Home About us Contact
|
Home About us Contact | ||
|
|
||
Diethyl
Terms modified by Diethyl Selected AbstractsThe Electrochemical Oxidation of N,N -Diethyl- p -Phenylenediamine in DMF and Analytical Applications.ELECTROANALYSIS, Issue 11 2003Part I: Mechanistic Study Abstract The electrochemical oxidation of N,N -diethyl- p -phenylenediamine in dimethylformamide has been studied at platinum and gold microdisk electrodes of various radii between 6.7 and 66,,m. The voltammetric responses revealed two electrochemically reversible waves the second of which becomes larger at higher concentrations and bigger electrode radii. The voltammetric signals have been modelled and the electrochemical oxidation reaction is not inconsistent with an ECrevECE reaction. Kinetic parameters are reported. [source] Reaction with N,N -Diethyl- p -phenylenediamine: A Procedure for the Sensitive Square-Wave Voltammetric Detection of ChlorineELECTROANALYSIS, Issue 8 2003Hugo Seymour Abstract The reaction of chlorine and N,N -diethyl- p -phenylenediamine has been studied as a means of generating an analytical voltammetric signal of much improved sensitivity and selectivity for the detection of the former than is possible via direct electrolysis. A reaction mechanism is suggested whereby the chlorine attacks the primary amine of DEPD to form the N -chlorinated product that shows a much enhanced signal under conditions of square-wave voltammetry than does chlorine itself. The analytical parameters were found to vary with concentration of DEPD and a linear range from 17 to 495,,M was achievable with a corresponding limit of detection of 6.8,,M [source] Synthesis and Structural Characterisation of Palladium and Group-12 Metal Complexes with a Hybrid Phosphanylphosphonate Ferrocene LigandEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 5 2006Abstract Diethyl [1,-(diphenylphosphanyl)ferrocenyl]phosphonate (1) was synthesised by stepwise metallation/functionalisation of 1,1,-dibromoferrocene and studied as a ligand for palladium(II) and group-12 metals. Treatment of [PdCl2(cod)] (cod = ,2:,2 -cycloocta-1,5-diene) with 1 in 1:1 or 1:2 molar ratios gave, respectively, the dinuclear, chloride-bridged complex [{Pd(,-Cl)Cl(1 -,P2)}2] (2) and the mononuclear complex trans -[PdCl2(1 -,P2)2] (3), where 1 coordinates exclusively through the phosphane function. The reactions between 1 and group-12 metal bromides MBr2 in a 1:1 molar ratio gave the adducts [MBr2(1)] [M = Zn (4), Cd (5), and Hg (6)], whose crystal structures change considerably with the metal ion. Thus, whereas 4 is a molecular complex with 1 coordinating as an O1,P2 -chelate, its cadmium(II) analogue is a polymer built up from symmetric {CdBr(,-Br)}2 units interconnected by pairs of O1,P2 -bridging phosphanylphosphonate ligands. Finally, the mercury(II) complex 6 is a halide-bridged dimer, [{Hg(,-Br)Br(1 -,P2)}2]. However, this compound is structurally fluxional in solution (NMR spectra) and, in the crystal, it attains a structure similar to 5 owing to weak interactions between mercury and phosphonate-O1 atoms from adjacent molecules. An isomer to 6, [{HgBr2(1 -,2O1,P2)}2] (7), was isolated from attempted alkylation of 6 and structurally characterised as a dimer, where ligands 1 bridge two {HgBr2} units. All compounds were studied by spectroscopic methods (IR, NMR, mass) and the solid-state structures of 1, 2·,H2O, 3·4,CHCl3, 4, 5, 6·5,C6H6, and 7 have been determined by single-crystal X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Syntheses, spectral property, and antimicrobial activities of 6-,-amino dibenzo [d,f][1,3,2]dioxaphosphepin 6-oxidesHETEROATOM CHEMISTRY, Issue 1 2007M. Kasthuraiah Diethyl ,-aminophosphonates (4) were prepared in excellent yield from three-component reaction of aldehydes (1), amines (2), and triethylphosphite (3) under solvent-free conditions