bluuebunny/crossref_metadata_2025 huggingface dataset:
Étude par Resonance Magnétique Nucléaire du Proton A Haut Champ des Méthyl‐4 Pyrazolines‐2
Authors: Elguero José , Fruchier Alain
Published: September 2010

For the first time the ABCM3X and ABCM3 systems of proton nmr spectra of two 4‐methyl‐2‐pyrazolines were analyzed. The studied compounds were 1–(2′, 4′‐dinitrophenyl)−4‐methyl‐2‐pyrazoline and 1‐(2′,4′‐dinitrophenyl)−3‐bromo‐4‐methyl‐2‐pyrazoline. The difficulty to analyze the spectra of 4‐substituted pyrazolines, compared with the analysis of 5‐substituted ones, is discussed.
Spectrophotometric Determination of Ti(IV) With 2‐Benzylideniminobenzohydroxamic Acid
Authors: Salinas F. , Mahedero M. C. , García‐Martín J. P.
Published: September 2010

A new method for the photometric determination of Ti(IV) with 2‐benzylideniminobenzohydroxamic acid is described with 50% ethanol and 0.5 M HCl medium, the complex shows an absorption maximum at 392 nm. The molar absorptivity value is 5.110 1.mol−1 cm−1 an it is possible determine between 2.0 and 6.0 ppm of Ti(IV). The method is applied to determination of Ti(IV) in a pharmaceutical drug.
Molecular Structure Analysis of Monoamine Oxidase Inhibitors: Moclobemide, p‐Chloro‐n‐(2 Ethylmorpholinium)‐Benzamide Chloride Monohydrate, C13H17N2O2Cl.HCl.H2O
Authors: Durant F. , van Der Brempt C. , Bufkens F. , Evrard G.
Published: September 2010

Mr=232.1, monoclinic, P21/c, a=13.504(1), b=15.805(1), c=7.369(1) Å, β=95.81(1)°, V=1564.7 Å3, Z=4, Dc=1.37 g.cm−3, Cu Kα, λ=1.54178 Å, μ=36.71 cm−1 F(0,0,0)=680.0, T=293 K, final Rw=0.059 for 2446 observed reflections (I≥2.5σ(I)). Crystal cohesion is assumed by intermolecular H‐bonds constraining a particular conformation of the title compound. The morpholinic nitrogen atom is protonated by an hydrochlorid acid molecule.
Nouvelles Méthodes de Déshalogènation et de Formation D'Éthers D'Enol Triméthylsilyliques Par Action de iPr2NLi Sur Quelques α‐Monobromo‐Et α, α'‐Dibromocétones
Authors: Lion Claude , Dubois Jacques‐Emile , Lebbar Khadija
Published: September 2010

Attemps to prepare 2‐bromo‐2, 4‐dimethyl, 3‐trimethylsiloxy 3‐pentene reacting lithium diisopropylamide (LDA) with 2‐bromo‐2, 4‐dimethyl‐3 pentanone have revealed two new reactions. After a few minutes quantitative yields are obtained of either the dehalogenated ketone (after hydrolysis) or the trimethylsilyl enol ether (after addition of trimethylsilyl chloride). These reactions are general and have been extended to other α‐monobromoketones and α,α'‐dibromoketones. In the latter case, the reaction is more complex and leads generally to dehalogenation or reduction products.
New Preparations of P‐Nitrophenylcyclopropane
Authors: Broos R. , Anteunis M. J. O.
Published: September 2010

The preparation of p‐nitrocyclopropylbenzene by reaction of dimethyloxosulfonium methylide with p‐nitrostyrene or p‐nitrobenzyl iodide (bromide) in 67 and 37 % yield respectively is reported.
Synthesis of Dibenzo[d,g] [1,2,4] Triazolo[4, 3‐a] [1,3] Diazocine‐8‐one and Dibenzo [d,g] [1,2,4] Triazolo [4,3‐a] [1,3] Oxazocine‐8‐One
Authors: Rahman Loay K. A.
Published: September 2010

Compounds (1)‐representatives of a new heterocyclic system were obtained by reaction of 3‐hydroxy‐,3‐chloro‐ and 3‐amino‐4‐phenyl‐1,2,4‐triazoles with iodobenzoic acid and N‐methylanthranilic acid followed by ring closure to give the parent compounds in good overall yield.
The Adsorption of Sulfur‐Compounds on Cu(II)Y Zeolite
Authors: Demertzis Mavroudis , Kovala‐Demertzi Dimitra , Vansant Etienne F. , Peeters Guido J. , Vanderheyden Els
Published: September 2010

The adsorption of H2S, CH3SH and CS2 on Cu(II)Y zeolite reveals an affinity sequence CH3SH » CS2 > H2S. Very strong displacement effects of CS2 and H2S by SH were observed when binary mixtures of CS2/CH3SH and CS2/H2S were contacted with Cu(II)Y. In ternary mixtures H2S is displaced by both, CS2 and CH3SH while CS2 is displaced by CH3SH. The interaction between the Cu(II)Y and the different S‐compounds is studied by infrared spectroscopy. A strong dissociative adsorption, creating new hydroxyl groups, is only observed for the CH3SH adsorption in the Cu(II)Y zeolite and reflects the high selectivity of Cu(II)Y for CH3SH compared to H2S and CS2.
Polarographic Behaviour of 2‐Pyrilideniminobenzohydroxamic Acid
Authors: Misiego A. Sánchez , Salinas F. , Guiberteau Cabanillas A. , Durán Merás I.
Published: September 2010

The polarographic DPP and DC techniques have been utilized to study the behaviour of 2‐pyrilideniminobenzohydroxamic acid (PIBHA). This reagent gives rise to two cathodic waves, the Ep of the first wave is‐1.07 V vs Ag/AgCl at pH 3.38 and the Ep of the second wave appeared at‐1.45 V at the same pH. The principal characteristics of these waves have been studied and the corresponding possible mechanisms of the electrode process for both waves have been proposed.
Contribution À L'Étude des Réactions de Combinaison des Radicaux Alcoyle Tertiaires en Phase Solide
Authors: Gourdin‐Servenière C. , Fontaine L. M. , Tilquin B.
Published: September 2010

