bluuebunny/crossref_metadata_2025 huggingface dataset:
Stereospecific Synthesis of Z and E C16ω‐Iodo Δ9 Fatty Acids from Natural Aleuritic Acid
Authors: Hevesi L. , Hontoy J. , Krief A. , Lubochinsky J. , Lubochinsky B.
Published: September 2010

Long chain fatty acids containing iodine were found to be convenient label compounds for the studies of membrane incorporation. We describe the stereospecific synthesis of Z and E C16ω‐iodo Δ9 fatty acids and esters starting from commercially available aleuritic acid. Chemical and spectroscopic proofs of stereospecificity are given for one of the compounds.
1H‐NMR Study of the Di‐Glucopyranoses in D2O
Authors: De Bruyn A. , Anteunis M. , Verhegge G.
Published: September 2010

We report the analysis at 300 MHz of the 1H‐n.m.r. spectra of all the α‐D‐, and β‐D‐glucopyranosyl‐ (1 → x) ‐D‐glucopyranoses (x = 1, 2, 3, 4 and 6) in D2O (CHART 1, 1‐9). Chemical shifts were compared with those of α‐D‐, and β‐D‐glucopyranose. Using homo‐INDOR experiments and applying increment rules it was possible to identify all the resonances of the individual protons and to assess the position of the glycosidic linkage. All protons situated on, or vicinal to carbons involved in this linkage, are shifted downfield. Exceptions occur for the glycosidic proton belonging to the non‐reducing parts.
A New Synthetic Approach to 4‐Hydroxybenzofuran and 5‐Hydroxychroman Derivatives
Authors: Verhé R. , Schamp N. , De Buyck L. , De Kimpe N. , Sadones M.
Published: September 2010

4‐Hydroxybenzofuran and 5‐hydroxychroman compounds have been synthesized by heating 2‐chloro‐2‐alkenyl‐1,3‐cyclohexanediones, prepared by chlorination of 2‐alkenyl‐1,3‐cyclohexanediones with N‐chlorosuccinimide, in dimethylformamide ‐25% hydrogen chloride at 140°C.
Revised Synthesis of 3‐O‐Cinnamyl‐, 3‐O‐p.Coumaryl‐and 3‐O‐Isoferulyl‐D‐(‐)‐Quinic Acid
Authors: De Pooter H. , De Brucker J. , van Sumere C. F.
Published: September 2010

The experimental circumstances for the synthesis of 3‐O‐acyl‐D‐(‐)‐quinic acids by the procedure of Haslam et al are improved, and applied to the preparation of the title compounds. The substances are obtained in overall yields of respectively 36%, 25% and 20%, comparing favourably with the reported results of respectively 8%, 7% and 6.5%.
The Variation of Lattice Parameters with Composition in Solid Solutions of Hydroxylapatite and Fluorapatite
Authors: Schaeken H. G. , Verbeeck R. M. H. , Driessens F. C. M. , Thun H. P.
Published: September 2010

Solid solutions of hydroxylapatite (OHA) and fluorapatite (FA) were prepared from CaCO3, CaHPO4.2H2O and CaF2 by solid‐state reaction at 1000°C in a stream of nitrogen which was saturated with water vapor at 0°C. Determinations of the lattice parameters were carried out by step scanning of certain X‐ray reflections. It was found that the value of the lattice parameter a varied linearly with the fluoride content. No segregation into two apatite phases was observed, when solid solutions were heated at 250°C for 300 hours. The consequences of this study for the behaviour of these solid solutions in contact with aqueous solutions are discussed. Thereby, attention is focussed on the caries‐preventive action of fluoride ions.
Metal Clusters in Catalysis III. — Clusters as Models for Chemisorption Processes and Heterogeneous Catalysis
Authors: Muetterties E. L.
Published: September 2010

An analysis of the intrinsic structural, stereochemical and thermodynamic features of metal surfaces vis a vis those of discrete metal clusters suggests that the clusters are attractive models of metal surfaces for chemisorption and heterogeneous catalysis. Chemical and catalytic properties of the two classes are compared.
Prototropie des oxadiazoline‐1,2,4 ones‐5 et thiones‐5
Authors: van Haverbeke Y. , Maquestiau A. , Muller R. N. , Stamanne M. L.
Published: September 2010

3‐phenyl‐1,2,4‐oxadiazolin‐5‐one and 3‐p‐chlorophenyl‐1,2,4‐oxadiazolin‐5‐one exist in the N2‐H conjugated form as evidenced by analysis of spectroscopic results (NMR, UV and IR). In the same manner, the data lead to assign the “thione” form to 3‐phenyl‐1,2,4‐oxadiazolin‐5‐thione.
Ionic association and dielectric relaxation of alkylammonium salts in non polar solvents
Authors: Cachet H. , Lestrade J. C.
Published: September 2010

Complex dielectric permittivity measurements of tri and tetra‐alkylammonium salts in C6H6 and CCl4 solutions have been performed in the 8 ‐ 35000 MHz frequency range. Relaxation spectra, corrected for conductivity losses, are nearly half‐circles in the case of tri‐n‐butylammonium picrate while they exhibit a much more complex shape in the case of tetra‐n‐butylammonium salts. For the incompletely substituted salt, the hydrogen bond favours the formation of molecule‐like ion‐pairs and the main relaxation process is the diffusional rotation of such ion‐pairs. For concentrated solutions of tetra‐butylammonium salts, the state of the solute can be pictured as large, non‐rigid aggregates without a permanent dipole moment. The polarization arises from an instantaneous asymmetrical distribution in the positions of the ions under an applied electric field. The complicated shape of the spectra is accounted for by assuming this asymmetry to vanish through the diffusional translation of the ions.
1H‐NMR spectra of pyrazino [2,3‐f] quinoxalines and 5,6‐diaminoquinoxalines
Authors: Nasielski‐Hinkens R. , Benedek‐Vamos M. , Hautain Y. , Nasielski J.
Published: September 2010

The NMR spectra of 2,3‐ and 2,3,8,9‐substituted pyrazino [2,3‐f] quinoxalines are described. Unambiguous deuteriation of 5,6‐diaminoquinoxalines allowed the assignment of the 7‐ and β‐protons; changes in solvent induce inversions in the peak positions.
Étude Par RMN du 13C Du Benzothiazole et de Ses Dérivés Nitrés
Authors: Elguero J. , Faure R. , Vincent E.‐J. , Lazaro R.
Published: September 2010

