BF4 − and ClO4 − anions). Infrared spectra of these latter compounds confirm the coordination of the ClO4, −, BF4− and NO3− anions, since split anion absorptions are found.
Synthesis of some 3‐deoxy‐heptulosonic acids
Authors: Paerels G. B. , Geluk H. W.
Published: September 2010

The detailed syntheses of 3‐deoxy‐D‐arabino‐ and 3‐deoxy‐D‐lyxo‐heptulosonic acids are described. The arabino isomer was purified by LLC on cellulose. In the arabino series an enolized 2‐keto‐1,4‐lactone and in both the arabino and lyxo series 2‐keto‐imido‐1,4‐lactones were isolated. The chemical and spectroscopic properties of these compounds are discussed. A number of other derivatives are described. The UV spectra of the semicarbazones of 2‐keto‐acids and their lactones or esters are discussed. The structure of a quinoxaline derivative of the 3‐deoxy‐D‐arabino‐heptulosonic acid has been studied.
Model studies for enzyme inhibition. Part II: The stereospecific reaction of isopropyl p‐nitrophenyl methylphosphonate with α‐cyclodextrin in aqueous alkaline media
Authors: van Hooidonk C. , Groos Christine C.
Published: September 2010

The rates of alkaline hydrolysis of the enantiomers of isopropyl p‐nitrophenyl methylphosphonate have been measured with and without varying concentrations of α‐cyclodextrin (cyclohexa‐amylose) in aqueous 1.0 M KCl solution at 25° in order to determine the origin of the acceleration of phosphate ester hydrolysis by cyclodextrins.

The observed kinetics can be analyzed in terms of a non‐stereospecific binding of both enantiomers to α‐cyclodextrin prior to a nucleophilic reaction of α‐cyclodextrin predominantly with the (R)‐(‐)‐enantiomer. Dissociation constants (Kdiss) of the inclusion complexes and rate constants (k2) of the nucleophilic reaction are reported for the (R)‐(‐)‐enantiomer in dilute alkaline media.

From the pH‐dependency of the rate of hydrolysis of the (R)‐(‐)‐enantiomer a kinetic pKa value of 12.6 has been evaluated for the ionization of α‐cyclodextrin.

The results also support the suggestion—proposed in the first paper of this series—to use the α‐cyclodextrin‐organophosphorus compound system as a simple model for inhibition of cholinesterases by organophosphorus compounds.
Studies on polypeptides. Part IX: Combination of solid‐phase and classical methods of peptide synthesis in the preparation of 1‐13[13‐Leucine] bovine pancreatic ribonuclease
Authors: Visser S. , Raap J. , Kerling K. E. T. , Havinga E.
Published: September 2010

Merrifield's solid‐phase method was applied to the synthesis of all‐L‐glutamyl‐arginylglutaminylhistidylleucine. Azide coupling with all‐L‐Na,Nϵ‐di‐t‐butoxycarbonyllysyl‐γt‐butylglutamylthreonylalanylalanylalanyl‐Nϵ‐benzyloxy‐carbonyllysylphenylalanine hydrazide also prepared on a solid support

S. Visser, J. Roeloffs, K. E. T. Kerling and E. Havinga, Rec. Trav. Chim. 87, 559 (1968).

, resulted in the N‐terminal tridecapeptide sequence of bovine pancreatic ribonuclease in which the methionyl residue, in position 13, has been replaced by leucine. The deblocked and purified product proved to be identical with a sample prepared using conventional methods exclusively.
Inclusion compounds. Part III: Thiourea adducts of some types of cyclohexane derivatives
Authors: van Bekkum H. , Palm J. H. , Verkade P. E. , Wepster B. M.
Published: September 2010

This paper presents the repeat periods of some thirty cyclohexane derivatives, in their respective thiourea adducts as determined by X‐ray diffraction and elemental analysis. In general,trans‐1,4‐substituted cyclohexanes are found to occupy longer sections of the thiourea channel than the correspondingcis‐isomers. In some thiourea adducts the thiourea lattice is deformed as shown by X‐ray data.
Functionalized enamines. Part VIII: Application of dienamines in the synthesis of 6,7‐diazasteroids and polynuclear heterocycles
Authors: Pollmann M. J. M. , Pandit U. K. , Huisman H. O.
Published: September 2010

