bluuebunny/crossref_metadata_2025 huggingface dataset:
Extraction and Spectrophotometric Determination of Palladium(II) with N‐P‐Chlorophenylbenzohydroxamic Acid
Authors: Agrawal Y. K. , Chudasma S. P.
Published: September 2010

A rapid extraction and spectrophotometric determination of palladium with N‐p‐chlorophenylbenzohydroxamic acid (N‐p‐Cl‐BHA) is described. The palladium forms an orange coloured complex with N‐p‐Cl‐BHA at pH 3.0. It is extracted with chlorobenzene and has a maximum absorbance at 430 nm. Its molar absorption coefficient is 7.0×102 1 mol−1 cm−1. The sensitivity of the Pd‐p‐Cl‐BHA complex is enhanced by the addition of dithizone and has a maximum absorbance at 520 nm with a molar absorption coefficient of 3.0×103 1 mol−1 cm−1. The effects of pH, solvents, reagent concentration and diverse ions are studied.
Extraction and Spectrophotometric Determination of Zirconium with N‐P‐Chlorophenylbenzohydroxamic Acid and Morin
Authors: Agrawal Y. K. , Patel S. A.
Published: September 2010

A spectrophotometric and a fluorimetric method for the determination of zirconium with N‐p‐chlorophenylbenzohydroxamic acid and morin have been developed. The procedure is based on the extraction of zirconium with N‐p‐Cl‐BHA into iso‐amyl alcohol from 0.2‐0.5 N H2SO4 and then forming its complex with morin. The greenish yellow complex has a maximum absorbance at 420 nm with a molar absorptivity 3.5×104 1 mol−1 cm−1 and gives the fluorescence. The intensity of the Zr‐p‐Cl‐BHA‐morin complex can be enhanced by the addition of ammonium carbonate and the molar absorptivity becomes 1.3×105 1 mol−1 cm−1 at 410 nm.
Subcellular Distribution of α‐D‐Mannosidase Activity in Cultured L1210 Cells
Authors: Zenebergh A. , Trouet A.
Published: September 2010

Three types of α‐D‐mannosidase have been found in L1210 cells, a lysosomal one with an optimum activity at pH 4; a soluble one, thermosensitive, with an optimum activity at pH 6, and one with an optimum activity at pH 5.25, probably related to the Golgi apparatus.
The Chemistry of 2H‐3, 1‐Benzoxazine‐2, 4(1H)‐Dione: Reactions with 4h‐furo[3,4‐d][1,3] Oxazine‐2(1h), 4‐Dione
Authors: Olagbemiro Timothy Oyebode
Published: September 2010

The novel tetracyclic ring system represented by 4 and 5 has been developed by the reactions of isatoic anhydride 1a with 3‐isocyanato‐4‐furoyl chloride 3b and by the reaction of 4H‐furo[3,4‐d][1,3] oxazine‐2(1H), 4‐dione 3a with 2‐isocyanatobenzoyl chloride 1b, respectively. The synthesis as well as the mechanism of the reaction are briefly discussed.
Comparative Study of Enthalpies of Hydrogen Bond Formation of Enamino and Amino Ketones
Authors: van Brabant‐Govaerts H. , Huyskens P.
Published: September 2010

The complexation enthalpies ‐ΔHab and the stability constants Kab of complexes between 3‐dimethylamino‐1‐phenyl‐2‐propene‐1‐one and some nine pnenols of increasing acidic strengths were determined in benzene at 298.16 K and compared with the values characteristic of the corresponding base without double CC bond (β‐dimethylaminopropiophenone). The complexation enthalpy ‐ΔHab with a given phenol is systematically lower for the unsaturated base, the differences being of the order of 6 to 10 kJmole−1. The complexation enthalpy of the saturated base with a given phenol is of the order of magnitude of that found for the imidazoles and for the tertiary alkylamines. For the unsaturated base however, the values ressemble these found for the ketones and for the amides. This suggests that contrarily to the saturated base where the complexation involves the nitrogen atom, hydrogen bond formation by the unsaturated compound mainly takes place on the carbonyl group. The complexation enthalpy ‐ΔHab increases for both bases with the pKa of the phenol. From a comparison with similar relations for the amides a value of ‐1.9 for the pKa in water of the unsaturated base is found. The experimental value in acetic acid anhydride is ‐1.0. Applying the same method a value of ‐4.0 is estimated for the pKa of acetone and of ‐5.8 for acetophenone. The standard entropy change −ΔS0ab varies linearly with ‐ΔHab for both compounds but the straight line is shifted downwards from about 10 JK−1mole−1 for the unsaturated base. This is partly due to the presence of two lone pairs of electrons on the carbonyl group.
Een Nomogram‐Weergave Van Concentratie‐Effecten in Verdunde Polymeeroplossingen
Authors: Peeters F. A. H.
Published: September 2010

The influence of the concentration c on quantities, such as the coefficient of sedimentation and the c‐reduced specific viscosity or osmotic pressure, can be depicted in a nomogram by a curve, characteristic for the homologous, diluted polymer/solvent system. Measured at a single concentration, their values for c=0 can be derived from the nomogram.
Solution Conformation of Calcium‐Ionomycin
Authors: Anteunis Marc J. O. , Verhegge George
Published: September 2010

The solution conformation of Ca2+‐ionomycin in CDCl3 has been revealed by 1H nmr spectroscopy to be almost identical with that observed2 in the crystal. Only minor differences (e.g. the conformational state of the penultimate ring) were observed. The completeness of the screening for the ion from the membranic bilayer surrounding is therefore also best explained2 by a bimolecular aggregation of the ionophore. It is concluded that the cationic transport will be mainly governed by entropy contributions, as neither the flexible architecture nor the dimension of the aggregate will account for large enthalpy changes during capture and during the transfer along the lipophilic trajectory.
A preliminary investigation of the sorption of hydrogen at high pressure by MoS2
Authors: Sampson C. , Thomas J. M. , Vasudevan S. , Wright C. J.
Published: September 2010

Hydrogen is sorbed by “amorphous” molybdenum sulphide at two sites. One site becomes saturated at pressures less than 1 atmosphere and at temperatures less than 423 K. This is the site at which linear S‐H bonds form. The second site is occupied at higher temperatures, and the preliminary data suggests saturation is reached at ∼ 50 Atm.
On the Role of Promoter Atoms in Unsupported Hydrodesulfurization Catalysts: Influence of Preparation Methods
Authors: Candia Roberto , Clausen Bjerne S. , Topsøe Henrik
Published: September 2010