The C13 assignement of the six carbon atoms of benzothiazol was obtained by comparison with the results for thiazol and from the effect of the nitro‐group in positions 4, 5, 6 and 7 and the effect of deuterium in position 6.
Synthetic Studies on Perhydronaphthacenes
Authors: De Pessemier Fritz , Vanhee Paul , Tavernier Dirk
Published: September 2010

The synthesis of perhydronaphthacenes, by Stork enamine annelation of cis‐2,7‐decalinedione, is described. Stereochemical detail is discussed.
Optical Stability of Organometallic Compounds With a Tin‐Germanium Bond
Authors: Gielen Marcel , Simon Serge
Published: September 2010

(Dimethylphenylstannyl)methyl‐1‐naphthyl‐phenylgermanium (I) and methylneophylphenyl (triphenylgermyl)tin (II) are configurationally stable even in the presence of strong nucleophiles. Optically active isopropylmethylphenyl (triphenylgermyl)tin (III) has been synthesized by asymmetric induction and shows that hexaorganodimetal compounds with a tin‐germanium bond are optically stable.

The synthesis of functionally substituted organometallic compounds with a Sn‐Ge bond, like 5‐[(phenyldimethylstannyl) diphenylgermyl]‐2‐pentanone (VI), is described. An attempted resolution of a cyclohexylmethylphenyl (triorganogermyl)tin compound is also given.
The Influence of White Radiation on Diffraction Data in X‐Ray Analysis. A Comparative Study of Monochromator Versus Filter Data
Authors: Petit G. , Lenstra A. T. H.
Published: September 2010

Using a Mo‐tube two data sets were collected from an ammonium hydrogen malate crystal. The first set was collected using the traditional Zr‐filter. The second one was obtained using a graphite monochromator.

The differences in the corresponding intensities are due to the presence of white radiation in the set of filter data. The refined temperature parameters from both data sets are not exactly comparable. As far as hydrogen positions are concerned differences up to 0.1 Å were found changing from the first to the second data set.

In addition an empirical correction is proposed, which enables one to eliminate the white radiation from the usual filter data.
Infrared Spectra and Structure Of Carbanions ‐ XIV. Isomeric Carbanionic Adducts of Some Substituted Cyano‐Polyenes
Authors: Juchnovski I. N. , Binev I. G.
Published: September 2010

It was found on the basis of IR spectroscopic data, that the nucleophilic CH3O− attack to substituted cyano‐butadienes PhCHCHCHC (X = CN, COOEt, C6H4NO2‐p) and 1‐cyano‐1‐ethoxycarbonyl‐6‐phenyl‐hexatriene takes place at the β‐carbon atom. The 1,2‐carbanionic adducts, thus formed, isomerise spontaneously into the thermodynamically more stable 1, 4‐adducts of the butadiene derivatives and 1,6‐adduct of the studied hexatriene.
Preparation of Cyclopropanes by Reduction With an Alkaline Metal in Liquid Ammonia and Long Range Phenomena in the 1H‐Nmr Spectra of 1, 3‐Dioxane‐Spirocyclopropanic Derivatives
Authors: Breugelmans Micheline , Anteunis Marc J. O.
Published: September 2010

A newly proposed2 modification of an intra Würtz‐coupling procedure has been tested for its preparative value. The 1H‐nmr spectral data of two 1, 3‐dioxane‐spirocyclopropane derivatives (1 and 2) are discussed and the characteristic long range couplings are revealed.
13C NMR Spectra of Electrically Neutral Organic Lewis Acids
Authors: Haslinger E. , Wolschann P.
Published: September 2010

The13C NMR spectra of a number of derivatives of the cyclic acylal of malonic acid and of dimethylbarbituric acid are reported. These compounds contain an electron poor polarized carbon ‐ carbon double bond and act therefore, as Lewis acids.
Solution Conformation of Nigericin Free Acid and Nigericin‐Sodium Salt
Authors: Rodios Nestor A. , Anteunis Marc J. O.
Published: September 2010

High resolution 1H‐nmr spectral data enable us to confirm the close resemblance between the three‐dimensional structure of nigericin free acid and its Na+‐complex. The circular form with a buttoning shut by hydrogen bonding between the head carboxylate and the tertiary alcohol function of the last six‐membered ring is a further typical example how the folded quasi cyclic backbone thus formed enables in these polyetherin ionophores the sequestering of a cation. Further details allow the description of some departure of the ideal chair form in rings A and B. No extra water molecule seems to be present in the free acid state. Whereas the secondary alcohol OH‐10 in the free acid form may participate to the head‐to‐tail connection, this seems not to be the case in the salt. A comparative discussion of the head‐to‐tail buttoning shut pattern in monensin, dianemycin and nigericin is given.
Photoisomerization in α, β‐Unsaturated Carboxylic Acids
Authors: Biot Jean‐Marie , De Keukeleire Denis , Verzele Maurice
Published: September 2010

4‐Methyl‐2‐(E)‐pentenoic acid and 5‐methyl‐2‐(E)‐hexenoic acid are quantitatively transformed into the corresponding β,γ‐unsaturated isomers by irradiation at 254 nm.

The synthesis of 5,5‐dimethyl‐2(5H)‐furanone via photochemically induced lactonization of 4‐hydroxy‐4‐methyl‐2‐(E)‐pentenoic acid is described.
Conformations Privilégiées de Dérivés des Bithiophenes: Étude par Spectroscopie d'Absorption Électronique
Authors: Meunier P. , Coustale M. , Arriau J.
Published: September 2010

An experimental and theoretical study of the UV absorption spectra of bithiophens indicates that non planar conformations are predominant in vapour phase and non polar solutions. The existence of steric strain within dibramobithiophens induces an increase of the twist angle. An evaluation of this angle is carried out for each compound.
Studies on organophosphorus compounds XXI. the dimer of p‐methoxyphenylthionophosphine sulfide as thiation reagent. a new route to thiocarboxamides
Authors: Scheibye S. , Pedersen B. S. , Lawesson S.‐O.
Published: September 2010