Disproportionation/combination ratios of self‐reacting t‐alkyl radicals are estimated in solid phase at low temperature. The low temperature solid state limit was estimated to be 7–25, this value is considerably lower than ratios of the literature (100 to 500) and is compatible with the FISCHER limit in liquid state. In the present work, the ratios are determined by product analysis from the gamma radiolysis of isobutane.
Note on the Preparation of Very Active N,N‐Bis (2‐OXO‐3‐Oxazolidinyl)‐Phosphorodiamidic Chloride (Bop‐Cl), an extremely Effective Reagent for Peptide Formation
Authors: van Der Auwera C. , Anteunis M. J. O.
Published: September 2010

A preparation of high‐quality coupling reagent Bop‐Cl is reported. It fulfills the expectations of reproducibility in efficient peptide coupling reactions that are characterized by the formation of little side products and by a clean work‐up.
A Stereoselective Synthesis of Cis‐1‐Methyl‐3‐(3,4‐Dimethoxyphenyl)‐5‐Bromo‐7‐methoxy‐8‐hydroxy‐1,2,3,4‐tetrahydroisoquinoline
Authors: Badía D. , Domínguez E. , Iriondo C.
Published: September 2010

The title compound (7a) was stereoselectively synthesized from the brominated 1,2‐diaryl‐ethylamine (6c) and its configuration was unambiguously established on the basis of spectroscopic data.
Spectrophotometric Study of 2‐Oximinodimedone Dithiosemicarbazone‐ni(II) complex. Determination of ni(II)
Authors: Salinas F. , Jiménez Sánchez J. C. , Lemus J. L.
Published: September 2010

The spectrophotometric study of the orange 2‐oximinodimedone dithiosemicarbazone‐Ni(II) complex was made in dimethylformamide‐water solution (ϵ 440 nm=7200 l. mol−1. cm−1; stoichiometry 2:1 reagent to Ni(II) and apparent stability constant 1.0x106). A new method for the spectrophotometric determination of Ni(II) is proposed for concentrations between 0.36 and 6 μg ml−1.
The Role of Bone Mineral in Calcium and Phosphate Homeostasis
Authors: Driessens F. C. M. , van Dijk J. W. E. , Verbeeck R. M. H.
Published: September 2010

On the basis of the composition of the mineral in bone and the saturation level of blood plasma with respect to the slightly soluble calcium phosphates it is shown that normal tissue fluids are not supersaturated with whole bone but with the minerals of dead bone. The solubility controlling phase in living bone is octocalcium phosphate and the presence of this phase regulates the calcium and phosphate concentrations of the body fluids by simple physicochemical equilibrium.
The Importance of the Input Parameters in the Determination and Evaluation of 2200 M.S−1 (n,γ) Cross Sections
Authors: De Corte F. , Simonits A. , De Wispelaere A.
Published: September 2010

The activation method is applied to the determination of the 2200 m.s.−1 (n,γ) cross sections (0) for the reactions 184Os(n,γ) 185Sm(n,γ)155 Sm and 153Eu(n,γ) 154Eu. The results of these experiments, together with a critical literature survey, demonstrate the importance of reporting the input parameter data for (isotopic abundance), γ (absolute gamma intensity) and T (half life), which are strictly associated with the σ0‐output.
Analytical Aspects of the Determination of Chromium by Graphite Furnace A.A.S.
Authors: van Schoor O. , Deelstra H.
Published: September 2010

Ashing‐and atomisation curves of chromium and lifetime of uncoated and pyrocoated graphite tubes were determined. Interferences such as background absorption and the influence of acids, cations and chlorides on the atomisation of chromium were studied. Acids, recipients and homogenisation can be major sources of contamination; contamination by dust particles in the laboratory was found to be neglegible.
Determination of Magnesium and Calcium in Stabilized Zirconium Dioxide by Atomic Absorption Spectrometry
Authors: Carleer R. , van Poucke L. C. , François J.‐P.
Published: September 2010

A procedure is described which permits the determination of magnesium (< 4% (w/w)) and calcium (< 1% (w/w)) in zirconium dioxide by atomic absorption spectrometry. Two different dissolution methods are used and evaluated. In the first method the ZrO2 is dissolved in a mixture of concentrated HF, HCl and HNO3 acids in a teflon bomb, while in the second method the ZrO2 matrix is brought into solution with a (NH4)2SO4, concentrated H2SO4 mixture. The optimalization of the analytical parameters is studied. For both elements the method of standard addition is employed. Powders of ZrO2, partially sintered (600‐1000°C) and completely sintered (1650°C) ZrO2 tubes are analyzed with both optimized methods for magnesium and with the first method for calcium.
The Ph4AsPh4B Assumption for Single Ion‐Thermodynamics and its Asymmetric Partition to Cation and Anion
Authors: Kim J. I.
Published: September 2010

The partitioning of thermodynamic quantities of the reference electrolyte (Ph4AsPh4B) is discussed by comparing its standard free energies of transfer from water to organic solvents (ΔWSG°) with those for Ph4AsPh4B. From experiment in 14 different dipolar‐aprotic organic solvents, it is found that an asymmetric partition with the ratio: ΔWSG° (Ph4As+)/ΔWSG° (Ph4B−)=1.08 ± 0.02 is better justified than the equal partition practised in the literature. This asymmetry is mainly ascribed to the size difference between the reference cation and anion. The electrostatic contribution (ΔWSG°A(el)), primarily from iondipole interaction, does not appear as a cause for the asymmetry.
Nitric Acid Interaction with Marine Aerosols Sampled by Impaction
Authors: Otten Ph. , Bruynseels F. , van Grieken R.
Published: September 2010

Observed enrichments of NaNO3 in marine aerosols have been attributed to NaNO3‐formation during the sampling procedure in the case of filter sampling. This artifact was investigated for cascade impactor sampling. Experiments were carried out in which an air stream containing 1 μg HNO3 per m3 was led over 1‐2 μm NaCl‐particles deposited in an impactor. The morphology of the particles and the chemical composition of their core and surface layer was then investigated using laser microprobe mass analysis (LAMMA) and electron microprobe measurements. A definite NaNO3 formation was observed. It can, however, be avoided completely by placing a suitable denuder or pre‐stage in front of the impactor. Even with such a precaution, NaNO3 was still found in ambient marine aerosols over the North Sea. This can thus be attributed now with certainty to a previous atmospheric interaction of NaCl with HNO3.
The Determination of the Stability Constants of Mononuclear and Polynuclear Species of Mono‐ and Dicarboxylic Acids via Potentiometric Titrations
Authors: Bouserie Frank L. G. , Thun Harry P.
Published: September 2010