in the presence of ceric ammonium nitrate (CAN) and were reacted with 2,2,-dihydroxybiphenyl (5) using p -toluene sulfonic acid monohydrate (PTSA) as a catalyst to obtain 6-,-aminodibenzo[d f][1,3,2]dioxaphosphepin 6-oxides (6) in good yield. It is a first report on the cyclizations of 4 with 5. An antimicrobial activity of numbers of 6 is evaluated. © 2007 Wiley Periodicals, Inc. Heteroatom Chem 18:2,8, 2007; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20244 [source] Stereoselective synthesis and biological activities of diethyl (E)-{[4-cyano-5-[[(disubstitutedamino)methylene]amino]-3-(methylthio)- 1H -pyrazol-1-yl]substituited phenylmethyl}phosphonatesJOURNAL OF HETEROCYCLIC CHEMISTRY, Issue 3 2009Lin-Xia Xiao Diethyl {[5-amino-4-cyano-3-(methylthio)-1H -pyrazol-1-yl]substitutedphenylmethyl}phosphonates 3 were efficiently synthesized via the condensation of [(1-hydrazino)substitutedphenylmethyl]phosphonates 1 with 2-[bis(methylthio)methylene]malononitrile 2. 3 reacted with triethyl orthoformate to afford diethyl (E)-{[4-cyano-5-[(ethoxymethylene)amino]-3-(methylthio)-1H -pyrazol-1-yl]substitutedphenylmethyl}phosphonates 4, which reacted with various secondary amines at room temperature to provide the target compounds 5 in good yields. Their structures were confirmed by ir, 1H and 31P NMR, mass spectroscopy, and elemental analyses. The results of preliminary bioassay indicated that compounds 5 possess potent herbicidal activity against the roots of dicotyledonous (oil rape) plants at the dosage of 100 mg/L, and compounds 5c and 5g exhibit 80.8% and 76.7% inhibitory activity against Colletotrichum gossypi at the concentration of 50 mg/L, respectively. Abstract end data: J. Heterocyclic Chem., 46, 555 (2009). [source] A bioassay for mosquito repellency against Aedes aegypti: method validation and bioactivities of DEET analoguesJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 1 2010Alexander Jahn Abstract Objectives Vector-borne diseases are still a major mortality factor in Africa and South-east Asia and effective mosquito repellents are therefore needed. An efficient and safe in-vitro assay system using artificial blood and skin substitute could facilitate the development of novel repellents, as most assays currently rely on human subjects or vertebrate whole blood. Moreover, examining the skin permeation profiles could provide safer mosquito repellents. The new assay system could serve as an initial system for testing new repellent candidates upon validation with DEET and its analogues. MethodsN,N -Diethyl- meta -toluamide (DEET) and five analogues were synthesised and used to validate a novel in-vitro bioassay using artificial blood and collagen membrane. Repellency against Aedes aegypti was correlated with lipophilicity and skin permeation. Key findings The new in-vitro assay showed good reproducibility (interday relative standard deviation <10% at high concentrations). Four of the five DEET analogues showed repellency similar or superior to that of DEET. Repellency correlated linearly with lipophilicity but stronger repellents tended to permeate skin better. Conclusions The new in-vitro assay using blood substitute and collagen membrane significantly simplifies screening of possible mosquito repellents. Lipophilicity as well as skin permeation profiles should be considered before testing of compounds that are candidates for mosquito repellents. [source] Advanced flame-retardant epoxy resins from phosphorus-containing diolJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 16 2005M. José Alcón Abstract Phosphorus-containing epoxy systems were prepared from isobutylbis(hydroxypropyl)phosphine oxide (IHPO) and diglycidyl ether of bisphenol A (DGEBA). Diethyl- N,N -bis(2-hydroxyethyl) aminomethyl phosphonate (Fyrol 6) could not be incorporated into the epoxy backbone by a reaction with either epichlorohydrin or DGEBA because intramolecular cyclization took place. The curing behavior of the IHPO,DGEBA prepolymer with two primary amines was studied, and materials with moderate glass-transition temperatures were obtained. V-0 materials were obtained when the resins were tested for ignition resistance with the UL-94 test. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3510,3515, 2005 [source] N,N -Diethyl- N,-[(E)-4-pyridylmethylene]benzene-1,4-diamine: a combined X-ray and density functional theory studyACTA CRYSTALLOGRAPHICA SECTION C, Issue 8 2009Rüdiger W. Seidel The crystal structure of the title compound, C16H19N3, comprises neutral molecules of a dipolar Schiff base chromophore. A density functional theory (DFT) optimized structure at the B3LYP/6-31G(d) level is compared with the molecular structure in the solid state. The compound crystallizes in the noncentrosymmetric space group Pna21 with a herring-bone packing motif and is therefore a potential candidate for nonlinear optical effects in the bulk. [source] (2S,3R,4S,5R)-Diethyl 2-(10,10-dimethyl-3,3-dioxo-3,6 -thia-4-azatricyclo[5.2.1.01,5]decan-4-ylcarbonyl)-5-phenylpyrrolidine-3,4-dicarboxylate: a novel isomorphous-by-addition compoundACTA CRYSTALLOGRAPHICA SECTION C, Issue 1 2009Graeme J. Gainsford The title compound, C27H36N2O7S, (I), is isomorphous by addition with the dimethyl ester analogue [Garner, Dogan, Youngs, Kennedy, Protasiewicz & Zaniewski (2001). Tetrahedron, 57, 71,85], (II), by replacing two methyl ester H atoms with two methyl groups. With the exception of the conformation of one of the ester groups, the molecules are almost superimposable. Likewise, apart from a slightly larger c axis in (I), few differences in the cell packing of (I) and (II) are found, with both dominated by the same C,H...O hydrogen bonds. Full synthetic and spectroscopic details of (I) are given. The molecular synthesis is important as an example of chiral auxiliary-assisted 1,3-dipolar cycloaddition of an azomethine ylid. [source] N1,N1 -Diethyl- N2 -(2,3,4,6-tetra- O -acetyl-,- d -glucopyranosyl)acetamidineACTA CRYSTALLOGRAPHICA SECTION C, Issue 11 2001María Jesús Diánez The solid-state conformation of the title compound, C20H32N2O9, has been determined at 150,K. The pyranose ring has a distorted chair conformation. Among the possible conformations of the C,N glycosidic bond, that of the E rotamer is observed and a short intramolecular Cmethyl,O contact may partly stabilize this conformation. Crystal cohesion is stabilized by an extensive network of weak C,H,O hydrogen bonds and close contacts. [source] ChemInform Abstract: Condensation of Diethyl 2,4,6-Trioxoheptanedioate with 2-(Aryliminomethyl)phenols.CHEMINFORM, Issue 4 20093-b]pyridines., A New Synthesis of Chromeno[ Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source] Synthesis of Substituted Pyrrolo[3,2-f]quinolines (IV) from 5-Aminoindoles (I) and Diethyl Oxaloacetate.CHEMINFORM, Issue 45 2007S. A. Yamashkin Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Direct One-Step Synthesis of Azaheterocyclic Phosphonates from Diethyl ,-Chloro-1-alkynylphosphonates and Hydrazines.CHEMINFORM, Issue 33 2007Abdullatif Azab Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Synthesis of Indenes via Palladium-Catalyzed Carboannulation of Diethyl 2-(2-(1-Alkynyl)phenyl)malonate and Organic HalidesCHEMINFORM, Issue 36 2006Li-Na Guo Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract, please click on HTML or PDF. [source] Two New Irreversible Inhibitors of Dihydrodipicolinate Synthase: Diethyl (E,E)-4-Oxo-2,5-heptadienedioate and Diethyl (E)-4-Oxo-2-heptenedioate.CHEMINFORM, Issue 25 2005Jennifer J. Turner Abstract For Abstract see ChemInform Abstract in Full Text. [source] A Concise Synthesis of Diethyl 1-(tert-Butoxycarbonylamino)-1-alkenylphosphonates.CHEMINFORM, Issue 