6,7‐Diazasteroidal systems (4a,b) have been prepared by the reaction of dienamines 2a,b with m‐methoxybenzenediazonium fluoroborate in one practical step. The reaction also yields hydrazones 5a,b and 6a,b, as by‐products, which have been converted into certain quinoline (14a, b) and indole (20) derivatives, respectively. Diazasteroid 4a was transformed to 6,7‐diaza‐11‐oxoequilenin‐3‐methyl ether (13).
A novel synthesis of trichloromethyl sulfides
Authors: Kloosterziel H. , van der Ven S.
Published: September 2010

Generation of trichloromethyl anion in the presence of thiosulfonates R′SO2SR yields the trichloromethyl sulfides Cl3CSR and sulfinate ion.
Conformation of non‐aromatic ring compounds: Part 63. Conformational equilibrium in trans‐1, 2 dihalogenotetralins
Authors: Buys H. R. , Leeuwestein C. H.
Published: September 2010

The conformational equilibrium in trans‐1,2‐dichloro‐ (I), trans‐2‐bromo‐1‐chloro‐ (II) and trans‐l,2‐dibromotetralin (III) is studied with the aid of dipole moments, NMR, infrared and Raman spectroscopy. It appears that the diaxial conformer strongly predominates in solution. The trend in ΔG° on replacing bromine by chlorine as the substituent or carbon tetrachloride by benzene as the solvent is the same as previously found in other vicinal dihalogeno‐substituted compounds. From the IR and Raman spectra it appears that the three compounds crystallize in the diaxial conformation.
Dielectric constant of binary systems. I: An apparent anomaly in the behaviour of ϵ for mixtures of benzene derivatives: Part of this subject matter was presented at the 52nd. Meeting of the asociación física Argentina, July 30, 1969. La Plata, Argentina: (Preliminary Communication)
Authors: Barón Máximo , Rovira Marta , Varela Margarita
Published: September 2010

The dielectric constant as a function of concentration in binary mixtures of (alkyl)benzenes containing toluene as one component was found to be best represented by a 4th. rank polynomial, differing from the generally accepted behaviour of non‐polar liquid mixtures that are represented by a 2nd. rank polynomial.
Alkylation of enolate anions formation of enol ethers
Authors: Heiszwolf G. J. , Kloosterziel H.
Published: September 2010

The alkylation of ambident enolate anions ‐ obtained from aliphatic ketones (and one particular type of aldehyde) ‐ has been studied using various solvents, bases, alkylating agents and substrates. Alkylation with a reactive alkylating agent (dialkyl sulfates, triethyloxonium fluoroborate) in an aprotic polar solvent (e.g. dimethyl sulfoxide) yields mainly enol ethers, the products of alkylation at oxygen. The predominance of alkylation at oxygen over alkylation at carbon in these fast reactions and the behaviour of the various enolate anions are interpreted with the aid of the principle of least motion.
Dynamic Jahn‐Teller effect in the excited states of SeCl62−, SeBr62−, TeCl62− and TeBr62−: Interpretation of electronic absorption and Raman spectra
Authors: Stufkens D. J.
Published: September 2010

Although the complex‐ions SeCl62−, SeBr62−, TeCl62− and TeBr62− are regular octahedral, the infrared spectra show that some evidence is present for vibronic coupling between ground state and first excited state (dynamic second order Jahn‐Teller effect).

The electronic absorption spectra are reported and assignments given. The splittings of the absorption bands closely resemble those found in the spectra of the alkali halide phosphors (KCl: Tl+ etc.). As for the phosphors, an explanation is given in terms of a dynamic Jahn‐Teller effect in the excited states.

In connection with this, attention is paid to the unusual intensities of the Jahn‐Teller active modes (eg and t2g) in the Raman spectra of these complex‐ions.
Stereospecific reactions of aryl‐substituted acetylenes in strong proton acids, formation of homocyclopropenyl cations
Authors: Lodder A. E. , Buck H. M. , Oosterhoff L. J.
Published: September 2010

Tetra‐arylcyclobutenyl cations are formed in quantitative yield in the reaction of diarylacetylenes with strong proton acids. NMR and UV measurements give evidence of a stereospecific cycloaddition reaction of the diarylacetylenes.

