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Direct Reaction (direct + reaction)
Selected AbstractsChemInform Abstract: A Simple One-Pot Synthesis of New Imidazol-2-yl-1H-quinolin-2-ones from the Direct Reaction of 2-Chloroquinolin-3-carbaldehyde with Aromatic o-Diamines.CHEMINFORM, Issue 20 2010Rodrigo Abonia Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 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] Aromatic Hydrocarbon-Catalyzed Direct Reaction of Sulfur and Sodium in a Heterogeneous System: Selective and Facile Synthesis of Sodium Monosulfide and Disulfide.CHEMINFORM, Issue 37 2003Toshikazu Takata Abstract For Abstract see ChemInform Abstract in Full Text. [source] The role of cysteine and cysteine,S conjugates as odour precursors in the flavour and fragrance industry ,FLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2008Christian Starkenmann Abstract Volatile sulphur compounds are important odorants in the flavour and fragrance industries. Recent developments in the field have reinvigorated sulphur compound research, particularly with regard to the precursor compounds of volatile thiols. The present review concentrates on the role of cysteine and cysteine,S conjugates as precursor compounds for a variety of aromas and examines the chemical and enzymatic pathways of degradation and biotransformation. Cysteine is an important source of sulphur in flavour chemistry and may be degraded into hydrogen sulphide, which can further participate in other reactions. Direct reactions of cysteine and the pathways particular to various flavours and fragrances are discussed, with an emphasis on the precursor compounds cysteine,S conjugates. The importance of cysteine precursors in plants, including onion, wine, passion fruit, bitter orange, asparagus and bell pepper and the formation of natural scents in cats and humans are discussed. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis of Ternary Titanium Aluminum Carbides Using Self-Propagating High-Temperature Synthesis TechniqueJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 12 2001Micha, opaci Different ternary carbide phases, namely Ti3AlC2, Ti3AlC, and Ti2AlC, were successfully synthesized in a self-sustaining regime. Direct reactions among elemental powders of titanium, aluminum, and carbon are strongly exothermic, and the resulting reaction products consist of binary carbides and they are partially molten. The use of TiAl, instead of elemental titanium and aluminum, significantly reduces the combustion temperature. As a result, ternary titanium aluminum carbide phases are formed. In addition, the combustion-synthesized products are not sintered and easy to deagglomerate. Reaction conditions and X-ray diffraction patterns of different ternary phases formed in a self-sustaining regime are presented. [source] Does morphological variation between young-of-the-year perch from two Swedish lakes depend on genetic differences?ECOLOGY OF FRESHWATER FISH, Issue 2 2010M. Heynen Heynen M, Hellström G, Magnhagen C, Borcherding J. Does morphological variation between young-of-the-year perch from two Swedish lakes depend on genetic differences? Ecology of Freshwater Fish 2010: 19: 163,169. © 2009 John Wiley & Sons A/S Abstract,,, Different local environmental conditions have often been found to generate phenotypic diversity. In the present study we examined morphological differences between young-of-the-year perch from two lake populations with differences in size-specific predation risk. A common garden setup was used to examine the genetic and environmental components of the morphological variation. We found differences in head and jaw length and slight differences in body depth between the wild young-of-the-year perch from Lake Ängersjön and Lake Fisksjön. The differences found between the wild fish from the two lakes were not maintained under common garden rearing. The observed morphological divergence between the wild young-of-the-year perch from Lake Ängersjön and Lake Fisksjön seems to stem mainly from a plastic response