The thiation properties of the dimer of p‐methoxyphenylthionophosphine sulfide, 1, has been investigated by performing reactions with a representative series of aliphatic and aromatic primary, secondary, and tertiary carboxamides in the temperature range 80‐100 °C using HMPA as solvent. This new method seems to be superior to all others as in most cases quantitative yields are found. Salicylanilide, when reacted with 1, in HMPA, yields salicylthioanilide and a new type of phosphorus heterocycle, 3, whose structure has been determined by NMR‐and X‐ray analyses. 13C NMR data are tabulated for a series of thioamide carbons.
Studies on organophosphorus compounds XXIV. the formation of disulfides from sulfoxides
Authors: Rasmussen J. B. , Jørgensen K. A. , Lawesson S.‐O.
Published: September 2010

The reaction of DMSO with the dimer of p‐methoxyphenylthionophosphine sulfide, 1, produces dimethyl disulfide and causes partly deoxygenation of DMSO to give dimethyl sulfide. P4S10 and DMSO give dimethyl disulfide in lower yield, a result not observed in recent reports. 5, 6 The cyclic sulfoxide, tetrahydrothiophene sulfoxide, 2, also reacted with 1 to give the cyclic disulfide, 1,2‐dithiane, 3.
Synthesis of Alkylidenetriazenes (1,2,3‐Triazabutadienes). X‐Ray Crystal Structure of 1‐Methylthio‐3‐(α‐Morpholino) Benzylidenetriazene
Authors: L'abbé Gerrit , Willocx André , Declercq Jean‐Paul , Germain Gabriel , van Meerssche Maurice
Published: September 2010

The clean and high yield reactions of sodium azide with quaternary salts of N, N‐disubstituted thioamides furnish alkylidenetriazenes 3 (1, 2, 3‐triazabutadienes) instead of the previously reported2) dihydrothia(SIV) triazoles 2.
Study of Inorganic Salts by Static and Dynamic Secondary Ion Mass Spectrometry
Authors: Marien J. , De Pauw E.
Published: September 2010

Secondary ion mass spectrometry (SIMS) has been applied to the study of superficial layers of solid inorganic salts such as sulfate and sulfite of sodium. The positive and negative SIMS spectra of sulfate and sulfite show qualitatively no difference. Nevertheless, the relative heights of the peaks m/e ▪ 149 and m/e = 165 which are present in both spectra enable a distinction between Na2SO3 and Na2SO4. According as the solid is sulfite or sulfate, the intensity of the (Na3SO3)+ is higher or lower than the intensity of (Na3SO4)+. The positive SIMS spectra can be interpreted according to a model where ejected neighbouring atoms or clusters recombine depending upon their chemical affinity and where molecular species (Na2SO3), (Na2SO4), are cationized by sodium. Reduction of the salts into metallic sodium has also been observed.

In this work, we also demonstrate that the superficial oxidation of sulfite into sulfate can be monitored by SIMS.
The Molecular Structure of 3,5‐Diethoxycarbonyl‐2, 6‐Dimethyl‐1,4‐Dihydropyridine. An X‐Ray Study
Authors: Lenstra A. T. H. , Petit G. H. , Dommisse R. A. , Alderweireldt F. C.
Published: September 2010

The title compound crystallizes in P1, with a = 6.999 Å, b = 7.491 Å, c = 12.711 Å, α = 91.1 °, β = 106.5 °, y = 90.1 ° and Z = 2. The structure was solved by rotation and translation search procedures and refined to a final R‐value of 0.053. Excluding the hydrogen atoms, the molecule is planar. The compound is crystallized in such a way that a close packed layer structure is achieved.

The influence of the packing of the molecules on the reduction of chloranil by 3,5‐diethoxycarbonyl‐2,6‐dimethyl‐1,4‐dihydropyridine in solid state solutions is discussed.
Studies of Australian Soft Corals. XVII . The Isolation and Properties of Lemnalactone, 7‐EPI‐Lemnalactone and their Derivatives. A Correction of Several Literature Assignments, Supported by X‐Ray Diffraction
Authors: Ahond A. , Chiaroni A. , Coll J. C. , Fourneron J. D. , Riche C. , Braekman J. C. , Daloze D. , Tursch B. , Dunstan P. J.
Published: September 2010

The isolation and full evidence for the structure of lemnalactone (1) and 7‐epi‐lemnalactone (2) are reported. Spectroscopic evidence which led to this reinvestigation is presented, and the structural conclusions therefrom are confirmed by a single crystal X‐ray study of a derivative of 2. The previous structure for lemnalactone (as 2) has led to several erroneous stereochemical assignments in the literature and these are here corrected.
Influence of ΔpKa and of the molar volume of the base on the viscosity and on the concentration of conducting ions in binary mixtures of phenols and aliphatic amines
Authors: Huyskens P. L. , Neven L.
Published: September 2010

In this work we measured at 298.2 K the viscosities η, the conductivities κ and the densities of the binary mixtures of 4NO2‐phenol with triethylamine (TEA) and of phenols with lower acidities with dibutylamine (DBA) or tributylamine (TBA). The metastable liquid TEA‐4NO2‐phenol mixtures exhibit a maximal viscosity as high as 8270 cpoise at a mole fraction xA = 0.71 of the acid. Around this mole fraction the mixtures are mainly constituted by conducting ions, as can be deduced from the product κη using Walden's rule as a first approximation. For the systems with the weaker phenols, for which ΔpKa is lower than 2.5, a marked part of the amine is present under the shape of non‐conducting entities and the viscosity maxima are much lower. Passing from the ethyl bases to the butyl bases does not trigger important changes in the height or in the position of the visocosity peaks. The ion concentrations become much smaller, but this effect is cancelled off by the rise of the molar volumes which enhances the viscosity. The drastic drop of the ion concentration in the mixtures when replacing the ethyl groups of the bases by butyl groups is partly due to the decrease of the dielectric constant of the solutions. This results from the diminution of the number of dipoles per unit volume.