SCF calculations according to Pariser, Parr and Pople show, that homo‐conjugation must exist in the tetra‐arylcyclobutenyl cations.
Conformation of non‐aromatic ring compounds. Part 67. 220 Mc/s NMR spectra of some six‐membered hetero‐rings having a ‐CH2‐CH2‐CH2‐ fragment
Authors: Buys H. R.
Published: September 2010

From the 220 Mc/s NMR spectra of 2‐p‐chlorophenyl‐1,3‐dioxane (I), 2‐phenyl‐1,3‐oxathiane (II) and ‐dithiane (III), trimethylene sulfite (IV) and 2‐oxo‐2‐phenoxy‐1,3,2‐dioxaphosphorinane (V) the spin‐spin splitting pattern of the ‐CH2‐CH2‐CH2‐ fragment of the ring is analyzed. The various types of coupling constants (geminal, vicinal and long‐range) are discussed.
Sulfur compounds in free radical reactions. Part IV. Induced decomposition of arenediazothiolates
Authors: van Zwet H. , Reiding J. , Kooyman E.C.
Published: September 2010

Product distributions and rate data of the thermal decomposition of a diazothiolate (Ar‐NNSR) in benzene, chlorobenzene and nitrobenzene as a function of initial diazothiolate concentrations show the reaction to be complex. Three different types of radical‐induced decomposition are discussed.
Complexes with ligands containing the carbonyl group. Part III: Metal (II) acetaldehyde, propionaldehyde and benzaldehyde solvates
Authors: Driessen W.L. , Groeneveld W.L.
Published: September 2010

Twenty‐two new coordination compounds are reported with acetaldehyde, propionaldehyde and benzaldehyde as the ligands, viz. M(CH3CHO)6(In‐Cl4)2, M(CH3CHO)6(FeCl4)2, M(C2H5CHO)6(InCl4)2 and M(C6H5CHO)6(In‐Cl4)2 with M is Mg, Mn, Fe, Co, Ni and (except for acetaldehyde) Zn.

In the complexes the carbonyl stretching vibration is shifted to lower frequencies compared with this vibration in the free ligands. The magnitudes of the 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 acetaldehyde and propionaldehyde solvates a metal‐dependent absorption band appears in the far infrared, which is attributed to the metal‐ligand stretching vibration. This band was not observed in the benzaldehyde solvates.

Investigation of ligand field spectra indicated 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.

A possible relationship between the groups attached to the CO group and the values obtained for the spectrochemical parameter Dq is described.
The influence of solutes on the liquid‐junction potential in the determination of pH in mixtures of an organic solvent and water
Authors: van Veen A. , Hoefnagel A.J. , Wepster B.M.
Published: September 2010

Buffer solutions of organic acids in various methanol‐water and ethanol‐water mixtures have been measured with cells I and II:

equation image

Contrary to the generally held opinion, the liquid‐junction potential of cell I is clearly dependent on the solutes in the mixed solvent with higher percentages of organic solvent. The consequences of this for the determination of dissociation constants in mixed solvents with cell I are discussed.
The crystal and molecular structure of 5,7‐dibromo‐2‐(3,5‐dibromo‐2‐hydroxyphenyl)‐2‐methoxymethoxy‐3(2H)‐benzofuranone
Authors: Leenhouts J.I.
Published: September 2010

The compound crystallizes in space group P1, with a = 9.96, b = 8.38 and c= 11.77 Å; α = 73.4, β = 81.3 and γ = 83.5°. There are 2 molecules, related by the centre of symmetry, in the unit cell. Single‐crystal diffractometer, heavy‐atom method and least‐squares refinement were employed. Since only badly shaped crystals could be obtained, interatomic distances and angles are not very accurate. However, the investigation was intended merely to determine the molecular structure. The final weighted R factor is 9.0%, including 1635 three‐dimensional reflections.
Aryl dichloromethyl ethers
Authors: Holsboer D. H. , Scheeren J. W. , van Der Veek A. P. M.
Published: September 2010

Aryl dichloromethyl ethers, hitherto practically unknown compounds, are prepared in high yields from aryl formates using PCl5 or dichloromethyl methyl ether as chlorinating agents.
Nucleophilic displacements at halogen in 1‐chloro‐, 1‐bromo‐ and 1‐iodo‐1‐alkynes: I. Thiolates as nucleophiles
Authors: Verploegh M. C. , Donk L. , Bos H. J. T. , Drenth W.
Published: September 2010