Unsupported Co‐Mo catalysts were prepared by two different methods:by the co‐maceration (CM) method and by a new homogeneous sulfide precipitation (HSP) method. Structural examinations by means of XRD and Mössbauer Emission Spectroscopy (HES) show that the CM catalysts contain several phases with Co9S8 being the dominant cobalt containing phase. On the other hand, the HSP catalysts are shown to contain only one CO phase within an extended range of Co/Mo atomic ratios and this phase is the Co‐Mo‐S phase. Like in the case of supported catalysts, the Co‐Mo‐S phase is shown to be the phase responsible for the activity, whereas Co9S8 is shown to have little or no influence on the activity. The differences in activity observed between the HSP and CM catalysts as well as other unsupported catalysts studied in the literature all seem to be related to differences in the preparation procedures resulting in different promotional efficiencies for the formation of Co‐Mo‐S.
Coordination Compounds of Heterocyclic and Derivatives I‐ Synthesis AZO Characterization of Bivalent Metal Chelates with Some Imidazole AZO Dyes
Authors: Mahmoud M. R. , Abd El‐Hamide R. , Wahab A. A. Abdel , Salman H. M.
Published: September 2010

2‐(4‐R‐Phenylazo)‐4,5‐diphenylimidazole (R=H, PAI; = OH, HPAI; = COOH, CPAI) acts as a bidentate chelating ligand to form stable complexes with Co(II), Ni(II), Cu(II), Zn(II), Cd(II) and Hg(II) ions. It is concluded that the ligands are bonded to the metal ion through the α‐nitrogen atom of the aryl azo group and N‐3 of the imidazole ring. The apparent formation constants of the complexes in solution have been determined.
The Crystal Structure of 2,4‐dioxa‐3‐oxo‐3‐Phospha‐3‐Phenoxy‐trans‐Bicyclo[4.4.0]decane, A Cyclic Phosphate with an Axial P = 0
Authors: van Nuffel P. , Lenstra A. T. H. , Geise H. J.
Published: September 2010

The isomer of 2,4‐dioxa‐3‐oxo‐3‐phospha‐3‐phenoxy‐trans‐bicyclo [4.4.0] decane with the configuration P3(S), C1(S), C6(R) or its mirror image crystallizes in the space group P21/n with Z = 8, a = 20.59, b = 6.587, c = 20.67 Å, β = 114.9°. The molecule has an all chair form with P = 0 pointing into axial and P‐OR into equatorial direction. It is the first X‐ray determination of a cyclic phosphate with an axial P = 0.

Systematic geometrical differences in comparison with cyclic phosphates having an equatorial P = 0 are discussed. They are found to be in complete agreement with predictions based on the anomeric effect.
Structure de la N‐Acetyl‐L‐Thiazolidinemethylcarboxamide‐4 C7H12N2O2S
Authors: Tinant Bernard , Declercq Jean‐Paul , Germain Gabriel , van Meerssche Maurice
Published: September 2010

The crystal and molecular structure of N‐acetyl‐L‐thiazolidine‐4‐methyl‐carboxamide has been determined by three dimensional X‐ray diffraction analysis. The thiazolidine ring conformation is compared with these of N‐acetyl‐L‐thiazolidine‐4‐carboxylic acid and N‐acetyl‐L‐thiazolidine‐4‐carboxamide.

Crystal data are as follow: hexagonal, P65, a = b = 8.785 (4), c = 20.773 (4) Å, V = 1388.4 Å3, Mr = 188.25, Dx = 1.35 Mg m−3 for Z = 6.
Alkaloids from Catharanthus Roseus. Isolation and Identification of 17‐Desacetoxyvinblastine and 17‐Desacetoxyleurosine
Authors: De Bruyn André , De Taeye Leo , Simonds Ronald , Verzele Maurice , De Pauw Christiaan
Published: September 2010

17‐desacetoxyvinblastine and 17‐desacetoxyleurosine have been isolated from Catharanthus roseus. The latter has not been recognized so far in this plant. The 1H NMR and mass spectrometry data confirming the proposed structures are presented.
Solubilité des Oxydes de Cobalt(II), de Cuivre(I), de Cuivre(II), de Nickel(II) et du Bromure de Tétraméthylammonium dans les Solvants mixtes EAU‐DMSO, à 25°C
Authors: Richard J. M. , Sabiani N. , Zahra C.
Published: September 2010

In the mixed solvent water‐DMSO, at 25°C, the solubility of Co(II), Cu(I), Cu(II) and Ni(II) oxides have been determined by atomic absorption spectroscopy and the solubility of tétraméthylammonium bromide by potentiometry.
The role of Dimethylsulphoxide as a Solvent in the Kinetics of the Acid and Alkaline Hydrolyses of Benzyl Acetate
Authors: Khalil Fayez Y. , Hanna M. T.
Published: September 2010

The rate of the acid‐catalysed hydrolysis of benzyl acetate in DMSO‐water mixtures increases slightly first then decreases with increase of DMSO content of the medium in a normal manner. However, the rate of the base‐catalysed reaction in the same solvent system increases with addition of DMSO. This behaviour was attributed to the ability of the DMSO molecules to desolvate hydroxide anions through formation of 1:2 association complexes with water molecules. A kinetic equation involving the simultaneous direct as well as inverse proportionality of the rate to the water concentration was explained. The effects of the dielectric constant and solvation changes on the rate constant and thermodynamic parameters were discussed.
Hydrogenation of α, β‐Unsaturated Aldehydes and Ketones on New AlPO4‐Supported Nickel Catalysts
Authors: Campelo J. M. , Garcia A. , Luna D. , Marinas J. M.
Published: September 2010

The liquid phase catalytic hydrogenation of Acrolein (A) and Methyl‐vinylketone (MVK) were studied over a series of new nickel catalysts supported on AlPO4, and AlPO4‐Al2O3 and AlPO4‐SiO2 systems, in methanol as solvent, at initial hydrogen pressure of 4.1 bar and temperatures between 298‐323 K. The hydrogenation of the C‐C double bond, yielding propanal or butanone were obtained in a first step at a yield of 100% because the reduction of butanone was not possible and, in the acrolein hydrogenation a kinetically consecutive process, acrolein → propanal → 1‐propanol, was obtained and 1‐propanol appeared just after acrolein was finished.