Not only the concentration of the conducting ions and their volume determine the viscosity of the mixtures but also the volume of the non‐conducting entities which are present into the solution. The enhancement of the viscosity when passing from dibutylamine to the less bulky triethylamine can be related to the difference in the shape of both molecules.
General models for helicenes
Authors: Navaza J. , Tsoucaris G. , Le Bas G. , Navaza A. , de Rango C.
Published: September 2010

Several geometrical characteristics of 6‐, 7‐, 10‐, 11‐ helicene have been studied: accuracy of the binary axis, distribution of atoms over three helices, bond distances and angles, planarity and interplanar angles of benzene rings, existence of new planar groups. Two types of general models are suggested and discussed: the triple helix and the staircase model.
Analytical and TG, DIG and DTA studies of transition metal complexes of salicylic acid
Authors: Heda B. D. , Khadikar P. V.
Published: September 2010

The complexes of Fe(II), Zn(II) and VO(II) with salicylic acid have been prepared. Composition (ML2.2H2O) and structure of these complexes were established by elemental analyses and IR spectra. The thermal decomposition of these complexes using TG, DTG and DTA together with the analyses of intermediate products gave supporting evidence for the assigned structure. Thermal decomposition starts with dehydration and subsequently the anhydrous complex decomposes into corresponding metal oxide as the end product. Their dehydration temperature Increases with the increase in the coordinated water frequency. Thermal stability of the metal complexes increases in the order Fe>Zn>VO.
Solid ‐ liquid phase transfer catalysis using solid sodium hydroxide in preparative ethers synthesis
Authors: Jm. Dou H. , Delfort B. , Hassanaly P. , Gallo R. , Kister J.
Published: September 2010

Preparative ethers synthesis can be performed using P.T.C. if solid sodium hydroxide is used as basic medium. In this case, side reactions ( eg: hydrolysis or elimination ) are avoided. Moreover, secondary disymetrical ethers can be synthezised starting from an alcohol and a secondary alkyl halide in acceptable yields.
A comparative study of the aggregation, rotational side‐chain isomerism and side‐chain/side‐chain interactions in the cyclic dipeptides c/Phe, Pip/ and c/Phe, (s)Pip/
Authors: Schrooten Rik , Joshi Satish , Anteunis Marc J. O.
Published: September 2010

We compare in this contribution the aggregation and the rotational side‐chain isomerism of the diastereomeric cyclodipeptides phenylalanine‐pipecolic acid (1, 2) with those previously observed1in the parent DKP's, containing the 4‐thiapipecolic acid moieties instead. Concomitantly with dimerisation (C8‐dimer) an increasing folding with concentration of the aromatic nucleus over the DKP‐ring is observed in aprotic solvents. The greater tendency for stacking in the cis‐isomer than in the trans‐isomer is thus reflected by a larger dimerisation capacity of the former. In the carbocyclic congeners the stabilisation of the folded form in the cis‐isomer is less pronounced than for the thia‐analog, thus confirming the surmise that an attractive interaction would occur when sulfur approaches a π‐system in space.
An 1H NMR study of vinblastine
Authors: De Bruyn Andrea , Taeye Leo De , Anteunis Marc J. O.
Published: September 2010

The vicinal coupling constants in the 1H NMR spectrum of vinblastine allow a proposal for the conformation of the catharanthine moiety including the nine‐membered ring.
Selective reduction of α‐keto esters with organotin hydrides application to asymmetric syntheses
Authors: Rahm A. , Pereyre M.
Published: September 2010

Vrganotin hydrides selectively reduce the keto function group in α‐keto esters such as pyruvates or benzoylformates. Hydrostannation of (‐) menthyl benzoylformate with achiral reagents occurs with 5–20% asymmetric induction while the reaction of (−) 2 butyl‐diphenyltin hydride with ethyl benzoylformate only proceeds with a very low optical yield.
Kinetics and Mechanism of Oxidation of DL‐Proline by Manganic Sulphate in Acidic Medium
Authors: Ahmad Iftikhar , Odyek Olwa , Ashraf C. M. , Olal A. D.
Published: September 2010

The kinetics of oxidation of di‐proline by manganic sulphate in the acidic medium have been studied. The reaction is first order with respect to dl‐proline and manganic sulphate and inverse first order with respect to hydrogen ions. A reaction mechanism has been proposed.
Synthese von Heterocyclen unter Verwendung von Phosphoryliden
Authors: Bestmann Hans Jürgen
Published: September 2010

Epoxides, nitril oxides and carbonyl compounds react with alkylidene triphenylphosphoranes by cycloaddition to PV‐heterocycles with a P‐O‐bond. The latter collapse according to a general reaction scheme, among others allowing a new interpretation of the mechanism of the Wittig reaction. Phosphacumulene and phosphaallene ylides are versatile reagents for the synthesis of heterocyclic compounds. A general ringclosure principle for the preparation of heterocycles is described. Cycloaddition onto the CC double bond in phosphacumulene ylides enables the synthesis of four, five and six membered heterocycles in a broad applicability.
Predictability of Proton Chemical Shifts in Polyether Carboxylic Acid Ionophores
Authors: And Frans Borremans , Anteunis Marc J. O.
Published: September 2010

A statistical treatment of 342 chemical shifts from the 1H nmr spectra in chloroform of 17 polyether ionophores allows their prediction with reasonable accurracy (0.14 to 0.17 ppm). The predictions are based on increment values for vicinal gauche and more remote contributions. Some large deviations in shifts may be rationalized in terms of special effects such as “cavity”‐effect and complexation shifts.
Catalytic Properties of Synthetic MoS2 of Varying Surface Areas
Authors: Busetto Luigi , Iannibello Antonio , Pincolini Fabrizia , Trifiró Ferruccio
Published: September 2010

Molybdenum sulfide catalysts of varying surface areas were prepared by thermal decomposition of MoS3 at 300, 350, 400, 450 and 500°. The surface areas has been found to be strongly dependent on the rate of heating suggesting a competition between the rate of nucleation and that of sintering of MoS2. The specific activities toward thiophene hydrodesulfuration and cyclohexene hydrogenation have been studied and their complementary trends have been attributed to the presence of at least two active centers. The catalytic properties and the variable surface area values found for the MoS3‐MoS2 system have been correlated to X‐Ray and analytical data.
Synthèse des 9‐, 10‐ et 11‐Fluoroacronycines
Authors: Smolders Robert René , Waefelaer Adolphe , Coomans Roland , Francart Didier , Hanuise Jean , Voglet Nicole
Published: September 2010

A partir des 5‐, 6‐ et 7‐fluoroisatines, on décrit la synthèse des 9‐, 10‐ et 11‐fluoroacronycines via les 5‐, 6‐ et 7‐fluoro‐1,3‐dihydroxy‐10‐méthylacridan‐9‐ones.
Enzymatic “in Vitro” Reduction of Ketones: Part 9. Preparation of Pure (1S, 2S)‐2‐Chlorocyclohexanol
Authors: Sadozai S. K. , Merckx E. M. , van De Wal A. J. , Lemière G. L. , Esmans E. L. , Lepoivre J. A. , Alderweireldt F. C.
Published: September 2010