Second‐order rate constants,k2, of reactions of thiolates with several 1‐aryl‐2‐halogenoacetylenes and 1‐halogeno‐2‐(2‐thienyl)acetylenes were measured in methanol‐water mixtures. Formeta‐ andpara‐substituted 1‐bromo‐2‐phenyl acetylenes these rate constants correlate well with Hammett σ constants: p 1.15. Linear correlations were observed between logk2and pKaof the corresponding thiols.

The nucleophilicity constants,n, for substitution on bromine and iodine appear to be quite different from those for substitution on other atoms like carbon, sulfur and platinum. It was possible to correlate all the rate constant withEandHin the oxibase scale ofEdwards.
Proton magnetic resonance studies of specifically deuterated cyclohexane compounds. Part II. t‐Butylcyclohexane
Authors: Remijnse J. D. , van Bekkum H. , Wepster B. M.
Published: September 2010

The preparation and PMR investigation of some specifically deuterated t‐butylcyclohexanes is reported. The chemical shifts of the various ring protons and the vicinal axial‐equatorial coupling constants have been determined accurately. The coupling constants show that an equatorial t‐butyl group distorts the chair conformation of cyclohexane: the t‐butyl side of the ring is somewhat puckered. The chemical shifts of the ring protons of t‐butylcyclohexane differ from those of cyclohexane. In consequence the use of a t‐butyl group as a holding group in conformational analysis is not always justified.

A long range coupling of 1.4 Hz is observed between 1,3‐diequatorial ring protons. This partly explains the complexity of the spectra of apparently simple spin systems of other cyclohexane derivatives.

The dehydration of 3‐t‐butylperdeuterocyclohexanol using D3PO4 gives rise to a mixture of the three t‐butylperdeuterocyclohexenes. The intermediate formation of a protonated four‐membered ring is proposed in order to explain the presence of deuterium in the t‐butyl group of only 1‐t‐butylperdeuterocyclohexene.
A gas‐chromatographic investigation of the thermodynamics of solutions of some normal and branched alkanes, cyclohexane, benzene, and tetrachloromethane in apiezon M
Authors: Hammers W.E. , de Ligny C.L.
Published: September 2010

From retention volumes, determined over a wide range of temperatures, solute molar volumes, and fugacities of the solute vapours, standard partial molar free enthalpies and entropies and enthalpies of mixing in infinitely dilute solution in apiezon M were calculated at a range of temperatures.

The residual standard partial molar free enthalpies and entropies and the standard partial molar enthalpies of mixing of the normal and branched alkanes were interpreted with the (simplified) Prigogine solution model, those of the normal alkanes. cyclohexane. benzene, and tetrachloromethane with the solution theory of Flory, Orwoll, and Vrij.
Vibrational spectra of (CH3)2S, CH3SCD3, and (CD3)2S
Authors: Ypenburg J.W. , Gerding H.
Published: September 2010

Infrared absorption and Raman spectra of (CH3)2S, CH3SCD3, and (CD3)2S have been recorded and assigned.
Formation of p‐vinylguaiacol oligomers in the thermal decarboxylation of ferulic acid
Authors: Klaren‐De Wit M. , Frost D.J. , Ward J.P.
Published: September 2010

p‐Vinylguaiacol synthesized by decarboxylation of ferulic acid [3‐(4‐hydroxy‐3‐methoxyphenyl)propenoic acid] with copper powder in refluxing quinoline was accompanied by oligomers. A dirtier and a trimer were isolated and identified as linear oligomers coupled head‐to‐tail. The trimer was a I:I mixture of (R,R + S,S) and (R,S + S,R) forms, according to its 220 MHz NMR spectrum.
Unconventional nucleotide analogues. VI. Synthesis of Purinyl‐ and Pyrimidinyl‐Peptides
Authors: de Koning H. , Pandit U.K.
Published: September 2010