The C‐C double bond of acrolein was hydrogenated more slowly than it was in methyl‐vinyl‐ketone. This result is probably due to an electronic effect of substitution from the methyl group. Moreover, the catalytic activity varies markedly with the support and was found to diminish as the nickel content decreased. The order of decreasing activity for the C‐C double bond: Ni/AlPO4‐SiO2 > Ni/AlPO4 > Ni/AlPO4‐Al2O3 is valid for the hydrogenation of both substrates and it is associated with an effect of metal‐support interaction.
Isomérisation des Ions Avant Leur Fragmentation en Spectrométrie de masse: Transfert de Groupes Phényles dans les Epoxydes, Aldéhydes et Cétones Protones
Authors: Audier H. E. , Milliet A. , Bouchoux G. , Denhez J. P.
Published: September 2010

MIKE spectra of protonated, substituted phenylacetophenones, show that their fragmentations occur after the interconversion of phenyl groups.
1,2,3‐Triazolo(1,5)Azines et Autres Hétérocycles Azotés Dérivés D'Azine‐carboxaldéhydes
Authors: Maury Georges , Meziane Driss , Sraïri Driss , Paugan Jean‐Paul , Paugam Renée
Published: September 2010

α‐(N)‐azine‐carboxaldehydes are convenient precursors of 1,2,3‐triazolo (1,5) azines. Through oxidative cyclization of the corresponding hydrazones we have prepared the new 1,2,3‐triazolo (1,5‐b)pyridazine and 1,2,3‐triazolo (1,5‐a)pyrazine. Unlike the other azaindolizines these compounds are degraded by electrophiles. Attempts to prepare imidazo(1,5‐c) pyrimidine or derivatives have been carried out either from 4‐aminomethylpyrimidine or from ethyl 2‐(4‐pyrimidinyl)propionate.
The Crystal Structure of 2‐Hydroxyiminomethyl‐4′‐Carbamoyl‐1, 1′‐oxybis(Methylene)Dipyridinium Dichloride Monohydrate (HI‐6) (laq.)
Authors: van Havere W. , Lenstra A. T. H. , Geise H. J. , van Den Berg G. R. , Benschop H. P.
Published: September 2010

C14H18Cl2N4O4 is monoclinic, P21/n with Z = 4, a = 13.347(4), b = 8.988(5), c = 15.191(6)Å and β = 106.14(4)°. RW = 0.0829 for 2018 reflections.

The title compound, reactivating phosphylated acetylcholinesterase, is considered for use as antidote against intoxication with certain organophosphates, primarily the nerve agent soman. It has the E‐configuration at the oxime moiety. The possibility of Π‐localization in one pyridinium ring is discussed.
Alcoolyse de L'Epichlorhydrine du Glycerol sur Catalyseur Solide Synthèse Commode D'éthers du Chloro‐3 Propane Diol‐1, 2
Authors: Thuy Vu Moc , Petit Huguette , Maitte Pierre
Published: September 2010

Monoethers of 3‐chloro‐1, 2 propanediol were easily obtained in good yields from epichlorohydrin and alcohols under catalysis of actived montmorillonite K 10.
Structure de Triterpenoides Nouveaux Isoles de Atroxima Afzeliana
Authors: Warin Babady‐Bila R. , Delaude C. , Huls R.
Published: September 2010

The roots bark saponin of Atroxima afzeliana yields on hydrolysis three new triterpenoids: atroxigenic acid, atroxigenin and atroxigenic acid lactone.
Microcomputers and Organic Synthesis
Authors: Barone R. , Chanon M. , Cadiot P. , Cense J. M.
Published: September 2010

The first microcomputer program in the field of computer assisted organic synthesis is described. It is written in BASIC and runs on an Apple II micro‐computer.
Structure de Complexes du Cuivre(I) Avec la Thiourée: II. ‐ Sulfate D'Hexakis (Thiourée)‐Dicuivre (I) Monohydrate Cu2 [SC (NH2) 2] 6SO4. H2O
Authors: van Meerssche M. , Kamara R. , Declercq J. P. , Germain G.
Published: September 2010

The title compound is a new Cu(I)‐thiourea complex containing binuclear cyclic cations (Cu2tu6)2+ wich, contrary to other similar knew compounds, exhibits a non‐centrosymmetrical configuration. Crystal data are as follow: orthorhombic, Pbca, a = 19.251(7), b = 12.309(2), c = 21.484(5)Å, Dx = 1.82 Mg m−3 for Z = 8.
IR Study on the Solid State Reaction between Iron Hydroxide and KCN
Authors: Hoste S. , Verdonck L. , van Der Kelen G. P.
Published: September 2010

Freshly prepared hydrated ferric oxides easily decompose, even at room temperature. The ESCA O is spectrum of goethite, heated inside the spectrometer at different temperatures, however, shows that thermal transformation of goethite to hematite only starts around 200°C. In an attempt to estimate the relative amounts of ferrihydrite and goethite in artificial mixtures of the synthetic pure compounds by IR spectroscopy the use of KCN as an internal standard was tested. It was noted however that a selective solid state reduction, of the Fe(III)‐ions in the amorphous fraction to Pe(II)‐cyano complexes occurs during the preparation of the samples for analysis. A rough correlation is found between the fraction of oxalate soluble Fe in different mixtures and the ratio of the peak intensities of the CEN stretching vibrations in free KCN (2080 cm−1) and the Fe(II)‐pentacyano‐aquo complex (2044 cm−1).
Études Structurales en Relation Avec le Concept de Substitution “Capto‐Dative” I. Structures aux Rayons X du Bis(Éthylthio)‐2, 3 Diphényl‐2, 3 Butanedinitrile‐1, 4 C20H20N2S2 et du bis (Éthylthio)‐2, 3 BIS (p‐Tolyl)‐2, 3 Butanedinitrile‐1, 4 C22H24N2S2
Authors: Tinant B. , Arte E. , Parfonry A. , Declercq J. P. , Germain G. , van Meerssche M.
Published: September 2010