The potentiometric determination of the stoechiometric dissociation constants of mono‐ and dicarboxylic acids is certainly not hampered by unsophisticated calculation methods or experimental inaccuracies. The reliability of these constants is unsettled by a poor control of the activity coefficients during these experiments. In this paper, the variation of the activity coefficients as well as the effect on the dissociation constants and their determination is discussed.
Analysis of silicate rocks for Rb, Sr, Y, Zr and Nb by Energy‐Dispersive X‐Ray Fluorescence
Authors: Vanlerberghe L. , Hertogen J.
Published: September 2010

A procedure is described for accurate and precise routine analysis for the trace elements Rb, Sr, Y, Zr and Nb in silicate rocks by Energy‐Dispersive X‐Ray Fluorescence analysis with Ag secondary target excitation. The trace elements are analyzed on pressed powder pellets. Primary standardization is relative to international reference rocks and matrix absorption corrections are based on the Compton scatter method. The computer program for spectrum analysis incorporates advanced non‐linear least squares peak fitting techniques. Overall precision for a single measurement can be as good as 2% relative. Analysis of established U.S.G.S. reference samples AGV‐1, GSP‐1 and G‐2 shows that accuracies of better than 5% relative are obtained. Supplementary data for Zn, Ga, Pb and Th show poorer precision.
Synthesis and Characterization of n‐Alkylanilinium Octamolybdates. Identification of Some Products of Their Thermogravimetric Decomposition
Authors: Arnaiz A. R. , Santiago C. , Martinez M.
Published: September 2010

The compounds (BH)4Mo8O26 being B: anilinium, N‐methylanilinium, N,N‐dimethylanilinium and N,N‐diethylanilinium have been synthetized and characterized for the first time.

Thermogravimetric decomposition in isothermal and non‐isothermal regime have been studied. At temperatures between 480–560 K a great number of organic compounds, different from the initial organic bases have been identified, with molecular weight between 117–254 g mol−1.
Étude Théorique des Propriétés Électroniques et Électrochimiques de la Polyaniline
Authors: Brédas J. L. , Thémans B. , André J. M. , Silbey R. , Boudreaux D. S. , Chance R. R.
Published: September 2010

The electronic band structures of various neutral and charged forms of polyaniline are discussed. The MNDO semiempirical technique is used to determine the polyaniline chain geometries. Band‐structure calculations, based on those geometries, are then performed with the VEH method. We obtain theoretical estimates of ionization potentials, bandgaps, electron affinities and redox potentials which are in good agreement with experiment. We discuss in detail the electrochemical properties of polyaniline in aqueous media and the structural evolution of the polymeric chains upon oxydation and reduction. We propose a model for the electrochemical properties of polyaniline which is in excellent agreement with experimental data and theoretical predictions.
Synthèses et Synthèses Enantiosélectives D'Epoxydes Derivant du (E)‐Stilbène et de L'α‐Méthylstyrène Par la Méthode de Payne
Authors: Ben Hassine B. , Gorsane M. , Pecher J. , Martin R. H.
Published: September 2010

Epoxidation of (E)‐stilbene and α‐methylstyrene has been carried out using the (dl) nitriles 1, 2 and 3 in the presence of 98% H2O2. Chemical yields are collected in tables I and II (75–87%). The enantioselective epoxidation of the same substrates has been carried out using optically active 2‐cyano‐heptahelicene 4. Good chemical yields [(E)‐stilbene 92% and α‐methylstyrene 84%] and enantiomeric excesses [(E)‐stilbene 99.8%±2 and α‐methylstyrene 97.6%±2] have been obtained.
The ESR Spectrum Near G=2 of Carbonated Calciumapatites Synthesized at High Temperature
Authors: Callens F. J. , Verbeeck R. M. H. , Matthys P. F. A. , Martens L. C. , Boesman E. R. , Driessens F. C. M.
Published: September 2010

The ESR spectrum near g=2 of several carbonated calciumapatites synthesized at high temperatures, is studied as a function of incident microwave power. It is shown that the ESR signal observed is the composition of several powder spectrum contributions, arising from different paramagnetic centres. At low microwave power, the spectrum essentially reduces to be superposition of two very related spectra, probably to be ascribed to two CO33− radicals. The major component is assigned to CO33− at a phosphate site, while the other can be due either to a CO33− at a hydroxyl site or a surface CO33−.
The Dissociation of Monoprotic Acids. Influence of Composition Changes in the Solution on the Potentiometric Determination at Constant Ionic Strength
Authors: Rogiers Rony , Vantomme Paul , Bouserie Frank L. G. , Thun Harry P.
Published: September 2010

By use of a glasselectrode or a sodium ISE the authors try to determine secondary effects influencing the emf values when studying the dissociation of α‐OH‐isobutyric acid at I=1 and 25°C.
Intercalates With Linear Polymer Host. Part V. Optical Determination of the orientation of the guest molecules in [(CH2CH2O‐)10 (C6H4Cl2)3]n intercalates
Authors: Point J. J. , Coutelier Cl.
Published: September 2010

The orientation of pC6H4Cl2 in the [(pC6H4Cl2)3 (CH2CH2O)10]n crystalline intercalate previously studied by X‐Ray diffraction and FTIR spectroscopy, is obtained by measurement of birefringence of fibres of this compound.
Synthesis and Identification of Vicinal Azaoxo‐2(3)‐Homodiamantanes
Authors: Tinant B. , Declercq J. P. , van Meerssche M. , Janko J. , Burkhard J. , Hajek M. , Vodiĉka L.
Published: September 2010

The Schmidt reaction of diamantanone has been studied in details. The main products of the reaction were separated by means of the elution chromatography on silica gel. Obtained compounds 10‐aza‐11‐oxohomodiamantane (VI) and 11‐aza‐10‐oxohomodiamantane (IX) were analysed by X‐ray diffraction. These compounds as well as 5ax‐hydroxy‐and 5eq‐hydroxy‐3‐diamantanones were also analysed by using 13C NMR additive rules.
4,5‐Diphenylimidazoles from the Cyclization of Benzil N‐Alkylmonohydrazones
Authors: Collibee† William L. , Anselme Jean‐Pierre
Published: September 2010

The thermal cyclization of monodisubstituted hydrazones (1) affords the corresponding N‐substituted‐4,5‐diphenylimidazoles in good to excellent yields; possible mechanisms for this unusual cyclization are presented.
Citricolic Acid, a Novel Type of Fungal Metabolite
Authors: Ayer William A. , Dufresne Claude
Published: September 2010