Homogeneous and heterogeneous peptides have been synthesized from pyrimidinyl‐ and purinyl‐amino acids la, b, c. Investigation of the oligopeptide derived from 1a (poly‐1a) showed no secondary structure as a result of base‐base interaction: however, the polymer was found to complex weakly with poly‐adenylic acid. Poly‐1a also exhibited a stimulation of phenylalanine incorporation in the in vitro synthesis of poly‐phenylalanine.
Cobalticenium salts. I: Reaction of cobaltocene with hydrogen halides and with triphenylphosphonium halides
Authors: van Den Akker M. , Jellinek F.
Published: September 2010

Reaction of cobaltocene with hydrogen halides HX (X = Cl, Br, I) in ethereal solution yields the ionic complexes [Cp2Co]+2[CoX4]2− in high yields. If triphenylphosphine is present in the reaction mixtures, the cobalticenium halides [Cp2Co]X are formed as the main products. Reaction of cobaltocene with hydrogen fluoride gives [Cp2Co][HF2]. The mechanisms of these reactions are discussed.
Vinyl orthoformates and vinyl acetals. Part I: Synthesis of divinyloxymethyl and diaryloxymethyl halides and carboxylates
Authors: Scheeren J.W. , van Melick J.E.W. , Nivard R.J.F.
Published: September 2010

Diaryloxymethyl halides and divinyloxymethyl halides, formates, trichloro‐acetates, monochloroacetates, and acetates have been synthesized from corresponding vinyl orthoformates.
Deazapurine derivatives. IX: Synthesis of (7‐substituted)‐1‐, 2‐ and 3‐β‐D‐ribofuranosyl‐vic‐triazolo [4,5‐b]pyridines. 1‐Deaza‐8‐aza‐adenosine and related compounds
Authors: de Roos K. B. , Salemink C. A.
Published: September 2010

The direct condensation of 7‐chloro‐vic‐triazolo[4,5‐b]pyridine (I) with 2,3,5‐tri‐O‐benzoylribofuranosyl chloride (III) in nitromethane containing potassium cyanide, afforded two isomeric blocked nucleosides. Debenzoylation of these products gave the ribosides 7‐chloro‐3‐β‐D‐ribofuranosyl‐vic‐triazolo[4,5‐b]‐pyridine (VI) and its 2‐ribosylated isomer VII. From the reaction of the chloromercuri derivative ofvic‐triazolo[4.5‐b]pyridine (X) with III in boiling toluene, followed by subsequent debenzoylation of the reaction products, three isomeric ribosides were obtained: 1‐, 2‐ and 3‐β‐D‐ribofuranosyl‐vic‐triazolo[4,5‐b]‐pyridine (XVI, XV and XIV). The position of attachment of the sugar moiety to thevic‐triazolo[4.5‐b]pyridine ring system and the assignment of anomeric configuration for all nucleosides reported, are discussed. A number of 7‐substituted 3‐β‐D‐ribofuranosyl‐vic‐triazolo[4,5‐b]pyridines ‐ including 1‐deaza‐8‐aza‐adenosine (XXVI) ‐ was obtained by replacement of the chloro group of VI.
Specific tritium labelling of naphthalene and 1,2,3,4‐tetrahydronaphthalene: A comparison of the hydrogenolysis of phenyltetrazolyl ethers and halogeno compounds with different palladium catalysts
Authors: den Hollander W. , van der Jagt P. J. , van Zanten B.
Published: September 2010

An investigation was carried out on the specific tritium labelling of naphthalene and 1,2,3,4‐tetrahydronaphthalene (tetralin), using tritium gas as one of the reactants. It was demonstrated that specific labelling of naphthalene with deuterium or tritium was possible by catalytic hydrogenolysis of phenyltetrazolyl ethers as well as by catalytic dehalogenation of halogeno compounds, but dehalogenation gave better chemical and isotopic yields. Specific labelling of tetralin was attained only by dehalogenation with a palladium on carbon catalyst in the presence of potassium hydroxide.
Ring transformations in reactions of heterocyclic compounds with nucleophiles (V): Conversion of pyrimidine into 5‐ethyl‐2‐methylpyridine: (Preliminary communication)
Authors: van der Plas H. C. , Jongejan H. , Geurtsen G. , Vollering M. C.
Published: September 2010