14 2005Katarzyna Blazewska Abstract For Abstract see ChemInform Abstract in Full Text. [source] Vicinal Dianions of Diethyl ,-Aroylsuccinates: Preparation of Functionalized-2,3-dihydrofurans and -furans, and Diaxial 2,4-Diaryl-3,7-dioxabicyclo[3.3.0]octanes.CHEMINFORM, Issue 4 2004Manat Pohmakotr Abstract For Abstract see ChemInform Abstract in Full Text. [source] Synthesis of rhombohedral strontium carbonate aggregates at the water/hexamethylene interface with cetyltrimethylammonium bromideCRYSTAL RESEARCH AND TECHNOLOGY, Issue 8 2008Long Chen Abstract Unusual rhombohedral strontium carbonate (SrCO3) aggregates have been synthesized in situ from strontium nitrate by the slow release of carbon dioxide by alkaline hydrolysis of diethyl carbonate at the water/hexamethylene interface in the presence of cetyltrimethylammonium bromide (CTAB). Transmission electron microscopy, Fourier transform infrared spectroscopy and X-ray powder diffractometry were used to characterize the products. The results indicate that rhombohedral SrCO3 aggregates are obtained with weaker crystallinity and sizes of several micrometers. The possible formation mechanism of the SrCO3 aggregates at the interface is discussed, which can be interpreted by particle-aggregation based non-classical crystallization laws. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The Electrochemical Oxidation of N,N -Diethyl- p -Phenylenediamine in DMF and Analytical Applications.ELECTROANALYSIS, Issue 11 2003Part I: Mechanistic Study Abstract The electrochemical oxidation of N,N -diethyl- p -phenylenediamine in dimethylformamide has been studied at platinum and gold microdisk electrodes of various radii between 6.7 and 66,,m. The voltammetric responses revealed two electrochemically reversible waves the second of which becomes larger at higher concentrations and bigger electrode radii. The voltammetric signals have been modelled and the electrochemical oxidation reaction is not inconsistent with an ECrevECE reaction. Kinetic parameters are reported. [source] Reaction with N,N -Diethyl- p -phenylenediamine: A Procedure for the Sensitive Square-Wave Voltammetric Detection of ChlorineELECTROANALYSIS, Issue 8 2003Hugo Seymour Abstract The reaction of chlorine and N,N -diethyl- p -phenylenediamine has been studied as a means of generating an analytical voltammetric signal of much improved sensitivity and selectivity for the detection of the former than is possible via direct electrolysis. A reaction mechanism is suggested whereby the chlorine attacks the primary amine of DEPD to form the N -chlorinated product that shows a much enhanced signal under conditions of square-wave voltammetry than does chlorine itself. The analytical parameters were found to vary with concentration of DEPD and a linear range from 17 to 495,,M was achievable with a corresponding limit of detection of 6.8,,M [source] Chlorpyrifos-induced DNA damage in rat liver and brainENVIRONMENTAL AND MOLECULAR MUTAGENESIS, Issue 6 2008Anugya Mehta Abstract Chlorpyrifos (O,O'-diethyl- O -3,5,6-trichloro-2-pyridyl phosphorothionate, CPF) is a broad spectrum organophosphate pesticide used to control a variety of pests. The present study was undertaken to test the in vivo genotoxic potential of CPF in rats, using the single cell gel electrophoresis (or comet) assay. The rats were administered 50 mg and 100 mg CPF/kg body weight daily for 1, 2, and 3 days as well as 1.12 mg and 2.24 mg CPF/kg body weight for 90 days. The level of DNA damage was estimated by scoring 100 cells per animal, dividing into five types: types 0, I, II, III, and IV. The results clearly indicate that exposure to CPF, acutely or chronically, caused a dose-dependent increase in DNA damage in the liver and brain of rats. From the present study, it can be concluded that CPF exhibits genotoxic potential in