The enzymatic “in vitro” reduction of 2‐chlorocyclohexanone in a coupledsubstrate coenzyme recycling system (ketone ‐ ethanol ‐ NAD+ ‐ HLAD) delivers optically pure (1S, 2S)‐2‐chlorocyclohexanol. The optical purity is shown by 19F‐NMR of the (R)‐MTPA esters. The absolute configuration is mainly determined by ORD of the (2S)‐2‐chlorocyclohexanone.
Kinetics and Mechanism of the Ruthenium (III) Catalysed Oxidation of Some Aliphatic and Cyclic Ketones by Periodate Ion in Aqueous Alkaline Medium: A Novel Behaviour of Ruthenium (III)
Authors: Pati Subas C. , Panda Markandeswar
Published: September 2010

Kinetics of ruthenium (III) chloride catalysed oxidation of acetone, ethyl methyl ketone, isobutylmethyl ketone, pentan‐2‐one, cyclopentanone and cyclohexanone by sodium metaperiodate in aqueous alkaline medium at constant ionic strength is reported. The order with respect to [IO‐4] is found to be zero. The order with respect to [substrate] is unity for acetone, ethylmethyl ketone, isobutylmethyl ketone and cyclopentanone, whereas, pentan‐2‐one and cyclohexanone exhibit fractional dependence on substrate, in the entire range of substrate concentration studied. Strikingly, the order with resnect to [ruthenium (III)] is fractional in case of the ketones where substrate dependence is unity and Unity where the substrate dependence is fractional.

The reaction rate increases linearly following a nearly unit dependence on [OH−] at lower concentration of alkali and levels off after a particular [OH−].

The activation parameters have been evaluated. A suitable mechanism has been postulated and rate laws have been deduced.
On the mechanism of the rearrangement of N‐aryl α,α‐dichloroketimines with lithium aluminium hydride
Authors: De Kimpe Norbert , Verhé Roland , De Buyck Laurent , Schamp Niceas
Published: September 2010

Experimental evidence is provided that the rearrangement of N‐aryl α,α‐dichloroketimines with lithium aluminium hydride in ether, observed as a competitive reaction during the stereospecific synthesis of cis‐aziridines, proceeds via consecutive transformation of α‐chloroaziridines into azirinium chlorides and α‐imidoylcarbenium ions, the latter being trapped by chloride anion to afford β‐chloroenamines, which furnish rearranged anilines on treatment with lithium aluminium hydride.
Structure Cristalline du Diméthyle‐1,10 Dihydro‐2,7 Tétraphyllinate de Diéthylaminoéthyle
Authors: Dupont L. , Dideberg O. , Sarlet P.
Published: September 2010

The crystal structure of 1,10‐dimethyl‐2,7‐dihydro‐diethylaminoethyl tetraphyllinate (C29H43N3O4) was determined. The compound shows interesting pharmacological properties in the cardiovascular area. Space group is orthorhombic P212121, Z=4, a=11.448(4), b=21.810(5), c=11.052(4)Å. The molecule has a 2α‐H, 3α‐H, 7α‐H, 15α‐H, 19α‐CH, 20β‐H configuration.
Transformations Catalytiques Des Hydrocarbures Aromatiques. I. Étude Thermodynamique du Processus de Disproportionation du Toluène
Authors: Oprea S. , Azzouz A. , Dumitriu E. , Constantinescu M.
Published: September 2010

Toluene disproportionation based a chemical model by thermodynamic way was studied. The distribution of reaction products was calculated by computer (Felix C‐256). Disproportionation of toluene was also carried out using NaY zeolites as catalysts, where the cation was exchanged with La3+, Ce3+, Co2+, Sr2+ ions and the composition of reaction mixture was determinated by gas chromatography. A good agreement between the conversions calculated by thermodynamic way and experimental data was noticed proving that the discussed model can be applied.
Alkaloids From Catharanthus Roseus 1H NMR Study of 20′S‐Deoxyvinblastine and its N‐2′ Borane Complex
Authors: De Bruyn André , Sleeckx Jozef , De Jonghe J. P. , Hannart J.
Published: September 2010

The 1H NMR spectra of 20′ S‐deoxyvinblastine and its N‐2′ borane complex have been unraveled. 2D δ‐J‐resolved NMR allowed to measure the isolated peaks in the overlapping patterns of the amine borane complex. Both compounds can now easily be discriminated on basis of 1H NMR data.
Étude Structurale Des Stilbènes III. Structures Par Diffraction de Rayons X de Quatre Dérivés E ou Z de L'α, β‐Diphénylacrylate de Méthyle
Authors: Tinant B. , Touillaux R. , Declercq J. P. , van Meerssche M. , Leroy G. , Weiler J.
Published: September 2010

The X‐Ray structures of four methyl α, β‐diphenylacrylate derivatives were solved by direct methods from diffractometer data. (I) (Z)‐methyl β‐p‐nitrophenyl‐α‐phenylacrylate, C16H13NO4, is monoclinic, P21/n, with α=8.296 (1), b=6.703(2), c=24.863(5)Å, β=96.25(1)°, V=1374.4(5)Å3, Z=4, (II) (Z)‐methyl α‐p‐nitrophenyl‐β‐phenylacrylate, C16H13NO4, is triclinic, P1, with α=14.233(3), b=10.048(2), c=9.907(2)Å, α=80.75(1), β=92.98(1), γ=92.48(2)°, V=1395.6(5)Å3, Z=4. (III) (E)‐methyl β‐p‐nitrophenyl‐α‐phenylacrylate, C16H13NO4, is monoclinic, Cc, with α=5.819(2), b=16.610(5), c=14.843(4)Å, β=96.14(2)°, V=1426.4(7)Å3, Z=4. (IV) (E)‐methyl β‐methyl‐β‐p‐nitrophenyl‐α‐phenylacrylate, C17H15NO4, is monoclinic, P21/α, with α=13.751 (4), b=11.145(3), c=10.956(4)Å, β=116.42(2)°, V=1503.7(8)Å3, Z=4.