Pyrimidine is converted by heating with aqueous methylamine or ammonia at 190° into 5‐ethyl‐2‐methylpyridine (5‐10%).
Purification of relatively stable compounds by partial thermolysis using a ‘tube flow’ reactor
Authors: Tinkelenberg A. , Louw R. , Kooyman E. C.
Published: September 2010

The practical possibilities of a tubular reactor are evaluated, aiming at the isolation of unreacted, relatively stable compounds from mixtures with more reactive contaminants. The system approaches ideal ‘tube flow’ behaviour closely enough to make the method useful on a preparative scale.
Aromatic sulfonation. Part 30: Sulfonation of anthracene with sulfur trioxide‐dioxane; slow proton transfer in the formation of 9‐anthracenesulfonic acid
Authors: Koeberg‐Telder A. , Cerfontain Hans
Published: September 2010

Sulfonation of anthracene‐9‐d with sulfur trioxide‐dioxane in dioxane as solvent at 40° leads to 31 ± 2% α‐, 8 ± 2% β‐ and 61 ± 2% meso‐substitution. The substitution at the meso‐position proceeds with a maximal substrate kinetic isotope effect of hydrogen ‐ kH/kD = 6.8 with 5.6 and 8.6 as limiting values ‐ indicating that the proton removal from the σ‐complex is rate‐limiting.

From the data for anthracene‐9‐d it was calculated that the sulfonation of C14H10 leads to 21 ± 3% 1‐, 6 ± 2% 2‐ and 73 ± 5% 9‐substitution.
Alcohols as ligands. Part II: Metal(II) salts containing coordinated methanol
Authors: van Ingen Schenau A. D. , Groeneveld W. L. , Reedijk J.
Published: September 2010

A number of complexes of the general formula M(CH30H)2+6 (Anion)−2 is reported, the anions being ClO−4, BF−4, NO−3. The cations are Mg, Mn, Co, Ni Zn and Cd, which are completely solvated by methanol in these complexes.

The compounds are prepared by reaction of the metal hydrates with trimethyl orthoformate. Information about the structure of the complexes was obtained from chemical analyses, infrared spectra, ligand‐field spectra, X‐ray powder diagrams and NMR measurements.

Three other compounds of the formula M(CH3OH)3SO4 are reported, with the cations Ni, Co and Zn.
The nature of the s‐s bonds in different compounds II The crystal and molecular structure of diphenyl disulfone
Authors: Kiers C. Th. , Vos Aafje
Published: September 2010

The crystal structure of diphenyl disulfone has been determined by X‐ray diffraction at room temperature. Observed (average) values for the bonds involving a sulfur atom are: S  S  2.193(1), SO  1.428(1), SC  1.753(1) Å. In parentheses the standard deviations for the individual bonds are given.
Synthesis of 1‐phenyl‐1,3‐propano‐2‐indanone
Authors: Fransen‐Zeilstra E. M. , Hall G. E. , Ward J. P.
Published: September 2010

When benzene is refluxed with aluminium chloride one of the products formed after autoxidation is a crystalline ketone. This ketone has been identified as 1‐phenyl‐1,3‐propano‐2‐indanone by a five‐step synthesis starting from l‐phenyl‐2‐indanone. Elimination reactions from intermediate Br‐substituted cyclohexanone derivatives, and a photoelimination from a substituted 2‐indanone are described.
The coordination chemistry of phosphoryl compounds containing the ‐N(CH3)2, group. Part VI: Complexes of hexamethylphosphoramide and nonamethylimidodiphosphoramide with metal perchlorates
Authors: de Bolster M. W. G. , Groeneveld W. L.
Published: September 2010

A number of new perchlorate complexes of the ligands hexamethylphosphoramide and nonamethylimidodiphosphoramide is reported.

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

A number of complexes which were reported earlier by other workers, were reprepared and their properties were studied with the aid of X‐ray powder measurements, infrared and ligand‐field spectra. In some cases this leads to quite different conclusions, which are supported by the results found for the new complexes.

The raman spectrum of nonamethylimidodiphosphoramide is reported for the first time and it is shown that this facilitates the assignment of absorption bands in the complexes.