vivo. Environ. Mol. Mutagen., 2008. © 2008 Wiley-Liss, Inc. [source] Structural Characterization of N -Methylpyridoxine (MePN; PN = Vitamin B6) and Its Diorganotin Complexes [SnR2(MePN-H)]I (R = Me, Et, Bu and Ph)EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 15 2003José S. Casas Abstract For comparison with the corresponding pyridoxine complexes we have prepared dimethyl-, diethyl-, dibutyl- and diphenyltin(IV) complexes of N -methylpyridoxine (MePN). The compounds [SnMe2(MePN,H)]I (1), [SnEt2(MePN,H)]I (2), [SnBu2(MePN,H)]I (3) and [SnPh2(MePN,H)]I·H2O (4) were isolated and characterized by IR, Raman, Mössbauer, 1H, 13C and 119Sn NMR spectroscopy, and by EI and FAB mass spectrometry. The crystal structures of [HMePN]I and of compounds 1, 2·2H2O and 3 were determined by X-ray diffractometry. Their lattices contain dimeric [SnR2(MePN,H)]22+ units (R = Me, Et, Bu) in which two bridging-chelating methylpyridoxinato anions link pentacoordinate Sn atoms with coordination polyhedra closer to square pyramids than to trigonal bipyramids. NMR results show that the dimeric cations persist in (CD3)2SO. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Suppressing the Anionic Fries Rearrangement of Aryl Dialkylcarbamates; the Isolation of a Crystalline ortho -Deprotonated CarbamateEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 4 2008Felipe García Abstract In the presence of organolithium bases phenyl dialkylcarbamates have previously been shown to undergo facile rearrangement to yield the corresponding salicylamides. However, heterometallic lithium diethyl(2,2,6,6-tetramethylpiperidido)zincate achieves the clean directed ortho -metallation (DoM) of phenyl dialkylcarbamates, with [C6H4{OC(O)NMe2}{Zn(-TMP)Et}Li]2 having been structurally characterized. DFT studies point to a stepwise deprotonative mechanism in which the zincate reagent exhibits kinetic amido basicity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008) [source] A Radical Version of the Bromo- and the Iodocyclization of Bis(homoallylic) Alcohols , The Synthesis of Halogenated Tetrahydrofurans by Stereoselective Alkoxyl Radical Ring ClosuresEUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 20 2003Jens Hartung Abstract A new synthesis of bromo- and iodomethyl-substituted tetrahydrofurans has been devised. The sequence starts with the conversion of aryl-functionalized bis(homoallylic) alcohols 1 into N -alkenoxythiazole-2(3H)-thiones 6 or pyridine-2(1H)-thiones 7. When photolyzed in the presence of appropriate trapping reagents, thiones 6 and 7 efficiently liberated substituted 4-penten-1-oxyl radicals 2, which underwent synthetically useful 5- exo -trig cyclizations. Cyclized radicals 3 were trapped with BrCCl3 or an adequate iodine atom donor (either n -C4F9I or diethyl 2-iodo-2-methyl malonate) to provide halocyclization products 4 or 5. This strategy has been applied for the synthesis of 3-, 4-, or 5-phenyl-substituted 2-(1-bromo-1-methylethyl)tetrahydrofurans 4a,c (75,90%, 36,96% de), which were not attainable as major products from polar, for example NBS-mediated, bromocyclizations. Aryl-substituted 2-iodomethyl tetrahydrofurans 5 (46,80%) were prepared in a similar way starting from N -alkenoxypyridine-2(1H)-thiones 7 and a suitable iodine atom donor. Diastereomerically pure iodides cis - 5 and trans - 5 served as starting materials for a stereochemical analysis of disubstituted tetrahydrofurans by NMR spectroscopy and X-ray diffraction analysis. The results of this investigation clarified that all new alkoxyl radical cyclizations followed in terms of regio- and diastereoselectivity the general guidelines which had been established for this type of ring-closure reaction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source] Acylation of lysophosphatidylcholine plays a key role in the response of monocytes to