Molecular conformations are discussed and compared. The aromatic and ester substituents are generally twisted out of the ethylenic bond mean plane to avoid steric hindrance; only phenyl α in molecule II and ester group in III are coplanar with the CC bond. The C (arom.)‐CC bond angles are significantly greater than 120°.
Kinetics of N‐Formylation of Piperidine and Related Compounds
Authors: Maat L. , Peereboom M.
Published: September 2010

The kinetics of the N‐formylation of piperidine and 3‐methylpiperidine with chloral hydrate and 1,2,3,4‐tetrahydroisoquinoline with chloral in toluene, have been investigated. The reactions are first order in both reactants. The formylation of piperidine is faster than that of 1,2,3,4‐tetrahydroisoquinoline and somewhat slower than that of 3‐methylpiperidine.
Underpotential Adsorption of Mercury on Glassy Carbon
Authors: Kiekens P. , Van Broecke F. Den , Bogaert M. , Temmerman E.
Published: September 2010

The underpotential adsorption of mercury on glassy carbon has been studied. During electrodissolution, two stripping peaks are observed. The peak at more negative potentials corresponds to the oxidation of the bulk mercury, while the peak at more positive potentials results from the oxidation of mercury adsorbed on the surface of the electrode. The difference in peak potential between the adsorption (mono) layer peak and the bulk mercury peak has been related to the difference in work functions of deposit (mercury) and substrate (carbon).

Mercury monolayer formation is found to be favoured at more negative potentials where the oxide surface film is reduced provided that interfering ions are absent, such as H+ or Cu(II) that can be reduced simultaneously with the mercury ions.
Preparation and Conformational Study Of Cis‐5‐methyl‐N1,N4‐diacetyl‐2‐piperazine‐N′‐methyl‐carboxamide
Authors: Anteunis Marc J. O. , Hosten Noël G. C. , Borremans Frans A. M. , Tavernier Dirk K.
Published: September 2010

The preparation of the racemic title compound is reported. An extensive 1H and 13C nmr study reveals the presence of four rotameric states about the two amide bonds (Table 4) and discloses that all four isomers possess almost identical twist‐boat ring shapes characterized by an endocyclic torsion angle along the Cα‐Cβ and Cδ‐Cϵ bond of ‐35±5° if an L‐configuration is considered.
Addition Radicalaire du Propanal à Divers Alcènes et Cyclènes: Aspects Stériques et Polaires
Authors: Tabbaa I. , Cazaux M. , Lalande R.
Published: September 2010

Free radical addition of propanal to double bonds, initiated by benzoyl peroxide, mainly leads to two adducts, an aldehyde and a ketone, when the double bond has a methylene group; these results are explained in terms of polar effects in the free radical transfert reactions. When the double bond has no methylene group, only the ketonic adduct is obtained; the steric effects in the free radical addition step explain these results.
Catalytic Synergy in the Catalysis of N‐Ethyl Formamide Dehydration by Metal Oxides in Separate Phases
Authors: Ceckiewicz Stanislaw , Delmon Bernard
Published: September 2010

Mixtures of separately prepared oxides (of Mo, V, W, Bi, Sb, Sn) and BiPO4 exhibit a marked synergy in catalysis of the dehydration of N‐ethyl formamide in the presence of molecular oxygen, supporting the idea that a remote control of the active centres on one of the phases is exerted by the other phase via a special oxygen species.
Site Characterization on Reduced and on Sulfided Mo/Al2O3 Catalysis by Adsorption of Probe Molecules
Authors: Delgado E. , Fuentes G. A. , Hermann C. , Kunzmann G. , Knözinger H.
Published: September 2010

Carbon monoxide adsorption on reduced and on sulfided Mo/Al2O3 was studied by gravimetry and low temperature IR spectroscopy. It is suggested that Mo4+‐ CO and Mo2+‐CO adsorption complexes are formed on H2‐reduced and on sulfided catalysts, respectively. The saturation coverage by CO in the temperature range between 125 K and 200 K is considered to provide a reasonable estimate of the density of cus Mo sites.
Structure Resonance Theory. Correlations of Electron Affinities and Polarographic Reduction Potentials of Polycyclic Aromatic Hydrocarbons
Authors: Shawali Admad S. , Elanadouli Baghat E. , Párkányi Cyril , Herndon William C.
Published: September 2010

The electron affinities and the polarographic half‐wave reduction potentials of aromatic hydrocarbons were correlated with the logarithms of the structure counts of the neutral molecules and the radical anions, ln SC(R) and ln SC(R°), respectively. Regioselectivity in the electrochemical reduction of these hydrocarbons is also discussed. The results obtained in this work indicate that the structure resonance theory can be successfully used for correlations of this type, and that effects due to the delocalization of π‐electrons in both the neutral and charged species are important factors in the electro‐chemical reduction of aromatic hydrocarbons.
Diacylmethylencyclopropane Als Zwischenstufen Einer Cyclopropansubstitution An Aminocyclopropanen
Authors: Vilamder E.
Published: September 2010

The rapid formation and the stability of cylopropylidene iminius intermediates 2 allow an easy nucleophilic substitution in aminocyclopropane derivatives 1. It is shown that disaceptor‐substituted methylenecyclopropanes 4a, being isoelectronic with 2, may occur as intermediates in nucleophilic cyclopropane substitution, too. Aminocyclopropyl‐substituted CH‐acidic compounds 1a proved to be suitable starting materials for this new type of substitution. The synthesis of compounds 1a is described. The amino moisty in 1a can be replaced by several nucleophiles such as carbanions, hydride, cyanide oder alkoxide. The poor stability of the diacceptor‐substituted methylenecyclopropane intermediate 4a turned out to impose a limitation on the new type of nucleophilic cyclopropane substitution. Decomposition of 4a without added nucleophile is investigated in the thermolysis of the aminocyclopropane derivatives 1a. Thereby, either a Favorski‐type ring opening is caused or methylene dihydrofuranes are formed. The latter result from a diacylmethylene cyclopropane intermediate 4a. Methods for the structural assignment of the starting materials 1a and of the products 5a are discussed giving an information about the steric course of the nucleophilic substitution.
Fractal Dimension and Exclusion Volume in Microporous Solids
Authors: Fripiat J. J. , van Damme H.
Published: September 2010