It is pointed out that planarity of the six‐membered ring magnified image, which is in some way suggested by infrared and raman measurements might explain the unusual stability of complexes with the ligand nonamethylimidodiphosphoramide.
The infrared spectra of linear primary mono‐ and skipped polyacetylenic alcohols and bromides
Authors: Bus J. , Memelink A. A.
Published: September 2010

The infrared spectra of 2‐alkynyl, 2,5‐alkadiynyl and 2,5,8‐alkatriynyl bromides and alcohols are discussed.

These types of acetylenic compounds can easily be differentiated in the 1100‐1150 cm1 region and to a lesser extent in the 2200‐2300 cm−1 region.
A convenient synthesis of L‐1‐methylhistidine and L‐1‐ethylhistidine
Authors: Beyerman H. C. , Maat L. , van Zon A.
Published: September 2010

Alkylation of the easily accessible methyl ester of L‐Na,3‐dibenzoylhistidine with the aid of trimethyl‐ and triethyloxonium fluoroborate followed by decomposition with water and acid hydrolysis yielded L‐1 ‐methyl‐ and L‐1‐ethylhistidine respectively. Comparison with natural L‐1‐methylhistidine confirmed the structure and optical purity.
Reactions of 1‐Dodecene with a novel reaction product of formaldehyde and sulfur trioxide
Authors: Nooi J. R. , Martens R. J. , Kemper H. C.
Published: September 2010

A 1 : 1 CH2O/SO3 product has been prepared from sulfur trioxide and trioxane or paraformaldehyde in 1,2‐dichloroethane, which was different from methylene sulfate (a 1 : 1 CH2O/SO3 compound described in the literature).

In contrast to methylene sulfate, the CH2O/SO3 product reacts with 1‐dodecene in 1,2‐dichloroethane at 10°C. The main reaction leads mainly to organic sulfates. The structures of the sulfates indicate that the CH2O/SO3 compound mainly reacts similar to a formaldehyde/(Lewis) acid complex (Prins‐type reaction). The major side‐reaction leads to sulfonates. This side‐reaction is similar to the reaction of 1‐dodecene with the dioxane/SO3 complex. Other side‐reactions are acid‐catalysed isomerizations and addition of sulfonic acids and organic sulfates to 1‐dodecene to give alkyl alkanesulfonates and dialkyl sulfates.
The standard potentials of the silver/silver bromide and of the silver/silver iodide electrode in some organic solvents and their mixtures with water
Authors: Bax D. , de Ligny C. L. , Alfenaar M. , Mohr N. J.
Published: September 2010

The standard potentials at 25° of the Ag, AgI electrode in ethanol and ethanol‐water mixtures, of the Ag, AgBr and Ag, AgI electrodes in acetone‐water mixtures and one dioxane‐water mixture and of the Ag, AgBr electrode in 100% acetone have been determined by comparison with the known standard potentials of the Ag, AgCl electrode in these solvents.
Activation and transfer of oxygen. V. Spontaneous oxidation of 1,3,10‐trimethyl‐5,10‐dihydroalloxazine in acidic media in connection with its hydroxylating ability
Authors: Mager H. I. X. , Berends W.
Published: September 2010

On autoxidation several dihydroalloxazines show a strong hydroxylating ability without addition of metal compounds. The assumption in the literature that N1 ‐alkylated dihydroalloxazines (I) cannot activate oxygen was proved to be wrong. The material balance was studied both in the absence and in the presence of phenylalanine as a substrate. Both autoxidation and hydroxylation to tyrosines were in agreement with calculations based on a theory which has already been put forward.

Hydroxylation of organic compounds may be inhibited by some inorganic anions. An explanation is given for the inhibition occurring in hydrochloric acid.
Deazapurine derivatives. X: Synthesis and reactions of 5,7‐disubstituted imidazo[4,5‐b]pyridines
Authors: Schelling J. E. , Salemink C. A.
Published: September 2010

A new synthesis for 5,7‐dichloroimidazo[4,5‐b]pyridine is described. From this compound and 5‐amino‐7‐chloroimidazo[4,5‐b]pyridine a number of 5,7‐disubstituted imidazo[4,5‐b]pyridines are prepared, including 7‐aminoimidazo[4,5‐b]pyridin‐5‐one, the 1‐deaza analogue of isoguanine.
Transition points in solid antimony trichloride
Authors: Julien W. M. C. , Gerding H.
Published: September 2010