Citricolic acid, a metabolite of the fungus Mycena citricolor, has been shown to possess structure 1. The structure was elucidated by a combination of physical and Chemical methods. Citricolic acid (1) is a new type of natural product which appears to be a degraded steroid. A possible biogenesis of 1 is discussed.
Sesquiterpenes with New Carbon Skeletons, Furoeremophilanes, Secoeremophilanes and other Constituents from Argentinian Senecio Species
Authors: Bohlmann F. , Jakupovic J. , Warning U. , Grenz M. , Chau‐Thi T. V. , King R. M. , Robinson H.
Published: September 2010

The investigation of ten further Senecio species afforded 24 new furanoeremophilanes, 18 eremophilanolides, seven seco‐ and two rearranged eremophilanolides, twelve bisabolone derivatives and six sesquiterpenes with new carbon skeletons which are most likely derived from the latter. Possible biogenetic pathways are discussed. Furthermore five new eremophilones, an eudesmane, four p‐hydroxyacetophenone, a bis‐coniferylalcohol derivative and five shikimic acid derivatives were isolated. The structures were elucidated by using highfield NMR techniques and other spectroscopic methods.
Sarains: A New Class of Alkaloids from the Marine Sponge Reniera Sarai
Authors: Cimino Guido , Stefano Salvatore De , Scognamiglio Gennaro , Sodano Guido , Trivellone Enrico
Published: September 2010

Reniera sarai, a marine sponge of the Ceractinomorpha subclass easily collectable in the Bay of Naples, is characterized by a series of cyclic nitrogenous compounds, which for many years have resisted all attempts of structural investigation.

Complex separation steps have now led to three new compounds, named sarain‐1, sarain‐2 and sarain‐3. Their structures have been partially determined mainly by a 500 MHz NMR study, utilizing the 1H‐1H homonuclear and 1H‐13c heteronuclear NMR Chemical shift correlation techniques. Sarains belong to a new class of pentacyclic alkaloids, containing in their skeletons a quinolizidine system linked to a tetrahydropyridine moiety. Two linear alkyl chains, placed between the two heterocyclic systems, supply the two remaining cycles. Recently a series of biologically active bis‐quinolizidine and 1‐oxa‐quinolizidine alkaloids have been isolated from the sponges Petrosia seriata and Xestospongia exigua, respectively. A common biogenetic origin should connect these alkaloids to sarains. Sarains show phase transfer catalytic properties.
Carotenoids of the Sponge Polymastia Granulosa (Hadromerida)
Authors: Hertzberg Sissel , Englert Gerhard , Bergquist Patricia , Liaaen‐Jensen Synnøve
Published: September 2010

The background information on natural carotenoids (new aspects), NMR spectroscopy of carotenoids (present status) and sponge chemosystematics, relevant to the present study, is briefly reviewed.

The quantitative carotenoid composition of Polymastia granulosa has been determined by methods including TLC, HPLC, VIS, 1H NMR and MS.

Isorenieracistene (7‐cis‐φ,φ‐carotene) was the major carotenoid, further characterized by 2D 1H NMR (400 MHz), and isomerization studies. Its stability is discussed.

The 1 H NMR spectrum of 7,9'‐dicis isorenieratene, a likely isolation artifact, was fully assigned by 1D Double Indor Difference experiments and 2D 1H NMR.

All three reports on Δ‐cis aryl carotenes concern sponges of the order Hadromerida. Possible cis hydrogenation of algal carotenoid precursors is considered.
Starfish Saponins XXX. Isolation of Sixteen Steroidal Glycosides and Three Polyhydroxysteroids from the Mediterranean Starfish Coscinasterias Tenuispina
Authors: Riccio Raffaele , Iorizzi Maria , Minale Luigi
Published: September 2010

Sixteen steroidal glycosides have been isolated from the starfish Coscinasterias tenuispina. The more polar components are the “asterosaponins” 1A–1E, 2A–2C, 3E and 3G, consisting of a Δ9(11)‐3β,6α‐dihydroxysteroidal moiety, a pentasaccharide portion attached at C‐6 and a sulphate group at C‐3. Compounds 1C, 2C and 1D are new saponins assigned as the tenuispinoside A through C. The second group of polar glycosides consists of two new xylose saponins, possessing monosulphate polyhydroxysteroidal aglycones and two new 4‐O‐sulphated glucose saponins, assigned as the coscinasteroside A through D (4–2). The less polar glycosides are the new “non‐sulphated” xylosides 8 and 9, designed as coscinasterosides E and F.

The structures of the new saponins were determined by extensive 1H and 13C NMR investigations, FAB mass spectroscopy, and by comparison with known compounds. The location of the sulphate ester functionalities in 4–7 were assigned on comparison of their spectral data with those of the corresponding desulphated analogues. C. tenuispina also contains three new monosulphated polyhydroxysteroids, which were assigned the structures 10 to 12.
Synthesis of Radiolabeled Juvenile Hormone Analogs and Chiral Homologs
Authors: Eng Wai‐Si , Prestwich Glenn D.
Published: September 2010

Radiolabeled juvenile hormone (JHs) and labeled JH derivatives are required for the study of JH metabolism and JH‐protein interactions as well as JH radioimmunoassay in insects. The progress in the synthesis of these labeled compounds for the last five years is reviewed, including the preparation of photoaffinity labels, enantiomerically enriched JH I and JH II with 3H labels, and radioiodinated analogs of JH I, methoprene and phenoxyphenyl ether insect growth regulators (IGRs). Experimental details are given for the efficient synthesis of two 3H‐labeled photoactivatable JH analogs, EFDA and EFTP, their photolysis in methanol, and their competitive binding assays performed on the Manduca sexta JH binding proteins (JHBP).
Novel Heterocycles by the Malonic Ester Variation of the Japp‐Klingemann Reaction
Authors: Heckendorn Roland
Published: September 2010

Azocompounds prepared by coupling malonic ester derivatives with diazotized anilines, 3‐amino‐2‐chloropyridine, anthranilic ester or 2‐aminobenzophenones are shown to be versatile intermediates for the synthesis of various polyaza‐heterocycles.
XIIth European Colloquium on Heterocyclic Chemistry “Phosphorus azides, powerful reagents in heterocyclic chemistry”
Authors: Majoral Jean‐Pierre , Bertrand Guy , Ocando‐Mavarez Edgar , Baceiredo Antoine
Published: September 2010