The crystal structures of the title compounds have been determined using X‐Ray diffractometry in order to study the effects of capto‐dative substitution on molecular geometry. The carbon‐carbon central bond is significantly stretched. 2, 3‐Bis (ethylthio) ‐2, 3‐diphenyl‐1, 4‐butanedinitrile (compound A) is triclinic, P1, with a = 15.703 (9), b = 14. 902(5), c = 8.655(4)Å, δ = 97.52(3), β = 89.87(4)°, γ = 75.59(4)°, V = 1943.3 Å3, Z = 4 and Dx = 1.20 Mg m−3. 2, 3‐Bis (ethylthio)‐2, 3‐bis (p‐tolyl)‐1, 4‐butanedinitrile (compound B) is monoclinic, P2/n with a = 16‐872(8), b = 12, O82(5), c = 10.329(5)Å, β = 94.16(4)°, V = 2100.0 Å3, Z = 4 and Dx = 1.21 Mg m−3.
Contribution to the Theoretical Study of the Onno Dimer
Authors: Sana Michel , Leroy Georges
Published: September 2010

In this work we study the geometry, the vibrational properties including the IR‐absorptions and the thermodynamical properties of the NO radical dimers containing a central NN bond. An ab initio‐SCF potential energy surface is built up at the 6‐31G level. We find two equilibrium structures: the most stable having a trans conformation. The cis form is less stable with respect to the first by 2 kcal mol−1. Two transition structures separate the minimum energy points: the first respectively low in energy corresponds to a perpendicular arrangement and the second higher in energy has a linear structure. The predicted IR spectra, as well as the heat of formation of the dimers, are somewhat different from the experimental data. It seems that the exact nature of the experimentally observed dimer remains an open question.
Biomolecules Bearing the SAsMe2 Group: Nucleoside Derivatives
Authors: Dereu Norbert L. M. , Zingaro Ralph A.
Published: September 2010

A number of compounds of the type GS‐ and GSeAsR2, where G is a monosaccharide, a thio amino acid, a thiol‐containing di‐ or tripeptide or cholesterol display carcinostatic activity in in vivo mouse test systems.

The synthesis and characterization of derivatives in which G is a nucleoside and the synthesis of an arsenic‐containing precursor of 5‐thioglucose are described. Of the nucleoside derivatives thus far screened, none displays carcinostatic activity.
Taft Four Parameter Equation as a Mechanistic Tool in Chromic Acid Oxidation of Aliphatic Esters
Authors: Musala Reddy P. , Jagannadham V. , Sethuram B. , Navaneeth Rao T.
Published: September 2010

The utility and applicability of Taft four parameter equation in the chromic acid oxidation of acetate esters of methanol, ethanol, i‐propanol, n‐propanol, i‐butanol and n‐butanol in 20% aqueous acetic acid and 3.OM H2SO4.
Anomalies dans L'esterification D'acides Éthyléniques par la Méthode AU N,N′‐Carbonyldiimidazole
Authors: Montaudon E. , Campagnole M. , Bourgeois M. J. , Maillard B.
Published: September 2010

The reaction of N,N′‐carbonyldiimidazole with but‐3 enoic acid did not lead to the expected azolide; its rearrangement into conjugated isomer was followed by imidazole addition to the double bond. These two reactions make inefficient this preparative method for esters and peresters of alkyl substituted α, β‐ethylenic acids and β,γ‐ethylenic acids without substituent on the α‐carbon.
Crystal Structure of 3‐Phenyl‐4‐Tosylimino‐1,3‐Thiazetidine‐2‐One
Authors: King Geoffrey S. D. , van Meervelt Luc , L'abbé Gerrit
Published: September 2010

Studies on the chemistry of 3‐phenyl‐4‐tosylimino‐1,3‐thiazetidine‐2‐one (4) have shown that the molecule can be attacked by nucleophiles at both the electrophilic centres C2 and C4 of the ring system.1 This interesting aspect prompted us to determine its crystal structure for comparison with those of compounds 1‐3.2
NMR Studies on Imidines. II. 1H AND13 C Nuclear Magnetic Resonance Study on The Tautomerism and Geometrical Isomerism of 3‐Aryliminoisoindolinones
Authors: Spiessens Luc I. , Anteunis Marc J. O.
Published: September 2010

3‐Aryliminoisoindolinones 2. [Ar = phenyl, p‐tolyl, 2′‐pyridyl, 2′‐amino‐6′‐pyridyl, 3′‐ pyridyl; and 2,6‐bis(1‐oxo‐3‐isoindolinylidene)aminopyridine (2f)I have been fully examined by 1H and 13C NMR spectroscopy. A complete analysis of 13C‐ 1H coupling constants is given for three of the compounds (2c, 3a, 4b). Only the arylimino tautomeric forms are present in polar (DMSO‐d6; CD3OD) and apolar solvents (CDCl3) as established by comparison of 1H and 13C NMR chemical shift values of 2 with those of suitable model compounds (3, 4, 6 and 7). It is shown that both the endo‐ and exocyclic N‐methylated aryliminoisoindol(en)inones (3 and 4) adopt the E configuration (due to steric hindrance of the N‐methyl group) but that the title compounds are present in solution as 4:1 mixtures of Z and E components (Figure 4). This is not the case for the 2′‐pyridyl derivatives (2c, 2e, 2f) where the Z form benefits from an intramolecular hydrogen bond.

An interesting proximity 13C chemical shift effect is produced by the variation in steric crowding in the E vs Z isomers of the title compounds.
High Yield Synthesis of Filicinic Acid Based on the Polychlorination of 4,4‐Dimethyl‐2‐Cyclohexenone. Part I: One‐pot Synthesis of 2,3,5,6‐Tetrachloro‐4,4‐Dimethyl‐2,5‐Cyclohexadienone
Authors: De Buyck Laurent , Verhé Roland , De Kimpe Norbert , Schamp Niceas
Published: September 2010

2, 3, 5, 6‐Tetrachloro‐4,4‐dimethyl‐2,5‐cyclohexadienone (4), a useful precursor for synthetic filicinic acid (5). was prepared in 88‐94% yield by poly‐chlorination of 4,4‐dimethyl‐2‐cyclohexenone (1) or 4,4‐dimethylcyclohexanone (11) with chlorine in dimethylformamide under dehydrochlorinating conditions. Introduction of the fourth chlorine atom required a medium saturated with hydrogen chloride and an optimal temperature in the range of 40‐70°C. This is in accord with chlorination of the enol resulting from Michael addition of hydrogen chloride to the trichlorodienone 3, followed by dehydrochlorination. Besides the one‐pot procedure for 4, stepwise methods provided several intermediates in high yields.
Complexes of Bis(stannyl)Methanes, ‐Propanes and ‐Butanes with Hexamethylphosphoric Triamide
Authors: Jurkschat Klaus , Gielen Marcel
Published: September 2010