A dilatometric investigation of solid antimony trichloride in the temperature range‐50° to +71 °C shows the presence of second order transition points at 63.5 and 70°. Raman spectra recorded at −150, −50, 0, +50, +67 and +70° show only minor changes in frequency shifts and in line intensities, except for the appearance of a 134 cm frequency shift at 67°, which is also present at 70° (solid) and in the liquid. Possible changes in intermolecular interaction, especially at the first transition point, are discussed.
Composition of polifungin, a new antifungal agent
Authors: Porowska N. , Halski L. , Płóciennik Z. , Kotiuszko D. , Morawska H. , Kowszyk‐Gindifer Z. , Bojarska‐Dahlig H.
Published: September 2010

Polifungin is a new tetraene antibiotic complex with antifungal activity. It has been shown that four biologically active components are present in this complex, polifungin B being the main component differentiating polifungin from nystatin.
Total synthesis of modified 6‐thia‐estrogens
Authors: Könst W. M. B. , van Bruynsvoort J. , Speckamp W. N. , Huisman H. O.
Published: September 2010

6‐Thiasteroids have been totally synthesized by reacting 2‐substituted cyclopentane‐1,3‐diones with 4‐hydroxy‐4‐vinyl thiachromanes or with the derived isothiouronium salts. Modifications of the C(13)‐substituent have also been carried out via the thallium salt of the C18‐nor‐8,14‐seco‐steroid. When using 2‐chloro‐ and 2‐acetylamino‐cyclopentane‐1,3‐diones anomalous reaction products were obtained.
Relation between structure and cholinergic activity. I. Synthesis and muscarinic activity of 5‐alkyl‐2‐methyl‐4‐trimethylammoniomethyl‐1,3‐dioxolane iodides
Authors: Elferink J. G. R. , van Noordwijk J. , Schreurs W. H. P. , Salemink C. A.
Published: September 2010

The preparation and muscarinic activities of a number of 5‐alkyl substituted analogues of the dioxolane of Fourneau are described. Muscarinic activity decreases rapidly when the alkyl chain lengthens, moreover a change from parasympathomimetic into parasympatholytic activity occurs. The stereochemical aspects with regard to the 5‐position are considered. The synthesis and cholinolytic effect of 2‐methyl‐c‐5‐propyl‐r‐4‐trimethylammoniomethyl‐1,3‐dioxolane iodide and the corresponding 4,5‐transcompound are described.
Substituent effects of meta and para alkyl groups on the charge transfer band in the UV spectrum of nitrobenzene
Authors: Baas J. M. A. , Wepster B. M.
Published: September 2010

The wavenumbers of the charge transfer band maxima in the UV spectra of a large number of 3‐, 4‐, 3,4‐, and 3,5‐alkyl‐substituted nitrobenzenes have been determined in isooctane and in ethanol. Extinction coefficients ϵmax and oscillator strengths are reported for a number of these compounds. The differences VHmax‐VRmax in isooctane reveal an order of substituent effects of alkyl groups which is not entangled with differential solvation effects. Methyl groups in the γ‐position of 4‐alkyl groups are very effective in stabilising the excitation. There is no constant ratio between the substituent effects of the alkyl groups from the 3‐ and the 4‐position. The substituent effects are approximately additive in the 3,4‐ and 3,5‐dialkyl‐substituted nitrobenzenes. Both 3‐ and 4‐alkyl groups bulkier than methyl exert a steric hindrance of the solvation in ethanol; this hindrance has been quantified for the 4‐alkyl groups.
Investigations on organogermanium compounds. XIII: Synthesis of linear peralkylpolygermanes. Mechanism of the reaction of trialkylgermyl alkali metal compounds with trialkylhalogenogermanes
Authors: Bulten E. J. , Noltes J. G.
Published: September 2010

A full report is given of our investigations into the synthesis of a series of linear peralkylpolygermanes, both by reacting organohalogenogermanes with alkali metals and by coupling of organohalogenogermanes with trialkylgermyl alkali metal compounds2–4. The latter type of reaction always gives in addition to the asymmetric compound R3GeGeR3′, varying amounts of the symmetrical products R6Ge2 and R6′Ge2. Evidence is presented that these side‐products are formed by a nucleophilic cleavage of the GeGe bond of the primary asymmetrical coupling products, rather than by a halogen‐metal exchange reaction.