The Curtius type rearrangement is effective for tetracoordinated and pentacoordinated phosphorus azides. Competitive nitrene‐type reactions sometimes occur. On the other hand, irradiation of tricoordinated phosphorus azides lead to the generation of phosphorus nitrogen triple‐bonded species. The photolysis or the thermolysis of all these derivatives appears to be a convenient route for the synthesis of new heterocyclic compounds.
Biomimetic Oxidation of Hydrocarbons and Drugs by Metalloporphyrinic Systems
Authors: Mansuy D. , Battioni P.
Published: September 2010

Most biological oxidations of exogenous compounds, such as drugs and endogenous compounds, especially when the hydroxylation of an inert C‐H bond is involved, are catalyzed by cytochrome P‐450‐dependent monooxygenases. These enzymes have the unique ability to transfer an oxygen atom from oxygen atom donors including O2 into almost any organic substrates including alkanes in a highly selective manner. Based on the knowledge of the mechanisms of substrate oxidation by these cytochromes, chemical model systems using metalloporphyrin catalysts have been built. In particular, a very efficient system for hydrocarbon oxidation by H2O2 in mild conditions is described. It is also shown that Fe‐ and Mn‐porphyrins catalyze the transfer of the NR nitrene moiety of PhI=NR compounds into hydrocarbons leading to direct aziridination of alkenes and amidation of alkanes with high yields.
Studies With Coenzyme Model Systems
Authors: Pandit U. K.
Published: September 2010

The chemistry and applications of models of tetrahydrofolate and pyridine nucleotide coenzymes are discussed.
Applications of N‐Sulfinyl Dienophile Diels‐Alder Cycloadditions to Synthesis of Unusual Amino Sugars
Authors: Weinreb Steven M. , Gainor James A. , Joyce Richard P.
Published: September 2010

The amino sugar moieties of staurosporine and nogalarol have been stereospecifically synthesized by a strategy utilizing N‐sulfinyl Diels‐Alder chemistry.
Intermolecular Charge‐Transfer Complexes of Arylthiourea Derivatives
Authors: Nour El‐Din Ahmed M.
Published: September 2010

Intermolecular charge‐transfer complexes between arylthiourea derivatives and tetracyanoethylene in methylene chloride at 25°C have been studied spectro‐photometrically in the visible region. The spectral data indicate that the complexes are weak and the Ph‐N‐CS‐N moiety is responsible for complexation with tetracyanoethylene. Job's method shows that the stoichiometric ratio of the complexes is 1:1. The ionization potentials of the donors were calculated from the energy of charge transfer transitions.
Adsorption of Malathion on Activated Sepiolite from Cyclohexane Solution
Authors: González‐Pradas E. , Villafranca‐Sánchez M. , Plaza‐Capel R. J. , Del Rey‐Bueno F.
Published: September 2010

Adsorption of malathion on four natural sepiolite samples activated by different combined acid and heat treatments (0.25 N and 0.5 N, HNO3; 110°C and 200°C) from cyclohexane, has been studied. The adsorption isotherms may be classified as H‐3 type of the Giles classification which suggests that malathion molecules are strongly adsorbed on the sepiolite samples and that there is no competition from solvent for adsorption sites. The experimental data points have been fitted to the modified B.E.T. equation in order to know the adsorptive capacities (Xm) of the solids as well as their surface areas (S) available to the malathion molecules.

Xm values range from 1.35x10−1 molxKg−1 up to 2.47x10−1 molxKg−1, the maximum values corresponding to the sample activated with 0.5 N HNO3 solution and treated at 110°C. S values range from 70x103 m2xKg−1 up to 128x103 m2xKg−1, the maximum values also corresponding to the sample activated with 0.5 N HNO3 solution and treated at 110°C.
Modulation de la Régiosélectivité Lors de la Cycloaddition de la Diphénylnitrilimine Sur Divers Dihydro‐1,2 Naphtalènes Substitues, Stéréospecificité de la Réaction
Authors: Tshiamala Kabula , Kitane Saïd , Vebrel Joël , Laude Bernard
Published: September 2010

In order to control the regiochemistry of the cycloaddition of diphenylnitrilimine on 1,2‐dihydronaphtalene and at‐1 or −2 substitued derivatives and to obtain either regioisomer, we introduce a methoxycarbonyl group at the 4− or 3− position of the dipolarophile. The reactions are thus highly regioselective or specific.

Moreover each reaction is stereospecific and the approach of the dipole occurs from the less hindered diastereotopic side of the dipolarophile.
Étude Par Spectrométrie de Masse en Tandem D'Ions [C6H12O]+. Isomères
Authors: Beynon J. H. , Flammang R. , Kingston E. E. , Maquestiau A.
Published: September 2010

Ion kinetic energy spectrometry using two triple sector instruments has been used for the study of the fragmentation of ionized 5‐nonanone. Mixtures of isomeric [C6H12O]+. ions are formed in the first McLafferty rearrangement whose relative proportions depend on their internal energy.
Redox Potentials of Mixtures of Aldrithiol‐2 with 2‐Mercaptopyridine
Authors: Antelo J. M. , Arce F. , Sastre M. , Varela A.
Published: September 2010

The redox characteristics of mixtures of aldrithiol‐2 with 2‐mercaptopyridine have been studied in the range pH 0.3‐8.4 using a platinum electrode. Reversible two‐electron reactions were observed. In these mixtures the graphs of “formal potential” against pH depend on the various acid‐base equilibria present. The results show that for a given value of pH the “formal potential” measured is more positive than that determined polarographically using a dropping mercury electrode.
Molecular Structures of the Internal Acetals Derived from (1S, 10S)‐ and (1R, 10R) ‐ Dihydroxy‐3β‐Acetoxy‐5, 10‐Seco‐5‐Cholestanones
Authors: Tinant B. , Declercq J. P. , van Meerssche M. , Lorenc Lj. , Mihailovic M. Lj.
Published: September 2010

The molecular structures of the acetals 3b and 5a, obtained from (Z) ‐ 38‐ acetoxy‐5, 10‐seco‐cholest‐1 (10)‐en‐5‐one (1) via the cis‐(1S, 10R)‐epoxide 2, and from (E)‐3β‐acetoxy‐5, 10‐seco‐cholest‐1 (10)‐en‐5‐One (4) via the corresponding (1S, 10S)‐ and (1R, 10R)‐osmate esters, have been determined by X‐ray analysis.
Synthesis of Carbomethoxydiphenyl Sulfones, Mass and Proton‐NMR Spectral Studies
Authors: Briñón M. C. , De Bertorello M. M. , Bertorello H. E. , Luna L.
Published: September 2010