Kuivila (1) has shown that bis(dichloromethylstannyl)methane forms a complex with two bridging molecules of dimethylsulfoxide whereas (chlorodimethylstannyl)(dichloromethylstannyl)methane gives a one‐to‐one complex also with a bridging Me2SO oxygen atom. This paper prompt us to disclose some results concerning the complexes of bis(halodiphenylstannyl)methanes, 1, and of 1,3‐bis(chlorodiphenylstannyl)propane, 2, (2) with hexamethylphosphoric triamide (HMPA), viz 3≡1,: HMPA, and 4≡2:2 HMPA (2).
A Conformational Analysis of 2‐(X), 4‐(Y)‐Substituted Pentanes (X, Y = OH, SH), Using Chiroptical Properties and1H NMR Spectroscopy
Authors: Spiessens L. I. , Becu C. , Hosten N. , Anteunis‐De Ketelaere F. , Anteunis M. J. O. , Tavernier D.
Published: September 2010

Optically active threo‐(2S,4S)‐4‐mercapto‐2‐pentanol, erythro‐(2R,4S)‐4‐mercapto‐2‐pentanol and threo‐(2S,4S)‐pentanedithiol, were prepared from threo‐(2R,4R)‐pentanediol. The mechanism of their formation is discussed. The molecular optical rotation [M]Dof these compounds, of trans‐(4S,6S)‐, cis‐(4S,6S)‐dimethyl‐1,3‐oxathiane and of trans‐(4S,6S)‐dimethyl‐1,3‐dithiane, was determined and was related to the composition of the conformational mixture using Brewster's conformational rotatory power model.

A complete conformational analysis of the six 2‐(X)‐4‐(Y)‐substituted pentanes (X,Y = OH, SH) was obtained from their1H NMR spectra in combination with their chiroptical properties. The threo compounds favour the aa conformation, whereas the ag−/g+a forms are prefered in the erythro isomers, except for the 2,4‐diols where the intramolecular hydrogen bonded form is predominant.
Procédé de Fabrication D'Acide Phosphorique par Voie Humide a L'Hémihydrate Préparation de Diverses Formes D'Hémihydrates Utilises Comme Plâtre
Authors: Hambersin J. M.
Published: September 2010

We have summarized the different procedures described in the literature for the production of phosphoric acid of which the solid phase is either the dihydrate, the alphahemihydrate or the anhydrite.

In order to establish the operational parameters for the attack of the phosphate by sulfuric acid, it was necessary to examine the transition speed and the duration of the stability of the alpha‐hemihydrate in the system calcium sulfate‐phosphoric acid ‐ water in function of the temperature and the phosphoric acid concentration and to establish the equilibrium diagram basis for those results. The objective of our study was to examine the characteristics of the alpha‐hemihydrate which is used as plaster and which is formed by the attack of phosphate with sulfuric acid.

Thus, we have:

‐ examined the factors affecting the crystal dimensions and their mechanical properties

‐ compared the properties of the alpha‐hemihydrate “plaster” produced by the attack of phosphate by

) Beta‐hemihydrate “plaster” which is formed by dehydration of dihydrated sulfate by baking.

) Alpha‐hemihydrate “plaster” which is yielded by the dehydratation of calcium sulfate dihydrate in salt solution with or without the addition of auxiliaries.

In the workshop, one could, after filtration and washing, transform the alphahemihydrate into plaster plates or dry it preferably by a flashing procedure (by ascension tube) (40).
Trans‐ and CIS‐Effects in Cobaloximes. Part II The Crystal Structure of Trans‐(Chloro)BIS (Dimethyl‐Glyoximato‐N, N′)‐(Morpholine‐N) Cobalt(III)
Authors: Lenstra A. I. H. , van Loock J. F. J. , Tyrlik S. K. , Stapowska H.
Published: September 2010

The title compound, (CI) Co(dmgH)2(morpholine), crystallizes in the monoclinic system, space group P21/c with a = 9.031 (3), b □ 16.181 (5), c = 12.571 (4)Å, β = 93.33 (3)° and Z = 4. The structure was solved to R □ 0.074 for 2411 reflections. A comparison with (benzyl) Co(dmgH)2(morpholine) shows a marked trans‐influence on the Co‐N(morpholine) bond length, Co‐N being 2.022Å in the chloro and 2.11 Å in the benzyl complex.
Photoreactivite Acétalique en Serie Hétérocyclique et Osidique
Authors: Descotes G.
Published: September 2010

The acetalic photoreactivity of cyclic acetals was studied by some intramolecular acetalic hydrogen abstraction using photochemical ways (NORRISH. II type and BARTON ‐ like reactions).

The regioselectivities and stereoselectivities of these reactions were deduced from photochemical transformations of different tetrahydropyrannic cyclic ketoacetals, oxoalkglglycosides and hydroxyalkylglycosides.

The abstraction of γ‐acetalic hydrogen is not stereoselective by excited carbonyl groups but regiospecific to give lactones in good yields. With hydroxyalkyl hypoiodites, this γ‐H abstraction is stereoselective to yield anomeric orthoesters with predominant retention of configuration.

By δ‐acetalic hydrogen abstraction, the photocyclization of oxoalkylglycosides leads to hydroxy spiro ketals with retention of configuration. The influence of differents substrates, of carbonyl substituents and temperature effects were described. In osidic series (gluco, manno, 2‐deoxy), β‐anomers are more photoreactive than α‐ones.

All these results can be interpreted using stereoelectronic effects at the acetalic center for the photocyclization reactions.
Synthesis of some zinc(II), cadmium(II) and mercury(II) complexes with dibasic quadridentate schiff bases
Authors: Erinoso E. O. , Ghose B. N.
Published: September 2010

Six new complexes of Zn2+, Cd2+ and Hg2+ of the Schiff bases derived from biacetyl and ethanolamine, benzil and ethanolamine have been isolated. Their characterization is based on their analytical and spectral data.
Etude de la Texture des Nodules Oceaniques Par L'Analyse des Isothermes D'Adsorption‐Desorption D'Azote
Authors: Dodet Claude , Noville Francis , Crine Michel , Pirard Jean‐Paul
Published: September 2010

The porous texture of oceanic manganese nodules was studied by analysis of adsorption‐desorption nitrogen isotherms. The influence of calcination temperature on texture under nitrogen and hydrogen flows was determined.