to different environmental conditions in the two lakes. It is clear that the morphological traits are not influenced by direct reaction to the size-specific risk of cannibalism, but probably stem from a combination of different environment characteristics, including resource and habitat use, and the density of other piscivores, such as pike. [source] Nickel Complexes of N/O -Functionalized N-Heterocyclic Carbenes as Precatalysts for Michael Reactions in Air at Room Temperature Under the Much Preferred Base-Free ConditionsEUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 13 2009Sriparna Ray Abstract A series of several new nickel precatalysts supported overN/O -functionalized N-heterocyclic carbenes (NHC) for the Michael reactions of ,-dicarbonyl, ,-keto ester, ,-diester, and ,-cyano ester compounds with ,,,-unsaturated carbonyl compounds in air at ambient temperature under the much preferred base-free conditions are reported. Specifically, the nickel complexes, [1-(R1 -aminocarbonylmethyl)-3-R2 -imidazol-2-ylidene]2Ni [R1 = 2-C6H4(OMe); R2 = Me (1b), iPr (2b), CH2Ph (3b) and R1 = 2-CH2C4H3O; R2 = Me (4b), CH2Ph (5b)] carried out the highly convenient base-free Michael addition of the activated C,H compounds across ,,,-unsaturated carbonyl compounds in air at room temperature. The complexes 1b,5b were synthesized by the direct reaction of the respective imidazolium chloride salt with NiCl2·6H2O in CH3CN in the presence of K2CO3 as a base. The exceptional stability of 1b,5b has been attributed to the deeply buried nickel,NHC ,-bonding molecular orbitals as evidenced from the density functional theory (DFT) studies. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Fluoride-Free Hiyama and Copper- and Amine-Free Sonogashira Coupling in Air in a Mixed Aqueous Medium by a Series of PEPPSI-Themed Precatalysts,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 12 2009Chandrakanta Dash Abstract A new series of robust, user-friendly, and highly active PEPPSI-themed (pyridine-enhanced precatalyst preparation, stabilization and initiation) (NHC)PdX2(pyridine)-type (X = Cl, Br) precatalysts of C4,C5 saturated imidazole- (1,4) and triazole-based (5 and 6) N-heterocyclic carbenes for the Hiyama and Sonogashira couplings under amenable conditions are reported. Specifically 1,6 efficiently catalyze the fluoride-free Hiyama coupling of aryl halides with PhSi(OMe)3 and CH2=CHSi(OMe)3 in air in the presence of NaOH as a base in a mixed aqueous medium (dioxane/H2O, 2:1 v/v). Along the same lines, these 1,6 precatalysts also promote the Cu-free and amine-free Sonogashira coupling of aryl bromides and iodides with phenylacetylene in air and in a mixed aqueous medium (DMF/H2O, 3/1 v/v). The complexes 1,6 were synthesized by the direct reaction of the respective imidazolinium and triazolium halide salts with PdCl2 in pyridine in the presence of K2CO3 as a base. DFT studies on the catalytically relevant palladium(0) (NHC)Pd(pyridine) precursors 1a,6a reveal significant donation from the N-heterocyclic carbene lone pair onto the unfilled ,* orbital of the trans Pd,pyridine bond. This weakens the Pd-bound "throwaway" pyridine ligand, and its dissociation marks the initiation of the catalytic cycle.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source] Hydrothermal Synthesis of Structure- and Shape-Controlled Manganese Oxide Octahedral Molecular Sieve NanomaterialsADVANCED FUNCTIONAL MATERIALS, Issue 9 2006W.-N. Li Abstract Highly uniform single-crystal Na-OMS-2 (OMS: octahedral molecular sieve), pyrolusite, and ,-MnO2 nanostructures with an interesting 3D urchinlike morphology have been successfully prepared using a hydrothermal method based on a mild and direct reaction between sodium dichromate and manganese sulfate. The crystal phases, shapes, and tunnel sizes of the manganese dioxide nanostructures can be tailored. Reaction temperature, concentrations of the reactants, and acidity of the solution play important roles in controlling the synthesis of these manganese dioxides. Field-emission scanning electron