Microporous solids have domains unavailable for molecules with radii(r) larger than the statistical radius (ro) of the throats spread within the porous space. In addition, according to recent concepts, their highly corrugated internal surface could be characterized by a fractal dimension D which contains the entire information about the shape of the surface. In this contribution, it is shown, that unexpectedly either the monolayer content obtained by using the B.E.T. equation, as well as the inclusion volume, is proportional to (r−D‐r−D) for any value 2 < D < 3, if ro is considered as a function of D. This conclusion is obtained by probing microporous solids (X zeolite, microporous silica and ammonium phosphomolybdate) with various molecules which have radii in the range 3.8 < r < 6.7 Å.
Equilibrium Geometry and Proton Affinity of Vinyl Ethers and Sulphides by Ab Initio Calculations
Authors: Ösapay K. , Delhalle J. , Hevesi L.
Published: September 2010

STO‐3G equilibrium geometries for methoxy ethene, 1–1‐dimethoxy ethene, their thio analogs as well as for the corresponding C‐protonated species are reported. The carbenium ion stabilizing abilities of methoxy and thiomethoxy groups are discussed in terms of calculated proton affinities.
The Zero Point of Charge of Cassiterite
Authors: Taha Fouad , El‐Roudi A. M. , Saleh M. B.
Published: September 2010

The zero point of charge (ZPC) of cassiterite was investigated by measuring the electrophoretic mobility, solution equilibrium, and flotation response as a function of solution pH. The ZPC was shown to lie at pH 2. The potential determining ions for cassiterite are H+ and OH−.

The effect of anionic and cationic collectors on the zeta potential of the mineral is studied. Mechanisms of charge development at the cassiterite ‐water interface are discussed. The preferential hydrolysis of surface ions or the adsorption, at the interface of the complexes formed in solution, appears to play an important part in establishing the surface charge.
Determination of Zirconium in Nodular Cast Iron by Instrumental Proton Activation Analysis
Authors: Goethals P. , Bosman B. , Vandecasteele C.
Published: September 2010

An instrumental method for the determination of zirconium in nodular cast iron using the 90Zr(p,n) 90Nb reaction was developed. The 2319 keV γ‐rays of 90Nb (t1/2=14.6 h) were measured with a Ge(Li) detector with 4 cm of lead interposed between the sample and the detector.

For concentrations ranging from 200 to 1200 μg.g−1, the experimental standard deviation ranges from 2 to 5%. The results are in good agreement with those obtained by ICP‐emission spectrometry and were used to establish a linear calibration graph for the determination of zirconium in cast iron by X‐ray fluorescence spectrometry (XRF) on the Zr Kα line.
Gnetins in Welwitschia
Authors: Lins Arlete P. , Yoshida Massayoshi , Gottlieb Otto R. , Gottlieb Hugo E. , Kubitzki Klaus
Published: September 2010

A wood sample of Welwitschia mirabilis is reported to contain nerolidol and para‐hydroxybenzaldehyde, besides two dehydroresveratrol dimers gnetins F and G and two dehydroresveratrol trimers gnetins H and I for which structures are proposed. Other oxidative resveratrol oligomers, gnetins A, B, C, D and E, have been isolated previously from three Amazonian Gnetum species. These facts provide welcome evidence for the discussion of relationships within the Gnetatae.
Asymmetric Synthesis of Isoquinoline Alkaloids: (R)‐ and (S)‐2‐Ethoxycarbonyl‐1‐Formyl‐6, 7‐Dimethoxy‐1,2,3,4‐Tetrahydroisoquinoline as Versatile Precursors
Authors: Czarnocki Zbigniew , Maclean David B. , Szarek Walter A.
Published: September 2010

A method is described for the preparation of (R)‐ and (S)‐2‐ethoxycarbonyl‐1‐formyl‐6,7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline involving a Swerntype oxidation of (R)‐ and (S)‐2‐ethoxycarbonyl‐1‐hydroxymethyl‐6, 7‐dimethoxy‐1,2,3,4‐tetrahydroisoquinoline {(R)‐ and (S)‐2‐(ethoxycarbonyl)calycotomine}. The utility of these aldehydes in asymmetric synthesis of isoquinoline alkaloids has been demonstrated by their conversion into (S)‐ and (R)‐xylopinine, respectively; also, the (R)‐aldehyde has been employed for the synthesis of (8S,14S)‐coralydine.
Formation of Pyrazoles and of Imidazoles from Phenacyl Ketal Hydrazones of Aldehydes
Authors: Scarpetti† David , Kano†† Kunio , Anselme Jean‐Pierre
Published: September 2010

The cyclization of phenacyl ethylene ketal (pek) hydrazones of glyoxals, benzaldehyde and acetaldehyde to the pyrazoles is described; in the case of the hydrazones of benzaldehyde and acetaldehyde, the corresponding imidazoles are also formed. A mechanism is suggested for the formation of the imidazoles.
Infrared study of the Proton Acceptor Ability of Nicotine
Authors: De Taeye J. , Zeegers‐Huyskens Th.
Published: September 2010

The interaction between nicotine and phenol derivatives has been studied by infrared spectrometry in solvents of low polarity. The enthalpies of complex formation ranged from 24 to 36 kJmol−1 and the ΔvOH values from 440 to 580 cm−1, indicating a rather strong interaction. The FT‐Infrared spectra (1100‐600 cm−1) strongly suggest that the interaction occurs at the N atom of the pyridine ring showing that hydrogen bond formation is governed by the accessibility of the lone pair of the base.
Spectroscopic Study of the PD(II) Complexes with 2 Amino‐4,6 Dimethylpyrimidine
Authors: Kovala‐Demertzi D. , Tsangaris J. M. , Desseyn H. O. , van Der Veken B. J.
Published: September 2010

Complexes of Pd(II) with 2 amino‐4,6 dimethylpyrimidine have been studied employing elemental analysis, thermal analysis, U. V.‐Vis, infrared and Raman techniques. The complexes have been isolated at PdL2Cl2(A). Pd2L3Cl4(B). PdCl2.3H2O(C) and Pd2L2Br3.3H2O(D). The metal is bound to the ligand through the nitrogen atom of the pyrimidine ring system while the amino group is not involved in the complex formation.
Deoxygenation, Deaeration and Degassing: A Survey and Evaluation of Methods
Authors: Luyckx Geert , Ceulemans Jan
Published: September 2010