The nodules are characterized by a very high specific area and could be a good catalyst for several reactions as hydrotreatment of heavy residues.
Synthese et Reactivite du [3, 2‐b] Pyridino [4, 5] Benzo‐1, 3a, 6, 6a‐Tetraazapentalene
Authors: Maquestiau A. , Flammang‐Barbieux M. , Vilain E. , Pfister‐Guillouzo G.
Published: September 2010

A new heteroaromatic pentalene, [3,2‐b] pyridino [4,5] benzo‐1,3a, 6, 6a‐tétraazapentalene [3] has been prepared by direct condensation of 2‐chloro‐3‐nitropyridine with benzotriazole followed by reductive cyclisation of the 1‐(3′nitro‐2′‐pyridyl) benzotriazole intermediate with triethylphosphite. The spectral and chemical properties of this new compound are described and the positions of the introduced substituents are determined as well by 1H NMR spectroscopy as by EHT calculations.
Spectres RMN‐1H de β‐Aminothiols, Disulfures et Thiazolidines Derivés de la Thioephedrine
Authors: Kone B. , Gelbcke M.
Published: September 2010

A series of β‐aminothiols and disulfides related to northioephedrine (N‐CH3; N‐C2H5; N‐iC3H7 and N‐t C4H9) and the series of the corresponding thiazolidine from paraformaldehyde have been synthesized. The study of their 1H‐NMR spectra allowed the differentiation of the diastereomers in these three series.
Digallic Acid
Authors: Verzele M. , Delahaye P. , van Dijck J.
Published: September 2010

Digallic acid was prepared by partial acid hydrolysis of tannic acid and purified by Counter Current Distribution. In water and methanol solution digallic acid is present in two isomeric equilibrium forms which were named meta and para digallic acid. Meta digallic acid, the main component, is stable in ether and acetone solution. The above was proved by HPLC, GC‐MS and NMR experiments on digallic acid and on its permethylation product.
Structure de la Preatroxigenine, Triterpenoïde Nouveau Isolé de Atroxima Afzeliana Oliv. (Ex Chod) Stapf
Authors: Babady‐Bila  , Warin R. , Delaude C. , Huls R.
Published: September 2010

A combination of oxidative and hydrolytic cleavage of atroximin, saponin isolated from the roots bark of Atroxima afzeliana, yields preatroxigenin (the postulated precursor of atroxigenin, atroxigenic acid and atroxigenic acid lactone(1)), p‐methoxycinnamic acid and 3,4‐dimethoxy cinnamic acid. The structures of these compounds are deduced from their physical, chemical and spectroscopic data. The sugars of the glucidic moiety of atroximin are identified from the perchloric acid hydrolysate.
Reactivity of Electrophilic Allyl Halides
Authors: Verhé R. , De Kimpe N. , De Buyck L. , Courtheyn D. , van Caenegem L. , Schamp N.
Published: September 2010

Reactions of allylic halides bearing two electron‐withdrawing groups in γ‐position with various nucleophiles (alkoxides, phenoxide, thiolates and cyanide) gave rise to substituted electrophilic cyclopropanes or ring‐opening products, depending upon the reaction conditions, the nature of the nucleophiles and the activating groups and the substitution pattern of the allyl halides. A kinetic study revealed that the reaction involved a nucleophilic addition as the rate determining step followed by a fast ringclosure.
The Preparation of Pure 2‐Thio‐Thiazolidine‐4‐Carboxylic‐Acid (TTCA) as a Reference Standard for Carbon Disulfide Exposure Tests
Authors: Rosier J. , Simonds R. , van Peteghem C. , Vanhoorne M.
Published: September 2010

2‐Thio‐thiozalidine‐4‐carboxylic‐acid is synthesized and subsequently purified by high‐pressure liquid chromatography. The spectral properties of the title compound are described and commented upon.
Structure and electronic spectra of small free radicals by quantummechanical methods
Authors: Bruna Pablo J. , Peyerimhoff Sigrid
Published: September 2010

Large‐scale multi‐reference configuration interaction calculations are carried out for the prediction of potential energy curves of several small radicals in their ground and excited valence‐shell and Rydberg states. The Gaussian AO basis employed therein is of double‐zeta plus polarization quality and includes up to f functions and semi‐diffuse p and d functions for proper description of charge‐transfer and correlation effects. Special emphasis is placed on AH and AH2 systems and their positive and negative ions with A=Si, P and S from the second‐row and on the distinctions relative to their first‐row analogues. Various properties such as spin‐orbit splittings and radiative lifetimes are also calculated. The importance of configuration interaction treatments for the correct prediction of the ordering of states in the transition metal hydrides ScH, ScH+, TiH and TiH+ is also pointed out. The relative stability of states in a large number of AB systems with A and B from the first and/or second‐row is discussed in light of their importance for larger systems with an AB center and with respect to their photoelectron spectrum which oftentimes does not allow the direct intercombination between ground states of neutral systems and their corresponding ions. The work should demonstrate the capability of today's theoretical ab initio methods for obtaining reliable information for small systems parallel or complementary to experimental studies.
Ionic Aromaticity as a Unifying Concept in Aromatic Reactivity
Authors: van Hooydonk Guido , De Keukeleire Denis
Published: September 2010

Ionic pi‐electron structures are used as a rationale for discussing aromatic electrophilic and nucleophilic substitution reactions. It is shown that an ionic representation of aromaticity is superior to the hitherto adopted system of resonating Kekulé structures. The observed orientation effects in aromatic substitution reactions are consistent with a general ionic reactivity scheme.
Empirical Relations for Coriolis Coupling Constants of XY3 Type of Molecules
Authors: Sengodan V. , Ramalingam P.
Published: September 2010

New empirical relations for computing the Coriolis coupling constants of some XY3 type of molecules have been proposed in terms of reduced mass and principal quantum number. The method of least squares is applied. The proposed relations yield very reasonable values and are comparable to the values obtained by the previous workers. Also the calculated values agree well with the experimental values.
Étude Vibrationnelle Des Trichlorures Organiques: (n‐C4H9)4NCl3, ϕ4AsCl3, C5H6NCl3, ϕ4PCl3
Authors: De Meyer M. , Levert J. M. , Vanclef A.
Published: September 2010

In this issue, we describe the synthesis and analysis of new trichloride compounds: tetraphenylphosphonium trichloride, (C6H5)4PCl3, and pyridinium trichloride, C5H6NCl3. Those are vibrationally studied and compared with tetrabutylammonium trichloride ((n‐C4H9)4NCl3) and tetraphenylarsonium trichloride. Raman spectroscopy shows an intense stretching band ν1 and 270 cm−1. Its straightforward intensity is explained by the preresonance spectra of the Cl3− ion.