microscopy and transmission electron microscopy (TEM) studies show that the nanomaterials obtained are constructed of self-assembled nanorods. X-ray diffraction and TEM results indicate that the constituent manganese dioxide particles are single-crystalline materials. Energy dispersive X-ray analysis and magnetic studies imply that chromium cations may be incorporated into the framework and/or tunnels of the manganese dioxides. A mechanism for the growth of manganese dioxides with urchinlike architectures is proposed. [source] Mechanochemical Synthesis of Blue Luminescent Alkyl/Alkenyl-Passivated Silicon NanoparticlesADVANCED MATERIALS, Issue 22 2007S. Heintz A mechanochemical method for the simultaneous one-step production and functionalization of silicon nanoparticles is presented. Fresh surface created through mechanical attrition of the silicon during high energy ball milling (HEBM) allows for direct reaction between the silicon and the reactive alkene or alkyne media, resulting in a covalent linkage. The resulting nanoparticles exhibit strong blue luminescence, indicative of small nanoparticle sizes and a functionalized surface. [source] The primary kinetic hydrogen isotope effect in the deprotonation of a nitroalkane by an intramolecular carboxylate groupJOURNAL OF PHYSICAL ORGANIC CHEMISTRY, Issue 7-8 2008Nicholas Backstrom Abstract The rates of racemization of optically active nitropentanoic acid, and 4-deuteronitropentanoic have been compared. The rate ratio (kie) is kH/kD,=,5.68(±0.17) at 31°C, in good agreement with that determined by Lewis et al. for base-catalysed deprotonations using iodine-trapping methods. In a more detailed study, optically active 4-nitro-4-phenylbutanoic acid (NPBA) has also been prepared and rates of racemization measured in dimethoxyethane:water. With less than a full equivalent of triethylamine, rates are proportional to [Et3N:]/[NPBA]. For 1,<,[Et3N:]/[NPBA],<,2, rates are independent of the ratio, consistent with racemization being dominated by deprotonation of the nitroalkane by the intramolecular carboxylate group. The solvent isotope effect is ,=,0.73(±0.04) and rates of exchange with D2O are equal to rates of racemization. Comparison with rates of racemization by acetate of the methyl ester yielded an effective molarity (EM,=,13.7) for the intramolecular carboxylate. The kie for racemizations of NPBA and 4-deutero-NPBA is kH/kD,=,5.78 at 25°C, and for 20,<,T,<,50°C, E,,,E,=,5.5(±0.1) and AH/AD,=,0.63(±1.03). For the acetate catalysed racemizations of the methyl ester, 25°C, kH/kD,=,7.43 with E,,,E,=,5.2,kJ,mol,1 and AH/AD,=,1.08. In neither case is there any indication of a major tunnelling contribution on the isotopic rate ratio. A hitherto unrecognised mode of decomposition of nitronic acids, involving direct reaction with dissolved oxygen, has been identified. Copyright © 2008 John Wiley & Sons, Ltd. [source] Synthesis of a [60] fullerene,Functionalized isotactic polypropylene derivativeJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 20 2008Gerardo Martínez Abstract The covalent attachment of [60] fullerene (C60) to isotactic polypropylene (i-PP) is achieved by direct reaction in 1,2,4-trichlorobenzene (TCB) solution in the presence of dicumyl peroxide (DCP). The chemically modified pendant C60/i-PP polymers are soluble in chlorinated solvents and have been characterized by ultraviolet,visible and fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, cyclic voltametry, and thermogravimetric analysis. From the results it can be concluded that the modification of i-PP by grafting via a free-radical reaction competes with the possibility of chain scission of i-PP due to the presence of DCP. The functionalized polymers crystallize in the monoclinic crystal modification, and have high crystallinity. The incorporation of C60 significantly enhances the thermal stability of the i-PP. Electrochemical measurements demonstrate good electron acceptor properties of the fullerenated i-PP samples. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 6722,6733, 2008 [source] Synthesis of a [60]fullerene-functionalized poly(vinyl chloride) derivative by stereospecific chemical modification of PVCJOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 23 2007Gerardo Martínez Abstract The covalent attachment of [60]fullerene (C60) to two poly(vinyl chloride) (PVC) samples with different isotactic content is achieved by direct reaction in o -dichlorobenzene (o -DCB) solution in the presence of AIBN. The extent of fullerenation is controlled by varying the C60 feed ratio. The pendant C60 -chemically modified PVC polymers are soluble in tetrahydrofuran (THF) and have been characterized by UV,vis, NMR, FTIR, DSC, TGA, cyclic voltammetry, and SEM. The quantitative microstructural analysis after covalent attachment of the bulky C60 moiety to the PVC has been followed by 13C NMR spectroscopy. From the results it can be concluded that the modification of PVC by graft reaction through free radical reaction proceeds by a stereoselective mechanism. This conclusion has been confirmed on the basis of the increase of the glass-transition temperature (Tg) and the thermal stability of the C60 -chemical modified PVC samples. The fullerenated PVCs obtained show good electron acceptor properties, as evidenced by electrochemical investigations. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 5408,5419, 2007 [source] Direct Synthesis of PVA- g -PDMS in MicrosuspensionMACROMOLECULAR RAPID COMMUNICATIONS, Issue 5 2008Emmanuel Pouget Abstract The synthesis of P(VA- co -VAc)- graft -PDMS copolymers has been achieved in microsuspension by direct reaction between an epoxy-terminated PDMS and some pendant alcohol groups in P(VA- co -VAc). In this synthesis, the copolymer is used both as dispersant and reactant. The hydrophilic/hydrophobic character of the final material can be varied at will by incorporating various contents of epoxy-functionalized PDMS through optimized reaction conditions. The final composition was determined by TGA and 1H NMR. Products prepared from monofunctional PDMS were easily redispersed in water whereas a film of crosslinked materials, arising from difunctional PDMS, showed the best waterproofing as shown by contact angle analysis. [source] Fullerene-functionalized polycarbonate: Synthesis under microwave irradiation and nonlinear optical propertyPOLYMER ENGINEERING & SCIENCE, Issue 4 2006Huixia Wu Fullerenation of polycarbonate (PC), a commercially important optical polymer, was achieved by direct reaction of C60 and PC in the presence of azo-bis-isobutyronitrile (AIBN), using 1,1,2,2-tetrachloroethane as the solvent under microwave irradiation (MI). Compared with conventional heating process, MI could significantly enhance the rate of the fullerenation under identical reaction conditions. The C60 content of the fullerene-functionalized polycarbonate (C60 -PC) could be controlled via varying the C60/PC feed ratio and the reaction time. The C60 -PCs are soluble in common organic solvents such as THF and chloroform. The products were characterized by gel permeation chromatography, UV,vis, FTIR, TGA, DSC, 1H NMR, and 13C NMR. The reaction of C60 with PC under MI was monitored by electron spin resonance spectra, the fullerene radicals were detected in reaction solutions and also in the solid product polymers, indicating the radical mechanism of the reaction. The nonlinear optical property of C60 -PCs in THF was investigated by the open-aperture z -scan technique at 527 nm, and its nonlinear absorption coefficient was found to be in the same order as that of C60. POLYM. ENG. SCI., 46:399,405, 2006. © 2006 Society of Plastics Engineers [source] Grafting of functionalized silica particles with poly(acrylic acid)POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 6 2006Jarkko J. Heikkinen Abstract Two different methods to graft silica particles with poly(acrylic acid) (PAA) were studied. In the first method PAA was reacted with 1,1,-carbonyldiimidazole to give functionalized PAA. The resulting activated carbonyl group reacted easily with 3-aminopropyl-functionalized