Four carbomethoxydiphenyl sulfone compounds are formed in the reaction of 4,4′‐dibromo (I) and 4,4′‐diiododiphenyl sulfone (II) with n‐butyllithium in tetrahydrofuran at ‐60°C. Their mass and proton‐nuclear megnetic resonance spectra are discussed.
Le 1,2,2‐Trichloronitrosoéthylène Comme Dienophile ou Hétérodiene en Cycloadoition de Diels‐Alder
Authors: Ascherl B. , Kresze G. , Vaerman J. L. , Vandenbulcke‐Coyette B. , Viehe H. G.
Published: September 2010

1,2,2‐trichloronitrosoethylene reacts either as dienophile or as a heterodiene depending on the nature of its partners in the Diels‐Alder reaction.
Synthèse et Hererocyclisation des (Pyrazolyl‐3(5))‐2 Benzimidazoles en Catalyse Par Transfert de Phase
Authors: Essassi E. M. , Fifani J.
Published: September 2010

Fusion of o‐diamines with pyrazolylhydrazides 2a‐2b gives the new 2‐pyrazolylbenzimidazoles 3a‐3l. The application of phase transfer catalysis to the N‐alkylation of compounds 3a‐3d leads to pyrazines 4a‐4d and diazépines 5a‐5d.
Deoxygenation of Cresol on Houdry and Modified Houdry Catalysts
Authors: Jachintha M. A. , Rajadurai S.
Published: September 2010

Physico chemical characterization of the Houdry catalyst supplied by the Houdry corporation, New Jersey shows that it is an amorphous form of silica alumina containing traces of calcium and potassium. It is modified by heat treatment and by loading strong metal oxides such as MoO3 and NiO. The catalytic activity for the deoxygenation of o− cresol on these systems were studied at 623 K. Very high percentage conversion (90%) was obtained on Houdry catalyst. However the conversion is not significantly altered by heat treatment of the catalyst in the temperature range 623 K to 723 K. The incorporation of the MoO3 in the catalyst enhances the activity. The MoO3‐NiO impregnation further increases the percentage conversion of cresol. The increase in percentage conversion on these strong metal supported catalysts may be due to the addition of the multivalent metallic active sites for the cresol to be adsorbed on the surface through oxygen coordination.
Sedum Alkaloids. IX1. Isolation from sedum acre and x‐ray structure determination of lobelanidine glycoside
Authors: Piccinni‐Leopardi C. , Tinant B. , Declercq J. P. , van Meerssche M. , Hootelé C.
Published: September 2010

Lobelanidine occurs in Sedum acre as the glycoside 1 whose complete structure has been established by spectroscopic and X‐ray diffraction methods.
Intramolecular Diels‐Alder Reaction with Furan‐Diene. Activated Allene as Dienophile in a BCD‐ring Approach to Steroids
Authors: Missisen Patrick , De Clercq Pierre J.
Published: September 2010

In connection with the total synthesis of corticosteroids and some triterpenoids the intramolecular Diels‐Alder reaction of furans 7 and 9, possessing an activated allene as dienophilic side chain, is investigated, and compared with the cycloaddition of the analogous α, β‐unsaturated enone 5. Differences in stereoselectivity are ascribed to the enhanced exothermicity of allene dienophiles. Observed reactivity differences and the stereochemical outcome are rationalized on the basis of an asynchronous reaction course. Most important, the allene dienophile allows for carbon elongation in β ‐position of the dienophile 5 without loss of reactivity in the cycloaddition.
A Simple Preparation of Cyanosilanes from the Corresponding Chloroderivatives by Transcyanogenation
Authors: Becu Chr. , Anteunis M. J. O.
Published: September 2010

Quantitative yields of pure cyanosilanes are obtained from the corresponding chlorides by transcyanogenation with cyanotrimethylsilane under catalysis of a small amount KF. This is the most direct method with minimum handling in order to obtain these moisture‐sensitive derivatives.
Trimethylsilyl Cyanide in Peptide Strategies. Part III. Needlessness for complementary hydroxyl side‐chain protection
Authors: Anteunis M. J. O. , Becu Chr. , Becu F. , Callens R.
Published: September 2010

No extra side‐chain protection is needed for Ser, Thr, Tyr and Cys (nor for Asp and Glu) in peptide syntheses that are mediated by TMS‐CN, whereby silylesters and ethers are formed and are stable enough even during activation of carboxylic components. This allows Head‐to‐Tail elongation strategies and fragment condensations without recourse to additional side‐chain protection except for amine and amide functionalities. Moreover, stereomutation during the H‐t‐T preparation of Z‐Trp‐ Ser‐Tyr‐OH and Z‐Ser‐Tyr‐Gly‐OH is almost absent.
The Dynamics of Biomineral Systems
Authors: Driessens F. C. M. , Borggreven J. M. P. M. , Verbeeck R. M. H.
Published: September 2010

Evidence accumulates that mineralization in the body, whether physiological or pathological, takes place only, when and where body fluids become supersaturated with respect to the formation product of fast nucleators like brushite, octocalcium phosphate, calcite and calcium oxalates. In the pH ranges above 8.0, between 8.0 and 7.0 and below 7.0 the most frequently occurring nucleating phases are calcite, octocalcium phosphate and brushite, respectively.

After nucleation of brushite this phase is transformed spontaneously into a mixture of a sodium‐ and carbonate containing apatite, of dolomite and of calcium deficient hydroxyapatite. After nucleation of octocalcium phosphate that phase is transformed spontaneously into a mixture of a sodium‐ and carbonate containing apatite, of magnesium whitlockite and of heavily carbonated calcium deficient hydroxyapatite. In addition, other phases can be formed in the presence of enough fluoride, zinc, etc.
Attempted Synthesis of the Dithiophene Analogs of Biphenylene
Authors: Párkányl Cyril , Huang Deeng‐Lih , Kalsotra Bansi L. , Jeffries Alfred T. , Lloyd Winston D.
Published: September 2010

Synthesis of the four possible dithiophene analogs of biphenylene (1), viz., cyclobuta[1,2‐b:3,4‐d′]dithiophene (3), cyclobuta[1,2,‐b:3,4‐b′]‐dithiophene (4), cyclobuta[1,2‐b:3,4‐c′]dithiophene (5), and cyclobuta‐[1,2‐c:3,4‐c′]dithiophene (6) has been explored using several different approaches. All these attempts have been unsuccessful similarly as the former efforts of Mc Omie and Wynberg. Equally unsuccessful were the attempts to obtain the iron tricarbonyl complexes of these compounds which were thought to be more stable. The HMO calculations carried out for cyclobutadithiophenes indicate that these four compounds will be highly unstable, also in view of the considerable ring strain.
Crystal Structure and Conformation of Short Linear Peptides: Part I: L‐Phenylalanyl‐Glycyl‐Glycine
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M.
Published: September 2010