Stretching constants of trichlorides and other trihalide ions (Br3−, I3−, BrCl3−, I2Br−, ICl2−) are compared each other.
Regioselectivity in the glutathione‐phenylglycidyl ether reaction: 1H NMR characterization of the adduct
Authors: De Bruyn André , De Keukeleire Denis , van Den Eeckhout Elfride , Baeyens Willy
Published: September 2010

A detailed 360 MHz 1H NMR analysis leads to the unambiguous structural identification of the compound, which is regioselectively formed in the chemical and enzymatical reactions between glutathione and phenylglycidyl ether. The thiol group attacks preferentially the least substituted oxirane carbon atom.
Structures Des Ions [M‐CH3]+ Provenant de la Fragmentation de la 2‐Heptanone Ionisée
Authors: Maquestiau A. , Flammang R. , Meyrant P. , Audier H. E. , Milliet A.
Published: September 2010

Collision‐induced dissociations‐mass analyzed ion kinetic energy (CID‐MIKE) spectrometry has been used to characterize [M‐CH3]+ ions from ionized 2‐heptanone. Acylium [CH3(CH2)5 C=0] ions are produced at short times (within the source), while protonated cyclohexanone is formed exclusively in the field‐free regions.
Novel Donor‐Acceptor Substituted Heteroaromatic Compounds
Authors: Gompper Rudolf
Published: September 2010

Vinamidinium salt can be converted via 1,5‐dipolar cyclization into electronrich thiophenes, pyrroles, thiazoles and imidazoles. Diazaquinoneiminium salts react with nucleophiles to methylenepiperazines and dihydropyrazines. Donor‐substituted 1,3,5,7‐tetrazocines, cyclopentadienylium and aza(diaza)cyclopentadienylium salts, though formally antiaromatic, are stable compounds.
Functionally Substituted Vinyl Carbanions Versatile Intermediates in Heterocyclic Synthesis
Authors: Schmidt Richard R.
Published: September 2010

Direct C‐lithiation of functionally substituted acrylates yields versatile intermediates for syntheses of butenolides, tetronates, α‐hydroxytetronates, pyrrolenines, cyclopentenones, oxalacetates and maleic acid derivatives. A wide variety of substituents are compatible with this lithiation: alkyl, aryl, electron‐donating and electron‐withdrawing substituents in α‐ or β‐position conducting to interesting regio‐and stereoselectivities. The compounds obtained are portions of many natural products. Approaches to the synthesis of aspertetronins, gregatins, ascorbic acids, chlorotricolide, and KDO will be outlined.
AlPO4‐Supported nickel catalysts. IV.‐Substituent effects in competitive hydrogenation of styrene and its α‐methyl derivative
Authors: Campelo J. M. , Garcia A. , Luna D. , Marinas J. M.
Published: September 2010

Styrene (S) and its α‐methyl derivative (MS) were competitively hydrogenated over a series of nickel catalysts supported on the AlPO4, AlPO4‐Al2O3 and AlPO4‐SiO2 systems, using methanol as solvent, under initial hydrogen pressure in the range 0.4‐0.6 MPa and temperatures between 288 and 323 K, obtaining the relative reactivities RMS,S and the relative adsorption constants KMS,S. The RMS,S and KMS,S values were less than unity in the range 0.04‐0.08 indicating that S was adsorbed more strongly and less hindered on these catalysts than MS.

With respect to the influence of temperature and pressure on competitive hydrogenation, the relative reactivity RMS,S was found to be independent of the initial hydrogen pressure while the changes of RMS,S with temperature followed and Arrhenius‐type law below a temperature limit. This limit, as well as the slopes and intercepts of the representation log RMS,S vs. T−1, depended on the supports.
Rotating Ring‐Disk Study of the Cu(II)/Cu(O) System on a Gold Electrode in Sulphuric Acid Solution
Authors: Vandenbruwaene J. , Kiekens P. , Temmerman E.
Published: September 2010

The reduction and oxidation reactions of the Cu(II)/Cu(O) system have been studied with a rotating gold ring‐disk electrode in 0.2 M sulphuric acid solutions.

Two reduction waves R1 and R2 are obtained. R1 is mainly attributed to the underpotential deposition of copper while R2 is associated with the convective‐diffusional formation of bulk copper metal.

Three oxidation (stripping) peaks O1, O2 and O3 are observed. O1 at most positive potentials, is thought to result from the oxidation of underpotential copper. The second stripping peak O2 may originate from the dissolution of copper atoms in direct contact with the underpotential copper, having slightly different properties with respect to the bulk copper atoms. Bulk copper is supposed to be oxidized in the third stripping peak, O3.
Iridoids: The Total Synthesis of the Aglucones of (±)‐8‐Epiloganin and (±)‐Mussaenoside Via Bicyclo |3.3.0| Octenes
Authors: Storme P. , Callant P. , Vandewalle M.
Published: September 2010

The nitrone‐olefin cycloaddition reaction has been used to construct cis‐fused bicyclo|3.3.0| octanes or diquinanes as potential intermediates for C‐11 functionalized iridoids. The isoxazolidine 7 was obtained in four steps from the commercially available 2‐cyclopentene‐1‐acetic acid 4. Different functionalized diquinanes 8 to 19 and 22 to 24 have been prepared. As illustrative examples of iridoid synthesis, compounds 21 and 26, the O‐methyl protected aglucones of (±)‐8‐epiloganin (2) and (±)‐mussaenoside (3) have been synthesized starting from the common key‐intermediate 11.
D.C., A.C. and Complex Plane Polarographic Behaviour of Copper (II) in Monoethanolamine, Sodium Perchlorate/Monoethanolammonium Perchlorate Solutions
Authors: Sridhar P. , Subrahmanya R. S.
Published: September 2010