lipopolysaccharideFEBS JOURNAL, Issue 13 2003Bernhard Schmid Mononuclear phagocytes play a pivotal role in the progression of septic shock by producing tumor necrosis factor-, (TNF-,) and other inflammatory mediators in response to lipopolysaccharide (LPS) from Gram-negative bacteria. Our previous studies have shown monocyte and macrophage activation correlate with changes in membrane phospholipid composition, mediated by acyltransferases. Interferon-, (IFN-,), which activates and primes these cells for enhanced inflammatory responses to LPS, was found to selectively activate lysophosphatidylcholine acyltransferase (LPCAT) (P < 0.05) but not lysophosphatidic acid acyltransferase (LPAAT) activity. When used to prime the human monocytic cell line MonoMac 6, the production of TNF-, and interleukin-6 (IL-6) was approximately five times greater in cells primed with IFN-, than unprimed cells. Two LPCAT inhibitors SK&F 98625 (diethyl 7-(3,4,5-triphenyl-2-oxo2,3-dihydro-imidazole-1-yl)heptane phosphonate) and YM 50201 (3-hydroxyethyl 5,3,-thiophenyl pyridine) strongly inhibited (up to 90%) TNF-, and IL-6 production in response to LPS in both unprimed MonoMac-6 cells and in cells primed with IFN-,. In similar experiments, these inhibitors also substantially decreased the response of both primed and unprimed peripheral blood mononuclear cells to LPS. Sequence-based amplification methods showed that SK&F 98625 inhibited TNF-, production by decreasing TNF-, mRNA levels in MonoMac-6 cells. Taken together, the data from these studies suggest that LPCAT is a key enzyme in both the pathways of activation (priming) and the inflammatory response to LPS in monocytes. [source] Complexes of diethyl-2-amino-2-oxoethylphosphonate with lanthanide nitratesHETEROATOM CHEMISTRY, Issue 2 2003Jordanka Petrova Lanthanide complexes LnL2(NO3)33a,f are obtained where Ln is La, Ce, Sm, Eu, Er, and Yb and L is the diethyl 2-amino-2-oxoethylphosphonate. They were characterized by elemental analysis, IR, and NMR spectroscopy. Monodentate coordination by the phosphoryl group is suggested for the ligand on the basis of the spectral data. The stabilization is achieved by including a molecule of the solvent in the complexes 3a,d. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:128,131, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10112 [source] Preparation, structure, and optical properties of chiral sulfoxides and disulfoxide with a trithiole ringHETEROATOM CHEMISTRY, Issue 1 2003Takeshi Kimura Optically active 4,9-diethyl[1,4]-dithiino[5,6- f]benzo[1,2,3]trithiole 5-oxide (3) and 4,9-diethyl[1,4]dithiino[5,6- f]benzo[1,2,3]trithiole 5,8-dioxide (4) were obtained by the asymmetric oxidation of 6,11-diethyl[1,4]dithiino[5,6- h]benzo[1,2,3,4,5]pentathiepin (1). The reaction was accompanied by desulfurization and ring-contraction reactions of the pentathiepin ring. Similarly, optically active 4,8-diethyl[1,3]dithiolo[4,5- f]benzo[1,2,3]trithiole 5-oxide (7) was produced by the analogous asymmetric oxidation of 6,10-diethyl[1,3]dithiolo[4,5- h]benzo[1,2,3,4,5]pentathiepin (2). The specific rotations of 3, 4, and 7 were measured in chloroform, and their optical purity was verified by 1H NMR with a shift reagent [Eu(hfc)3]. The structures of 4 and 7 were determined by X-ray crystallography using Cu K, radiation, and the absolute configuration of the sulfinyl group was examined based on the Flack parameter, which revealed that 4 has an RR configuration, while 7 has an S configuration. The circular dichroism spectra of 3, 4, and 7 were measured in chloroform. © 2003 Wiley Periodicals, Inc. Heteroatom Chem 14:88,94, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.10104 [source] Mixed Isobutylphobane/N-Heterocyclic Carbene Ruthenium- Indenylidene Complexes: Synthesis and Catalytic Evaluation in Olefin Metathesis ReactionsADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 11-12 2010Xavier Sauvage Abstract Two new second generation ruthenium(II) dichloride-indenylidene complexes [RuCl2(9-isobutylphosphabicyclo[3.3.1]nonane)(NHC)(3-phenyl-1-indenylidene)], where NHC=1,3-bis(2,4,6-trimethylphenyl)imidazolin-2-ylidene (SIMes) or its unsaturated imidazol-2-ylidene analogue (IMes), were isolated in high yields upon heating a tetrahydrofuran (THF) solution of the diphosphane complex [RuCl2(isobutylphobane)2(3-phenyl-1-indenylidene)] with a two-fold excess of the corresponding imidazol(in)ium-2-carboxylate zwitterions. Both products were characterized by 1H, 13C, and 31P,NMR spectroscopy, and the molecular structure of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was determined by X-ray diffraction analysis. A close inspection of the packing structure revealed the presence of different types of intra- and intermolecular interactions that enhanced the global stability of the crystals, while low temperature NMR experiments showed the existence of two distinct rotational isomers due to the unsymmetrical nature of the phobane ligand. The catalytic activity of both compounds was assessed in olefin metathesis using benchmark ring-opening metathesis polymerization, ring-closing metathesis (RCM), and cross-metathesis reactions, and compared with those of related first and second generation ruthenium-benzylidene and indenylidene catalyst precursors. Kinetic studies confirmed the high thermal stability of the mixed isobutylphobane/N-heterocyclic carbene complexes, which suffered from a slow initiation efficiency compared to other catalytic systems based on the tricyclohexylphosphane ligand. However, the remarkable robustness of [RuCl2(isobutylphobane)(SIMes)(3-phenyl-1-indenylidene)] was beneficial for performing the RCM of diethyl 2,2-bis(2-methylallyl)malonate. Monitoring the formation of the ruthenium-methylidene active species [RuCl2(isobutylphobane)(SIMes)(CH2)] derived from this precursor further demonstrated its ability to sustain long reaction times and high temperatures required to carry out the RCM of tetrasubstituted olefins. [source] Stereoselective Synthesis of Metalated Cyclobutyl DerivativesADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 7-8 2009Einav Tsoglin Abstract Treatment of Z -vinyl carbamates with dicyclopentadienyl(diethyl)zirconium [Et2ZrCp2] leads to cyclobutyl-zirconocene derivatives in good yields and as a unique diastereoisomer. The reaction proceeds through a carbometalative ring-expansion followed by an intramolecular migratory insertion. [source] Novel amphiphilic polymer gel electrolytes based on (PEG- b -GMA)- co -MMAJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2010Dan Luo Abstract Amphiphilic conetwork,structured copolymers containing different lengths of ethylene oxide (EO) chains as ionophilic units and methyl methacrylate (MMA) chains as ionophobic units were prepared by free radical copolymerization and characterized by FTIR and thermal analysis. Polymer gel electrolytes based on the copolymers complexed with liquid lithium electrolytes (dimethyl carbonate (DMC) : diethyl carbonate (DEC) : ethylene carbonate (EC) = 1 : 1 : 1 (W/W/W), LiPF6 1.0M) were characterized by differential scanning calorimetry and impedance spectroscopy. A maximum ion conductivity of 4.27 × 10,4 S/cm at 25oC was found for the polymer electrolyte based on (PEG2000- b -GMA)- co -MMA with long EO groups. Moreover, the effect of temperature on conductivity of the amphiphilic polymer electrolytes obeys the Arrhenius equation. The good room temperature conductivity of the polymer electrolytes is proposed to relate to the enhancement in the amorphous domain of the copolymers due to their amphiphilic conetwork structure. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] | ||||||||||||||||||||||||||||||||||||||||