C13H17N3O4, Mr = 279.30, orthorhombic, P212121, a = 5.743(2), b = 16.072(10), c = 15.317(10)Å, V = 1347(1)Å3, Z = 4, Dx = 1.38 g. cm−3, MoKα, λ = 0.71069 Å, μ = 1.12 cm−1, F(000) = 592, T = 291K, R = 0.036 for 1372 observed reflections. The molecule partly assumes a 310‐helical conformation. The side chain of the Phe residue has an unusual conformation characterized by angles X1 = 176° and X21 = 53°.
Ba(OH)2 as the Catalyst in Organic Reactions‐Part X‐Reaction of Chalcone with Hydroxylamine
Authors: Sinisterra J. V. , Marinas J. M.
Published: September 2010

The reaction of several chalcones with hydroxilamine has been studied. A systematic catalytic study of the synthetic process has been accomplished. The different experimental conditions have been studied. The process catalyzed in the homogeneous phase gives mixture of products. Nevertheless the process catalyzed by activated barium hydroxide catalyst, C‐200., in heterogeneous phase, produces Δ2 ‐isoxazolines with high yields and selectivities. The ‐ mechanism of the process in the heterogeneous phase is discussed. The poisoning effect on the C‐200 active sites, produced by an excess of NH2OH is analyzed. Some reactions products are described by the first time.
Synthesis of 7,8‐Didehydro‐3,4‐Dimethoxy‐17‐Methylmorphinan‐6‐one and the Regioselective Reduction of the Keto Function (Chemistry of Opium Alkaloids, Part XXIV)
Authors: van Gurp R. A. , Lie T. S. , Mense C. , Maat L.
Published: September 2010

7,8‐Didehydro‐3,4‐dimethoxy‐17‐methylmorphinan‐6‐one (2) was prepared by reductive opening of the epoxy bridge of codeinone, followed by methylation with Rodionow's reagent. Reduction of the title compound with sodium tetrahydroborate in the presence of cerium(III) chloride afforded a mixture of 7,8‐didehydro‐3,4‐dimethoxy‐17‐methylmorphinan‐6α‐ol (3) and ‐6β‐ol (4) in a ratio of 4:1 from which the 6α‐epimer was crystallized and converted into the acetate (7).
Crystal Structure and Conformation of Short Linear Peptides Part II: L‐Tryptophanyl‐Glycyl‐Glycine Dihydrate
Authors: Wu S. , Tinant B. , Declercq J. P. , van Meerssche M.
Published: September 2010

C15H1N4O4, 2H2O, Mr = 354.41, orthorhombic, P21 21 21, a = 9.019(8), b = 7.909 (3) c = 24.336(23) Å, Z = 4, Dx = 1.36 gcm−3, MoKα, λ = 0.71069 Å, μ = 1.14 cm−1, F(000) = 752, T = 291K, R = 0.061 for 1014 observed reflections. The molecule adopts a conformation somewhat similar to a segment of a lefthanded α‐helix. The side chain of the Trp residue takes an usual conformation described by χ1 = ‐172° and χ21 = ‐79°.
Syntheses and Spectral Characterization of the Metabolites of a New Organo‐Selenium Drug: Ebselen
Authors: Lambert C. , Cantineau R. , Christiaens L. , Biedermann J. , Dereu N.
Published: September 2010

The syntheses and spectral characterization of the metabolites of a new organo‐selenium drug (ebselen) are described.
Synthèse et Étude de l'Ouverture du Cycle de Sélénoloisothiazoles Bicycliques
Authors: Onyamboko N. V. , Renson M. , Paulmier C.
Published: September 2010

Condensed selenophenes on the one hand, and isothiazoles or isoselenazoles on the other hand, show a ring opening by organolithium compounds. We studied here the competition of ring opening in two isomers of the bicyclic unsubstituted system, selenoloisothiazole. Synthesis of these unknown isomers, namely selenolo[3,2‐d] and [2,3‐d] isothiazoles, and of the corresponding selenolo[2, 3‐d] isoselenazole, is described.
Solvent Effect Upon Dipole Moment and Proton Transfer Equilibrium in Ortho Mannich Bases
Authors: Pawelka Z. , Rospenk M. , Sobczyk L.
Published: September 2010

The dipole moments of ortho Mannich bases containing intramolecular OH…N hydrogen bonds were determined in solvents of various electric permittivity. The dipole moment of 2‐(N,N‐diethylaminomethyl)‐3,4,6‐trichlorophenol does not depend on the solvent polarity and simultaneously no contribution of the proton transfer form was detected in ultraviolet‐visible spectra. The dipole moments of 2‐(N,N‐diethylaminomethyl)‐3,4,5,6‐tetrachlorophenol and 2‐(N,N‐diethylaminomethyl)‐4‐nitronaphtol‐1 increase distinctly with the solvent polarity. The dipole moment enhancement can be quantitatively correlated with the displacement of the OH…N ⇄ O−…H‐N+ equilibrium towards the more polar proton transfer form. The solvent influence on the free energy of the proton transfer process, ΔGPT is discussed in terms of various effects.
The Effect of Some Additives on the Aggregation of Dyes
Authors: Abd El Wahed M. G. , Abd El Kader A. K. , Killa H. M.
Published: September 2010

The effect of additives such as ethanol, urea and KCI on the aggregation behaviour of C. I. acid red 13 and H. acid azonitrobenzotriazol dyes has been studied polarographically. The influence of surface active substances such as albegal B, uniperol O as well as levapon AN was also investigated. The thermo‐dynamic parameters ΔG, ΔH and ΔS were calculated using van't Hoff's equation. The results indicate that the electroreduction process proceeds irreversibly and is diffusion controlled.
Accuracy in Single‐Crystal X‐ray Diffractometry: Software Checks of Scan Angle, Mechanical and Electrical Stability of the Diffractometer from Intensity Profiles
Authors: Verbruggen M. , Lenstra A. T. H.
Published: September 2010