Techniques for the removal of dissolved gases from liquids are reviewed and classified according to their working principles. Consideration of these working principles reveals some inherent limitations of certain techniques and it may be concluded that the different methods complement each other in a number of aspects. Proton spin‐lattice relaxation time measurements and polarographic analyses are used for evaluation of different deoxygenation methods. It is concluded that for most purposes the different methods yield satisfactory results if applied properly and within the inherent limitations of the techniques. When the presence of oxygen is very critical and its concentration must be reduced to very small amounts, a combination of methods appears advisable.
Pyrolyse‐Éclair Sous Vide de 1,2,4‐Triazolides = Une Étude par Spectrométrie de Masse en Tandem
Authors: Maquestiau A. , Puk E. , Flammang R.
Published: September 2010

A real‐time analysis of the flash‐vacuum pyrolysis products of some 1,2,4‐triazolides has been performed by tandem mass spectrometry. Beside decay products, ketenes and the parent 1,2,4‐triazole, 1‐acyltriazoles give rise to 5‐alkyloxazoles and nitrogen. This ring transformation reaction implies a sigmatropic shift of the acyl group from nitrogen to carbon, loss of nitrogen and cyclisation of the biradical intermediate. 5‐aryloxazoles are similarly obtained from 1‐aroyltriazoles.
Synthèse des Benzimidazolyl‐2 Méthyl‐5′ Pyrazolyl‐3′ Méthanes a Partir des Acétylméthylène‐4 Benzodiazepine‐1,5 Ones‐2
Authors: Essassi E. M. , Elabbassi M. , Fifani J.
Published: September 2010

Hydrazionolysis of 4‐acetylmethylene‐1,5‐benzodiazepin‐2‐ones 1, 2 gives, depending on the experimental conditions, either N‐(2‐aminophenyl) 5′‐methyl‐3′‐pyrazolyl acetamides 3‐4 or 2‐benzimidazolyl‐5′‐methyl‐3′‐pyrazolylmethanes 5‐6.
I‐Isocyanoaromadendrane, A New Isonitrile Sesquiterpene from the Sponge Acanthella Acuta
Authors: Braekman J. C. , Daloze D. , Deneubourg F. , Huysecom J. , Vandevyver G.
Published: September 2010

Two isonitrile sesquiterpenes 2 and 3 have been isolated from the toxic dichloromethane extract of the marine sponge Acanthella acuta. Compound 2 was found to be identical with axisonitrile‐3. compound 3, 1‐isocyanoaromadendrane, is a novel sesquiterpene whose structure has been determined on the basis of its spectral properties and by chemical correlation with palustrol.
Mechanism of the Catalytic Reduction of Hydroperoxides by Ebselen : A Selenium ‐ 77 Nmr Study
Authors: Fischer Hartmut , Dereu Norbert
Published: September 2010

Ebselen (2‐phenyl‐1,2‐benzisoselenazol‐3(2H)‐one 1, a non‐toxic selenium containing heterocyclic compound has been shown to display both anti‐ inflammatory activity in vivo and GSH‐Px‐like activity in vitro. Using 1H and 77Se NMR we investigated the mechanism of reduction of hydroperoxides by thiols in the presence of 1. A catalytic cycle depending on the formation of diselenides and selenenylsulfides was found. The selenenic acid oxidation level present in compound 1 is particularly stable because of the intramolecular cyclisation. This contrasts with previously reported results concerning the oxidation of organoselenium compounds.
Comparative Hydrodesulfurization of Athabasca Oil Sands Coker Gas Oil Over Ni‐Mo and Co‐Mo Catalysts
Authors: George Zacharia Mathew , Mohammed Peter
Published: September 2010

The hydrodesulfurization of Athabasca oil sands coker gas oil has been compared over Ni‐Mo and Co‐Mo catalysts on the basis of rate constants at 400°C, 10.3 MPa (H2) and at an LHSV of 12.0 h−1. Both catalysts were cylindrical extrudates of 3.5 mm × 1.6 mm. A Berty Continuous Stirred Tank Reactor (CSTR) was used for the hydroprocessing. Although the Ni‐Mo catalyst had higher activity per gram of catalyst, on the basis of the rate constant per gram of molybdenum, the Co‐Mo catalyst was slightly more active with lower activation energy than the Ni‐Mo catalyst for HDS.
NMR studies on imidines. VII. The tautomerism of mono‐n‐aryl substituted phthalic imidines. A 1H and 13C nuclear magnetic resonance study
Authors: Spiessens Luc I. , Anteunis M. J. O.
Published: September 2010

1H and 13C NMR data indicate the presence of N‐aryl substituted phthalic imidines to exist as 3‐amino‐1‐N‐arylimino‐1H‐isoindole compounds in DMSO‐d6. In CDCl3 a tautomeric equilibrium mixture containing 20% of the imino form is observed. The presence of a dimeric association through intramolecular H bonds is suggested.

It is shown that intramolecular NH‐N hydrogen bonds displace the tautomeric equilibrium toward the imino tautomer in 2‐pyridyl substituted phthalic imidines. In the reaction product of phthalic imidine and 2, 6‐diaminopyridine, 11, two pairs of intramolecular NH‐N hydrogen bonds result in the presence of both amino and imino tautomeric forms in the same molecular species.
Azadiene derivatives as synthetic intermediates
Authors: Barluenga José
Published: September 2010

The applicability of 4‐amino‐1‐azabutadienes 1 in synthesis of five‐, six‐, and eight‐membered ring heterocycles is demonstrated; several open‐chain compounds have also been diastereo‐ or enantio‐selectively prepared. The synthesis and reactivity of both neutral and electron‐poor 2‐azabutadienes 2 is presented; these heterodienes rapidly react, in a (4+2)‐fashion, with several dienophiles to form the corresponding cycloadducts. The synthesis of the 2‐aminosubstituted 1,3‐butadienes 3 and their ability to act as dienes in Diels‐Alder reactions has also been explored; the behaviour of 3 as enamine is shown, as well.
L'Évaluation Semi‐Empirique des Densités de Spin π dans les Radicaux Carbones
Authors: Leroy Georges , Peeters D. , Sana M. , Wilante C.
Published: September 2010

A critical analysis of the well known McConnell relations a = Qρ π s(Cα) leads us to propose a new value for the parameter Qβ and an additive rule to calculate the πspin densities, ρ πs(Cα). Other values of substituent parameters ΔXi are also proposed. The difference between a(Hβ)/Qβ and the π spin densities calculated by use of the additive relation is generally negative, in captodative‐substituted ethyl radicals. Furtheron, it is found that the observed values of ρπs(Cα) are pretty well correlated to the corresponding thermodynamic stabilization energies, in the case of cd‐substituted radicals.