silica at low temperatures. In the second method 3-glycidoxypropyl-functionalized silica particles were reacted directly with PAA by using magnesium chloride as a catalyst. Different molecular weights of PAAs were used in order to investigate the effect of molecular weight on grafting yields in both methods. The grafting yields were determined with thermogravimetric analysis (TGA). All products were also investigated with IR. The results showed that the yields of reactions performed at ambient temperature by using 1,1,-carbonyldiimidazole-functionalized PAA were the same as with a direct reaction of unfunctionalized PAA and 3-aminopropyl-functionalized silica performed at 153°C. Also in reactions between 3-glycidoxypropyl-functionalized silica and PAA the yields were satisfactory. Copyright © 2006 John Wiley & Sons, Ltd. [source] Efficient and convenient preparation of water-soluble fullerenol,CHINESE JOURNAL OF CHEMISTRY, Issue 9 2004Jian-Min Zhang Abstract An efficient and convenient preparation of fullerenols was described. With polyethylene glycol (PEG) 400 as catalyst, fullerenols were conveniently synthesized via the direct reaction of fullerene with aqueous NaOH. By control of reaction conditions, either water-soluble C, fullerenol or water-insoluble C60 fullerenol could be obtained selectively. [source] Synthesis and Characterization of Two Novel, Mono-Lacunary Dawson Polyoxometalate-Based, Water-Soluble Organometallic Ruthenium(II) Complexes: Molecular Structure of [{(C6H6)Ru(H2O)}(,2 -P2W17O61)]8,EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 1 2006Yoshitaka Sakai Abstract The synthesis and structural characterization of a novel class of mono-lacunary Dawson polyoxometalate-(POM-)based, water-soluble organometallic complexes, which are expected to be effective homogeneous oxidation catalyst precursors in water, is described. The organometallic complexes K8[{(C6H6)Ru(H2O)}(,2 -P2W17O61)]·12H2O (1) and K8[{(p -cymene)Ru(H2O)}(,2 -P2W17O61)]·16H2O (2) were successfully prepared by direct reactions of the mono-lacunary Dawson POM K10[,2 -P2W17O61]·19H2O with the organometallic precursors [(C6H6)RuCl2]2 and [(p -cymene)RuCl2]2, respectively, in aqueous media and characterized by complete elemental analysis, thermogravimetric and differential thermal analyses (TG/DTA), and FT-IR and solution (1H, 13C, 31P, and 183W) NMR spectroscopy. The molecular structure of [{(C6H6)Ru(H2O)}(,2 -P2W17O61)]8, (1a), in which the binding of the cationic organometallic group {(C6H6)Ru(H2O)}2+ occurs through two oxygen atoms of the four available oxygen atoms in the mono-lacunary site of the POM, resulting in overall C1 symmetry, was successfully determined by single-crystal X-ray analysis. Interestingly, the hydrophilicity of the organometallic precursors is greatly enhanced by binding to a mono-lacunary Dawson POM with higher hydrophilicity. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source] Two 18, TiIV,5 -Cp-tris(sec -amido)-type complexes derived from 1H -imidazol-2-yl side-chain functionalized cyclopentadienesACTA CRYSTALLOGRAPHICA SECTION C, Issue 7 2009Xiaowu Wang Achiral {2-[2-(,5 -cyclopentadienyl)-2-methylpropyl]-1H -imidazolyl-,N1}bis(N,N -diethylamido-,N)titanium(IV), [Ti(C4H10N)2(C12H14N2)], (I), and closely related racemic (SR)-{2-[(,5 -cyclopentadienyl)(phenyl)methyl]-1H -imidazolyl-,N1}bis(N,N -diethylamido-,N)titanium(IV), [Ti(C4H10N)2(C15H12N2)], (II), have been prepared by direct reactions of Ti(NEt2)4 and the corresponding 1H -imidazol-2-yl side-chain functionalized cyclopentadienes. In compound (II), there are two crystallographically independent molecules of very similar geometries connected by a noncrystallographic pseudosymmetry operation akin to a 21 screw axis. All Ti-ligating N atoms in both (I) and (II) are in planar environments, which is indicative of an additional N,Ti p,,d, donation. This fact and the 18, nature of both (I) and (II) are additionally supported by quantum chemical single-point density functional theory (DFT) computations. [source] | |||||||||||||