A detailed investigation of d.c., a.c. and complex plane polarographic behaviour of copper (II) in mixtures of monoethanolamine and sodium perchlorate and monoethanolamine and monoethanolammonium perchlorate is made. In solutions containing monoethanolamine and sodium perchlorate, the reduction is found to be two‐electron addition process, the extended d.c. wave being due to more than one complex species in sluggish equilibrium. The a.c. and complex plane polarographic techniques show reduction due to only one of the species. The formula of the species is given on the basis of a.c. summit potential shift with change in ligand concentration. In solutions containing monoethanolamine and monoethanolammonium perchlorate, two 1:1 waves are obtained in d.c. polarography, the separation increasing with increase in monoethanolammonium perchlorate concentration. Corresponding to the two d.c. polarographic waves, the a.c. and complex plane polarograms also indicate two peaks. On the basis of complex plane polarography, the rate constants of the various processes have been determined. Based on the d.c. polarography, the formulae and stability constants of copper (II) and copper (I) complexes have been determined. The composition of the two complex species are given as CuM3OH+ and CuM+2.
Termination of CE(IV)‐Diacetone Alcohol Redox System Initiated Polymerization of Acrylonitrile by V(V): A Kinetic Study
Authors: Srinivas P. , Nageswar Rao K. , Sethuram B. , Navaneeth Rao T.
Published: September 2010

Polymerization of acrylonitrile (AN) initiated by Ce (IV)‐diacetone alcohol (DAA) redox system was studied in the presence of V(V). Rate of polymerization was decreased considerably by the addition of small amounts of V(V). Polymerization was not observed either by V(V) alone or by V(V)‐DAA redox system. Under the experimental conditions orders with respect to [Ce(IV)], [DAA] and [AN] were found to be 0.5, 0.5 and 1.5 in the absence of V(V) and these changed to 1.0, 1.0 and 2.0 respectively in the presence of V(V). Mutual termination of polymeric radicals in the absence of V(V) becomes linear termination with V(V) in the presence of V(V). A probable mechanism is proposed to explain the results.
Rates of Peptide Formation Involving Imino Acid Residues
Authors: Wante Dirk P. M. , Anteunis Marc J. O.
Published: September 2010

The determination of the rates for peptide coupling in tetrahydrofuran between Z‐Aaa‐OPcp (Aaa = Ala, (NMe)Ala, Pro, Thz, Pip and (S)Pip) and H‐Bbb‐OMe (Bbb = (NMe)Ala, Pro, Thz, Pip and (S)Pip) allowed us to evaluate the relative reactivities between these members, either as active components or as amino components. The reactivity of Pro (either as the active species or the amino component) equals that of (NMe)Ala. The reactivity of Pip and (S)Pip as imino components is low while the activation energy is raised by an amount that roughly equals the energy increment needed for bringing the carboxylate grouping from the equatorial to the axial position. The reactivities of these six‐membered residues are also appreciably low when being the active components during peptide coupling. The presence of a ring‐sulfur atom at γ‐position of nitrogen additionally decreases the rate for peptidation, especially if (S)Pip is the imino component.
Solubility Behaviour of Ionic Solid Solutions and Their Precipitation from Aqueous Solution
Authors: Driessens F. C. M. , Verbeeck R. M. H.
Published: September 2010

It is shown that the distribution of ions over the solid phase and an aqueous solution can be interpreted in terms of Roozeboom's classification in the case of ideal ionic solid solutions and regular ionic solid solutions with and without ordering or substitutional disorder. A general relation is derived between the distribution coefficient D of the system and the solubility products of the components of the solid phase. In this way D can be determined experimentally in an independent way. It appears that in practice type II and type III systems are indistinguishable from type I systems, when the distribution coefficient D differs about one order of magnitude or more from unity even in the case of good recryatallization. In those cases distribution diagrams are not suitable to derive the nature of the series of solid solutions involved.
Heats of Crystallization of CaSO4.2H2O
Authors: Deckers Jacques M. , Lash John E. , Burns Georges
Published: September 2010

The heat of crystallisation of Gypsus (CaSO4.2H2O) has been measured. At room temperature (23°C), from solutions whose initial concentration is greater than 0.4 sole 1−1 in CaSO4), an exothermic precipitation occurs with an enthalpy of crystallisation of −20.2 ± 0.5 KJ mol−1. From solutions whose initial CaSO4 concentration is less than 0.25 mole 1−1 the crystallisation process is endothermic, the enthalpy of crystallisation being +2.4 ± 0.2KJ mol−1.

Under microscopic examination the exothermically produced crystals appear as very thin needles, while the endothermic crystals are platelet like. The latter are identical to the crystals of gypsum found in nature. Analysis of all precipitates formed below 70°C, corresponded to the formula CaSO4.2H2O.

All precipitates have the same X‐ray powder spectra (Debye ‐ Scherrer). However, Differential Scanning Calorimetry produces distinct scans for the two types of precipitates obtained. The logical interpretation of these results is that there exists two distinct phases of CaSO4.2H2O. The existence of two phases of gypsum would explain why in some (but not all) tombs in the Valley of the Queens and the Valley of the Kings in Upper Egypt, the gypsum, serving as a base layer for mural paintings, has become dehydrated.
Gel Permeation Chromatography of Alkali Cations in Methanol Effect Of Macromolecular Ligands on the Volume of Elution
Authors: Horrion Jacques , Sonveaux Etienne
Published: September 2010

The gel permeation of low concentrations of salts of alkali metals on Sephadex LH‐20 using methanol‐acetic acid as eluent allowed resolution of binary mixtures of the salts. The addition of poly(ethyleneglycol) monomethyl ether (M.W. 5000) (PEG) to the mobile phase induced a large reduction of the volume of elution of potassium and rubidium but sodium was little affected. A PEG‐18‐crown‐6 conjugate was synthesized and the association constants of the crown with various cations were determined. The PEG‐crown conjugate did not further accelerate the cations as compared to PEG alone.
Interaction De Transfert De Charge En Photochimie Des Cétones, Une Étude Par Resonance Paramagnétique Électronique.
Authors: De Pauw E. , Collin J. E.
Published: September 2010

Electron spin resonance has been chosen to monitor the radical species occuring during photoexcitation of selected aromatic‐cetone charge transfer complexes. The identification of trapped intermediate radicals is presented and the relation between reactivity and electronic states of the complexes is deduced.