Software tests checking the diffractometer stability and the correctness of instrument settings are developed. Using averaged reflection profiles systematic underestimates of the scan angle can be detected and their effect on the background corrected with the help of α1/α2 splittings. Mechanical instabilities of the apparatus cause the center of a reflection profile to deviate from the expected value. Factors are described influencing the expected center, its spread and the accuracy of the experimental center. Mechanical errors appear to be rare. Statistical criteria are given to detect and correct background detector channels suspect of being effected by electrical instabilities. We estimate that in our experimental environment 1‐2% of all detector channels are likely to be enlarged by (external?) electrical error sources. A least‐squares analysis of Al2O3 shows that a correction of suspected backgrounds results in a 5% decrease of Σ|Δ|2 and a 1% increase of Σ|F0|.
X‐Ray Structure of 2‐Acetoxy‐1‐(4‐Nitrophenyl) Ethanone C10H9NO5
Authors: Tinant B. , Declercq J. P. , Exner O.
Published: September 2010

Mr = 223.18, monoclinic, P21/c, a = 9.004 (2), b = 12.552 (2), c = 9.416 (3) Å, β = 102.18 (2)°, V = 1040.1 (3) Å3, Z = 4, Dx = 1.43 g. cm−3, CuKα, λ = 1.5418 Å, μ = 10.13 cm−1, F(000) = 464, T = 291K, R = 0.044 for 1200 observed reflections. The two moieties of the molecule are planar and the dihedral angle between them is 79°.
Crystal Structure and Conformation of Short Linear Peptides: Part VI: L‐Alanyl‐L‐Prolyl‐Glycine Monohydrate
Authors: Wu S. , Declercq J. P. , Tinant B. , van Meerssche M.
Published: September 2010

C10K17N3O4, H2O, Mr = 261.28, orthorhombic, P212121, a = 6.716(1), b = 11.780(1), c = 16.248(1)Å, V = 1285.6(2)Å3, Z = 4, Dx = 1.35 g. cm−3, CuKα, λ = 1.5418 Å, μ = 9.28 cm−1, F(000) = 560, T = 291K, R = 0.063 for 2447 observed reflections. The molecule (hereafter APG) adopts a collagen‐like conformation at Pro residue with (φ2, Ψ2) values of (‐66.6°, 156.9°) and an extended form at the two terminal residues. The pyrrolidine ring is disordered with two positions for C(6) its conformation is C2‐Cγ‐endo for the major component (75%) end C2‐Cγ‐exo for the minor one (25%). The geometry and the main‐chain conformation are both in excellent agreement with those found in the tripeptide L‐Leu‐L‐Pro‐Gly monohydrate (hereafter LPG)(1,2) It seems that the atoms further than Cγ of the Leu side chain do not affect significantly the conformation of peptide backbone in this case. The twofold screw axis in the LPG crystal structure corresponds to that of the APG in the a direction.
The Effect of Added Electrolytes on Amphiphilics in Aqueous Solution: Data Motiving a Differentiation Between the Action of Anions and Cations
Authors: Vijlder Michel De
Published: September 2010

The sequences of electrolyte effectiveness in altering the behaviour of two still closely related azo dye homologues Benzyl Orange (C6H5‐CH2‐NH‐C6H4‐N‐N‐C6H4SO3−) and Orange IV (C6H5‐NH‐C6H4‐N‐N‐C6H4SO3−), obtained from spectrometric measurements, are different.

The extension of earlier data 1,2,3 on the effect of electrolytes with various anions affirms the differentiating action of anions and cations: anions do specifically influence the ordening of the water structure while cations differ in their ion pair formation tendency. Both processus induce a self‐association of the dyes3.
Crystal Structure and Conformation of Short Linear Peptides: Part VIII: L‐Leucyl‐L‐Tryptophanyl‐L‐Leucine Hydrochloride Dihydrate
Authors: Wu S. , Declercq J. P. , Tinant B. , van Meerssche M.
Published: September 2010

C23H35N4O4 +Cl−.2H2O, Mr = 503.08, orthorhombic, C2221, a = 21.661(4), b = 22.820(4), c = 12.568(2)Å, V = 6212(2)Å3, Z = 8, Dx = 1.08 g. cm−3, CuKα, λ = 1.5418 Å, μ = 14.12 cm−1, F(000) = 2160, T = 291K, R = 0.078 for 3133 observed reflections. The molecule assumes a poly‐Gly‐II type conformation with (ϕ2,Ψ2) values of (‐75°,‐135°). The two C atoms of the methyl groups of Leu(2) side chain are disordered with two positions for each (56%,44%). The side chain of Leu(1) and the minor component of Leu(2) have the similar conformation characterized by (X1, X21, X22) angles of (‐71°,‐56°,‐179°) and of (‐77°,‐33°,174°) respectively, close to one of the most frequently observed ones (‐60°,‐60°, 180°) (1). The corresponding values of the major conformation of Leu(2) are unusual (‐77°,44°,142°). The Trp side chain takes an energically defavorable conformation (X1 = 63°, X21 = ‐15°, X22 = 164°) with the indole ring almost parallel to the CαCβCγ plane instead of being perpendicular to it(2).
Electrochemical and Photochemical Preparation of N‐Acylated a‐Methoxy‐Phenethylamine. Failure to Conversion into Phenylalanine
Authors: Callens R. , Anteunis M. J. O. , De Witte M.
Published: September 2010

Anodic oxidation of N‐methoxycarbonyl phenetylamine in MeOH at pH 9 proceeds quantitatively although only 45% conversion can ba reached in a simple undivided electrocall as the result of the formation of an obstructing precipitate. Treatment of several N‐acyl‐a‐methoxy derivatives with cyanide results in elimination instead of substitution. The preparation of Phe from the above‐mentioned synthons therefore was unsuccessfull.
Décomposition des Esters de la N‐Hydroxythiopyridone‐2. Synthèse de Quelques Nouveaux Halogènures Secondaires et Tertiaires Encombres
Authors: Stofer Edwond , Lion Claude
Published: September 2010

Hindered α,α‐disubstituted and α,α,α‐trisubstituted acyl chlorides give with N‐hydroxy‐2‐thiopyridone, the corresponding ester. The decomposition of this compound in tetrachlorotethane or in bromotrichloromethane as solvent and halogen atom source results in the formation of new very hindered secondary R1R2CHX (R1 = iPr or tBu; R2 = iPr or tBu; X = Cl or Br) and tertiary R1R2R3CX (R1 = R2 = R3 = iPr; R1= tBu, R2= iPr, R3= et or Me, X = Cl) alkylhalides.